Mb. Gray et al., A simple high-sensitivity interferometric position sensor for test mass control on an advanced LIGO interferometer, OPT QUANT E, 31(5), 1999, pp. 571-582
A small Michelson interferometer has been configured as a tracking mirror d
isplacement sensor in order to achieve both large dynamic range (2.1 mm) an
d excellent sensitivity (2 x 10(-14) m/root Hz) across a broad frequency ra
nge (6Hz-3 kHz). The interferometer is illuminated by a simple LED, uses br
oadband, non-polarising beamsplitters and contains no lensing optics. A DC-
coupled balanced detector provides an error signal that is used to position
the tracking mirror of the Michelson interferometer so as to maintain an i
nterferometer operating position close to the centre of a particular fringe
. The total interferometric sensor provides a small, simple and cost-effect
ive means of achieving high-resolution displacement measurements.