Understanding How Light Intensity is Measured in Full-Space Distribution Photometers Using the LISUN LSG-6000 LM-79 Moving Detector Goniophotometer
Abstract
Light intensity, a key parameter in lighting design and testing, plays a significant role in the development of lighting products that meet international standards such as LM-79. The LISUN LSG-6000 LM-79 Moving Detector Goniophotometer (Mirror Type C) is an advanced instrument that provides precise measurement of light intensity distribution in three-dimensional space. This paper discusses the principles of measuring light intensity, the significance of LM-79 standards, and provides detailed insights into how light intensity is measured in goniophotometers like the LISUN LSG-6000. The paper also presents experimental data, supported by tables and figures, illustrating the capabilities of the LSG-6000 in evaluating light sources.
1. Introduction
Light intensity is measured in candelas (cd), which quantify the luminous intensity emitted by a light source in a specific direction. Accurate measurement of light intensity is crucial for lighting manufacturers, particularly in assessing compliance with photometric standards like LM-79, which defines uniform testing conditions for LED lighting products.
The LISUN LSG-6000 LM-79 Moving Detector Goniophotometer, based on a mirror Type C design, allows for comprehensive analysis of a light source’s luminous intensity distribution. This device is widely used in industries such as lighting manufacturing and quality control due to its ability to provide precise measurements. In this paper, we explore how light intensity is measured in this goniophotometer, focusing on the underlying principles, the measurement process, and data presentation.
2. Principles of Light Intensity Measurement
The primary purpose of light intensity measurement is to quantify how light is distributed across different angles around the source. The goniophotometer does this by rotating the light source and recording the intensity in all directions. The unit of measurement is the candela (cd), representing the luminous intensity in a given direction.
Instruments like the LISUN LSG-6000 follow the Type C goniometric system, in which light intensity is measured in a horizontal plane as the device rotates around the light source. This method ensures a full-space distribution of light intensity data, necessary for evaluating how light will perform in real-world applications.
3. The LM-79 Standard and Its Importance
LM-79 is a standard developed by the Illuminating Engineering Society (IES) to ensure that LED lighting products are tested in a uniform and reproducible manner. The standard outlines methods for testing photometric and electrical properties, including luminous flux, color, and electrical power.
The LISUN LSG-6000 goniophotometer is compliant with LM-79, enabling manufacturers to measure light intensity and distribution according to these global standards. Meeting LM-79 certification is often a prerequisite for LED lighting products to enter certain markets, particularly in the United States and Europe.
4. Overview of the LISUN LSG-6000 LM-79 Moving Detector Goniophotometer
The LISUN LSG-6000 is designed to measure the spatial distribution of light intensity in all directions, providing accurate 3D models of the light output. It achieves this by rotating the light source and mirror in precise steps, allowing for measurement across a wide angular range. The key features of the LSG-6000 include:
• Measurement Range: 0.001 cd to 30,000,000 cd
• Accuracy: 0.5% deviation
• Test Distance: 5 meters to 30 meters
• Movement: The light source remains stationary while the detector moves, ensuring stable conditions during the test.
The device is also capable of generating IES and LDT files, essential formats used in lighting design software, allowing for seamless integration into lighting projects.
LSG-6000_LM-79 Moving Detector Goniophotometer (Mirror Type C)
5. Measurement Process: How Light Intensity is Measured in Goniophotometers
The measurement process in the LISUN LSG-6000 is systematic and follows these steps:
• Setup of Light Source: The light source is placed in the goniophotometer’s test area.
• Calibration: The device is calibrated using a reference light source to ensure measurement accuracy.
• Rotation: The detector moves around the light source in a circular motion. For each angular position, the luminous intensity is recorded.
• Data Recording: Light intensity is measured in candelas at each angular position.
• Data Processing: The goniophotometer software processes the data to produce a complete 3D intensity distribution profile.
6. Experimental Results
The following experiment was conducted using the LISUN LSG-6000 to measure a standard LED light source. The goal was to demonstrate how light intensity is measured in various directions and how these measurements inform product performance.

