Optical device

Abstract

Abstract PURPOSE:To reduce the size and weight of a device and the number of parts and to improve the assembling accuracy of the device by forming a diffraction grating and a Fresnel zone plate on the front and back surfaces of an optical glass plate respectively and providing the device with an optical beam dispersing function and a collimating function. CONSTITUTION:The optical device 10 obtained by forming a diffraction grating on the front surface of an optical glass as shown by slashes and forming a Fresnel zoon plate on the back surface and arranged in an optical system for optical information processing, photometry, etc. is used to collimate a diffused light from a semiconductor laser 1 e.g. by the Fresnel zoon plate and divide the collimated light into three beams by the diffraction grating. The three beams are converged on an optical disk 7 through a beam splitter 5 and an objective lens 6 and the reflected light from the disk 7 is polarized in the direction of a lens 8 by the beam splitter 5 to lead only he light corresponding to pits on the disk 7 into a detector 9. Said constitution makes it possible to obtain the device reduced at its size and weight and improved at its assembling accuracy.

Inventors

• 👤 Koji Yamashita
• 👤 山下　光二

Bibliographic Details