2018
Papa, J. C.; Howard, J. M.; Rolland, J. P.
Three-mirror freeform imagers Proceeding
SPIE Optical Systems Design VII, vol. 10690, 2018.
Abstract | Links | BibTeX | Tags: CeFO related
@proceedings{Papa_spie2018,
title = {Three-mirror freeform imagers},
author = {J. C. Papa and J. M. Howard and J. P. Rolland},
doi = {10.1117/12.2314403},
year = {2018},
date = {2018-06-21},
urldate = {2018-06-21},
volume = {10690},
publisher = {SPIE Optical Systems Design VII},
abstract = {Driven by the development of freeform imaging systems, we have combined several concepts and techniques from the literature to analytically generate unobscured freeform starting point designs that are corrected through the third-order image degrading aberrations. The surfaces used in these starting point designs are described as a base off-axis conic that images stigmatically for the central field point, also known as a Cartesian reflector, with an aspheric departure “cap” (quartic with the aperture) added to the base off-axis conic to correct for the third-order image degrading aberrations. Once the aspheric caps are added to the surfaces, the system is then optimized using higher order freeform terms while leaving second-order terms frozen to preserve the focal length of the system during optimization. This technique is used to survey the three-mirror freeform imager solution space. Several systems that are the result of this technique are shown, with different numbers of internal images, internal pupil conjugates and folding geometries.},
keywords = {CeFO related},
pubstate = {published},
tppubtype = {proceedings}
}
Driven by the development of freeform imaging systems, we have combined several concepts and techniques from the literature to analytically generate unobscured freeform starting point designs that are corrected through the third-order image degrading aberrations. The surfaces used in these starting point designs are described as a base off-axis conic that images stigmatically for the central field point, also known as a Cartesian reflector, with an aspheric departure “cap” (quartic with the aperture) added to the base off-axis conic to correct for the third-order image degrading aberrations. Once the aspheric caps are added to the surfaces, the system is then optimized using higher order freeform terms while leaving second-order terms frozen to preserve the focal length of the system during optimization. This technique is used to survey the three-mirror freeform imager solution space. Several systems that are the result of this technique are shown, with different numbers of internal images, internal pupil conjugates and folding geometries.
Rolland, J. P.
Engineering the ultimate augmented reality display: Paths towards a digital window into the world Miscellaneous
2018.
Links | BibTeX | Tags: design, related
@misc{RollandLFW,
title = {Engineering the ultimate augmented reality display: Paths towards a digital window into the world},
author = {J. P. Rolland},
url = {http://digital.laserfocusworld.com/laserfocusworld/201806/MobilePagedArticle.action?articleId=1404125#articleId1404125},
year = {2018},
date = {2018-06-20},
issuetitle = {Laser Focus World},
volume = {June 2018},
pages = {31-34},
keywords = {design, related},
pubstate = {published},
tppubtype = {misc}
}
Dorrer, C.; Qiao, J.
Direct binary search for improved beam shaping and optical differentiation wavefront sensing Journal Article
In: Applied Optics, vol. 57, no. 29, pp. 8557-8565 , 2018.
Abstract | Links | BibTeX | Tags: CeFO related, manufacturing, related
@article{LaurenApp18,
title = {Direct binary search for improved beam shaping and optical differentiation wavefront sensing},
author = {C. Dorrer and J. Qiao},
doi = {https://doi.org/10.1364/AO.57.008557},
year = {2018},
date = {2018-06-01},
urldate = {2018-06-01},
journal = {Applied Optics},
volume = {57},
number = {29},
pages = {8557-8565 },
abstract = {Spatially dithered distributions of binary amplitude pixels are optimized using a full direct binary search, taking into account the experimental configuration for amplitude modulation of coherent waves. This design process is shown to yield a significant reduction of the noise induced by binarization and pixelation over the region of interest. We demonstrate this approach for beam shaping and optical differentiation wavefront sensing, where the region of interest is in an image plane of the pixel distribution, and in the far field of the pixel distribution, respectively. The observed reduction in error compared to a standard error diffusion algorithm is significant for both applications because it improves performance without the tighter fabrication tolerance and cost associated with smaller pixels.},
keywords = {CeFO related, manufacturing, related},
pubstate = {published},
tppubtype = {article}
}
Spatially dithered distributions of binary amplitude pixels are optimized using a full direct binary search, taking into account the experimental configuration for amplitude modulation of coherent waves. This design process is shown to yield a significant reduction of the noise induced by binarization and pixelation over the region of interest. We demonstrate this approach for beam shaping and optical differentiation wavefront sensing, where the region of interest is in an image plane of the pixel distribution, and in the far field of the pixel distribution, respectively. The observed reduction in error compared to a standard error diffusion algorithm is significant for both applications because it improves performance without the tighter fabrication tolerance and cost associated with smaller pixels.
Yao, Jianing; Anderson, Alexander; Rolland, Jannick P.
Point-cloud noncontact metrology of freeform optical surfaces Journal Article
In: Optics Express, vol. 26, no. 8, pp. 10242-10265, 2018.
Abstract | Links | BibTeX | Tags: metrology, related
@article{yao18,
title = {Point-cloud noncontact metrology of freeform optical surfaces},
author = {Jianing Yao and Alexander Anderson and Jannick P. Rolland},
url = {https://doi.org/10.1364/OE.26.010242},
doi = {10.1364/OE.26.010242},
year = {2018},
date = {2018-04-09},
journal = {Optics Express},
volume = {26},
number = {8},
pages = {10242-10265},
abstract = {In this paper, we demonstrate the development of a point-cloud metrology method for the noncontact, high resolution, high precision testing of freeform surfaces. The method leverages swept source optical coherence tomography together with a common-path setup in the sample arm configured to mitigate the axial jitter caused by scanning and environmental perturbations. The lateral x-y scanning field was also rigorously evaluated for the sampling step, linearity, straightness, and orthogonality. Based on the finely engineered system hardware, a comprehensive system model was developed capable of characterizing the vertical displacement sensitivity and lateral scanning noise. The model enables predicting the point-cloud surface-metrology uncertainty map of any freeform surface and guiding the selection of optimum experimental conditions. A system was then assembled and experimentally evaluated first with flat and spherical standards to demonstrate the measurement uncertainty. Results of measuring an Alvarez freeform surface with 400-µm peak-to-valley sag show 93 nm (< λ/14) precision and 128 nm (< λ/10) root-mean-square residual from the nominal shape. The high resolution measurements also reveal mid spatial frequency structures on the test part.},
keywords = {metrology, related},
pubstate = {published},
tppubtype = {article}
}
In this paper, we demonstrate the development of a point-cloud metrology method for the noncontact, high resolution, high precision testing of freeform surfaces. The method leverages swept source optical coherence tomography together with a common-path setup in the sample arm configured to mitigate the axial jitter caused by scanning and environmental perturbations. The lateral x-y scanning field was also rigorously evaluated for the sampling step, linearity, straightness, and orthogonality. Based on the finely engineered system hardware, a comprehensive system model was developed capable of characterizing the vertical displacement sensitivity and lateral scanning noise. The model enables predicting the point-cloud surface-metrology uncertainty map of any freeform surface and guiding the selection of optimum experimental conditions. A system was then assembled and experimentally evaluated first with flat and spherical standards to demonstrate the measurement uncertainty. Results of measuring an Alvarez freeform surface with 400-µm peak-to-valley sag show 93 nm (< λ/14) precision and 128 nm (< λ/10) root-mean-square residual from the nominal shape. The high resolution measurements also reveal mid spatial frequency structures on the test part.
Zhao, Nan; Papa, Jonathan C.; Fuerschbach, Kyle; Qiao, Yanfeng; Thompson, Kevin P.; Rolland, Jannick P.
Experimental investigation in nodal aberration theory (NAT) with a customized Ritchey-Chrétien system: third-order coma Journal Article
In: Optics Express, vol. 26, no. 7, pp. 8729-8743, 2018.
Abstract | Links | BibTeX | Tags: metrology, related
@article{nanzhao18,
title = {Experimental investigation in nodal aberration theory (NAT) with a customized Ritchey-Chrétien system: third-order coma},
author = {Nan Zhao and Jonathan C. Papa and Kyle Fuerschbach and Yanfeng Qiao and Kevin P. Thompson and Jannick P. Rolland},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-26-7-8729},
doi = {10.1364/OE.26.008729},
year = {2018},
date = {2018-04-02},
journal = {Optics Express},
volume = {26},
number = {7},
pages = {8729-8743},
abstract = {Nodal aberration theory (NAT) describes the aberration properties of optical systems without symmetry. NAT was fully described mathematically and investigated through real-ray tracing software, but an experimental investigation is yet to be realized. In this study, a two-mirror Ritchey-Chrétien telescope was designed and built, including testing of the mirrors in null configurations, for experimental investigation of NAT. A feature of this custom telescope is a high-precision hexapod that controls the secondary mirror of the telescope to purposely introduce system misalignments and quantify the introduced aberrations interferometrically. A method was developed to capture interferograms for multiple points across the field of view without moving the interferometer. A simulation result of Fringe Zernike coma was generated and analyzed to provide a direct comparison with the experimental results. A statistical analysis of the measurements was conducted to assess residual differences between simulations and experimental results. The interferograms were consistent with the simulations, thus experimentally validating NAT for third-order coma.},
keywords = {metrology, related},
pubstate = {published},
tppubtype = {article}
}
Nodal aberration theory (NAT) describes the aberration properties of optical systems without symmetry. NAT was fully described mathematically and investigated through real-ray tracing software, but an experimental investigation is yet to be realized. In this study, a two-mirror Ritchey-Chrétien telescope was designed and built, including testing of the mirrors in null configurations, for experimental investigation of NAT. A feature of this custom telescope is a high-precision hexapod that controls the secondary mirror of the telescope to purposely introduce system misalignments and quantify the introduced aberrations interferometrically. A method was developed to capture interferograms for multiple points across the field of view without moving the interferometer. A simulation result of Fringe Zernike coma was generated and analyzed to provide a direct comparison with the experimental results. A statistical analysis of the measurements was conducted to assess residual differences between simulations and experimental results. The interferograms were consistent with the simulations, thus experimentally validating NAT for third-order coma.
Taylor, L.; Qiao, J.
Predicting Ablation-Cooled Gigahertz Ultrafast Laser Processing via Integrated Modeling Conference
ICALEO 37th International Congress on Applications of Lasers & Electro-Optics, Paper LMF 6, 2018.
BibTeX | Tags: CeFO related, manufacturing
@conference{LaurenICALEO18,
title = {Predicting Ablation-Cooled Gigahertz Ultrafast Laser Processing via Integrated Modeling},
author = {L. Taylor and J. Qiao},
year = {2018},
date = {2018-03-14},
booktitle = {ICALEO 37th International Congress on Applications of Lasers & Electro-Optics, Paper LMF 6},
keywords = {CeFO related, manufacturing},
pubstate = {published},
tppubtype = {conference}
}
Taylor, L. L.; Scott, R. E.; Qiao, J.
Integrating two-temperature and classical heat accumulation models to predict femtosecond laser processing of silicon Journal Article
In: Optical Materials Express, vol. 8, no. 3, pp. 648-658, 2018.
Abstract | Links | BibTeX | Tags: CeFO related, manufacturing
@article{QiaoOMEX18,
title = {Integrating two-temperature and classical heat accumulation models to predict femtosecond laser processing of silicon},
author = {L. L. Taylor and R. E. Scott and J. Qiao },
doi = {https://doi.org/10.1364/OME.8.000648},
year = {2018},
date = {2018-03-01},
urldate = {2018-03-01},
journal = {Optical Materials Express},
volume = {8},
number = {3},
pages = {648-658},
abstract = {A robust, computationally efficient modeling method describing multi-pulse femtosecond laser-material interaction is required to determine the optimal laser parameters to control and differentiate non-thermal ablation and heat accumulation processes for surface structuring and laser welding applications. We establish a three-dimensional, two-temperature model (TTM) and a heat-accumulation model based on classical heat generation and conduction equations to evaluate their efficacy and efficiency in simulating non-thermal ablation and heat accumulation during multi-pulse femtosecond laser processing of silicon. Only the TTM is capable of accurately predicting the laser fluences required to achieve non-thermal ablation, which is experimentally validated. Both the TTM and the classical heat accumulation model can predict heat accumulation. The TTM can accurately predict heat accumulation, but requires lengthy simulation times on the order of several hours. The classical heat accumulation model consistently predicts heat accumulation with the TTM and is time efficient, but is case specific to interaction parameters, requiring input of an experimentally-determined absorption coefficient. For the first time to our knowledge, an integrated modeling method is devised to accurately and efficiently simulate laser-processing-induced heat accumulation by using the TTM to determine an absorption coefficient to feed back to the heat accumulation model to extend it to the general case. This integrated modeling method enables the accurate prediction of heat accumulation with simulation times on the order of a minute per pulse, defining a path to determine laser parameters to control heat accumulation for specific processing applications.},
keywords = {CeFO related, manufacturing},
pubstate = {published},
tppubtype = {article}
}
A robust, computationally efficient modeling method describing multi-pulse femtosecond laser-material interaction is required to determine the optimal laser parameters to control and differentiate non-thermal ablation and heat accumulation processes for surface structuring and laser welding applications. We establish a three-dimensional, two-temperature model (TTM) and a heat-accumulation model based on classical heat generation and conduction equations to evaluate their efficacy and efficiency in simulating non-thermal ablation and heat accumulation during multi-pulse femtosecond laser processing of silicon. Only the TTM is capable of accurately predicting the laser fluences required to achieve non-thermal ablation, which is experimentally validated. Both the TTM and the classical heat accumulation model can predict heat accumulation. The TTM can accurately predict heat accumulation, but requires lengthy simulation times on the order of several hours. The classical heat accumulation model consistently predicts heat accumulation with the TTM and is time efficient, but is case specific to interaction parameters, requiring input of an experimentally-determined absorption coefficient. For the first time to our knowledge, an integrated modeling method is devised to accurately and efficiently simulate laser-processing-induced heat accumulation by using the TTM to determine an absorption coefficient to feed back to the heat accumulation model to extend it to the general case. This integrated modeling method enables the accurate prediction of heat accumulation with simulation times on the order of a minute per pulse, defining a path to determine laser parameters to control heat accumulation for specific processing applications.
