Apogee SQ-520 Full Spectrum Underwater Quantum PAR Sensor (USB)
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Product Description: 

The new SQ-520 full-spectrum, smart quantum sensor can be connected directly to a computer via USB for taking spot measurements or graphing and datalogging real-time PPFD using the included software. The sensor can also act as a stand-alone PAR datalogger by simply connecting it to any standard 5 V DC USB power plug. Internal memory within the sensor head is capable of storing 10,000 user-specified periodic measurements that can be downloaded as a CSV file to a computer for analysis.

Full-spectrum Sensor 

Features an improved detector that provides excellent measurements under all light sources, including LEDs, right out of the box. The full-spectrum quantum sensor has a spectral range of 389 to 692 nm ± 5 nm seen in graph to the left. The sensor is available attached to a hand-held meter that provides a digital readout (MQ-510), with USB communication and custom software (SQ-520), and in multiple analog outputs to be used with a datalogger or voltmeter. 


Ready for Underwater Use

All Apogee Underwater Quantum Meters and Sensors models (MQ-210, MQ-510, SQ-520) have the immersion effect correction factor preprogramed in the firmware or sensor software allowing the user to make excellent underwater measurements right out of the box. Sensors feature a waterproof sensor head that is potted solid for a complete seal and to ensure it has no hollow cavities for water to penetrate and cause measurement errors. 

How is the SQ-520 different from previous Apogee quantum sensors? 

The SQ-520 performs exactly the same underwater as the MQ-500 series, but the SQ-520 simply multiplies the PAR reading by 1.32 to account for the immersion effect. The SQ-520 is a full-spectrum quantum sensor (SQ/MQ-500 Series) with a spectral range of 389 to 692 nm ± 5 nm, which can be seen in the graph below. This improved spectral response increases the accuracy of LED measurements.


Datalogging Capabilities 

The SQ-520 USB sensor has internal memory capable of storing 10,000 user-specified periodic measurements that can be downloaded to a computer. 

Where is the SQ-520 used? 

The SQ-520 is used to measure incoming and reflected PPFD around plants and other organisms in outdoor environments, greenhouses, growth chambers, and underwater.

Calibration Uncertainty ± 5 %
Measurement Range 0 to 4000 µmol m-2 s-1
Measurement Repeatability Less than 0.05 %
Long-term Drift (Non-stability) Less than 2 % per year
Non-linearity Less than 1 % (up to 4000 µmol m-2 s-1)
Response Time Less than 1 ms
Field of View 180 °
Spectral Range 389 to 692 nm ± 5 nm ( wavelengths where responsis greater than 50 %)
Spectral Selectivity Less than 10 % from 412 to 682 nm ± 5 nm
Directional (Cosine) Error Less than ± 5 % at 75° zenith anglean 10 % from 412 to 682 nm ± 5 nm
Azimuth Error Less than 0.5 %
Tilt Error Less than 0.5 %
Temperature Response -0.11 ± 0.04 % C-1
Uncertainty in Daily Totals Less than 5 %
Detector Blue-enhanced silicon photodiode
Housing Anodized aluminum body with acrylic diffuser
IP Rating IP68
Operating Environment 0 to 50 C; less than 90 % non-condesing relative humidity up to 30 C; less than 70 % non-condensing relative humidity from 30 to 50 C; separate sensors can be submerged in water up to depths of 30 m
Meter Dimensions 126 mm length; 70 mm width; 24 mm eight
Sensor Dimensions 24 mm diameter; 37 mm height
Mass 180 g
Cable 2 m of two conductor, shielded, twisted-pair wire; addititonal cable wire available; santoprene rubber jacket