Estimate luminance of single panel and dual panel light guide by luminous flux flow

Abstract

This paper presents a mathematical method to estimate luminous flux and luminance of single panel and dual panel light guides based on photometric calculations under various design requirements. The distribution of dot pattern or micro-prism was computed according to those estimated luminous flux on the illuminant surface. The effects of light source efficiency, angular distribution of luminance of light guide, luminous flux ratio and area ratio of main panel with sub panel on luminance of light guide are discussed. The relationship between luminous flux and luminance was derived for single panel and dual panel light guides. For single panel light guide, the result reveals that the angular distribution of luminance of light guide affects the luminance obviously. The luminance increases as the cone angle (the range of angular distribution of luminance) decreases. For dual panel light guide, the luminous flux of three different areas, two located at main panel and one located at sub panel, are the functions of angular distribution, luminous flux ratio and area ratio. The luminance of main panel and sub panel were estimated and computed from mathematical functions. The optical properties of dot pattern and micro prism or other optical objects were used to determine the luminous flux ratio and then the difference luminance between main panel and sub panel was estimated. This estimation strategy provides a fast initial design and the solution to predict the luminance of single panel and dual panel of light guide.