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-SSSQ-512-SSSQ-514-SSSQ-515-SSSQ-520SQ-521-SSSQ-522-SS
Power SupplySelf-powered5 to 24 V DC12 to 24 V DC5.5 to 24 V DC5 V USB power source5.5 to 24 V DC5.5 to 24 V DC
Current Draw-At 12 V is 57 µAmaximum of 20 mAAt 12 V is 57 µA61 mA when logging1.4 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-10.625 mV per µmol m-2 s-10.004 mV per µmol m-2 s-11.25 mV per µmol m-2 s-1---
Output Type0 to 40 mV0 to 2.5 mV4 to 20 mA0 to 5 VUSBSDI-12Modbus
Resolution----0.1 µmol m-2 s-1--
Calibration Factor (reciprocal of sensitivity)100 µmol m-2 s-1 per mV1.6 µmol m-2 s-1 per mV250 µmol m-2 s-1 per mA0.8 µmol m-2 s-1 per mVCustom for each sensor and stored in the firmwareCustom for each sensor and stored in the firmwareCustom for each sensor and stored in the firmware
Calibration Uncertainty± 5 %± 5 %± 5 %± 5 %± 5 %± 5 %± 5 %
Measurement RepeatabilityLess 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 YearLess than 2 % per yearLess than 2 % per yearLess than 2 % per yearLess than 2 % per yearLess than 2 % per yearLess than 2 % per yearLess than 2 % per year
Non-linearityLess 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 TimeLess than 1 msLess than 1 msLess than 1 msLess than 1 msSoftware updates every secondLess than 0.6 s-
Field of View180°180°180°180°180°180°180°
Spectral Range389 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 SelectivityLess than 10 % from 412 to 682 nm ± 5 nmLess than 10 % from 412 to 682 nm ± 5 nmLess than 10 % from 412 to 682 nm ± 5 nmLess than 10 % from 412 to 682 nm ± 5 nmLess than 10 % from 412 to 682 nm ± 5 nmLess than 10 % from 412 to 682 nm ± 5 nmLess 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
Dimensions24 mm diameter, 37 mm height30.5 mm diameter, 37 mm height30.5 mm diameter, 37 mm height30.5 mm diameter, 37 mm height24 mm diameter, 37 mm height30.5 mm diameter, 37 mm height30.5 mm diameter, 37 mm height
Mass (5 m of cable)100 g140 g140 g140 g100 g140 g140 g

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