JP2879368B

PURPOSE:To facilitate adjusting the intersecting angle between the reflected laser light and the transmitted laser light to the proper angle corresponding to the flowing speed in a flowing place by moving a reflecting mirror along the refracting optical axis of a half mirror, turning the mirror together with a supporting shaft, and adjusting the inclination. CONSTITUTION:The half amount of laser light (a) which is transmitted through a half mirror 9 from a laser light oscillator 2 is directly emitted on the same point of a reflecting surface 12 of a rotary mirror 10. The remaining half amount of laser light (b) is refracted with the mirror 9, reflected from a reflecting mirror 8 and cast on the same point of the reflecting surface 12 at the intersecting angle theta with the laser light (a). Emitted lights a1 and b1 which are reflected from the surface 12 are continuously changed into lines a2 and b2 with the rotation of the mirror 10. When the emitted light hits a fluidized particle in the flowing place, two scattering lights of the lights a1 and a2 and the lights b1 and b2 are exposed on the light sensitive surface of a photographing device as the double images. The speed and the direction are obtained based on the change in movement of the fluidized particle within the scanning time of the emitted lights. The angle theta is adjusted in response to the speed of the fluidized particle in the flowing place at the position and the inclination of the mirror 8. Thus, the adjustment becomes easy, and the compact configuration can be obtained.