Introduction to Goniophotometry
A goniophotometer is a specialized optical instrument designed to measure the spatial distribution of light emitted from a source under controlled conditions. By quantifying luminous intensity, luminous flux, and angular light distribution, goniophotometers serve as critical tools in industries requiring precise photometric characterization. These instruments adhere to international standards such as IEC 60598, CIE 70, LM-79, and EN 13032, ensuring compliance with regulatory and performance benchmarks.
This article examines the technical principles of goniophotometry, its applications across multiple industries, and the capabilities of the LISUN LSG-6000, a high-precision goniophotometer engineered for rigorous testing in LED manufacturing, display calibration, and scientific research.
Fundamentals of Goniophotometric Measurement
Optical Geometry and Measurement Principles
Goniophotometers operate on the principle of angular photometry, where a light source is rotated along one or more axes while a photodetector records luminous intensity at defined angular increments. The two primary measurement configurations are:
- Type C (Moving Detector, Fixed Source): The detector traverses a spherical path around a stationary light source.
- Type A/B (Moving Source, Fixed Detector): The light source rotates while the detector remains fixed.
The LSG-6000 employs a Type C configuration, ensuring high repeatability (±1%) and minimal stray light interference. The system integrates a high-sensitivity spectrometer and a reference lumen standard for traceable calibration.
Key Measured Parameters
- Luminous Intensity Distribution (LID): Angular variation of candela values.
- Total Luminous Flux (lm): Integrated light output across all directions.
- Beam Angle and Field Angle: Derived from the angular spread at 50% and 10% of peak intensity.
- Color Uniformity: Spatial consistency of chromaticity (Δu’v’ < 0.003).
Technical Specifications of the LISUN LSG-6000
The LSG-6000 is a fully automated goniophotometer optimized for high-accuracy testing of LEDs, luminaires, and optical components. Its specifications include:
| Parameter | Specification |
|---|---|
| Measurement Distance | 5m – 30m (adjustable) |
| Angular Resolution | 0.1° (azimuth), 0.01° (elevation) |
| Luminous Flux Range | 0.1 lm – 200,000 lm |
| Spectral Range | 380 nm – 780 nm (extendable to 1700 nm) |
| Compliance Standards | IEC 60598, LM-79, CIE 121, EN 13032 |
| Data Acquisition Speed | < 10 ms per measurement point |
The system incorporates a dual-axis robotic arm for dynamic positioning, enabling 4π steradian measurements without manual intervention.
Industry Applications and Compliance with International Standards
1. Lighting Industry and LED/OLED Manufacturing
The LSG-6000 is widely used in LM-79 testing for LED luminaires, ensuring compliance with ENERGY STAR and DLC requirements. Its ability to measure near-field and far-field distributions makes it indispensable for evaluating:
- LED Chip Uniformity (per ANSI C78.377)
- OLED Panel Luminance Gradients
- Optical Efficiency of Reflector Systems
2. Display Equipment Testing
For LCD and microLED displays, the goniophotometer assesses:
- Viewing Angle Performance (per IEC 61747)
- Gamma Shift and Color Consistency
- Backlight Module Diffusion Efficiency
3. Photovoltaic and Optical Component Testing
In solar simulation, the LSG-6000 measures angular responsivity of photovoltaic cells (per IEC 60904-9). It also verifies:
- Anti-Reflective Coating Efficacy
- Light Guide Plate Homogeneity
4. Medical and Scientific Instrumentation
Medical lighting systems, such as surgical LEDs, require flicker-free operation and precise beam control. The LSG-6000 validates compliance with IEC 60601-2-41 for photobiological safety.
Competitive Advantages of the LSG-6000
- Automated Multi-Axis Positioning: Reduces human error in alignment.
- High-Speed Data Capture: Enables real-time quality control in production lines.
- Modular Spectrometer Integration: Supports CIE S 025 and IES TM-30 color fidelity analysis.
- Thermal Compensation: Maintains accuracy under varying ambient conditions.
Compared to traditional goniophotometers, the LSG-6000 achieves <1.5% uncertainty in total flux measurements, outperforming competitors in repeatability.
Frequently Asked Questions (FAQ)
Q1: What is the minimum sample size required for LSG-6000 testing?
The system accommodates light sources from 5 mm² to 2 m², suitable for micro-LEDs and large-area luminaires.
Q2: Does the LSG-6000 support near-field goniophotometry?
Yes, with an optional near-field lens module, it measures intensity distributions at distances as low as 50 cm.
Q3: Which standards does the LSG-6000 comply with for automotive lighting?
It adheres to SAE J575 and ECE R37 for headlamp and signal light testing.
Q4: Can the system measure UV and IR emissions?
With an extended-range spectrometer, it covers 170–2500 nm for specialized applications.
Q5: How does the LSG-6000 handle high-power light sources?
The water-cooled detector option prevents saturation when testing sources exceeding 50,000 lm.
This article underscores the LSG-6000 as a benchmark instrument in photometric validation, aligning with global standards while addressing diverse industrial demands.
