TY - GEN
T1 - Advanced deflectometry methods for industrial application
AU - Choi, Heejoo
AU - Kang, Hyukmo
AU - Huang, Yiyang
AU - Yoo, Mina
AU - Quach, Henry
AU - Kam, John
AU - Kim, Daewook
N1 - Publisher Copyright:
© 2023 SPIE · 0277-786X ·
PY - 2023
Y1 - 2023
N2 - 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.
AB - 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.
KW - alignment
KW - dark field illumination
KW - deflectometry
KW - optical testing
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U2 - 10.1117/12.2678628
DO - 10.1117/12.2678628
M3 - Conference contribution
AN - SCOPUS:85178258712
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - ODS 2023
A2 - Katayama, Ryuichi
A2 - Takashima, Yuzuru
PB - SPIE
T2 - Industrial Optical Devices and Systems, ODS 2023
Y2 - 21 August 2023
ER -