JPS6413516A - Optical scanner - Google Patents

Abstract

PURPOSE:To correct the curvature of image without using an expensive ftheta lens, by providing an actuator for bringing a relative distance on an optical axis of a semiconductor laser and a collimator lens to a reciprocating displacement by allowing it to synchronize with an angle variation of the reflecting surface. CONSTITUTION:The titled scanner is constituted of an optical system for positioning a light emitting point of a semiconductor laser 301 in front on an optical axis from a front focus of a collimator lens 304, and forming an image and executing a scan on the rear scanning surface by following up an angle variation of the reflecting surface of a reflection type optical deflector, and an actuator 32 for bringing a relative distance on an optical axis of the semicon ductor laser 301 and the collimator lens 304 to a reciprocating displacement by allowing it to synchronize with an angle variation of the reflecting surface. In such a way, by executing the reciprocating displacement, a circular arc-like focal plane can be corrected to a linear focal plane. In such a way, a rotary polygon mirror consisting of the reflecting surface on the plane is used, and also, an expensive ftheta lens is not required, and an optical scanner which can correct the curvature of image is obtained.