Optical pickup device

Abstract

Abstract PURPOSE:To attain a tracking control by a high sensitivity 3-beam method with a simple and small constitution, by using a diffraction element to mold integrally a diffraction grating, a horographic grating and an optical means to execute the lens action. CONSTITUTION:A laser beam flux 9 becomes a zero-order diffraction light 9a for focusing and a pair of primary diffraction lights 10a and 11a for tracking by a diffraction grating part 4a of a diffraction grating surface 4 of a diffraction element 2, the diffraction lights 10a and 11a also become the zero-order diffrac tion light by a horographic grating surface 3 of the element 2 and irradiates the disk. The reflecting light is made into a zero-order light by the surface 3, made into 3 sets of primary diffraction lights 9a, 10c an 11c, the longitudinal magnification is expanded by a lens part 4b of the surface 4, made incident on a photodetector 8, and with a simple constitution having a small number of components, the satisfactory tracking error by the high sensitivity 3-beam method is formed.

Inventors

• 👤 Yukio Kurata
• 👤 Hiroshi Ogata
• 👤 Hikari Nishihara
• 👤 Mitsuharu Tomura

Bibliographic Details