Research on Color Temperature Measurement Technology and Application Based on LISUN LMS-6000 Handheld CCD Spectroradiometer

Abstract:
Color temperature is a core photometric and colorimetric parameter in the fields of lighting sources, display devices, horticultural lighting, and healthy lighting. Accurately measure color temperature directly determines the lighting quality, visual comfort, and photobiological safety of products. This paper takes the LISUN LMS-6000 series handheld CCD spectroradiometer as the research object, systematically expounds the principle, technical specifications, multi-model adaptability, test methods, and engineering applications to measure color temperature. Combined with measured data and standard specifications, it verifies the reliability of this series of instruments in fast and high-precision measure color temperature on site, providing a technical reference for color temperature detection and quality control in the lighting and display industries.

1. Introduction
In scenarios such as LED lighting, backlight displays, film and television lighting, plant factories, and medical lighting, color temperature (CCT) is a key indicator describing the color of light sources, which directly affects visual perception, color reproduction, physiological rhythm, and product consistency. Traditional methods to measure color temperature rely on benchtop spectroradiometers or integrating sphere systems, which have limitations such as large size, complex wiring, and difficulty in on-site deployment. Handheld CCD spectroradiometers have become the mainstream solution for on-site measure color temperature due to their advantages of portability, speed, and simultaneous multi-parameter testing.

The LISUN LMS-6000 series portable spectroradiometer adopts a long-focus cross asymmetric CT spectroscopic system and high-sensitivity CCD array, enabling high-precision spectral collection in the visible and extended bands. It supports to measure color temperature, chromaticity coordinates, color rendering index, TM-30, illuminance, luminance, blue light hazard, flicker, horticultural lighting parameters, etc., covering full-scene requirements to measure color temperature. Compliant with CIE-13.3, CIE-177, GB/T 20145 and other domestic and international standards, it provides an integrated solution for measure color temperature in engineering sites and laboratories.

2. Basic Principle to Measure Color Temperature
Color temperature is based on the theory of blackbody radiation. The light color of an ideal blackbody under thermal radiation gradually changes from red → yellow → white → blue with temperature, and this temperature is defined as color temperature in Kelvin (K). Most actual light sources are non-blackbodies, so Correlated Color Temperature (CCT) is used for characterization: in the CIE 1960 UCS uniform chromaticity diagram, the temperature corresponding to the closest point from the light source chromaticity coordinate to the blackbody locus is the correlated color temperature.

The core process to measure color temperature:
• Collect the Spectral Power Distribution (SPD) of the light source in 380–780 nm (or extended bands);
• Calculate tristimulus values X, Y, Z according to the CIE standard observer function, and derive chromaticity coordinates (x, y) or (u’, v’);
• Match the blackbody locus and isotherms to calculate CCT and blackbody deviation Duv;
• Synchronously output parameters such as color rendering index CRI, TM-30, color tolerance, and spectrogram.

The LMS-6000 has a built-in professional colorimetric algorithm that automatically completes the whole process to measure color temperature and outputs stable results within 1 second, meeting the needs of rapid testing.

3. Core Performance and Model Configuration of LMS-6000 Series to Measure Color Temperature
3.1 Core Technical Specifications (Special Indexes to Measure Color Temperature)

Parameter Item	Index Value	Significance for Measuring Color Temperature
Wavelength Range	380–780 nm (standard); 350–800/950 nm (extended)	Covers the full visible band to ensure the integrity of color temperature calculation
Wavelength Accuracy	±0.5 nm	Reduces color temperature errors caused by spectral shift
Chromaticity Coordinate Accuracy	Δx, Δy ±0.005	Directly determines the accuracy to measure color temperature
Color Temperature Range	1500 K ~ 100000 K	Covers the full range of warm white, neutral white, cool white, and special light sources
Color Temperature Accuracy	±0.6%	High precision meets certification and production line quality control
Photometric Linearity	±0.6%	Stable performance to measure color temperature under strong/weak light
Stray Light	<0.015% (600 nm); <0.03% (435 nm)	Suppresses stray light and improves color temperature accuracy at low illuminance
Integration Time	0.1 ms – 5 s	Adapts to measure color temperature of light sources with different brightness

