Abstract

Scotopic/photopic ratio (S/P ratio, or $R_{\mathrm{sp}}$) is an absolute measure of a light source’s performance under the mesopic vision state. However, there is more potential for a light source to reach higher mesopic performance at higher correlated color temperatures (CCTs), and these cannot be evaluated. We proposed an $R_{\mathrm{sp}}$ ratio metric to examine relative performance of the S/P ratio at a corresponding CCT. Based on examination of a large set of light sources, we established the $R_{\mathrm{sp}}$–CCT and $R_{\mathrm{sp}}$ ratio–CCT relations of different light source types. On investigating previously reported high S/P ratio light sources with the proposed metric, it shows high effectiveness in evaluating relative mesopic performance when considering CCT issues.

© 2018 Optical Society of America

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