{"id":8843,"date":"2026-05-29T09:54:40","date_gmt":"2026-05-29T01:54:40","guid":{"rendered":"https:\/\/www.ledtestsystem.com\/?p=8843"},"modified":"2026-05-29T09:54:40","modified_gmt":"2026-05-29T01:54:40","slug":"integrating-sphere-design-and-calibration-guide","status":"publish","type":"post","link":"https:\/\/ledtestsystem.com\/ja\/%e3%83%96%e3%83%ad%e3%82%b0\/integrating-sphere-design-and-calibration-guide\/","title":{"rendered":"Integrating Sphere Design and Calibration Guide"},"content":{"rendered":"<p><strong>Technical White Paper: Precision <a href=\"https:\/\/www.lisungroup.com\/products\/led-test-instruments\/high-precision-spectroradiometer-integrating-sphere-system.html\" target=\"_blank\" rel=\"noopener\">\u7a4d\u5206\u7403<\/a> Design and Calibration for High-Fidelity Photometric, Colorimetric, and Radiometric Measurement<\/strong><\/p>\n<p><strong>Publication Classification:<\/strong> Optical Metrology and Instrumentation<br \/>\n<strong>Target Audience:<\/strong> R&amp;D Engineers, Quality Assurance Specialists, Standards Compliance Officers, Laboratory Managers<br \/>\n<strong>Revision Status:<\/strong> V2.1 \u2013 Updated for LPCE-3 (<a href=\"https:\/\/www.lisungroup.com\/\" target=\"_blank\" rel=\"noopener\">\u30ea\u30b9\u30f3<\/a>) System Integration<\/p>\n<hr \/>\n<p><strong>1. Foundational Geometry and Optical Theory of the Integrating Sphere<\/strong><\/p>\n<p>\u305d\u306e <a href=\"https:\/\/www.lisungroup.com\/products\/led-test-instruments\/high-precision-spectroradiometer-integrating-sphere-system.html\" target=\"_blank\" rel=\"noopener\">\u7a4d\u5206\u7403<\/a> functions as an optical diffuser with a high-reflectance Lambertian coating, designed to spatially integrate radiant flux from a source. For accurate total luminous flux (\u03a6_v) measurement, the sphere must adhere to the principle of a uniform radiance distribution across its interior surface. The fundamental design equation governing sphere throughput is the <em>sphere multiplier (M)<\/em>, expressed as:<\/p>\n<p><strong>M = \u03c1 \/ (1 \u2013 \u03c1(1 \u2013 f))<\/strong><\/p>\n<p>where:<\/p>\n<ul>\n<li>\u03c1 = average reflectance of the sphere coating (typically &gt;94% for spectralon or PTFE-based materials).<\/li>\n<li>f = port fraction (total area of all ports divided by the sphere surface area).<\/li>\n<\/ul>\n<p>A critical design parameter is the <em>port fraction<\/em>, which must remain below 5% to maintain linearity and minimize self-absorption errors. Custom sphere geometries, such as the 2-meter diameter units utilized in <em>Automotive Lighting Testing<\/em> facilities, incorporate ancillary baffles and light traps to reduce direct line-of-sight errors. For high-precision work in <em>Scientific Research Laboratories<\/em> \u305d\u3057\u3066 <em>Medical Lighting Equipment<\/em> verification, the sphere must include a spectroradiometric port positioned at a 90-degree angle from the sample port to avoid specular reflections.<\/p>\n<p>The LISUN LPCE-3 (LISUN) Integrating Sphere and Spectroradiometer System adheres to a 0.3-meter to 2.0-meter diameter sphere architecture, utilizing a proprietary barium sulfate and PTFE composite coating (\u03c1 \u2265 96% across 380\u2013780 nm). This coating ensures spectral flatness crucial for <em>Display Equipment Testing<\/em> \u305d\u3057\u3066 <em>LED &amp; OLED Manufacturing<\/em> where spectral power distribution (SPD) fidelity is paramount.<\/p>\n<hr \/>\n<p><strong>2. Spectral Radiance Calibration Protocols and Traceability Chain<\/strong><\/p>\n<p>Calibration of an integrating sphere system requires a multi-tiered approach, establishing traceability to a National Metrology Institute (NMI). The primary method involves a <strong>Standard Lamp Method<\/strong> (for luminous flux) and a <strong>Spectral Irradiance Transfer<\/strong> (for radiance\/color).<\/p>\n<p><em>Step 1: Spectral Responsivity Calibration.