CeFO Publications

@article{DeMars23a,

title = {Pupil-difference moments for estimating relative modulation from general mid-spatial frequency surface errors},

author = {L. A. DeMars and T.J. Suleski},

doi = {https://doi.org/10.1364/OL.491408},

year  = {2023},

date = {2023-05-01},

urldate = {2023-05-01},

journal = {Optics Letters},

volume = {48},

issue = {9},

pages = {2492-2495},

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

pubstate = {published},

tppubtype = {article}

}

@article{Moein23a,

title = {Fabrication and characterization of freeform phase plates for extended depth of field imaging},

author = {S. Moein and D. Gurganus and M. A. Davies and G.D. Boreman and T.J. Suleski},

doi = {https://doi.org/10.1364/OPTCON.480895},

year  = {2023},

date = {2023-03-27},

urldate = {2023-03-27},

journal = {Optics Continuum},

volume = {2},

issue = {4},

pages = {769-782},

keywords = {CeFO, design, manufacturing, metrology, testing},

pubstate = {published},

tppubtype = {article}

}

@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{Shadalou22b,

title = {Design, fabrication, and characterization of a tunable LED-based illuminator using refractive freeform arrays},

author = {S. Shadalou and D. Gurganus and W. J. Cassarly and M. A. Davies and T.J. Suleski},

doi = {https://doi.org/10.1364/OE.474842},

year  = {2022},

date = {2022-11-04},

urldate = {2022-11-04},

journal = {Optics Express},

volume = {30},

number = {23},

pages = {42749-42761},

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

pubstate = {published},

tppubtype = {article}

}

@article{Chen2022,

title = {Femtosecond-laser-enabled simultaneous figuring and finishing of glass with a subnanometer optical surface},

author = {Gong Chen and Jie Qiao},

url = {https://opg.optica.org/ol/fulltext.cfm?uri=ol-47-15-3860&id=481949},

year  = {2022},

date = {2022-07-26},

urldate = {2022-07-26},

journal = {Optics Letters},

volume = {47},

issue = {15},

pages = {3860-3863},

abstract = {We demonstrate simultaneous figuring and surface finishing

of glass using a femtosecond laser. For the first time, to

the best of our knowledge, we have achieved deterministic

material removal with nanometer precision and maintained

sub-nanometer surface roughness without inducing

any mid-spatial-frequency errors to the initial surface. A

dynamic pulse propagation model is established to predict

the interaction process, including plasma generation

and surface temperature. The interactive modeling and the

experiments enable the selection of a set of laser parameters

to achieve controllable optical figuring and finishing.

This demonstration shows the potential for using femtosecond

lasers for advanced freeform optic forming, finishing,

and reduction of detrimental mid-spatial-frequency errors,

and laser-ablation-based patterning used for fabrication of

integrated photonics and lasers.},

keywords = {CeFO, fabrication},

pubstate = {published},

tppubtype = {article}

}

@article{Moein22a,

title = {PSF engineering with variable logarithmic phase plates for the extended depth of field},

author = {S. Moein and S. Shadalou and T.J. Suleski},

doi = {https://doi.org/10.1364/OPTCON.465138},

year  = {2022},

date = {2022-07-07},

urldate = {2022-07-07},

journal = {Optics Continuum},

volume = {1},

pages = {1579-1592},

keywords = {CeFO, design},

pubstate = {published},

tppubtype = {article}

}

@article{Shadalou22a,

title = {General design method for dynamic freeform optics with variable functionality},

author = {S. Shadalou and T.J. Suleski},

doi = {https://doi.org/10.1364/OE.460078},

year  = {2022},

date = {2022-05-19},

journal = {Optics Express},

volume = {30},

issue = {11},

pages = {19974-19989},

keywords = {CeFO, design},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Vision ray metrology for freeform optics},

