Differences between Goniophotometer and Integrating Sphere for Solid State Lighting Products Test

Solid-state lighting includes LED and OLED. With the elimination of incandescent lamps and the gradual withdrawal of high-pressure mercury lamps, the scope of traditional lighting has narrowed, and currently mainly includes light sources such as halogen tungsten lamps, fluorescent lamps, high-pressure sodium lamps and metal halide lamps, as well as their supporting electrical appliances and lamps. LED does not contain harmful luminescent substances such as mercury, and its luminous efficiency, life and luminous flux maintenance rate all exceed traditional light sources, so its advantages in energy saving and environmental protection have been recognized by everyone. Therefore, LED lamps are widely used, and detection of LED lamps Demand is also increasing. There are professional integrating spheres for measuring the luminous flux and chromaticity parameters of light sources and goniophotometers for measuring angle-related characteristics of LED and solid-state lighting products.

How a Goniophotometer Works
The Goniophotometer is the main measurement equipment for the light distribution performance test of lamps. It can be used to measure the spatial light intensity distribution, total luminous flux and lamp efficiency of lamps or light sources. The system components of the goniophotometer include: precision turntable and control system, standard lamp, alignment system and other parts. The goniophotometer needs to be used with a larger dark room. 

Goniophotometer test method
1. The double-column structure (B-β and A-α plane coordinate systems) is mainly used for measuring floodlights, etc. When installing the lamp, make the light-emitting center of the lamp consistent with the rotation center of the rotary table. In the B-beta coordinate system, the luminaire axis coincides with the horizontal axis of the rotary table. In the A-α coordinate system, the luminaire axis is perpendicular to the horizontal axis of the rotary table.
2. The single-column structure (C-γ plane coordinate system and conical coordinate system) is mainly used to measure lamps such as downlights and grille lights. When installing the lamp, make the light-emitting center of the lamp consistent with the rotation center of the rotary table. The optical axis of the luminaire coincides with the horizontal axis of the rotary table.

The basic principle of the integrating sphere :
The light is collected by the integrating sphere through the sampling port, and after multiple reflections inside the integrating sphere, it is scattered very uniformly inside the integrating sphere. When the integrating sphere is used to measure the luminous flux, the measurement results can be made more reliable, and the integrating sphere can reduce and remove the Measurement errors caused by the shape of the light, the angle of divergence, and the difference in responsivity at different positions on the detector.

Measuring principle of integrating sphere:
In the process of light source testing, the main function of the integrating sphere is to use as a light collector, which is an important component of the photometric system. The integrating sphere is a hollow sphere. Spray the reflective paint. Since the energy band gap of the coating material on the inner wall of the integrating sphere is very high, it hardly absorbs light energy, so there is no light loss. When the light source to be measured is installed at the center of the integrating sphere, the light passes through the sphere for a long time. After secondary reflection and diffuse reflection, it is evenly distributed on the inner wall of the sphere. By measuring the light energy of a small area of the inner wall of the integrating sphere, the total light energy emitted by the light source can be calculated. , the integrating sphere measurement system is divided into two types: integrating sphere photometer measurement system and integrating sphere spectral analysis system. The former uses a photometric probe as a detector and cooperates with a photometer to measure optical parameters; the latter uses an optical fiber to collect light from the sphere wall, and cooperate with Spectrometer to measure parameters such as photometric, chromatic and radiometric.

Two test methods for integrating sphere 4π and integrating sphere 2π
1. Integrating sphere 4π measurement method: The light source to be tested is installed in the center of the integrating sphere, and the light is emitted around. When this measurement method is used, the sample installation is simple, and the time to replace the sample is also short, but the influence of the self-absorption effect needs to be considered .
2. Integrating sphere 2π measurement method: The light source to be measured is installed on the opening of the spherical wall on the side of the integrating sphere, allowing the light to enter the integrating sphere from the outside. This measurement method does not need to consider the influence of the self-absorption effect, but needs to be equipped with an aperture reduction device to adapt to the Samples of different sizes.

The measurement of photometric performance parameters of LED lighting products can be measured by a goniophotometer or an integrating sphere system, or it can be used in combination. Which method to choose depends on the light characteristics to be measured, product size and other requirements. The integrating sphere system of the lamp is suitable for measuring the light characteristics parameters of integrated LED lamps and relatively small size LED lamps. The advantages of integrating sphere system testing are that the measurement is fast and does not require a dark room. The goniophotometer provides the light intensity distribution and total luminous flux Measurement method, it can measure relatively large LED lighting products. Pay attention to the test environment requirements, air flow may affect the measurement of more temperature-sensitive LED lighting products. Use the goniophotometer method to pay attention to the correct clamping positioning. The high-precision spectral radiation on the meter is the direct measurement of the spatial distribution of light intensity without mirror reflection. Compared with integrating spheres, it is time-consuming to use a goniophotometer to measure. Under the premise of correct test methods, accurate detection methods can be selected reasonably. Measure the photometric performance parameters of LED lighting products to provide data support for scientific evaluation of LED lighting product performance quality status and development trends.

Therefore, Hangzhou Hopoo Light&Color launched HPG2000 rotating probe vertical goniophotometer (full space goniophotometer), which fully meets the requirements of LM-79-19, EN13032-1, type 4 of goniophotometer, CIE S025, SASO2902, IS16106 and GB and other requirements for optical parameter testing. HPG1900 and HPG1800 horizontal goniophotometers can automatically test the 3D system of the light intensity distribution curve. The test distance varies from 5 to 30 meters, which can meet the test requirements of various light sources, such as LED light sources, plant lighting, HID light sources, Various lighting fixtures such as indoor and outdoor lighting, street lights and floodlights.

Measurement parameters:
Light Intensity, Light Intensity Distribution, Area Luminous Flux, Luminous Efficiency, Luminance Distribution, Utilization Coefficient, Luminance Limit Curve, Glare Level, Maximum Permissible Distance-to-Height Ratio, Isoilluminance Diagram, Upward Luminous Flux, Downward Luminous Flux, Equal Luminance Curve, Equal Luminance Strong curve, effective luminous angle, EEI, UGR, etc.

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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