Title: Goniophotometer for Sale: Comprehensive Guide to LISUN’s Precision Photometric Testing Solutions
Abstract
The accurate characterization of spatial light distribution is fundamental to the design, certification, and quality control of modern luminaires. This document provides a technical examination of the LSG-6000 and LSG-1890B Goniophotometer Test Systems developed by LISUN. Designed to meet the stringent requirements of international photometric standards, these instruments facilitate the measurement of luminous intensity, luminous flux, color uniformity, and beam angle for a broad spectrum of optical sources. This guide details operational principles, mechanical architecture, compliance with regulatory frameworks, and application-specific utility across industries including solid-state lighting, display manufacturing, and photovoltaic testing.
1. Photometric Measurement Architecture and Dual-Axis Rotational Kinematics
The LISUN LSG-6000 and LSG-1890B systems employ a dual-axis goniometric framework that enables the acquisition of light intensity data across a spherical coordinate system. Unlike near-field or mirror-based goniophotometers, these systems utilize a direct-measurement approach where the luminaire is physically rotated along both the gamma (vertical) and C (horizontal) axes. The LSG-6000 operates with a Type C (IESNA LM-79-19) coordinate system, supporting a maximum test luminaire weight of 50 kg and a physical diameter up to 1.6 meters. The LSG-1890B, designed for smaller-to-moderate fixtures, handles luminaires up to 30 kg with an angular resolution of 0.1°.
The rotational kinematics are driven by servo-controlled stepper motors, ensuring positional repeatability within ±0.05°. The detector arm, equipped with a Class 1 photometric probe (CIE 69 compliant), remains stationary while the luminaire rotates. This configuration eliminates errors introduced by moving a detector through a non-uniform ambient field. The darkroom enclosure, constructed from matte-black aluminum sheets, minimizes stray light interference. For large-format luminaires, the LSG-6000 supports an optional gantry system to accommodate asymmetric or high-wattage industrial fixtures.
2. Spectral Correction and High-Precision Luminance Determination
Central to the accuracy of any goniophotometer is its photometric detector’s spectral responsivity. LISUN integrates a corrected silicon photodiode whose spectral response is matched to the CIE 1924 photopic luminosity function V(λ). The detector features a cosine-corrected diffuser to maintain angular accuracy for incident light up to 65° off-axis.
For colorimetric characterization, the LSG-6000 and LSG-1890B can be outfitted with a spectroradiometric module (e.g., the LISUN LPCE-2 system). This module captures spectral power distributions (SPDs) at each test point, enabling the calculation of correlated color temperature (CCT), color rendering index (CRI) per CIE 13.3-1995, and TM-30 metrics (Rf and Rg). Chromaticity coordinates are reported with a typical uncertainty of ±0.002 in the CIE 1931 (x, y) diagram. The integration of a high-speed spectrometer (wavelength range 380–780 nm, resolution 0.5 nm) allows for simultaneous photometry and colorimetry during a single angular sweep, reducing total test time by up to 40% compared to sequential measurement protocols.
3. Compliance with International Photometric Standards (IEC, IESNA, CIE, and JIS)
LISUN goniophotometers are engineered to comply with a suite of mandatory and recommendation-level standards. The following table summarizes the relevant regulatory frameworks:
| Standard | Scope | Key Requirement | LISUN Compliance Feature |
|---|---|---|---|
| IES LM-79-19 | Electrical and photometric testing of solid-state lighting products | Type C goniometry, 2% luminous flux uncertainty, 1 nm spectral resolution for chroma | LSG-6000 angular step down to 0.1°, built-in spectral correction |
| CIE S025/E:2015 | Test method for LED lamps, luminaires, and modules | Reference conditions at 25°C, stabilization time ≥30 min | Integrated temperature-controlled darkroom; real-time monitoring |
| IEC 62722-2-1 | Performance requirements for LED luminaires | Luminous flux measurement with total uncertainty ≤3% | Calibrated integrating sphere crossover validation |
| JIS C 8154 | Measuring method of luminous intensity distribution for LED lighting | Type C coordinate system, 0.5° step for indoor luminaires | Software-selectable step increments (0.1° to 5°) |
| IEC 60969 | Self-ballasted lamps for general lighting | Photometric stability testing under cyclic voltage conditions | Power supply monitoring with ±0.5% voltage regulation |
The LSG-1890B, in particular, satisfies the angular resolution requirements of IES LM-79-19 for recessed and track lighting fixtures. Both models support automated flux calculation using the zonal cavity method (CIE 84) and provide raw data export in IES LM-63, EULUMDAT (LDT), and CIBSE TM-14 formats for seamless import into lighting design software such as Dialux and RELUX.
