A scanning spectroradiometer.

Abstract

An instrument is described by which the absolute spectral power distribution of light sources can be displayed directly on a pen-recorder. It is based on a grating monochromator which is motor driven at a scanning rate of 100 nm min−1, and the variation with wavelength of the overall instrument response is automatically compensated by an electrical attenuator network connected to a multitapped potentiometer geared to the wavelength drive. The use of a diffusing screen for the entrance optics makes the output independent of source geometry, and allows an absolute scale calibration, with an error not exceeding 10%, to be obtained by means of a standard tungsten lamp.