Apogee Instruments’ Full-Spectrum Quantum PAR sensors and PAR meters are the industry standard for accurately measuring photosynthetically active radiation (PAR or PPFD) from all light sources used to grow plants and corals.
Spectral Response
Our full-spectrum quantum PAR sensors and PAR meters have a highly optimized photo detector that accurately measures the photosynthetic radiation spectral range of 400 to 700 nm. These are our top of the line models that measure accurately under all light sources including narrow-band LEDs. The exact spectral response of our full-spectrum models can be seen in the graph below.
Accurate, Stable Measurements
Sensors are cosine-corrected to maintain their accuracy when radiation comes from low zenith angles. The sensors measure PPFD with a cosine response accurate within ± 5 % at 75° zenith angle. Long-term non-stability determined from multiple replicate quantum sensors in accelerated aging test and field conditions is less than 2 % per year.
Typical Applications
PPFD measurements over plant canopies in outdoor environments, greenhouses, growth chambers, and reflected or under-canopy (transmitted) PPFD measurements in the same environments. Apogee Quantum sensors can also be used to measure PPFD in aquatic environments, including saltwater aquariums where coral reefs are grown.
Rugged, Self-cleaning Housing
The patented domed-shaped sensor head sheds dew, rain, and dust to keep the sensor clean and minimize errors. Sensor housings are made from rugged anodized aluminum and filled with electronics-grade epoxy potting compound to prevent any water ingress.
Ideal for Measurements in both Air and Water
All Apogee quantum sensor heads are waterproof. Most sensors are calibrated to make absolute PPFD measurements in air, while some are specially calibrated to make measurements underwater by applying an immersion correction factor. For details on making underwater measurements, please refer to Underwater PAR Measurements.
Calibration
To ensure accuracy, each sensor is carefully calibrated for all light sources in controlled conditions that are traceable to NIST reference standards.
Mounting
The AL-120 Solar Mounting Bracket with Leveling Plate makes mounting the sensor to a mast or pipe easy. The AL-100 Solar Sensor Leveling Plate is designed to level the sensor while sitting on a flat surface or mounting to other fixtures.
Output Options
Pigtail sensors are available in multiple analog output options including 0 to 40 mV, 0 to 2.5 V, 0 to 5 V, and 4 to 20 mA. Digital output options include a digital USB “smart” sensor with custom software, SDI-12, and Modbus. Sensors are also available attached to a hand-held meter with digital readout. The analog version of this sensor (SQ-500) works with our µCache Bluetooth Micro Logger.
High-Quality Cable
Pigtail sensors feature an IP68, marine-grade stainless-steel cable connector to simplify sensor removal for maintenance and recalibration. The cable is shielded-twisted-pair wire with a TPR jacket for high water resistance, UV stability, and flexibility in cold conditions.
Technical Specifications
| SQ-500-SS | SQ-512-SS | SQ-514-SS | SQ-515-SS | SQ-520 | SQ-521-SS | SQ-522-SS | |
|---|---|---|---|---|---|---|---|
| Power Supply | Self-powered | 5 to 24 V DC | 12 to 24 V DC | 5.5 to 24 V DC | 5 V USB power source | 5.5 to 24 V DC | 5.5 to 24 V DC |
| Current Draw | - | At 12 V is 57 µA | maximum of 20 mA | At 12 V is 57 µA | 61 mA when logging | 1.4 mA (quiescent); 1.8 mA (active) | RS-232 37 mA; RS-485 quiescent 37 mA, active 42 mA |
| Output (Sensitivity) | 0.01 mV per µmol m-2 s-1 | 0.625 mV per µmol m-2 s-1 | 0.004 mV per µmol m-2 s-1 | 1.25 mV per µmol m-2 s-1 | - | - | - |
| Output Type | 0 to 40 mV | 0 to 2.5 mV | 4 to 20 mA | 0 to 5 V | USB | SDI-12 | Modbus |
| Resolution | - | - | - | - | 0.1 µmol m-2 s-1 | - | - |
| Calibration Factor (reciprocal of sensitivity) | 100 µmol m-2 s-1 per mV | 1.6 µmol m-2 s-1 per mV | 250 µmol m-2 s-1 per mA | 0.8 µmol m-2 s-1 per mV | Custom for each sensor and stored in the firmware | Custom for each sensor and stored in the firmware | Custom for each sensor and stored in the firmware |
| Calibration Uncertainty | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % |
| Measurement Repeatability | Less than 0.5 % | Less than 1 % | Less than 0.5 % | Less than 1 % | Less than 0.5 % | Less than 1 % | Less than 1 % |
| Long-term Drift per Year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % 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) | 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) | Less than 1 % (up to 4000 µmol m-2 s-1) |
| Response Time | Less than 1 ms | Less than 1 ms | Less than 1 ms | Less than 1 ms | Software updates every second | Less than 0.6 s | - |
| Field of View | 180° | 180° | 180° | 180° | 180° | 180° | 180° |
| Spectral Range | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %) | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %) | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %) | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %) | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %) | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %) | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %) |
| Spectral Selectivity | Less than 10 % from 412 to 682 nm ± 5 nm | Less than 10 % from 412 to 682 nm ± 5 nm | Less than 10 % from 412 to 682 nm ± 5 nm | Less than 10 % from 412 to 682 nm ± 5 nm | Less than 10 % from 412 to 682 nm ± 5 nm | Less than 10 % from 412 to 682 nm ± 5 nm | Less than 10 % from 412 to 682 nm ± 5 nm |
| Directional (Cosine) Response | ± 5 % at 75° zenith angle | ± 2 % at 45°; ± 5 % at 75° | ± 2 % at 45°; ± 5 % at 75° | ± 2 % at 45°; ± 5 % at 75° | ± 5 % at 75° zenith angle | ± 2 % at 45°; ± 5 % at 75° | ± 2 % at 45°; ± 5 % at 75° |
| Temperature Response | -0.11 ± 0.04 % per C | -0.11 ± 0.04 % per C | -0.11 ± 0.04 % per C | -0.11 ± 0.04 % per C | -0.11 ± 0.04 % per C | -0.11 ± 0.04 % per C | -0.11 ± 0.04 % per C |
| 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 | -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 | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m |
| Dimensions | 24 mm diameter, 37 mm height | 30.5 mm diameter, 37 mm height | 30.5 mm diameter, 37 mm height | 30.5 mm diameter, 37 mm height | 24 mm diameter, 37 mm height | 30.5 mm diameter, 37 mm height | 30.5 mm diameter, 37 mm height |
| Mass (5 m of cable) | 100 g | 140 g | 140 g | 140 g | 100 g | 140 g | 140 g |
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