A light sensor module comprising: a window for transmitting ambient light, the window being characterized in terms of its material with an associated index of refraction n1, and having a particular thickness T1; a light emitter configured to emit light at a first angle; a light sensor (66, 66E) for receiving said ambient light and configured to generate an electronic signal; a wave guide including a substrate and a textured surface, the substrate being characterized in terms of its material with an associated index of refraction n2, and having a particular thickness T2, said textured surface having a geometric structure; wherein the wave guide is configured both to direct ambient light onto the light sensor and to help scatter light emitted from light emitter out of the window at an angle wider than said first angle said geometric structure further configured to guide said ambient light travelling through said window onto said light sensor (66, 66E) such that an intensity of said ambient light that strikes said light sensor (66, 66E) varies substantially proportionally according to a function; characterized by the wave guide being disposed between said window and said light sensor (66, 66E); said geometric structure comprising a plurality of trapeziums and being configured according to a material and a thickness of said window and according to a material and thickness of said substrate; and the function Y comprising a cosine of an angle (AI, AI1, AI2, θ1, θ2) of incidence of ambient light striking said window whereby Y = I cos AI where: Y is the intensity of ambient light that strikes the surface of the light sensor, I is the intensity of light that strikes the surface of the window, AI is the angle of incidence of light as it strikes the surface of the window; and wherein said wave guide is made from a material having a refractive index of between about 1.4 and about 1.7. a window for transmitting ambient light, the window being characterized in terms of its material with an associated index of refraction n1, and having a particular thickness T1; a light emitter configured to emit light at a first angle; a light sensor (66, 66E) for receiving said ambient light and configured to generate an electronic signal; a wave guide including a substrate and a textured surface, the substrate being characterized in terms of its material with an associated index of refraction n2, and having a particular thickness T2, said textured surface having a geometric structure; wherein the wave guide is configured both to direct ambient light onto the light sensor and to help scatter light emitted from light emitter out of the window at an angle wider than said first angle said geometric structure further configured to guide said ambient light travelling through said window onto said light sensor (66, 66E) such that an intensity of said ambient light that strikes said light sensor (66, 66E) varies substantially proportionally according to a function; characterized by the wave guide being disposed between said window and said light sensor (66, 66E); said geometric structure comprising a plurality of trapeziums and being configured according to a material and a thickness of said window and according to a material and thickness of said substrate; and the function Y comprising a cosine of an angle (AI, AI1, AI2, θ1, θ2) of incidence of ambient light striking said window whereby Y = I cos AI where: Y is the intensity of ambient light that strikes the surface of the light sensor, I is the intensity of light that strikes the surface of the window, AI is the angle of incidence of light as it strikes the surface of the window; and wherein said wave guide is made from a material having a refractive index of between about 1.4 and about 1.7. Y is the intensity of ambient light that strikes the surface of the light sensor, I is the intensity of light that strikes the surface of the window, AI is the angle of incidence of light as it strikes the surface of the window; and wherein said wave guide is made from a material having a refractive index of between about 1.4 and about 1.7.