CeFO-Related Publications

@article{nokey,

title = {Vision ray metrology for freeform optics},

author = {Ramirez-Andrade, A.H., Shadalou, S., Gurganus, D., Davies, M.A., Suleski, T.J. and Falaggis, K},

doi = {https://doi.org/10.1364/OE.443550},

year  = {2021},

date = {2021-12-13},

urldate = {2021-12-13},

journal = {Optics Express},

volume = {29},

number = {26},

pages = {43480-4350},

abstract = {Vision ray techniques are known in the optical community to provide low-uncertainty image formation models. In this work, we extend this approach and propose a vision ray metrology system that estimates the geometric wavefront of a measurement sample using the sample-induced deflection in the vision rays. We show the feasibility of this approach using simulations and measurements of spherical and freeform optics. In contrast to the competitive technique deflectometry, this approach relies on differential measurements and, hence, requires no elaborated calibration procedure that uses sophisticated optimization algorithms to estimate geometric constraints. Applications of this work are the metrology and alignment of freeform optics.},

keywords = {metrology},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Metaform optics: Bridging nanophotonics and freeform optics},

author = {Daniel K. Nikolov and Aaron Bauer and Fei Cheng and Hitoshi Kato and A. Nick Vamivakas and Jannick P. Rolland},

url = {https://www.science.org/doi/abs/10.1126/sciadv.abe5112},

doi = {10.1126/sciadv.abe5112},

year  = {2021},

date = {2021-04-30},

urldate = {2021-04-30},

journal = {Science Advances},

volume = {7},

number = {18},

pages = {eabe5112},

abstract = {The demand for high-resolution optical systems with a compact form factor, such as augmented reality displays, sensors, and mobile cameras, requires creating new optical component architectures. Advances in the design and fabrication of freeform optics and metasurfaces make them potential solutions to address the previous needs. Here, we introduce the concept of a metaform—an optical surface that integrates the combined benefits of a freeform optic and a metasurface into a single optical component. We experimentally realized a miniature imager using a metaform mirror. The mirror is fabricated via an enhanced electron beam lithography process on a freeform substrate. The design degrees of freedom enabled by a metaform will support a new generation of optical systems.},

keywords = {Aberration correction, augmented reality, CeFO manufacturing, CEFO metrology, freeform, head display, Image quality, Optical design, relay optics, rolland, tomography},

pubstate = {published},

tppubtype = {article}

}

@article{Sahoo2020,

title = {Dynamic pulse propagation modelling for predictive femtosecond-laser-microbonding of transparent materials},

author = {Pankaj K. Sahoo and Tao Feng and Jie Qiao},

year  = {2020},

date = {2020-10-02},

journal = {Opt. Express},

volume = {28},

number = {21},

pages = {31103-31118},

abstract = {A dynamic pulse propagation modeling for femtosecond laser bonding of Borofloat glass is presented. The temperature evolution and internal modifications are predicted by incorporating the nonlinear electron dynamics along with temperature dependent thermal properties. The modelling predicts the spatial and temporal distribution of absorption coefficient and plasma density that gives quantitative estimations of the heat affected zone and weld geometry. The impact of focusing condition on heat affected zone and weld geometry is investigated, which for the first time to our knowledge allows to numerically determine the desired relative position between the geometrical focus of a femtosecond-laser-pulse and the interface of the two substrates to be welded. The prediction of the modelling on the offset distance is applied to weld Borofloat glass plates having optical contact and can be applied to other dielectric solids.},

keywords = {manufacturing, related},

pubstate = {published},

tppubtype = {article}

}

@article{Horvath19-ab,

title = {Grinding of additively manufactured silicon carbide surfaces for optical applications},

