Design and implementation of ultra-wide dynamic range low-light-level calibrator

To address the demands of low-light-level(LLL) meter verification, laboratory measurements, micro-light compensation, starry sky simulation, and various tests and detections under low-illumination conditions, a verification device for LLL meter with ultra-wide dynamic range was developed. This device is a high-precision micro-light system featuring compact overall structure, integrating an optical platform, an electronic compartment, a wide-illuminance uniform light source module, and a sample compartment. The cascaded integrating sphere light source and secondary adjustable diaphragm were designed through theoretical calculations, ensuring the color temperature of illuminance detection surface stabilized at 2856 K. The device comprised subsystems including a power supply system, an electric diaphragm system, and a micro-light detection system, all of which could meet the technical specifications of the wide-illuminance uniform light source integrating sphere system. By optimizing key technologies such as dimming algorithm calibration and calibration measurement, the micro-illuminance value could be adjusted over 7 orders of magnitude. Performance retesting experiments were carried out using standard first-class weak-light illuminance meter. The results indicate that the LLL dynamic range of the device spans from 1×10⁻⁷ lx to 1×10⁰ lx, and the measurement accuracy of the integrating sphere LLL source within the dynamic range of the standard first-class LLL meter is better than 1%.