Patent ID: 7075690
Filing Date: 2006-07-11
Classification: G02B

Abstract:
1. An optical scanning device, comprising: light source means for emitting at least one light flux having a wavelength equal to or smaller than 500 nm; deflection means for deflecting at least one of the light fluxes emitted from the light source means; and a scanning optical system for imaging the light flux deflected by the deflection means onto a surface to be scanned, wherein the scanning optical system consists of a glass lens, a first plastic lens, and a second plastic lens, which are disposed in this order from the deflection means, wherein the glass lens has negative power in the main scanning direction, the first plastic lens has positive power in the main scanning direction, and the second plastic lens has negative power in the main scanning direction, wherein at least one surface of each of the first plastic lens and the second plastic lens in the main scanning direction is aspherical, and wherein the scanning optical system satisfies a relational expression, where ΦG: power of the glass lens in the main scanning direction on an optical axis of the scanning optical system, νG: an Abbe number of the glass lens, ΦP: synthetic power of the first plastic lens and the second plastic lens in the main scanning direction on the optical axis of the scanning optical system, νP: an Abbe number of the first plastic lens and the second plastic lens, and Φ: synthetic power of all systems of the scanning optical system in the main scanning direction on the optical axis of the scanning optical system.