Photomagnetic head apparatus

Details Photomagnetic head apparatus Photomagnetic head apparatus

1997-07-10

1998-12-15

Edun, Muhammad N.

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

369112, 369109, 369118, 369 4437, G11B 7135

Patent

active

058503803

ABSTRACT:
A photomagnetic head apparatus includes a beam splitter which splits a laser beam, reflected by concentric recording tracks of a rotating photomagnetic recording disc, into three bundles of rays. The three bundles of rays have different polarization directions in a plane which lies in a radial direction of the recording tracks. One of the three bundles of rays is used as a servo-signal light, and the remaining two bundles of rays are used as data signal lights. A defocusing diffraction element splits at least the servo-signal light into a least two bundles of rays in a direction corresponding to the tangential direction of the recording tracks, substantially perpendicular to the split direction of the beam splitter and which provides at least two split lights with a predetermined amount of positive or negative defocus in an optical axis direction. A pair of servo-signal light receiving elements receive the split beams of the servo-signal light produced by the defocusing diffraction element. A data light receiving element receives the data signal lights. The defocusing diffraction element is made of a non-circular element whose numerical aperture in the tangential direction of the recording tracks is smaller than the numerical aperture in the radial direction.

REFERENCES:
patent: 4951274 (1990-08-01), Iwanaga et al.
patent: 5231620 (1993-07-01), Ohuchida
patent: 5247508 (1993-09-01), Tanaka
patent: 5272685 (1993-12-01), Ando
patent: 5278401 (1994-01-01), Takishima et al.
patent: 5280464 (1994-01-01), Itoh et al.
patent: 5293371 (1994-03-01), Koyama
patent: 5293569 (1994-03-01), Koyama
patent: 5309423 (1994-05-01), Noguchi et al.
patent: 5315574 (1994-05-01), Saimi et al.
patent: 5337300 (1994-08-01), Takishima et al.
patent: 5453963 (1995-09-01), Katayama et al.
patent: 5491675 (1996-02-01), Kay
patent: 5493555 (1996-02-01), Kimura et al.
United Kingdom Search Report of U.K. Patent Application No. 9507188.2.
Patent Abstract of Japan, vol. 18, No. 089 (P-1692).
French Search Report of French Application No. FR 9504092.

Affiliated with

Also associated with

Rating

Photomagnetic head apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Photomagnetic head apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photomagnetic head apparatus will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1462935