Introduction to Integrating Sphere Theory and Design

Integrating spheres are fundamental optical devices used for precise photometric, radiometric, and colorimetric measurements. Their spherical geometry ensures uniform light diffusion, enabling accurate assessments of total luminous flux, reflectance, transmittance, and spectral power distribution. The principle relies on multiple internal reflections, where incident light undergoes diffuse scattering, creating a spatially uniform radiance distribution.

A high-quality integrating sphere consists of a hollow spherical cavity coated with a highly reflective, spectrally neutral material such as barium sulfate (BaSO₄) or polytetrafluoroethylene (PTFE). The sphere’s interior surface must exhibit near-Lambertian reflectance characteristics to minimize directional bias. Ports for light entry, sample placement, and detector mounting are strategically positioned to avoid direct illumination of the detector, ensuring measurement integrity.

Key Applications of UV-VIS Integrating Spheres

Integrating spheres serve critical functions across multiple industries where precise light measurement is essential:

• Lighting Industry: Measurement of total luminous flux (in lumens) for LED lamps, HID, and fluorescent sources.
• LED & OLED Manufacturing: Spectral efficiency analysis, color rendering index (CRI), and correlated color temperature (CCT) validation.
• Automotive Lighting Testing: Compliance with ECE, SAE, and FMVSS standards for headlamps, taillights, and signal lamps.
• Aerospace and Aviation Lighting: Certification of cockpit displays, navigation lights, and emergency illumination.
• Display Equipment Testing: Evaluation of LCD, OLED, and micro-LED panels for luminance uniformity and color gamut.
• Photovoltaic Industry: Quantum efficiency measurements of solar cells and modules.
• Optical Instrument R&D: Calibration of spectrometers, photometers, and radiometers.
• Scientific Research Laboratories: Material reflectance/transmittance studies and biophotonic applications.
• Urban Lighting Design: Optimization of street lighting systems for energy efficiency and visual comfort.
• Marine and Navigation Lighting: Compliance with IMO and COLREG regulations.
• Stage and Studio Lighting: Spectral consistency and flicker analysis for high-end production lighting.
• Medical Lighting Equipment: Validation of surgical and diagnostic light sources.

LISUN LPCE-2/LPCE-3 Integrating Sphere Spectroradiometer System

The LISUN LPCE-2/LPCE-3 is a high-precision spectroradiometer system designed for comprehensive photometric and colorimetric testing. It integrates a UV-VIS-NIR spectrometer with a calibrated integrating sphere, ensuring compliance with international standards such as CIE 177, IES LM-79, and EN 13032-1.

Technical Specifications

Testing Principles

1. Total Luminous Flux Measurement:
   The light source is placed inside or at the entry port of the sphere. The detector captures the spatially averaged radiance, which is converted to luminous flux using a calibrated reference lamp.

2. Spectral Power Distribution (SPD):
   The spectrometer resolves the emitted spectrum, enabling CCT, CRI, and peak wavelength determination.

3. Reflectance/Transmittance Analysis:
   Samples are mounted at the sphere’s sample port, and incident light is compared with reflected/transmitted light to derive optical properties.

Competitive Advantages

• High Uniformity (>98%): Minimizes spatial error in flux measurements.
• NIR Extension (LPCE-3): Supports photovoltaic and automotive IR LED testing.
• Automated Calibration: Reduces operator-dependent errors.
• Multi-Standard Compliance: Meets LM-79, CIE 177, and EN 13032-1 requirements.

Industry-Specific Use Cases

1. LED & OLED Manufacturing

The LPCE-3’s extended NIR range allows for efficiency testing of IR LEDs used in biometric sensors and automotive LiDAR. Its high-resolution spectrometer ensures accurate CRI and CQS calculations for display backlighting.

2. Automotive Lighting Testing

Compliance with UNECE R128 and SAE J578 mandates precise luminous intensity and chromaticity measurements. The LPCE-3’s ±2% flux accuracy ensures reliable certification of adaptive headlamp systems.

3. Photovoltaic Industry

Quantum efficiency (QE) measurements require NIR sensitivity. The LPCE-3’s 1050nm range facilitates spectral response analysis of perovskite and multi-junction solar cells.

4. Medical Lighting Validation

Surgical LED lights must meet DIN 5035-7 and ISO 15004-2 standards. The LPCE-2’s UV-VIS range verifies spectral output for ophthalmology and dermatology applications.

Scientific Data and Standards Compliance

• CIE 177:2007 – LED measurement accuracy guidelines.
• IES LM-79-19 – Electrical and photometric testing of solid-state lighting.
• ISO 19476:2016 – Reflectance standards for integrating spheres.

FAQ Section

Q1: What is the difference between LPCE-2 and LPCE-3?
The LPCE-3 extends into the NIR spectrum (up to 1050nm), making it suitable for photovoltaic and IR LED testing, whereas the LPCE-2 is optimized for UV-VIS applications (380–780nm).

Q2: How often should the integrating sphere be recalibrated?
Recalibration is recommended every 12 months or after 500 hours of continuous use, whichever comes first.

Q3: Can the LPCE-3 measure pulsed light sources?
Yes, the system supports pulsed light analysis with a minimum integration time of 1ms.

Q4: What is the maximum sample size for reflectance testing?
The sample port accommodates up to 100mm diameter samples, with larger custom configurations available.

Q5: Does the system support multi-channel spectral analysis?
Yes, the LPCE-3 can integrate with auxiliary spectrometers for simultaneous UV-VIS-NIR measurements.