Cosine correction diffusers

Radiometers consists of filters, a sensor (silicon radiation detectors, which are sensitive in the range 200-1100 nm, or vacuum photodiodes with specific photocathode materials) and an input optical attachment such a cosine correction diffuser or fibre optic assembly [1762, 1770]. The current of the sensor is converted to a voltage by the converter module . This output voltage (0-5 V) can monitor the relative intensity of emitted radiation of 0-100%. This value can simply be displayed using an analogue or digital instrument, calibrated in any radiometric and/or photometric units. 

The cosine correction diffuser provides the detector with a cosine spatial response, which means it will see irradiance in the same manner as the flat surface of the substrate when it is exposed to UV curing irradiation. 

In (3) ftg is the direct to global irradiance ratio, fd is the diffuse cosine correction factor and fb the direct cosihe correction factor, which is determined in the laboratory. A full description of the cosine correction procedure along with the uncertainties involved are described in detail in Bais et al., (1998). 

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