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 journalArticlepeer-review

6 Citations (Scopus)
139 Downloads (Pure)


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
Issue number4
Publication statusPublished - 1 Apr 2019


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