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Browse Prior Art Database

Holographic Store Data Write Verification in Image Photodetector

IP.com Disclosure Number: IPCOM000103051D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 65K

Publishing Venue

IBM

Related People

Brady, JT: AUTHOR [+3]

Abstract

A technique is disclosed for rapid verification of successful writing of a hologram used for digital data storage by priming the holographic image detector with the partial-charge-level complement of expected bit pattern. This permits a simple test for uniform charge level to verify that the digital image was successfully recorded in the hologram.

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This is the abbreviated version, containing approximately 57% of the total text.

Holographic Store Data Write Verification in Image Photodetector

      A technique is disclosed for rapid verification of successful
writing of a hologram used for digital data storage by priming the
holographic image detector with the partial-charge-level complement
of expected bit pattern. This permits a simple test for uniform
charge level to verify that the digital image was successfully
recorded in the hologram.

      To have data integrity dependent on the comparatively high data
indestructibility of a hologram requires an equally high assurance
that the data image was correctly recorded in the hologram [[ that no
errors in the recording path prevented true data image capture.  This
is typically provided in storage device design via a write check
following recording, either via a bit-compare with an
electronically-saved copy of the data source or via an ECC syndrome
calculation.

      The disclosed method precharges the digital image detector with
the complement of the image bit pattern during the same time that the
image bits are being transferred to the storage device writing
element.  At this point, prior to write exposure, the image detector
has all of its bit cells where no charge from the hologram is
expected charged to the equivalent of a '1' bit charge.  Following a
successful hologram exposure, which is observed by the image
detector, all bits in the detector should be uniformly charged to the
level of a data '1' bit.  Any data '1' bits that...