title: Automatic alignment of a displacement-measuring heterodyne interferometer.
abstract: A technique to align automatically the beams of displacement-measuring interferometric gauges is described. The pointing of the launched beam is modulated in a circular pattern, and the resulting displacement signal is demodulated synchronously to determine the alignment error. This error signal is used in a control system that maintains the alignment for maximum path between a pair of fiducial hollow-cube corner retroreflectors, which minimizes sensitivity to alignment drift. The technique is tested on a developmental gauge of the type intended for the Space Interferometry Mission. The displacement signal for the gauge is generated in digital form; and the lock-in amplifier functions of modulation, demodulation, and filtering are all implemented digitally.
authors.affiliation: Mission Research Corporation, Torrance, California 90503, USA.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Logan
authors.forename: Peter G
authors.initials: PG
authors.lastname: Halverson
authors.forename: Martin W
authors.initials: MW
authors.lastname: Regehr
authors.forename: Robert E
authors.initials: RE
authors.lastname: Spero