Radiation Pattern Measurement in the Planar Coordinate

A planar measurement approach is presented to obtain the radiation pattern, by which rotation operations can be removed or reduced for a source with narrow and divergent viewing angle, respectively. The Étendue conservation is applied to derive the intensity distribution relationship between planar and spherical surfaces, which is further used for the radiation feature measurement on planar systems. As an indirect approach, sampling position distribution and measurement sensitivity is then discussed. Four application scenarios of the method are proposed and experimentally studied, including: 1D, 3D wireframe, pattern reconstruction for Monte Carlo ray-tracing planar data and 3D pattern estimation for luminaires. 1D radiation pattern obtained by classical goniophotometer method is employed as an evaluation standard, and experiments indicate that the results agree well between the two approaches. Therefore, the planar measurement can be applied as an alternative or supplementary method of the goniophotometer to test angle-dependent attributes of sources.