Based on the Goniophotometer: luminous intensity measurement and ies testing

Lighting fixtures play a crucial role in the field of lighting. To ensure the lighting effect and quality of the fixtures, it is necessary to test and evaluate their light intensity distribution. This article will introduce the methods and steps of using a Goniophotometer for luminous intensity measurement and ies testing.
A goniophotometer is the main measuring device for testing the photometric performance of lighting fixtures. It can be used to measure parameters such as the spatial light intensity distribution, total luminous flux, and luminaire efficiency. The components of a goniophotometer system include a precision turntable and control system, spectral analysis system, standard lamp, alignment system, and computer processing system.

A goniophotometer requires the use of a large dark room, with low reflectivity materials to prevent stray light from entering the probe. Due to its sensitivity to environmental temperature, it is crucial to maintain the stability of the light source’s temperature. The goniophotometer reads the measurements one angle at a time, which can be time-consuming. If only the luminous flux parameters of the luminaire need to be measured, there are no strict requirements for the measurement distance.

According to different arrangements of the measurement light path, there are two measurement methods for measuring light flux: the illuminance integration method and the light intensity integration method.
1. Illuminance integration method. There is no restriction on the measurement distance, and a small measurement space is required. As long as the illuminance can be measured, even if the distance is very short, an accurate total light flux can be obtained. The compact photometer can be used to measure the illuminance distribution of the light source in space and integrate it over the entire space to obtain the total light flux. It is insensitive to the measurement distance and the installation position of the light source, and can avoid the use of mirrors, thereby achieving high measurement accuracy. It is a method recommended by the CIE for the implementation of the standard unit of light flux.

2. Light intensity integration method. The light intensity integration method measures the light intensity distribution of the light source in space and integrates it over the entire space to obtain the total light flux. Sufficient distance is required to measure the light intensity distribution and approximate the measured object as a point light source, using the inverse square relationship for distance to measure the light intensity.

The vertical distributed photometer is a commonly used testing instrument for measuring the light intensity distribution of fixtures. It usually consists of a measurement probe, a sphere, a photodiode, and other components. During the testing process, the measurement probe is placed at a certain height and distance to receive the light radiation emitted by the fixture. Then, based on different measurement methods and requirements, the direction can be measured. By measuring at different angles and distances, the light intensity data of the fixture in different directions can be obtained.

Before conducting the test, the testing instrument needs to be calibrated. The purpose of calibration is to ensure the accuracy and stability of the testing instrument. During the calibration process, it is necessary to calibrate based on a standard light source and record the calibration parameters.

Once the calibration is completed, the testing of the light intensity distribution of the fixtures can begin. During the test, the vertical distributed photometer is placed at the predetermined distance and height and aligned with the center of the fixture. Then, different measurement angles and ranges can be selected according to the requirements. By plotting the curve of light intensity versus angle, the light intensity distribution of the fixture in different directions can be visually understood. Additionally, metrics such as average, maximum, and minimum light intensity can be calculated to evaluate the lighting effect and uniformity of the fixture.

In addition to the light intensity distribution test, IES testing is also an important method for evaluating the quality of fixtures. IES (Illuminating Engineering Society) is a standard format established by the international society of lighting engineers for describing the photometric performance of fixtures. The IES file contains information about the light intensity distribution, color parameters, power factor, etc., of the fixture, providing detailed and comprehensive performance data.

During IES testing, the fixture needs to be installed in a specific testing setup and connected to the power supply and control system. Then, using the corresponding testing software or equipment, the light intensity distribution of the fixture is tested. By analyzing the data in the IES file, information such as light intensity distribution, color parameters, and power factor of the fixture can be understood. The light intensity distribution can be shown through illuminance maps or intensity distribution diagrams to visually understand the lighting effect and uniformity of the fixture. Color parameters, such as color temperature and color rendering index, can be used to determine the color quality of the fixture. Power factor represents the electrical energy utilization of the fixture and can be used to evaluate its energy efficiency performance.

In conclusion, the testing of light intensity distribution and IES testing using a vertical distributed photometer are important methods for evaluating the quality of fixtures. Through the measurement and analysis of light intensity in different directions, the lighting effect and uniformity of the fixture can be understood. IES testing provides comprehensive and detailed performance data of the fixture. These testing methods can assist lighting designers and manufacturers in selecting suitable fixtures and ensuring their lighting effect and quality meet the expected requirements.

In practical applications, it is recommended to choose suitable testing environments and equipment when conducting light intensity distribution testing and IES testing. The testing environment should simulate the actual usage scenarios as much as possible to ensure the accuracy and reliability of the test results. Additionally, regular calibration of the testing instrument is important to ensure the accuracy and reliability of the test. By conducting testing and evaluation in a proper manner, fixtures that meet the requirements and provide high-quality lighting can be selected.

What is the definition of type C goniophotometer?

LSG-6000 Moving Detector Goniophotometer (Mirror Type C) was manufactured by LISUN completely meets LM-79-19, IES LM-80-08, COMMISSION DELEGATED REGULATION (EU) 2019/2015, CIE-121, CIE S025, SASO 2902, IS16106 and EN13032-1 clause 6.1.1.3 type 4 requirements. LSG-6000 is the latest upgraded product of LSG-5000 and LSG-3000 in compliance with the requirements of the LM-79-19 standard Clause 7.3.1, its an automatic light distribution intensity 3D curve testing system for measuring light. The darkroom can be designed according to the customer’s existing room size.

LM-79 Moving Detector Goniophotometer (Mirror Type C) 

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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