author = {Nicholas Horvath and Andrew Honeycutt and Matthew A. Davies},

url = {https://doi.org/10.1016/j.cirp.2020.04.079},

year  = {2020},

date = {2020-05-19},

journal = {CIRP Annals},

volume = {69},

pages = {509-512},

abstract = {Many of the properties of Silicon carbide (SiC) are advantageous for optical applications, such as telescope mirrors and industrial laser systems. However, the base shapes of complex components are costly and difficult to manufacture. Leveraging additive manufacturing, near net complex components are readily processed. Here, we investigate the post processing of additively manufactured SiC (AM SiC) compared to chemical vapor deposited (CVD) SiC. The specific grinding energy for the AM SiC was lower than CVD, however the trends were the same. A specular finish was observed on both materials but the AM SiC finish was limited due to residual porosity.},

keywords = {manufacturing, related},

pubstate = {published},

tppubtype = {article}

}

@article{DeMars_02,

title = {Single-Shot Phase Calibration of a Spatial Light Modulator using Geometric Phase Interferometry},

author = {L. A. DeMars and M. Mikula-Zdankowska and K. Falaggis and R. Porras-Aguilar},

year  = {2020},

date = {2020-01-01},

journal = {Appl. Opt.},

keywords = {CEFO metrology, CeFO related},

pubstate = {published},

tppubtype = {article}

}

@article{Swain2019,

title = {High-performance optical differentiation wavefront sensing towards freeform metrology},

author = {Biswa Ranjan Swain and Christophe Dorrer and Jie Qiao},

year  = {2019},

date = {2019-12-09},

journal = {Opt. Express},

volume = {27},

number = {25},

pages = {36297-36310},

abstract = {We report the demonstration of freeform optics metrology with an optical differentiation wavefront sensor that relies on spatially dithered distributions of binary pixels to synthesize a far-field amplitude filter. Analysis of experimental results and comparison with a commercial low-coherence-length interferometer shows that freeform phase plates with different magnitude of wavefront slopes can be accurately characterized. RMS accuracy of ∼ λ/10 and precision of ∼ λ/70 at 633 nm were achieved with pixelated filters having 2.5-µm pixels. Simulations that describe the characterization of a freeform optical component in the presence of photodetection noise and filter nonlinearity demonstrate the robustness of this wavefront-sensing approach for freeform optics characterization.},

keywords = {CeFO related, metrology},

pubstate = {published},

tppubtype = {article}

}

@article{lineark,

title = {Absolute linear-in-k spectrometer designs enabled by freeform optics},

author = {C. Yoon and A. Bauer and D. Xu and C. Dorrer and J. P. Rolland},

url = {https://doi.org/10.1364/OE.27.034593},

year  = {2019},

date = {2019-11-25},

journal = {Optics Express},

volume = {27},

number = {24},

pages = {34593-34602},

abstract = {Linear-in-wavenumber, k, spectrometers have the merits of saving signal processing time and improving the sensitivity of spectral-domain optical coherence tomography (SD-OCT) by avoiding post-k-interpolation. We report on an approach leveraging freeform optics to linearize spectrometers in k to achieve an extremely low residual k-nonlinearity in design. A freeform lens reduced the k-nonlinearity from 2.47% for a benchmark spectrometer to 2.79 × 10−5% and 3.36 × 10−9% using the Fringe Zernike coefficients up to the 16th term and 37th term, respectively. A simulation model was developed to evaluate the performance of SD-OCT with the designed spectrometers. Without the k-interpolation in software, results show that the two freeform spectrometers achieve a roll-off gain of 5.24 dB over the imaging depth from 0.5 to 5.5 mm, while the maximum imaging depth is 5.8 mm. Finally, a 4.2-µm-FWHM axial PSF was maintained throughout the imaging depth in air.},

keywords = {CeFO related},

pubstate = {published},

tppubtype = {article}

}

@article{Alonso2019b,

title = {Effects on the OTF of MSF structures with random variations},

author = {Kevin Liang; Miguel A. Alonso },

doi = {10.1364/OE.27.034665},

year  = {2019},

date = {2019-11-11},

journal = {Optics Express},

volume = {27},

number = {24},

pages = {34665-34680},

abstract = {In diamond-machined freeform manufacturing processes, a tool-tip often leaves behind characteristic mid-spatial frequency (MSF) structures on the optical surface. Unwanted movement between the tool-tip and the part results in MSF structures with random variations. Here, we analyze the effects of these MSF structures on the system’s optical performance and derive simple analytic estimates for the optical transfer function in terms of the parameters of these structures. These expressions are expected to aid in MSF tolerancing.},

