Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1985-07-12
1987-08-18
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
369 45, G01J 120
Patent
active
046879161
ABSTRACT:
An optical pick-up device suitable for use in an optical disk memory system includes a semiconductor laser unit which emits a laser light beam which, in turn, passes through a beam splitter, a quarter-wave plate, and an objective lens to impinge on an optical disc thereby forming a light spot thereon. The light is then reflected from the disc and this reflected light passes through the objective lens and the quarter-wave plate and its direction of advancement is altered by the beam splitter to move into a convergent lens. Then, as the reflected light further advances, it is partly blocked by a tracking error detecting sensor and the remaining non-blocked portion of the reflected light impinges upon a focusing error detecting sensor. The objective and convergent lenses have f.sub.0 and f.sub.1 as their focal distances, respectively, and, preferably, ratio f.sub.0 /f.sub.1 is set equal to or larger than approximately 10.
REFERENCES:
patent: 4085423 (1978-04-01), Tsunoda et al.
patent: 4275275 (1981-06-01), Bricot et al.
patent: 4378491 (1983-03-01), Lehman
patent: 4521680 (1985-06-01), Ando 250201 DF
Emoto Masami
Inuzuka Hideo
Nelms David C.
Oen William L.
Ricoh & Company, Ltd.
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