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10-pm-order mechanical displacement measurements using heterodyne interferometry
Applied Optics Số 27, năm 2020 (Tập 59, trang 8478-8485)
DOI: 10.1364/AO.400682
Tài liệu thuộc danh mục: ISI, Scopus
OSA - The Optical Society
English
Từ khóa: Field programmable gate arrays (FPGA); Floors; Heterodyning; Interferometers; Interferometry; Phase locked loops; Different frequency; Environmental noise; Heterodyne interferometer; Heterodyne interferometry; Measurement comparison; Measuring systems; Mechanical displacements; Phase Locked Loop (PLL); Displacement measurement
Tóm tắt tiếng anh
In this paper, we present 10-pm-order mechanical displacement measurements using heterodyne interferometry. The measuring system includes a single-path heterodyne interferometer and a phase meter based on a phase-locked loop (PLL). It is not easy to measure a mechanical displacement of 10 pm or less owing to electronics and environmental noises in the interferometer. To solve this problem, the improvement of the noise floor is required for the phase meter. A PLL algorithm, which is programmed on a field-programmable gate array module, is used for efficient noise reduction of the phase meter. The interferometer combined with a stiff piezoelectric flexure stage is placed in a vacuum chamber. The measurement comparisons and the noise floor evaluations are performed between air and vacuum to evaluate effects from their environments. The interferometer has two spatially separated beams with different frequencies and two balanced optical arms. The measurement results demonstrate that the system combined with the above components is capable of measuring mechanical displacements of 11 pm in air and vacuum. A noise floor of 0.2 pm/√Hz between 50 Hz and 100 Hz can be obtained in vacuum. In this paper, the setup of the interferometer, the signal processing of the PLL, experiments, and results are discussed. © 2020 Optical Society of America
