Spatial-angular luminance distribution measurement of phosphor-based LEDs

The measurement of the spatial-angular luminance distribution of a light source is absolutely required to fully describe the emission characteristic of the light source. Today, these measurements are used for generating ray data (“ray files”), which are commonly employed for optical simulation tools (ASAP, Zemax, etc.) for the design of modern luminaries, e.g. SSL-lamps which use light-emitting diodes (LEDs) as light sources. Additionally, in order to optimize the optical design of the SSL- sources, the luminance distribution as a function of the wavelength of the light source is also required. In this conference, the investigation of the angular luminance distribution of the high-power phosphor-based white LED is presented. The luminance distribution is measured with a near-field goniophotometer established at PTB based on an Imaging Luminance Measurement Device (ILMD) as a detector. Moreover, the investigation of the wavelength dependence of the angular luminance distribution, measured by separating the “blue” and “yellow” components of the light emission of the LED by means of a band-pass and a long-pass filter, is also presented.