Road Lighting Design from the Point of View of Mesopic Vision(<Special Issue>Efficient and Safe Lighting Based on the Spectral Sensitivity of Human Vision at Mesopic Light Levels)

Abstract

In recent years, LED has become widespread in the world as light sources for outdoor lighting. Replacing existing light sources to LED, the energy consumption is greatly reduced. From CIE191 and other studies, under low light(mesopic) conditions, people can see brighter and more quickly detect objects which are illuminated by the lamp which has more shortwavelength components. However, this is the effect in peripheral vision, The most important light coming from the viewed object activates the very center of the retina known as the fovea. The rod response does not contribute to the important visual task of direct object recognition. Therefore, (1) the recommended light levels should be specified standard photopic photometric quantities and (2) the lamp which has more shortwavelength components is effective under mesopic lighting conditions for outdoor lighting such as a pedestrian in a roadway. In this paper, discuss technical challenges to mesopic vision technology into outdoor lighting.