| 摘要 |
PURPOSE:To improve the utilization efficiency of light in displaying, recording and reproducing of information through utilization of laser light and achieve the increase in scanning frequency by letting plural light beams enter a rotary polyhedral mirror at respectively varying incident angles. CONSTITUTION:Incident rays alpha, beta, gamma subsequently enter one reflecting surface 1a of a rotary mirror 1. The reflected scanning rays gamma', gamma' by the rays incident to the end part of the reflecting surface are cut off and only the rays entered near the center of the reflecting surface like the central incident ray beta' are reached to the scanning surface 4 by using a beam selecting plate 6' and said rays are used for scanning. Only the rays near the central portion in the scanning direction suited as scanning rays, of the scanning rays alpha', beta', gamma' being the incident rays alpha, beta, gamma having been reflected by the reflecting surface are selected and used. It is possible to scan always by any of the rays within the rotating angle of one surface by subsequently scanning with three scanning rays, thereby enabling the utilization rate of light to be increased nearly up to 100%. |
