Dr. Heejoo Choi Profile

Dr. Heejoo Choi

Assistant Research Professor

SPIE Involvement:

Conference Chair | Author | Editor

Area of Expertise:

Optical testing , Optical manufacturing , Optical engineering

Publications (64)

Proceedings Article | 5 October 2023 Presentation

Ultralightweight hybrid refractive/diffractive MODE telescopes for space applications

Thomas Milster, Nick Brar, Yingying Zhang, Young-Sik Kim, Heejoo Choi, Marcos Esparza, Daewook Kim, Allen Yi, Yuxin Cai, Geonhee Kim, Daniel Apai

Proceedings Volume PC12677, PC126770G (2023) https://doi.org/10.1117/12.2677762

KEYWORDS: Telescopes, Optical alignment, Space telescopes, Optical fabrication, Lenses, Fabrication, Wavefronts, Stray light, Spectroscopy, Space mirrors

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Proceedings Article | 5 October 2023 Presentation

Tolerance and alignment study of two-channel telescope spectroscopy for Aspera

Heejoo Choi, Haeun Chung, Carlos Vargas, Aafaque Khan, Jason Corliss, Daewook Kim

Proceedings Volume PC12677, PC126770D (2023) https://doi.org/10.1117/12.2678100

KEYWORDS: Telescopes, Spectroscopy, Optical alignment, Computer generated holography, Microchannel plates, Extreme ultraviolet, Tolerancing, Optical gratings, Galactic astronomy, Satellites

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Proceedings Article | 4 October 2023 Presentation + Paper

Approaches to developing tolerance and error budget for active three mirror anastigmat space telescopes

Heejoo Choi, Young-Sik Kim, Hyukmo Kang, Solvay Blomquist, Hill Tailor, Douglas Kelly, Mike Eiklenborg, Ewan Douglas, Daewook Kim

Proceedings Volume 12677, 126770F (2023) https://doi.org/10.1117/12.2677986

KEYWORDS: Tolerancing, Received signal strength, Telescopes, Mirrors, Wavefront errors, Observatories, Space mirrors, Space telescopes, Optical surfaces, Optical design

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Proceedings Article | 4 October 2023 Presentation + Paper

Integrated modeling of wavefront sensing and control for space telescopes utilizing active and adaptive optics

Kevin Derby, Kian Milani, Solvay Blomquist, Kyle Van Gorkom, Sebastiaan Haffert, Hyukmo Kang, Hill Tailor, Heejoo Choi, Christopher Mendillo, Jared Males, Daewook Kim, Ewan Douglas

Proceedings Volume 12677, 126770I (2023) https://doi.org/10.1117/12.2677663

KEYWORDS: Telescopes, Wavefronts, Wavefront errors, Wavefront sensors, Point spread functions, Coronagraphy, Signal to noise ratio, Error analysis, Integrated modeling, Wavefront compensation

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Proceedings Article | 4 October 2023 Presentation + Paper

Optimizing deflectometry to suppress ghost signal noise

Byeongjoon Jeong, Heejoo Choi, Sotero Ordones, Daewook Kim

Proceedings Volume 12677, 1267709 (2023) https://doi.org/10.1117/12.2677686

KEYWORDS: Interference (communication), Deflectometry, Reflection, Displays, Optical testing, Digital filtering, Tunable filters, Geometrical optics, Ray tracing, Image filtering

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Proceedings Article | 4 October 2023 Presentation + Paper

Compact three mirror anastigmat space telescope design using 6.5m monolithic primary mirror

Daewook Kim, Heejoo Choi, Ewan Douglas

Proceedings Volume 12677, 126770E (2023) https://doi.org/10.1117/12.2682180

KEYWORDS: Design and modelling, Telescopes, Space telescopes, Space mirrors, James Webb Space Telescope, Mirrors, Telescope design, Optical surfaces, Monochromatic aberrations, Stars

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Proceedings Article | 4 October 2023 Presentation + Paper

Analysis of active optics correction for a large honeycomb mirror

Solvay Blomquist, Hubert Martin, Hyukmo Kang, Rebecca Whitsitt, Kevin Derby, Heejoo Choi, Ewan Douglas, Daewook Kim

Proceedings Volume 12677, 126770H (2023) https://doi.org/10.1117/12.2677069

KEYWORDS: Wavefront errors, Actuators, Active optics, Mirrors, Mirror surfaces, Device simulation, Telescopes, Error analysis, Computer simulations, Surface finishing

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Proceedings Article | 4 October 2023 Presentation + Paper

Deflectometry for ophthalmic optics testing and the impact of test surface orientation

Rebecca Su, Heejoo Choi, Daewook Kim, James Schwiegerling

Proceedings Volume 12672, 1267206 (2023) https://doi.org/10.1117/12.2676217

KEYWORDS: Deflectometry, Cameras, Optical surfaces, Optical testing, Crystalline lens, Ophthalmic optics, Mirror surfaces, Displays

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Proceedings Article | 4 October 2023 Presentation + Paper

Advanced deflectometry methods for industrial application

Heejoo Choi, Hyukmo Kang, Yiyang Huang, Mina Yoo, Henry Quach, John Kam, Daewook Kim

Proceedings Volume 12684, 1268407 (2023) https://doi.org/10.1117/12.2678628

KEYWORDS: Deflectometry, Optical alignment, Image processing, Optical testing, Dark field illumination, Industrial applications

