Dark adaptation time for humans, after viewing a target illuminated with two different types of light sources

Abstract

The differences in scotopic recovery time between LED illuminators and a tungsten-halogen illuminator was investigated. The spectral distribution and the luminous intensity distribution of all the supplied illuminators were measured. The scotopic recovery time was measured, using a low-contrast USAF bar target and a low-level light source for background illumination. We were not able to measure a significant difference in scotopic recovery time, after the target was illuminated with the two light sources. The measured luminance levels in the laboratory are expected to differ substantially to those in the field due to the low reflectance of natural targets. Therefore, laboratory measurements should be complimented by field measurements. Our results, supported by a literature study, highlighted the necessity for further research using the current methods, as well as the validation of results by using an adaptometer.