Optical head

Abstract

Abstract PURPOSE:To obtain a compact optical head by performing the photodetection after making the light reflected by either one of a focusing or tracking photodetector incident on the other photodetector. CONSTITUTION:The laser beams radiated from a semiconductor laser 50 are turned into parallel beams by a collimator lens 52 and converged on an optical disk 62 by an objective lens 60 after passing through a beam splitter 56. The half of the light beams reflected by an optical disk 62 is separated by the splitter 56 to produce the asigmatism by a lens 66 and a rod lens 68. Then a focus signal is detected by a photodiode 70. At the same time, the reflected light of the photodiode 70 travels back to pass through the splitter 56 and the polarized wave surface is turned by 45 deg. by a 1/2 wavelength plate 72. Then the reflected light is divided into two directions by a beam splitter 76 via a lens 72 and made incident on the photodiodes 78 and 80 of a tracking photodetectors.

Inventors

• 👤 Takayuki Nakano
• 👤 中野　尊之

Bibliographic Details