keywords = {CeFO design},

pubstate = {published},

tppubtype = {article}

}

@article{BauerARRI,

title = {All-reflective electronic viewfinder enable by freeform optics},

author = {A. Bauer and M. Pesch and J. Muschaweck and F. Leupelt and J. P. Rolland},

url = {https://doi.org/10.1364/OE.27.030597},

year  = {2019},

date = {2019-10-14},

journal = {Optics Express},

volume = {27},

number = {21},

pages = {30597-30605},

abstract = {Refractive eyepiece design forms are often limited by chromatic aberrations and require a mix of glass types to achieve sufficient correction, thus they are not conducive to manufacture in volume. Reflective surfaces are inherently achromatic and can be produced in volume, but rotationally symmetric reflective surfaces are either used with lossy obscurations or are incapable of correcting rotationally variant aberrations when used in an unobscured form. Freeform optics enable unobscured reflective design forms with excellent image quality. Here, we document the design, fabrication, and assembly of an all-reflective high-end electronic viewfinder that shows the applicability of freeform surfaces to eyepiece design forms.},

keywords = {CeFO design, CeFO related},

pubstate = {published},

tppubtype = {article}

}

@article{TAYLOR2019,

title = {Femtosecond laser polishing of germanium},

author = {LAUREN L. TAYLOR, JING XU, MICHAEL POMERANTZ, THOMAS

R. SMITH, JOHN C. LAMBROPOULOS, AND JIE QIAO},

url = {https://doi.org/10.1364/OME.9.004165},

year  = {2019},

date = {2019-10-02},

journal = {Optical Materials Express},

volume = {9},

number = {11},

pages = {4165-4177},

abstract = {Freeform optics can reduce the cost, weight, and size of advanced imaging systems,

but it is challenging to manufacture the complex rotationally asymmetric surfaces to optical

tolerances. To address the need for disruptive, high-precision sub-aperture forming and finishing

techniques for freeform optics, we investigate an alternative, non-contact polishing methodology

using femtosecond lasers, combining modeling, experiments, and demonstrations. Femtosecondlaser-

based polishing of germanium was investigated using an experimentally-validated twotemperature

model of laser/germanium interaction to guide the understanding and selection of

laser parameters to achieve near-nonthermal ablation for polishing and figuring. For the first time

to our knowledge, model-guided femtosecond laser polishing of germanium was successfully

demonstrated, achieving precision material removal while maintaining single-digit nanometer

optical surface quality. The demonstrated femtosecond-laser-based polishing technique lays the

foundation for semiconductor optics polishing/fabrication using femtosecond lasers and opens a

viable path for high-precision, complex sub-aperture optical polishing tasks on various materials.},

keywords = {CeFO manufacturing, CEFO metrology, fabrication, Freeform surfaces, manufacturing, Mid-Spatial Frequency error},

pubstate = {published},

tppubtype = {article}

}

@article{Feng2019,

title = {Pulse-Propagation Modeling and Experiment for Femtosecond-Laser Writing of Waveguide in Nd:YAG},

author = {Tao Feng and Pankaj K. Sahoo and Francisco R. Arteaga-Sierra and Christophe Dorrer and Jie Qiao},

year  = {2019},

date = {2019-08-20},

journal = {Crystals },

volume = {9},

number = {8},

pages = {434},

abstract = {In this work, unidirectional pulse propagation equation (UPPE) modeling is performed to study the nonlinear laser-mater interaction in silicon and Nd:Y3Al5O12 (Nd:YAG) crystals. The simulation results are validated with reported experimental results for silicon and applied to Nd:YAG crystals with experimental validation. Stress-induced waveguides are written in Nd:YAG crystals using 515 nm, 300 fs pulses at a 1 kHz repetition rate. Waveguides having a mean propagation loss of 0.21 ± 0.06 dB/cm are obtained, which is lower than the previous reported values for Type-II waveguides written in Nd:YAG crystals. The modeling and experimental results consistently show that the modification (waveguide track) depth increases with input energy. A detailed analysis is presented to control the modal properties of the waveguide in the context of UPPE simulation.},

