Besides standard detector responsivity calibration services, Gigahertz-Optik offers a field-of-view calibration service for light detectors. The FOV calibration is offered for all irradiance and illuminance detectors employing diffuser windows for a cosine corrected measurement geometry. The calibration is done with a light source at a distance from the detector. The test detector is mounted onto a goniometric rotary table. It’s diffuser surface is aligned to the axis of the rotary table. The signal as a function of the viewing angle is measured and compared with the ideal cosine spatial function. The measured characteristic as well as the calculated f2 uncertainty is stated in the factory calibration certificate.