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Deflectometry is a versatile optical testing tool used in various fields, from astronomy to industrial applications, due to its non-null testing capability which facilitates precise measurement despite challenging optical surfaces and system layout constraints. In this manuscript, we present novel variational advancements to traditional deflectometry, towards universal functionality and system friendliness. Traditional dark-field illumination is an inspection technique that is sometimes used to detect particles on a specular surface. Problems arise in its repeatability, as an intensity-based measurement is vulnerably dependent on the testing conditions of time, limiting its ability to be used in automated fashion. The first advancement leverages phase algorithms commonly seen in deflectometry; by adding a secondary light source (normal to the surface) and modulating each source's intensity with a time-varying sinusoid. The phase-based information has a higher sensitivity to the light scattered from a defect producing a more robust computational image process method that is now insensitive to the environment. The second advancement is an alignment method to obtain lower-order shape. While deflectometry proves effective in measuring mid-to-high frequency surface shape, it faces challenges when assessing low-order shape measurements like power, astigmatism, and coma due to relative position and alignment error between the unit under test (UUT) and the deflectometry system. To avert the necessity of additional instruments like a coordinate measuring machine, laser trackers, or interferometers, we leveraged computational fiducials and sensitivity matrices to identify and address misalignments effectively. With enhanced capabilities and system-friendly features, our advanced deflectometry techniques provide powerful options in optical testing. By addressing the challenges in low-order shape measurements and incorporating dark field testing, our approaches extend the potential of deflectometry as a valuable tool in optical metrology across a broad spectrum of industries and scientific endeavors.

Proceedings Article | 27 September 2023 Presentation

Payload design and development of Aspera: the UV SmallSat mission for mapping warm-hot phase gas in nearby galaxy halos

Haeun Chung, Carlos Vargas, Erika Hamden, Thomas McMahon, Hannah Tanquary, Peter Behroozi, Ewan Douglas, Miriam Keppler, Nicole Melso, Simran Agarwal, Aafaque Khan, Jessica Li, Sumedha Uppnor, Jacob Chambers, Giulia Ghidoli, Gabe Noriega, Ryan Pecha, Ellie Wolcott, Fernando Coronado, Elijah Garcia, Daniel Truong, Naomi Yescas, Heejoo Choi, Tom Connors, Jason Corliss, Dave Hamara, Walter Harris, Karl Harshman, Daewook Kim, Corwynn Sauve, Bill Verts, Michael Ward, Dennis Zaritsky, Carl Hergenrother, John Kidd, Sanford Selznick, Oswald Siegmund, Simon Grocott, David Schiminovich, Keri Hoadley

Proceedings Volume 12678, 126780C (2023) https://doi.org/10.1117/12.2677212

KEYWORDS: Galactic astronomy, Design and modelling, Ultraviolet radiation, Spectrographs, Optical alignment, Computer generated holography, Ultraviolet telescopes, Ultraviolet detectors, UV-Vis spectroscopy, Tolerancing

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Proceedings Article | 8 March 2023 Presentation + Paper

AR and lidar applications enabled by beam and image steering by MEMS SLM

Yuzuru Takashima, Xianyue Deng, Chin-I Tang, Eunmo Kang, Heejoo Choi, Jeff Ching-Wen Chan, Jeff Chen, Brandon Friedman, Ted Liang-Tai Lee, Parker Liu, Gregory Michael Nero, Tianyao Zhang, Yexin Pei

Proceedings Volume 12445, 124450G (2023) https://doi.org/10.1117/12.2656192

KEYWORDS: LIDAR, Beam steering, Augmented reality, Digital micromirror devices, Microelectromechanical systems, Micromirrors, Image resolution, Spatial light modulators, Light sources and illumination, Autoregressive models

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SPIE Journal Paper | 2 December 2022

Plug-in cross-dispersing module for the Large Binocular Telescope’s infrared spectrograph LUCI

Hyukmo Kang, David Thompson, Al Conrad, James Wiese, Heejoo Choi, Vishnu Reddy, Daewook Kim

JATIS, Vol. 8, Issue 04, 045003, (December 2022) https://doi.org/10.1117/12.10.1117/1.JATIS.8.4.045003

KEYWORDS: Mirrors, Infrared telescopes, Telescopes, Near infrared, Spectrographs, Prisms, Infrared radiation, Equipment, Sensors, Spherical lenses

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SPIE Journal Paper | 25 November 2022 Open Access

Balloon-borne FIREBall-2 ultraviolet spectrograph stray light control based on nonsequential reverse modeling of on-sky data

Trenton Brendel, Aafaque Khan, Simran Agarwal, Heejoo Choi, Daewook Kim, Erika Hamden, Vincent Picouet, D. Christopher Martin, Bruno Milliard, David Schiminovich, Shouleh Nikzad, Jean Evrard, Nicolas Bray, Johan Montel, Keri Hoadley, Drew Miles, Gillian Kyne, Jessica Li, Zeren Lin, Haeun Chung, Philippe Balard, Patrick Blanchard, Marty Crabill, Charles-Antoine Chevrier, Alain Peus, Ignacio Cevallos-Aleman, Olivia Jones, Harrison Bradley, Naz Ipek Kerkeser, Matthew Werneken, Didier Vibert, Nicole Melso, David Valls-Gabaud

JATIS, Vol. 8, Issue 04, 048001, (November 2022) https://doi.org/10.1117/12.10.1117/1.JATIS.8.4.048001

KEYWORDS: Baffles, Stray light, Sensors, Spectrographs, Mirrors, Balloons, Ultraviolet radiation, Stray light control, Tongue, Light scattering

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Proceedings Article | 11 October 2022 Presentation

