Flux Averaging Devices for the Infrared.
NATIONAL BUREAU OF STANDARDS GAITHERSBURG MD
Pagination or Media Count:
The spatial and angular sensitivity of infrared detectors recently has been investigated. In order to eliminate this effect and obtain accurate measurements in the infrared, it is necessary to distribute the flux as uniformly as possible over the entire sensitive area of the detector. A solution to this problem is presented in the form of several averaging devices developed at the National Bureau of Standards. Among the devices investigated are roughened NaCl windows, diffusing light ducts, and spheres with different coatings. Each device was subjected to a series of tests to establish its averaging capability and useful wavelength range. Results of these tests indicate that the use of a small sulfur coated hollow sphere over the detector increased the accuracy of most types of infrared reflectance measurements and, at the same time, decreased the requirement for precise optical alignment of the detector in the wavelength range of 1.5 to 8 microns. The use of the sulfur coated sphere over a thermopile extends the usefulness of the multiple-reflection specular reflectometer to about 10 microns.
- Infrared Detection and Detectors