Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore

A Compact Differential Heterodyne Laser Interferometer without Periodic Errors

Ki-Nam Joo1,a, Erin Clark2, Yanqi Zhang2,3, Felipe Guzman3 and Jonathan D. Ellis4

1Dept. of Photonic Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju, 61452, South Korea

2College of Optical Sciences, University of Arizona, 1630 E. University Blvd., Tucson, AZ 85721, USA

3Department of Aerospace Engineering, Texas A&M University, 701 H.R. Bright Bldg., College Station, TX 77843, USA

4Clerio Vision Inc., 1892 S. Winton Rd., Rochester, NY 14618, USA


In this investigation, we propose a thermally stable heterodyne laser interferometer with the spatial beam separation. The optical configuration is designed for the differential type and the reference signal only measures the systematic phase noise in the interferometer while the measurement signal includes both of the displacement of the target and the systematic noise. Then, the phase noise, especially thermal drift caused by the interferometric optics can be canceled out. Furthermore, the spatial separation of two beams can prevent frequency and polarization mixings in the interferometer. In the experiments, long- term stability of the system was estimated, and the measurement results were compared with those of the commercial DMI system. As the result, it was confirmed the periodic nonlinear errors were not detectable in the proposed interferometer while the commercial DMI system has the first order periodic error 0.6 nm.

Keywords: Heterodyne laser interferometer, Periodic error, Differential interferometer

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