MQS-B

The Cosine Corrected Mini Quantum Sensor MQS-B is designed for light measurements in units relevant for plant leaves.

For photosynthesis research, sensors with spectral and directional sensitivity relevant for plants are required.

A cosine corrected sensor measures incident PAR radiation on a flat surface. In this way, it enables the most accurate measurement of photosynthetically active radiation, considering the angle of incidence.

The MQS-B sensor detects photosynthetically active radiation (PAR), which is the electromagnetic radiation between 400 and 700 nm.

More specifically, it measures the photosynthetic photon flux density (PPFD), which is the amount of PAR hitting a surface from one side, whereby beams not perpendicular to the surface only contribute with the cosine of their angle of incidence measured to the surface-normal. The unit for PPFD is μmol m-2 s-1.

Fig. 1 shows the typical response between 350 nm and 750 nm of a MQS-B sensor. The solid line shows the ideal response of a photon flux sensor for photosynthetically active radiation. For comparison Fig. 2, shows the response to energy fluence rate from 350 – 750 nm.

The MQS-B sensor uses a plastic diffuser to obtain an angular response error of less than ± 4% (-80…80 ° angle). Fig. 3 shows a typical angular response curve of the MQS-B sensor compared to the ideal characteristic.