| 摘要 |
PURPOSE:To detect the moving speed of a moving body with high accuracy even if laser light varies in wavelength by making desired irradiation luminous flux incident on the moving body and adjusting the inclination of the luminous flux. CONSTITUTION:Speed information on the body 7 is detected by the incidence of luminous flux with wavelength lambda according to the deviation of the frequency of scattered light from the moving body 7. At this time, the laser light from a laser 1 is made into parallel luminous flux 3, which is made incident on the diffraction grating 10k, whose diffracted light beams 5a and 5b of (+n)th order and (-n)th order are reflected by using mirrors 6a and 6b arranged in parallel at the same angle theta1 to irradiate the body 7 in different directions. In this constitution, the angles of diffraction of the diffracted light beams 5a and 5b and the angle theta of incidence on the body 7 vary with the wavelength lambda and the current ratio sintheta/lambda is made nearly constant. Then a photodetector 9 detects scattered light while is Doppler-shifted by the body 7, whose moving speed is detected according to the detection result. At this time, the detection error of the laser light is corrected by the inclination adjustment 12 of the mirror 6a. |