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

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 = {CeFO, metrology},

pubstate = {published},

tppubtype = {article}

}

@article{kim_OE21,

title = {Connecting tolerancing of freeform surface deformation in illumination optics with the Laplacian magic mirror},

author = {W. Kim and W. J. Cassarly and J. P. Rolland},

doi = {https://doi.org/10.1364/OE.442853},

year  = {2021},

date = {2021-11-22},

journal = {Optics Express},

volume = {29},

issue = {24},

pages = {40559-40571},

abstract = {This paper presents a methodology for illumination optics tolerancing. Specifically, we investigate tolerancing deformation of a single freeform surface under a point source illumination. Through investigation, we recognized and report here three surface-deformation characteristics that build tolerancing intuitions. First, we show that positive and negative irradiance changes occur together as a consequence of flux conservation. Then, we demonstrate a linear relationship between the steepness of the surface perturbation and the magnitude of the irradiance change. Lastly, we show that the Laplacian magic mirror concept (M. V. Berry [Eur. J. Phys. 27, 109 (2006)) can be expanded to surface deformation tolerancing. Utilizing these surface deformation characteristics, we propose a fast and predictable tolerancing method for a sequential illumination},

keywords = {CeFO, Illumination},

pubstate = {published},

tppubtype = {article}

}

@article{Moein2021-2,

title = {Freeform optics for variable extended depth of field imaging },

author = {S. Moein and T. J. Suleski},

url = {https://opg.optica.org/oe/fulltext.cfm?uri=oe-29-24-40524&id=464994},

year  = {2021},

date = {2021-11-19},

urldate = {2021-11-19},

journal = {Optics Express},

volume = {29},

number = {24},

pages = {40524-40537},

abstract = {Imaging depth of field is shallow in applications with high magnification and high numerical aperture, such as microscopy, resulting in images with in- and out-of-focus regions. Therefore, methods to extend depth of field are of particular interest. Researchers have previously shown the advantages of using freeform components to extend depth of field, with each optical system requiring a specially designed phase plate. In this paper we present a method to enable extended depth-of-field imaging for a range of numerical apertures using freeform phase plates to create variable cubic wavefronts. The concept is similar to an Alvarez lens which creates variable spherical wavefronts through the relative translation of two transmissive elements with XY polynomial surfaces. We discuss design and optimization methods to enable extended depth of field for lenses with different numerical aperture values by considering through-focus variation of the point spread function and compare on- and off-axis performance through multiple metrics.},

keywords = {CeFO, CeFO design, imaging},

pubstate = {published},

tppubtype = {article}

}

@article{liu_cubesat_21,

title = {Freeform hyperspectral imager design in a CubeSat format},

author = {Y. Liu and A. Bauer and J. P. Rolland},

doi = {https://doi.org/10.1364/OE.439530},

year  = {2021},

date = {2021-10-25},

journal = {Optics Express},

volume = {29},

issue = {22},

pages = {35915-35928},

abstract = {A freeform pushbroom hyperspectral imager design was investigated as a combination of a freeform reflective triplet imager and a freeform reflective triplet spectrometer used in double-pass. The design operates at about F/2 with a 15-degree cross-track field-of-view and a 30 mm entrance pupil diameter. The design process led to achieving a small volume of less than 2 liters that fits comfortably within a 3U CubeSat geometry, exemplifying the compactness of this hyperspectral imager. We report the freeform sag departures and maximum slopes of the freeform surfaces, as well as the manufacturing tolerances together with an evaluation of the system stray light, all of which highlight the feasibility of a design in this class to be manufactured. This design uniquely positions itself on the landscape of compact hyperspectral imagers.},

keywords = {CeFO, CeFO design},

pubstate = {published},

tppubtype = {article}

}

@article{bauer_21,

title = {Roadmap for the unobscured three-mirror freeform design space},

author = {Aaron Bauer and Jannick P. Rolland},

doi = {https://doi.org/10.1364/OE.433643},

year  = {2021},

date = {2021-08-03},

urldate = {2021-08-03},

journal = {Optics Express},

volume = {29},

number = {17},

pages = {26736-26744},

abstract = {In rotationally symmetric lens design, there are rule-of-thumb boundaries on field-of-view and aperture for well-known design forms that provide valuable information to the designer prior to starting a design. In the design space of unobscured three-mirror imagers, freeform optics have been shown to provide a significant benefit over conventional surface shapes, but the degree to which they improve the performance for any given combination of field-of-view, entrance pupil diameter, and F-number remains unknown. Thus, designers of these systems are not afforded any pre-design information to inform their specification decisions. Here, we designed over 200 systems to establish a first-of-its-kind roadmap of specification ranges over which an unobscured three-mirror imager using freeform surfaces can achieve diffraction-limited performance in the visible spectrum. The scalability of the findings to the infrared regions of the spectrum is also addressed.},