2017
Papa, J.; Howard, J. M.; Rolland, J. P.
Four-Mirror Freeform Design Conference
Mirror Tech/SBIR/STTR Workshop 2017, 2017.
Links | BibTeX | Tags: CeFO related, design, related
@conference{Papa_nasa,
title = {Four-Mirror Freeform Design},
author = {J. Papa and J. M. Howard and J. P. Rolland},
url = {https://spie.org/Documents/ConferencesExhibitions/Tech-Days-2017-Presentations-DRAFT.pdf},
year = {2017},
date = {2017-11-15},
booktitle = {Mirror Tech/SBIR/STTR Workshop 2017},
keywords = {CeFO related, design, related},
pubstate = {published},
tppubtype = {conference}
}
Lambropoulos, John C.
Twyman effects in thin curved optics Proceeding
SPIE, vol. SPIE Vol 10448, no. 104480V (2017), 2017.
Abstract | Links | BibTeX | Tags: CeFO related, metrology
@proceedings{Lambropoulos172,
title = {Twyman effects in thin curved optics},
author = {John C. Lambropoulos},
editor = {Julie L. Bentley; Sebastian Stoebenau},
url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10448/104480V/Twyman-effects-in-thin-curved-optics/10.1117/12.2279833.short},
year = {2017},
date = {2017-10-20},
volume = {SPIE Vol 10448},
number = {104480V (2017)},
publisher = {SPIE},
series = {Optifab},
abstract = {The Twyman effect refers to the fact that, when a thin optical plate has one side ground, the plate bends with the ground side becoming convex, i.e. as if the ground side is in a residual compressive stress. Such deformation often shows up as “power” on form measurements of the other (usually polished) plate surface. For thin flat optics, Twyman effects become important at aspect ratios of 1:25 or thinner. In this case, the optic bends throughout its surface with a constant curvature, i.e. bending extends over the whole surface. Here we discuss Twyman effects for mildly or highly curved thin axisymmetric optics such as cylinders, spheres, and shallow lenses or mirrors. We also outline extensions to more complex geometries, such as ogives. We show that the deformation in thin curved optics is significantly different from flat plates: In curved optics, deformation consists of a simple stretching contribution, valid over the largest portion of the optic, plus a complex, spatially-dependent bending contribution in a boundary layer, valid near the free edges of the optic. },
keywords = {CeFO related, metrology},
pubstate = {published},
tppubtype = {proceedings}
}
The Twyman effect refers to the fact that, when a thin optical plate has one side ground, the plate bends with the ground side becoming convex, i.e. as if the ground side is in a residual compressive stress. Such deformation often shows up as “power” on form measurements of the other (usually polished) plate surface. For thin flat optics, Twyman effects become important at aspect ratios of 1:25 or thinner. In this case, the optic bends throughout its surface with a constant curvature, i.e. bending extends over the whole surface. Here we discuss Twyman effects for mildly or highly curved thin axisymmetric optics such as cylinders, spheres, and shallow lenses or mirrors. We also outline extensions to more complex geometries, such as ogives. We show that the deformation in thin curved optics is significantly different from flat plates: In curved optics, deformation consists of a simple stretching contribution, valid over the largest portion of the optic, plus a complex, spatially-dependent bending contribution in a boundary layer, valid near the free edges of the optic.
Papa, J.; Howard, J. M.; Rolland, J. P.
Starting Point Designs for Freeform Four-Mirror Systems Conference
Proceedings of the International Optical Design Conference 2017, Optical Society of America, 2017, ISBN: 978-1-943580-31-6.
Abstract | Links | BibTeX | Tags: design, related
@conference{PapaIODC17,
title = {Starting Point Designs for Freeform Four-Mirror Systems},
author = {J. Papa and J. M. Howard and J. P. Rolland},
url = {https://doi.org/10.1364/IODC.2017.ITu2A.4},
doi = {10.1364/IODC.2017.ITu2A.4},
isbn = {978-1-943580-31-6},
year = {2017},
date = {2017-07-13},
urldate = {2017-07-13},
booktitle = {Proceedings of the International Optical Design Conference 2017},
publisher = {Optical Society of America},
abstract = {Driven by the development of freeform four-mirror solutions, we compare analytical methods to generate starting point designs with various states of correction, surface types, symmetry, and obscuration. The advantages and disadvantages of each are examined.},
keywords = {design, related},
pubstate = {published},
tppubtype = {conference}
}
Driven by the development of freeform four-mirror solutions, we compare analytical methods to generate starting point designs with various states of correction, surface types, symmetry, and obscuration. The advantages and disadvantages of each are examined.
Shultz, J. A.; Davies, M.; Suleski, T. J.
Simplified Tolerancing of Alignment Errors in Dynamic Freeform Optical Systems Conference
Freeform 2017 (Freeform, IODC, OFT), Optical Society of America, 2017.
Abstract | Links | BibTeX | Tags: assembly, related
@conference{Suleski17_1,
title = {Simplified Tolerancing of Alignment Errors in Dynamic Freeform Optical Systems},
author = {J. A. Shultz and M. Davies and T. J. Suleski},
url = {https://doi.org/10.1364/FREEFORM.2017.JTh1C.3},
doi = {10.1364/FREEFORM.2017.JTh1C.3},
year = {2017},
date = {2017-07-13},
booktitle = {Freeform 2017 (Freeform, IODC, OFT)},
publisher = {Optical Society of America},
abstract = {We discuss and demonstrate approaches for analyzing and quantifying the sensitivity of dynamic freeform optical systems to positioning errors, and the resulting impacts on optical performance. Imaging and non-imaging examples are considered.},
keywords = {assembly, related},
pubstate = {published},
tppubtype = {conference}
}
We discuss and demonstrate approaches for analyzing and quantifying the sensitivity of dynamic freeform optical systems to positioning errors, and the resulting impacts on optical performance. Imaging and non-imaging examples are considered.
Shultz, J. A.; Suleski, T. J.
Design of a Variable Toric Lens Using Laterally Shifted Freeform Elements Conference
Freeform 2017 (Freeform, IODC, OFT), Optical Society of America, 2017.
Abstract | Links | BibTeX | Tags: design, related
@conference{Suleski17_2,
title = {Design of a Variable Toric Lens Using Laterally Shifted Freeform Elements},
author = {J. A. Shultz and T. J. Suleski },
doi = {https://doi.org/10.1364/FREEFORM.2017.JW2C.2},
year = {2017},
date = {2017-07-13},
urldate = {2017-07-13},
booktitle = {Freeform 2017 (Freeform, IODC, OFT)},
publisher = {Optical Society of America},
abstract = {We present a design process for a variable lens pair where the x and y focal lengths are varied independently of each other using laterally shifted freeform surfaces. Examples are presented.},
keywords = {design, related},
pubstate = {published},
tppubtype = {conference}
}
We present a design process for a variable lens pair where the x and y focal lengths are varied independently of each other using laterally shifted freeform surfaces. Examples are presented.
Liang, Kevin; Alonso, Miguel A.
MTF as the Fourier Transform of a Pupil-Difference Probability Density Presentation
09.07.2017, ISBN: 978-1-943580-31-6, (Freeform Optics 2017 Denver, Colorado United States 9–13 July 2017).
Abstract | Links | BibTeX | Tags: CeFO design
@misc{Alonso2017,
title = {MTF as the Fourier Transform of a Pupil-Difference Probability Density},
author = {Kevin Liang and Miguel A. Alonso},
editor = {Optical Society of America},
url = {https://doi.org/10.1364/FREEFORM.2017.JTu1C.4},
doi = {https://doi.org/10.1364/FREEFORM.2017.JTu1C.4},
isbn = { 978-1-943580-31-6},
year = {2017},
date = {2017-07-09},
abstract = {We develop the theory for calculating the effects of mid-spatial frequency structures on the modulation transfer function through the Fourier transform of a pupil-difference probability density function. Its implementation is shown for several periodic groove.},
note = {Freeform Optics 2017
Denver, Colorado United States
9–13 July 2017},
keywords = {CeFO design},
pubstate = {published},
tppubtype = {presentation}
}
We develop the theory for calculating the effects of mid-spatial frequency structures on the modulation transfer function through the Fourier transform of a pupil-difference probability density function. Its implementation is shown for several periodic groove.
Qiao, J.; Dorrer, C.
Measuring wavefront by optical differentiation with binary pixelated filters Proceeding
Optical Society of America, Imaging and Applied Optics, 2017.
Abstract | Links | BibTeX | Tags: CeFO related, manufacturing
@proceedings{QiaoImgApplOpt17,
title = {Measuring wavefront by optical differentiation with binary pixelated filters},
author = {J. Qiao and C. Dorrer},
url = {http://www.osapublishing.org/abstract.cfm?URI=ISA-2017-ITu4E.3},
doi = {10.1364/ISA.2017.ITu4E.3},
year = {2017},
date = {2017-06-26},
urldate = {2017-06-26},
pages = {ITu4E.3},
publisher = {Optical Society of America, Imaging and Applied Optics},
abstract = {We review the performance and applications of an optical differentiation wavefront sensor based on binary pixelated filters that synthesize a continuous linear field transmission profile yielding the wavefront slope in the transmission gradient direction.},
keywords = {CeFO related, manufacturing},
pubstate = {published},
tppubtype = {proceedings}
}
We review the performance and applications of an optical differentiation wavefront sensor based on binary pixelated filters that synthesize a continuous linear field transmission profile yielding the wavefront slope in the transmission gradient direction.
Scott, R. E.; Taylor, L. L.; Qiao, J.
Conference on Lasers and Electro-Optics (CLEO), Optical Society of America, 2017.
Abstract | Links | BibTeX | Tags: CeFO related, manufacturing
@proceedings{QiaoCLEO17,
title = {Comparison of Two-Temperature and Thermal Models for Prediction of the Optimal Femtosecond Laser-Material Processing of Silicon},
author = {R. E. Scott and L. L. Taylor and J. Qiao},
url = {http://www.osapublishing.org/abstract.cfm?URI=CLEO_AT-2017-ATu4C.5},
doi = {10.1364/CLEO_AT.2017.ATu4C.5},
year = {2017},
date = {2017-05-14},
urldate = {2017-05-14},
pages = {ATu4C.5},
publisher = {Conference on Lasers and Electro-Optics (CLEO), Optical Society of America},
abstract = {A thermal and a two-temperature model (TTM) describing femtosecond laser-material interactions are compared. Both models accurately describe thermal response of silicon to multi-pulse irradiations, while the TTM distinguishes between thermal and non-thermal regimes.},
keywords = {CeFO related, manufacturing},
pubstate = {published},
tppubtype = {proceedings}
}
A thermal and a two-temperature model (TTM) describing femtosecond laser-material interactions are compared. Both models accurately describe thermal response of silicon to multi-pulse irradiations, while the TTM distinguishes between thermal and non-thermal regimes.
HIPPOLYTE DOURDENT ANTHONY VELLA, LUKAS NOVOTNY; ALONSO, MIGUEL A.
Birefringent masks that are optimal for generating bottle fields Journal Article
In: Optics Express, vol. 25, no. 8, pp. 9318-9332, 2017.
