optical scanning device

Abstract

Abstract PURPOSE:To vary scanning line density, i.e. resolution easily only shifting operation of an incident beam in position by using a hologram disk which has plural concentric diffraction tracks differing in grating pitch. CONSTITUTION:The hologram disk 3 is formed by providing circular diffraction tracks 2a and 2b arranged concentrically on a disk 1, and plural diffraction gratings provided on each track are formed in a hologram as straight-line diffraction gratings so that the outside track 2b is smaller in grating pitch than the inside track 2a. Projection light from a semiconductor laser LD is collimated by a lens L1 and expanded by a beam expander BE to a proper beam diameter. The laser beam is made incident to a track on the disk 3 through a mirror M1 or M3 selectively according to the switching of scanning line density. The beam is diffracted to generate scanning light, which is reflected by a mirror M2 or M4 to enter an ftheta lens L2, scanning on a scanning surface F.

Inventors

• 👤 Hiroyoshi Funato
• 👤 広義 船戸

Bibliographic Details