Patent ID: 8305681

Claim:
A light source apparatus, comprising: a laser source for producing a fundamental laser beam; a first nonlinear optical crystal converting the incident laser beam to produce a harmonic laser beam; first polarization adjusting means arranged in the optical path between the laser source and the first nonlinear optical crystal and adjusting the polarization state of the incident laser beam based on a first control signal at high speed; second polarization adjusting means arranged in the optical path between the laser source and the first nonlinear optical crystal and adjusting the polarization state of the incident laser beam based on a second control signal at low speed than the first polarization adjusting means; a photodetector receiving a part of the output beam emitted from the first nonlinear optical crystal to produce an electric signal corresponding to the intensity of the output beam; and control means for producing the first and second control signals used to control respectively the first and second polarization adjusting means using the output electric signal from the photodetector.