Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Correction of Astigmatism for Off Axis Reconstruction Beam Holographic Deflector

IP.com Disclosure Number: IPCOM000051636D
Original Publication Date: 1981-Feb-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Dickson, LD: AUTHOR

Abstract

This article describes the use of a converging reconstruction beam for correcting scan spot astigmatism which is produced where a rotating holographic deflector disc is illuminated with a tilted, collimated beam.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 60% of the total text.

Page 1 of 2

Correction of Astigmatism for Off Axis Reconstruction Beam Holographic Deflector

This article describes the use of a converging reconstruction beam for correcting scan spot astigmatism which is produced where a rotating holographic deflector disc is illuminated with a tilted, collimated beam.

A known type of optical scanner uses a rotating, hologram-carrying disc as a beam-deflecting element. The holograms are arranged in sequence in a circular track on the disc surface.

Each hologram is generated by interfering a coherent reference beam and a coherent object beam at a sheet of photosensitive material. An interference pattern or hologram is recorded in the photosensitive material. If the hologram is later illuminated with a reconstruction beam directed along the path of the original reference beam, the hologram will deflect the beam to reproduce the original object beam.

If the hologram is moving relative to the reconstruction beam, the reconstructed object beam will also move along a scan line.

Normally, the reconstruction beam is directed along a normal to the disc surface; i.e., parallel to the axis of rotation of the disc. There are advantages to using a reconstruction beam which is tilted toward the disc axis of rotation. The deflected beams can be more widely separated while retaining Bragg type diffraction. There is greater flexibility in the location of beam-folding mirrors. Cavity type reflections, which modulate the intensity of the diffracted laser bea...