In many instances, a radiometer’s responses are found to be nonuniform with respect to target positions within its field of view. This paper examines the effects of spatial nonuniformity for the case of a symmetrical uniform source boresighted in the radiometer’s field of view and shows how these effects can be dealt with by relating the radiometer’s output with its field of view unfilled to its output when its field of view is totally filled by a uniform source. By analysis of a Huggins Mark IX radiometer, it is shown that errors in excess of 18% can result through ignorance of the radiometer’s nonlinearity caused by spatial response nonuniformity.
F. A. Reed, "Methods of Determining the Spatial Response Nonlinearities of Radiometers," Appl. Opt. 9, 2130-2130 (1970)