| 摘要 |
A three-axis, non-scanning, self-referenced laser air data sensing system (1 0) comprises a support (12) having three separate laser diodes (56A-56C) providing beams (22A-22C) of coherent light, which beams (22A-22C) are directed toward separate beam expander mirrors (24A-24C). The expander mirro rs (24A-24C) reflect an expanding beam (26A-26C) back toward a focusing mirror (28) that focuses the beams along three diverging axes (30A-30C) at known angles to each other at three separate locations in space. The focused beams (30A-30C) form small detection cell regions (32A-32C) through which particle s in the fluid pass and reflect light. The reflected light is received back along the same paths (30A-30B; 26A-26C; 22A-22C) as the transmission of the source light, and is directed back toward detectors (70A-70C) on the support (12). The reflected light undergoes a Doppler shift, and this reflected ligh t is combined with a reference signal (66A-66C) tapped from one of the other o f the three coherent light sources (56A-56C) for heterodyning the signals for determining the Doppler shift and thus the relative velocity.
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