Abstract

A compact self-aligning laser radar has been constructed for coherent ranging and velocimetry using a laser diode modulated by feedback from light scattered from a diffusing target. The phenomenology of beat-signal generation in the device is discussed from both experimental and theoretical points of view. The ac-coupled modulation waveform is asymmetric (similar to a sawtooth) and different for the two propagation directions of the light leaving the diode. A theoretical model, based on the mode structure of a three-mirror Fabry-Perot cavity, is shown to describe the signal generation in these experiments, to account for the sawtooth waveform, and to predict the modulation depth of the waveform. Possible applications and extensions of this technology are briefly discussed.

© 1988 Optical Society of America