Polycalc optics for infrared optical imaging (Conference Presentation)

Kyung-Jo Kim, Kate Newcomer, Sasaan Showghi, Jay Liebowitz, Robert Norwood, Heejoo Choi

Proceedings Volume 12219, 122190J (2022) https://doi.org/10.1117/12.2634177

KEYWORDS: Thermography, Infrared imaging, Infrared radiation, Optical imaging, Packaging, Infrared sensors, Wafer-level optics, Resistance, Polymers, Optical components

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Proceedings Article | 3 October 2022 Presentation + Paper

Influence of lens and perspective distortion on optical surface metrology instrumentation

Henry Quach, Joel Berkson, Hyukmo Kang, Heejoo Choi, Daewook Kim

Proceedings Volume 12221, 122210M (2022) https://doi.org/10.1117/12.2633090

KEYWORDS: Distortion, Metrology, Imaging systems, Image processing, Cameras, Calibration

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Proceedings Article | 3 October 2022 Presentation + Paper

Initial testing of a MODE lens telescope

Youngsik Kim, Marcos Esparza, Zichan Wang, Nicholas Brar, Yingying Zhang, Daewook Kim, Heejoo Choi, Daniel Apai, Chuck Fellows, Allen Yi, Yuxin Cai, Geonhee Kim, Hwanjin Choi, Woojong Yeo, Tom Milster

Proceedings Volume 12221, 122210J (2022) https://doi.org/10.1117/12.2633443

KEYWORDS: Telescopes, Diffraction, Lens design, Spherical lenses, Optical instrument design, Optical fabrication, Glasses

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Proceedings Article | 3 October 2022 Presentation + Paper

Autonomous closed-loop control for multi-segmented optic aligning and assembly

Heejoo Choi, Marcos A. Esparza, Ryan Luu, Tom Milster, Daniel Apai, Daewook Kim

Proceedings Volume 12221, 122210H (2022) https://doi.org/10.1117/12.2633760

KEYWORDS: Metrology, Optical alignment, Optics manufacturing, Telescopes, Segmented mirrors, Deflectometry, Automatic alignment

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Proceedings Article | 3 October 2022 Presentation + Paper

Nautilus Space Observatory: a very large aperture space telescope constellation enabled by scalable optical manufacturing technologies

Dániel Apai, Tom Milster, Daewook Kim, Youngsik Kim, Glenn Schneider, Benjamin Rackham, Jonathan Arenberg, Heejoo Choi, Marcos Esparza, Zichan Wang, Yingying Zhang, Alex Bixel

Proceedings Volume 12221, 122210C (2022) https://doi.org/10.1117/12.2633184

KEYWORDS: Diffractive optical elements, Astrobiology, Telescopes, Space observatories, Planets, Space telescopes, James Webb Space Telescope, Space operations, Stars, Satellites, Optical fabrication

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Proceedings Article | 3 October 2022 Presentation + Paper

Progress towards alignment of Multi-Order Diffractive Engineered (MODE) lens segments using the Kinematically-Engaged Yoke System (KEYS) for optical performance testing

Marcos Esparza, Ryan Luu, Heejoo Choi, Tom Milster, Daniel Apai, Daewook Kim

Proceedings Volume 12221, 122210I (2022) https://doi.org/10.1117/12.2633685

KEYWORDS: Optical alignment, Telescopes, Optical testing, 3D modeling, Observatories, Magnetism, Glasses, Fresnel lenses, Tolerancing, Space observatories

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Proceedings Article | 3 October 2022 Presentation + Paper

Stray light analysis and testing of a MODE lens telescope

Youngsik Kim, Marcos Esparza, Zichan Wang, Nicholas Brar, Heejoo Choi, Daewook Kim, Daniel Apai, Tom Milster

Proceedings Volume 12221, 122210F (2022) https://doi.org/10.1117/12.2635495

KEYWORDS: Stray light, Telescopes, Stray light analysis, Ray tracing, Lens design, Cameras, Receivers, Optical testing, Optical fabrication

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Proceedings Article | 3 October 2022 Open Access

The practical optics workshop: educating the optical engineers of tomorrow

Jaren N. Ashcraft, Trenton Brendel, Simran Agarwal, Joel Berkson, Alexander Hedglen, Hyukmo Kang, Yanqi Zhang, Heejoo Choi, Daewook Kim

Proceedings Volume 12213, 122130H (2022) https://doi.org/10.1117/12.2632801

KEYWORDS: Optics education, Education and training, Optical design, Optical engineering, Optical design software

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Proceedings Article | 29 August 2022 Presentation + Paper

Curved primary aperture segmentation enabling a robust quasi-Airy pattern point spread function

Kevin Z. Derby, James B. Breckinridge, James E. Harvey, Tony Hull, Charles F. Lillie, Jaren N. Ashcraft, Heejoo Choi, Ewan S. Douglas, Daewook Kim

Proceedings Volume 12188, 121880N (2022) https://doi.org/10.1117/12.2628819

KEYWORDS: Point spread functions, Coronagraphy, Diffraction, Wavefronts, Telescopes, Mirrors, Wave propagation, Performance modeling, Observatories

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Proceedings Article | 29 August 2022 Poster + Paper

Balloon-borne FIREBall-2 UV spectrograph stray light control based on non-sequential reverse modeling of on-sky data

Trenton Brendel, Aafaque Khan, Simran Agarwal, Heejoo Choi, Daewook Kim, Erika Hamden