Abstract | Links | BibTeX | Tags: design, related
@article{AlonsoVella2017,
title = {Birefringent masks that are optimal for generating bottle fields},
author = {ANTHONY VELLA, HIPPOLYTE DOURDENT, LUKAS NOVOTNY, AND MIGUEL A. ALONSO},
editor = {OSA},
doi = {https://doi.org/10.1364/OE.25.009318},
year = {2017},
date = {2017-04-17},
journal = {Optics Express},
volume = {25},
number = {8},
pages = {9318-9332},
abstract = {An optical bottle field containing a three-dimensional intensity null at the focal point can be generated by placing a spatially inhomogeneous birefringent mask at the pupil of an aplanatic high-NA focusing system. We derive the optimal birefringence distribution for which a uniformly polarized input beam is converted into a bottle field with the sharpest possible null in intensity. We show that a stress engineered optical (SEO) window, which has a radially varying retardance, followed by a half-wave plate, performs nearly as well as the optimal solution. Experimental results corroborate that an SEO element can be used to generate a bottle field.},
keywords = {design, related},
pubstate = {published},
tppubtype = {article}
}
An optical bottle field containing a three-dimensional intensity null at the focal point can be generated by placing a spatially inhomogeneous birefringent mask at the pupil of an aplanatic high-NA focusing system. We derive the optimal birefringence distribution for which a uniformly polarized input beam is converted into a bottle field with the sharpest possible null in intensity. We show that a stress engineered optical (SEO) window, which has a radially varying retardance, followed by a half-wave plate, performs nearly as well as the optimal solution. Experimental results corroborate that an SEO element can be used to generate a bottle field.
Shultz, J. A.; Smilie, P. J.; Davies, M. A.; Suleski, T. J.
Optomechanical tolerancing of dynamic freeform optical systems Conference
Proceedings ASPE/ASPEN Spring Topical Meeting: Manufacture and Metrology of Structured and Freeform Surfaces for Functional Applications, ASPE/ASPEN, 2017, (Proceedings of ASPE/ASPEN Spring Topical Meeting).
BibTeX | Tags: assembly, related
@conference{Suleski17_4,
title = {Optomechanical tolerancing of dynamic freeform optical systems},
author = {J. A. Shultz and P. J. Smilie and M. A. Davies and T. J. Suleski},
year = {2017},
date = {2017-03-16},
booktitle = {Proceedings ASPE/ASPEN Spring Topical Meeting: Manufacture and Metrology of Structured and Freeform Surfaces for Functional Applications},
publisher = {ASPE/ASPEN},
note = {Proceedings of ASPE/ASPEN Spring Topical Meeting},
keywords = {assembly, related},
pubstate = {published},
tppubtype = {conference}
}
2016
Xu, Di; Yao, Jianing; Zhao, Nan; Rolland, Jannick P.
Optical Society of America, 2016, ISBN: 978-1-943580-19-4, (The CEFO project relevant portions were not included in the proceeding but were presented directly at the conference. Presentation slides are available upon request. ).
Abstract | Links | BibTeX | Tags: related, testing
@conference{Xu2016,
title = {Scanning Customized Swept-source Optical Coherence Tomography (SS-OCT) for the Metrology of Freeform Optical Surfaces},
author = {Di Xu and Jianing Yao and Nan Zhao and Jannick P. Rolland},
url = {https://doi.org/10.1364/FIO.2016.FW5H.6},
doi = {10.1364/FIO.2016.FW5H.6},
isbn = {978-1-943580-19-4},
year = {2016},
date = {2016-10-17},
urldate = {2016-10-17},
publisher = {Optical Society of America},
abstract = {A high-precision SS-OCT system with custom scanning configuration was developed for the point cloud metrology of freeform optical surfaces. Capabilities were demonstrated on an Alvarez surface and a measurement precision of λ/20 was achieved.},
note = {The CEFO project relevant portions were not included in the proceeding but were presented directly at the conference. Presentation slides are available upon request. },
keywords = {related, testing},
pubstate = {published},
tppubtype = {conference}
}
A high-precision SS-OCT system with custom scanning configuration was developed for the point cloud metrology of freeform optical surfaces. Capabilities were demonstrated on an Alvarez surface and a measurement precision of λ/20 was achieved.
Moore, D. B.; Fienup, J. R.
Ptychography for optical metrology with limited translation knowledge Journal Article
In: Applied Optics, vol. 55, no. 17, pp. 4596-4610, 2016.
Abstract | Links | BibTeX | Tags: related, testing
@article{Fienup16,
title = {Ptychography for optical metrology with limited translation knowledge},
author = {Moore, D. B. and J. R. Fienup},
url = {https://www.osapublishing.org/ao/abstract.cfm?uri=ao-55-17-4596},
doi = {https://doi.org/10.1364/AO.55.004596},
year = {2016},
date = {2016-06-07},
urldate = {2016-06-07},
journal = {Applied Optics},
volume = {55},
number = {17},
pages = {4596-4610},
abstract = {We introduce unknown-transverse translation diversity phase retrieval: a ptychographic algorithm for optical metrology when a subaperture is translating through a plane conjugate to the exit pupil in a very poorly known fashion. The algorithm estimates the direction of translation and the distance traveled by the subaperture from one point spread function (PSF) to the next. It also estimates unknown point target motion and rotations of the subaperture between PSF acquisitions from the PSF data.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {article}
}
We introduce unknown-transverse translation diversity phase retrieval: a ptychographic algorithm for optical metrology when a subaperture is translating through a plane conjugate to the exit pupil in a very poorly known fashion. The algorithm estimates the direction of translation and the distance traveled by the subaperture from one point spread function (PSF) to the next. It also estimates unknown point target motion and rotations of the subaperture between PSF acquisitions from the PSF data.
Salzman, S.
Optimal magnetorheological fluid for finishing of CVD zinc sulfide PhD Thesis
University of Rochester, 2016.
Abstract | Links | BibTeX | Tags: manufacturing, related
@phdthesis{Salzman2016,
title = {Optimal magnetorheological fluid for finishing of CVD zinc sulfide},
author = {Salzman, S.},
url = {https://www.lle.rochester.edu/media/publications/documents/theses/Salzman.pdf},
year = {2016},
date = {2016-06-01},
urldate = {2016-06-01},
address = {Department of mechanical Engineering},
school = {University of Rochester},
abstract = {Magnetorheological finishing (MRF) of polycrystalline, chemical-vapor-deposited zinc sulfide (ZnS) optics tends to leave visible surface artifacts known as “pebbles”. These artifacts are a direct result of the material’s inner structure that consists of cone-like features that grow larger (up to a few millimeters in size) as deposition takes place, and manifest on the top deposited surface as pebbles. Polishing the pebble features from a CVD ZnS substrate to a flat surface and smooth to below 10 nm root-mean-square) is challenging, especially for a non-destructive polishing process such as MRF.
This work explores ways to improve the surface finish of CVD ZnS processed with MRF through modification of the magnetorheological (MR) fluid’s properties. A materials science approach is presented to define the anisotropy of CVD ZnS through a combination of chemical and mechanical experiments and theoretical predictions. Magnetorheological finishing experiments with single crystal samples of ZnS, whose cuts and orientations represent most of the facets known to occur in the polycrystalline CVD ZnS, were performed to explore the influence of material anisotropy on the material removal rate during MRF. By adjusting fluid’s viscosity, abrasive type concentration, and fluid’s pH to find the chemo-mechanical conditions that equalize removal rates among all single crystal facets during MRF, we came up with an optimized, novel MR formulation to polish CVD ZnS without degrading the surface finish of the optic.},
type = {related},
keywords = {manufacturing, related},
pubstate = {published},
tppubtype = {phdthesis}
}
Magnetorheological finishing (MRF) of polycrystalline, chemical-vapor-deposited zinc sulfide (ZnS) optics tends to leave visible surface artifacts known as “pebbles”. These artifacts are a direct result of the material’s inner structure that consists of cone-like features that grow larger (up to a few millimeters in size) as deposition takes place, and manifest on the top deposited surface as pebbles. Polishing the pebble features from a CVD ZnS substrate to a flat surface and smooth to below 10 nm root-mean-square) is challenging, especially for a non-destructive polishing process such as MRF.
This work explores ways to improve the surface finish of CVD ZnS processed with MRF through modification of the magnetorheological (MR) fluid’s properties. A materials science approach is presented to define the anisotropy of CVD ZnS through a combination of chemical and mechanical experiments and theoretical predictions. Magnetorheological finishing experiments with single crystal samples of ZnS, whose cuts and orientations represent most of the facets known to occur in the polycrystalline CVD ZnS, were performed to explore the influence of material anisotropy on the material removal rate during MRF. By adjusting fluid’s viscosity, abrasive type concentration, and fluid’s pH to find the chemo-mechanical conditions that equalize removal rates among all single crystal facets during MRF, we came up with an optimized, novel MR formulation to polish CVD ZnS without degrading the surface finish of the optic.
This work explores ways to improve the surface finish of CVD ZnS processed with MRF through modification of the magnetorheological (MR) fluid’s properties. A materials science approach is presented to define the anisotropy of CVD ZnS through a combination of chemical and mechanical experiments and theoretical predictions. Magnetorheological finishing experiments with single crystal samples of ZnS, whose cuts and orientations represent most of the facets known to occur in the polycrystalline CVD ZnS, were performed to explore the influence of material anisotropy on the material removal rate during MRF. By adjusting fluid’s viscosity, abrasive type concentration, and fluid’s pH to find the chemo-mechanical conditions that equalize removal rates among all single crystal facets during MRF, we came up with an optimized, novel MR formulation to polish CVD ZnS without degrading the surface finish of the optic.
Shahinian, H.; Cherukuri, H.; Mullany, B.
An Evaluation of Fiber-Based Tools for Glass Polishing Using Experimental and Computational Approaches Journal Article
In: Applied Optics, vol. 45, no. 16, pp. 4307-4316, 2016.
Abstract | Links | BibTeX | Tags: CeFO manufacturing
@article{Shahinian16,
title = {An Evaluation of Fiber-Based Tools for Glass Polishing Using Experimental and Computational Approaches},
author = {Shahinian, H. and H. Cherukuri and B. Mullany},
doi = {https://doi.org/10.1364/AO.55.004307},
year = {2016},
date = {2016-06-01},
urldate = {2016-06-01},
journal = {Applied Optics},
volume = {45},
number = {16},
pages = {4307-4316},
abstract = {Polymeric pad or pitch-based tools combined with loose abrasive slurries are typically used in the polishing of optical materials. In this paper, the potential of fiber-based tools to both remove material and provide high quality surface finishes on BK7 glass is explored. The potential advantage of fiber-based tools over traditional tools is their inherent compliance, which could accommodate varying workpiece surface curvatures as found in aspheres and freeforms. To evaluate the new tools, both experimental and finite element (FE) modeling approaches were taken. A FE model consisting of a single fiber engaged with the workpiece surface was used to estimate the shape and magnitude of the pressure distribution exerted by the fiber on the workpiece surface. Two different tool configurations, yielding two different Fes, predicted pressure distributions, were used to polish BK7 samples, and the material removal profiles were interferometrically measured. The resulting profiles and the predicted pressure distributions share the same v-shape. While differences in scale exist between the experimental and FE-predicted profiles, the tool generating higher material removal had the greater predicted pressure distribution, thus demonstrating the ability of the FE model to provide insights into tool design. Additional testing was conducted to determine if the tool’s removal rate can be predicted by Preston’s equation. Initial results indicate the equation is valid within the range of parameters tested. The surface roughness of BK7 samples processed by this tool was measured and some deterioration on the Sq value was noted; the surface roughness increased from 1.89 to 3.66 nm Sq. Over several hours of continuous use, the load applied by the fibers decays in a repeatable manner, and little wear was observed on the fibers after 5.33 h of polishing.},
keywords = {CeFO manufacturing},
pubstate = {published},
tppubtype = {article}
}
Polymeric pad or pitch-based tools combined with loose abrasive slurries are typically used in the polishing of optical materials. In this paper, the potential of fiber-based tools to both remove material and provide high quality surface finishes on BK7 glass is explored. The potential advantage of fiber-based tools over traditional tools is their inherent compliance, which could accommodate varying workpiece surface curvatures as found in aspheres and freeforms. To evaluate the new tools, both experimental and finite element (FE) modeling approaches were taken. A FE model consisting of a single fiber engaged with the workpiece surface was used to estimate the shape and magnitude of the pressure distribution exerted by the fiber on the workpiece surface. Two different tool configurations, yielding two different Fes, predicted pressure distributions, were used to polish BK7 samples, and the material removal profiles were interferometrically measured. The resulting profiles and the predicted pressure distributions share the same v-shape. While differences in scale exist between the experimental and FE-predicted profiles, the tool generating higher material removal had the greater predicted pressure distribution, thus demonstrating the ability of the FE model to provide insights into tool design. Additional testing was conducted to determine if the tool’s removal rate can be predicted by Preston’s equation. Initial results indicate the equation is valid within the range of parameters tested. The surface roughness of BK7 samples processed by this tool was measured and some deterioration on the Sq value was noted; the surface roughness increased from 1.89 to 3.66 nm Sq. Over several hours of continuous use, the load applied by the fibers decays in a repeatable manner, and little wear was observed on the fibers after 5.33 h of polishing.
Huang, J.; Hindman, H. B.; Rolland, J. P.
In vivo thickness dynamics measurement of tear film lipid and aqueous layers with optical coherence tomography and maximum-likelihood estimation Journal Article
In: Optics Letters, vol. 41, no. 9, pp. 1981-1984 , 2016.
