Patent ID: 8855165

Claim:
A laser apparatus comprising: a cavity provided with reflecting means and output means; a gain member placed on an optical path between said reflecting means and said output means; a wavelength dispersion mechanism configured to disperse a light beam passing through said optical path in accordance with a wavelength thereof; and a wavelength selecting mechanism including a wedge prism which is movable relative to said optical path and changes a traveling direction of a light beam, said wavelength selecting mechanism being configured to change a wavelength of a light beam to be outputted from said output means by being given a gain by said gain member in accordance with a position of said wedge prism, said wavelength dispersion mechanism including a prism which is positioned on said optical path to allow the light beam traveling on said optical path to become incident on said prism at Brewster's angle, wherein said wedge prism has a wedge angle θw which satisfies the relationship: sin( δθ+θw )= n ×sin(θ w ), where δθ represents an angle of separation between a wavelength λ 1 and a wavelength λ 2 by said wavelength dispersion mechanism, and n represents a refractive index of said wedge prism, the wavelength λ 1 being a spectral center wavelength of a light beam outputted when said wedge prism is in a position out of said optical path, the wavelength λ 2 being a spectral center wavelength of a light beam outputted when said wedge prism is in a position on said optical path, and said wedge prism is movable to said position on said optical path in such a manner that said wedge prism is perpendicular to said optical path, wherein the wavelength λ 1 and the wavelength λ 2 are two different wavelengths selected from a range from 700 nm to 800 nm, and said wedge angle θw of said wedge prism satisfies the relationship: 0 °<θw=< 2.88°.