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Phase Holograms

IP.com Disclosure Number: IPCOM000091411D
Original Publication Date: 1968-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Max, E: AUTHOR [+4]

Abstract

Holograms are interference patterns recorded in a light-sensitive medium. There interference patterns can affect either the amplitude or phase of the transmitted light or both. The first described holograms which are known as absorption holograms have the disadvantage of great light attenuation and severe light scattering.

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Phase Holograms

Holograms are interference patterns recorded in a light-sensitive medium. There interference patterns can affect either the amplitude or phase of the transmitted light or both. The first described holograms which are known as absorption holograms have the disadvantage of great light attenuation and severe light scattering.

These disadvantages are not encountered with true phase holograms. However phase holograms made by methods, where the shrinkage is caused by the removal of the nonexposed silver halides by the fixing bath, always display to a certain degree the properties of absorption holograms. This is because the silver of an absorption hologram is bleached, i.e., reconverted to silver halide subsequent to the fixing process, the halide being left in the gelatine layer.

Due to this silver halide still present in the emulsion, the resulting hologram is not fully transparent. Furthermore, the relief structure of these holograms is very slight. This is because only a relatively small amount of shrinkage can be realized by the removal of the silver halide during the fixing process. These disadvantage can be avoided by the following process.

A hologram is made in the conventional manner. That is, a light sensitive emulsion is exposed to the interference patterns to be recorded, put into a developer bath and subsequently in a short stop and water bath. In this process, the emulsion is put subsequently into a combined bleaching and etching bath cons...