Optical pick-up head apparatus wherein hollographic optical elem

Details Optical pick-up head apparatus wherein hollographic optical elem Optical pick-up head apparatus wherein hollographic optical elem

1993-03-23

1994-03-08

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Optical or pre-photocell system

2502015, 369 4423, H01J 314

Patent

active

052930386

ABSTRACT:
An optical pick-up head apparatus to be used for recording and reproducing or erasing optical information on and from an optical storage medium. The head apparatus comprises a semiconductor laser source, a reflector, a reflection type holographic optical element and a photodetector. A laser beam emitted from the semiconductor laser source is incident through the reflector on the reflection type holographic optical element so as to be incident through an objective lens on the optical storage medium. The laser beam reflected and diffracted on the optical storage medium advances along the same path in the opposite direction to be incident on the reflection type holographic optical element to become diffraction beams. The diffraction beams are incident on the photodetector after being reflected on the reflector so as to obtain a focusing error signal, tracking error signal and information signal. The reflection type holographic optical element and the photodetector are formed on one semiconductor substrate, and the semiconductor laser source is disposed to be close to the photodetector on the semiconductor substrate. Due to this arrangement, the head apparatus can easily and accurately be assembled without the positional adjustment of the reflection type holographic optical element or the photodetector, thereby improving the mass productivity of the head apparatus.

REFERENCES:
patent: 4665310 (1987-05-01), Heemskerk
patent: 4737946 (1988-04-01), Yamashita et al.
patent: 4906839 (1990-03-01), Lee
patent: 4929823 (1990-05-01), Kato et al.
patent: 5218584 (1993-06-01), Gfeller

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