The SQ-420 sensor can be connected to a desktop, laptop, or tablet computer via USB 2.0 type A plug, to be used with the Apogee software. The included Apogee software gives the user control of data logging and calibration settings, as well as providing a real time output display and graph of PPFD measurements, and also allowing the data set to be saved as a csv file.
The SQ-420 is a stand-alone PAR sensor/datalogger with 10,000 measurement internal data storage that can be uploaded to a computer. If continuously connected, the software graphs real-time PPFD.
|The SQ-420 is used to measure incoming and reflected PPFD around plants and other organisms in outdoor environments, greenhouses, growth chambers, and underwater.
Internal Data Storage
|No External Datalogger Required.|
The SQ-420 is calibrated independently for sunlight and electric light to improve measurement accuracy. The light source calibration can be selected in the settings menu of the Apogee software.
|Resolution:||0.1 µmol m-2 s-1|
|Calibration Factor:||Custom for each sensor and stored in the firmware|
|Calibration Uncertainty:||±5% (see Calibration Traceability below)|
|Measurement Repeatability:||Less than 1%|
|Non-stability (Long-term Drift):||Less than 2% per year.|
|Non-linearity:||Less than 1% (up to 3000 µmol m-2 s-1)|
|Response Time:||Software updates every second.|
|Field of View:||180°|
|Spectral Range:||410 nm to 655 nm (wavelengths where response is greater than 50% of maximum; see Spectral Response below)|
|Directional (Cosine) Response:||±5% at 75° zenith angle (see Cosine Response below)|
|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 30m|
|Dimensions:||2.4cm diameter and 2.8cm height|
|Mass:||Sensor head weighs 90g|
|USB Cable:||4.6m (15 ft)|
|Current Draw (when Logging):||0.35mA|
The versatile SQ-420 can be used two ways – it can be connected directly to a computer for real-time measurements and data logging using the provided software, or it can be connected to a standard USB power source and act as a stand-alone datalogger capable of storing 10,000 periodic measurements internally that can be downloaded to a computer later for analysis.
Apogee Instruments Quantum Sensors consist of a cast acrylic diffuser (filter), photodiode, and signal processing circuitry mounted in an anodised aluminium housing, and a cable to connect the sensor to a measurement device. The sensor is potted solid with no internal air space. It is designed for continuous PPFD measurement in indoor, outdoor, and underwater environments. The SQ-420 sensor output increases linearly with PPFD under sunlight (natural setting) or electric lights (electric setting). The signal from the sensor is directly proportional to radiation incident on a flat surface where the radiation comes from all angles of a hemisphere.