Integrating Sphere Fundamentals and Applications

Introduction

The photoreceptor cells on the retina of the human eye are divided into two types: rod-shaped (circle) cells and cone-shaped (round) cells. The former has high sensitivity and is used to sense low light and distinguish light and dark, but it has no color perception. Cone-shaped (round) cells have low sensitivity and are used to sense strong light and have color perception. The sensitivity of photoreceptor cells to different wavelengths is different, and the sensitivity of cone cells is the highest at 555nm, which is called spectral optical efficiency V(λ). The relationship between photometric and radiometric: photometric (λ) = Km · V (λ) · radiometric (λ) Km = 683lm · W-1. 

Luminous flux

The size of the part of the light radiation flux (power) that can be felt by the human visual system, the unit is lm. The luminous flux of a light source is the sum of the light intensities emitted by the light source in all directions in space. Its schematic diagram is as follows:

The luminous flux of the light source

Light intensity

The luminous flux dΦ emitted by a light source in a solid angle element containing this direction in a given direction is divided by the solid angle element dΩ, in candela cd. Its schematic diagram is as follows:

Light intensity

Illumination

The illuminance at a point on a surface is the quotient of the luminous flux incident on the bin containing the point divided by the area of the bin. The metric unit of illuminance is lx (lm/m2).

Illumination

Luminance

The brightness of a point on the light-emitting surface of the light source is the quotient of the luminous intensity of the surface element in a given direction divided by the orthographic projection area of the surface element on a plane perpendicular to the given direction, and the unit is cd/m2.

Luminance

Color temperature, correlated color temperature

When the color of light emitted by a light source is exactly the same as the color of light radiated by a black body at a certain temperature, the temperature of the black body is called the color temperature of the light source, and the unit is K. For most artificial light sources, the color of light emitted by it cannot be exactly the same as the color of light radiated by a black body at a certain temperature, so it cannot be represented by color temperature. The correlated color temperature is used to represent, that is, when the light emitted by the light source is closest to the color of the light radiated by the black body at a certain temperature, the temperature of the black body is called the correlated color temperature of the light emitted by the light source, and the unit is K.

Dominant wavelength, color purity

Any color can be regarded as a color that is matched by mixing a certain spectral color with a reference light source in a certain proportion. This spectral color is the dominant wavelength of the color. If the chromaticity coordinates of the measured light source have been obtained, then on the CIE1931 chromaticity diagram, a straight line is drawn from the color coordinate point of the E light source to the color coordinate point of the measured light source, and the wavelength value where the extended straight line intersects the spectral locus is called is the dominant wavelength of the measured light source. Generally, only the color coordinate point of the measured light source is adjacent to the spectral locus. The degree to which the color of the sample is close to the spectral color of the dominant wavelength indicates the purity of the color of the sample, expressed as a percentage.

color purity

Color rendering and color rendering index

The color of the object seen by the human eye under different light sources will change, and the color of the object will be distorted. This characteristic that affects the color of the object is called the color rendering of the light source. Under the illumination of a light source with good color rendering, the color distortion of the object is small. In 1974, CIE recommended the “test color” method to quantitatively evaluate the color rendering of light sources. Color rendering, expressed by a color rendering index. CIE stipulates that a complete radiator is used as a reference light source, and the color rendering index is set to 100, and a total of 14 kinds of standard samples for testing (15 kinds in China) are specified.

Frequency

Frequency refers to the light output frequency of the lighting product to be tested.

Flicker index

The flicker index is expressed as the area above the average level of light output divided by the total area of the light output waveform in one cycle of the light output of the lighting product, i.e.

Flicker percentage and modulation depth

The flicker index is expressed as the area above the average level of light output divided by the total area of the light output waveform in one cycle of the light output of the lighting product, i.e.

