Spectral discomfort glare sensitivity investigations.

The main concern of car headlamp manufacturers is to provide better visibility. Unfortunately by increasing the luminous intensity of the headlamp the risk of increasing discomfort glare for the other road users increases. One possibility to increase visibility and decrease glare could be the selection of a spectral power distribution for the headlamp such that it emits in wavelength regions (if such wavelengths exist) where luminous sensitivity is high, and glare sensitivity is low. For this the spectral discomfort glare sensitivity of humans under low photopic conditions has to be determined. Spectral discomfort glare sensitivity was determined using ten young observers, requesting the observers to select medium glare settings of monochromatic radiations based on the de Boer glare rating scale, both at near-foveal and 10° extra-foveal directions of the 2° diameter glare source. It was found that the spectral discomfort glare sensitivity function could not be described by a simple addition of the photopic spectral luminous efficiency function and the short wavelength cone fundamental, but that the contribution of the chromatic channels of human vision may also have to be considered. [ABSTRACT FROM AUTHOR]