4. Application in LED and OLED Manufacturing and Quality Assurance
The production environment for LED arrays and OLED panels demands high-speed, repeatable photometric testing. In LED manufacturing, binning processes require precise determination of luminous flux and chromaticity at multiple drive currents. The LSG-6000’s automated sweep function, combined with a programmable DC power supply (up to 500V/5A), enables batch testing of modules with minimal operator intervention.
For OLED panels used in architectural or automotive lighting, the goniophotometer provides critical data on Lambertian emission characteristics and angular color uniformity. The LSG-1890B’s small physical footprint (2.5m × 2.5m) allows installation directly within production cleanrooms. A typical use case involves measuring a 300mm × 400mm OLED tile at 0.5° angular increments across a 180° horizontal plane. The system records intensity in 15,000+ spatial points; post-processing software flags deviations beyond a 5% threshold from the nominal luminance distribution. In display equipment testing, the goniometer evaluates backlight uniformity for LCD modules, measuring luminance over a 120° viewing cone to validate compliance with VESA DisplayHDR standards.
5. Utilization in the Photovoltaic Industry for Solar Simulator Calibration
Although primarily designed for photometry, the LISUN goniophotometer architecture is adapted for photovoltaic (PV) applications through the LSG-6000-PV variant. This configuration replaces the standard photometric detector with a spectrally flat radiometric head (calibrated to NIST-traceable standards, 300–1100 nm) to measure the spatial non-uniformity of solar simulators per IEC 60904-9.
The measurement protocol involves mounting a small-area reference cell (typically 20mm × 20mm) on the goniometer arm and scanning the simulator’s test plane at 2mm resolution. The software calculates the betweenness coefficient and spectral mismatch factor (MMF) according to ASTM E927-19. This application is critical in the calibration of multi-junction PV cells used in concentrator photovoltaic (CPV) systems, where beam non-uniformities of less than 1% are required to prevent localized heating and efficiency losses. The LSG-6000-PV achieves a spatial uniformity measurement uncertainty of ±0.3% across a 2m × 2m plane.
6. Advanced Testing for Urban Lighting Design and Stage and Studio Luminaires
Urban lighting design relies on precise isocandela diagrams and utilization factors to optimize pole spacing and glare control. The LSG-6000 supports mounting of full-size roadway luminaires (up to 1.6m in diameter) for testing per IES RP-8-21. The system outputs vertical illuminance at calculated roadway grid points, directly feeding into glare rating calculations (e.g., TI – Threshold Increment). One study using an LSG-6000 to analyze a 280W LED streetlight found that the maximum beam angle at C0/180° was 138°, with a luminous flux of 24,380 lumens and a light loss factor (LLF) of 0.92.
In the stage and studio lighting sector, the goniophotometer evaluates moving heads, wash lights, and follow spots. These fixtures often require measurement of zoom ranges and gobo projection uniformity. The LSG-1890B’s capability to trigger measurement at variable rotation speeds (up to 30°/s) accommodates the large throw distances common in theater environments. Measurements are taken at multiple focal positions; the system’s software integrates a beam angle analysis tool that calculates field angle (50% intensity) and cutoff angle (10% intensity) per DIN 5032-7.
7. Medical Lighting Equipment and Sensor Testing Protocol
The manufacture of surgical luminaires, dental curing lights, and diagnostic examination lamps requires adherence to IEC 60601-2-41 (Medical Electrical Equipment—Particular Requirements for Operating Lights) and ISO 12023. LISUN goniophotometers enable testing of these devices under standardized conditions.
For a typical 40cm-diameter surgical light, the LSG-6000 measures illuminance uniformity within the central 20cm field, central illuminance (required >40,000 lux for Class I lights), and shadow dilution as per the standard’s procedure. The goniometer rotates the luminaire 45° off-axis to simulate typical surgical positioning, while the detector remains at the nominal working distance (usually 1.0m). The software reports color temperature stability (ΔCCT < ±50K) during dimming cycles from 100% to 20% output.
For optical component production, such as Fresnel lenses, diffusers, and reflectors, the goniophotometer quantifies transmissive angular profiles. The LSG-1890B is fitted with a collimated light source and a sample rotator stage. The luminance distribution of the transmitted beam is measured every 0.2°; the half-maximum width and stray light proportion are calculated per ISO 15368. For sensor manufacturing, the system simulates incident angles from 0° to 85° to characterize responsivity vs. angle for photodiodes and ambient light sensors, essential for calibration of automotive driver monitoring systems.