Abstract | Links | BibTeX | Tags: related, testing
@article{Huang16,
title = {In vivo thickness dynamics measurement of tear film lipid and aqueous layers with optical coherence tomography and maximum-likelihood estimation},
author = {Huang, J. and H. B. Hindman and J. P. Rolland},
doi = {https://doi.org/10.1364/OL.41.001981},
year = {2016},
date = {2016-04-15},
urldate = {2016-04-15},
journal = {Optics Letters},
volume = {41},
number = {9},
pages = {1981-1984 },
abstract = {Dry eye disease (DED) is a common ophthalmic condition that is characterized by tear film instability and leads to ocular surface discomfort and visual disturbance. Advancements in the understanding and management of this condition have been limited by our ability to study the tear film secondary to its thin structure and dynamic nature. Here, we report a technique to simultaneously estimate the thickness of both the lipid and aqueous layers of the tear film in vivo using optical coherence tomography and maximum-likelihood estimation. After a blink, the lipid layer was rapidly thickened at an average rate of 10 nm/s
over the first 2.5 s before stabilizing, whereas the aqueous layer continued thinning at an average rate of 0.29 μm/s
of the 10 s blink cycle. Further development of this tear film imaging technique may allow for the elucidation of events that trigger tear film instability in DED.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {article}
}
Dry eye disease (DED) is a common ophthalmic condition that is characterized by tear film instability and leads to ocular surface discomfort and visual disturbance. Advancements in the understanding and management of this condition have been limited by our ability to study the tear film secondary to its thin structure and dynamic nature. Here, we report a technique to simultaneously estimate the thickness of both the lipid and aqueous layers of the tear film in vivo using optical coherence tomography and maximum-likelihood estimation. After a blink, the lipid layer was rapidly thickened at an average rate of 10 nm/s
over the first 2.5 s before stabilizing, whereas the aqueous layer continued thinning at an average rate of 0.29 μm/s
of the 10 s blink cycle. Further development of this tear film imaging technique may allow for the elucidation of events that trigger tear film instability in DED.
over the first 2.5 s before stabilizing, whereas the aqueous layer continued thinning at an average rate of 0.29 μm/s
of the 10 s blink cycle. Further development of this tear film imaging technique may allow for the elucidation of events that trigger tear film instability in DED.
Moore, D. B.; Fienup, J. R.
Subaperture translation estimation accuracy in transverse-translation diversity phase retrieval Journal Article
In: Applied Optics, vol. 55, no. 10, pp. 2526-2536, 2016.
Abstract | Links | BibTeX | Tags: related, testing
@article{ao-55-10-2526.bib,
title = {Subaperture translation estimation accuracy in transverse-translation diversity phase retrieval},
author = {Moore, D.B. and J.R. Fienup},
url = {https://www.osapublishing.org/ao/abstract.cfm?uri=ao-55-10-2526&origin=search},
doi = {10.1364/AO.55.002526},
year = {2016},
date = {2016-03-22},
journal = {Applied Optics},
volume = {55},
number = {10},
pages = {2526-2536},
abstract = {For optical metrology by transverse translation diversity phase retrieval (or ptychography), information theoretic limits on the ability to estimate subaperture translation, essential for accurate metrology, are assessed as a function of the optical aberrations of the system being measured. Special attention is given to the case that an unknown linear phase aberration, or equivalent detector or target motion, is present that varies with each point spread function in the measured data.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {article}
}
For optical metrology by transverse translation diversity phase retrieval (or ptychography), information theoretic limits on the ability to estimate subaperture translation, essential for accurate metrology, are assessed as a function of the optical aberrations of the system being measured. Special attention is given to the case that an unknown linear phase aberration, or equivalent detector or target motion, is present that varies with each point spread function in the measured data.
Mehrotra, K.
Nano-mechanics of Optical Structures for High Laser-Damage Threshold Application PhD Thesis
University of Rochester, 2016.
Abstract | Links | BibTeX | Tags: related, testing
@phdthesis{Mehrotra2016,
title = {Nano-mechanics of Optical Structures for High Laser-Damage Threshold Application},
author = {Mehrotra, K.},
url = {https://www.lle.rochester.edu/media/publications/documents/theses/Mehrotra.pdf},
year = {2016},
date = {2016-01-13},
urldate = {2016-01-13},
address = {Department of Mechanical Engineering},
school = {University of Rochester},
abstract = {Nano-structured optical materials such as amorphous silica diffraction gratings on multilayer
dielectric (MLD) thin films are critical components and performance enhancers in high-power
laser applications such as in inertial confinement fusion experiments. We use nano-indentation,
electron microscopy and finite-element (2D and 3D) simulations to measure and observe the
nano-mechanical material properties (elastic, plastic, and fracture) of nm-level features along
with their associated defects in important optical components that include single layer and multilayer
oxide films, and optical diffraction gratings. Our work reveals that elasticity, ductility and
fracture at the nm-level can be studied separately, in contrast to micromechanical deformation;
that SEM plays an important role in identifying relevant features; that in addition to
characterization, nanoindentation may be useful as a diagnostic tool; and that numerical
simulations naturally complement the experimental nano-mechanics to model the complex nmlevel
response of optical nanostructures.},
type = {related},
keywords = {related, testing},
pubstate = {published},
tppubtype = {phdthesis}
}
Nano-structured optical materials such as amorphous silica diffraction gratings on multilayer
dielectric (MLD) thin films are critical components and performance enhancers in high-power
laser applications such as in inertial confinement fusion experiments. We use nano-indentation,
electron microscopy and finite-element (2D and 3D) simulations to measure and observe the
nano-mechanical material properties (elastic, plastic, and fracture) of nm-level features along
with their associated defects in important optical components that include single layer and multilayer
oxide films, and optical diffraction gratings. Our work reveals that elasticity, ductility and
fracture at the nm-level can be studied separately, in contrast to micromechanical deformation;
that SEM plays an important role in identifying relevant features; that in addition to
characterization, nanoindentation may be useful as a diagnostic tool; and that numerical
simulations naturally complement the experimental nano-mechanics to model the complex nmlevel
response of optical nanostructures.
dielectric (MLD) thin films are critical components and performance enhancers in high-power
laser applications such as in inertial confinement fusion experiments. We use nano-indentation,
electron microscopy and finite-element (2D and 3D) simulations to measure and observe the
nano-mechanical material properties (elastic, plastic, and fracture) of nm-level features along
with their associated defects in important optical components that include single layer and multilayer
oxide films, and optical diffraction gratings. Our work reveals that elasticity, ductility and
fracture at the nm-level can be studied separately, in contrast to micromechanical deformation;
that SEM plays an important role in identifying relevant features; that in addition to
characterization, nanoindentation may be useful as a diagnostic tool; and that numerical
simulations naturally complement the experimental nano-mechanics to model the complex nmlevel
response of optical nanostructures.
Yao, J.; Thompson, K.; Ma, B.; Rolland, J. P.
Volumetric rendering and metrology of spherical gradient refractive index lens imaged by angular scan optical coherence tomography system Journal Article
In: Optics Express, vol. 24, no. 17, pp. 19388-19404, 2016.
Abstract | Links | BibTeX | Tags: related, testing
@article{YAO2016,
title = {Volumetric rendering and metrology of spherical gradient refractive index lens imaged by angular scan optical coherence tomography system},
author = {Yao, J. and K. Thompson and B. Ma and J. P. Rolland},
url = {https://centerfreeformoptics.org/wp-content/uploads/2017/01/oe-24-17-19388-1.pdf, Full paper},
doi = {10.1364/OE.24.019388 },
year = {2016},
date = {2016-00-00},
journal = {Optics Express},
volume = {24},
number = {17},
pages = {19388-19404},
abstract = {In this paper, we develop the methodology, including the refraction correction,
geometrical thickness correction, coordinate transformation, and layer segmentation
algorithms, for 3D rendering and metrology of a layered spherical gradient refractive index
(S-GRIN) lens based on the imaging data collected by an angular scan optical coherence
tomography (OCT) system. The 3D mapping and rendering enables direct 3D visualization
and internal defect inspection of the lens. The metrology provides assessment of the surface
geometry, the lens thickness, the radii of curvature of the internal layer interfaces, and the
misalignment of the internal S-GRIN distribution with respect to the lens surface. The OCT
metrology results identify the manufacturing defects, and enable targeted process
development for optimizing the manufacturing parameters. The newly fabricated S-GRIN
lenses show up to a 7x spherical aberration reduction that allows a significantly increased
utilizable effective aperture.
© 2016 Optical Society of America
OCIS codes: (120.0120) Instrumentation, measurement, and metrology; (110.4500) Optical coherence tomography;
(120.4630) Optical inspection; (110.0110) Imaging systems. },
keywords = {related, testing},
pubstate = {published},
tppubtype = {article}
}
In this paper, we develop the methodology, including the refraction correction,
geometrical thickness correction, coordinate transformation, and layer segmentation
algorithms, for 3D rendering and metrology of a layered spherical gradient refractive index
(S-GRIN) lens based on the imaging data collected by an angular scan optical coherence
tomography (OCT) system. The 3D mapping and rendering enables direct 3D visualization
and internal defect inspection of the lens. The metrology provides assessment of the surface
geometry, the lens thickness, the radii of curvature of the internal layer interfaces, and the
misalignment of the internal S-GRIN distribution with respect to the lens surface. The OCT
metrology results identify the manufacturing defects, and enable targeted process
development for optimizing the manufacturing parameters. The newly fabricated S-GRIN
lenses show up to a 7x spherical aberration reduction that allows a significantly increased
utilizable effective aperture.
© 2016 Optical Society of America
OCIS codes: (120.0120) Instrumentation, measurement, and metrology; (110.4500) Optical coherence tomography;
(120.4630) Optical inspection; (110.0110) Imaging systems.
geometrical thickness correction, coordinate transformation, and layer segmentation
algorithms, for 3D rendering and metrology of a layered spherical gradient refractive index
(S-GRIN) lens based on the imaging data collected by an angular scan optical coherence
tomography (OCT) system. The 3D mapping and rendering enables direct 3D visualization
and internal defect inspection of the lens. The metrology provides assessment of the surface
geometry, the lens thickness, the radii of curvature of the internal layer interfaces, and the
misalignment of the internal S-GRIN distribution with respect to the lens surface. The OCT
metrology results identify the manufacturing defects, and enable targeted process
development for optimizing the manufacturing parameters. The newly fabricated S-GRIN
lenses show up to a 7x spherical aberration reduction that allows a significantly increased
utilizable effective aperture.
© 2016 Optical Society of America
OCIS codes: (120.0120) Instrumentation, measurement, and metrology; (110.4500) Optical coherence tomography;
(120.4630) Optical inspection; (110.0110) Imaging systems.
Papa, J.; Rolland, J. P.; Howard, J.
Starting Points for Designing Freeform Four-Mirror Telescopes Conference
2016.
BibTeX | Tags: design, related
@conference{Papa2016a,
title = {Starting Points for Designing Freeform Four-Mirror Telescopes},
author = {Papa, J. and J.P. Rolland and J. Howard },
year = {2016},
date = {2016-00-00},
keywords = {design, related},
pubstate = {published},
tppubtype = {conference}
}
2015
Huang, J.; Yao, J.; Cirucci, N.; Ivanov, T.; Rolland, J. P.
Performance analysis of optical coherence tomography in the context of a thickness estimation task Journal Article
In: Journal of Biomedical Optics, vol. 20, no. 12, pp. 121306, 2015.
Abstract | Links | BibTeX | Tags: related, testing
@article{Huang15,
title = {Performance analysis of optical coherence tomography in the context of a thickness estimation task},
author = {Huang, J. and J. Yao and N. Cirucci and T. Ivanov and J. P. Rolland},
url = {https://www.spiedigitallibrary.org/journals/journal-of-biomedical-optics/volume-20/issue-12/121306/Performance-analysis-of-optical-coherence-tomography-in-the-context-of/10.1117/1.JBO.20.12.121306.full},
doi = {https://doi.org/10.1117/1.JBO.20.12.121306},
year = {2015},
date = {2015-12-01},
urldate = {2015-12-01},
journal = {Journal of Biomedical Optics},
volume = {20},
number = {12},
pages = {121306},
abstract = {Thickness estimation is a common task in optical coherence tomography (OCT). This study discusses and quantifies the intensity noise of three commonly used broadband sources, such as a supercontinuum source, a superluminescent diode (SLD), and a swept source. The performance of the three optical sources was evaluated for a thickness estimation task using both the fast Fourier transform (FFT) and maximum-likelihood (ML) estimators. We find that the source intensity noise has less impact on a thickness estimation task compared to the width of the axial point-spread function (PSF) and the trigger jittering noise of a swept source. Findings further show that the FFT estimator yields biased estimates, which can be as large as 10% of the thickness under test in the worst case. The ML estimator is by construction asymptotically unbiased and displays a 10× improvement in precision for both the supercontinuum and SLD sources. The ML estimator also shows the ability to estimate thickness that is at least 10× thinner compared to the FFT estimator. Finally, findings show that a supercontinuum source combined with the ML estimator enables unbiased nanometer-class thickness estimation with nanometer-scale precision.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {article}
}
Thickness estimation is a common task in optical coherence tomography (OCT). This study discusses and quantifies the intensity noise of three commonly used broadband sources, such as a supercontinuum source, a superluminescent diode (SLD), and a swept source. The performance of the three optical sources was evaluated for a thickness estimation task using both the fast Fourier transform (FFT) and maximum-likelihood (ML) estimators. We find that the source intensity noise has less impact on a thickness estimation task compared to the width of the axial point-spread function (PSF) and the trigger jittering noise of a swept source. Findings further show that the FFT estimator yields biased estimates, which can be as large as 10% of the thickness under test in the worst case. The ML estimator is by construction asymptotically unbiased and displays a 10× improvement in precision for both the supercontinuum and SLD sources. The ML estimator also shows the ability to estimate thickness that is at least 10× thinner compared to the FFT estimator. Finally, findings show that a supercontinuum source combined with the ML estimator enables unbiased nanometer-class thickness estimation with nanometer-scale precision.
