RANGE FINDING AND VELOCIMETRY WITH DIRECTIONAL DISCRIMINATION USING AMODULATED LASER-DIODE MICHELSON INTERFEROMETER

A dynamic laser interferometer for ranging and velocity measurements u sing a modulated laser diode as light source in an unbalanced Michelso n configuration is described. The technique uses the fact that the wav elength of the emitted light varies linearly with the injection curren t. When the diode's injection current is modulated in a triangular wav e, a heterodyne beat signal is generated with a frequency proportional to the optical path difference. When the target is moving, the techni que allows absolute distance measurement with directional discriminati on as well as target velocity. The device is described and experimenta l results are presented.