this specification provides a display assembly comprising a display a light sensor module mounted proximally to said display a controller connected to said light sensor module and configured to receive an electronic signal representing a measurement of ambient light incident on said display said controller connected to said display and configured to adjust brightness of said display based on said electronic signal said light sensor module comprising a window for transmitting ambient light a light sensor for receiving said ambient light and configured to generate said electronic signal a wave guide comprising a textured surface disposed between said window and said light sensor said textured surface having a geometric structure said geometric structure configured according to a material and a thicknesses of said window said geometric structure further configured to guide ambient light travelling through said window onto said light sensor such that an intensity of ambient light that strikes said sensor varies substantially proportionally according to a function comprising a cosine of an angle of incidence of ambient light striking said window the geometric structure can be further configured such that said ambient light strikes said sensor at an angle that is substantially normal to said sensor regardless of said.