Displacement Sensing Interferometry
The objective of this project is to design, build and verify a compact displacement measuring interferometry to be used for industrial applications including precise measurements of stage motions and machine control as well as scientific researches on optomechanical sensors for space geodesy. The main research works are focused on optical frequency stabilization, development of novel interferometers and improvement of displacement measurement sensitivity. For the optical frequency stabilization, a thermally stable optical cavity is used, and the optical frequency of the laser can be stabilized with the resonance frequency of the cavity by the Pound-Drever-Hall (PDH) technique. For displacement measuring interferometers, thermally stable heterodyne laser interferometers without periodic errors are designed, built and experimentally verified.
The optical configuration of the heterodyne interferometer adopts spatially separated two frequency beams to prevent frequency and polarization mixing and therefore eliminates periodic errors. The interferometer is also designed to maximize common-mode optical laser beam paths to obtain a high rejection of environmental disturbances, such as temperature fluctuations and acoustics. The results of our experiments demonstrate the short- and long-term stabilities of the system during stationary and dynamic measurements. In addition, we provide measurements that compare our interferometer prototype with a commercial system, verifying our higher sensitivity of 3 pm, higher thermal stability by a factor of two, and periodic-error-free performance. Currently, we have been working on the development of a compact single block interferometer and a fiber interferometer based on spatial separation of two frequency beams and differential type of the configuration.
Researchers Involved:
- Yanqi Zhang
- Felipe Guzman
Relevant Publications:
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A compact high-precision periodic-error-free heterodyne interferometer, J. Opt. Soc. Am. A 37, B11-B18 (2020) – Ki-Nam Joo, Erin Clark, Yanqi Zhang, Jonathan D. Ellis, and Felipe Guzmán