Ensuring accuracy in optical and electrical measurement of ultra-bright LEDs during reliability test

In order to accurately estimate the lifetime of Light Emitting Diodes (LEDs), accelerated stress tests have to be performed, and measurements done throughout the tests should be free of artifact and repeatable to ensure accurate observations of the degradation of the LEDs. In this work, measurements artifact arising from DC biasing and PWM settings were first presented. Electrical measurements consistency was then studied. Optimized setting for accurate measurement is obtained using Response Surface Method with Central Composite Design, and the setting is verified through experiments.