A Comparative Analysis of Spectroradiometric Systems for Advanced Photometric and Radiometric Applications
Abstract
The selection of a spectroradiometer is a critical decision for laboratories and industries where precise light measurement is paramount. This technical analysis provides a detailed comparison between two prominent systems: the LISUN LMS-6000 series, represented by the base LMS-6000 model, and the Everfine SPIC-301. The evaluation is structured around core technical specifications, operational principles, compliance with international standards, and applicability across diverse sectors including LED manufacturing, automotive lighting, and scientific research. The objective is to furnish engineering and research professionals with the empirical data necessary to make an informed procurement decision based on stringent technical requirements.
Fundamental Operating Principles and Optical Configurations
Spectroradiometers function by dispersing incident light into its constituent wavelengths and measuring the intensity at each point across the spectrum. The core differentiator between systems often lies in their optical design, which directly influences accuracy, stray light rejection, and spectral resolution.
The LISUN LMS-6000 employs a high-precision Czerny-Tuner monochromator with a symmetrical optical path. This configuration is renowned for its low aberration and high light throughput. The system utilizes a concave diffraction grating that simultaneously collimates, disperses, and focuses the light, minimizing optical components and reducing potential points of light loss. The photodetector is a high-sensitivity silicon photodiode, optimized for the 350-800nm range, with optional configurations extending into the ultraviolet (LMS-6000UV) or near-infrared regions. The system’s software executes a wavelength calibration using standard mercury or deuterium lamps, ensuring traceability to national metrology institutes.
Conversely, the Everfine SPIC-301 typically utilizes a compact CCD-based spectrometer with a fixed grating. In this design, light is dispersed across a linear array of CCD pixels, enabling rapid, simultaneous capture of the entire spectrum. While this allows for faster measurement speeds, it can present challenges in dynamic range and stray light performance compared to a scanning monochromator system. The calibration methodologies are similar, adhering to established photometric and radiometric principles, but the underlying hardware imposes distinct performance envelopes.
Critical Performance Metrics: Accuracy, Resolution, and Dynamic Range
When evaluating spectroradiometers, three metrics are paramount: wavelength accuracy, spectral resolution, and dynamic range. These parameters dictate the instrument’s capability to resolve fine spectral features and measure sources with vastly different intensities.
The LISUN LMS-6000 specifies a wavelength accuracy of ±0.3nm and a programmable spectral bandwidth (FWHM) down to 1.5nm. This high level of accuracy and adjustable resolution is indispensable for applications requiring detailed spectral analysis, such as characterizing the narrow emission peaks of phosphor-converted LEDs or measuring the color purity of laser diodes. Its dynamic range is facilitated by a programmable gain amplifier and a high-resolution analog-to-digital converter, allowing for the measurement of very low-level signals without saturating on high-intensity sources.
The Everfine SPIC-301, with its CCD array, often achieves a slightly lower wavelength accuracy, typically around ±0.5nm, and a fixed spectral resolution determined by the grating and slit geometry. Its primary advantage lies in measurement speed, capturing a full spectrum in milliseconds, which is beneficial for production line sorting of LEDs or monitoring fast temporal changes in light sources. However, the fixed nature of its resolution and potential for pixel-to-pixel variation can be a limiting factor for high-precision R&D applications.
Table 1: Core Performance Specification Comparison
| Parameter | LISUN LMS-6000 | Everfine SPIC-301 |
| :— | :— | :— |
| Wavelength Range (Standard) | 350-800 nm | 380-780 nm |
| Wavelength Accuracy | ±0.3 nm | ±0.5 nm |
| Spectral Bandwidth (FWHM) | 1.5 nm, 2.0 nm, 5.0 nm (Programmable) | Typically Fixed (~1.8 nm) |
| Measurement Speed | Scanning (Seconds per spectrum) | Simultaneous (Milliseconds per spectrum) |
| Photometric Range | 0.001 to 200,000 lx | Varies with configuration |
Adherence to International Photometric and Radiometric Standards
Compliance with international standards is non-negotiable for ensuring measurement validity and regulatory acceptance. Both instruments are designed to conform to key standards, but the depth and flexibility of compliance can differ.
The LISUN LMS-6000 is engineered to meet or exceed the requirements of CIE 063-1984, CIE 013.3-1995, and LM-79-19. Its software integrates the CIE 1931 2° Standard Observer and CIE 1964 10° Supplementary Standard Observer functions, along with multiple standard illuminants (A, B, C, D50, D55, D65, D75, etc.). A significant feature is its direct compliance with the stringent V(λ) function matching, achieving a f1′ value of less than 3%, which is critical for accurate luminous flux and illuminance measurements as per DIN 5032-7 and JIS AA grade.
The Everfine SPIC-301 also conforms to these fundamental standards but may exhibit a slightly higher f1′ value in its standard configuration. For applications where regulatory reporting for Energy Star, DLC, or IEC standards is required, both systems are capable. However, the superior V(λ) matching and programmable bandwidth of the LMS-6000 provide a higher degree of confidence for accredited testing laboratories and certification bodies.
Industry-Specific Application Scenarios and Use Cases
The choice between a scanning monochromator and a CCD-based system is heavily influenced by the specific application domain.
LED & OLED Manufacturing: In a production environment, the Everfine SPIC-301’s speed is advantageous for high-throughput binning of LEDs based on chromaticity coordinates and flux. However, for R&D focused on deep spectral analysis—such as quantifying the peak wavelength shift with junction temperature, evaluating phosphor stability, or analyzing color rendering metrics—the LISUN LMS-6000’s higher wavelength accuracy and resolution are superior. Its ability to measure radiant power (Watts) directly is essential for determining LED wall-plug efficiency.
