| 摘要 |
PURPOSE:To prevent speckle noises effectively by phase-modulating semiconductor layer rays through ultrasonic waves. CONSTITUTION:Laser rays generated from the semiconductor laser 1 are focussed by means of a lens 2, phase-modulated through ultrasonic waves at an ultrasonic transmitter 4 and projected to the optical fiber 5. Ultrasonic vibration is generated at a piezo-electric element 3, and transmitted to the ultrasonic transmitter 4. Consequently, since the incident conditions of the phase, etc. of the laser rays at an incident surface of the optical fiber 5 are changed periodically in accordance with a period of the ultrasonic vibration, interference conditions in the optical fiber 5 alter, and a position and a form of a speckle change. Accordingly, the speckle in the optical fiber 5 is smoothed and the speckle noises can be reduced by generating ultrasonic waves at frequency higher than the frequency of modulation signals applied to the semmiconductor laser 1. |