<\/em> The spectroradiometer (e.g., LISUN\u2019s high-speed CCD array) is calibrated using a NIST-traceable tungsten halogen standard lamp (CIE Illuminant A). The calibration coefficient (C(\u03bb)) is derived as:<\/p>\n<p><strong>C(\u03bb) = S_std(\u03bb) \/ R_measured(\u03bb)<\/strong><\/p>\n<p>where S_std(\u03bb) is the known spectral irradiance of the standard lamp, and R_measured(\u03bb) is the raw instrument response.<\/p>\n<p><em>Step 2: Sphere Self-Absorption Compensation.<\/em> A major source of systematic error is the self-absorption effect caused by the device under test (DUT) obstructing internal light paths. The LPCE-3 system integrates an <strong>Auxiliary Lamp Method<\/strong> to calculate a correction factor (\u03b1):<\/p>\n<p><strong>\u03b1 = (\u03a6_aux_on_DUT_on) \/ (\u03a6_aux_on_DUT_off)<\/strong><\/p>\n<p>This factor is applied automatically in the LISUN software during <em>Photovoltaic Industry<\/em> testing where solar cells have highly non-Lambertian surfaces.<\/p>\n<p><em>Step 3: Spectral Mismatch Correction.<\/em> For <em>Lighting Industry<\/em> applications measuring SSL (Solid State Lighting) products with discontinuous SPDs, a spectral mismatch correction factor (F) is applied per CIE 127:2007.<\/p>\n<p><strong>Table 1: Calibration Uncertainty Budget for LISUN LPCE-3 System<\/strong><\/p>\n<table>\n<thead>\n<tr>\n<th style=\"text-align: left\">Error Source<\/th>\n<th style=\"text-align: left\">\u30bf\u30a4\u30d7<\/th>\n<th style=\"text-align: left\">Typical Contribution (k=2)<\/th>\n<th style=\"text-align: left\">Mitigation Method in LPCE-3<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"text-align: left\">Standard Lamp Uncertainty<\/td>\n<td style=\"text-align: left\">B<\/td>\n<td style=\"text-align: left\">\u00b10.8%<\/td>\n<td style=\"text-align: left\">NMI-certified, 2000-hour life tracking<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Sphere Coating Degradation<\/td>\n<td style=\"text-align: left\">B<\/td>\n<td style=\"text-align: left\">\u00b10.3%<\/td>\n<td style=\"text-align: left\">In-situ BaSO\u2084 reference monitor<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Stray Light (Spectrometer)<\/td>\n<td style=\"text-align: left\">\u3042<\/td>\n<td style=\"text-align: left\">\u00b10.15%<\/td>\n<td style=\"text-align: left\">Double-grating monochromator (LPCE-3)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Self-Absorption Correction<\/td>\n<td style=\"text-align: left\">\u3042<\/td>\n<td style=\"text-align: left\">\u00b10.5%<\/td>\n<td style=\"text-align: left\">Automated auxiliary lamp cycle<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\"><strong>Combined Expanded Uncertainty<\/strong><\/td>\n<td style=\"text-align: left\"><\/td>\n<td style=\"text-align: left\"><strong>\u00b11.5%<\/strong><\/td>\n<td style=\"text-align: left\"><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr \/>\n<p><strong>3. Correction Factors for Non-Ideal Source Geometries and Thermal Drift<\/strong><\/p>\n<p>Real-world DUTs\u2014such as high-power <em>Aerospace and Aviation Lighting<\/em> (e.g., LED arrays in wingtip strobes) or <em>Marine and Navigation Lighting<\/em>\u2014present distinct geometric challenges. Beam angle, color temperature, and thermal management affect measurement fidelity.<\/p>\n<p><strong>Correction for Spatial Non-Uniformity:<\/strong> The sphere\u2019s response is inherently angle-dependent near the sample port. For accurate measurement of <em>Stage and Studio Lighting<\/em> (which may exhibit beam spreads from 10\u00b0 to 120\u00b0), the LPCE-3 geometry is optimized with a cosine-corrected port baffle. A correction matrix is applied:<\/p>\n<p><strong>\u03a6_corrected = \u03a6_measured \u00d7 (I(\u03b8) \/ I_orthogonal)<\/strong><\/p>\n<p>where I(\u03b8) is the angular intensity distribution measured by the LISUN goniophotometer accessory (included in the LPCE-3 system).