Abstract
The final aim of this study is solving a mechanism of a reduction in the visibility caused by glare sources. A physical measuring method by a single lens system is contrived in order to clarify the luminous quantities of stray light in the human eye. First, the scattering properties of a single lens system which is substituted for a human eye are measured by a photographic photometry. Secondly, a reduction in the visibility caused by glare sources are quantitatively measured by a psychophysical estimations, and "equivalent veiling luminances" are calculated based on the results. The results of above studies confirm that the luminous quantities of scattering light at a center of an image surface of an optical system can be substituted for those of stray light at a fovea in the human eye, and also a method is presented for evaluating a reduction in the visibility using the scattering properties of the single lens system when a glare source exists in the visual field.
