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Original factory packaging
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Instrument Expert
Original factory packaging
Service Hotline：
(+86)010-52867771
Updated:2025-03-13
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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.
| 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 |
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