Development of a compact and portable signal-to-noise ratio measurement system for low-light imaging sensors

Accurate signal-to-noise ratio (SNR) characterization is imperative for the development of optimized sensors for low-light imaging applications in environmental monitoring, infrastructural assessment, and disaster preparedness for nocturnal remote sensing. Lab-based conventional approaches are held back by mobility issues, limited dynamic range, and thermomechanical instability, which translate into restricted applications for the fields. This work introduces a portable, high-precision SNR measurement device that combines a dual-integrating sphere light source capable of outputting from 10^-6 to 10³ lx with a thermoelectric-cooled silicon photodiode. Real-time feedback control provides 0.04% intensity stability, while digital filtering with a 10 Hz bandwidth results in a relative measurement uncertainty of 2.7% for the 10^-4 to 10^-2 lx range. Field validation proved a 98.3% correlation with lab standards, establishing reliability for in-situ calibration. It provides ±0.5°C thermal stability from -40°C to +70°C and possesses 1.8% measurement repeatability. This development presents a standard methodology for the calibration of field-based low-illumination sensors, empowering data integrity for lunar-illumination-based vegetation monitoring as well as metropolitan light pollution research.