{"id":9302,"date":"2026-07-20T17:47:57","date_gmt":"2026-07-20T09:47:57","guid":{"rendered":"https:\/\/ledtestsystem.com\/?p=9302"},"modified":"2026-07-20T17:47:57","modified_gmt":"2026-07-20T09:47:57","slug":"mirror-goniophotometer-for-precise-led-light-distribution-measurement","status":"publish","type":"post","link":"https:\/\/ledtestsystem.com\/ar\/%d8%a7%d9%84%d9%85%d8%af%d9%88%d9%86%d8%a7%d8%aa\/mirror-goniophotometer-for-precise-led-light-distribution-measurement\/","title":{"rendered":"Mirror Goniophotometer for Precise LED Light Distribution Measurement"},"content":{"rendered":"<p><strong>Technical Specification and Application of the Mirror Goniophotometer for High-Precision LED Light Distribution Measurement<\/strong><\/p>\n<p><strong>Introduction: Metrological Foundations for Solid-State Lighting Characterization<\/strong><\/p>\n<p>The transition from traditional incandescent and high-intensity discharge (HID) sources to solid-state lighting (SSL) based on Light Emitting Diodes (LEDs) has imposed stringent new demands on photometric measurement instrumentation. Unlike isotropic or near-isotropic emitters, LEDs exhibit highly directional, spatially non-uniform luminance profiles, often characterized by sharp intensity gradients and distinct color shifts over angle. Accurately capturing the spatial luminous intensity distribution\u2014the <em>photometric solid<\/em>\u2014is essential for predicting luminaire performance in real-world applications, from architectural lighting to medical devices.<\/p>\n<p>While conventional flat-field <a href=\"https:\/\/www.lisungroup.com\/products\/goniophotometer\/lm-79-moving-detector-goniophotometer.html\" target=\"_blank\" rel=\"noopener\">\u0645\u0642\u0627\u064a\u064a\u0633 \u0627\u0644\u0636\u0648\u0626\u064a\u0629 \u0627\u0644\u062c\u0648\u0646\u0648\u0641\u0648\u062a\u0648\u0645\u062a\u0631\u064a\u0629<\/a> and rotating luminaire systems have served the industry for decades, they present systematic limitations when measuring high-power or compact LED sources. The Mirror Goniophotometer, specifically the <a href=\"https:\/\/www.lisungroup.com\/products\/goniophotometer\/\" target=\"_blank\" rel=\"noopener\">\u0644\u064a\u0633\u0648\u0646<\/a> LSG-6000 and LSG-1890B systems, provides a solution that mitigates parasitic stray light, eliminates centering errors inherent in rotating the Device Under Test (DUT), and adheres to the rigorous requirements of CIE S 025 and LM-79-19. This article delineates the operational principles, technical architecture, and application-specific advantages of mirror-based systems, with a particular focus on the LISUN LSG-6000\/1890B platforms.<\/p>\n<p><strong>1. Principle of Operation: The C-\u03b3 Coordinate System and the Rotating Mirror Assembly<\/strong><\/p>\n<p>The fundamental distinction between a conventional <a href=\"https:\/\/www.lisungroup.com\/products\/goniophotometer\/lm-79-moving-detector-goniophotometer.html\" target=\"_blank\" rel=\"noopener\"><a href=\"https:\/\/www.ledphotometer.com\/products\/lm-79-moving-detector-goniophotometer-mirror-type-c\/\" target=\"_blank\" rel=\"noopener\">\u0645\u0642\u064a\u0627\u0633 \u0627\u0644\u0632\u0648\u0627\u064a\u0627 \u0627\u0644\u0636\u0648\u0626\u064a\u0629<\/a><\/a> and a <a href=\"https:\/\/www.lisungroup.com\/products\/goniophotometer\/lm-79-moving-detector-goniophotometer.html\" target=\"_blank\" rel=\"noopener\">mirror goniophotometer<\/a> lies in the kinematic configuration of the measurement axes. In the LISUN LSG-6000\/1890B design, the luminaire remains <em>stationary<\/em> throughout the test procedure. This is critical for large, heavy, or thermally sensitive luminaires\u2014such as stadium floodlights or high-bay industrial fixtures\u2014where gravitational sag or internal coolant redistribution during rotation would corrupt photometric data.<\/p>\n<p>The system operates on the widely accepted C-\u03b3 (Cylindrical) coordinate system, as defined by the Illuminating Engineering Society (IES LM-75) and the International Commission on Illumination (CIE 121). The measurement armature consists of a front-surface mirror mounted on a precision rotary stage. The DUT is oriented in a fixed position, emitting light toward the mirror. The mirror redirects the beam horizontally to a far-field photometer head (typically a Class L detector per CIE 69) positioned at a fixed distance of 25 meters or 30 meters, depending on the installation.