<\/p>\n<p><strong>Temperature Coefficient Compensation:<\/strong> <em>Photovoltaic Industry<\/em> modules and <em>Automotive Lighting Testing<\/em> (where ambient chamber temperatures can reach +85\u00b0C) require thermal drift correction. The LISUN spectroradiometer uses a built-in Peltier-cooled CCD (-10\u00b0C) to stabilize dark current. A polynomial drift correction algorithm (DTemp = T_CCD \u2013 T_ambient) is applied post-calibration.<\/p>\n<hr \/>\n<p><strong>4. Spectral Power Distribution (SPD) Analysis and Chromaticity Accuracy<\/strong><\/p>\n<p>Chromaticity coordinates (CIE 1931 x,y) derived from the SPD are highly sensitive to calibration errors in the blue (400\u2013450 nm) and far-red (650\u2013780 nm) regions.<\/p>\n<p><strong>Equation:<\/strong> X = K_m \u222b_380^780 S(\u03bb) x\u0304(\u03bb) d\u03bb<\/p>\n<p>For <em>Display Equipment Testing<\/em> (e.g., OLED panels from <em>Display Equipment Testing<\/em> rigs), the LPCE-3 employs a 1 nm spectral resolution (FWHM) to accurately resolve narrow-band emission peaks. In <em>LED &amp; OLED Manufacturing<\/em>, the color-rendering index (CRI R_a) and TM-30 metrics require fidelity in the R1\u2013R15 reference samples. The LISUN software calculates these indices with an RMS error of &lt;0.3 \u0394E_ab when calibrated per CIE 13.3-1995.<\/p>\n<p><strong>Table 2: Comparative Spectral Accuracy \u2013 LPCE-3 vs. Basic Spectroradiometer<\/strong><\/p>\n<table>\n<thead>\n<tr>\n<th style=\"text-align: left\">\u30d1\u30e9\u30e1\u30fc\u30bf<\/th>\n<th style=\"text-align: left\">LPCE-3 (LISUN)<\/th>\n<th style=\"text-align: left\">Basic Monochromator<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"text-align: left\">Spectral Resolution (FWHM)<\/td>\n<td style=\"text-align: left\">1.0 nm (0.5 nm option)<\/td>\n<td style=\"text-align: left\">2.5 nm<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Wavelength Accuracy<\/td>\n<td style=\"text-align: left\">\u00b10.3 nm<\/td>\n<td style=\"text-align: left\">\u00b10.5 nm<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Chromaticity (x,y) Reproducibility<\/td>\n<td style=\"text-align: left\">\u00b10.001<\/td>\n<td style=\"text-align: left\">\u00b10.005<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">S\/N Ratio (at 650 nm, 10ms)<\/td>\n<td style=\"text-align: left\">1000:1<\/td>\n<td style=\"text-align: left\">400:1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr \/>\n<p><strong>5. Self-Absorption Correction in High-Efficiency SSL and Laser Diode Measurements<\/strong><\/p>\n<p>Integrating sphere measurements of high-efficiency sources (( eta &gt; 150 , text{lm\/W} )) or laser diodes (LDs used in <em>Medical Lighting Equipment<\/em> \u305d\u3057\u3066 <em>Aerospace and Aviation Lighting<\/em>) face acute self-absorption errors. The DUT housing absorbs a fixed percentage of the sphere\u2019s diffuse flux, altering the sphere multiplier.<\/p>\n<p>The LISUN LPCE-3 implements a <strong>Dual-Auxiliary-Lamp Differential Method<\/strong>, which measures the flux ratio with two orthogonal auxiliary lamps. The correction factor (K_abs) is:<\/p>\n<p><strong>K_abs = (\u03a6_ref_on \/ \u03a6_ref_off) \u00d7 (1 \/ (1 \u2013 f_abs))<\/strong><\/p>\n<p>where f_abs is the absorption fraction of the DUT at a reference wavelength (e.g., 555 nm for photopic flux). This technique is mandatory for <em>Urban Lighting Design<\/em> compliance testing (e.g., EN 13032-1) where absolute flux values must be within \u00b12%.<\/p>\n<hr \/>\n<p><strong>6. System Architecture of the LISUN LPCE-3 Integrating Sphere and Spectroradiometer<\/strong><\/p>\n<p>\u305d\u306e <strong>LPCE-3 (LISUN)<\/strong> distinguishes itself through an integrated hardware-software architecture optimized for closed-loop control. The system comprises:<\/p>\n<ul>\n<li><strong>Sphere Module:<\/strong> Available in diameters of 0.3 m, 0.5 m, 1.0 m, and 2.0 m. The interior is coated with a high-diffuse reflection material (\u03c1 \u2265 96%) with a RMS surface roughness of &lt;2 \u03bcm.<\/li>\n<li><strong>Spectroradiometer:<\/strong> Equipped with a back-thinned CCD array (2048 pixels) and a Czerny-Turner optical bench. Wavelength range: 200\u20131100 nm (UV-VIS-NIR for <em>Photovoltaic Industry<\/em> \u305d\u3057\u3066 <em>Optical Instrument R&amp;D<\/em>).