A PC-interfaced, compact laser-diode feedback interferometer for displacement measurements

We describe a laser-diode feedback interferometer for displacement measurements with directional discrimination and resolution better than 10/sup -6/ m. This new, compact instrument consists of a small optical head and a signal processing board, which is interfaced to a personal computer. The prototype developed has a dynamic range of 2 m and an accuracy of about 5 /spl mu/m/m, using a corner cube as a remote reflector. Thanks to PC interfacing, the displacement is directly available in metric units and errors due to temperature fluctuations can be corrected with software signal processing.