Luminance measurement of curved surface sources

As they are light, thin, rollable, break-resistant, and have fewer limitations on space, flexible components, especially flexible displays, are highly attractive for next generation electronic products. Curved is the most common shape for current flexible products. Two methods for measuring the luminance distribution of curved surface sources are investigated in this paper, including the theoretical analysis, numerical simulation, experiment and uncertainty analysis. The luminance measurement results of flexible sources not only depend on the photometric characteristics of the sources themselves, but also depend on the measurement method, such as the setting of the measuring instrument and the measurement position. The results of numerical simulation show that the more the source is unlike a Lambertian source or the smaller the curvature of the source, the greater the effect of the measurement method on the measurement results. Theoretically, the luminance distribution from one measurement method can be estimated from the other method by multiplying by conversion factors. An experiment is performed to verify the possibility of converting and also verify the correction of the theoretical analysis. For precise luminance measurement, position alignment is the key factor to reduce the uncertainty. Unlike with flat surface sources, the luminance measurement result for a curved surface source is strongly dependent on the measurement conditions. The currently documented standards for evaluating the optical performance of a flat surface source may not be appropriate for a flexible surface source. It is necessary to refine a new measurement provision to help the manufacturers utilize the appropriate metrology.