Angular Position (Degrees)
Luminous Intensity (cd)

0
2500

30
2400

60
2300

90
2200

120
2100

150
2000

180
1900

210
1800

240
1700

270
1600

300
1500

330
1400

360
2500

The results from the LISUN LSG-6000 show how light intensity changes with angular position. The maximum intensity of 2500 cd was observed at 0° and 360°, indicating that the light source is most effective in a forward-facing direction.
7. Data Interpretation
The data collected from the LISUN LSG-6000 provide a comprehensive understanding of how the light source distributes light in all directions. This 3D distribution is essential for understanding whether the light source is suitable for specific applications. For example, lighting products used in large spaces require uniform intensity across a wide angular range, whereas task lighting may need higher intensity in a specific direction.
By analyzing the data, manufacturers can optimize their products for energy efficiency and performance. Moreover, the measurements obtained using the LISUN LSG-6000 enable compliance with LM-79, ensuring that the lighting products can be marketed and sold in international markets.
8. Conclusion
In this paper, we explored how light intensity is measured in a full-space distribution photometer like the LISUN LSG-6000 LM-79 Moving Detector Goniophotometer. Light intensity, measured in candelas, is a critical parameter for ensuring that lighting products perform according to expectations and meet regulatory standards. The LISUN LSG-6000 provides a highly accurate method of measuring the spatial distribution of light, making it an essential tool for lighting manufacturers and designers.
The experiment results and the subsequent data analysis demonstrate the practical application of the goniophotometer in testing and product development. By leveraging this technology, manufacturers can create lighting solutions that are both energy-efficient and meet global standards.
References
Illuminating Engineering Society. (2019). LM-79-19 Electrical and Photometric Measurements of Solid-State Lighting Products.
LISUN Group. (n.d.). LM-79 Moving Detector Goniophotometer – LSG-6000. Retrieved from https://www.lisungroup.com/products/goniophotometer/lm-79-moving-detector-goniophotometer.html. https://www.lisungroup.com/news/technology-news/understanding-how-light-intensity-is-measured-in-full-space-distribution-photometers-using-the-lisun-lsg-6000-lm-79-moving-detector-goniophotometer.html

Comments

Post a Comment

Popular posts from this blog

What are the differences of FMVSS 302, UL94 and IEC60695 for flammability test?

Image
The flammability of different materials, such as plastics and other materials used in items such as automobile interiors, electronic devices, and electrical appliances, is evaluated using a number of different standards. Some of these standards are FMVSS 302, UL 94, and IEC 60695. Nevertheless, there are a number of important distinctions between these standards: FMVSS 302 is a specialized standard that was designed for the automotive industry to analyze the flammability of materials used in car interiors. Its purpose is to measure the combustibility of these materials. The UL 94 standard is a more comprehensive regulation that assesses the combustibility of a variety of materials, including plastics, and has applications in a number of different sectors. IEC 60695 is a global standard that is used in the process of assessing the potential for electronic and electrical equipment to catch fire. Testing Procedures The flammability of materials is determined using a variety of testing ...
Read more
Image
125 Grounding Contact Test 125.1 Grounding receptacles having a 5-15R,5-20R，6-13R，6-20R，7-15R，14-15Ror 15-15R configuration are to be subjected to the tests in this section. 125.2 Previously untested devices are to be used. Each device is to be mounted in a flush device box, or as otherwise intended, with its face in a vertical plane. A nonmetallic faceplate is to be installed if intended. A solid 14 AWG (2.1 mm2) copper conductor is to be connected to the receptacle grounding terminal. GNGPL SB1610_AL 125.3 With the receptacle oriented to create the maximum contact displacement (possible distortion of contact affecting its contact ability), the test pin A. Figure 125.1 is to be fully inserted in the grounding contact. A 5 lb (2.27 kg) weight is to be gradually suspended form the test pin 6 inches (152 mm) from the face of the receptacle. The weight is to be applied for 1 minute, following which, the weight is to be removed. The application of the weight is to be repeated with the rece...
Read more
Image
Accessible parts of equipment with standard IEC 62368 General An accessible part of an equipment is a part that can be touched by a body part. For the purposes of dctermining an accessible part, a body part is represented by one or more of the specified test probes. Accessible parts of an equipment can include parts behind a door, panel, removable cover, etc. that can be opened without the use of a tool. Accessible parts do not include those that become accessible when floor standing equipment having a mass exceeding 40 kg is tilted. For equipment intended for building-in or rack-mounting, or for subassemblies and the like for incorporation in larger equipment,accessible parts do not include those that are not accessible when the equipment or subassembly is installed according to the method of mounting or installation specified in the installation instructions. A part is considered accessible if the instructions or markings intended to be followed require that a person phys...
Read more