| abstract |
A laser beam generating device which, by addition of a simplified structure, can enlarge the spectral width of the laser light and lower the coherence to a moderate value. The laser light generating device includes a first laser light source 31, a second laser light source 32, phase modulation units 34, 35 for phase-modulating the beams from the light sources with a sole frequency component or plural frequency components, and an additive frequency generating unit 33 for producing a light beam of the shorter wavelength based on the wavelength of the light phase-modulated by the phase modulation units 34, 30. The fundamental wavelength laser light generated by the first laser light source 31 is phase-modulated by the phase modulation unit 34 based on a pre-set modulation amplitude and the modulation frequency so as to be enlarged in spectral width before being incident on the additive frequency generating unit 33. The additive frequency generating unit 33 generates an additive frequency based on the laser light beams from the light sources for conversion to short wavelengths and for enlarging the spectral width. The result is that the distance of coherence of the outgoing laser light is shortened for removing the speckle noise. |