Proceedings Volume 12182, 121823L (2022) https://doi.org/10.1117/12.2631704

KEYWORDS: Stray light, Sensors, Mirrors, Spectrographs, Light scattering, Ultraviolet radiation, Scattering

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Proceedings Article | 29 August 2022 Presentation + Paper

The GMT telescope metrology system design

Breann Sitarski, Andrew Rakich, Hugo Chiquito, Wylie Rosenthal, Antonin Bouchez, William Schoenell, Bo Xin, Priscila Pires, Joel Nissen, P. Schurter, Richard Demers, Peter Thompson, Brian McLeod, Bijan Nemati, Glenn Brossus, Brian Walls, Heejoo Choi, Guillermo Gonzalez, David Nemati

Proceedings Volume 12182, 1218207 (2022) https://doi.org/10.1117/12.2630598

KEYWORDS: Mirrors, Retroreflectors, Sensors, Telescopes, Error analysis, Collimators, Prototyping, Metrology, Laser metrology

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Proceedings Article | 27 August 2022 Presentation + Paper

Orbiting astronomical satellite for investigating stellar systems (OASIS): a paradigm shift in realizing large space telescopes

Siddhartha Sirsi, Christopher Walker, Jonathan Arenberg, Yuzuru Takashima, Daewook Kim, Heejoo Choi, Arthur Palisoc, Henry Quach, Marcos Esparza, Kevin Derby, Luke Mayer, Tianyao Zhang, Aman Chandra, Anthony Stark

Proceedings Volume 12180, 121801Q (2022) https://doi.org/10.1117/12.2629100

KEYWORDS: Space telescopes, Receivers, Astronomy, Optical design, Satellites, Mirrors, Cryogenics, Space operations, Metrology, LIDAR

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Proceedings Article | 27 August 2022 Poster + Paper

Tolerance analysis of a self-coherent camera for wavefront sensing and dark hole maintenance

Kevin Derby, Sebastiaan Haffert, Jaren Ashcraft, Kian Milani, Heejoo Choi, Young-Sik Kim, Laird Close, Christopher Mendillo, Supriya Chakrabarti, Gregory Allan, Leonid Pogorelyuk, Kerri Cahoy, Mamadou N'Diaye, Daewook Kim, Jared Males, Ewan Douglas

Proceedings Volume 12180, 1218069 (2022) https://doi.org/10.1117/12.2629578

KEYWORDS: Wavefronts, Sensors, Coronagraphy, Wavefront sensors, Tolerancing, Cameras, Stars, Telescopes, Photodetectors, Error analysis

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Proceedings Article | 27 August 2022 Poster + Paper

The space coronagraph optical bench (SCoOB): 2. Wavefront sensing and control in a vacuum-compatible coronagraph testbed for spaceborne high-contrast imaging technology

Kyle Van Gorkom, Ewan Douglas, Jaren Ashcraft, Sebastiaan Haffert, Daewook Kim, Heejoo Choi, Ramya Anche, Jared Males, Kian Milani, Kevin Derby, Lori Harrison, Olivier Durney

Proceedings Volume 12180, 121805M (2022) https://doi.org/10.1117/12.2630704

KEYWORDS: Coronagraphy, Wavefronts, Wavefront sensors, Actuators, Optical benches, Astronomical imaging, Cameras, Point spread functions, Imaging technologies, Light scattering

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Proceedings Article | 27 August 2022 Poster + Paper

The space coronagraph optical bench (SCoOB): 1. Design and assembly of a vacuum-compatible coronagraph testbed for spaceborne high-contrast imaging technology

Jaren Ashcraft, Heejoo Choi, Ewan Douglas, Kevin Derby, Kyle Van Gorkom, Daewook Kim, Ramya Anche, Alex Carter, Olivier Durney, Sebastiaan Haffert, Lori Harrison, Maggie Kautz, Jennifer Lumbres, Jared Males, Kian Milani, Oscar Montoya, George Smith

Proceedings Volume 12180, 121805L (2022) https://doi.org/10.1117/12.2628855

KEYWORDS: Coronagraphy, Wavefronts, Mirrors, Interferometers, Wavefront sensors, Point spread functions, Optical benches, Cameras, Astronomical imaging

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SPIE Journal Paper | 16 August 2022 Open Access

Optical design of the Orbiting Astronomical Satellite for Investigating Stellar Systems

Siddhartha Sirsi, Yuzuru Takashima, Arthur Palisoc, Heejoo Choi, Jonathan Arenberg, Daewook Kim, Christopher Walker

JATIS, Vol. 8, Issue 03, 034002, (August 2022) https://doi.org/10.1117/12.10.1117/1.JATIS.8.3.034002

KEYWORDS: Mirrors, Optical design, Astronomy, Satellites, Reflectors, Receivers, Telescopes, Monochromatic aberrations, Space telescopes, Wavefronts

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Proceedings Article | 2 March 2022 Presentation + Paper

Large etendue solid-state-lidar with MEMS-resonant mirror assisted diffractive beam steering by digital micro mirror device

Eunmo Kang, Heejoo Choi, Brandon Hellman, Joshua Rodriguez, Braden Smith, Xianyue Deng, Parker Liu, Ted Lian-Tai Lee, Erik Evans, Yifan Hong, Jiafan Guan, Chuan Luo, Yuzuru Takashima

Proceedings Volume 12014, 1201407 (2022) https://doi.org/10.1117/12.2608501

KEYWORDS: Digital micromirror devices, Mirrors, Beam steering, Microelectromechanical systems, LIDAR, Diffraction, Micromirrors, Image restoration, Transmitters, Receivers

