Browse Prior Art Database

Far Field Tracking with Combination Detector

IP.com Disclosure Number: IPCOM000110215D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 52K

Publishing Venue

IBM

Related People

Luecke, FS: AUTHOR

Abstract

The invention disclosed is a track error signal (TES) detector for providing an optimum TES from grooved optical storage media, and requiring only a limited number of additional components. Prior Art Detector A

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Far Field Tracking with Combination Detector

      The invention disclosed is a track error signal (TES) detector
for providing an optimum TES from grooved optical storage media, and
requiring only a limited number of additional components.
Prior Art Detector A

      One prior art detector derives the TES using one multifunction
detector placed between the two closely spaced foci of an anamorphic
lens.  The TES is defined as the difference of intensity between the
light energy on the two halves of the detector.  This arrangement,
with discrimination occurring near the focus, minimizes the parts
required and maximizes the light energy available for data detection.
But it may not provide the best TES and does require critical
alignment.
Prior Art Detector B

      Another prior art detector derives the TES by directing a
fraction of the total light to a large split detector.  This approach
probably produces a better TES with less critical alignment by using
the far-field pattern of the beam, but it also increases the parts
count (cost, size and mass), and reduces the light power available
for data detection.
Proposed Detector

      The proposed detector combines the advantages of far-field
detection (detector B, above) with the simplicity of the nearfocus
arrangement (detector A, above).

      It is believed that there is more information about the
position of the track in the edges of the far-field pattern than in
the center.  Therefore, by modifyi...