<\/p>\n<p>Two axes of rotation are achieved:<\/p>\n<ul>\n<li><strong>\u03b3 (gamma) axis:<\/strong> The mirror rotates in the vertical plane, scanning the luminaire\u2019s photometric output at incremental polar angles (typically 0.1\u00b0 to 1.0\u00b0 steps).<\/li>\n<li><strong>C (C-plane) axis:<\/strong> The entire mirror-arm assembly revolves around the vertical axis of the DUT, enabling measurement in multiple azimuthal planes.<\/li>\n<\/ul>\n<p>This configuration allows the detector to remain stationary, eliminating the need for slip rings or heavy cabling on the measurement side, and drastically reduces the angular uncertainty introduced by mechanical play in large rotating structures.<\/p>\n<p><strong>2. Architectural Design and Core Specifications of the LSG-6000 and LSG-1890B Systems<\/strong><\/p>\n<p>The LISUN LSG-6000 and LSG-1890B are distinguished by their optical path length, maximum DUT mass capacity, and angular resolution. The LSG-6000 is engineered for very large luminaires (up to 50 kg), such as foundry LED high-bays and architectural floods, while the LSG-1890B is tailored for medium to large luminaires (up to 30 kg) such as streetlight modules and grow-light panels.<\/p>\n<p><em>Table 1. Comparative Specifications of LISUN Mirror Goniophotometer Systems<\/em><\/p>\n<table>\n<thead>\n<tr>\n<th style=\"text-align: left\">\u0627\u0644\u0645\u0639\u0644\u0645\u0629<\/th>\n<th style=\"text-align: left\">LSG-6000<\/th>\n<th style=\"text-align: left\">LSG-1890B<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"text-align: left\"><strong>Optical Path Length<\/strong><\/td>\n<td style=\"text-align: left\">30 m (effective)<\/td>\n<td style=\"text-align: left\">25 m (effective)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Maximum DUT Mass<\/strong><\/td>\n<td style=\"text-align: left\">50 kg<\/td>\n<td style=\"text-align: left\">30 kg<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Maximum DUT Dimensions<\/strong><\/td>\n<td style=\"text-align: left\">2000 mm diameter<\/td>\n<td style=\"text-align: left\">1600 mm diameter<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Angular Resolution (\u03b3 axis)<\/strong><\/td>\n<td style=\"text-align: left\">0.1\u00b0 (standard), 0.05\u00b0 (high-res mode)<\/td>\n<td style=\"text-align: left\">0.1\u00b0<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>C-Plane Rotation<\/strong><\/td>\n<td style=\"text-align: left\">0\u00b0 \u2013 360\u00b0, continuous<\/td>\n<td style=\"text-align: left\">0\u00b0 \u2013 360\u00b0, continuous<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Photometer Linearity<\/strong><\/td>\n<td style=\"text-align: left\">\u00b10.2% (classes L and D per CIE)<\/td>\n<td style=\"text-align: left\">\u00b10.3%<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Spectral Correction<\/strong><\/td>\n<td style=\"text-align: left\">f1\u2019 \u2264 1.5% (V(\u03bb) matching)<\/td>\n<td style=\"text-align: left\">f1\u2019 \u2264 2.0%<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Rotation Speed<\/strong><\/td>\n<td style=\"text-align: left\">Max 6\u00b0\/s<\/td>\n<td style=\"text-align: left\">Max 8\u00b0\/s<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Both systems incorporate a high-speed, high-precision photometric detector with integral colorimetry capability (optional tristimulus colorimeter for CCT, CRI, and TM-30 analysis). The LSG-6000 achieves a stray light suppression ratio greater than 10\u207b\u2076, rendering it suitable for high-power LED arrays where specular reflections from the housing could otherwise contaminate dark-field measurements.<\/p>\n<p><strong>3. Photometric Accuracy and Stray Light Mitigation in Mirror-Based Configurations<\/strong><\/p>\n<p>A critical advantage of the mirror goniophotometer over the rotating-luminaire alternative is the substantial reduction in <em>near-field to far-field coupling errors<\/em>. When a luminaire rotates, its housing and optical elements move through the detector\u2019s field of view at varying distances, causing non-uniform vignetting and spurious reflections. In the LSG-6000\/1890B, the fixture is stationary; only the collimated beam path is altered.