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Browse Prior Art Database

Illumination for High Precision Photography

IP.com Disclosure Number: IPCOM000092135D
Original Publication Date: 1968-Sep-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Lasky, DJ: AUTHOR

Abstract

This lighting unit, drawing A, provides high-intensity uniform illumination, of good spectral quality, over a large area object plane. Illumination of this kind is needed in high-precision reduction photography used in microminiature circuit device fabrication. The unit housing is backed by an aluminum panel R which reflects and disperses the light for greater uniformity of light at object plane OP. The artwork transparency to be reduced photographically is positioned in plane OP.

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Illumination for High Precision Photography

This lighting unit, drawing A, provides high-intensity uniform illumination, of good spectral quality, over a large area object plane. Illumination of this kind is needed in high-precision reduction photography used in microminiature circuit device fabrication. The unit housing is backed by an aluminum panel R which reflects and disperses the light for greater uniformity of light at object plane OP. The artwork transparency to be reduced photographically is positioned in plane OP.

A bank of thirty standard 8' long fluorescent lamps, mounted horizontally at intervals of two inches center-to-center, supplies the light. Fans, not shown, circulate cooling air over the lamps and through open grillwork G in the top of the unit housing. Alternate lamps, drawing B, are connected to different ballast circuits so that the lamps in the bank can be switched on independently in two groups of fifteen lamps each at 4'' center spacings. Thus two levels of illumination intensity can be supplied with substantially unchanged uniformity and spectral quality, e.g., for different exposure applications.

The lamps operate on 1500 milliampere power groove ballasts producing 195 watts per lamp. The total output of the bank is therefore approximately 6,000 watts. Most of the output light energy is concentrated in a spectral region to which the orthochromatic and high-resolution photographic materials, which are used in such applications, are part...