A Comparison of Light Sources for the Petrochemical Industry

Presently, the calibration of photometers is based on the spectral sensitivity of the eye with the field of view limited to only 2 degrees. However, lighting applications of interest in work environments are rarely confined to such small fractions of the visual field. New research shows that the eye spectral sensitivity is different when a full field of view is considered. The changes in spectral sensitivity in full field are due to the influence of rod photoreceptors which have been previously and erroneously viewed as being responsive only at extremely low light levels. The rod or scotopic response has been found to be the primary spectral response of the pupil at multiple light levels, varying from typical interior levels to lower outdoor levels, such as those found in a petrochemical facility at night. In addition, scotopically rich sources impact brightness perception.