<\/p>\n<p>Furthermore, the fixed orientation facilitates consistent thermal management. For LED luminaires, the junction temperature directly affects luminous flux and chromaticity (as per the Shockley equation and the Arrhenius degradation model). A moving luminaire changes its convective boundary layer; a stationary luminaire, attached to a temperature-controlled baseplate, maintains thermal equilibrium. This ensures that the measured luminous intensity distribution corresponds to the fixture\u2019s stable operating point, typically 25\u00b0C \u00b1 1\u00b0C ambient.<\/p>\n<p>Stray light is further controlled through a combination of:<\/p>\n<ul>\n<li>Optical baffles within the 25 m\/30 m tunnel.<\/li>\n<li>Blackout curtains and matte finishes on the mirror backplane.<\/li>\n<li>Aperture stops on the photometer to limit solid-angle acceptance to less than 1\u00b0.<\/li>\n<\/ul>\n<p>These design elements ensure conformance with the <em>IES LM-79-19<\/em> requirement for total flux uncertainty below \u00b11.5% (k=2) and intensity distribution reproducibility within \u00b10.5%.<\/p>\n<p><strong>4. Compliance with International Photometric Standards: CIE, IES, and ENEC<\/strong><\/p>\n<p>The LSG-6000 and LSG-1890B are calibrated to meet a comprehensive set of international standards governing light distribution measurement:<\/p>\n<ul>\n<li>\n<p><strong>CIE S 025\/E:2015 (Test Method for LED Lamps, LED Luminaires and LED Modules):<\/strong> This standard specifies the use of a goniophotometer with a minimum angular resolution of 0.2\u00b0 for detailed intensity data. The LSG series meets or exceeds this with 0.1\u00b0 resolution. The standard also mandates corrections for self-absorption and spectral mismatch, both of which are automated in the LISUN software suite.<\/p>\n<\/li>\n<li>\n<p><strong>IES LM-79-19 (Electrical and Photometric Measurements of Solid-State Lighting Products):<\/strong> This document explicitly requires measurement in the C-\u03b3 coordinate system for general service LED luminaires. The LISUN software exports data files in IES LM-63 (.ies) and EULUMDAT (.ldt) formats, which are universally accepted by lighting design software such as DIALux, Relux, and AGi32.<\/p>\n<\/li>\n<li>\n<p><strong>DIN EN 13032-1 \/ -4 (Light and Lighting \u2013 Measurement and Presentation of Photometric Data):<\/strong> European standards governing the measurement of luminaires for indoor and outdoor applications. The LSG-1890B is frequently utilized in ENEC certification laboratories across Germany and the Netherlands.<\/p>\n<\/li>\n<li>\n<p><strong>GB\/T 9468 (China) \/ JIS C 8105 (Japan):<\/strong> While these are national equivalents, the LISUN system\u2019s calibration is traceable to the National Institute of Metrology (NIM), ensuring compatibility for global OEMs exporting to Asian markets.<\/p>\n<\/li>\n<\/ul>\n<p>The absolute calibration of the photometric detector is performed using a standard lamp traceable to NIST (USA), PTB (Germany), or NIM (China) using a substitution method. The system\u2019s photometric distance is verified via the inverse-square law using a control luminaire with known Far-Field Zonal Flux.<\/p>\n<p><strong>5. Industry-Specific Applications: From Stage Lighting to Photovoltaic Concentrators<\/strong><\/p>\n<p>The versatility of the mirror goniophotometer is demonstrated across multiple technology sectors.<\/p>\n<p><strong>5.1. Stage and Studio Lighting (Entertainment and Broadcast)<\/strong><br \/>\nProfessional moving-head luminaires and ellipsoidal reflector spotlights (ERS) require precise intensity mapping for gobo projection and beam angle control. The LSG-6000 can measure beam angles from 2\u00b0 (narrow spot) to 60\u00b0 (wide flood) with an angular accuracy of \u00b10.1\u00b0. The system captures the <em>field angle<\/em> (where intensity falls to 10% of peak) and the <em>beam angle<\/em> (50% of peak), data critical for DMX-based lighting control and photometric plots used by lighting directors according to ANSI E1.9-2019.