Title:
HOLOGRAM ELEMENT
Document Type and Number:
Japanese Patent JPH01149235
Kind Code:
A
Abstract:
PURPOSE:To adjust a returning light from a photo-diode output to the center of a photo-diode by equipping the third area of a grid pattern to form a focus in the middle of the focal position of a first area and a second area and to be a symmetrical shape concerning the dividing line of the first area and the second area. CONSTITUTION:When a hologram element 3 is used as the hologram element in a hologram optical head, for example, a light, which is diffracted by the hologram element 3 of the returning light to be reflected by a disk signal surface, goes toward an optical detector 6 to have four-dividing photo-diodes A-D. In such a case, to the four-dividing photo-diodes on the optical detector 6, a spot by a third area III is formed in the central position of the four-dividing photo-diodes A-D together with the spots by the first area I and the second area II of the hologram element 3. Accordingly, when the spot dislocation of the returning light is generated on the optical detector 6, the spot by the third area III is deviated right and left from the center of the four-dividing photo-diode A-D. Thus, the spot dislocation of the returning light can be adjusted from the outputs of the four-dividing photo-diodes A-D.
Inventors:
ONAYAMA SHIYUUICHI
ONO YUZO
KIMURA YASUO
NOSAKA KAZUHIKO
IKEDA TETSUTO
ONO YUZO
KIMURA YASUO
NOSAKA KAZUHIKO
IKEDA TETSUTO
Application Number:
JP30718887A
Publication Date:
June 12, 1989
Filing Date:
December 04, 1987
Export Citation:
Assignee:
NIPPON DENKI HOME ELECTRONICS
NEC CORP
NEC CORP
International Classes:
G03H1/00; G02B5/32; G11B7/135; (IPC1-7): G02B5/32; G03H1/00; G11B7/135
Domestic Patent References:
| JPS6111947A | 1986-01-20 | |||
| JPS60106039A | 1985-06-11 | |||
| JPS56158319A | 1981-12-07 |
Attorney, Agent or Firm:
Yasuhiko Kagawa