These sensors have a thin metallic or black absorption layer leading to a faster heat transfer to the sensor element. Repetition rates up to more than 2000 pps. are possible. The spectral behaviour is flat in the VIS and NIR but for longer wavelengths the absorption properties have to be taken into account. Main application is the use at one wavelength. The metallic coating of the two UV types is more stable in the ultraviolet region than the organic black coating.