Spectra of LED devices show a noticeable temperature and current dependence. Often this behaviour can be neglected. However, some applications like spectrometry or narrow band imaging take advantage of the spectral characteristics of LEDs. In such cases knowledge about the spectral behaviour is relevant. This article describes a measurement setup for investigating the influence of temperature and current on the spectral radiation of LED. Results from measurements are presented. Appropriate mathematical functions for modelling LED spectra are discussed and their applicability is rated. A new formalism for modelling of LED spectra in consideration of current and temperature is derived. With this approach, the prediction accuracy of the spectral behaviour is increased significantly.
2008 The Illuminating Engineering Institute of Japan