![licor par](https://test148838771.files.wordpress.com/2018/10/licor-par.jpeg?w=720)
The PAR quantum sensors measure PAR in units of photosynthetic photon flux density (PPFD). They are photovoltaic sensors with hemispherical field of view achieved by a diffuser. Filters are used to allow radiation between 400 to 700nm to pass through. Several commercial PAR sensors are available such as: LI-190R Quantum Sensor, MQ-303, Quantum sensors by apogee instruments.