US-SQS/L Spherical Micro Quantum Sensor

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Product

Submersible Spherical Micro Quantum Sensor

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.

General Features US-SQS/L

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.

Fig. 1: Spectral sensitivity of US-SQS sensor; blue line with dots: Typical spectral sensitivity for photon fluence rate (PFR); pink line: Ideal response for PAR sensors.

Spectral Response

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.

Angular Response

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.

US-SQS/L Spherical Micro Quantum 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 … + 45 °C
Submersible
Down to 2.8 m below water surface (only sensor and its cable – not the connector)
Application

Measurement of photosynthetic photon fluence rate in air or water

Connects to

E.g. ULM-500

Connector

BNC

Signal output

Typically -3.5 μA / (1000 μmol m-2 s-1) in air

Cable length
3 m
Size

Diameter: 1 cm

Length: 11 cm

Weight

62 g

Application

Suspension cuvette

Connects to

E.g. ULM-500

Connector

BNC, includes hood for suspension cuvette

Signal output

Typically -3.5 μA / (1000 μmol m-2 s-1) in air

Cable length

3 m

Size

Sensor: Diameter 1 cm
Length: 11 cm
Hood: Diameter 3.4 cm
Height: 3.2 cm

Weight

85 g

Application

Suspension cuvette

Connects to

WATER-PAM, 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…2.5 V DC / 0…1000 μmol m-2 s-1 or 0…2.5 V DC / 0…20.000 μmol m-2 s-1 Power
Provided by connected instrument

Cable length
3 m + 0.5 m
Size

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

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...2.3 V DC / 0...172.5 μmol m-2 s-1 or 0...2.3 V DC / 0...3450 μmol m-2 s-1, automatic adjustment

Power

9-V-Block battery

Cable length

3 m + 1.5 m

Size

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

Design

Plastic cover with crease protection

Dimensions

23 x 32 cm

Accessories

Design

Light grey plastic housing with connectors, membrane keyboard and a white illuminated LCD graphic display

Dimensions

12 x 7.5 x 3.5 cm

Weight

210 g (including 4 AAA 1.5 V batteries)

Power supply

4 AAA-type batteries or 5 V DC from USB voltage source when connected to the computer

Working conditions

up to 85 % rH (avoid condensation), - 20° to + 50°C ambient temperature

Time resolution

PAR channel #1: 100 samples / second, PAR channel #2 and other channels: 5 samples / second (connected to computer running WinControl-3 software)

Operation time

10 days or ca. 100 days automated logging with sleep mode (1 meas. / 5 min). Unlimited working time via USB connection (PC-software WinControl-3 – no sleep mode)

Inputs
  • Two BNC-connectors for the connection of two PAR-sensors with individual calibration factors between -50.0 and -9999.9 (memory for 10 calibration factors), range switchable in 5 steps 250 nA to 0.6 mA
  • Connector for Monitoring Leaf-Clip JUNIOR-B; an adapter is available for the connection of the Leaf-Clip Holder 2030-B, and the Micro Quantum/Temp.-Sensor 2060-M
  • Connector for additional digital sensors (still under development)
  • USB-Connector for connection with computer (software: WinControl-3)
Memory

Flash memory used as ring buffer for 50000 lines (1 line / single measurement)

Display

White illuminated graphic display with 5 different display modes (1: all data; 2-4: two selected sensors in big letters; 5: chart mode for channel no. 1, with maximum, minimum and average indicated), resolution: 0.1 μmol m-2 s-1

Computer Connection

1 free USB socket. Processor, 1 GHz. RAM, 256 MB. Hard disc space, 20 MB. Screen resolution: 800 x 600 pixels. Interface, USB 1.1, 2.0 and 3.0. Operating system: Microsoft Windows 10 and 11.