US-SQS/L

Especially under water or when working with suspensions, the amount of scattered light is very high, so that a spherical sensor should be used. The US-SQS sensor uses a plastic diffuser to obtain an angular response error of less than ± 5% from -100° to 100° angle.

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

The US-SQS/L measures photosynthetically active radiation (PAR), which is the electromagnetic radiation between 400 and 700 nm.

More specifically, it measures the photosynthetic photon fluence rate (PPFR), which is the amount of PAR hitting a point or small sphere from all directions weighted equally divided by the cross-sectional area of the sphere and time-interval. The unit for PPFR is μmol m-2 s-1.

The US-SQS sensor uses a plastic diffuser to obtain an angular response error of less than ± 5% (-100…100° angle). Fig. 3 shows a typical angular response curve.

Fig. 1 shows the typical response between 350 nm and 750 nm of a US-SQS sensor. The solid line shows the ideal response of a photon fluence sensor for photosynthetically active radiation (PAR, defined for the 400 – 700 nm wavelength range. For comparison Fig. 2, shows the response to energy fluence rate from 350 – 750 nm.