This technical memorandum examines the spectral effects of lighting at low luminances typically found in nighttime conditions, focusing on visual performance, with brief discussions of roadway visual tasks, glare, chromatic effects, environmental effects, and others. Spectral effects that are known to occur primarily at higher levels (e.g., >5 cd/m2) are not addressed, and in most night-time environments there is enough ambient light to prevent true scotopic vision.
This document addresses several key questions: What visual performance will be produced using different light sources? and What level of lighting from the different sources is needed in order to provide equivalent visual performance or equivalent appearance of brightness? (Note that equivalent brightness does not necessarily produce equal visual performance.) This technical memorandum provides guidance for lighting practice based on visual performance at mesopic light levels.
Softcover or Digital PDF: 16 pages
Publisher: Illuminating Engineering Society (2012)
Dimensions: 8½” x 11″