<\/p>\n<p><strong>5.2. Medical Lighting Equipment (Surgical Luminaires and Phototherapy Systems)<\/strong><br \/>\nSurgical overhead lights must meet strict uniformity criteria per IEC 60601-2-41, requiring a center-to-edge illuminance uniformity of less than 3:1. The stationary DUT capability of the LSG-1890B is ideal for these large, heavy, sterile housings. The measurement of Luminance Field of View (LFoV) and the depth of illumination (D50 diameter) is accurately resolved when the mirror goniophotometer scans the entire light field without mechanical vibration from rotation of the luminaire itself.<\/p>\n<p><strong>5.3. Photovoltaic Industry (Concentrator Photovoltaics and Solar Simulators)<\/strong><br \/>\nAlthough primarily a photometric device, the mirror goniophotometer geometry is employed to test the intensity distribution of solar simulators and CPV (Concentrating Photovoltaic) optical components. The angular uniformity of a Fresnel lens or a parabolic trough mirror directly correlates with cell efficiency. A modified LSG-6000 equipped with a filtered photodiode (matching the ASTM AM1.5G spectrum) can map the spatial non-uniformity of a solar simulator, ensuring compliance with IEC 60904-9.<\/p>\n<p><strong>5.4. Scientific Research Laboratories (Optical Component R&amp;D)<\/strong><br \/>\nOptical scientists developing freeform lenses or TIR (Total Internal Reflection) collimators for UV-LED curing systems rely on the system\u2019s high angular resolution (0.05\u00b0) to validate ray-tracing simulations against measured data. The ability to export raw polar coordinates enables analysis in MATLAB or Python for statistical evaluation of beam asymmetry (BAT, Beam Asymmetry Threshold) and centroid shift.<\/p>\n<p><strong>5.5. Urban Lighting Design and Smart City Infrastructure<\/strong><br \/>\nFor streetlight and tunnel luminaires, compliance with CIE 140 (Road Lighting Calculations) requires homogeneous illuminance and luminance distribution on the road surface. The mirror goniophotometer\u2019s ability to measure at high resolution in the transverse direction (C=0\u00b0 to C=180\u00b0) allows urban lighting engineers to compute point-by-point illuminance on the grid. The LSG-1890B is commonly used by municipal testing bodies in the UK (BS 5489) and Australia (AS\/NZS 1158) for Type C photometry.<\/p>\n<p><strong>6. Comparative Advantages Over Flat-Field and Robotic Goniophotometers<\/strong><\/p>\n<p>The mirror configuration presents several quantifiable advantages when benchmarked against alternative architectures.<\/p>\n<p><em>Table 2. Goniophotometer Architecture Comparison<\/em><\/p>\n<table>\n<thead>\n<tr>\n<th style=\"text-align: left\">\u0645\u064a\u0632\u0629<\/th>\n<th style=\"text-align: left\">Mirror Goniophotometer (LSG-6000)<\/th>\n<th style=\"text-align: left\">Rotating Luminaire Goniophotometer<\/th>\n<th style=\"text-align: left\">Flat-Field CCD Goniophotometer<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"text-align: left\"><strong>DUT Mass Limit<\/strong><\/td>\n<td style=\"text-align: left\">Up to 50 kg, non-rotating<\/td>\n<td style=\"text-align: left\">Limited to 10\u201315 kg (torque constraints)<\/td>\n<td style=\"text-align: left\">Limited to 5 kg<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Stray Light Sensitivity<\/strong><\/td>\n<td style=\"text-align: left\">Low (stationary detector, shielded)<\/td>\n<td style=\"text-align: left\">High (detector moves with luminaire)<\/td>\n<td style=\"text-align: left\">Medium (camera vignetting)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Measurement Speed<\/strong><\/td>\n<td style=\"text-align: left\">Moderate (scanning)<\/td>\n<td style=\"text-align: left\">Fast (single rotation)<\/td>\n<td style=\"text-align: left\">Fast (snapshot)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Angular Resolution<\/strong><\/td>\n<td style=\"text-align: left\">Very High (0.1\u00b0 controlled step)<\/td>\n<td style=\"text-align: left\">High (0.1\u00b0 mechanical step)<\/td>\n<td style=\"text-align: left\">Medium (pixel pitch limit)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Thermal Repeatability<\/strong><\/td>\n<td style=\"text-align: left\">Excellent (fixture static)<\/td>\n<td