The pyranometer LP PYRA 10 is based on a thermopile sensor which surface is covered by a matt black paint so to allow the instrument not to be selective at various wavelengths. The spectral range of the pyranometer is determined by the transmission of the two glass domes type K5. The new sensor allows a response time less than the requirements of the ISO9060 standard for classifying Secondary pyranometers (response time is generally less than 9 seconds, where ISO9060 standard requires a response time less than 15 seconds).
Radiant energy is absorbed/radiated from the surface of the blackened thermopile, creating a temperature difference between the centre of the thermopile (hot junction) and the body of pyranometer (cold junction). The temperature difference between hot and cold junction is converted into Potential Difference thanks to the Seebeck effect.
A second thermopile is mounted inside the instrument and not accessible by light.
This second thermopile, connected anti-series with respect to the sensor exposed to light, reduces the signals of pyranometer in sudden temperature changes (thermal shock).