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SQ-644-SS 4-20 mA output Quantum Light Pollution Sensor

Updated:2025-03-13

Brand: Apogee
Model: SQ-644-SS
Description: The SQ-644 Quantum Light Pollution is an amplified sensor with a 4 to 20 mA output. The sensor features a rugged, aluminum housing that is fully-submersible and built to withstand harsh conditions, an
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Product Details

Overview of SQ-644-SS 4-20 mA output Quantum Light Pollution Sensor：

User's Manual

The SQ-644 Quantum Light Pollution is an amplified sensor with a 4 to 20 mA output. The sensor features a rugged, aluminum housing that is fully-submersible and built to withstand harsh conditions, and high-quality cable terminating in pre-tinned pigtail leads for easy connection to dataloggers and controllers. The sensor cable includes an IP68 marine-grade stainless-steel cable connector to simplify sensor removal and replacement from permanent installations for maintenance and calibration. Typical applications of Quantum Light Pollution sensors include incoming PFD measurements over plant canopies in indoor greenhouses or in growth chambers, and reflected or under-canopy (transmitted) PFD measurements in the same environments.

The analog version of this sensor (SQ-640) comes with the inline cable connector placed 30 cm from the sensor head for either standard use as a long-cable pigtail sensor, or for use with our microCache Bluetooth Micro Logger by unscrewing the connector, discarding the long section of cable and then screwing the sensor to the mating connector on the microCache.

SQ-644-SS Sensor Drawing：

Specifications of SQ-644-SS:

Power Supply	12 to 24 V DC
Current Draw	Maximum of 20 mA
Sensitivity	0.08 mA per μmol mˉ2 sˉ1
Calibration Factor	12.5 μmol mˉ2 sˉ1 per mA
Calibration Uncertainty	± 5 %
Output Range	4 to 20 mA
Measurement Range	0 to 200 μmol mˉ2 sˉ1
Measurement Repeatability	Less than 0.5 %
Long-term Drift (Non-stability)	Less than 2 % per year
Non-linearity	Less than 1 % (up to 200 μmol mˉ2 sˉ1)
Response Time	Less than 1 ms
Field of View	180?
Spectral Range	340 to 1040 nm ± 5 nm (wavelengths where response is greater than 50 %)
Directional (Cosine) Response	± 2 % at 45°, ± 5 % at 75° zenith angle
Azimuth Error	Less than 0.5 %
Tilt Error	Less than 0.5 %
Temperature Response	-0.11 ± 0.04 % per C
Uncertainty in Daily Total	Less than 5 %
Housing	Anodized aluminum body with acrylic diffuser
IP Rating	IP68
Operating Environment	-40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m
Dimensions	30.5 mm diameter, 37 mm height
Mass (with 5 m of cable)	140 g
Cable	5 m of two conductor, shielded, twisted-pair wire; TPR jacket; pigtail lead wires; stainless steel (316), M8 connector
Warranty	4 years against defects in materials and workmanship
Manufactured	Made in the USA