A laser walk-off sensor for high-precision low-frequency rotation measurements

J. J. McCann, J. Winterflood, L. Ju, C. Zhao

Research output: Contribution to journalArticle

2 Citations (Scopus)
139 Downloads (Pure)

Abstract

We present an optical walk-off sensor with an angular sensitivity of a few nrad/Hz above 1 mHz and 0.4 nrad/Hz above 100 mHz. This experiment furthers previous research into the walk-off sensor capabilities through an improved input laser, reduction in air optical travel length, and position control on photo-diodes. The angle change measured in this walk-off scheme features a knife edge to split the beam into two separate fiber coupled photo-diodes to minimize power dissipation in the thermally sensitive region. Using this photo-diode power differential as an error signal, a simple control scheme is used to maintain the balance position, increasing common mode rejection and improving dynamic range by mitigating thermal drift. The in-vacuum component of the optical readout takes up a volume less than 100 mm × 100 mm × 50 mm. This experiment shows that the walk-off sensor provides a simple and compact readout scheme with nanoradian sensitivity for angle sensing at low frequencies.

Original languageEnglish
Article number045005
Number of pages6
JournalReview of Scientific Instruments
Volume90
Issue number4
DOIs
Publication statusPublished - 1 Apr 2019

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