JPS5683175A - Optical beam scanner correcting uneven pitch of scanning line - Google Patents

Abstract

PURPOSE:To remove uneven pitch of scanning line on the surface to be scanned, by measuring the amount of slope for a plurality of parts on one polarized reflection surface, and determining the slope of the deflected reflection plane based on a plurality of information. CONSTITUTION:Light beam 32 is split and picked up from the laser beam 22 at a half mirror 31. Further, after the beam 32 is split to detection beams 34, 35 with the half mirror 33, it is incident to the polarized reflection plane 28c, where the failling is measured. The beams 34, 35 reflected on the plane 28c are respectively incident to the fixed sensors 37, 38. From the falling detection signal on the reflection mirror surface detected at the two points on the plane 28c at the same time, the slope of the plane 28c can linearly be approximated. The amount of slope of the plane 28c is stored, and when the plane 28c turns and reaches a position deflecting the main scanning beam, the stored information is picked up and fed to the device driving an audio optical element 24 as a correction value. Further, the position of optical beam on the surface 20 to be scanned can be corrected by amount DELTA to prevent the distortion of picture.