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Holograph Imaging Technique

IP.com Disclosure Number: IPCOM000092066D
Original Publication Date: 1968-Aug-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Pennington, KS: AUTHOR

Abstract

Holograms and particularly holograms of diffusely illuminated subjects can be used in high-resolution image projection. It is preferable to use diffuse illumination since the hologram becomes relatively insensitive to minor flaws such as dust particles. However, the reconstructed images are too granular for most uses of projection image such as microcircuitry. If nondiffuse illumination is used, the photographic plate does not have a sufficient dynamic range to record the hologram satisfactorily and the reconstructed image has losses in resolution or contrast. This technique overcomes the mentioned disadvantages.

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Holograph Imaging Technique

Holograms and particularly holograms of diffusely illuminated subjects can be used in high-resolution image projection.

It is preferable to use diffuse illumination since the hologram becomes relatively insensitive to minor flaws such as dust particles.

However, the reconstructed images are too granular for most uses of projection image such as microcircuitry. If nondiffuse illumination is used, the photographic plate does not have a sufficient dynamic range to record the hologram satisfactorily and the reconstructed image has losses in resolution or contrast. This technique overcomes the mentioned disadvantages.

In drawing 1, diffuser screen 2 is located in the Fourier transform plane of subject 4 which can be a transparency. Subject is illuminated by coherent light. A hologram is formed on optically thin photographic emulsion 6 next to screen 2 by the interference of light projected through screen 2 and the light of reference beam 8. After developing emulsion 6 to produce the hologram, it is replaced back in its original position next to screen 2 and illuminated with reference beam 8 as in drawing 2. This results in a conjugate wavefront which is projected through screen 2. At the this conjugate wavefront F*(w(x)w(y)) S*(x,y) is multiplied by the diffuser function S(x,y) yielding F*(w(x)w(y)) S*(x,y); S(x,y); where S(x,y) is the diffuse function and F*(w(x)w(y)) is the conjugate of the Fourier transform of the subject of interest. If...