JP2982042B

PURPOSE: To obtain a light condensable aspherical reflection mirror which is capable of well correcting the optical characteristics of a main scanning direction and sub-scanning direction, has a plane tilt correcting mechanism of a polygonal mirror, is capable of making high-density optical scanning and is arranged between a deflector of an optical system for scanning with a light beam and a surface to be scanned. CONSTITUTION: This aspherical reflection mirror Z (X, Y) is formed to a non- circular arc shape Z (Y) within a main scanning plane YZ inclusive of the optical axis X and to a circular arc shape within an arbitrary sub-scanning plane XZ orthogonal with the main scanning plane parallel with the optical axis. The locus connecting the centers of curvature of the circular arcs within the sub-scanning plate is not straight.