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Enabling better global research outcomes in soil, plant & environmental monitoring.

US-SQS/L Submersible Spherical Micro Quantum Sensor

When taking measurements under water or when working with suspensions, the amount of scattered light is very high. To compensate for this, 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.

US-SQS Sensor

Design of sensor: 3.7 mm diameter white plastic diffusing sphere connected via internal 2 mm plastic light guide with detector
Sensor housing: Stainless steel
Signal detection: High stability silicon photovoltaic detector (blue enhanced) with filter set for PAR correction (380 to 710 nm)
Signal output in air: Typically 3.5 μA / 1000 μmol m-2 s-1
Response time of photodiode: Rise and fall time of photocurrent (RL = 50 Ω; VR = 5 V; λ = 850 nm; IP = 800 μA): 25 ns
Temperature coefficient of photodiode: 0.18 %/K
Absolute calibration: In air, with correction for the spectral difference between the calibration lamp and sun light: ± 5%
Immersion coefficient: 1.72 ± 2%
Angular response: < 5% error up to 100° from normal axis
Azimuth: < 5% error over 360° at 90° from normal axis
Power supply: Not required
Operating temperature: – 5°C to + 45°C
Submersible: Down to 2.8 m below water surface (only sensor and cable – not the connector)

US-SQS/L

Application: Measurement of photosynthetic photon fluence rate in air or water
Connects to: ULM-500
Connector: BNC
Signal output: Typically -3.5 μA / (1000 μmol m-2 s-1) in air
Cable length: 3 m
Dimensions: Diameter 1 cm, length: 11 cm
Weight: 62 g

US-SQS/IB

Application: Suspension cuvette of PAM-100 and XE-PAM (additional amplifier required for direct connection). Includes hood for suspension cuvette
Connects to: ULM-500
Connector: BNC
Signal output: Typically -3.5 μA / (1000 μmol m-2 s-1) in air
Cable length: 3 m
Dimensions: Sensor: Diameter 1 cm, length: 11 cm; Hood: Diameter 3.4 cm, height: 3.2 cm
Weight: 85 g

US-SQS/WB

Application: Suspension cuvette
Connects to: WATER-PAM, PAM-100 (PDA-100), XE-PAM (PDA-100), DUAL-PAM-100, ULM-500 (AUX), PAM-2500 and MINI-PAM (instead of Leaf Clip Holder 2030-B or 2060 M)
Connector: Same as Leaf Clip Holder 2030-B. Includes hood for suspension cuvette, amplifier for aux input of PAM Control
Signal output: 0 to 2.5 V DC / 0 to 1000 μmol m-2 s-1 or 0 to 2.5 V DC / 0 to 20,000 μmol m-2 s-1
Power: Provided by connected instrument
Cable length: 3 m + 0.5 m
Dimensions: Sensor: Diameter 1 cm, length: 11 cm; Hood: Diameter 3.4 cm height: 3.2 cm; Amplifier: 5 x 5 x 5 cm (W x L x H)
Weight: 175 g

US-SQS/B

Application: Suspension cuvette
Connects to: PHYTO-PAM
Connector: Includes hood for suspension cuvette, amplifier for aux input of Phyto-PAM control unit
Signal output: 0 to 2.3 V DC / 0 to 172.5 μmol m-2 s-1 or 0 to 2.3 V DC / 0 to 3450 μmol m-2 s-1, automatic adjustment
Power: 9V Block battery
Cable length: 3 m + 1.5 m
Dimensions: Sensor: Diameter 1 cm, length: 11 cm; Hood: Diameter 3.4 cm, height: 3.2 cm; Amplifier: 10.5 x 5.5 x 4.5 cm (W x L x H)
Weight: 450 g

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.

Spectral Response

US-SQS Figure 1

Fig. 1 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.

 

US-SQS Figure 2

For comparison Fig. 2, shows the response to energy fluence rate from 350 – 750 nm.

Angular Response

US-SQS Figure 3

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