3.2 LMS-6000 Series Models and Adaptability to Measure Color Temperature

Model	Wavelength Range	Ability to Measure Color Temperature	Extended Functions	Application Scenarios
LMS-6000	380–780 nm	Standard high-precision CCT, Duv, chromaticity coordinates	CRI, TM-30, spectrogram	General lighting measure color temperature
LMS-6000C	380–780 nm	Basic CCT, Duv, chromaticity coordinates	No TM-30/PC software	Economic on-site sampling inspection
LMS-6000F	380–780 nm	Standard CCT measurement	Flicker test	Color temperature + flicker of dimmable light sources
LMS-6000L	380–780 nm	High-precision CCT	Luminance test	Display/panel measure color temperature
LMS-6000B	350–800 nm	Compatible with CCT + blue light hazard	Retinal blue light hazard	Healthy lighting color temperature detection
LMS-6000P	350–850 nm	CCT + horticultural lighting parameters	PAR, PPFD	Horticultural lamps measure color temperature
LMS-6000S	350–950 nm	CCT + blue light hazard + horticultural parameters	Full-band spectrum	High-end lighting/scientific research
LMS-6000TLCI	380–780 nm	Professional CCT measurement	TLCI for film & television	Film and television lighting measure color temperature

4. Test Methods and Procedures of LMS-6000 to Measure Color Temperature
4.1 Standard Test Conditions
• Environment: No direct light or reflection interference, temperature 25±2℃, relative humidity 45%–75%;
• Light source preheating: LED ≥ 30 min, fluorescent lamp ≥ 15 min, to reach thermal stability;
• Instrument calibration: Calibrated with standard A light source to ensure traceable results to measure color temperature.

4.2 Measurement Steps
• Power on and preheat for 3–5 minutes, enter the color temperature/spectrum test mode;
• Calibrate dark current and optical standard to eliminate system errors;
• Align the probe vertically to the center of the light source, with an adjustable distance of 5–50 cm to avoid spot overflow;
• Automatic integration, obtain spectrum, CCT, Duv, x/y coordinates within 1 second;
• Measure 3 times continuously and take the average, save data and spectrogram;
• Export to PC software to generate reports, supporting CIE 1931/1976 chromaticity diagram and color tolerance analysis.

4.3 Example Data to Measure Color Temperature (Typical LED Light Sources)

Light Source Type	Nominal Color Temperature	Measured CCT (K)	Duv	Chromaticity Coordinate x	Chromaticity Coordinate y	Ra	Judgment
Warm White LED	3000 K	2986	0.0012	0.4352	0.4012	95.2	Qualified
Neutral White LED	4000 K	4015	-0.0008	0.3825	0.3768	96.5	Qualified
Cool White LED	6500 K	6489	0.0021	0.3128	0.3305	94.8	Qualified

The results show that the error of LMS-6000 to measure color temperature is <1%, meeting the requirements of GB/T 39394, CIE-15 and other standards.

5. Engineering Applications of LMS-6000 to Measure Color Temperature

5.1 Lighting Production Line Quality Control
Batch measure color temperature to quickly screen products with color difference, ensure color temperature consistency of the same batch, and reduce defective rate.

5.2 On-Site Acceptance and Inspection
Quickly measure color temperature in shopping malls, schools, hospitals, stadiums and other places to verify compliance with design and health standards.

5.3 Display and Backlight Testing
LMS-6000L synchronously measure color temperature and luminance, suitable for color calibration of screens, TVs and vehicle-mounted displays.

5.4 Healthy and Film & Television Lighting
LMS-6000B/BF measure color temperature + blue light hazard; LMS-6000TLCI meets dual tests of color temperature and TLCI for film and television lighting.

5.5 Horticultural Lighting R&D
LMS-6000P/S measure color temperature + PPFD/PAR/YPFD to optimize spectral ratio and improve light energy utilization.

6. Advantages and Conclusion
6.1 Core Advantages
High Precision: Color temperature accuracy ±0.6%, chromaticity coordinates ±0.005, meeting certification-level measure color temperature;
Full Scenarios: Multiple models cover needs to measure color temperature in general, health, film and television, horticulture, industry and other fields;
Portable and Efficient: Handheld design, 5-inch touch screen, 4000 mAh long battery life, instant measurement on site;
Standard Compliance: Compliant with CIE, IEEE, GB/T series standards, reports can be directly used for testing and certification.

6.2 Conclusion
With advanced optical system, stable CCD detection and professional colorimetric algorithm, the LISUN LMS-6000 series handheld CCD spectroradiometer realizes high precision, high efficiency and high adaptability to measure color temperature. It can simultaneously output spectrum, illuminance, color rendering index, TM-30, blue light hazard, flicker, horticultural parameters and more, solving the pain points of inconvenient on-site use and single function of traditional equipment. In the fields of lighting, display, health, horticulture, film and television, this instrument is an ideal tool for measure color temperature and photometric color quality control, providing a standardized, portable and integrated testing solution for the industry.

Tags：LMS-6000