Measurement requirements for LED testing

摘要

The photometric measurement of LEDs can be more of an art than an exact science. There are various geometric, electrical, and assembly issues that can greatly affect the optical properties of LEDs. Because no two LEDs are exactly alike, there are steps that must be taken to enhance the accuracy of device measurements. These steps are explained in the following paragraphs: The LED's mechanical center may not be its optical center. When placing an LED into a typical test fixture, it is natural to assume the light is emanating from the device's mechanical center. This is frequently not the case (see Fig. 1).