The SQ-222 is an amplified original quantum sensor with a 0 to 2.5 V output that has been calibrated for use with electric lights. 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.
PAR Measurements Characterize Tree Coverages
Using line quantum meter to study the percent of PAR (under canopy/open sky) and its relation to survival and initial growth of native forest species.
Controlling Flowering of Orchids in Greenhouse
Line quantum sensor used to measure PPFD and daily light integral, while experimenting with temperature to control flowering.
Power Supply 3.3 to 24 V DC; current draw 10 µA Sensitivity 1 mV per µmol mˉ² sˉ¹ Calibration Factor 1 µmol mˉ² sˉ¹ per mV (reciprocal of sensitivity) Calibration Uncertainty ± 5 % Calibrated Output Range 0 to 2.5 V Measurement Repeatability Less than 0.5% Non-stability (Long-term Drift) Less than 2 % per year Non-linearity Less than 1 % (up to 2500 µmol mˉ² sˉ¹; maximum PPFD measurement is 2500 µmol mˉ² sˉ¹) Response Time Less than 1 ms Field of View 180˚ 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, 33 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