Kitt, A.; Rolland, J. P.; Vamivakas, A. N.
Visible metasurfaces and ruled diffraction gratings: a comparison Journal Article
In: Opt. Express, vol. 5, no. 12, pp. 2895-2901, 2015.
Abstract | Links | BibTeX | Tags: design, related
@article{Kitt15,
title = {Visible metasurfaces and ruled diffraction gratings: a comparison},
author = {Kitt, A. and J. P. Rolland and A. N. Vamivakas},
doi = {https://doi.org/10.1364/OME.5.002895},
year = {2015},
date = {2015-11-23},
urldate = {2015-11-23},
journal = {Opt. Express},
volume = {5},
number = {12},
pages = {2895-2901},
abstract = {Metasurface based and physical ruling based diffraction gratings function by controlling the phase of light, but the origin of the phase control is different. Here we compare the simulated optical response of a 1800 lines/mm ruled diffraction grating blazed for 650 nm light to the response of a 1800 lines/mm phase grating meta-surface designed for efficiency in the visible. The efficiencies are comparable; the transverse electric polarized efficiency of the meta-surface based grating is similar to the transverse magnetic polarized efficiency of the ruled-grating. However, due to the different mechanisms of phase accrual, the meta-surface based grating does not exhibit grating anomalies and has low efficiency for transverse magnetic polarized light.},
keywords = {design, related},
pubstate = {published},
tppubtype = {article}
}
Metasurface based and physical ruling based diffraction gratings function by controlling the phase of light, but the origin of the phase control is different. Here we compare the simulated optical response of a 1800 lines/mm ruled diffraction grating blazed for 650 nm light to the response of a 1800 lines/mm phase grating meta-surface designed for efficiency in the visible. The efficiencies are comparable; the transverse electric polarized efficiency of the meta-surface based grating is similar to the transverse magnetic polarized efficiency of the ruled-grating. However, due to the different mechanisms of phase accrual, the meta-surface based grating does not exhibit grating anomalies and has low efficiency for transverse magnetic polarized light.
Giannechini, L.
Design and Quantification of Highly Corrosion-Resistant Magnetorheological Finishing Powder Masters Thesis
University of Rochester, Department of Mechanical Engineering, 2015.
Abstract | Links | BibTeX | Tags: manufacturing, related
@mastersthesis{Giannechini2015,
title = {Design and Quantification of Highly Corrosion-Resistant Magnetorheological Finishing Powder},
author = {Giannechini, L.},
url = {https://www.lle.rochester.edu/media/publications/documents/theses/Giannechini.pdf},
year = {2015},
date = {2015-11-10},
urldate = {2015-11-10},
address = {Department of Mechanical Engineering},
school = {University of Rochester},
abstract = {The purpose of this work is to increase the corrosion resistance of micron-sized zirconia
coated iron powders, and to develop a reliable and precise method of quantifying a
variety of the material's parameters. The powders that were tested are used as the base
of the magnetorheological nishing slurries in the Magnetorehological Finishing (MRF)
lab at the Laboratory for Laser Energetics. Development of the following methods
enables quantitative comparisons between various batches of MRF powder, and serves
as a metric for variations in performance. In this work, methods for the quanti cation of:
corrosion time, mass fraction of the elements in the bulk powder, powder density, particle
size distribution, concentration of free zirconia, and coating thickness were developed.
This research was performed as a result of recent MRF work combining the e ects of
acid etching and mechanical removal of material into a single process, which made it
necessary to both increase the corrosion resistance of the material, as well as to de ning
di erences between the two iterations of the product. Several techniques were used
to obtain the data necessary for analysis of the powders. A full factorial experiment
was employed to determine what factors to alter in the powder production. Techniques
including XRD, XPS, EDS, and XRF were all utilized in determining the relative mass
fraction of the components present in the powder. Gas pycnometry and colloidal analysis
were used to determine densities and particle size distributions. Magnetic separation
and centrifugation were used to isolate and condense the nonmagnetic free zirconia
present in the samples. Scanning electron microscopy (SEM) micrographs of particle
cross sections enabled analysis of coating thicknesses. Increasing the concentration of
zirconia during the coating procedure resulted in a positive correlation with improved
corrosion resistance. Of the methods used to analyze mass fraction, XRF proved to
be the fastest and most reliable. If further improvements in corrosion resistance are
required, it is recommended to increase the thickness of the zirconia coating, or develop
a dual coating of an acid resistant polymer and zirconia (although this may have adverse
e ects on the powder's magnetic potential).},
type = {related},
keywords = {manufacturing, related},
pubstate = {published},
tppubtype = {mastersthesis}
}
The purpose of this work is to increase the corrosion resistance of micron-sized zirconia
coated iron powders, and to develop a reliable and precise method of quantifying a
variety of the material's parameters. The powders that were tested are used as the base
of the magnetorheological nishing slurries in the Magnetorehological Finishing (MRF)
lab at the Laboratory for Laser Energetics. Development of the following methods
enables quantitative comparisons between various batches of MRF powder, and serves
as a metric for variations in performance. In this work, methods for the quanti cation of:
corrosion time, mass fraction of the elements in the bulk powder, powder density, particle
size distribution, concentration of free zirconia, and coating thickness were developed.
This research was performed as a result of recent MRF work combining the e ects of
acid etching and mechanical removal of material into a single process, which made it
necessary to both increase the corrosion resistance of the material, as well as to de ning
di erences between the two iterations of the product. Several techniques were used
to obtain the data necessary for analysis of the powders. A full factorial experiment
was employed to determine what factors to alter in the powder production. Techniques
including XRD, XPS, EDS, and XRF were all utilized in determining the relative mass
fraction of the components present in the powder. Gas pycnometry and colloidal analysis
were used to determine densities and particle size distributions. Magnetic separation
and centrifugation were used to isolate and condense the nonmagnetic free zirconia
present in the samples. Scanning electron microscopy (SEM) micrographs of particle
cross sections enabled analysis of coating thicknesses. Increasing the concentration of
zirconia during the coating procedure resulted in a positive correlation with improved
corrosion resistance. Of the methods used to analyze mass fraction, XRF proved to
be the fastest and most reliable. If further improvements in corrosion resistance are
required, it is recommended to increase the thickness of the zirconia coating, or develop
a dual coating of an acid resistant polymer and zirconia (although this may have adverse
e ects on the powder's magnetic potential).
coated iron powders, and to develop a reliable and precise method of quantifying a
variety of the material's parameters. The powders that were tested are used as the base
of the magnetorheological nishing slurries in the Magnetorehological Finishing (MRF)
lab at the Laboratory for Laser Energetics. Development of the following methods
enables quantitative comparisons between various batches of MRF powder, and serves
as a metric for variations in performance. In this work, methods for the quanti cation of:
corrosion time, mass fraction of the elements in the bulk powder, powder density, particle
size distribution, concentration of free zirconia, and coating thickness were developed.
This research was performed as a result of recent MRF work combining the e ects of
acid etching and mechanical removal of material into a single process, which made it
necessary to both increase the corrosion resistance of the material, as well as to de ning
di erences between the two iterations of the product. Several techniques were used
to obtain the data necessary for analysis of the powders. A full factorial experiment
was employed to determine what factors to alter in the powder production. Techniques
including XRD, XPS, EDS, and XRF were all utilized in determining the relative mass
fraction of the components present in the powder. Gas pycnometry and colloidal analysis
were used to determine densities and particle size distributions. Magnetic separation
and centrifugation were used to isolate and condense the nonmagnetic free zirconia
present in the samples. Scanning electron microscopy (SEM) micrographs of particle
cross sections enabled analysis of coating thicknesses. Increasing the concentration of
zirconia during the coating procedure resulted in a positive correlation with improved
corrosion resistance. Of the methods used to analyze mass fraction, XRF proved to
be the fastest and most reliable. If further improvements in corrosion resistance are
required, it is recommended to increase the thickness of the zirconia coating, or develop
a dual coating of an acid resistant polymer and zirconia (although this may have adverse
e ects on the powder's magnetic potential).
Yao, J.; Huang, J.; Meemon, P.; Ponting, M.; Rolland, J. P.
In: Opt. Express, vol. 23, no. 23, pp. 30149-30164, 2015.
Abstract | Links | BibTeX | Tags: related, testing
@article{YAO15b,
title = {Simultaneous estimation of thickness and refractive index of layered gradient refractive index optics using a hybrid confocal-scan swept-source optical coherence tomography system},
author = {Yao, J. and J. Huang and P. Meemon and M. Ponting and J. P. Rolland},
doi = {https://doi.org/10.1364/OE.23.030149},
year = {2015},
date = {2015-11-10},
urldate = {2015-11-10},
journal = {Opt. Express},
volume = {23},
number = {23},
pages = {30149-30164},
abstract = {A hybrid confocal-scan swept-source optical coherence tomography metrology system was conceived for simultaneous measurements of the refractive index and thickness profiles of polymeric layered gradient refractive index (GRIN) optics. An uncertainty analysis predicts the metrology capability of the system and guides the selection of an optimum working numerical aperture. Experimental results on both a monolithic and a GRIN layered sheet are demonstrated to be in close agreement with theoretical predictions. Index measurement precision reached 0.0001 and 0.0008 for measuring 2.8 mm and ~300 µm thick layers, respectively. The thicknesses of these layers were simultaneously measured with a precision of 0.28 and 0.17 µm, respectively.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {article}
}
A hybrid confocal-scan swept-source optical coherence tomography metrology system was conceived for simultaneous measurements of the refractive index and thickness profiles of polymeric layered gradient refractive index (GRIN) optics. An uncertainty analysis predicts the metrology capability of the system and guides the selection of an optimum working numerical aperture. Experimental results on both a monolithic and a GRIN layered sheet are demonstrated to be in close agreement with theoretical predictions. Index measurement precision reached 0.0001 and 0.0008 for measuring 2.8 mm and ~300 µm thick layers, respectively. The thicknesses of these layers were simultaneously measured with a precision of 0.28 and 0.17 µm, respectively.
Gray, R.
2015.
Abstract | Links | BibTeX | Tags: design, related
@phdthesis{GRAY-THESIS,
title = {Investigation of the Field Dependence of the Aberration Functions of Rotationally Nonsymmetric Optical Imaging Systems},
author = {Gray, R.},
url = {https://urresearch.rochester.edu/institutionalPublicationPublicView.action?institutionalItemId=29981&versionNumber=1},
year = {2015},
date = {2015-11-06},
urldate = {2015-11-06},
abstract = {It is shown how Shack’s vector product (SVP) can be used to express the expansion of the monochromatic wavefront aberration function for rotationally symmetric optical imaging models using the H. H. Hopkins’ expansion coefficients. As a result of this research it was discovered that SVP fits naturally within the framework of 2-dimensional Geometric Algebra (GA). It is further shown how SVP can be used to define two-dimensional vectors in terms of the Zernike polynomials. The wavefront aberration function expansion is then expressed in terms of these Zernike vectors. A method for calculating the H. H. Hopkins’ expansion coefficients is described, including the calculation of the per surface, sphere/asphere, intrinsic/extrinsic expansion coefficient contributions. Methods for converting the Zernike expansion coefficients into the H. H. Hopkins’ expansion coefficients have been developed and are presented in this work. Nodal aberration theory (NAT), now well established in the literature, is presented in terms of these mathematical developments. As a quantitative validation of the NAT predications of an optical system’s field dependence, comparisons are made between the full field displays (FFDs) produced by using a double Zernike expansion of the wavefront aberration function and by application of NAT to rotationally symmetric optical imaging systems having one or more surfaces decentered and/or tilted. Validation of these developments is provided using idealized computer models of several space telescopes having one or more optical surfaces decentered and/or tilted. Initial steps toward one approach for extending NAT to include optical imaging systems containing freeform surface shapes defined by Zernike polynomials is also provided.},
keywords = {design, related},
pubstate = {published},
tppubtype = {phdthesis}
}
It is shown how Shack’s vector product (SVP) can be used to express the expansion of the monochromatic wavefront aberration function for rotationally symmetric optical imaging models using the H. H. Hopkins’ expansion coefficients. As a result of this research it was discovered that SVP fits naturally within the framework of 2-dimensional Geometric Algebra (GA). It is further shown how SVP can be used to define two-dimensional vectors in terms of the Zernike polynomials. The wavefront aberration function expansion is then expressed in terms of these Zernike vectors. A method for calculating the H. H. Hopkins’ expansion coefficients is described, including the calculation of the per surface, sphere/asphere, intrinsic/extrinsic expansion coefficient contributions. Methods for converting the Zernike expansion coefficients into the H. H. Hopkins’ expansion coefficients have been developed and are presented in this work. Nodal aberration theory (NAT), now well established in the literature, is presented in terms of these mathematical developments. As a quantitative validation of the NAT predications of an optical system’s field dependence, comparisons are made between the full field displays (FFDs) produced by using a double Zernike expansion of the wavefront aberration function and by application of NAT to rotationally symmetric optical imaging systems having one or more surfaces decentered and/or tilted. Validation of these developments is provided using idealized computer models of several space telescopes having one or more optical surfaces decentered and/or tilted. Initial steps toward one approach for extending NAT to include optical imaging systems containing freeform surface shapes defined by Zernike polynomials is also provided.
