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Minimizing Chromatic Aberration in a Holographic Optical Element

IP.com Disclosure Number: IPCOM000051166D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Dickson, LD: AUTHOR

Abstract

This article describes a technique for minimizing chromatic aberration in a multi-focal plane holographic disk scanner when the recording laser produces light at one wavelength while the playback laser produces light at a different wavelength. Basically, the recording process uses a collimated reference beam and diverging, collimated or converging object beams, depending upon the desired focal length of a given holographic optical element (HOE) on the disc. During playback, a focusing lens is employed to provide focusing power for the reconstructed beam. The technique is described in more detail in the remainder of this article.

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Minimizing Chromatic Aberration in a Holographic Optical Element

This article describes a technique for minimizing chromatic aberration in a multi-focal plane holographic disk scanner when the recording laser produces light at one wavelength while the playback laser produces light at a different wavelength. Basically, the recording process uses a collimated reference beam and diverging, collimated or converging object beams, depending upon the desired focal length of a given holographic optical element (HOE) on the disc. During playback, a focusing lens is employed to provide focusing power for the reconstructed beam. The technique is described in more detail in the remainder of this article.

To reduce the cost of a laser scanner having a multi-focal plane holographic disc, it would be desirable to use a GaAs semiconductor laser as the playback light source. To eliminate chromatic aberration, a GaAs laser could be used as the recording light source employed in making the master facets from which the final or production holographic discs are copied. However, the preferred recording material (silver halide, high resolution emulsion) for making the master facets is not sensitive at the wavelength of light produced by a GaAs laser.

To minimize chromatic aberration where the recording laser is a helium/neon laser while the playback laser is a GaAs laser, the following steps are employed. First, to simplify matters, assume that it is desired to have a production disc w...