|  |

| |

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

Apogee Extended Range PFD SQ620 Series

Measure photon flux density (PFD) from 340-1040 nm

Apogee’s new extended range photon flux density (PFD) sensors are for measuring the newest generation of LED grow lights with wavelengths outside the traditional 400-700 nm PAR range. Research has shown the value of adding UV and far-red LEDs to achieve various disease control and photomorphogenic effects. The extended range filter of the SQ-620 allows it to measure photons from UV and Far-red. The 1040 nm top cutoff also means the sensor will measure the thermal output of HPS fixtures and other broad-spectrum lights above the range that influences plants; therefore, the sensor is intended only for use in LED environments.

The SQ620 Series sensors feature a rugged, aluminum housing that is fully-submersible and built to withstand harsh conditions. The sensor cable includes an IP68 marine-grade stainless-steel cable connector to simplify sensor removal and replacement from permanent installations for maintenance and calibration. Typical applications of Extended Range PFD sensors include incoming PFD measurements over plant canopies in indoor greenhouses or in growth chambers, and reflected or under-canopy (transmitted) PFD measurements in the same environments. Since the detector on this particular Extended Range sensor is sensitive to radiation with wavelengths up to 1100 nm, beyond the range of wavelengths that influence plants, we recommend only using the SQ-620 series sensors in indoor grow environments utilizing LED lights.

 

  • The SQ-624 Extended Range PFD is an amplified sensor with a 4 to 20 mA output.
  • The SQ-620 Extended Range PFD sensor is a self-powered sensor.
  • The SQ-627 Extended Range PFD is a digital sensor with SDI-12 communication protocol.

 

Extended Range PFD Sensor

Radiation that drives photosynthesis is called photosynthetically active radiation (PAR) and is typically defined as total radiation across a range of 400 to 700 nm. PAR is almost universally quantified as photosynthetic photon flux density (PPFD) in units of micromoles per square meter per second (µmol m-2 s-1, equal to microEinsteins per square meter per second) summed from 400 to 700 nm (total number of photons from 400 to 700 nm). However, ultraviolet and far red photons outside the defined PAR range of 400-700 nm can also contribute to photosynthesis and influence plant responses (e.g., flowering).

Sensors that measure PPFD are often called quantum sensors due to the quantized nature of radiation. A quantum refers to the minimum quantity of radiation, one photon, involved in physical interactions (e.g., absorption by photosynthetic pigments). In other words, one photon is a single quantum of radiation. Sensors that function like traditional quantum sensors, but measure a wider range of wavelengths can be thought of as an ‘extended range’ quantum sensor.

Typical applications of traditional quantum sensors include incoming PPFD measurement over plant canopies in outdoor environments or in greenhouses and growth chambers, and reflected or under-canopy (transmitted) PPFD measurement in the same environments. The Extended Range Quantum Sensor uses a detector that is sensitive to radiation up to about 1100 nm, well beyond the range of wavelengths that influence photosynthesis and plant responses. This means this particular sensor should only be used for photon flux density measurements under LEDs.

 

Where are the SQ-620 Series used?

The SQ-620 Series sensors are used for measuring the newest generation of LED grow lights with wavelengths outside the traditional 400-700 nm PAR range. Research has shown the value of adding UV and far-red LEDs to fixtures to achieve various disease control and photomorphogenic effects. The extended range filter of the SQ-620 allows it to measure photons from UV and Far-red. The 1040 nm top cutoff also means the sensor will measure spikes in HID and other broad spectrum lights above the range that influences plants therefore the sensor is only intended for use in LED grow environments.

Available Package

Packages that pair a SQ-620 sensor with a micro logger include the PQ-620.

SQ-620 SQ-624 SQ-627
Power Supply Self-powered 12 to 24 V DC 5.5 to 24 V DC
Current Draw Maximum of 20 mA 1.4 mA (quiescent), 1.8 mA (active)
Sensitivity 0.05 mV per µmol m-2 s-1 0.004 mA per µmol m-2 s-1
Calibration Factor 20 µmol m-2 s-1 per mV 250 µmol m-2 s-1 per mA
Calibration Uncertainty ± 5 % ± 5 % ± 5 %
Measurement Range 0 to 4000 µmol m-2 s-1 0 to 4000 µmol m-2 s-1 0 to 4000 µmol m-2 s-1
Measurement Repeatability Less than 0.5 % Less than 0.5 % Less than 0.5 %
Calibrated Output Range 0 to 200 mV 4 to 20 mA 0 to 200 mV
Long-term Drift per Year Less than 2 % per year Less than 2 % per year Less than 2 % per year
Non-linearity Less than 1 % (up to 4000 µmol m-2 s-1) Less than 1 % (up to 4000 µmol m-2 s-1) Less than 1 % (up to 4000 µmol m-2 s-1)
Response Time Less than 1 ms Less than 1 ms Less than 0.6 s
Field of View 180° 180° 180°
Spectral Range 340 to 1040 nm ± 5 nm (wavelengths where response is greater than 50 % of maximum) 340 to 1040 nm ± 5 nm (wavelengths where response is greater than 50 % of maximum) 340 to 1040 nm ± 5 nm (wavelengths where response is greater than 50 % of maximum)
Directional (Cosine) Response ± 2 % at 45°; ± 5 % at 75° zenith angle ± 2 % at 45°; ± 5 % at 75° zenith angle ± 2 % at 45°; ± 5 % at 75° zenith angle
Azimuth Error Less than 0.5 % Less than 0.5 % Less than 0.5 %
Tilt Error Less than 0.5 % Less than 0.5 % Less than 0.5 %
Temperature Response -0.11 ± 0.04 % per C -0.11 ± 0.04 % per C -0.11 ± 0.04 % per C
Uncertainty in Daily Total Less than 5 % Less than 5 % Less than 5 %
Housing Anodized aluminum body with acrylic diffuser Anodized aluminum body with acrylic diffuser Anodized aluminum body with acrylic diffuser
IP Rating IP68 IP68 IP68
Operating Environment -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m
Dimensions 30.5 mm diameter, 37 mm height 30.5 mm diameter, 37 mm height 30.5 mm diameter, 37 mm height
Mass (with 5 m of cable) 140 g 140 g 140 g
Cable 5 m of two conductor, shielded, twisted-pair wire; TPR jacket; pigtail lead wires; stainless steel (316), M8 connector located 25 cm from sensor head 5 m of two conductor, shielded, twisted-pair wire; TPR jacket; pigtail lead wires; stainless steel (316), M8 connector 5 m of two conductor, shielded, twisted-pair wire; TPR jacket; pigtail lead wires; stainless steel (316), M8 connector
Warranty 4 years against defects in materials and workmanship 4 years against defects in materials and workmanship 4 years against defects in materials and workmanship