TY - GEN
T1 - Brightness checkerboard lattice method for the calibration of the coaxial reverse Hartmann test
AU - Li, Xinji
AU - Hui, Mei
AU - Li, Ning
AU - Hu, Shinan
AU - Liu, Ming
AU - Kong, Lingqin
AU - Dong, Liquan
AU - Zhao, Yuejin
N1 - Publisher Copyright:
© 2018 Copyright SPIE.
PY - 2018
Y1 - 2018
N2 - The coaxial reverse Hartmann test (RHT) is widely used in the measurement of large aspheric surfaces as an auxiliary method for interference measurement, because of its large dynamic range, highly flexible test with low frequency of surface errors, and low cost. And the accuracy of the coaxial RHT depends on the calibration. However, the calibration process remains inefficient, and the signal-to-noise ratio limits the accuracy of the calibration. In this paper, brightness checkerboard lattices were used to replace the traditional dot matrix. The brightness checkerboard method can reduce the number of dot matrix projections in the calibration process, thus improving efficiency. An LCD screen displayed a brightness checkerboard lattice, in which the brighter checkerboard and the darker checkerboard alternately arranged. Based on the image on the detector, the relationship between the rays at certain angles and the photosensitive positions of the detector coordinates can be obtained. And a differential de-noising method can effectively reduce the impact of noise on the measurement results. Simulation and experimentation proved the feasibility of the method. Theoretical analysis and experimental results show that the efficiency of the brightness checkerboard lattices is about four times that of the traditional dot matrix, and the signal-to-noise ratio of the calibration is significantly improved.
AB - The coaxial reverse Hartmann test (RHT) is widely used in the measurement of large aspheric surfaces as an auxiliary method for interference measurement, because of its large dynamic range, highly flexible test with low frequency of surface errors, and low cost. And the accuracy of the coaxial RHT depends on the calibration. However, the calibration process remains inefficient, and the signal-to-noise ratio limits the accuracy of the calibration. In this paper, brightness checkerboard lattices were used to replace the traditional dot matrix. The brightness checkerboard method can reduce the number of dot matrix projections in the calibration process, thus improving efficiency. An LCD screen displayed a brightness checkerboard lattice, in which the brighter checkerboard and the darker checkerboard alternately arranged. Based on the image on the detector, the relationship between the rays at certain angles and the photosensitive positions of the detector coordinates can be obtained. And a differential de-noising method can effectively reduce the impact of noise on the measurement results. Simulation and experimentation proved the feasibility of the method. Theoretical analysis and experimental results show that the efficiency of the brightness checkerboard lattices is about four times that of the traditional dot matrix, and the signal-to-noise ratio of the calibration is significantly improved.
KW - Brightness checkerboard lattice
KW - Calibration
KW - Differential de-noising
KW - Reverse Hartmann test
UR - http://www.scopus.com/inward/record.url?scp=85049941314&partnerID=8YFLogxK
U2 - 10.1117/12.2288068
DO - 10.1117/12.2288068
M3 - Conference contribution
AN - SCOPUS:85049941314
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - 2017 International Conference on Optical Instruments and Technology
A2 - Xu, Kexin
A2 - Xiao, Hai
A2 - Zhu, Jigui
A2 - Tam, Hwa-Yaw
PB - SPIE
T2 - 2017 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Systems
Y2 - 28 October 2017 through 30 October 2017
ER -