We have introduced the techniques of phase-shifting interferometry into a laser feedback interference microscope based on a helium–neon laser. With moderate feedback, multiple reflections between the sample and the laser are shown to be negligible, and the interferometer responds sinusoidally with a well-characterized fringe modulation. One can obtain higher signal-to-noise ratios by determining the number of additional terms required for modeling the effect of multiple reflections on the phase and visibility measurements in the high-feedback regime. Changes in optical path length are determined with nanometer precision without phase averaging or lock-in detection.
© 1998 Optical Society of America
(110.0180) Imaging systems : Microscopy
(110.6880) Imaging systems : Three-dimensional image acquisition
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.5050) Instrumentation, measurement, and metrology : Phase measurement
(180.3170) Microscopy : Interference microscopy
Ben Ovryn and James H. Andrews, "Phase-shifted laser feedback interferometry," Opt. Lett. 23, 1078-1080 (1998)