Browse Prior Art Database

READOUT ENHANCEMENT BY MASKING FOR MAGNETO-OPTICAL STORAGE SYSTEMS

IP.com Disclosure Number: IPCOM000025115D
Original Publication Date: 1983-Aug-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 69K

Publishing Venue

Xerox Disclosure Journal

Abstract

As shown in relevant part in Figure 1, a large capacity magneto-optic storage system 11 typically requires a high numerical aperture lens 12 to focus a polarized read beam 13 to a small spot on the recording medium 14, so that densely packed data may be resolved. Data is detected by sensing the Kerr and/or Faraday polarization rotation the read beam 13 experiences when reflected from the recording medium 14. For example, such a system may include a beam splitter 15 to allow for through transmission of the incident read beam 13 and to redirect the reflected read beam 16 to a suitable detector 17.

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KEROX DISCLOSURE JOURNAL

READOUT ENHANCEMENT BY MASKING FOR MAGNETO-OPTICAL STORAGE SYSTEMS David Cheng
John C. Urbach

Proposed Classification
U.S. Cl. 369/110 Int. C1. Gllb 7/00

TO READ DETECTOR

/2 I I +" I

Volume 8 Number 4 July/August 1983 367

[This page contains 1 picture or other non-text object]

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READOUT ENHANCEMENT BY MASKING FOR MAGNETO-OPTICAL STORAGE SYSTEMS (Cont'd)

As shown in relevant part in Figure 1, a large capacity magneto-optic storage system 11 typically requires a high numerical aperture lens 12 to focus a polarized read beam 13 to a small spot on the recording medium 14, so that densely packed data may be resolved. Data is detected by sensing the Kerr and/or Faraday polarization rotation the read beam 13 experiences when reflected from the recording medium 14. For example, such a system may include a beam splitter 15 to allow for through transmission of the incident read beam 13 and to redirect the reflected read beam 16 to a suitable detector 17.

As a result of the high numerical aperture of the focusing lens 12, the read beam 13 is brought to focus on the recording medium 14 with a relatively large incident angle. This introduces unwanted depolarization into the reflected read beam 16 due to an ellipsometric effect. See, J. Ben Uri, "Polarization and Interference in Optics," Optik 49, 375 (1978).

The depolarization is strongest in the off axis areas of the reflected beam 16. Thus, as shown in Figure 2, to reduce the degrading eff...