CeFO Publications

@article{romita_2022,

title = {Implementation of a null test for freeform optics using a high-definition spatial light modulator},

author = {R. Chaudhuri and A. Wansha and R. Porras-Aguilar and J. P. Rolland},

doi = {https://doi.org/10.1364/OE.473853},

year  = {2022},

date = {2022-11-21},

urldate = {2022-11-21},

journal = {Optics Express},

volume = {30},

issue = {24},

pages = {43938-43960},

abstract = {We report the implementation of an interferometric null test using a high-definition spatial light modulator (SLM) as a reconfigurable alternative to a computer-generated hologram. We detail the alignment process chain, including novel techniques using the SLM to project alignment fiducials on the test part. To validate the alignment protocol, we measure a mild off-axis conic with the SLM-based system and cross-validate with conventional interferometry within 30 nm root-mean-square (RMS) surface figure. Finally, we report the null test of a 65 mm clear aperture concave freeform with 91 μm peak-valley sag departure from the base sphere. The measured surface figure of the freeform is within 40 nm RMS compared to the measurement with a commercial metrology instrument.},

keywords = {CeFO, CEFO 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{XU2021b,

title = {Verification of cascade optical coherence tomography for freeform optics form metrology},

author = {Di Xu,,* Zhenkun Wen, Andres Garcia Coleto, Michael

Pomerantz, John C. Lambropoulos, 2 and Jannick P.

Rolland},

url = {https://opg.optica.org/oe/fulltext.cfm?uri=oe-29-6-8542&id=448922},

doi = {https://doi.org/10.1364/OE.413844},

year  = {2021},

date = {2021-03-05},

urldate = {2021-03-05},

journal = {Optics Express},

volume = {29},

number = {6},

pages = {8542-8552},

abstract = {Freeform optical components enable dramatic advances for optical systems in both

performance and packaging. Surface form metrology of manufactured freeform optics remains

a challenge and an active area of research. Towards addressing this challenge, we previously

reported on a novel architecture, cascade optical coherence tomography (C-OCT), which was

validated for its ability of high-precision sag measurement at a given point. Here, we demonstrate

freeform surface measurements, enabled by the development of a custom optical-relay-based

scanning mechanism and a unique high-speed rotation mechanism. Experimental results on a flat

mirror demonstrate an RMS flatness of 14 nm (∼λ/44 at the He-Ne wavelength). Measurement

on a freeform mirror is achieved with an RMS residual of 69 nm (∼λ/9). The system-level

investigations and validation provide the groundwork for advancing C-OCT as a viable freeform

metrology technique.

},

keywords = {CeFO, CEFO metrology, coherence, freeform, tomography},

pubstate = {published},

tppubtype = {article}

}

@article{dixu2021,

title = {Cascade optical coherence tomography (C-OCT)},

author = {D. Xu and A. G. Coleto and B. Moon and J. C. Papa and M. Pomerantz and J. P. Rolland },

doi = {https://doi.org/10.1364/OE.394638},

year  = {2020},

date = {2020-07-06},

journal = {Optics Express},

volume = {28},

number = {14},

pages = {19937-19953},

abstract = {Significant advances for optical systems in terms of both performance and packaging are enabled by freeform optical components. Yet, surface form metrology for freeform optics remains a challenge. We developed and investigated a point-cloud cascade optical coherence tomography (C-OCT) technique to address this metrology challenge. The mathematical framework for the working principle of C-OCT is presented. A novel detection scheme is developed to enable high-speed measurements. Experimental results validate the C-OCT technique with the prototype setup demonstrating single-point precision of ±26 nm (∼λ/24 at the He-Ne wavelength), paving the way towards full surface measurements on freeform optical components.},

keywords = {CeFO, CEFO metrology},

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},

doi = {https://doi.org/10.1364/AO.383610},

year  = {2020},

date = {2020-01-01},

urldate = {2020-01-01},

journal = {Appl. Opt.},

volume = {59},

issue = {13},

pages = {D125-D130},

abstract = {A vibration-insensitive, single-shot phase-calibration method for phase-only spatial light modulators (SLM) is reported. The proposed technique uses a geometric phase lens to form a phase-shifting radial shearing interferometer to enable common-path measurements. This configuration has several advantages: (a) unlike diffraction-based SLM calibration techniques, this technique is robust against intensity errors due to misalignment; (b) unlike two-beam interferometers, this technique offers a high environmental stability; and (c) unlike intensity-based methods, the phase-shifting capability provides a phase uncertainty routinely in the order of 2𝜋/100

