The important aspects of the optical parameters of light-emitting diodes are: luminous flux, luminous efficiency, luminous intensity, luminous intensity distribution, wavelength.

1. Light efficiency and luminous flux. Luminous efficiency is the ratio of luminous flux to electrical energy. Luminous efficiency characterizes the energy-saving characteristics of light sources and is an important indicator to measure the performance of modern light sources.
2. Luminous intensity and luminous intensity distribution. The luminous intensity of LED is to characterize its luminous intensity in a certain direction. Since the luminous intensity of LEDs varies greatly at different spatial angles, we study the luminous intensity distribution characteristics of LEDs. This parameter has great practical significance and directly affects the minimum viewing angle of the LED display device. For example, in a large-scale LED color display in a stadium, if the selected LED single tube has a narrow distribution range, the audience facing the display at a large angle will see a distorted image.
3. The wavelength for the spectral characteristics of light-emitting diodes. We mainly look at whether their monochrome lines are good, and pay attention to whether the main color LEDs such as red, yellow, blue, green, and white are pure. In many occasions, such as traffic lights, the requirements for color are more stringent.