Why does LED light test luminous flux need an integrating sphere? How is the integrating sphere test

Why does LED light test luminous flux need an integrating sphere? How is the integrating sphere tested?

The integrating sphere is a cavity sphere whose inner wall is coated with white diffuse reflective material, also known as photometric sphere, luminous flux sphere, etc. One or several window holes are opened on the spherical wall, which are used as light inlet holes and receiving holes for placing light receiving devices. The inner wall of the integrating sphere should be a good spherical surface, and it is generally required that its deviation from the ideal spherical surface should not be greater than 0.2% of the inner diameter. The inner wall of the sphere is coated with an ideal diffuse reflection material, that is, a material with a diffuse reflection coefficient close to 1.

The working principle of the integrating sphere is:

The light is collected by the integrating sphere through the sampling port as shown in the figure below. After multiple reflections inside the integrating sphere, the light will exist very uniformly at various positions inside the integrating sphere. When using the light in the integrating sphere to measure, we can measure The result is more reliable. The advantage of using the integrating sphere structure is that it can reduce and eliminate the measurement error caused by the shape of the light, the angle of divergence, and the difference in the responsivity of different positions on the detector. How does the integrating sphere measure LED light?

1. Preparation: Prepare an integrating sphere of suitable size, a standard light source with a luminous flux close to the light source of the lamp, and an ambient temperature of about 25 degrees to avoid wind blowing into the integrating sphere;

2. Inspection: Install the standard light source into the integrating sphere, connect the current source and power meter, and then light the standard light source. In the integrating sphere software operation interface, adjust to continuous test, until the luminous flux reaches stability, record its luminous flux value;

3. Calibration: The operation of calibration is similar to that of checking, the difference is that zero calibration is performed before lighting the standard light source. After the luminous flux is stable, input the standard color temperature and standard luminous flux of the standard light source in the integrating sphere software operation interface, and then click to start calibration, the integrating sphere tester will automatically complete the calibration;

4. Test the sample: Install the sample into the integrating sphere, light the sample, close the integrating sphere, and start the test. After the luminous flux is stable, record the value.

HOPOOCOLOR recommends a series of products as follows:
HPCS6500 Newest model system
HP8000 Traditional model system
OHSP350A/OHSP350M portable model system

Hangzhou Hopoo Light&Color Technology Co., Ltd. focuses on the production, research and development and sales of lighting and electrical testing instruments. The whole series of products are developed and produced in strict accordance with the requirements of ISO9001:2015; all products meet the requirements of CIE; in addition, All products of hopoocolor have passed CE certification and obtained the qualification to export to the European Union. The main products include goniophotometer, integrating sphere, spectroradiometer, illuminometer, colorimeter, and LED test instruments. 

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