keywords = {CeFO related, manufacturing},

pubstate = {published},

tppubtype = {article}

}

@article{ALONSOALEMAN2019,

title = {Study of reflectors for illumination via conformal maps},

author = {LUIS A. ALEMÁN-CASTAÑEDA AND MIGUEL A. ALONSO},

editor = {Optical Society of America },

doi = {https://doi.org/10.1364/OL.44.003809},

year  = {2019},

date = {2019-07-02},

journal = {Optics Letters},

volume = {44},

number = {15},

pages = {3809-3812},

abstract = {We present an approach for the study and design of reflectors with rotational or translational symmetry that redirect light from a point source into any desired radiant intensity distribution. This method is based on a simple conformal map that transforms the reflector’s shape into a curve that describes light’s direction after reflection. Both segmented reflectors and continuous reflectors are discussed, illustrating how certain reflector characteristics become apparent under this transformation. This method can also be used to study extended sources via translations.},

keywords = {design, related},

pubstate = {published},

tppubtype = {article}

}

@article{DeMars_01,

title = {Calibration of an SLM using Geometric Phase Interferometry},

author = {L. A. DeMars and K. Falaggis and R. Porras-Aguilar },

year  = {2019},

date = {2019-06-01},

journal = {RIAO-OPTILAS-MOPM},

keywords = {CEFO metrology, CeFO related},

pubstate = {published},

tppubtype = {article}

}

@article{Mishchik2019,

title = {High-efficiency femtosecond ablation of silicon with GHz repetition rate laser source},

author = {Konstantin Mishchik and Guillaume Bonamis and Jie Qiao and John Lopez and Eric Audouard and Eric Mottay and Clemens Hönninger and Inka Manek-Hönninger},

year  = {2019},

date = {2019-05-01},

journal = {Opt. Lett.},

volume = {44},

number = {9},

pages = {2193-2196},

abstract = {We report on silicon ablation with a 20 W GHz amplified femtosecond laser source. This novel laser delivers burst energies up to 400 μJ, providing flexible intra-pulse repetition rates of 0.88 or 3.52 GHz, up to 200 pulses with ∼350 fs pulse duration. High-efficiency, high-quality ablation can be achieved through optimally determining the number of pulses, intra-pulse repetition, and average pulse energy within a burst. Due to such optimization, we demonstrate a specific ablation rate of 2.5 mm3∕ min ∕W with a burst containing 200 pulses at 0.88 GHz, which is the highest one reported so far for fs laser ablation, to the best of our knowledge. GHz ablation is sensitive to the selection of laser parameters. We conceptually discuss the contributions of the pulses within a burst to heat-accumulation-based incubation and material ablation.},

keywords = {CeFO related, manufacturing},

pubstate = {published},

tppubtype = {article}

}

@article{ALEMÁN-CASTANEDA2019,

title = {Shearing interferometry via geometric phase},

author = {LUIS A. ALEMÁN-CASTANEDA, BRUNO PICCIRILLO, ENRICO SANTAMATO, LORENZO MARRUCCI, AND MIGUEL A. ALONSO},

url = {https://doi.org/10.1364/OPTICA.6.000396},

doi = {10.1364/OPTICA.6.000396},

year  = {2019},

date = {2019-03-21},

journal = {Optica},

volume = {6},

number = {4},

pages = {396-399},

abstract = {We propose an approach based on geometric phase for per- forming several types of shearing interferometry through a ro- bust, compact, common-path setup. The key elements are two identical parallel plates with spatially varying birefringence distributions, which perform the shearing by writing opposite geometric phases on the two circular polarization components of the linearly polarized incident wavefront. This setup allows the independent control of the shearing magnitude and rela- tive phase of the two wavefront replicas. The approach is first illustrated for the simplest case of lateral shearing, and then extended to other geometries where the magnitude and direc- tion of the shear vary smoothly over the wavefront.},

