MQS-B Mini Quantum Sensor

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Product

Cosine Corrected Mini Quantum Sensor

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.

General Features MQS-B Mini Quantum Sensor

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.

Spectral Response

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.

Fig. 1: Typical spectral response of the MQS-B sensor for photon flux density (PFD), blue line with dots; pink line: ideal response for PAR sensors.

Angular Response

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.

Fig. 3: Angular response. Black dots: Typical angular response of the MQS-B sensor; green line: Ideal cosine response.

MQS-B Mini Quantum Sensor

Design of sensor

Mini quantum sensor for selective PAR (photosynthetically active radiation) measurement, cosine corrected for PPFD (photosynthetical photon flux density) measurement.

Sensor housing

Black anodized aluminum housing

Diffuser material

Perspex

Signal detection

High stability silicone photovoltaic detector with filter set for PAR correction (to learn more about the typical sensitivity see “General Features”). Signal output typically -2 μA / (1000 μmol m-2 s-1)

Temperature coefficient of photodiode

0.01 %/K

Absolute calibration

± 5 %

Angular dependence

error < 4 % between angles from -80° to +80° from normal axis

Immersion coefficient

Typically 1.32

Operating temperature

- 5 °C … + 45 °C

Cable length

3 m

Connector

BNC

Power supply

Not required

Size

Height: 16 mm
Diameter: 14 mm
Diffuser diameter: 5.5 mm

Weight

32 g

Design
Cosine-response mini quantum sensor for selective measurement of photosynthetically active radiation (PAR, 400 – 700 nm) with Perspex diffuser disk as light entrance and signal amplifier box
Signal detection
High stability silicone photovoltaic detector with filter set providing equal response to photon fluxes across the PAR spectral range. The typical signal output of the detector is 2 μA / (1000 μmol m‑2 s‑1)
Temperature coefficient of photodiode
0.01 %/K
Absolute calibration
± 5 %
Angular dependence
error < 4 % between angles from -80° to +80° from normal axis
Immersion coefficient
Typically 1.32
Cable length
3 m
Size: Height
16 mm; diameter: 14 mm; Diffuser diameter: 5.5 mm
Weight
32 g
Amplifier box
Two amplification ranges (0 to 1000 and 0 to 20,000 μmol m‑2 s‑1, each range corresponding to 0 to 2.5 V DC). To be connected to the Leaf Clip Holder 2030-B port of the PAM-CONTROL unit. Power provided by the PAM-CONTOL unit. Dimensions: 5 cm x 3 cm x 5 (W x H x D). Weight: 200 g.
Design

Plastic cover with crease protection

Dimensions

23 x 32 cm

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.