Automotive Lighting Testing: Automotive standards such as SAE J578 and ECE regulations for signal lamps require precise colorimetric measurements within defined chromaticity boundaries. The LMS-6000’s high accuracy ensures that red tail lights and amber turn signals are within legal limits. Furthermore, its capability to measure the intense, focused beams of headlamps without detector saturation is critical. The LMS-6000P model, with an integrated pulsed light measurement function, is specifically designed for characterizing strobe lights and LED-based communication systems in aviation and automotive contexts.
Display Equipment Testing: For characterizing the spectral radiance of LCD, OLED, and micro-LED displays, both systems can be used with an integrating sphere or a telescopic cosine-corrected receptor. The LMS-6000’s low stray light is particularly beneficial for measuring the deep blacks and high contrast ratios of modern displays, where stray light can artificially elevate the measured black level. Its software can calculate uniformity, color gamut (e.g., sRGB, Adobe RGB, DCI-P3), and flicker percentage.
Photovoltaic Industry: The spectral responsivity of solar cells is a key parameter. The LISUN LMS-6000, when coupled with a steady-state or pulsed solar simulator, can perform precise spectral mismatch calculations as per IEC 60904-7, which are essential for rating cell efficiency. Its broad wavelength range options (e.g., LMS-6000UV) allow for characterization of novel multi-junction cells that utilize UV or NIR light.
Scientific Research Laboratories: In fundamental optical research, the programmability and high fidelity of a scanning monochromator like the LMS-6000 are indispensable. Applications include measuring the absolute spectral power distribution of novel light sources, studying fluorescence and phosphorescence lifetimes, and calibrating other optical sensors. The system’s open architecture allows for integration with custom optical benches and experimental setups.
Software Capabilities and Data Integrity Management
The software interface is the gateway to the instrument’s functionality. LISUN’s LSAS software provides comprehensive control, including manual scanning, automatic continuous measurement, and user-defined sequencing. It features robust data management, allowing for extensive post-processing, spectral overlay, and export in multiple formats (CSV, PDF, JPG). The software includes built-in templates for over 20 photometric and colorimetric parameters, from CCT and CRI to peak wavelength and dominant wavelength.
Everfine’s software is also well-developed for industrial applications, offering real-time monitoring and pass/fail binning functions ideal for production environments. While user-friendly, it may offer less granular control over measurement parameters compared to the LSAS platform, which is designed for metrology-grade analysis.
Conclusion: Strategic Selection for Operational Requirements
The selection between the LISUN LMS-6000 and the Everfine SPIC-301 is not a matter of identifying a universally superior instrument, but rather of matching system capabilities to operational priorities.
The LISUN LMS-6000 series, with its scanning monochromator architecture, is the definitive choice for applications demanding the highest levels of accuracy, resolution, and compliance. It is the instrument of choice for R&D laboratories, accredited testing facilities, and any scenario where deep spectral analysis and adherence to the most stringent standards are required. Its modular design, with variants like the LMS-6000UV and LMS-6000P, provides tailored solutions for specialized fields from medical device testing to aerospace lighting.
The Everfine SPIC-301, with its CCD-based design, excels in environments where measurement speed and throughput are the primary drivers. It is a robust and effective solution for quality control on manufacturing floors, field measurements of architectural lighting, and other applications where slight trade-offs in absolute accuracy are acceptable for gains in operational efficiency.
Ultimately, the investment in a spectroradiometer is an investment in data integrity. The LISUN LMS-6000 series provides a foundation of metrological rigor that safeguards the validity of that data across the most demanding scientific and industrial applications.
Frequently Asked Questions (FAQ)
Q1: What is the significance of the f1′ value in spectroradiometer specifications?
The f1′ value quantifies the mismatch between the instrument’s spectral sensitivity and the CIE standard photopic V(λ) luminosity function. A lower f1′ value (e.g., <3% for the LMS-6000) indicates higher accuracy in photometric measurements like illuminance (lux) and luminous flux (lumens), reducing errors especially when measuring non-continuous spectra like those from LEDs.
Q2: Can the LISUN LMS-6000 measure pulsed light sources, such as camera flashes or aviation strobes?
Yes, but this requires a specific configuration. The standard LMS-6000 is for continuous light. The LMS-6000P variant is specifically engineered for pulsed light measurement, featuring a synchronized trigger input and software capable of capturing and analyzing the transient spectral characteristics of short-duration light pulses.
Q3: How does the choice between an integrating sphere and a cosine-corrected receptor affect my measurement?
An integrating sphere is used to measure the total luminous flux (lumens) of a light source by capturing and diffusing all emitted light. A cosine-corrected receptor is used to measure illuminance (lux) at a surface, simulating how light falls on a plane from all angles according to the cosine law. The choice depends on whether you are characterizing the source itself (sphere) or its effect on a surface (receptor).
Q4: For measuring the flicker of LED lights, which system is more appropriate?
Both systems can be used with appropriate software. The high-speed capture capability of a CCD-based system like the SPIC-301 can be advantageous. However, the LISUN LMS-6000, when used with a high-speed photometric head and its associated flicker analysis software, provides highly accurate measurements of flicker percentage, flicker index, and waveform, compliant with standards like IEEE PAR1789.
