Abstract
Goniometer light measurement serves as the cornerstone of accurate optical performance evaluation for solid-state lighting (SSL) products. With the 2025 release of ANSI/IES LM-79-24, the latest iteration of SSL photoelectric testing standards, manufacturers require advanced goniometric systems to meet updated regulatory demands while maintaining compatibility with prior benchmarks like LM-79-19. This paper examines the technical principles of goniometer light measurement and systematically verifies how the LISUN LSG-6000 LM-79 Moving Detector Goniophotometer (Mirror Type C) fulfills both legacy and contemporary LM-79 requirements. Through analysis of its mechanical design, measurement capabilities, and test data validation, this study confirms the instrument’s suitability for comprehensive SSL product testing across diverse applications.
1. Introduction
1.1 Significance of Goniometer Light Measurement
SSL technologies, including LED and OLED lighting, have revolutionized the illumination industry with their energy efficiency and long lifespan. However, their optical performance varies significantly across designs, necessitating precise characterization of light distribution patterns and photometric parameters. Goniometer light measurement addresses this need by quantifying angular light intensity distribution, enabling derivation of critical metrics such as total 光通量 (luminous flux), efficacy, and glare indices. This measurement method is indispensable for quality control, product certification, and compliance with global energy efficiency regulations.
1.2 Evolution of LM-79 Standards
The ANSI/IES LM-79 series represents the global benchmark for SSL photoelectric testing. LM-79-19, released in 2019, established unified protocols for evaluating LED and OLED products, while the 2025 LM-79-24 update introduced targeted improvements to align with technological advancements. Key revisions include updated normative references, new definitions like “photometric center,” adjusted circuit capacitance limits, simplified harmonic distortion measurement, and enhanced 光通量 testing 原理 documentation. Compliance with both standards is critical for manufacturers targeting international markets, as they underpin certifications such as Energy Star (U.S.), VEET (Australia), and DLC (North America).
1.3 Objectives and Scope
This paper aims to: (1) clarify the role of goniometer light measurement in meeting LM-79 requirements; (2) detail the technical specifications of the LISUN LSG-6000 system; (3) validate its compliance with LM-79-19 and LM-79-24 through performance analysis and data verification; and (4) demonstrate its applicability across SSL product categories.
LM-79 Moving Detector Goniophotometer (Mirror Type C)
2. Theoretical Framework: Goniometer Light Measurement and LM-79 Requirements
2.1 Principles of Mirror-Type Moving Detector Goniometry
The LISUN LSG-6000 employs a Mirror Type C configuration, a variant of moving detector goniometers defined by EN13032-1 Clause 6.1.1.3 (Type 4). This design maintains the test luminaire in a fixed position while a photometer and mirror assembly rotate around it, enabling 3D angular measurement (γ: ±180° or 0~360°). The stationary luminaire setup eliminates mechanical stress on the device under test, ensuring stable thermal conditions critical for accurate SSL measurements. Laser calibration aligns the luminaire’s photometric center with the rotation axis, directly addressing LM-79-24’s new requirement for precise identification of this reference point.
2.2 Core LM-79 Measurement Parameters
Both LM-79-19 and LM-79-24 mandate comprehensive testing of optical and electrical parameters. Optical parameters include total Luminous flux (lm), efficacy (lm/W), angular Light intensity distribution，chromaticity coordinates, correlated color temperature (CCT), and Color rendering index (CRI). Electrical parameters encompass RMS voltage/current, active power, power factor, and total harmonic distortion (THD). LM-79-24 extends these requirements by adding radiation and photon flux measurements, reflecting the growing demand for spectral characterization in applications like Plant lighting.
2.3 Critical Standard Updates in LM-79-24
Table 1 summarizes key differences between LM-79-19 and LM-79-24 that impact goniometer light measurement.
