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Abstract
An E.M.3 Metropolitan Vickers electron microscope was modified to enable the accelerating voltage and the current density falling on the photographic plate to be measured. This modified instrument was then used to investigate the response of a series of photographic materials, with accelerating voltages of 25 to 78kV. and current densities of 10-11 to 2x 10-10 amp/sq.cm. Exposure times were in the range of 0.05 to 4.5 sec. The ratio of the speeds of the fastest to the slowest emulsion varied between 20:1 and 50:1 depending on the kilovoltage. For Nuclear Research B2 plates the D/E curve was linear over a wide range of densities and the photographic effect could be described by a simple linear equation connecting density, kilovoltage and exposure. Two of the other emulsions, Rapid Process Experimental and Thin Film Half Tone, also showed a linear D/E relationship near the origin. The slope of the linear portion of the Rapid Process Experimental curves was proportional to the accelerating voltage, but that of Thin Film Half Tone was not, possibly due to the loss of electrons from the rear of the emulsion. Photomechanical and Contact Lantern, the slowest materials, had “S” shaped D/E curves indicating the possibility of reciprocity failure.