The application of a non silver Halide process (Kalfax) to air photography
Coleman, David B Jr
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The purpose of this study is to investigate the sensitometric properties of a new non-silver halide photographic process called Kalfax. Development of this material is completely dry; it requires only applied heat. Special attention is focused on the Kalfax materials in regard to future military reconnaissance requirements of rapid in-flight processing and photographic materials that are immune to nuclear radiation. The Kalfax materials exhibit properties that fill many of these requirements. The information obtained from this investigation can be utilized for other applications where there is a need for a fast dry photographic process. A brief discussion of the Kalfax process is given to familiarize the reader with the light scattering technique to obtain optical density. The mechanics of using a photosensitive material in a polymeric vehicle to obtain the light scattering centers are explained. The striking differences between the nature of the Kalfax image and conventional silver image are discussed to enable understanding of different processes. The experimental procedure is outlined. A description of the equipment used for processing includes the sensitometer (exposing device) and the developer unit. Data is given for the ultraviolet sources used in the special sensitometers. The various types of heat sources that are useful for developing are examined. Several problems encountered in preliminary tests are described and analyzed. The major portion of this thesis is devoted to a detailed analysis of the photographic behavior of the Kalfax materials. The characteristic curves are given for the papers and films. A comparison is made between the high and low contrast Kalfax emulsions. Sepsitometric quantities such as fog, gamma, relative speed, maximum density and exposure range are given for each material. Printing densities, as well as, ultra violet densities are measured for the films. The true specular densities were determined in addition to the diffuse densities so the Callier factors could be computed. Because of the unusual photosensitive process employed in forming an image with the Kalfax materials, speed shifts are encountered for long exposure times. An explanation of this effect in terms of diffusion properties is given along with the characteristic curves which show these effects. Other exposure effects such as reciprocity failure, development delay and clearing times are examined. A series of tests to determine the effect of pre- and post-sensitization are described and analyzed in regard to speed changes. The effects of varying the development temperature are discussed briefly. A comparison of the Kalfax materials with conventional silver halide materials is made. The Kalfax films are compared with Micro-File under the identical exposure conditions. The Micro-File was 2.2 x 10^5 times faster than Kalfax film type 94 (high contrast). Kodak Azo printing paper is compared with Kalfax printing paper under the same exposure conditions and found to be 2.88 x 10^4 times faster. The Kalfax materials are lacking in sensitivity but they can be completely processed in dry form in a matter of minutes in a normally illuminated room. This is one of the advantages to be considered in these materials. The use of Kalfax materials in aerial photography is limited at the present time because of the low sensitivity. Considerable theoretical and experimental work is required in order to realize the potential of the Kalfax materials. There is however, a definite use for the Kalfax materials in the reproduction field. An example of the use of Kalfax paper for reproduction is shown with an aerial photograph printed on Kalfax low contrast paper from an aerial positive of scale 1:20,000.
Thesis (M.A.)--Boston University
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