Browse Prior Art Database

Enhanced Servo Signals for Optical Data Storage

IP.com Disclosure Number: IPCOM000115567D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Bates, KA: AUTHOR [+3]

Abstract

Data is stored on ablative Write-Once Read-Many (WORM) media by creating holes in the active layer. The areas where the holes are created reflect a very small amount of light. The amount and/or the phase of light reflected when certain data patterns are written is such that the focus and tracking signals derived from the reflected light are severely degraded. This leads to focussing and tracking servo instabilities while writing and reading written data.

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Enhanced Servo Signals for Optical Data Storage

      Data is stored on ablative Write-Once Read-Many (WORM) media by
creating holes in the active layer.  The areas where the holes are
created reflect a very small amount of light.  The amount and/or the
phase of light reflected when certain data patterns are written is
such that the focus and tracking signals derived from the reflected
light are severely degraded.  This leads to focussing and tracking
servo instabilities while writing and reading written data.

      A properly designed multilayer film (10) placed between the
active layer (30) and the substrate (20) will increase the
reflectivity in the areas of the active layer where data is written.
This multilayer is designed to provide the proper reflectivity and
phase shift such that the optical focus and tracking signals
generated have minimal disturbance in the written data area of the
media.  The Figure shows a diagram of a WORM optical disk with the
multilayer (10) added.
      ******************************************************
      *                    20                              *
      ******************************************************
      *                    10                              *
      ******************************************************
      *                    30                              *
      *************************...