"The infrared region of the spectrum is conveniently divided into the near infrared, which extends from the red end of the visible to about 25 microns, and the far infrared, which continues to an ill-defined division point of approximately 1,000 microns. The near infrared region has been further subdivided on the basis of instrumental techniques so that the particular portion of the spectrum consisting of radiations of wave length up to 3 microns has become known as the photoelectric infrared.
Several types of detection instruments have been designed and perfected for work in the photoelectric region, but new methods and materials are constantly being sought which might give an increase in sensitivity and contribute to the simplicity of the system. Recently developed lead sulfide photoconductive cells have some of the characteristics desired. These cells respond over a region in the spectrum from about .5 micron to 3.5 microns and their high sensitivity offers the possibility of greatly increased resolving power over previous methods used. Their subminiature size is also a highly desirable physical trait in almost all cases. Some writers, who have engaged in early research on photoconductive materials, have stated that lead sulfide and similar materials have opened up a wide new field in spectroscopy. As a result of these advantages, infrared detectors utilizing them are beginning to make an appearance.
A detector using a PbS cell and designed so that it would be readily adaptable to a standard spectrometer should be or great assistance in furthering the study of the near infrared. Such a device could be used advantageously in the classroom and laboratory when familiarization with and research into the longer electromagnetic radiations is desired. With this particular type of system in mind, design and construction of the photoconductive infrared detector was attempted. To check the dependability of the completed PbS system, it was proposed to use it in extending from the visible into the near infrared region, the dispersion curve of an ordinary glass prism"--Introduction, pages 1-2.
Cleveland, E. Lynn
M.S. in Physics
Missouri School of Mines and Metallurgy
v, 29 pages
© 1951 William V. Cummings, Jr., All rights reserved.
Thesis - Open Access
Infrared detectors -- Design and construction
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Cummings, William V. Jr., "A lead sulfide near infrared detection system" (1951). Masters Theses. 4151.