<\/li>\n<li><strong>Software Suite (LS-3000):<\/strong> Capable of real-time SPD visualization, flicker measurement (per IEEE 1789), and compliance reports for <em>Lighting Industry<\/em> standards (IES LM-79, CIE 84, JIS C 8157).<\/li>\n<\/ul>\n<p><strong>Table 3: LPCE-3 Specifications for Industry-Specific Testing<\/strong><\/p>\n<table>\n<thead>\n<tr>\n<th style=\"text-align: left\">\u30d1\u30e9\u30e1\u30fc\u30bf<\/th>\n<th style=\"text-align: left\">Value<\/th>\n<th style=\"text-align: left\">Relevant Industry<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"text-align: left\">Flux Measurement Range<\/td>\n<td style=\"text-align: left\">0.001 \u2013 200,000 lm<\/td>\n<td style=\"text-align: left\"><em>Automotive Lighting<\/em>, <em>Stage Lighting<\/em><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Color Temperature Range<\/td>\n<td style=\"text-align: left\">1,500 \u2013 100,000 K<\/td>\n<td style=\"text-align: left\"><em>Medical<\/em>, <em>Aerospace<\/em><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Luminous Efficacy Range<\/td>\n<td style=\"text-align: left\">0 \u2013 350 lm\/W<\/td>\n<td style=\"text-align: left\"><em>LED &amp; OLED Manufacturing<\/em><\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Measurement Speed (Full Scan)<\/td>\n<td style=\"text-align: left\">&lt; 3 seconds<\/td>\n<td style=\"text-align: left\"><em>Display Equipment Testing<\/em><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr \/>\n<p><strong>7. Comparative Analysis: LPCE-3 versus Secondary Standards and Goniophotometry<\/strong><\/p>\n<p>While goniophotometry provides angular distribution data, it is spatially inefficient for total flux measurements. The integrating sphere method is faster and exhibits lower uncertainty for total luminous flux when combined with a calibrated spectroradiometer.<\/p>\n<p><strong>Matrix comparing LPCE-3 to Goniophotometer for <em>Automotive Lighting Testing<\/em>:<\/strong><\/p>\n<table>\n<thead>\n<tr>\n<th style=\"text-align: left\">Attribute<\/th>\n<th style=\"text-align: left\">LPCE-3 (Sphere)<\/th>\n<th style=\"text-align: left\">\u30b4\u30cb\u30aa\u30d5\u30a9\u30c8\u30e1\u30fc\u30bf\u30fc<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"text-align: left\">Measurement Time<\/td>\n<td style=\"text-align: left\">20 s (single position)<\/td>\n<td style=\"text-align: left\">&gt;45 min (full scan)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Photometric Error (for direct emission)<\/td>\n<td style=\"text-align: left\">\u00b11.5%<\/td>\n<td style=\"text-align: left\">\u00b11.2% (geometric)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Colorimetric Data<\/td>\n<td style=\"text-align: left\">Simultaneous (SPD)<\/td>\n<td style=\"text-align: left\">Post-process (angular)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left\">Lab Footprint<\/td>\n<td style=\"text-align: left\">1.5 m\u00b2 (0.5 m sphere)<\/td>\n<td style=\"text-align: left\">6 m\u00b2 + dark room<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The LPCE-3 superiority is evident in <em>Scientific Research Laboratories<\/em> where rapid prototyping requires iterative spectral analysis.<\/p>\n<hr \/>\n<p><strong>8. Standards Compliance and Industry-Specific Testing Frameworks<\/strong><\/p>\n<p>The LPCE-3 system is pre-configured to meet:<\/p>\n<ul>\n<li><strong>IES LM-79-19:<\/strong> Electrical and photometric measurements of SSL products.<\/li>\n<li><strong>CIE S 025\/E:2015:<\/strong> Test method for LED lamps, luminaires, and modules.<\/li>\n<li><strong>IEC 62471 (Photobiological Safety):<\/strong> Including blue light hazard (LB) and retinal thermal hazard (LR).<\/li>\n<li><strong>SAE J1889 (Automotive):<\/strong> For headlamp and signal light flux measurement.<\/li>\n<li><strong>FAA AC 20-74 (Aviation):<\/strong> For aircraft position and anti-collision lights.