Computer aided design method to predict luminous intensity distribution of luminaire

The properities of reflection on a surface involve both regular and diffuse reflections. This property is approximated with the equation, Y=(1-sin X)α, where Y is the relative luminous intensity and X is a function of light incident angle to the surface. Luminous intensity distribution for some luminaires are predicted by using a computer aided design method, based on this equation. α is the specularity factor, which represents the degree of surface specularity. It is about 0.4∼1.0 for white painted plates and 2∼10 for semi-diffused aluminium plates, as determined as a result of experiments using three plate reflectors with tungsten halogen lamp. It was found through many experiments and calculations that the results predicting the luminous intensity distribution of a luminaire which consists of a three plate reflectors and a fluorescent lamp approximately conformed to practical use.