keywords = {metrology, related},

pubstate = {published},

tppubtype = {article}

}

@article{Schiesser2018,

title = {Gaussian curvature and stigmatic imaging relations for the design of an unobscured reflective relay},

author = {Eric M. Schiesser and Seung-Whan Bahk and Jake Bromage and Jannick P. Rolland},

url = {https://doi.org/10.1364/OL.43.004855},

doi = {10.1364/OL.43.004855},

year  = {2018},

date = {2018-10-03},

journal = {Optics Letters},

number = {20},

pages = {4855-4858},

abstract = {We derive the relationship between Coddington's equations and the Gaussian curvature for a stigmatic reflective imaging system. This relationship allows parameterizing off-axis conic optical systems using traditional first-order optics by considering the effective curvature at the center of the off-axis sections. Specifically, we demonstrate parameterizing the system requirements of a 2{\texttimes} achromatic image relay for a terawatt laser system. This system required both collimation (far-field) and pupil imaging (near-field) simultaneously. Long working distances and specific spatial constraints limited the available layout options for the imaging components. By parameterizing these system requirements and packaging constraints, the final specifications could be quickly iterated, while allowing for flexibility in the layout of the system during a multi-year conceptual period.},

keywords = {CeFO related, design},

pubstate = {published},

tppubtype = {article}

}

@article{Papa_IODC2017,

title = {Starting point designs for freeform four-mirror systems},

author = {Jonathan C. Papa and J. Howard and J. P. Rolland},

url = {https://doi.org/10.1117/1.OE.57.10.101705},

doi = {10.1117/1.OE.57.10.101705},

year  = {2018},

date = {2018-06-21},

journal = {Optical Engineering},

volume = {57},

number = {10},

pages = {101705},

abstract = {Driven by the development of freeform four-mirror solutions, we review and 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. 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 in these starting point designs are described as base off-axis conics that image stigmatically for the central field point, also known as Cartesian reflectors, with an aspheric departure “cap” (quartic with the aperture) added to the Cartesian reflectors. Tilt angles are chosen to cancel field-asymmetric field-linear astigmatism and unobscure the system. Paraxial data from an equivalent on-axis system are used to solve a system of linear equations to determine the magnitude of the aspheric departure “caps” that are placed on top of the base Cartesian reflectors, in order to eliminate the remaining third-order image degrading aberrations. In this approach, each aspheric departure “cap” is centered about the intersection of the optical-axis-ray, also known as the base ray, with the base surface, rather than being centered about the axis of rotational invariance.},

keywords = {CeFO related, design},

pubstate = {published},

tppubtype = {article}

}

@article{LaurenApp18,

title = {Direct binary search for improved beam shaping and optical differentiation wavefront sensing},

author = {C. Dorrer and J. Qiao},

doi = {https://www.osapublishing.org/ao/abstract.cfm?URI=ao-57-29-8557},

year  = {2018},

date = {2018-06-01},

journal = {Applied Optics},

volume = {57 (29)},

pages = {8557-8565 },

keywords = {CeFO related, manufacturing, related},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@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}

}

@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://www.osapublishing.org/ome/abstract.cfm?URI=ome-8-3-648},

year  = {2018},

date = {2018-03-01},

journal = {Optical Materials Express},

volume = {8},

number = {3},

pages = {648-658},

keywords = {CeFO related, manufacturing},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@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},

year  = {2016},

date = {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}

}

@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},

year  = {2016},

date = {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}

}

@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},

year  = {2016},

date = {2016-04-15},

journal = {Optics Letters},

volume = {41},

number = {9},

pages = {1981-1984 },

keywords = {related, testing},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@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}

}