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

Apogee Full Spectrum Quantum PAR SQ-500 Series

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 often expressed as photosynthetic photon flux density (PPFD): photon flux 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). While Einsteins and micromoles are equal (one Einstein = one mole of photons), the Einstein is not an SI unit, so expressing PPFD as µmol m-2 s-1 is preferred.

Sensors that measure PPFD are often called quantum sensors due to the quantized nature of radiation. A quantum referes 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. Apogee Instruments SQ series quantum sensors consist of a cast acrylic diffuser (filter), photodiode, and signal processing circuitry mounted in an anodized aluminum housing, and a cable to connect the sensor to a measurement device. Sensors are potted solid with no internal air space. The range of SQ-500 series quantum sensors are designed for continuous PPFD measurement in indoor and outdoor environments:

See the SNiP in the Dynamic Catalogue

 

 


SQ-500 Quantum Sensor

The SQ-500 is a self-powered, analog full-spectrum quantum sensor with a 0 to 40 mV output. The SQ-500 is also available as a package with a microCache Bluetooth micro-logger at a special introductory price (with cable lengths of 30cm and 2M available).

 

SQ-512: Amplified 0-2.5 V Full-Spectrum Quantum Sensor

The SQ-512 is an amplified full-spectrum quantum sensor with a 0 to 2.5 V output. The SQ-500 is a full spectrum quantum sensor with a spectral range of 389 to 692 nm ± 5 nm, which can be seen in the graph below. This improved spectral response increases the accuracy of LED measurements. The SQ-500 is used to measure incoming PPFD measurements in outdoor environments, greenhouses, growth chambers, and aquariums. Back to Top

 

SQ-520: Smart Quantum Sensor

The new SQ-520 smart quantum sensor can be connected directly to a computer for taking spot measurements or graphing and datalogging real-time PPFD using the included software. The sensor can also act as a stand-alone PAR datalogger by simply connecting it to any standard 5V DC USB power plug. Internal memory within the sensor head is capable of storing 10,000 user-specified periodic measurements that can be downloaded as a CSV file to a computer for analysis. The SQ-520 is used to measure incoming and reflected PPFD around plants and other organisms in outdoor environments, greenhouses, growth chambers, and underwater.

  • No Datalogger Required.
  • Internal Data Storage – Up to 10,000 measurements.

The versatile SQ-520 can be used two ways – it can be connected directly to a computer for real-time measurements and data logging using the provided software, or it can be connected to a standard USB power source and act as a stand-alone datalogger capable of storing 10,000 periodic measurements internally that can be downloaded to a computer later for analysis. Back to Top

 

SQ-521: (SDI-12) Full-spectrum Quantum Sensor

The SQ-521 is a digital sensor with SDI-12 communication protocol. The sensor incorporates a rugged, self-cleaning sensor housing design, anodised aluminium body with acrylic diffuser. Typical applications include PPFD measurement over plant canopies in outdoor environments, greenhouses, and growth chambers, and reflected or under-canopy (transmitted) PPFD measurements in the same environments. Quantum sensors are also used to measure PAR/PPFD in aquatic environments, including salt water aquariums where corals are grown.

 

SQ-522: Modbus Digital Output Full-spectrum Quantum Sensor

The SQ-522 sensor outputs a digital signal using Modbus RTU protocol over RS-232 or RS-485. The sensor incorporates a rugged, self-cleaning sensor housing design, anodized aluminum body with acrylic diffuser, and high-quality cable terminating in pre-tinned pigtail leads for easy connection to dataloggers and controllers. Typical applications include PPFD measurement over plant canopies in outdoor environments, greenhouses, and growth chambers, and reflected or under-canopy (transmitted) PPFD measurements in the same environments. Quantum sensors are also used to measure PAR/PPFD in aquatic environments, including salt water aquariums where corals are grown. Back to Top

 


You can use the Quantum Sensor in a
Sensor-Node IoT Package (SNiP)

The SNiP-SQF is a ‘Sensor Node Integrated Package’ for LoRaWAN or CAT-M1 communication of real-time measurements of photons spread out in a particular area, for continuous plant, light and environmental monitoring.

The SNiP-SQF integrates 1x S-NODE and 1x SQ-521 PAR Sensor to a site’s unique network, communication and power requirements. The S-NODE can support an additional 3 compatible sensors. Back to Top

Typical applications include PPFD measurement over plant canopies in outdoor environments, greenhouses, and growth chambers, and reflected or under-canopy (transmitted) PPFD measurements in the same environments. Quantum sensors are also used to measure PAR/PPFD in aquatic environments, including salt water aquariums where corals are grown. Sensor includes IP68 marine-grade stainless-steel cable connector 30 cm from head to simplify sensor removal and replacement for maintenance and recalibration.

Rugged Design: The head is submersible and suitable for use in all climate conditions. Patented domed shaped sensor head (diffuser and body) facilitate runoff of dew and rain to keep the sensor clean and minimize errors caused by dust blocking the radiation path. Sensors are housed in a rugged anodised aluminium body and electronics are fully potted.

Excellent Cosine Response: Sensors measure PPFD with a cosine response accurate within ±5% at 75° zenith angle.

sq-500-spectral-responseRefined Spectral Response: The improved spectral response of the SQ-500 increases the accuracy of LED measurements, making it ideal for use with both natural and electric light sources.

Accurate, Stable Measurements: Calibration in controlled laboratory conditions is traceable to a NIST lamp. Quantum sensors are cosine-corrected, with directional errors less than ± 5% at a solar zenith angle of 75°. Long-term non-stability, determined from multiple replicate quantum sensors in accelerated aging tests and field conditions, is less than 2% per year.

Typical Applications: PPFD measurement over plant canopies in outdoor environments, greenhouses and growth chambers, and reflected or under-canopy (transmitted) PPFD measurements in the same environments. Quantum sensors are also used to measure PPFD in aquatic environments, including salt water aquariums where corals are grown.