Light-emitting-diode inspection using a flatbed scanner

There is a need to ensure that light-emitting diodes (LEDs) are performing well as they are increasingly used in demanding applications. In this work, we present an adapted usage of flatbed scanners to inspect LEDs. This offers the benefits of lower cost and higher measurement throughput than specialized equipment like goniophotometers. The technique is demonstrated to detect LED encapsulation defects, to identify low illumination and misaligned LEDs in arrays, and to evaluate angular color nonuniformity of white LEDs. (C) 2008 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.2995991]