Abstract

For certain applications such as the detailed analysis of field emission patterns, to obtain the current density distribution at the field cathode, complete photographic density scanning of a negative is required. The present paper describes a projection densitometer which automatically plots a function of photographic density vs position by a polar scanning of the negative in steps of two degrees or more. The resulting graphs, as well as a calibration trace obtained by a single scanning of a photographic step wedge, are recorded photographically. The instrument, which may also be operated manually, has the advantage of high resolution and can be used for the investigation of fine detail on the negative.

© 1953 Optical Society of America

Precision Densitometers for Photographic Photometry

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