About the possibility of calibrating optical detectors by solar radiation

Abstract

Whereas information on absolute detected/emitted irradiation is not required for determination of absorbance or transmittance, this information is essential to quantitatively analyse nearly any photo-induced reaction. Some examples/applications are photo catalysis, photo degradation, optical materials, photo synthesis, photochemical kinetics and dynamics of solar energy – that is, all procedures for studying the influence of a large number of photons. The only way to control the irradiation is to have access to an optical radiometer with known and defined parameters. Due to aspects such as receiver quantum yield and construction influences, absolute and spectral calibrations must be considered. Fibre-couplet optical detectors based on the CCD technique are affordable and variability is a major advantage. But for spectral calibration no comparable procedure exists. Additionally, constructed stable reference light sources with known and suitable radiance (>200 W m⁻²), with sufficient illumination area and exactly known broadband wavelength distribution are not easily accessible or do not exist. A novel procedure is presented here using natural solar radiation for calibration of intensity and energy.