ABSTRACT
This chapter explains the realization of blackbody sources and the basic elements of radiometric computations. Blackbody sources are primarily used as calibration sources and have and continue to be the subject of intense research. The two basic types of experimental blackbody sources are the cavity type and the flat plate type. Cavity type blackbody sources are very common and provide excellent performance. Cavity type blackbody sources are limited by the physical size of the source and output aperture diameter, which make them impractical to use for applications needing large area sources. Cavity geometry can also significantly impact the radiometric behavior of a blackbody source, as can the cavity surface "roughness." The inverse square law is of fundamental importance in electromagnetic propagation and plays an important role in radiometry, radar, lidar, and antennas. In discussing the emission of radiation from a source, measurements related to angles play an important role.
