LED Flux Measurement Methods for Automotive Lighting

Currently, there is still no standardized method to measure LED flux in automotive lighting. Usually, LED manufacturers provide a lumen range (or bin) for a given type of LED. However, with the increased usage of high-flux LEDs, the need for an absolute lumen value is becoming important for optical design of automotive lamps. The knowledge of an LED lumen value is necessary for more precise lamp designs. Three different types of measurements for LED flux were compared. These three measurement methods are: 1). 2π flux integrating sphere; 2). 4π flux integrating sphere; and 3). Goniometer. In this paper, we will discuss the results from these three methods, and conclude with recommendations on the preferred methods and parameters critical for accurate LED flux measurements.