style=\"text-align: left\">Poor (convection change during rotation)<\/td>\n<td style=\"text-align: left\">Good (static fixture)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Typical Uncertainty (Total Flux)<\/strong><\/td>\n<td style=\"text-align: left\">\u00b11.2% (k=2)<\/td>\n<td style=\"text-align: left\">\u00b12.0% to \u00b12.5% (k=2)<\/td>\n<td style=\"text-align: left\">\u00b12.5% to \u00b13.0% (k=2)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The robotic or multi-axis goniophotometer (where a robotic arm moves the detector around the light source) suffers from triangulation errors in the far field. Mirror systems avoid this by maintaining a fixed angular relationship between the DUT and the detector via the reflective optical path. This yields a lower combined standard uncertainty, a critical parameter for Type Approval testing where regulatory cost is high.<\/p>\n<p><strong>7. Calibration Traceability and Self-Absorption Correction Algorithms<\/strong><\/p>\n<p>A unique aspect of the LISUN LSG series is the integrated self-absorption correction. In conventional photometric spheres, the presence of the LED luminaire inside the sphere (for total flux measurement) absorbs a fraction of the light, requiring a correction factor. Similarly, in a goniophotometer, the DUT\u2019s housing can block or reflect light reaching the detector at certain angles.<\/p>\n<p>The LSG-6000 and LSG-1890B incorporate an auxiliary calibration lamp mounted at a fixed reference location. During the measurement sequence, the system performs a differential scan: first with the DUT off (background), then with the DUT on. The ratio of the reference lamp signal with and without the DUT present provides an angular self-absorption matrix. This matrix is then applied as a point-by-point multiplicative correction to the raw intensity data. This procedure is analogous to the method described in CIE 025 Section 5.4 and improves accuracy by up to 0.5% in extreme cases involving large metallized housings.<\/p>\n<p>The system also automates dark-current compensation, spectral mismatch correction (using the f1\u2019 value of the photometer and the relative SPD of the DUT), and distance correction per the inverse-square law.<\/p>\n<p><strong>8. Data Export Protocols and Software Integration for Global Compliance<\/strong><\/p>\n<p>Measurement data from the LISUN system is processed through the proprietary <em>LISUN Goniophotometry Software Suite<\/em>, which provides real-time polar plots and incremental path tracing. The software performs interpolation between measurement planes using cubic spline algorithms to meet the zonal flux density requirements of CIE 140.<\/p>\n<p>Exported file formats include:<\/p>\n<ul>\n<li><strong>IES LM-63-2002 (.ies):<\/strong> Widely used in North America for roadway and floodlighting.<\/li>\n<li><strong>EULUMDAT (.ldt):<\/strong> Required by European lighting calculation software.<\/li>\n<li><strong>CIE 102 (.cie):<\/strong> Rare but supported for academic exchanges.<\/li>\n<li><strong>XML-based data (XLSX export):<\/strong> For post-processing in statistical software.<\/li>\n<\/ul>\n<p>The software also generates a <em>Zonal Lumen Summary<\/em> report, detailing the percentage of total luminous flux in each C-plane and \u03b3-angle cone, a standard requirement for the Energy Star certification of LED luminaires.<\/p>\n<p><strong>\u0627\u0644\u0623\u0633\u0626\u0644\u0629 \u0627\u0644\u0634\u0627\u0626\u0639\u0629 (FAQ)<\/strong><\/p>\n<p><strong>Q1: Why is a mirror goniophotometer preferred over a rotating-luminaire type for high-power LED floodlights?<\/strong><br \/>\n<strong>\u0623:<\/strong> High-power LED floodlights often exceed 30 kg in mass and generate significant heat. Rotating such a fixture induces mechanical torsion and alters natural convective airflow, causing junction temperature fluctuations that affect lumen output. A mirror goniophotometer (e.g., LSG-6000) keeps the luminaire fixed, ensuring stable thermal equilibrium and eliminating mechanical stress on the fixture\u2019s wiring and optical assembly. This yields repeatable photometric data aligned with LM-79-19 thermal requirements.