Browse Prior Art Database

Holographic Scanning Element Using Shared Collection Areas

IP.com Disclosure Number: IPCOM000103298D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 47K

Publishing Venue

IBM

Related People

Fortenberry, RS: AUTHOR [+2]

Abstract

It is well known that multiple holograms can be recorded on the same holographic plate and can be reconstructed unambiguously even if they share a common reference beam. One geometry that accomplishes this has the reference beam normal to the plate with the plate rotated between exposures.

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Holographic Scanning Element Using Shared Collection Areas

      It is well known that multiple holograms can be recorded on the
same holographic plate and can be reconstructed unambiguously even if
they share a common reference beam. One geometry that accomplishes
this has the reference beam normal to the plate with the plate
rotated between exposures.

      This article discloses a holographic scanning/light collection
element that uses the principle described above to minimize the
surface area devoted to the light collection task.

      Existing holographic scanner disks use holographic "facets".
Each facet occupies a segment of the disk.  Part of the facet is used
to create the scan line when the disk is rotated in front of a
stationary read beam.  The remainder of the facet is used to collect
light that is scattered back from the scanned object, which is
typically a bar code label.  The left side of Fig. 1 shows such a
holographic disk designed to create three scan lines.  The
holographic regions used to create the three scan lines are marked
1S, 2S and 3S.  The holographic regions used to collect light from
each of the three scan lines are marked 1C, 2C and 3C, respectively.

      The right hand side of Fig. 1 shows a disk created using the
disclosed method.  Using the normal reference beam geometry described
above, the collection hologram for each of the facets is exposed over
the entire disk, excluding the regions used for scanning.  As a
r...