| 摘要 |
PURPOSE:To decrease a number of parts and to reduce an assembling error by using a planar reflection mirror having focusing function in a plane tilt compensating optical system. CONSTITUTION:A laser writing device oscillates a semiconductor laser 1 by means of a modulating signal modulated by pulse width, a laser beam is deflected by a polygon mirror 4 rotating at a prescribed speed, converged to a minute spot and scanned on an image carrier 8 by means of an ftheta lens 5 and a planar reflection mirror 7. A collimator lens 2 is a modulating optical system, the polygon mirror 4 and the ftheta lens 5 are deflection optical system and the planar reflection mirror 7 is a plane tilt compensating optical system having focusing function by using Lippman-type hologram. Namely, since the plane tilt compensating optical system is the planar reflection mirror 7 having focusing function, a cylindrical lens, etc., is not required to be added in a scanning optical system, a number of parts is decreased and, consequently, an assembling error is reduced. |
