Browse Prior Art Database

New Optical Storage Head Using Grating Lenses

IP.com Disclosure Number: IPCOM000036187D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Lean, EG: AUTHOR

Abstract

The conventional optical head for magneto-optic read/write optical storage, as shown in Fig. 1, suffers two key deficiencies. First, it needs a partial polarization beam splitter (PPBS) for the focus and track servo signals. The partial polarization beam splitter can reduce the total throughput of the head by 20 to 30 percent. Secondly, the minimum head profile is limited by the sum of the beam diameter and the focusing lens focal length. The head profile height is important for the volumetric density consideration of the optical storage. The weight of the focusing element plus the attached actuator will determine the speed of the head.

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New Optical Storage Head Using Grating Lenses

The conventional optical head for magneto-optic read/write optical storage, as shown in Fig. 1, suffers two key deficiencies. First, it needs a partial polarization beam splitter (PPBS) for the focus and track servo signals. The partial polarization beam splitter can reduce the total throughput of the head by 20 to 30 percent. Secondly, the minimum head profile is limited by the sum of the beam diameter and the focusing lens focal length. The head profile height is important for the volumetric density consideration of the optical storage. The weight of the focusing element plus the attached actuator will determine the speed of the head.

In this disclosure, an idea for an optical storage head using grating lenses to eliminate the partial polarization beam splitter and to reduce the head profile and weight is discussed. As shown in Fig. 2, the input collimated beam will first pass through a polarization beam splitter (not a partial polarization beam splitter). Two grating lenses are placed 45 degrees with respect to the incident beam. The #2 lens is a reflective grating lens to focus the beam onto a spot on the magneto- optic disk for read/write. Most of the reflected light by the

(Image Omitted)

magneto-optic disk will be reflected back by lens #2 to become a collimated beam traveling backwards. The rotated signals by the magneto- optic disk can then be separated by the polarization beam splitter for detection. 10 to 2...