High accuracy laser Doppler velocimeter using stable long-wavelength semiconductor lasers.

Doppler velocimeters for remote velocity sensing require a compact and miniaturized system. We report the achievement of an eye-safe Doppler velocimeter at 1.54microm using InGaAsP diodes reduced in linewidth by external cavity stabilization techniques. Linewidth of the diodes was of the order of 40 kHz allowing for a sub-cm/s velocity resolution over long distances (i.e., 100 m).