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Proceedings Article | 1 September 2021 Open Access

Mid-to-high frequency characterization of inflatable membrane optics

Heejoo Choi, Art Palisoc, Amarjiit Vikkas, Marcos Esparza, Joel Berkson, Yuzuru Takashima, Daewook Kim, Christopher Walker

Proceedings Volume 11820, 118200V (2021) https://doi.org/10.1117/12.2594412

KEYWORDS: Deflectometry, Optical testing, Optical fabrication, Interferometers, Spatial frequencies, Metrology, Mirrors, Telescopes

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Proceedings Article | 24 August 2021 Open Access

All reflective THz telescope design with an inflatable primary antenna for Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) mission

Yuzuru Takashima, Siddhartha Sirsi, Heejoo Choi, Jonathan Arenberg, Daewook Kim, Christopher Walker

Proceedings Volume 11820, 118200P (2021) https://doi.org/10.1117/12.2594610

KEYWORDS: Antennas, Mirrors, Scanners, Reflectivity, Optical design, Terahertz radiation, Sensors, Geometrical optics, Astronomy, Aluminum

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Proceedings Article | 24 August 2021 Open Access

Stressed deformable reflector design and pneumatic membrane antenna for cryogenic thermal vacuum chamber testing

Marcos Esparza, Heejoo Choi, Hyukmo Kang, Christian d'Aubigny, Amarjiit Pandde, Henry Quach, Aman Chandra, Karlene Karrfalt, Yuzuru Takashima, Art Palisoc, Jonathan Arenberg, Kristy Gogick Marshall, Christopher Glynn, Sean Godinez, Marcos Tafoya, Brandon Chalifoux, Christopher Walker, Daewook Kim

Proceedings Volume 11820, 118200R (2021) https://doi.org/10.1117/12.2594403

KEYWORDS: Actuators, Reflectors, Computer aided design, Antennas, Prototyping, Polonium, Reflector design, Aluminum, Wavefronts, Solid modeling

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Proceedings Article | 24 August 2021 Open Access

Analytical and finite element analysis tool for nonlinear membrane antenna modeling for astronomical applications

Arthur Palisoc, Gerard Pardoen, Yuzuru Takashima, Aman Chandra, Siddharta Sirsi, Heejoo Choi, Daewook Kim, Henry Quach, Jonathan Arenberg, Christopher Walker

Proceedings Volume 11820, 118200U (2021) https://doi.org/10.1117/12.2594050

KEYWORDS: Reflectors, Finite element methods, James Webb Space Telescope, Telescopes, Mirrors, Antennas, Inverse problems

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The uninflated shape configurations of parabolic and spherical membrane mirrors were calculated by solving the inverse problem, i.e., given the design inflation pressure, the membrane material and geometric properties, what must be the initial uninflated shape such that on inflation to the design pressure, the exact desired surface of revolution is obtained. The resulting first order nonlinear differential equation was numerically integrated using the boundary conditions. The initial uninflated shape was then subjected to a forward transformation using FAIM, a proprietary geometric nonlinear membrane finite element code. FAIM has been validated against exact analytical solutions for both small and extremely large deformations that are up to eight orders of magnitude larger compared with the starting undeflected shape. Simulations reveal that to fabricate a very accurate and precise inflated membrane mirror relative to the design parameters, one must not only accurately measure and input the moduli in both meridional and hoop directions but an accurately measured Poisson’s ratio as well. The code was used to guide the membrane mirror design. For very small aperture diameters, the initial uninflated shape may be fabricated by thermo-forming the membrane. For aperture diameters exceeding one meter however, the membrane mirror is built with discrete gores that are joined together with tapes at the seams. This provided the impetus to write a companion computer code FLATE, to calculate the gore shapes using a slight modification of the solution to the inverse transformation equation to account for the presence of the seam tapes. After the gores were determined, the resulting final inflated shape was calculated and verified using FAIM. Sensitivity analyses can now be carried out to determine the resulting surface shape as a function of the different sources of error: gore width, gore length, perimeter attachment uncertainties, thermal effects, variation of material properties over the membrane continuum and inflation pressure changes. The code has been shown to be more robust than equivalent commercial analytical packages in so far as membrane, cable and space-frame element combinations are concerned. In particular, the analytical and finite element codes were used in the preliminary assessment of a membrane optic for the OASIS Mission (Orbiting Astronomical Satellite for Investigating Stellar Systems) [1]. The OASIS is a 20-meter class space observatory operating at high spectral resolution in the terahertz frequencies. Over its nominal 2-year mission it will probe conditions and search for biogenic molecules on hundreds of protoplanetary disks and other solar system objects.

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Proceedings Article | 24 August 2021 Open Access

Deflectometry-based thermal vacuum testing for a pneumatic terahertz antenna

Henry Quach, Marcos Esparza, Hyukmo Kang, Aman Chandra, Heejoo Choi, Joel Berkson, Karlene Karrfalt, Siddhartha Sirsi, Yuzuru Takashima, Art Palisoc, Jonathan Arenberg, Kristy Gogick Marshall, Christopher Glynn, Sean Godinez, Marcos Tafoya, Christopher Walker, Christian Drouet d'Aubigny, Daewook Kim

Proceedings Volume 11820, 118200W (2021) https://doi.org/10.1117/12.2594902

KEYWORDS: Deflectometry, Calibration, Cameras, Antennas, Metrology

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Proceedings Article | 24 August 2021 Presentation + Paper

Cosmic evolution through UV surveys (CETUS): point spread function analysis of three mirror anastigmat telescope

