SEI SR-2500 Portable Field Spectroradiometer
| Brand | SEI |
|---|---|
| Origin | USA |
| Model | SR-2500 |
| Spectral Range | 350–2500 nm |
| Spectral Resolution | 3.5 nm (350–1000 nm), 7 nm / 10 nm (configurable), 22 nm @ 1500 nm & 2100 nm |
| Spatial Resolution (IFOV) | Optional (4°, 8°, 14° lenses |
| Field of View (TFOV) | Optional |
| Imaging Resolution | 1280 × 1024 |
| Frame Rate | 30 fps |
| Detector | 512-pixel Si array (350–1000 nm), 256-pixel cooled InGaAs array (970–2500 nm) |
| Noise-Equivalent Radiance (1.2 m fiber) | 0.8×10⁻⁹ W/cm²/nm/sr @ 400 nm |
| Integration Time | 7.5–1000 ms |
| Wavelength Repeatability | ±0.1 nm |
| Wavelength Accuracy | ±0.5 nm |
| Interface | USB 2.0 + Bluetooth 4.0 |
| Dimensions | 21.6 × 29.2 × 8.9 cm |
| Weight | 3.3 kg (7.3 lbs) |
| Battery | Rechargeable Li-ion, 7.4 V, >2 h continuous operation (up to 4 h typical field use) |
Overview
The SEI SR-2500 Portable Field Spectroradiometer is a high-performance, filter-based hyperspectral measurement system engineered for precision ground-based spectral characterization across environmental, agricultural, geological, and industrial applications. Unlike scanning or push-broom instruments, the SR-2500 employs a dual-detector architecture—comprising a 512-element silicon photodiode array (350–1000 nm) and a thermoelectrically cooled 256-element InGaAs array (970–2500 nm)—to deliver simultaneous, non-scanning acquisition across the full UV-VIS-NIR-SWIR spectrum (350–2500 nm). Its fixed-grating, all-reflective optical path eliminates moving parts, ensuring mechanical stability and long-term radiometric consistency under variable thermal and vibration conditions typical of field deployment. The instrument operates on the principle of discrete-band spectral sampling using precision interference filters and holographic diffraction gratings, enabling high signal-to-noise ratio (SNR) measurements without spectral aliasing or mechanical drift. Designed for compliance with ASTM E275, ISO 9001 calibration traceability protocols, and NIST-traceable reference standards, the SR-2500 supports quantitative reflectance, transmittance, and radiance measurements essential for validation of remote sensing products and in situ spectral library development.
Key Features
- Full-spectrum coverage from 350 nm to 2500 nm with dual-array detector architecture and thermoelectric cooling for InGaAs channel stability
- No moving optical components: robust all-reflective design with holographic grating ensures high reproducibility and minimal maintenance
- Integrated shutter and drift-lock auto-calibration system for real-time dark-current compensation and wavelength stabilization
- Modular optical interface: interchangeable fore-optics—including 4°, 8°, and 14° field-of-view lenses, 25° fiber optic probe, and integrating sphere—enabling flexible sample geometry adaptation
- Bluetooth 4.0 and USB 2.0 connectivity for seamless integration with Windows-based PCs, ruggedized PDAs (e.g., Getac PS336), or tablet platforms
- Lightweight aluminum chassis with ergonomic nylon handle and thermal mass optimization for stable performance across –10 °C to +45 °C ambient conditions
- Rechargeable lithium-ion battery pack (7.4 V) supporting ≥4 hours of continuous field operation per charge
Sample Compatibility & Compliance
The SR-2500 accommodates diverse sample types through its configurable optical interface: flat or irregular natural surfaces (soil, vegetation canopies, rock outcrops), liquid suspensions (via fiber-coupled cuvette holders), manufactured materials (paints, coatings, solar absorbers), and atmospheric downwelling irradiance (using cosine corrector). It meets functional requirements for GLP-compliant spectral data acquisition when operated with audit-trail-enabled software configurations. Measurement protocols align with ISO 17025 laboratory accreditation criteria for spectral radiometry, and raw data output conforms to HDF5 and ENVI-compatible BIL formats for interoperability with ENVI, QGIS, and NASA’s ASFDA tools. Optional GPS-embedded PDA integration enables geotagged spectral logging compliant with USGS Spectral Library metadata standards (Version 7.0).
Software & Data Management
Bundled DARWin CE Mobile-compatible software provides real-time spectral preview, automated dark/light reference capture, and on-device calculation of 12+ vegetation indices—including NDVI, EVI, SAVI, PRI, WBI, and GRVI—directly aligned with Landsat, Sentinel-2, MODIS, and AVHRR bandpass definitions. The software includes built-in USGS mineral spectral library (v. 2023) for automated spectral matching via spectral angle mapper (SAM) and Euclidean distance algorithms. All measurement sessions record full metadata (GPS coordinates, UTC timestamp, integration time, FOV, battery voltage, ambient temperature) in XML sidecar files. Export options include CSV, ASCII, and radiance-corrected reflectance spectra normalized to NIST-traceable standards. For regulated environments, optional FDA 21 CFR Part 11-compliant software modules provide electronic signatures, user access controls, and immutable audit trails.
Applications
- Field validation of satellite and airborne hyperspectral sensors (e.g., PRISMA, EnMAP, AVIRIS-NG)
- Quantitative crop health assessment and precision agriculture decision support
- Mineral identification and lithological mapping in exploration geochemistry
- Forestry biomass estimation and species classification using spectral unmixing
- Marine and freshwater optically complex water column characterization
- Industrial lighting quality analysis (CIE color space metrics, CCT, CRI)
- Solar energy material evaluation (spectral responsivity, quantum efficiency)
- Atmospheric aerosol optical depth (AOD) and water vapor column retrieval via sun photometry mode
FAQ
What spectral calibration standards are supported?
The SR-2500 is factory-calibrated against NIST-traceable tungsten-halogen and deuterium lamps, with optional annual recalibration services available through SEI’s ISO/IEC 17025-accredited metrology lab.
Can the SR-2500 operate in fully autonomous mode without external computing?
No—the SR-2500 requires an external host device (PC, PDA, or tablet) for control and data storage; it does not feature onboard memory or display, by design, to maximize battery life and thermal stability.
Is the instrument suitable for UAV-mounted deployment?
While designed primarily for handheld and tripod-based terrestrial use, the SR-2500 has been successfully integrated into stabilized gimbal systems for low-altitude UAV surveys, subject to payload weight and power interface compatibility verification.
How is radiometric accuracy maintained during extended field campaigns?
Through periodic dark-current acquisition, internal shutter-based zero-radiance referencing, and optional use of calibrated reference panels (e.g., Spectralon® 99% reflectance) before and after each measurement sequence.
Does the software support batch processing of large spectral datasets?
Yes—DARWin CE includes command-line scripting and Python API extensions for automated preprocessing, index computation, and spectral library generation across multi-site campaign datasets.
