| 摘要 |
PURPOSE:To prevent decrease in resolution by shifting the optical frequency of the light entering the light receiving part of a laser radar comprising a light transmitting part and the light receiving part by an acoustic optical modulator, mixing a part of the transmitted light as local oscillation light, and performing heterodyne detection. CONSTITUTION:A light having the frequency nu1 from a master laser ML is divided into light paths (a) and (b) by a half mirror HM1. The light whose power is P2 is in the light path (b) is inputted into a detector D through a mirror 4 and HM2 as local oscillation light. The light in the light path (a) is intermittently flashed by a light switching means CH, amplified, e.g., by about 100,000 times by a TEA amplifier TA, and irradiated to the direction of (d). The light, which is attenuated to power P3 in a light path (e) due to scattering is bent by angle thetaapprox.=4 deg. in the acoustic optical modulator AO. At the same time, the frequency of said light is shifted by a driving frequency of the modulator AO. Said light is inputted to a detector D through a light path (c), a mirror 5, and the HM2, and mixed with the local oscillation frequency from the light path (b). Thus the frequency DELTAnu is obtained and sent to an intermediate frequency amplifier IFA. In this constitution, the stray light component is suppressed to about 1/1,000, and the decrease in resolution can be prevented. |