8. Comparative Analysis: LSG-6000 vs. LSG-1890B – Selection Criteria
The choice between the LSG-6000 and LSG-1890B is governed by luminaire size, measurement resolution, and throughput requirements.
| Parameter | LSG-6000 | LSG-1890B |
|---|---|---|
| Maximum luminaire weight | 50 kg | 30 kg |
| Maximum luminaire diameter | 1.6 m | 0.8 m |
| Angular step resolution | 0.1° (minimum) | 0.1° (minimum) |
| Rotational axes | Gamma (0–360°), C (0–360°) | Gamma (0–360°), C (0–360°) |
| Standard measurement distance | 3 m / 5 m (optional) | 2 m / 3 m (optional) |
| Applicable standards | LM-79, IEC 62722, JIS C 8154 | LM-79, CIE S025, IEC 60969 |
| Recommended industry | Large roadway, stadium, high-bay | Track lighting, downlights, OLED panels |
The LSG-6000 includes an embedded darkroom with a 5m photometric path, reducing errors from near-field absorption. The LSG-1890B offers a compact footprint (≤6 m²), making it suitable for laboratory expansion in existing R&D facilities. Both models are supplied with LISUN’s proprietary measurement software, which provides real-time polar curve plotting, isocandela contour mapping, and automated report generation in PDF or Excel format.
9. Calibration Traceability, Data Integrity, and Long-Term Stability
Long-term measurement consistency is maintained through an internal calibration protocol employing a NIST-traceable standard lamp (CIE Source A, color temperature 2856K). The LSG series goniophotometers incorporate a self-diagnostic routine that checks for detector drift, motor backlash, and ambient light leakage before each test sequence. Calibration intervals of 12 months are recommended for laboratories performing compliance testing; a field calibration kit (LSK-01) is available for in-house verification.
Data integrity is assured through redundant logging and encrypted file storage. The measurement software timestamp each recorded intensity value and logs ambient temperature and humidity, enabling post-hoc compensation for environmental drift. For an R&D lab testing different batches of LED modules, the system tracks statistical distributions (mean, standard deviation, and Cp/Cpk values) of luminous flux and CCT over time, supporting ISO 17025-accredited quality systems.
10. Future Extensibility and Integration with Automated Production Lines
Both the LSG-6000 and LSG-1890B support integration into Industry 4.0 environments. The systems offer RS-232, USB 3.0, and Ethernet interfaces, with an optional OPC-UA server for direct connection to MES (Manufacturing Execution Systems). For high-throughput applications, a conveyor-fed variant allows for inline sampling of luminaires at a rate of 30 units per hour.
The firmware is upgradable to support emerging standards such as CIE S 026 (metameric indices) and the upcoming IEC 63103 for lighting system energy performance. LISUN provides SDK libraries (Python and LabVIEW) for custom test sequence scripting, enabling laboratories to design specialized measurement routines for biomedical optics, holographic display evaluation, or quantum dot LED (QLED) angular characterization.
Frequently Asked Questions (FAQ)
1. What is the typical measurement uncertainty of the LSG-6000 for total luminous flux?
The LSG-6000, when calibrated with a NIST-traceable standard lamp and used in a controlled laboratory environment (23°C ± 1°C), achieves a total luminous flux measurement uncertainty of ±2.0% (k=2). For relative photometric measurements (e.g., intensity distribution), the uncertainty reduces to ±1.0%.
2. Can the LSG-1890B test luminaires with asymmetric beam patterns, such as wallwash fixtures?
Yes. The LSG-1890B’s Type C goniometer supports full 360° rotation on both axes. For asymmetric fixtures, the software provides a user-defined C-plane orientation (e.g., C90/C270 for wallwash distribution) and computes vertical beam angle symmetry indices per IES LM-79.
3. What is the minimum luminaire size that can be reliably measured by these systems?
Both systems can test luminaires with a minimum luminous flux of 5 lumens. For very small sources (e.g., 1 mm² LED chips), a near-field attachment or a precision aperture may be required to reduce stray light. The standard minimum detector distance is 2m, ensuring the far-field condition (distance ≥ 5× luminaire diagonal) is satisfied.
4. Does LISUN provide software for generating reports compliant with Energy Star or DLC (DesignLights Consortium) requirements?
The LSG-6000 and LSG-1890B software includes pre-configured report templates for LM-79 test data, including CCT, CRI, power factor, and efficacy. These outputs are formatted to meet the data submission guidelines of Energy Star (EPA) and DLC Premium v5.1. The software also exports raw data in XML format for third-party auditing.
5. How does the system compensate for ambient temperature fluctuations during prolonged test sequences?
An integrated PT100 temperature sensor monitors the internal darkroom air temperature (±0.1°C resolution). If the temperature deviates by more than ±2°C from the setpoint (default 25°C), the system halts testing and records a flag in the dataset. For critical measurements, an external Peltier module is available as an option to actively stabilize the air temperature within 25°C ± 0.5°C.