Abstract

We present a two-dimensional directional laser Doppler velocimeter (LDV), which is based on the generation of heterodyne signals of different carrier frequencies, so that the different velocity components can be detected simultaneously. The carrier frequencies are generated by a chirp frequency modulation of a diode-pumped monolithic Nd: YAG miniature ring laser in combination with fiber delay lines of a few 100 m lengths. Since this heterodyne technique is based on a completely spliced fiber optic unit without additional frequency shift elements, a simple alignment-insensitive heterodyne LDV system can be realized. Together with the employed Nd:YAG laser, emitting about 1 W single-frequency power, a portable powerful LDV can be realized.

© 1997 Optical Society of America