The Metal-Diazonium System for Photographic Reproductions

The metal-diazonium system for photographic reproduction, which has been developed in Philips Laboratory in Eindhoven in the course of the last few years, is based on the discovery that when a solution of a diazonium compound and a metal salt, say mercurous nitrate, is exposed to light, atomic metal — in casu mercury — is separated. The “latent” mercury image thus obtained can be transformed by physical development into a silver image and intensified. The light-sensitive system is obtained in the form of a film or sheet by impregnating a suitable carrier, say a strip of cellophane 40 μ thick, in a homogeneous solution of the said materials. The metal-diazonium system possesses an extremely high resolving power (> 1000 lines/mm) and allows of working with a very high gamma (6-8) while on the other hand low gammas (1-2) can also easily be obtained by varying external factors, viz. the moisture content or the intensity of exposure. The light-sensitivity of the system is in cellophane several times (in paper some tens of times) greater than that of the usual diazotype printing papers. This system, which was originally intended only for producing distortion-free copies of Philips-Miller sound film, lends itself excellently, inter alia, for the copying of picture-sound films, thanks to the external variability of the gamma. The impregnating of the cellophane base takes place on printing machines designed for the purpose, while at the same time these machines are fitted with a device for regulating the moisture content of the base. The good photographic properties of the system and the very low cost of materials open great prospects for its application on a large scale in all sorts of fields. In addition to the sound film and the picture-sound film also the field of micro and macro documentation is regarded as an important domain for the application of the system.

Print ISSN

0898-042X

Published

1950-03

Content type

Original Research

DOI

10.5594/J06362