2018
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 Proceedings
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.
Lambropoulos, John C.; Salzman, Sivan; Smith, Thomas R.; Xu, Jing; Pomerantz, Michael; Shanmugam, Prithiviraj; Davies, Matt; Taylor, Lauren L.; Qiao, Jie
Subsurface Damage (SSD) Assessment in Ground Silicon Carbide (SiC) Proceedings
OSA, vol. Optical Fabrication and Testing, no. Paper# OM3B.5 , 2017.
Abstract | BibTeX | Tags: CeFO, CeFO manufacturing, CeFO related
@proceedings{Lambropoulos171,
title = {Subsurface Damage (SSD) Assessment in Ground Silicon Carbide (SiC)},
author = {Lambropoulos, John C. and Salzman, Sivan and Smith, Thomas R. and Xu, Jing and Pomerantz, Michael and Shanmugam, Prithiviraj and Davies, Matt and Taylor, Lauren L. and Qiao, Jie},
year = {2017},
date = {2017-07-20},
volume = {Optical Fabrication and Testing},
number = {Paper# OM3B.5 },
publisher = {OSA},
abstract = {We assess subsurface damage in ground Silicon Carbide, by measurement of roughness evolution and material removal rate in sub-aperture finished spots, or by estimates via material property figures of merit or abrasive size used for grinding.},
keywords = {CeFO, CeFO manufacturing, CeFO related},
pubstate = {published},
tppubtype = {proceedings}
}
We assess subsurface damage in ground Silicon Carbide, by measurement of roughness evolution and material removal rate in sub-aperture finished spots, or by estimates via material property figures of merit or abrasive size used for grinding.
Qiao, J.; Dorrer, C.
Measuring wavefront by optical differentiation with binary pixelated filters Proceedings
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.