. The experimental results show a significantly higher accuracy when compared to the diffraction-based approaches.},

keywords = {CEFO metrology, 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{Horvath19-a,

title = {Kinematic mirror mount design for ultra-precision manufacturing, metrology, and system level integration for high performance visible spectrum imaging systems},

author = {Nicholas W. Horvath and Matthew A. Davies and Steven R. Patterson},

url = {https://doi.org/10.1016/j.precisioneng.2019.09.011},

year  = {2019},

date = {2019-09-20},

journal = {Precision Engineering},

volume = {60},

pages = {535-543},

abstract = {High-performance freeform optical systems, designed for broad spectral imaging from the visible to the far infrared, place new demands on optical design, precision manufacturing, and precision metrology. To meet the tolerances on figure, roughness, and relative positioning in such systems requires the ability to perform metrology and manufacturing corrections on freeform optics in a continuous feedback loop. This feedback loop requires a common interface for machining and manufacturing platforms. This paper describes the design, analysis, and testing of such an interface suitable for use with single point diamond turning and deterministic micro-grinding. The interface utilizes a torsionally preloaded, robust, kinematic mount capable of supporting manufacturing process loads while maintaining the position repeatability in five degrees of freedom required for the measurement and correction of optical figure. Results from a prototype system demonstrate absolute in-plane position uncertainty less than 200 nm and 50 nm, respectively, and axial position uncertainty is 40 nm absolute and 10 nm relative. The absolute and relative angular positioning uncertainties less than 1 µrad and 0.25 µrad respectively. The results exceed the requirements for many optical systems. The mount is also suitable for use in opto-mechanical assembly, so that the same platform can be used for manufacturing, metrology, final assembly, testing, and service.},

keywords = {CeFO, CeFO manufacturing, CEFO metrology, Freeform surfaces, Kinematic Coupling},

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{Vendittia2019,

title = {Design for metrology for freeform optics manufacturing},

author = {Kristen Vendittia and Chris Evans and Konstantinos Falaggis and Alex Blum and Romita Chaudhuri and Jeremy Goodsell and Jannick P. Rolland},

url = {https://www.sciencedirect.com/science/article/pii/S2212827119309023},

year  = {2019},

date = {2019-05-08},

journal = {ScienceDirect},

volume = {29},

number = {84},

pages = {169-172},

publisher = { Elsevier B.V.},

organization = {ScienceDirect},

abstract = {Freeform optical surfaces offer significant design opportunities but pose new challenges in metrology and manufacturing. Evolution in optics manufacturing processes have changed the surface spatial frequencies that must be measured. Optical surface definition is expected to be with respect to fiducials and datums which must be realizable at all stages of manufacture; uncertainty in that realization becomes important in some cases. Concurrent engineering is required, but appropriate data has not been collated for use by optical designers. One approach to providing such data is described.},

keywords = {CeFO, CEFO metrology},

pubstate = {published},

tppubtype = {article}

}

@article{Michalko18,

title = { Verification of transverse translation diverse phase retrieval for concave optical metrology},

author = {A. M. Michalko and J. R. Fienup},

editor = {Optical Society of America},

url = {https://doi.org/10.1364/OL.43.004827},

doi = {10.1364/OL.43.004827},

year  = {2018},

date = {2018-10-01},

journal = {Optics Letters},

volume = {43},

number = {19},

pages = {4827-4830},

abstract = {The surface figure error of a concave spherical mirror was measured using transverse translation diverse phase retrieval (TTDPR), an image-based wavefront sensing technique. Good reproducibility of the surface measurement is demonstrated. Additionally, the TTDPR measurement of the surface, with certain alignment terms removed, is shown to agree with interferometric measurements to 0.0060 waves root mean square.},

keywords = {CeFO, CEFO metrology},

pubstate = {published},

tppubtype = {article}

}

@article{Michalko2018b,

title = {Transverse translation diverse phase retrieval using soft-edged illumination},

author = {A. M. Michalko and J. R. Fienup},

editor = {Optical Society of America},

url = {https://doi.org/10.1364/OL.43.001331},

doi = {10.1364/OL.43.001331},

year  = {2018},

date = {2018-03-14},

journal = {Optics Letters},

volume = {43},

number = {6},

pages = {1331-1334},

abstract = {Transverse translation diverse phase retrieval (TTDPR), a ptychographic image-based wavefront-sensing technique, is a viable method for optical shop testing due to its high accuracy and relatively simple experimental arrangement. However, when measuring a reflective optic, a normally hard-edged translating illumination will become soft-edged due to diffraction, which may reduce the accuracy of TTDPR by suppressing fine structures in measured data. In this Letter, we quantitatively explore the wavefront-sensing accuracy of TTDPR in the presence of soft-edged translating illumination.},

keywords = {CeFO, CEFO metrology, metrology},

pubstate = {published},

tppubtype = {article}

}

@article{Owen2017,

title = {Error correction methodology for ultra-precision three-axis milling of freeform optics},

author = {J.D. Owen and J.A. Shultz and T.J. Suleski and M.A. Davies},

url = {https://doi.org/10.1016/j.cirp.2017.04.031},

year  = {2017},

date = {2017-05-02},

journal = {CIRP Annals},

volume = {66},

number = {1},

pages = {97-100},

abstract = {Freeform optics facilitate a revolutionary approach to optical design. Ultra-precision diamond machining is an enabling technology for the manufacture of freeform optics. However, optical designs require tight tolerances across spatial wavelengths ranging from micro-roughness to overall form. To manufacture freeform optics to the necessary tolerances, a novel artifact-based error reduction methodology applicable to multi-axis diamond milling was developed. As demonstrated on a test sphere, the methodology reduces dominant error sources on the test sphere surface from 194 to 40 nm RMS. The approach is then successfully applied to an example freeform optical design where comparable error levels are achieved.},

keywords = {CeFO, CeFO manufacturing, CEFO metrology},

pubstate = {published},

tppubtype = {article}

}