Jaren Ashcraft, Heejoo Choi, Sara Heap, Robert Woodruff, Dae Wook Kim

Proceedings Volume 11820, 118200H (2021) https://doi.org/10.1117/12.2598879

KEYWORDS: Mirrors, Point spread functions, Diffraction, Ultraviolet radiation, Telescopes, Hubble Space Telescope, Surface finishing, Observatories, Ultraviolet telescopes, Monochromatic aberrations

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Proceedings Article | 20 August 2021 Presentation + Paper

Aspera: the UV SmallSat telescope to detect and map the warm-hot gas phase in nearby galaxy halos

Haeun Chung, Carlos Vargas, Erika Hamden, Tom McMahon, Kerry Gonzales, Aafaque Khan, Simran Agarwal, Hop Bailey, Peter Behroozi, Trenton Brendel, Heejoo Choi, Tom Connors, Lauren Corlies, Jason Corliss, Ralf-Jürgen Dettmar, David Dolana, Ewan Douglas, John Guzman, Dave Hamara, Walt Harris, Karl Harshman, Carl Hergenrother, Keri Hoadley, John Kidd, Daewook Kim, Jessica Li, Manny Montoya, Corwynn Sauve, David Schiminovich, Sanford Selznick, Oswald Siegmund, Michael Ward, Ellie Wolcott, Dennis Zaritsky

Proceedings Volume 11819, 1181903 (2021) https://doi.org/10.1117/12.2593001

KEYWORDS: Galactic astronomy, Spectrographs, Microchannel plates, Telescopes, Spectral resolution, Ultraviolet radiation, Target detection, Signal detection, Mirrors

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SPIE Journal Paper | 12 March 2021

Long-slit cross-dispersion spectroscopy for Hyperion UV space telescope

Heejoo Choi, Isaac Trumper, Yi-Ting Feng, Hyukmo Kang, Joel Berkson, Haeun Chung, Erika Hamden, Dae Wook Kim

JATIS, Vol. 7, Issue 01, 014006, (March 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.1.014006

KEYWORDS: Spectroscopy, Sensors, Ultraviolet radiation, Space telescopes, Spectral resolution, Diffraction gratings, Optical design, Freeform optics, Diffraction, Mirrors

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Proceedings Article | 5 March 2021 Presentation + Paper

Stability of diffractive beam steering by a digital micromirror device

Jiafan Guan, Erik Evans, Heejoo Choi, Yuzuru Takashima

Proceedings Volume 11698, 116980I (2021) https://doi.org/10.1117/12.2582899

KEYWORDS: Beam steering, Digital micromirror devices, LIDAR, Sensors, Micromirrors, Pulsed laser operation, Diffraction, Signal detection, Oscilloscopes, Mirrors

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Proceedings Article | 15 January 2021 Paper

Optical technology for future telescopes

Dae Wook Kim, Marcos Esparza, Henry Quach, Stephanie Rodriguez, Hyukmo Kang, Yi-Ting Feng, Heejoo Choi

Proceedings Volume 11761, 1176103 (2021) https://doi.org/10.1117/12.2586867

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Proceedings Article | 13 December 2020 Open Access

Design of the vacuum high contrast imaging testbed for CDEEP, the Coronagraphic Debris and Exoplanet Exploring Pioneer

Erin Maier, Ewan Douglas, Dae Wook Kim, Kate Su, Jaren Ashcraft, James Breckinridge, Heejoo Choi, Elodie Choquet, Thomas Connors, Olivier Durney, Kerry Gonzales, Charlotte Guthery, Christian Haughwout, James Heath, Justin Hyatt, Jennifer Lumbres, Jared Males, Elisabeth Matthews, Kian Milani, Oscar Montoya, Mamadou N'Diaye, Jamison Noenickx, Leonid Pogorelyuk, Garreth Ruane, Glenn Schneider, George Smith, Christopher Stark

Proceedings Volume 11443, 114431Y (2020) https://doi.org/10.1117/12.2560878

KEYWORDS: Coronagraphy, Exoplanets, Deformable mirrors, Microelectromechanical systems, Prototyping, Light scattering, Visible radiation, Wavefronts, Rockets, Telescopes

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Proceedings Article | 13 December 2020 Presentation + Paper

A laser-truss based optical alignment system on LBT

Andrew Rakich, Heejoo Choi, Christian Veillet, John Hill, Matthieu Bec, Yang Zhang, Trenton Brendel, Breann Sitarski, Michael Gardiner, Dae Wook Kim, Stephanie Rodriguez

Proceedings Volume 11445, 114450R (2020) https://doi.org/10.1117/12.2558013

KEYWORDS: Mirrors, Telescopes, Prototyping, Laser systems engineering, Optical alignment, Metrology, Laser metrology, Cameras, Kinematics, Collimators

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Proceedings Article | 5 November 2020 Open Access

Topological pupil segmentation and point spread function analysis for large aperture imaging systems

Yi-Ting Feng, Jaren Nicholas Ashcraft, James Breckinridge, James Harvey, Ewan Douglas, Heejoo Choi, Charles Lillie, Tony Hull, Dae Wook Kim

Proceedings Volume 11568, 115680I (2020) https://doi.org/10.1117/12.2575809

KEYWORDS: Telescopes, James Webb Space Telescope, Point spread functions, Exoplanets, Mirrors, Stars, Diffraction, Imaging systems, Image segmentation, Optical instrument design

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Proceedings Article | 20 August 2020 Presentation + Paper