keywords = {CeFO, CeFO design},

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{ffreview21,

title = {Freeform optics for imaging },

author = {J. P. Rolland and M. A. Davies and T. J. Suleski and C. Evans and A. Bauer and J. C. Lambropoulos and K. Falaggis },

url = {https://opg.optica.org/optica/fulltext.cfm?uri=optica-8-2-161&id=447006},

year  = {2021},

date = {2021-02-01},

urldate = {2021-02-01},

journal = {Optica},

volume = {8},

number = {2},

pages = {161-176},

abstract = {In the last 10 years, freeform optics has enabled compact and high-performance imaging systems. This article begins with a brief history of freeform optics, focusing on imaging systems, including marketplace emergence. The development of this technology is motivated by the clear opportunity to enable science across a wide range of applications, spanning from extreme ultraviolet lithography to space optics. Next, we define freeform optics and discuss concurrent engineering that brings together design, fabrication, testing, and assembly into one process. We then lay out the foundations of the aberration theory for freeform optics and emerging design methodologies. We describe fabrication methods, emphasizing deterministic computer numerical control grinding, polishing, and diamond machining. Next, we consider mid-spatial frequency errors that inherently result from freeform fabrication techniques. We realize that metrologies of freeform optics are simultaneously sparse in their existence but diverse in their potential. Thus, we focus on metrology techniques demonstrated for the measurement of freeform optics. We conclude this review with an outlook on the future of freeform optics.},

keywords = {CeFO},

pubstate = {published},

tppubtype = {article}

}

@article{Shadalou2021_3,

title = {Tunable illumination for LED-based systems using refractive freeform arrays},

author = {Shohreh Shadalou and William J. Cassarly and Thomas J. Suleski},

url = {https://doi.org/10.1364/OE.441304},

doi = {10.1364/OE.441304},

year  = {2021},

date = {2021-00-00},

urldate = {2021-00-00},

journal = {Optics Express},

volume = {29},

number = {22},

pages = {35755-35764},

abstract = {Tunable illumination with high uniformity can improve functionality for multiple application areas. In lighting applications, dynamic illumination has been achieved by applying axial movement to the source(s) or other optical elements, resulting in poor uniformity, or using a liquid lens that adds design complexity. Advances in high-precision manufacturing methods have facilitated the practical implementation of freeform optical components, enabling new design approaches for illumination systems. This paper explores the use of arrays of varifocal transmissive freeform Alvarez lenses for an LED-based illumination system. The design is initialized using paraxial geometrical optics concepts and then refined for a 1mm-by−1 mm white LED source through a multi-step optimization. Design procedures are discussed, and simulation results are presented for an example illumination system that varies from a small circular spot mode to a large square uniform flood mode through millimeter-scale lateral translation between the Alvarez lens arrays.},

keywords = {CeFO, CeFO design, freeform, Illumination},

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{takaki2020,

title = {Off-axis conics as base surfaces for freeform optics enable null testability},

author = {N. Takaki and J. C. Papa and A. Bauer and J. P. Rolland},

doi = {https://doi.org/10.1364/OE.389426},

year  = {2020},

date = {2020-04-13},

journal = {Optics Express},

volume = {28},

number = {8},

pages = {10859-10872},

abstract = {When conducting interferometric tests of freeform optical surfaces, additional optical components, such as computer-generated holograms or deformable mirrors, are often necessary to achieve a null or quasi-null. These additional optical components increase both the cost and the difficulty of interferometric tests of freeform optical surfaces. In this paper, designs using off-axis segments of conics as base surfaces for freeforms are explored. These off-axis conics are more complex base surfaces than typically-used base spheres but remain null-testable. By leveraging off-axis conics in conjunction with additional orthogonal polynomial departures, designs were found with up to an order-of-magnitude of improvement in testability estimates relative to designs that use base spheres. Two design studies, a three-mirror telescope and a wide field-of-view four-mirror telescope, demonstrate the impact of using off-axis conics as the base surface.},

keywords = {CeFO, CeFO design},

pubstate = {published},

tppubtype = {article}

}

@article{Schiess2_2019,

title = {Estimating field-dependent nodal aberration theory coefficients from Zernike full-field displays by utilizing eighth-order astigmatism},

