Detector‐Based Calibration Method for High‐Accuracy Solar UV Measurements

A novel method for calibrating the absolute responsivity of solar UV spectroradiometers has been developed and tested. The method is based on calibrated filter radiometers constructed from a detector, a precision aperture, a band‐pass filter and devices for temperature stabilization. The filter radiometers utilize a trap detector with very low reflectance. The filter and the detector can therefore be characterized separately. As an example the detector‐based calibration is compared at 312 nm wavelength with lamp‐based calibration by measuring the irradiance of a deuterium lamp with both the filter radiometer and the lamp‐calibrated spectroradiometer. The agreement between the results is at the level of 1%, well within the estimated uncertainties of both methods.