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Process for Making a Dichromated Gelatin Holographic Disk

IP.com Disclosure Number: IPCOM000042318D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Beam, DL: AUTHOR [+3]

Abstract

A process has been developed for producing optically clean dichromated gelatin "submasters" from a silver halide master hologram disk. The submaster disks are used as surrogate masters in making production quantities of dichromated gelatin disks. A dichromated gelatin mixture consisting of 43% ammonium dichromate to Knox 2640 gelatin (by weight) is prepared. An example is 6.5g dichromate/15g gelatin/100ml H2O at 70ŒC. The substrate is coated by spinning the disk at 65 rpm for 10 minutes with enough mixture applied to produce a film 4.0-5.0 microns thick. After coating, the film is cured at 63ŒC/37% relative humidity for a period of time required to give the film a cure level compatible with the exposure and developing cycles to follow.

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Process for Making a Dichromated Gelatin Holographic Disk

A process has been developed for producing optically clean dichromated gelatin "submasters" from a silver halide master hologram disk. The submaster disks are used as surrogate masters in making production quantities of dichromated gelatin disks. A dichromated gelatin mixture consisting of 43% ammonium dichromate to Knox 2640 gelatin (by weight) is prepared. An example is 6.5g dichromate/15g gelatin/100ml H2O at 70OEC. The substrate is coated by spinning the disk at 65 rpm for 10 minutes with enough mixture applied to produce a film
4.0-5.0 microns thick. After coating, the film is cured at 63OEC/37% relative humidity for a period of time required to give the film a cure level compatible with the exposure and developing cycles to follow. The disk is then placed in an exposure fixture so as to minimize the separation between the master hologram and the submaster film. The master hologram is illuminated with argon laser radiation at 488 nm at an appropriate reference angle. Exposure energy is typically 35 microjoules/cm2 at 7.7 milliwatts/cm2 for the optical properties of the specific master and submaster holographic films exercised in this study. Following exposure, the film goes through a fixing and developing sequence which includes a 15-minute water soak at 60OEC. Normal efficiencies at this stage are typically 50-70%. For submasters to have the proper zero order to first order beam reconstruction ratio...