Salzman, S.; Romanofsky, H. J.; Giannechini, L. J.; Jacobs, S. D.; Lambropoulos, J. C.
Magnetorheological finishing of chemical-vapor-deposited zinc sulfide via chemically and mechanically modified fluids Journal Article
In: Applied Optics, vol. 55, no. 6, pp. 1481, 2015.
Abstract | Links | BibTeX | Tags: manufacturing, related
@article{Salzman15,
title = {Magnetorheological finishing of chemical-vapor-deposited zinc sulfide via chemically and mechanically modified fluids},
author = {Salzman, S. and H. J. Romanofsky and L. J. Giannechini and S. D. Jacobs and J. C. Lambropoulos},
doi = {https://doi.org/10.1364/AO.55.001481},
year = {2015},
date = {2015-11-03},
urldate = {2015-11-03},
journal = {Applied Optics},
volume = {55},
number = {6},
pages = {1481},
abstract = {We describe the anisotropy in the material-removal rate (MRR) of the polycrystalline, chemical-vapor–deposited (CVD) zinc sulfide (ZnS). We define the polycrystalline anisotropy via microhardness and chemical erosion tests for four crystallographic orientations of ZnS: (100), (110), (111), and (311). Anisotropy in the MRR was studied under magnetorheological finishing (MRF) conditions. Three chemically and mechanically modified magnetorheological (MR) fluids at pH values of 4, 5, and 6 were used to test the MRR variations among the four single-crystal planes. When polishing the single-crystal planes and the polycrystalline with pH 5 and pH 6 MR fluids, variations were found in the MRR among the four single-crystal planes and surface artifacts were observed on the polycrystalline material. When polishing the single-crystal planes and the polycrystalline with the modified MR fluid at pH 4, however, minimal variation was observed in the MRR among the four orientations and a reduction in surface artifacts was achieved on the polycrystalline material.},
keywords = {manufacturing, related},
pubstate = {published},
tppubtype = {article}
}
We describe the anisotropy in the material-removal rate (MRR) of the polycrystalline, chemical-vapor–deposited (CVD) zinc sulfide (ZnS). We define the polycrystalline anisotropy via microhardness and chemical erosion tests for four crystallographic orientations of ZnS: (100), (110), (111), and (311). Anisotropy in the MRR was studied under magnetorheological finishing (MRF) conditions. Three chemically and mechanically modified magnetorheological (MR) fluids at pH values of 4, 5, and 6 were used to test the MRR variations among the four single-crystal planes. When polishing the single-crystal planes and the polycrystalline with pH 5 and pH 6 MR fluids, variations were found in the MRR among the four single-crystal planes and surface artifacts were observed on the polycrystalline material. When polishing the single-crystal planes and the polycrystalline with the modified MR fluid at pH 4, however, minimal variation was observed in the MRR among the four orientations and a reduction in surface artifacts was achieved on the polycrystalline material.
Moore, D. B.; Fienup, J. R.
Sub-Aperture Position Estimation in Transverse-Translation Diversity Wavefront Sensing Conference
2015.
Abstract | Links | BibTeX | Tags: related, testing
@conference{Moore_AOMS_2015,
title = {Sub-Aperture Position Estimation in Transverse-Translation Diversity Wavefront Sensing},
author = {D. B. Moore and J.R. Fienup},
doi = {10.1364/AOMS.2015.AOM3F.4},
year = {2015},
date = {2015-10-21},
journal = {Imaging and Applied Optics 2015 OSA Technical Digest (online) (Optical Society of America, 2015)},
pages = {AOM3F.4},
abstract = {Image-based wavefront sensing involving a sub-aperture translating in an unknown fashion in a pupil plane is demonstrated experimentally in the case that the target is also translating in an unknown fashion.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {conference}
}
Image-based wavefront sensing involving a sub-aperture translating in an unknown fashion in a pupil plane is demonstrated experimentally in the case that the target is also translating in an unknown fashion.
Yao, Jianing; Xu, Di; Zhao, Nan; Rolland, Jannick P.
Proceedings of SPIE, vol. 9633, no. 96331A, 2015.
Abstract | Links | BibTeX | Tags: related, testing
@conference{Yao15optifab,
title = {Freeform metrology using swept-source optical coherence tomography with custom pupil-relay precision scanning configuration},
author = {Jianing Yao and Di Xu and Nan Zhao and Jannick P. Rolland},
doi = {https://doi.org/10.1117/12.2195939},
year = {2015},
date = {2015-10-11},
urldate = {2015-10-11},
booktitle = {Proceedings of SPIE},
volume = {9633},
number = {96331A},
abstract = {The recent advances in the optics manufacturing industry to achieve the capability of fabricating rotationally nonsymmetric optical quality surfaces have considerably stimulated the optical designs with freeform components. This opens up new horizons for novel optical systems with larger fields of view and higher performance, or significantly more compact in volume at equal performance compared to conventional systems. A bottleneck to the broad industrial applications of freeform optics remains the lack of a high performance optical metrology tool capable of measuring significant surface departures and slopes of the parts. To address this issue, we have developed a fiber-based swept-source optical coherence tomography (SS-OCT) system for point-cloud freeform metrology, where two-axis galvanometer scanners are leveraged for high-speed lateral scans. We specifically designed a custom all-reflective achromatic pupil relay system to achieve a diffraction-limited scanning configuration. Coupled with a large field-of-view (FOV) telecentric scan lens, the imaging covers 28.9 mm × 28.9 mm FOV with 35 μm lateral resolution and more than 600 μm depth of focus. Freeform metrology is demonstrated for an Alvarez surface of 400 μm surface sag. The high sensitivity of the SS-OCT system allows for capturing the slope variations of the part up to the maximum slope that is 5 degrees in this case. Specific surface reconstruction, rendering and fitting algorithms were developed to evaluate the metrology results and investigate the accuracy and precision of the measurements.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {conference}
}
The recent advances in the optics manufacturing industry to achieve the capability of fabricating rotationally nonsymmetric optical quality surfaces have considerably stimulated the optical designs with freeform components. This opens up new horizons for novel optical systems with larger fields of view and higher performance, or significantly more compact in volume at equal performance compared to conventional systems. A bottleneck to the broad industrial applications of freeform optics remains the lack of a high performance optical metrology tool capable of measuring significant surface departures and slopes of the parts. To address this issue, we have developed a fiber-based swept-source optical coherence tomography (SS-OCT) system for point-cloud freeform metrology, where two-axis galvanometer scanners are leveraged for high-speed lateral scans. We specifically designed a custom all-reflective achromatic pupil relay system to achieve a diffraction-limited scanning configuration. Coupled with a large field-of-view (FOV) telecentric scan lens, the imaging covers 28.9 mm × 28.9 mm FOV with 35 μm lateral resolution and more than 600 μm depth of focus. Freeform metrology is demonstrated for an Alvarez surface of 400 μm surface sag. The high sensitivity of the SS-OCT system allows for capturing the slope variations of the part up to the maximum slope that is 5 degrees in this case. Specific surface reconstruction, rendering and fitting algorithms were developed to evaluate the metrology results and investigate the accuracy and precision of the measurements.
Huang, J.; Yao, J.; Cirucci, N. M.; Ivanov, T.; Rolland, J. P.
Thickness estimation with optical coherence tomography and statistical decision theory Conference
proceeding of SPIE, vol. 9633, no. 96330P, 2015.
Abstract | Links | BibTeX | Tags: related, testing
@conference{Huangoptifab15,
title = {Thickness estimation with optical coherence tomography and statistical decision theory},
author = {Huang, J. and J. Yao and N.M. Cirucci and T. Ivanov and J.P. Rolland},
doi = {https://doi.org/10.1117/12.2195969},
year = {2015},
date = {2015-10-11},
urldate = {2015-10-11},
booktitle = {proceeding of SPIE},
volume = {9633},
number = {96330P},
abstract = {Thickness estimation, which has a broad range of applications, plays an important role in the field of optical metrology. In this study, we investigate a new approach—combining optical coherence tomography (OCT) and statistical decision theory—for thickness estimation. We first discussed and quantified the intensity noise of three commonly used broadband sources, a super-continuum source, a super-luminescent diode (SLD), and a swept source. Furthermore, a maximum-likelihood (ML) estimator was implemented to interpret the OCT raw data. Based on the mathematical model and the ML estimator, simulations were set up to investigate the impact of different broadband sources in OCT for a thickness estimation task. We then validated the theoretical framework with physical phantoms. Results demonstrate unbiased nanometer-class thickness estimates with the ML estimator. The framework can be potentially used for film and surface shape metrology.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {conference}
}
Thickness estimation, which has a broad range of applications, plays an important role in the field of optical metrology. In this study, we investigate a new approach—combining optical coherence tomography (OCT) and statistical decision theory—for thickness estimation. We first discussed and quantified the intensity noise of three commonly used broadband sources, a super-continuum source, a super-luminescent diode (SLD), and a swept source. Furthermore, a maximum-likelihood (ML) estimator was implemented to interpret the OCT raw data. Based on the mathematical model and the ML estimator, simulations were set up to investigate the impact of different broadband sources in OCT for a thickness estimation task. We then validated the theoretical framework with physical phantoms. Results demonstrate unbiased nanometer-class thickness estimates with the ML estimator. The framework can be potentially used for film and surface shape metrology.
Canavesi, C.; Cogliati, A.; Hayes, A.; Santhanam, A. P.; Tankam, P.; Rolland, J. P.
Proceedings of the SPIE, vol. 9633, no. 96330O, 2015.
Abstract | Links | BibTeX | Tags: related, testing
@conference{Canavesioptifab15,
title = {Gabor-domain optical coherence microscopy with integrated dual-axis MEMS scanner for fast 3D imaging and metrology},
author = {Canavesi, C. and A. Cogliati and A. Hayes and A.P. Santhanam and P. Tankam and J.P. Rolland},
doi = {https://doi.org/10.1117/12.2195828},
year = {2015},
date = {2015-10-11},
urldate = {2015-10-11},
booktitle = {Proceedings of the SPIE},
volume = {9633},
number = {96330O},
abstract = {Fast, robust, nondestructive 3D imaging is needed for characterization of microscopic structures in industrial and clinical applications. A custom micro-electromechanical system (MEMS)-based 2D scanner system was developed to achieve 55 kHz A-scan acquisition in a Gabor-domain optical coherence microscopy (GD-OCM) instrument with a novel multilevel GPU architecture for high-speed imaging. GD-OCM yields high-definition volumetric imaging with dynamic depth of focusing through a bio-inspired liquid lens-based microscope design, which has no moving parts and is suitable for use in a manufacturing setting or in a medical environment. A dual-axis MEMS mirror was chosen to replace two single-axis galvanometer mirrors; as a result, the astigmatism caused by the mismatch between the optical pupil and the scanning location was eliminated and a 12x reduction in volume of the scanning system was achieved. Imaging at an invariant resolution of 2 μm was demonstrated throughout a volume of 1 × 1 × 0.6 mm3, acquired in less than 2 minutes. The MEMS-based scanner resulted in improved image quality, increased robustness and lighter weight of the system – all factors that are critical for on-field deployment. A custom integrated feedback system consisting of a laser diode and a position-sensing detector was developed to investigate the impact of the resonant frequency of the MEMS and the driving signal of the scanner on the movement of the mirror. Results on the metrology of manufactured materials and characterization of tissue samples with GD-OCM are presented.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {conference}
}
Fast, robust, nondestructive 3D imaging is needed for characterization of microscopic structures in industrial and clinical applications. A custom micro-electromechanical system (MEMS)-based 2D scanner system was developed to achieve 55 kHz A-scan acquisition in a Gabor-domain optical coherence microscopy (GD-OCM) instrument with a novel multilevel GPU architecture for high-speed imaging. GD-OCM yields high-definition volumetric imaging with dynamic depth of focusing through a bio-inspired liquid lens-based microscope design, which has no moving parts and is suitable for use in a manufacturing setting or in a medical environment. A dual-axis MEMS mirror was chosen to replace two single-axis galvanometer mirrors; as a result, the astigmatism caused by the mismatch between the optical pupil and the scanning location was eliminated and a 12x reduction in volume of the scanning system was achieved. Imaging at an invariant resolution of 2 μm was demonstrated throughout a volume of 1 × 1 × 0.6 mm3, acquired in less than 2 minutes. The MEMS-based scanner resulted in improved image quality, increased robustness and lighter weight of the system – all factors that are critical for on-field deployment. A custom integrated feedback system consisting of a laser diode and a position-sensing detector was developed to investigate the impact of the resonant frequency of the MEMS and the driving signal of the scanner on the movement of the mirror. Results on the metrology of manufactured materials and characterization of tissue samples with GD-OCM are presented.
