Patent ID: 7397590
Filing Date: 2008-07-08
Classification: G02B

Abstract:
1. An optical scanning apparatus comprising: a light source; a deflection unit configured to deflect a light flux emitted by the light source; a first optical system configured to condense, at the deflection unit, a divergent light flux emitted by the light source; a second optical system configured to focus, on a target scanning face, the light flux deflected by the deflection unit, wherein the wavelength of the light flux emitted by the light source is 450 nm or shorter, and a first refractive optical element made of plastic is arranged in the second optical system, and a first diffractive optical element having a diffraction surface is arranged in the first optical system, and power for the first refractive optical element in a main scanning direction and power for the diffraction surface of the first diffractive optical element in the main scanning direction have the same sign, and a ratio of the power of the first refractive optical element in a main scanning direction to the power of the first diffractive optical element in the main scanning direction is set so that a focus change caused by a power change at the first refractive optical element is compensated for by using a focus change that is produced by a power change at the first diffractive optical element.