How to use the LISUN integrating sphere for LED light measurements

Integrating sphere, also known as luminous sphere and photometric sphere, is a hollow and complete spherical shell.
The integrating sphere is mostly made of metal materials, and the inner wall is coated with a white high diffuse reflection layer (usually magnesium oxide or barium sulfate), and all points on the inner wall of the sphere diffuse evenly. There are also integrating spheres made of highly reflective polymer data, such as Spectralon data. The illuminance of the light source at any point on the spherical wall is the superposition of the illuminance of the repeatedly reflected light In this way, the light entering the integrating sphere is repeatedly reflected by the inner wall coating to form a uniform illumination on the inner wall.

The integrating sphere is often used to measure the luminous flux, color temperature, luminous efficiency and other parameters of a light source. It can also be used to measure the reflectivity and transmittance of an object.

The working principle of the integrating sphere:
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 in all positions inside the integrating sphere very evenly When we use the light in the integrating sphere to measure, we can make our measurement results 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 divergence angle, and the difference in the responsiveness of different positions on the detector.

Working conditions of ideal integrating sphere (internal design of integrating sphere):
1. The inner surface of the integrating sphere is a complete geometric sphere with equal and smooth radius everywhere;
2. The inner wall of the integrating sphere is coated with a coating with high reflectivity, which is a neutral uniform diffuse surface with the same diffuse reflectance for incident light of various wavelengths;
3. The interior of the sphere is regarded as an abstract light source that only emits light without any real object.

During the integrating sphere test, according to the different types of light sources, the installation positions for installing the light sources during the test are also different. LISUN has used integrating sphere 4 π and 2 π test methods:

Integrating sphere 4 π measurement method: the tested light source is installed in the center of the integrating sphere, so that the light is emitted to all sides With this measurement method, the sample installation is simple and the time for changing the sample is short, but the influence of self absorption effect should be considered.
Integrating sphere 2 π measurement method: the measured light source is installed on the opening of the spherical wall at the side of the integrating sphere to let the light enter the integrating sphere from the outside This measurement method does not need to consider the effect of self absorption, but needs to be equipped with an aperture reduction device to adapt to different sizes of samples.

Due to install of the tested object more convenient and the test more accurate, LISUN through continuous efforts to improve, has developed an integrating ball, which is formed by a machine at one time, so that the inner wall of the ball is smooth and the reflection effect is good; And the inside of the integrating sphere is equipped with a platform with adjustable up and down directions (it is very convenient to install the tested lamp, and the maximum load is 30kg); One more, humanized is that the integrating sphere is also equipped with a cross laser (the installation position of the standard lamp / tested lamp can be calibrated to ensure that it is installed at the center of the sphere)

Therefore, LISUN launched LPCE-2 Integrating Sphere Spectroradiometer LED Testing System is for single LEDs and LED lighting products light measurement. LED’s quality should be tested by checking its photometric, colorimetric and electrical parameters. According to CIE 177, CIE84,  CIE-13.3, IES LM-79-19, Optical-Engineering-49-3-033602, COMMISSION DELEGATED REGULATION (EU) 2019/2015, IESNA LM-63-2 and ANSI-C78.377, it recommends to using an array spectroradiometer with an integrating sphere to test SSL products. The LPCE-2 system is applied with LMS-9000C High Precision CCD Spectroradiometer or LMS-9500C Scientific Grade CCD Spectroradiometer, and A molding integrating sphere with holder base. This sphere is more round and the test result is more accruacy than the traditional integrating sphere.

LPCE-2(LMS-9000)
High Precision Spectroradiometer Integrating Sphere System

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

Our main products are Goniophotometer, Integrating Sphere, Spectroradiometer, Surge Generator, ESD Simulator Guns, EMI Receiver, EMC Test Equipment, Electrical Safety Tester, Environmental Chamber, Temperature Chamber, Climate Chamber, Thermal Chamber, Salt Spray Test, Dust Test Chamber, Waterproof Test, RoHS Test (EDXRF), Glow Wire Test and Needle Flame Test.

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