Patent ID: 7010006

Claim:
A light source device comprising: a semiconductor laser source; a second harmonic generation device for generating a second harmonic from light emitted from the semiconductor laser source; a means for controlling output light power of the semiconductor laser source in such a manner that a power of the second harmonic emitted from the second harmonic generation device is constant; a means for controlling a wavelength of light emitted from the semiconductor laser source; a means for periodically changing the wavelength of light emitted from the semiconductor laser source; and a means for detecting a change in output light power of the semiconductor laser source or a change in an amount of a current injected into the semiconductor laser source that occurs when the wavelength of light emitted from the semiconductor laser source is periodically changed, wherein the wavelength of light emitted from the semiconductor laser source is controlled to an optimum wavelength of the second harmonic generation device based on the change in output light power of the semiconductor laser source or the change in the amount of the current injected into the semiconductor laser source that occurs when the wavelength of light emitted from the semiconductor laser source is periodically changed.