Flicker percentage

LISUN Solution

Solution 1 (It is suitable for the Middle & Small Manufactory or General Test Lab)

System Configuration:High Precision CCD Spectroradiometer (LMS-9000C), Optical Fiber (CFO-1.5M), Digital Power Meter(LS2050B/LS2050C/LS2012), DC Power Source (DC Series), AC Power Source (LSP-500VARC or LSP-500VARC-Pst), Integrating Sphere (IS-1.5MA and IS-0.3M), Standard Light Source (SLS-50W and SLS-10W), 19 Inch Cabinet(CASE-19IN). You can download the detail PDF here: LPCE-2 (LMS-9000C) High Precision CCD Spectroradiometer Integrating Sphere System Brochure

LPCE-2 Integrating Sphere Spectroradiometer LED Testing System is for single LEDs and LED lighting products light measurement. LED’s quality should be tested by checking its photometric, colorimetric and electrical parameters. According to CIE 177, CIE84,  CIE-13.3, IES LM-79-19, Optical-Engineering-49-3-033602, COMMISSION DELEGATED REGULATION (EU) 2019/2015, IESNA LM-63-2 and ANSI-C78.377, it recommends to using an array spectroradiometer with an integrating sphere to test SSL products. The LPCE-2 system is applied with LMS-9000C High Precision CCD Spectroradiometer or LMS-9500C Scientific Grade CCD Spectroradiometer, and A molding integrating sphere with holder base. This sphere is more round and the test result is more accruacy than the traditional integrating sphere.

LPCE-2(LMS-9000)High Precision Spectroradiometer Integrating Sphere System

Measures:
• Colorimetric: Chromaticity coordinates, CCT, Color Ratio, Peak Wavelength, Half Bandwidth, Dominant Wavelength, Color Purity, CRI, CQS, TM-30 (Rf, Rg), Spectrum Test
• Photometric: Luminous Flux, Luminous Efficiency, Radiant Power, EEI, Energy Efficiency Class, Pupil Flux, Pupil Flux Efficiency, Pupil Factor, Cirtopic Flux, Plant Growth Lamp PAR and PPF
• Electrical: Voltage, Current, Power, Power Factor, Displacement Factor, Harmonic
• LED optical maintenance test: Flux VS time, CCT VS time, CRI VS time, Power VS time, Power Factor VS time, Current VS time and Flux Efficiency VS time.

Solution 2(Suitable for most LED factories and customers with insufficient budget)

The Sphere System Configuration: 
CCD Spectroradiometer (LMS-7000), Optical Fiber (CFO-1.5M), Digital Power Meter (LS2008R), DC Power Source (DC-S Series), AC Power Source (LSP-500VAS), Integrating Sphere (IS-1.5MA-CASE and IS-0.3M), Standard Light Source (SLS-50W and SLS-10W)

LPCE-3 is a CCD Spectroradiometer Integrating Sphere Compact System for LED Testing. It is suitable for single LED and LED luminaires’ photometric, colorimetric and electrical measurement. The measured data meets the requirements of CIE 177, CIE84,  CIE-13.3, COMMISSION DELEGATED REGULATION (EU) 2019/2015, IES LM-79-19, Optical-Engineering-49-3-033602, IESNA LM-63-2, ANSI-C78.377 and GB standards

LPCE-3_ CCD Spectroradiometer Integrating Sphere Compact System

Measurement:
• Colorimetric: Chromaticity coordinates, CCT, Color Ratio, Peak Wavelength, Half Bandwidth, Dominant Wavelength, Color Purity, CRI (Ra, R1 to R15), Spectrum Test, TM30 (Rf, Rg), CQS
• Photometric: Luminous Flux, Luminous Efficiency, Radiant Power, EEI, PAR, PPF
• Electrical: Voltage, Current, Power, Power Factor, Harmonic (Optional)

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

Our main products are Goniophotometer, Integrating Sphere, Spectroradiometer, Surge Generator, ESD Simulator Guns, EMI Receiver, EMC Test Equipment, Electrical Safety Tester, Environmental Chamber, Temperature Chamber, Climate Chamber, Thermal Chamber, Salt Spray Test, Dust Test Chamber, Waterproof Test, RoHS Test (EDXRF), Glow Wire Test and Needle Flame Test.

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