Abstract

A method is described for measuring automatically the spectral energy distribution of luminescent materials or of other light sources. A photo-multiplier operated on d.c. is used with a standard constant deviation spectrometer for measuring the energy in the spectrum. A compensator has been built in the spectrometer so that the output of the photo-cell is proportional to incident energy of any wave-length. A drive mechanism sweeps the spectrum across the exit slit at constant wave-length rate, and the photo-cell output appears on the chart of a standard photoelectric recorder. Errors, due chiefly to inaccuracies in milling the compensator, are less than 5 percent except in the extreme violet. Curves repeat within 1 or 2 percent. Spectral curves can be taken of surfaces whose brightness is as low as 1 foot lambert. The time to obtain a distribution curve may be varied from one-half to two minutes by a change of gears.

© 1948 Optical Society of America

A Method for Measuring the Spectral Energy Distribution of Low Brightness Light Sources

Frank J. Studer
J. Opt. Soc. Am. 37(4) 288-291 (1947)

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The Effect of Spectral Quality of Light on Visual Performance and Fatigue*

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