Modeling and test of an absolute four-degree-of-freedom (DOF) grating encoder

Shengtong Wang; Junhao Zhu; Ningning Shi; Linbin Luo; Yanxiang Wen; Xinghui Li

doi:10.1117/12.2643904

19 December 2022 Modeling and test of an absolute four-degree-of-freedom (DOF) grating encoder

Shengtong Wang, Junhao Zhu, Ningning Shi, Linbin Luo, Yanxiang Wen, Xinghui Li

Proceedings Volume 12319, Optical Metrology and Inspection for Industrial Applications IX; 123190I (2022) https://doi.org/10.1117/12.2643904
Event: SPIE/COS Photonics Asia, 2022, Online Only

Abstract

For solving the problem of sub-mirror installation and posture monitoring and compensation, an absolute four-degree-of-freedom (DOF) grating encoder that is able to monitor four degrees of freedom's absolute position and pose in the θx, θy, θz, and z-direction is proposed. In this grating encoder, a grating reflector and three quadrant photodetectors (QPD) are employed and an optical path is configured based on the laser autocollimation principle. A model for the solution of the four-DOF motions from outputs of the three QPDs is established. A calibration method for the identification of the relationships between the absolute positions and QPDs outputs is proposed. A prototype four-DOF grating encoder is constructed for verification of this proposal. Test results demonstrated that the method proposed in this research can achieve absolute position distinguishing with a sub-arcsecond and sub-micrometer accuracy in rotation angles and z-direction, respectively.

Conference Presentation

Citation Download Citation

Shengtong Wang, Junhao Zhu, Ningning Shi, Linbin Luo, Yanxiang Wen, and Xinghui Li "Modeling and test of an absolute four-degree-of-freedom (DOF) grating encoder", Proc. SPIE 12319, Optical Metrology and Inspection for Industrial Applications IX, 123190I (19 December 2022); https://doi.org/10.1117/12.2643904

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