Visual perception under tungsten lamps with enhanced blue spectrum

Abstract

An experiment was carried out to assess the visual perception of a blue-glass tungsten lamp in comparison with an ordinary tungsten lamp. The lamps were simultaneously presented in adjacent light booths to observers who were asked to balance the lights for visual equality by varying the supply voltage to the ordinary tungsten lamps. Results show that on average the observers would prefer 35.8% less illuminance from the enhanced blue sources. The performance of a visual task was maintained under the blue-glass lamps despite lower illuminance, and the majority of observers expressed preference for the luminous environment of the enhanced blue light for their workplaces. Neither V(λ) based photometry, Berman's pupil lumens, nor Lynes' photometric anomalies could account for the experimental results.