| 摘要 |
PURPOSE:To improve the utilization efficiency of light in an optical scanner using a linear diffraction grating by making the oscillation plane for polarization of incident light coincident with the grating direction of holograms when the center of scanning lines is scanned. CONSTITUTION:The oscillation plane for polarization of an illumination beam for reproduction is set in the grating direction of holograms, that is, in the radial direction of a disc 3 under rotation at a constant speed in an optical scanner which is disposed concentrically with plural pieces of holograms on the disc 2 and scans a scanning plane P by the primarily diffracted light of the laser beam incident to the holograms. The individual holograms 21, 22... of the disc 2 have a linear grating and since the grating is disposed at a right angle to the radius of the disc running the center thereof, the grating direction of the holograms and the oscillation plane for polarization of the incident beam coincide in the stage of scanning the center P0 of the plane P and the max. diffraction efficiency is shown; at the same time, the decrease in the efficiency at the starting point P1 of scanning and the end point P2 of scanning is minimized. |