Computational alignment of on-machine deflectometry

Hyukmo Kang, Henry Quach, Heejoo Choi, Greg Smith, Dae Wook Kim

Proceedings Volume 11487, 114870O (2020) https://doi.org/10.1117/12.2576955

KEYWORDS: Deflectometry, Computer simulations, Sensors, Calibration, Cameras, Optical alignment, Measurement devices, Ray tracing

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Proceedings Article | 20 August 2020 Presentation + Paper

Hyperion: Far-UV cross dispersion spectroscope design

Heejoo Choi, Isaac Trumper, Yi-Ting Feng, Hyukmo Kang, Erika Hamden, Dae Wook Kim

Proceedings Volume 11487, 114870W (2020) https://doi.org/10.1117/12.2570489

KEYWORDS: Spectroscopy, Optical design, Spectral resolution, Diffraction gratings, Diffraction, Mirrors, Freeform optics, Telescopes

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Proceedings Article | 20 August 2020 Presentation + Paper

Non-planar illumination sources for deflectometry

Henry Quach, Hyukmo Kang, Heejoo Choi, Dae Wook Kim

Proceedings Volume 11487, 114870L (2020) https://doi.org/10.1117/12.2568168

KEYWORDS: Deflectometry, Optics manufacturing, Prototyping, Light sources

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Proceedings Article | 20 August 2020 Presentation + Paper

Full-aperture optical metrology for inflatable membrane mirrors

Henry Quach, Joel Berkson, Siddhartha Sirsi, Heejoo Choi, Ruben Dominguez, Brian Duffy, David Lesser, Yuzuru Takashima, Art Palisoc, Christopher Walker, Dae Wook Kim

Proceedings Volume 11487, 114870N (2020) https://doi.org/10.1117/12.2569750

KEYWORDS: Deflectometry, Metrology, Reflectors, Photogrammetry, Telescopes

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Proceedings Article | 20 August 2020 Presentation + Paper

Implementation of a laser-truss based telescope metrology system at the Large Binocular Telescope

Stephanie Rodriguez, Andrew Rakich, John Hill, Olga Kuhn, Trenton Brendel, Christian Veillet, Dae Wook Kim, Heejoo Choi

Proceedings Volume 11487, 114870E (2020) https://doi.org/10.1117/12.2576438

KEYWORDS: Telescopes, Kinematics, Metrology, Collimation, Image quality, Control systems

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Proceedings Article | 20 August 2020 Presentation + Paper

In-process metrology for segmented optics UV curing control

Heejoo Choi, Marcos Esparza, Ariel Lamdan, Yi-Ting Feng, Tom Milster, Daniel Apai, Dae Wook Kim

Proceedings Volume 11487, 114870M (2020) https://doi.org/10.1117/12.2569310

KEYWORDS: Metrology, Optical fabrication, Optical alignment, Telescopes, Cameras, Tolerancing

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Proceedings Article | 20 August 2020 Presentation + Paper

Alignment of Multi-Order Diffractive Engineered (MODE) lens segments using the Kinematically-Engaged Yoke System

Marcos Esparza, Heejoo Choi, Dae Wook Kim

Proceedings Volume 11487, 114870V (2020) https://doi.org/10.1117/12.2569442

KEYWORDS: Optical alignment, Tolerancing, Deflectometry, Telescopes, Observatories, Image segmentation, 3D modeling, Mirrors, Interferometers

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Proceedings Article | 7 April 2020 Paper

Reconfigurable dynamic optical system design, test, and data analysis

Dae Wook Kim, Maham Aftab, Isaac Trumper, Logan Graves, Henry Quach, Hyukmo Kang, Hyemin Yoo, Andrew Lowman, Greg Smith, Matt Dubin, Chang-Jin Oh, Justin Hyatt, Christian Davila-Peralta, Heejoo Choi

Proceedings Volume 11352, 1135202 (2020) https://doi.org/10.1117/12.2555650

KEYWORDS: Deflectometry, Freeform optics, Optical testing, Optical design, Optics manufacturing, Infrared radiation, Metrology, Data analysis, Mirrors

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Proceedings Article | 28 February 2020 Presentation + Paper

Angular and spatial light modulation by single digital micromirror device for beam and pattern steering

Brandon Hellman, Joshua Rodriguez, Chuan Luo, Heejoo Choi, Yuzuru Takashima

Proceedings Volume 11294, 112940C (2020) https://doi.org/10.1117/12.2546355

KEYWORDS: Digital micromirror devices, Wavefronts, Diffraction, Micromirrors, Beam steering, LIDAR, Mirrors, Spatial light modulators, Modulation

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Proceedings Article | 12 September 2019 Presentation

High-speed LiDAR by multi-order laser beam steering with digital micromirror device (Conference Presentation)

Joshua Rodriguez, Braden Smith, Brandon Hellman, Heejoo Choi, Guanghao Chen, Young Sik Kim, Dae Wook Kim, Yuzuru Takashima

Proceedings Volume 11125, 111250I (2019) https://doi.org/10.1117/12.2529029

KEYWORDS: LIDAR, Digital micromirror devices, Beam steering, Laser sources, Semiconductor lasers, Laser applications, Optical components, Microscopy, Microelectromechanical systems, Mirrors

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Proceedings Article | 3 September 2019 Presentation + Paper

Robust and objective automatic optical surface inspection using modulated dark field phasing illumination

Heejoo Choi, John Kam, Joel Berkson, Logan Graves, Huang Lei, Dae Wook Kim

Proceedings Volume 11102, 1110207 (2019) https://doi.org/10.1117/12.2529869

KEYWORDS: Particles, Inspection, Image processing, Modulation, Optical inspection, Data processing

