Radiometers are used to measure the intensity of electromagnetic radiation (e.g., UVC, UVB, UVA, Vis, and IR). They are univariate devices that do no distinguish between light of different wavelengths. In addition to wavelength range, radiometers carry specifications such as sensor diameter, power range, accuracy, resolution, operating temperature range, and humidity range.  The wavelength range specifies the detection range for radiometers. The sensor diameter measures the active part of the sensor. Power range is the power per unit area. Radiometer accuracy is usually given as a percentage. The resolution of the detector is a measure of radiometer sensitivity. Operating temperature and humidity range are also important specifications to consider when selecting radiometers.