A new entrance optic for a Brewer spectrophotometer has been designed and tested both in the laboratory and during solar measurements. The integrated cosine response deviates by 2.4% from the ideal, with an uncertainty of ±1%. The systematic uncertainties of global solar irradiance measurements with this new entrance optic are considerably reduced compared with measurements with the traditional design. Simultaneous solar irradiance measurements between the Brewer spectrophotometer and a spectroradiometer equipped with a state-of-the-art shaped diffuser agreed to within ±2% during a five-day measurement period.
© 2003 Optical Society of America
(010.1290) Atmospheric and oceanic optics : Atmospheric optics
(120.5630) Instrumentation, measurement, and metrology : Radiometry
(120.6200) Instrumentation, measurement, and metrology : Spectrometers and spectroscopic instrumentation
(260.7190) Physical optics : Ultraviolet
Julian Gröbner, "Improved Entrance Optic for Global Irradiance Measurements with a Brewer Spectrophotometer," Appl. Opt. 42, 3516-3521 (2003)