A frequency-modulated laser interferometer for nanometer-scale position sensing at cryogenic temperatures

Adam J. Christiansen; David A. Naylor; Ian T. Veenendaal; Brad G. Gom

doi:10.1117/12.2508900

4 March 2019 A frequency-modulated laser interferometer for nanometer-scale position sensing at cryogenic temperatures

Adam J. Christiansen, David A. Naylor, Ian T. Veenendaal, Brad G. Gom

Proceedings Volume 10925, Photonic Instrumentation Engineering VI; 1092514 (2019) https://doi.org/10.1117/12.2508900
Event: SPIE OPTO, 2019, San Francisco, California, United States

Abstract

The continually increasing sensitivity required for advancement of far-infrared astronomy dictates that the next generation of space-based observatories must employ cryogenically cooled telescopes and instruments. Cryogenic operation of interferometers such as those proposed for future space missions poses particular challenges, including the need for robust low power dissipation cryogenic position metrology. Instrumentation must be cooled to <4 K to avoid a noise contribution from self-emission and often contain moving components whose position must be measured precisely at cryogenic temperatures. In 2018, we reported on the development of a three-phase fiber-fed laser homodyne interferometer for optical position metrology that achieved a displacement uncertainty of 2.3 nm RMS at 4 K. In that design, one arm of the interferometer had an additional 2 m of optical fiber to carry the probe signal to the 4 K work space. Subsequently, a 2 m, armored, differential fiber pair was developed to balance the lengths of the probe and reference interferometric beams that were subject to thermal gradients. Although this led to an improved dynamic performance in the measurement of an oscillating target, low velocity performance was limited by 1/f noise in the photodetector circuit. Building on that work, we present the design and review the performance of a new frequency-modulated laser interferometer system we have developed that improves upon the three-phase system by eliminating the need for a differential fiber pair in cryogenic applications and achieves 29 nm RMS uncertainty for mechanical displacement velocities from 0 to ~4 mm/s.

Conference Presentation

Citation Download Citation

Adam J. Christiansen, David A. Naylor, Ian T. Veenendaal, and Brad G. Gom "A frequency-modulated laser interferometer for nanometer-scale position sensing at cryogenic temperatures", Proc. SPIE 10925, Photonic Instrumentation Engineering VI, 1092514 (4 March 2019); https://doi.org/10.1117/12.2508900

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