The SQ-224 is an amplified original quantum sensor with a 4 to 20 mA output that has been calibrated for use with electric lights. The sensor was designed for use in environments with significant background electrical noise that can be found in many industrial applications. The sensor features a rugged, self-cleaning sensor housing design. Typical applications include PPFD (Photosynthetic Photon Flux Density) 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 (Photosynthetically Active Radiation)/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.
Power Supply 7 to 24 V DC with a maximum current draw of 22 mA (2 mA quiescent current draw)
Sensitivity 0.004 mA per µmol mˉ² sˉ¹
Calibration Factor 250 µmol mˉ² sˉ¹ per mA (reciprocal of sensitivity)
Calibration Uncertainty ± 5 %
Calibrated Output Range 4 to 20 mA
Measurement Repeatability Less than 0.5 %
Non-stability (Long-term Drift) Less than 2 % per year
Non-linearity Less than 1 % (up to 4000 µmol mˉ² sˉ¹ )
Response Time Less than 1 msField of View180 ˚
Spectral Range 410 nm to 655 nm (wavelengths where response is greater than 50 % of maximum)
Spectral Selectivity Less than 10 % from 469 to 655 nm
Directional (Cosine) Response ± 5 % at 75 ˚ zenith angle
Temperature Response 0.06 ± 0.06 % per C
Operating Environment -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m
Dimensions 24 mm diameter, 28 mm height
Mass 100 g (with 5 m of lead wire)
Cable 5 m of shielded, twisted-pair wire with TPR jacket (high water resistance, high UV stability, flexibility in cold conditions)
Warranty 4 years against defects in materials and workmanship
