| 摘要 |
PURPOSE:To eliminate a speckle in an output optical beam, by providing an optical element, which changes the relative relation between a laser beam and an input end face of this laser beam in respect to time, in the optical path through which the laser beam is inputted to the input terminal face of an optical fiber. CONSTITUTION:An ultrasonic diffracting element 8A is used as an optical axis changing element. When a high frequency is applied to the ultrasonic diffracting element 8A from an oscillator 11, a laser light 7 passing through the element 8A is diffracted from a non-diffracted light 7a to a diffracted light 7b in accordance with the intensity of the high frequency. The diffracted light 7b is led to an input terminal face 2 of an optical fiber 1 through a lens 9. At this time, when the frequency of the high frequency of the oscillator 11 is changed slightly, the direction of the diffracted light 7b is changed slightly also, and a beam spot 4 on the input terminal face 2 of the optical fiber 2 is changed. Consequently, if the high frequency of the oscillator 11 is subjected to frequency modulation with triangular waves, the beam spot 4 is moved oscillatorily on the input terminal face of the optical fiber, and thus, the influence of the speckle is effaced to secure the vividness of a printed image. |