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Proceedings Article | 13 May 2019 Presentation

Compact snapshot freefrom null testing with adaptive optics (Conference Presentation)

Xiaobo Tian, Heejoo Choi, Alexander Sohn, Yu Zhang, Oliver Joshua Spires, Dae Wook Kim, Rongguang Liang

Proceedings Volume 10991, 109910Q (2019) https://doi.org/10.1117/12.2518789

KEYWORDS: Deformable mirrors, Optical testing, Adaptive optics, Algorithm development, Wavefronts, Interferometry, Stochastic processes, Phase measurement, Deflectometry

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SPIE Journal Paper | 17 April 2019

Pseudorandom orbiting stroke for freeform optics postprocessing

Xiangyu Guo, Yong Shu, Geon-Hee Kim, Michael Palmer, Heejoo Choi, Dae Wook Kim

OE, Vol. 58, Issue 09, 092608, (April 2019) https://doi.org/10.1117/12.10.1117/1.OE.58.9.092608

KEYWORDS: Freeform optics, Single point diamond turning, Polymethylmethacrylate, Spatial frequencies, Radium, Polishing, Surface finishing, Optics manufacturing, Surface roughness, Photovoltaics

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SPIE Journal Paper | 26 March 2019

Modulated dark-field phasing detection for automatic optical inspection

Heejoo Choi, John Mineo Kam, Joel David Berkson, Logan Rodriguez Graves, Dae Wook Kim

OE, Vol. 58, Issue 09, 092603, (March 2019) https://doi.org/10.1117/12.10.1117/1.OE.58.9.092603

KEYWORDS: Particles, Modulation, Optical inspection, Sensors, Light emitting diodes, Signal to noise ratio, Inspection, Light sources, Optical engineering, Data processing

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Proceedings Article | 14 September 2018 Presentation + Paper

Model-free optical surface reconstruction from deflectometry data

L. Graves, H. Choi, W. Zhao, C. J. Oh, P. Su, T. Su, D. W. Kim

Proceedings Volume 10742, 107420Y (2018) https://doi.org/10.1117/12.2320745

KEYWORDS: Deflectometry, Cameras, Data modeling, Interferometry, Freeform optics, Monochromatic aberrations, Systems modeling, Metrology, Computer generated holography, Ray tracing

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Proceedings Article | 5 September 2017 Presentation + Paper

Instantaneous phase mapping deflectometry for dynamic deformable mirror characterization

Isaac Trumper, Heejoo Choi

Proceedings Volume 10401, 104010S (2017) https://doi.org/10.1117/12.2272188

KEYWORDS: Deflectometry, Deformable mirrors, Metrology, Motion measurement, Phase shifting, High dynamic range imaging, Dynamical systems, Interferometers

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Proceedings Article | 22 August 2017 Presentation + Paper

Simultaneous angular alignment of segmented mirrors using sinusoidal pattern analysis

Heejoo Choi, Isaac Trumper, Matthew Dubin, Wenchuan Zhao, Dae Wook Kim

Proceedings Volume 10377, 103770G (2017) https://doi.org/10.1117/12.2275197

KEYWORDS: Mirrors, Segmented mirrors, Optical alignment, Telescopes, Reflection

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Proceedings Article | 15 June 2017 Paper

Dynamic metrology and data processing for precision freeform optics fabrication and testing

Maham Aftab, Isaac Trumper, Lei Huang, Heejoo Choi, Wenchuan Zhao, Logan Graves, Chang Jin Oh, Dae Wook Kim

Proceedings Volume 10326, 103260H (2017) https://doi.org/10.1117/12.2272353

KEYWORDS: Freeform optics, Deformable mirrors, Cameras, Interferometers, Metrology, Data processing, Deflectometry, Optical testing, Interferometry, Phase shifting, Optical components, Precision optics, Optical fabrication, Optical metrology

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Proceedings Article | 18 August 2014 Paper

Simultaneous determination of thickness and refractive indices of birefringent wafer by simple transmission measurement

Hee Joo Choi, Jun Yeol Ryu, Myoungsik Cha

Proceedings Volume 9203, 920309 (2014) https://doi.org/10.1117/12.2063280

KEYWORDS: Semiconducting wafers, Refractive index, Crystals, Collimation, Polarization, Refraction, Nonlinear crystals, Interferometry, Transmittance, Optical testing

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Proceedings Article | 20 February 2014 Paper

Estimation of random duty-cycle error in periodically poled lithium niobate by simple diffraction experiment

Prashant Povel Dwivedi, Hee Joo Choi, Byoung Joo Kim, Myoungsik Cha

Proceedings Volume 8964, 896418 (2014) https://doi.org/10.1117/12.2039246

KEYWORDS: Diffraction, Lithium niobate, Second-harmonic generation, Diffraction gratings, Error analysis, Tunable lasers, Ions, Neodymium, Frequency conversion, Crystals

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Proceedings Article | 3 August 2010 Paper

Determination of refractive index of transparent plate by Fabry-Perot fringe analysis

Hee Joo Choi, Hwan Hong Lim, Han Seb Moon, Tae Bong Eom, Jung Ju, Myoungsik Cha

Proceedings Volume 7790, 77900Z (2010) https://doi.org/10.1117/12.862363

KEYWORDS: Refractive index, Fringe analysis, Refraction, Fabry–Perot interferometers, Interferometry, Silica, Solids, Helium neon lasers, Collimation, Wave plates

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