<\/p>\n<p><strong>Q2: Can the LISUN LSG-6000 measure color distribution (CCT and Duv) as a function of angle?<\/strong><br \/>\n<strong>\u0623:<\/strong> Yes. When equipped with the optional tristimulus colorimetry module, the LSG-6000 performs synchronized spatial color measurement. The detector captures spectrally weighted photocurrents (X, Y, Z) at each angular increment, allowing the software to calculate Correlated Color Temperature (CCT), Duv, and International Commission on Illumination (CIE) 1931 chromaticity coordinates for each \u03b3 angle and C plane. This is critical for verifying angular color uniformity (ACU) in tunable-white LED luminaires used in studio lighting.<\/p>\n<p><strong>Q3: What is the typical uncertainty budget for total luminous flux measurement on the LSG-1890B?<\/strong><br \/>\n<strong>\u0623:<\/strong> The combined expanded uncertainty (k=2) for total luminous flux using the LSG-1890B is typically \u00b11.5% to \u00b12.0% under controlled environmental conditions (23\u00b0C \u00b1 2\u00b0C, stabilized line voltage). The main contributors are: photometer calibration uncertainty (0.5%), angular alignment (0.3%), spectral mismatch (0.4%), distance measurement (0.2%), and linearity (0.3%). Traceability is maintained through a standard lamp calibrated by a National Metrology Institute.<\/p>\n<p><strong>Q4: Does the LSG-6000 comply with the testing protocols for medical lighting per IEC 60601-2-41?<\/strong><br \/>\n<strong>\u0623:<\/strong> The LSG-6000 is well-suited for this application. IEC 60601-2-41 requires measurement of the illuminance distribution at a working plane at 1 meter distance from the surgical luminaire. While the goniophotometer measures luminous intensity (candela) in the far field, the software can compute equivalent illuminance (lux) at any specified distance using inverse-square law corrections. The stationary fixture design ensures the heavy surgical lamp (frequently &gt;50 kg) is measured without mechanical risk.<\/p>\n<p><strong>Q5: What is the maintenance schedule for the mirror surface in a 30-meter optical path system?<\/strong><br \/>\n<strong>\u0623:<\/strong> The front-surface aluminum mirror is sensitive to particulate contamination. The LISUN system incorporates a retractable dust cover and an air-purge system for the mirror compartment. In a typical laboratory environment (Class 8 cleanroom or equivalent), inspection and gentle cleaning with C02 snow or optical-grade isopropanol are recommended annually. The mirror alignment (tip-tilt) should be verified every six months using a laser alignment tool to ensure the beam is correctly centered on the photometer head aperture, maintaining angular accuracy below 0.05\u00b0.<\/p>","protected":false},"excerpt":{"rendered":"<p>Technical Specification and Application of the Mirror Goniophotometer for High-Precision LED Light Distribution Measurement Introduction: Metrological Foundations for Solid-State Lighting Characterization The transition from traditional incandescent and high-intensity discharge (HID) sources to solid-state lighting (SSL) based on Light Emitting Diodes (LEDs) has imposed stringent new demands on photometric measurement instrumentation. Unlike isotropic or near-isotropic emitters, [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3510,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[680],"class_list":["post-9302","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blogs","tag-mirror-goniophotometer"],"_links":{"self":[{"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/posts\/9302","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/comments?post=9302"}],"version-history":[{"count":1,"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/posts\/9302\/revisions"}],"predecessor-version":[{"id":9303,"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/posts\/9302\/revisions\/9303"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/media\/3510"}],"wp:attachment":[{"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/media?parent=9302"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/categories?post=9302"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ledtestsystem.com\/ar\/wp-json\/wp\/v2\/tags?post=9302"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}