Patent ID: 6507445
Filing Date: 2003-01-14
Classification: G02B

Abstract:
An optical system, for use with a light source that emits light of a reference wavelength, provided with a lens, a stop and a diffraction grating, characterized in that (i) when in a state wherein said diffraction grating is absent, and the value of the coefficient of chromatic aberration of magnification of the wavelength of the long wavelength side relative to the reference wavelength of said light source is positive, said diffraction grating is disposed more adjacent to an incidence surface side than said stop, and (ii) when in the state wherein said diffraction grating is absent, and the coefficient of chromatic aberration of magnification of the wavelength of the long wavelength side relative to the reference wavelength of said light source is negative, said diffraction grating is disposed more adjacent to an emergence side than said stop,wherein said diffraction grating is disposed between said stop and a lens disposed nearest to said stop and is independent of said lens and stop, and said optical system has four or less lenses.