| 摘要 |
In a pulsed coherent Doppler radar, a Q-switched laser source (12) develops a laser beam to have a high intensity pulse portion (16) and a substantially lower intensity trailing tail portion (18). An acoustic-optic modulator (20) upon which the laser beam is incident directs substantially all of the energy of the pulse portion along a first propagation path (22) towards a target, such as atmospheric aerosols, and substantially all of the energy of the tail portion along the second propagation path (24). The target reflects the pulse portion as a received signal (26). A heterodyne detector (28) upon which each of the received signal and the tail portion is incident, determines the Doppler shift of the received signal with respect to the tail portion. The detector uses the tail portion as the local oscillator. The acousto-optic modulator (20) also upshifts the frequency of the tail protion (18). <IMAGE> |
