Patent ID: 6563624
Filing Date: 2003-05-13
Classification: G02B

Abstract:
An optical scanning apparatus, comprising:light source means for emitting light; a first imaging optical system for converging emitted light from said light source means; deflecting means for deflecting converged light from said first imaging optical system; a second imaging optical system for scanning a surface to be scanned with deflected light from said deflecting means; at least one refraction optical element in each of said first imaging optical system and said second imaging optical system; and at least one diffraction optical element in said first imaging optical system or in said second imaging optical system, wherein a power of said diffraction optical element is in a subscanning direction and is set to a third power between a first power and a second power, wherein the first power is a power of said at least one diffraction optical element when a focus movement in the subscanning direction with respect to the surface to be scanned, caused by said at least one refraction optical element with a change of an initial oscillation wavelength of the emitted light, can be canceled by a power change of said at least one diffraction optical element, and wherein the second power is a power of said at least one diffraction optical element when a focus movement in the subscanning direction with respect to the surface to be scanned, caused by said at least one refraction optical element with a change of ambient temperature, can be canceled by a power change of said at least one diffraction optical element.