Patent ID: 8840251

Claim:
A light collecting optical system comprising: a first-wavelength surface-emitting light source having a first wavelength light emitting surface and emitting first wavelength light from the first-wavelength light emitting surface; a second-wavelength surface-emitting light source having a second wavelength light emitting surface and emitting second wavelength light from the second-wavelength light emitting surface, the second wavelength being shorter than the first wavelength; a first-wavelength collimate lens having a positive power and collimating the first wavelength light emitted from the first-wavelength light emitting surface; a second-wavelength collimate lens having a positive power and collimating the second wavelength light emitted from the second-wavelength light emitting surface; a light synthesis means for synthesizing the first wavelength light that passed through the first-wavelength collimate lens and the second wavelength light that passed through the second-wavelength collimate lens; a condenser lens having a positive power and condensing the synthesized light; and a light-intensity-distribution uniformizing element having an incident surface for receiving light condensed by the condenser lens and having an exit surface for outputting light, a light intensity distribution of which is uniformized; wherein: the first-wavelength light emitting surface and the second-wavelength light emitting surface have a rectangular shape having the same size and a similar figure to the incident surface of the light-intensity-distribution uniformizing element; the first-wavelength collimate lens and the second-wavelength collimate lens have the same structure; the first-wavelength collimate lens and the second-wavelength collimate lens are arranged so that an optical distance from the first-wavelength collimate lens to the condenser lens and an optical distance from the second-wavelength collimate lens to the condenser lens become approximately same; and the first-wavelength surface-emitting light source and the second-wavelength surface-emitting light source are arranged so that the first-wavelength light optical distance from the first-wavelength light emitting surface to the first-wavelength collimate lens is longer than the second-wavelength light optical distance from the second-wavelength light emitting surface to the second-wavelength collimate lens, and a secondary light source image of the first-wavelength light emitting surface imaged on the incident surface of the light-intensity-distribution uniformizing element by the first-wavelength collimate lens and the condenser lens and a secondary light source image of the second-wavelength light emitting surface imaged on the incident surface of the light-intensity-distribution uniformizing element by the second-wavelength collimate lens and the condenser lens have the same size.