New Color Corrected Photronic Cells for Accurate Light Measurements

Some of the problems encountered in the measurement of light with Photronic photoelectric cells are discussed. A new solid glass "Visual Correction" color filter, to correct the spectral sensitivity of the Photronic cell to that of the average human eye, is described. Calculated and measured values of the relative current output of the cell, with and without the correction filter, are given for various commercial light sources. It seems probable that a cell with this new correction filter will in use, at normal incidence, be able to measure with an accuracy approaching +/- 2.0 per cent for light from tungsten lamps, +/- 5.0 per cent for all commercial monochromatic sources.