Aspect
ANSI/IES LM-79-19
ANSI/IES LM-79-24
Implications for Goniometry
Normative References
IES RP-16-17, LM-78-17
IES LS-1-22, LM-78-20
Requires updated calibration and measurement protocols
Photometric Center
Not defined
Newly established reference point
Demands precise luminaire alignment
Circuit Capacitance
≤1.5 nF
≤2.0 nF
Improves compatibility with modern SSL drivers
THD Measurement
2-100 (1 MHz instruments)
2-50 (all instruments)
Simplifies testing without compromising accuracy
Luminous flux principle
Limited description
Integrated Angular Measurements added
Requires goniometer software support for new calculation methods
3. Technical Overview of LISUN LSG-6000 Goniophotometer
3.1 Mechanical and Electrical Design
The LSG-6000 incorporates high-precision components to ensure measurement reliability. Its drive system uses Mitsubishi servo motors and German encoders, achieving angular precision of 0.05° and resolution of 0.001°—exceeding LM-79’s minimum requirements for measurement granularity. The system supports test distances from 5m to 30m, configurable to accommodate different luminaire sizes and optical characteristics. Multiple model variants cater to diverse testing needs, as shown in Table 2.
Model Variant
Max Luminaire Size (Φ×F)
Max Load
Max Power
Minimum Darkroom Height
LSG-6000S
1200×500mm
40kg
600V/10A
3.0m
LSG-6000 (Std)
1600×600mm
50kg
600V/10A
4.1m
LSG-6000B
1800×800mm
60kg
600V/10A
4.7m
LSG-6000L
2000×900mm
80kg
600V/10A
5.2m
3.2 Photometric and Spectral Capabilities
At the core of the LSG-6000’s measurement system is a Class L photometric probe (f1′0.99), confirming measurement reliability.
4.4 Application Versatility
The LSG-6000’s compliance extends across diverse SSL product categories covered by LM-79 standards, including:
• Indoor/outdoor LED luminaires
• All-in-one LED/OLED bulbs
• LED Light Engines
• HID replacement LED fixtures
• Plant Lighting systems (via LSG-6000CCD’s PAR/PPF testing)
• UV lighting (UVA: 320-400nm; UVB: 275-320nm; UVC: 200-275nm)
This versatility makes it a comprehensive solution for manufacturers producing multiple SSL product lines.
5. Discussion and Comparative Advantages
5.1 Technical Advantages Over Legacy Systems
Compared to predecessor models (LSG-3000/5000), the LSG-6000 offers several improvements aligned with LM-79 evolution:
• Extended load capacity and size compatibility for larger luminaires
• Higher angular precision enabling more detailed light distribution analysis
• Integrated spectral measurement options for LM-79-24’s expanded parameters
• Flexible test distance configuration to meet different goniometry requirements
5.2 Compliance Challenges Addressed
SSL testing faces unique challenges such as thermal drift, driver compatibility, and complex light distributions. The LSG-6000 mitigates these through:
• Stable mechanical design minimizing vibration-induced measurement error
• Wide voltage/current range (600V/10A AC/DC) supporting diverse driver technologies
• Advanced software algorithms for processing non-uniform light distributions
5.3 Global Certification Alignment
Beyond LM-79 standards, the LSG-6000 complies with international benchmarks including CIE S025, EN13032-1, SASO2902, and GB/T 24824. This multi-standard compatibility streamlines certification for global markets, reducing testing costs and time-to-market.
6. Conclusion
Goniometer light measurement is essential for validating SSL product performance against LM-79 standards, and the transition to LM-79-24 demands advanced testing equipment capable of adapting to new requirements while maintaining legacy compatibility. The LISUN LSG-6000 LM-79 Moving Detector Goniophotometer (Mirror Type C) meets this challenge through its high-precision mechanical design, compliant photometric components, and updated software algorithms. Experimental data confirms its accuracy across all critical LM-79-19 and LM-79-24 parameters, while its versatile design accommodates diverse SSL product types. For manufacturers seeking reliable, compliant goniometer light measurement solutions, the LSG-6000 represents a technically robust choice that supports global market access and quality assurance. https://www.lisungroup.com/news/technology-news/goniometer-light-measurement-compliance-of-lisun-lsg-6000-with-ansi-ies-lm-79-24-and-lm-79-19-standards.html
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