| 摘要 |
PURPOSE:To restrain an unnecessary side band wave so that the deterioration of a resolution may be prevented, by performing a heterodyne detection processing with the assistance of part of a projection laser for local oscillation and a reception light of acoustic optical modulated laser projected outward. CONSTITUTION:Part of a laser beam from a master laser ML is applied to a detector D as a local oscillation light without a side band wave through the intermediary of a half mirror HM1, mirrors 4-6 and a half mirror HM2. In the meantime, the remaining laser beam passing through the mirror HM1 is projected outward after its intermediate frequency was divided and deflected beforehand by means of an acoustic optical modulator AO. This projected laser beam is received and mixed with a local oscillation light by the detector D to undergo a heterodyne detection process. Under the constitution where the projected laser beam is not electrooptically modulated and a local oscillation light acoustically modulated is not used, it is possible to prevent the generation of an unnecessary side band wave and detect a target free from the deterioration of a light resolution based on a monochromatic property. |