Gray, R.; Rolland, J. P.
Wavefront aberration function in terms of R.V. Shack’s vector product and Zernike polynomial vectors Journal Article
In: JOSA A, vol. 32, no. 10, pp. 1836-1847, 2015.
Abstract | Links | BibTeX | Tags: design, related
@article{GRAY15,
title = {Wavefront aberration function in terms of R.V. Shack’s vector product and Zernike polynomial vectors},
author = {Gray, R. and J. P. Rolland},
doi = {https://doi.org/10.1364/JOSAA.32.001836},
year = {2015},
date = {2015-08-18},
urldate = {2015-08-18},
journal = {JOSA A},
volume = {32},
number = {10},
pages = {1836-1847},
abstract = {Previous papers have shown how, for rotationally symmetric optical imaging systems, nodes in the field dependence of the wavefront aberration function develop when a rotationally symmetric optical surface within an imaging optical system is decentered and/or tilted. In this paper, we show how Shack’s vector product (SVP) can be used to express the wavefront aberration function and to define vectors in terms of the Zernike polynomials. The wavefront aberration function is then expressed in terms of the Zernike vectors. It is further shown that SVP fits within the framework of two-dimensional geometric algebra (GA). Within the GA framework, an equation for the third-order node locations for the binodal astigmatism term that emerge in the presence of tilts and decenters is then demonstrated. A computer model of a three-mirror telescope system is used to demonstrate the validity of the mathematical development.},
keywords = {design, related},
pubstate = {published},
tppubtype = {article}
}
Previous papers have shown how, for rotationally symmetric optical imaging systems, nodes in the field dependence of the wavefront aberration function develop when a rotationally symmetric optical surface within an imaging optical system is decentered and/or tilted. In this paper, we show how Shack’s vector product (SVP) can be used to express the wavefront aberration function and to define vectors in terms of the Zernike polynomials. The wavefront aberration function is then expressed in terms of the Zernike vectors. It is further shown that SVP fits within the framework of two-dimensional geometric algebra (GA). Within the GA framework, an equation for the third-order node locations for the binodal astigmatism term that emerge in the presence of tilts and decenters is then demonstrated. A computer model of a three-mirror telescope system is used to demonstrate the validity of the mathematical development.
Duma, V.; Tankam, P.; Huang, J.; Won, J.; J. P. Rolland,
Optimization of galvanometer scanning for optical coherence tomography Journal Article
In: Applied Optics, vol. 54, no. 17, pp. 5495-5507, 2015.
Abstract | Links | BibTeX | Tags: related, testing
@article{DUMA15,
title = {Optimization of galvanometer scanning for optical coherence tomography},
author = {Duma, V. and P. Tankam and J. Huang and J. Won and J. P. Rolland,},
doi = {https://doi.org/10.1364/AO.54.005495},
year = {2015},
date = {2015-06-10},
urldate = {2015-06-10},
journal = {Applied Optics},
volume = {54},
number = {17},
pages = {5495-5507},
abstract = {We study experimentally the effective duty cycle of galvanometer-based scanners (GSs) with regard to three main parameters of the scanning process: theoretical/imposed duty cycle (of the input signal), scan frequency, and scan amplitude. Sawtooth and triangular input signals for the device are considered. The effects of the mechanical inertia of the oscillatory element of the GS are analyzed and their consequences are discussed in the context of optical coherence tomography (OCT) imaging. When the theoretical duty cycle and the scan amplitude are increased to the limit, the saturation of the device is demonstrated for a useful range of scan frequencies by direct measurement of the position of the galvomirror. Investigations of OCT imaging of large samples also validate this saturation, as examplified by the gaps/blurred portions obtained between neighboring images when using both triangular and sawtooth scanning at high scan frequencies. For this latter aspect, the necessary overlap between neighboring B-scans, and therefore between the corresponding volumetric reconstructions of the sample, are evaluated and implemented with regard to the same parameters of the scanning process. OCT images that are free of these artifacts are thus obtained.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {article}
}
We study experimentally the effective duty cycle of galvanometer-based scanners (GSs) with regard to three main parameters of the scanning process: theoretical/imposed duty cycle (of the input signal), scan frequency, and scan amplitude. Sawtooth and triangular input signals for the device are considered. The effects of the mechanical inertia of the oscillatory element of the GS are analyzed and their consequences are discussed in the context of optical coherence tomography (OCT) imaging. When the theoretical duty cycle and the scan amplitude are increased to the limit, the saturation of the device is demonstrated for a useful range of scan frequencies by direct measurement of the position of the galvomirror. Investigations of OCT imaging of large samples also validate this saturation, as examplified by the gaps/blurred portions obtained between neighboring images when using both triangular and sawtooth scanning at high scan frequencies. For this latter aspect, the necessary overlap between neighboring B-scans, and therefore between the corresponding volumetric reconstructions of the sample, are evaluated and implemented with regard to the same parameters of the scanning process. OCT images that are free of these artifacts are thus obtained.
Yao, J.; Meemon, P.; Ponting, M.; Rolland, J. P.
Metrology of 3D freeform spherical gradient index preforms Conference
Imaging and Applied Optics 2015OSA Technical Digest, no. FT3B.3 , 2015, (Imaging and Applied Optics 2015, OSA Technical Digest, paper FT3B.3 (2015). ).
Abstract | Links | BibTeX | Tags: related, testing
@conference{Yao15pa,
title = {Metrology of 3D freeform spherical gradient index preforms},
author = {Yao, J. and P. Meemon and M. Ponting and J. P. Rolland},
doi = {https://doi.org/10.1364/FREEFORM.2015.FT3B.3},
year = {2015},
date = {2015-06-08},
urldate = {2015-06-08},
booktitle = {Imaging and Applied Optics 2015OSA Technical Digest},
number = {FT3B.3 },
abstract = {We present an angular-scan swept-source optical coherence tomography system for 3D imaging and concentricity characterization of two generations of spherical gradient index preforms with a method to decouple the physical thickness and the index measurements.},
note = {Imaging and Applied Optics 2015, OSA Technical Digest, paper FT3B.3 (2015). },
keywords = {related, testing},
pubstate = {published},
tppubtype = {conference}
}
We present an angular-scan swept-source optical coherence tomography system for 3D imaging and concentricity characterization of two generations of spherical gradient index preforms with a method to decouple the physical thickness and the index measurements.
Evans, C. J.; Browy, E. C.; Childs, T. H. C.; Paul, E.
Interferometric measurements of single crystal diamond tool wear Journal Article
In: CIRP Annals - Manufacturing Technology, vol. 64, pp. 125-128, 2015.
Abstract | Links | BibTeX | Tags: related, testing
@article{Evans15,
title = {Interferometric measurements of single crystal diamond tool wear},
author = {Evans, C. J. and E.C. Browy and T.H.C. Childs and E. Paul },
doi = {https://doi.org/10.1016/j.cirp.2015.04.066},
year = {2015},
date = {2015-05-04},
urldate = {2015-05-04},
journal = {CIRP Annals - Manufacturing Technology},
volume = {64},
pages = {125-128},
abstract = {Interferometric measurements of plunge cuts made in a reference component intermittently during cutting tool wear tests allow measurement of the detail of tool edge recession without removing the tool from the machine. Hence the evolution of the tool wear can be evaluated with a resolution of less than 5 nm. A plunge cut using the new tool is subtracted from subsequent measurements, providing a direct measure of wear and removing bias from the scanning white light interferometer that would arise from non-zero slopes in the field of view. The method is illustrated with results from single crystal diamond tool wear tests when machining a family of nickel-copper alloys of varying composition. The dominant wear mechanism depends on the alloy and the cutting parameters. Nose flattening, leading edge recession, chipping, and formation of Pekelharing grooves can all be identified.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {article}
}
Interferometric measurements of plunge cuts made in a reference component intermittently during cutting tool wear tests allow measurement of the detail of tool edge recession without removing the tool from the machine. Hence the evolution of the tool wear can be evaluated with a resolution of less than 5 nm. A plunge cut using the new tool is subtracted from subsequent measurements, providing a direct measure of wear and removing bias from the scanning white light interferometer that would arise from non-zero slopes in the field of view. The method is illustrated with results from single crystal diamond tool wear tests when machining a family of nickel-copper alloys of varying composition. The dominant wear mechanism depends on the alloy and the cutting parameters. Nose flattening, leading edge recession, chipping, and formation of Pekelharing grooves can all be identified.
Huang, J.; Tankam, P.; Hindman, H. B.; Aquavella, J. V.; Clarkson, E.; Kupinski, M. A.; Rolland, J. P.
Tear film thickness estimation using optical coherence tomography and maximum-likelihood estimation Presentation
02.05.2015.
Abstract | Links | BibTeX | Tags: related, testing
@misc{Huangarvo,
title = {Tear film thickness estimation using optical coherence tomography and maximum-likelihood estimation},
author = {Huang, J. and P. Tankam and H. B. Hindman and J. V. Aquavella and E. Clarkson and M. A. Kupinski and J. P. Rolland},
doi = {10.1117/12.2083160},
year = {2015},
date = {2015-05-02},
urldate = {2015-05-02},
abstract = {In biophotonics imaging, one important and quantitative task is layer-thickness estimation. In this study, we investigate the approach of combining optical coherence tomography and a maximum-likelihood (ML) estimator for layer thickness estimation in the context of tear film imaging. The motivation of this study is to extend our understanding of tear film dynamics, which is the prerequisite to advance the management of Dry Eye Disease, through the simultaneous estimation of the thickness of the tear film lipid and aqueous layers. The estimator takes into account the different statistical processes associated with the imaging chain. We theoretically investigated the impact of key system parameters, such as the axial point spread functions (PSF) and various sources of noise on measurement uncertainty. Simulations show that an OCT system with a 1 μm axial PSF (FWHM) allows unbiased estimates down to nanometers with nanometer precision. In implementation, we built a customized Fourier domain OCT system that operates in the 600 to 1000 nm spectral window and achieves 0.93 micron axial PSF in corneal epithelium. We then validated the theoretical framework with physical phantoms made of custom optical coatings, with layer thicknesses from tens of nanometers to microns. Results demonstrate unbiased nanometer-class thickness estimates in three different physical phantoms.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {presentation}
}
In biophotonics imaging, one important and quantitative task is layer-thickness estimation. In this study, we investigate the approach of combining optical coherence tomography and a maximum-likelihood (ML) estimator for layer thickness estimation in the context of tear film imaging. The motivation of this study is to extend our understanding of tear film dynamics, which is the prerequisite to advance the management of Dry Eye Disease, through the simultaneous estimation of the thickness of the tear film lipid and aqueous layers. The estimator takes into account the different statistical processes associated with the imaging chain. We theoretically investigated the impact of key system parameters, such as the axial point spread functions (PSF) and various sources of noise on measurement uncertainty. Simulations show that an OCT system with a 1 μm axial PSF (FWHM) allows unbiased estimates down to nanometers with nanometer precision. In implementation, we built a customized Fourier domain OCT system that operates in the 600 to 1000 nm spectral window and achieves 0.93 micron axial PSF in corneal epithelium. We then validated the theoretical framework with physical phantoms made of custom optical coatings, with layer thicknesses from tens of nanometers to microns. Results demonstrate unbiased nanometer-class thickness estimates in three different physical phantoms.
Leach, R.; Evans, C.; He, L.; Davies, A.; Duparre, A.; Henning, A.; Jones, C.; O'Connor, D.
Open Questions in Surface Topography Measurement: a roadmap Journal Article
In: Surface Topography: Metrology and Properties, vol. 3, no. 1, pp. 013001, 2015.