author = {E. M. Schiesser and A. Bauer and J. P. Rolland},

url = {

https://doi.org/10.1364/JOSAA.36.002115

},

year  = {2019},

date = {2019-12-13},

journal = {JOSA A},

volume = {36},

number = {12},

pages = {2115-2128},

abstract = {When using freeform surfaces in optical design, the field dependence of the aberrations can become quite complex, and understanding these aberrations facilitates the design process. Here we calculate the field dependence of low-order Zernike astigmatism (Z5/6) up to the eighth order in nodal aberration theory (NAT). Expansion of NAT astigmatism terms to the eighth order facilitates a more accurate fit to the Zernike astigmatism data. We then show how this estimated field dependence can be used to quantitatively analyze a freeform telescope design. This analysis tool adds to the optical designer’s arsenal when up against the challenge of designing with freeform optics.},

keywords = {CeFO, design},

pubstate = {published},

tppubtype = {article}

}

@article{Aryan2019e,

title = {Simple methods for estimating the performance and specification of optical components with anisotropic mid-spatial frequency surface errors},

author = {Hamidreza Aryan and Glenn D. Boreman and Thomas J. Suleski},

url = {https://doi.org/10.1364/OE.27.032709},

doi = {https://doi.org/10.1364/OE.27.032709},

year  = {2019},

date = {2019-10-25},

journal = {Optics Express},

volume = {27},

number = {22},

pages = {32709-32721 },

keywords = {CeFO, CeFO manufacturing, manufacturing, Mid-Spatial Frequency error},

pubstate = {published},

tppubtype = {article}

}

@article{Alonso2019,

title = {Rapidly decaying Fourier-like bases},

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

editor = {OSA},

doi = {10.1364/OE.27.032263},

year  = {2019},

date = {2019-10-23},

journal = {Optics Express},

volume = {27},

number = {22},

pages = {32263-32276},

abstract = {In many applications it is natural to seek to extract a characteristic scale for a function’s variations by reference to a frequency spectrum. Although the moments of a spectrum appear to promise simple options to make such a connection, standard Fourier methods fail to yield finite moments when the function’s domain is itself finite. We investigate a family of Fourier-like bases with rapidly decaying spectra that yield well-defined moments for such cases. These bases are derived by considering classes of functions for which a normalised mean square derivative is stationary. They are shown to provide precisely the type of spectrum needed to complete a recent investigation of mid-spatial frequency structure on optical surfaces [K. Liang, Opt. Express 27, 3390-3408 (2019)].},

keywords = {CeFO, design},

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{Aryan2019d,

title = {The Minimum Modulation Curve as a tool for specifying optical performance: application to surfaces with mid-spatial frequency errors},

author = {Hamidreza Aryan and Glenn D. Boreman and Thomas J. Suleski},

url = {https://doi.org/10.1364/OE.27.025551},

doi = {https://doi.org/10.1364/OE.27.025551},

year  = {2019},

date = {2019-08-23},

journal = {Optics Express},

volume = {27},

number = {18},

pages = {25551-25559},

keywords = {CeFO, CeFO manufacturing, Mid-Spatial Frequency error},

pubstate = {published},

tppubtype = {article}

}

@article{Schiess1_2019,

title = {Effect of freeform surfaces on the volume and performance of unobscured three mirror imagers in comparison with off-axis rotationally symmetric polynomials},

author = {E. M. Schiesser and A. Bauer and J. P. Rolland},

url = {https://doi.org/10.1364/OE.27.021750},

year  = {2019},

date = {2019-07-25},

journal = {Optics Express},

volume = {27},

number = {15},

pages = {21750-21765},

abstract = {The invention of new design techniques for unobscured reflective systems using freeform surfaces has expanded the optical design space for these system types. We illustrate how the use of freeform surfaces can expand the design space of the Three Mirror Compact design type to allow both better performance at a given system volume and smaller volumes for a given performance target. By evolving designs using conventional off-axis asphere type surfaces to ever smaller volumes and then converting these off-axis asphere descriptions to centered Zernike descriptions, we show that the wavefront error improves by up to 69% in this case by allowing the surfaces to break rotational symmetry. In addition, we show that evolving designs from the same starting point as the off-axis asphere designs but instead using a centered Zernike description can produce a design with a 39% smaller volume in this case while maintaining the same diffraction-limited performance.},

keywords = {CeFO, design},

pubstate = {published},

tppubtype = {article}

}