The PMO8 radiometer is a reference instrument to measure direct solar irradiance. It is available since 2020, it has been developed as the successor of the PMO6 radiometer from PMOD/WRC, that is widely used as a calibration reference for solar sensors. As well as the PMO6, the PMO8 is an absolute pyrheliometer and fulfils the requirements of a primary standard according to the WMO CIMO-Guide.
The PMO8 system consists of the sensor unit Fliana and the control unit Linard.
Principle of operation
The PMO8 is an electrical substitution radiometer, it means the principle of measurement is based on the substitution of solar radiant power with electrical power. The sensor unit Fliana features two light absorbing detectors: A reference detector (in the dark) that is heated with constant electrical power and an active detector that is electrically heated, so that the heat flux from both detectors to the common heat sink is equal. If the active detector is exposed to solar radiation, the electrical power needed to keep the thermal equilibrium is reduced by the amount of the radiant power. Thus the radiant power can easily be measured as a difference in electrical power. The design with two detectors makes the setup very robust against environmental influences.
The control unit Linard handles the measurement task (cavity balancing circuit, shutter control) and acquires the detector’s power signal. The control unit Linard features a web-server and is easily accessible through a web-browser application.
Traceability
The PMO8 system is calibrated against the World Radiometric Reference (WRR) at PMOD/WRC in Davos Switzerland.
Availability, Quotes and Specifications
The PMO8 Basic system is manufactured in small series, lead times can vary. For detailed specifications, quotes and lead times, please contact us at or request a quote here.
Frequently Asked Questions
More details can be found in the PMO8 FAQ.
