Optical pickup

Abstract

Abstract PURPOSE:To obtain a compact and light-weight optical pickup and to shorten the access time of an optical disk memory device, by using a hologram at a primary part of the optical pickup. CONSTITUTION:The dispersed light beams sent from the light emitting point P1 of a semiconductor laser LD11 are turned into the P/S polarized light against thin film holograms 32/31. Thus the hologram 32 is transmitted as it is and diffracted by the halogram 31 to be focused at a point P2 on an optical disk 2. Then the focused hologram 32 passes through a 1/4 wavelength plate 15 to convert the linear polarized light into the circular polarized light. While the reflected and diffracted light sent from the disk 2 travels back and is turned into the linear polarized light by the plate 15 with its polarizing direction orthogonal to the light traveling to the disk 2 from the LD11. This linear polarized light is P/S-polarized to the holograms 31/32 and passes through the hologram 31 to be diffracted by the hologram 32 and then to be focused on a photodetector 18. Furthermore it is possible to detect simultaneously both focusing and tracking errors of an optical pickup by adding a proper aberration to the hologram 32 and dividing the photodetector 18 into four parts.

Inventors

• 👤 Masayuki Kato
• 👤 雅之 加藤
• 👤 Shinya Hasegawa
• 👤 信也 長谷川
• 👤 Fumio Yamagishi
• 👤 文雄 山岸
• 👤 Hiroyuki Ikeda
• 👤 池田　弘之
• 👤 Yushi Inagaki
• 👤 雄史 稲垣

Bibliographic Details