The design, operation and instrumental characteristics of an absolute radiometer working on the bolometric principle are described. Among the interesting features of the new absolute radiometer are its ac bridge operation involving phase sensitive detection and its operational capabilities in vacuum and at low temperatures. It can resolve irradiances of about 30 nW/sq cm at room temperature and in air with a power dissipation in the sensors due to the bridge current of only 5 mW. Drift problems due to thermal voltages are avoided without having to resort to chopping of the incident beam, making the new instrument exceptionally easy to operate. Calibrations can be performed in about the same time as is required for comparing lamps with each other on a photometric bench.
NASA STI/Recon Technical Report N
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- Research Facilities;
- Systems Engineering;
- Dynamic Characteristics;
- Mechanical Properties;
- Instrumentation and Photography