Abstract | Links | BibTeX | Tags: related, testing
@article{Leach15,
title = {Open Questions in Surface Topography Measurement: a roadmap},
author = {Leach, R. and C. Evans and L. He and A. Davies and A. Duparre and A. Henning and C. Jones and D. O'Connor},
doi = {10.1088/2051-672X/3/1/013001},
year = {2015},
date = {2015-03-31},
urldate = {2015-03-31},
journal = {Surface Topography: Metrology and Properties},
volume = {3},
number = {1},
pages = {013001},
abstract = {Control of surface topography has always been of vital importance for manufacturing and many other engineering and scientific disciplines. However, despite over one hundred years of quantitative surface topography measurement, there are still many open questions. At the top of the list of questions is 'Are we getting the right answer?' This begs the obvious question 'How would we know?' There are many other questions relating to applications, the appropriateness of a technique for a given scenario, or the relationship between a particular analysis and the function of the surface. In this first 'open questions' article we have gathered together some experts in surface topography measurement and asked them to address timely, unresolved questions about the subject. We hope that their responses will go some way to answer these questions, address areas where further research is required, and look at the future of the subject. The first section 'Spatial content characterization for precision surfaces' addresses the need to characterise the spatial content of precision surfaces. Whilst we have been manufacturing optics for centuries, there still isn't a consensus on how to specify the surface for manufacture. The most common three methods for spatial characterisation are reviewed and compared, and the need for further work on quantifying measurement uncertainties is highlighted. The article is focussed on optical surfaces, but the ideas are more pervasive. Different communities refer to 'figure, mid-spatial frequencies, and finish' and 'form, waviness, and roughness', but the mathematics are identical. The second section 'Light scattering methods' is focussed on light scattering techniques; an important topic with in-line metrology becoming essential in many manufacturing scenarios. The potential of scattering methods has long been recognized; in the 'smooth surface limit' functionally significant relationships can be derived from first principles for statistically stationary, random surfaces. For rougher surfaces, correlations can be found experimentally for specific manufacturing processes. Improvements in computational methods encourage us to revisit light scattering as a powerful and versatile tool to investigate surface and thin film topographies, potentially providing information on both topography and defects over large areas at high speed. Future scattering techniques will be applied for complex film systems and for sub-surface damage measurement, but more research is required to quantify and standardise such measurements. A fundamental limitation of all topography measurement systems is their finite spatial bandwidth, which limits the slopes that they can detect. The third section 'Optical measurements of surfaces containing high slope angles' discusses this limitation and potential methods to overcome it. In some cases, a rough surface can allow measurement of slopes outside the classical optics limit, but more research is needed to fully understand this process. The last section 'What are the challenges for high dynamic range surface measurement?' presents the challenge facing metrologists by the use of surfaces that need measurement systems with very high spatial and temporal bandwidths, for example, those found in roll-to-roll manufacturing. High resolution, large areas and fast measurement times are needed, and these needs are unlikely to be fulfilled by developing a single all-purpose instrument. A toolbox of techniques needs to be developed which can be applied for any specific manufacturing scenario. The functional significance of surface topography has been known for centuries. Mirrors are smooth. Sliding behaviour depends on roughness. We have been measuring surfaces for centuries, but we still face many challenges. New manufacturing paradigms suggest that we need to make rapid measurements online that relate to the functional performance of the surface. This first 'open questions' collection addresses a subset of the challenges facing the surface metrology community. There are many more challenges which we would like to address in future 'open questions' articles. We welcome your feedback and your suggestions.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {article}
}
Control of surface topography has always been of vital importance for manufacturing and many other engineering and scientific disciplines. However, despite over one hundred years of quantitative surface topography measurement, there are still many open questions. At the top of the list of questions is 'Are we getting the right answer?' This begs the obvious question 'How would we know?' There are many other questions relating to applications, the appropriateness of a technique for a given scenario, or the relationship between a particular analysis and the function of the surface. In this first 'open questions' article we have gathered together some experts in surface topography measurement and asked them to address timely, unresolved questions about the subject. We hope that their responses will go some way to answer these questions, address areas where further research is required, and look at the future of the subject. The first section 'Spatial content characterization for precision surfaces' addresses the need to characterise the spatial content of precision surfaces. Whilst we have been manufacturing optics for centuries, there still isn't a consensus on how to specify the surface for manufacture. The most common three methods for spatial characterisation are reviewed and compared, and the need for further work on quantifying measurement uncertainties is highlighted. The article is focussed on optical surfaces, but the ideas are more pervasive. Different communities refer to 'figure, mid-spatial frequencies, and finish' and 'form, waviness, and roughness', but the mathematics are identical. The second section 'Light scattering methods' is focussed on light scattering techniques; an important topic with in-line metrology becoming essential in many manufacturing scenarios. The potential of scattering methods has long been recognized; in the 'smooth surface limit' functionally significant relationships can be derived from first principles for statistically stationary, random surfaces. For rougher surfaces, correlations can be found experimentally for specific manufacturing processes. Improvements in computational methods encourage us to revisit light scattering as a powerful and versatile tool to investigate surface and thin film topographies, potentially providing information on both topography and defects over large areas at high speed. Future scattering techniques will be applied for complex film systems and for sub-surface damage measurement, but more research is required to quantify and standardise such measurements. A fundamental limitation of all topography measurement systems is their finite spatial bandwidth, which limits the slopes that they can detect. The third section 'Optical measurements of surfaces containing high slope angles' discusses this limitation and potential methods to overcome it. In some cases, a rough surface can allow measurement of slopes outside the classical optics limit, but more research is needed to fully understand this process. The last section 'What are the challenges for high dynamic range surface measurement?' presents the challenge facing metrologists by the use of surfaces that need measurement systems with very high spatial and temporal bandwidths, for example, those found in roll-to-roll manufacturing. High resolution, large areas and fast measurement times are needed, and these needs are unlikely to be fulfilled by developing a single all-purpose instrument. A toolbox of techniques needs to be developed which can be applied for any specific manufacturing scenario. The functional significance of surface topography has been known for centuries. Mirrors are smooth. Sliding behaviour depends on roughness. We have been measuring surfaces for centuries, but we still face many challenges. New manufacturing paradigms suggest that we need to make rapid measurements online that relate to the functional performance of the surface. This first 'open questions' collection addresses a subset of the challenges facing the surface metrology community. There are many more challenges which we would like to address in future 'open questions' articles. We welcome your feedback and your suggestions.
Yao, J.; Meemon, P.; Ponting, M.; Rolland, J. P.
Angular scan optical coherence tomography imaging and metrology of spherical gradient refractive index preforms Journal Article
In: Opt. Express, vol. 23, no. 5, pp. 6428-6443, 2015.
Abstract | Links | BibTeX | Tags: related, testing
@article{YAO15a,
title = {Angular scan optical coherence tomography imaging and metrology of spherical gradient refractive index preforms},
author = {Yao, J. and P. Meemon and M. Ponting and J. P. Rolland},
doi = {https://doi.org/10.1364/OE.23.006428},
year = {2015},
date = {2015-03-05},
urldate = {2015-03-05},
journal = {Opt. Express},
volume = {23},
number = {5},
pages = {6428-6443},
abstract = {The fabrication of high-performance spherical gradient refractive index (S-GRIN) optics requires nondestructive metrology techniques to inspect the samples. We have developed an angular-scan, swept-source-based, Fourier-domain optical coherence tomography (OCT) system centered at 1318 nm with 5 mm imaging depth capable of 180° polar scan and 360° azimuthal scan to investigate polymeric S-GRIN preforms. We demonstrate a method that enables simultaneous mapping of the group optical thickness, physical thickness, the radially-averaged group refractive index, and the transmitted wavefront of the S-GRIN preforms. The angular scan OCT imaging and metrology enables direct visualization, molding uniformity characterization, and optical property evaluations of the preforms. The results on two generations of S-GRIN preforms are discussed that showcase the evolution of the manufacturing process in response to the OCT metrology feedback.},
keywords = {related, testing},
pubstate = {published},
tppubtype = {article}
}
The fabrication of high-performance spherical gradient refractive index (S-GRIN) optics requires nondestructive metrology techniques to inspect the samples. We have developed an angular-scan, swept-source-based, Fourier-domain optical coherence tomography (OCT) system centered at 1318 nm with 5 mm imaging depth capable of 180° polar scan and 360° azimuthal scan to investigate polymeric S-GRIN preforms. We demonstrate a method that enables simultaneous mapping of the group optical thickness, physical thickness, the radially-averaged group refractive index, and the transmitted wavefront of the S-GRIN preforms. The angular scan OCT imaging and metrology enables direct visualization, molding uniformity characterization, and optical property evaluations of the preforms. The results on two generations of S-GRIN preforms are discussed that showcase the evolution of the manufacturing process in response to the OCT metrology feedback.
2014
Thompson, K. P.; Rolland, J. P.
Cost-driven self-consistent fabrication and assembly tolerance classes Conference
Proceedings of the SPIE, vol. 9633, no. 96330U, 2014.
Abstract | Links | BibTeX | Tags: assembly, design, related
@conference{Thomsponoptifab15b,
title = {Cost-driven self-consistent fabrication and assembly tolerance classes},
author = {Thompson, K.P. and J.P. Rolland},
doi = {https://doi.org/10.1117/12.2195783},
year = {2014},
date = {2014-10-11},
urldate = {2014-10-11},
booktitle = {Proceedings of the SPIE},
volume = {9633},
number = {96330U},
abstract = {At the 1994 International Optics Design Conference, a paper was presented by the author that proposed that optics costs are often driven by the fabrication and assembly tolerances. In addition, that these tolerances fall into groups (classes) that for any given shop are set typically by the capital investment in measurement equipment that the shop has access to. The premise is then that it is essential that the optical system tolerances on fabrication, e.g. radii, element thickness, wedge, surface figure, and surface finish and on assembly e.g. component tilt and decenter and spacer thickness and wedge that are assigned by the optical designer be self-consistent with the capabilities of the shops that are solicited to provide a quotation.
In the 1994 paper, five classes of optical fabricators were identified; catalog, regular, select, premium, and ultimate (lithography). For each of these classes, representative minimum tolerances were published along with estimates of the cost increment. An important concept is that if any one tolerance falls into a tighter class, then the optical system must be built in a shop capitalized to provide that one minimum tolerance and as a result all the other tolerances can typically be moved to the tighter class with little cost impact. The primary cost impact then is driven by the class of shop dictated by the minimum tolerance. In this talk, a primary purpose is to revisit the tolerances associated with a given class of shop and update the numbers to reflect advances in the intervening two decades.},
keywords = {assembly, design, related},
pubstate = {published},
tppubtype = {conference}
}
At the 1994 International Optics Design Conference, a paper was presented by the author that proposed that optics costs are often driven by the fabrication and assembly tolerances. In addition, that these tolerances fall into groups (classes) that for any given shop are set typically by the capital investment in measurement equipment that the shop has access to. The premise is then that it is essential that the optical system tolerances on fabrication, e.g. radii, element thickness, wedge, surface figure, and surface finish and on assembly e.g. component tilt and decenter and spacer thickness and wedge that are assigned by the optical designer be self-consistent with the capabilities of the shops that are solicited to provide a quotation.
In the 1994 paper, five classes of optical fabricators were identified; catalog, regular, select, premium, and ultimate (lithography). For each of these classes, representative minimum tolerances were published along with estimates of the cost increment. An important concept is that if any one tolerance falls into a tighter class, then the optical system must be built in a shop capitalized to provide that one minimum tolerance and as a result all the other tolerances can typically be moved to the tighter class with little cost impact. The primary cost impact then is driven by the class of shop dictated by the minimum tolerance. In this talk, a primary purpose is to revisit the tolerances associated with a given class of shop and update the numbers to reflect advances in the intervening two decades.
In the 1994 paper, five classes of optical fabricators were identified; catalog, regular, select, premium, and ultimate (lithography). For each of these classes, representative minimum tolerances were published along with estimates of the cost increment. An important concept is that if any one tolerance falls into a tighter class, then the optical system must be built in a shop capitalized to provide that one minimum tolerance and as a result all the other tolerances can typically be moved to the tighter class with little cost impact. The primary cost impact then is driven by the class of shop dictated by the minimum tolerance. In this talk, a primary purpose is to revisit the tolerances associated with a given class of shop and update the numbers to reflect advances in the intervening two decades.
Yao, Jianing; Rolland, Jannick P.
Freeform Optics Metrology Using Optical Coherence Tomography Conference
Optical Fabrication and Testing, OSA 2014.
Abstract | Links | BibTeX | Tags: metrology, related
@conference{Yao2014,
title = {Freeform Optics Metrology Using Optical Coherence Tomography},
author = {Jianing Yao and Jannick P. Rolland },
doi = {https://doi.org/10.1364/OFT.2014.OW3B.4},
year = {2014},
date = {2014-06-25},
urldate = {2014-06-25},
booktitle = {Optical Fabrication and Testing},
organization = {OSA},
abstract = {We investigate the capability of a custom Fourier-domain swept-source optical coherence tomography method for non-contact freeform optics metrology. First results demonstrate the feasibility of measurement of an Alvarez surface with 400 µm sag.},
keywords = {metrology, related},
pubstate = {published},
tppubtype = {conference}
}
We investigate the capability of a custom Fourier-domain swept-source optical coherence tomography method for non-contact freeform optics metrology. First results demonstrate the feasibility of measurement of an Alvarez surface with 400 µm sag.