Three-dimensional measurement of light-emitting diode radiation pattern: a rapid estimation

We describe a simple imaging technique that enables a three-dimensional inspection of the angular intensity distribution of a light-emitting diode (LED) over a significant part of the hemisphere. The measurement set-up is very simple: it consists of only a charge-coupled device (CCD) camera and a flat diffuse translucent screen. An LED illuminates the screen, and the CCD camera records one image from the back. The visualization algorithm takes into account the cosine-fourth law, vignetting and screen transmittance to render the far-field radiation pattern from the recorded image