Patent ID: 8547814

Claim:
A semiconductor laser device comprising: a plurality of light sources that emit light beams having different wavelengths; and a diffractive element that diffracts a light beam so that an optical axis of a light beam having a wavelength emitted from one of two light sources among the plurality of the light sources is made in alignment with an optical axis of a light beam having a different wavelength emitted from the other of the two light sources, the diffractive element having a diffractive area where the light beam emitted from the one of the two light sources is diffracted with an angle which is formed by the optical axis of the light beam emitted from the one light source and the optical axis of the light emitted from the other light source so that a light beam which is emitted from the one light source and diffracted by the angle is aligned with a light beam which is emitted from the other light source and transmitted through the diffractive element, wherein an optical path length between the diffractive element and a light originating point of the one of the two light sources is equal to an optical path length between the diffractive element and a light originating point of the other of the two light sources, and the diffractive element diffracts the light beam emitted from the one of the two light sources so that an imaginary light originating point of the one of the two light sources coincides with the light originating point of the other of the two light sources.