<\/li>\n<\/ul>\n<p>In <em>Marine and Navigation Lighting<\/em>, the system\u2019s ability to measure strobe intensity over a 1-ms integration window is critical for IALA compliance.<\/p>\n<hr \/>\n<p><strong>9. FAQ Section<\/strong><\/p>\n<p><strong>Q1: How does the LPCE-3 handle flicker measurement for Medical Lighting Equipment?<\/strong><br \/>\nThe LPCE-3 includes a high-speed flicker module (up to 20 kHz) that captures temporal light modulation per IEEE 1789-2015. This is essential for surgical lighting and endoscopy equipment where flicker can induce operator fatigue.<\/p>\n<p><strong>Q2: What is the recommended recalibration interval for the sphere coating?<\/strong><br \/>\nLISUN recommends a full photometric recalibration every 12 months. However, for <em>Photovoltaic Industry<\/em> users testing under UV exposure (200\u2013400 nm), a biannual spectroscopic calibration is advised due to potential coating degradation.<\/p>\n<p><strong>Q3: Can the LPCE-3 measure absolute spectral irradiance (W\/m\u00b2\/nm) for Urban Lighting Design?<\/strong><br \/>\nYes. The spectroradiometer can be configured for irradiance measurement by using the cosine-corrected head accessory. This allows precise measurement of Lux levels and spectral irradiance distribution for street lighting design compliance (e.g., EN 13201).<\/p>\n<p><strong>Q4: How does the system correct for sphere-to-DUT distance errors in Automotive Lighting Testing?<\/strong><br \/>\nThe LPCE-3 standard includes an auxiliary lamp fixture with a built-in distance sensor. The software compensates for distance variances based on the inverse-square law, maintaining &lt;0.3% error for headlamp measurements at distances from 0.5 m to 2.0 m.<\/p>\n<p><strong>Q5: What data output formats are supported for Display Equipment Testing?<\/strong><br \/>\nThe LS-3000 software exports data in .xlsx, .csv, and .cie formats. It also provides TM-30-18, CQS, and CRI color rendering metrics, as well as chromaticity coordinates (x,y,u\u2019,v\u2019) required for LCD and OLED panel certification.<\/p>","protected":false},"excerpt":{"rendered":"<p>Technical White Paper: Precision Integrating Sphere Design and Calibration for High-Fidelity Photometric, Colorimetric, and Radiometric Measurement Publication Classification: Optical Metrology and Instrumentation Target Audience: R&amp;D Engineers, Quality Assurance Specialists, Standards Compliance Officers, Laboratory Managers Revision Status: V2.1 \u2013 Updated for LPCE-3 (LISUN) System Integration 1. Foundational Geometry and Optical Theory of the Integrating Sphere The integrating sphere functions as an optical diffuser with a high-reflectance Lambertian coating, designed to spatially integrate radiant flux from a source. For accurate total luminous flux (\u03a6_v) measurement, the sphere must adhere to the principle of a uniform radiance distribution across its interior surface. The fundamental design equation governing sphere throughput is the sphere multiplier [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3432,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[948],"class_list":["post-8843","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blogs","tag-small-integrating-sphere"],"_links":{"self":[{"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/posts\/8843","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/comments?post=8843"}],"version-history":[{"count":1,"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/posts\/8843\/revisions"}],"predecessor-version":[{"id":8844,"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/posts\/8843\/revisions\/8844"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/media\/3432"}],"wp:attachment":[{"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/media?parent=8843"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/categories?post=8843"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ledtestsystem.com\/ja\/wp-json\/wp\/v2\/tags?post=8843"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}