Reference Radiometer for Irradiance Meters Calibration: A Characterization Comparison Between Two Methods

The continuous need to calibrate radiometers makes us think and consider which of the utilized calibration methods provides the desired purpose with a high accuracy, high degree of stability in repeatability and reproducibility, and less estimated uncertainty value as possible. This study compares two common standard calibration methods that emerged and applied to two radiometers held in the radiometry lab at the National Institute of Standards (NIS), Giza, Egypt. The results concluded that the ND-filters method of calibration achieves the purpose of the study, exhibits more stability (STDEV 4% and 7%) and less combined uncertainty 2.7% and 9.4% for the two radiometers under test.