Assessment of Some Mechanisms for Near IR Narrow Pass-Band Filters.
STANFORD RESEARCH INST MENLO PARK CALIF
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Two types of novel physical systems are examined as possible IR filters. To observe a small, hot CO2 source against a cooler but strong background of CO2 emission, the background must be exceedingly uniform. An optically thick filter of CO2 can turn a variable background into a uniform one, while still transmitting the hot signal at high rotational lines. At the IR absorption edge of semiconductors, the index of refraction could theoretically for the proper materials exhibit abrupt variations with wavelength. If a material had a specified index of refraction only within a narrow wavelength band, it could serve as an effective filter for that band. Examination of the qualities of real semiconductors does not, however, hold promise for their use in developing finely tuned adjustable filters. Author
- Infrared Detection and Detectors
- Solid State Physics