Hologram

Abstract

Abstract PURPOSE:To simplify an optical system and adjusting operation by providing a hologram face comprising two areas to focus the diffracted light to two different points, respectively to one face, and a diffraction grating face dividing the light beam into three light beams to the other face. CONSTITUTION:A laser beam from a laser light source 1 is divided into three light beams on the diffraction grating face 10B in transmitting through the hologram 10. Then the returned light reflected on a disk signal face via an objective lens 5 is diffracted by a prescribed angle on the hologram face 10A in transmitting through the hologram 10 again and its diffracted light is detected by 6-division photodetector 11. Thus, the detection of a focusing error, a tracking error and a reproducing signal is attained. Thus, the optical system is simplified so as to simplify the adjusting operation and to attain small size and light weight.

Inventors

• 👤 Shiyuuichi Onayama
• 👤 Kazuhiko Nosaka

Bibliographic Details