Light beam scanning apparatus
AssigneeFujitsu Limited
InventorsFumio Yamagishi, Shinya Hasegawa, Hiroyuki Ikeda, Takefumi Inagaki
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Abstract
In a light beam scanning apparatus using a hologram rotator, a post-hologram is provided for further diffracting a light beam diffracted by the hologram rotator to a direction opposite to that of the direction in which the light beam is diffracted by the hologram rotator. By combining the kinds of wave fronts used for forming the holograms of the holograms rotator and the post-hologram, the light beam scanning apparatus reduces the deviation of the light beam scanning position caused by the mode hopping of a laser diode, and an improved linear scanning of the light beam and/or image focusing characteristic is obtained.
Claims12
A light beam scanning apparatus comprising:
- a hologram rotator having fringes for diffracting an incident light beam, which is incident on said hologram rotator, having a component of tilt in a first direction from the normal of said hologram rotator, to provide a diffracted light beam exiting said hologram rotator in a direction having a component of tilt substantially opposite said first direction with respect to said normal;
- said post-hologram having fringes, for further diffracting said diffracted light beam in a direction substantially opposite to the direction of said diffracted light beam exiting said hologram rotator, said fringes being such that the light beam from said hologram rotator converges after passing through said post hologram;
- and
- a scanning surface on which said converging light projected from said post-hologram scans in focus.
Dependencies are inferred from the claim text.