The ANCAL type COS7 Cosine Receptor provides for the reception of optical radiation. The measure of the optical radiation approximates that striking a flat surface. Hence, the Cosine Receptor provides measurements of flux densities as a plane surface would receive radiation from all angles of a hemisphere.

Such measurements are of the flux density per unit area. Because the collector material is of PTFE, there is minimum diffuse reflectance The shape of the collector results in better cosine response as compared with that of a flat surface, which will tend to lose radiation.

The COS7 Cosine Receptor can be used with most any fiber optic input spectrometer which has either an SMA connector or a 0.375 inch diameter metal tip. The COS7 is robust and will perform reliably in the field .

A specially enhanced Cosine Receptor for ultra violet radiation is also available. The collector is of Spectralon®, which has a relatively high transmittance for UV-A, -B, and -C.

Because the COS7 is a passive receptor of optical radiation, each COS7 needs to be calibrated as part of the specific spectrometer system with which it is used. When calibrated, it can provide accurate irradiance measurements with most fiber optic spectrometers.