Introduction to Goniophotometry and Its Role in Photometric Analysis
Goniophotometers are precision instruments designed to measure the spatial distribution of light emitted from luminaires, LEDs, and other light sources. These devices provide critical data on luminous intensity, flux, and angular light distribution, enabling manufacturers and researchers to evaluate performance, compliance, and optimization of lighting systems. The measurements adhere to international standards such as IEC 60598, IEC 61341, CIE 70, and LM-79, ensuring consistency across industries.
This article examines the technical principles, key features, and applications of goniophotometers, with a focus on the LISUN LSG-6000 goniophotometer system.
Fundamental Principles of Goniophotometric Measurement
Goniophotometers operate by rotating a light source or detector along one or more axes to capture luminous intensity at varying angles. The two primary measurement configurations are:
- Type C (Moving Detector, Fixed Light Source): The detector moves along a spherical or hemispherical path while the light source remains stationary.
- Type A/B (Moving Light Source, Fixed Detector): The light source rotates while the detector remains fixed.
The LSG-6000 employs a Type C configuration with a high-precision robotic arm, ensuring minimal measurement uncertainty (±2% for luminous flux, per IEC 60598).
Key Measurement Parameters:
- Luminous Intensity Distribution (LID): Angular light emission profile.
- Total Luminous Flux: Integrated light output in lumens (lm).
- Beam Angle and Field Angle: Defined by 50% and 10% intensity thresholds.
- Color Uniformity: Spatial consistency of chromaticity (CIE 1931 xy).
Technical Specifications of the LISUN LSG-6000 Goniophotometer
The LSG-6000 is engineered for high-accuracy photometric and colorimetric testing, with the following specifications:
| Parameter | Specification |
|---|---|
| Measurement Geometry | Type C (2-axis rotation) |
| Angular Resolution | 0.1° |
| Luminous Flux Range | 0.1 lm – 2,000,000 lm |
| Spectral Range | 380 nm – 780 nm |
| Accuracy (Luminous Flux) | ±2% (per IEC 61341) |
| Compliance Standards | IEC 60598, LM-79, CIE 70, EN 13032 |
| Maximum Luminaire Size | 2,000 mm (L) × 2,000 mm (W) |
Competitive Advantages:
- Robotic Arm Precision: Reduces stray light interference, improving repeatability.
- Multi-Standard Compliance: Validates performance for global markets (EU, US, Japan).
- Automated Data Processing: Direct export to IES, LDT, and EULUMDAT formats.
Industry Applications of Goniophotometric Testing
Lighting Industry and LED/OLED Manufacturing
Goniophotometers verify compliance with energy efficiency regulations (e.g., EU Ecodesign Directive) and optimize light distribution for LED modules. The LSG-6000 is used to test:
- Street Lighting: Beam uniformity per EN 13201.
- OLED Panels: Angular color shift analysis (CIE 015:2018).
Display Equipment Testing
For LCD and micro-LED displays, the system measures viewing angle performance (ISO 9241-307).
Photovoltaic Industry
Validates solar simulator uniformity (IEC 60904-9) and anti-reflective coating efficacy.
Medical Lighting Equipment
Ensures surgical luminaires meet DIN EN 60601-2-41 for shadow-free illumination.
Compliance with International Standards
The LSG-6000 adheres to:
- IEC 61341: Center-beam intensity and beam angle.
- LM-79: Electrical and photometric testing of LED products.
- CIE 70: Measurement of absolute luminous flux.
Example: A U.S.-based LED manufacturer uses the system to generate LM-79 reports for DOE compliance.
Advanced Features for Research and Development
3D Light Distribution Modeling
The system constructs ray-traced simulations for optical design validation.
High-Speed Sampling
Capable of 10,000 data points/hour, critical for production-line QA.
Frequently Asked Questions (FAQ)
Q1: What is the typical measurement time for an LED downlight using the LSG-6000?
A: Approximately 15–20 minutes, depending on angular resolution requirements.
Q2: Can the LSG-6000 test UV or IR light sources?
A: No, its spectral range is limited to 380–780 nm.
Q3: How does the system correct for ambient light interference?
A: A darkroom environment and software-based background subtraction are applied.
Q4: Is the LSG-6000 compatible with dimmable luminaires?
A: Yes, but external dimming control must be synchronized with the goniophotometer.
Q5: What file formats are supported for test reports?
A: IES, LDT, Excel, and PDF outputs are standard.
