SPECIFICATIONS
Calibration Traceability
Apogee SQX series quantum sensors are calibrated through side-by-side comparison to the mean of transfer
standard quantum sensors under a reference lamp. The reference quantum sensors are recalibrated with a 200 W
quartz halogen lamp traceable to the National Institute of Standards and Technology (NIST).
SQ-420X
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 0.5 %
Long-term Drift
(Non-stability)
Less than 2 % per year
Non-linearity
Less than 1 % (up to 2500 µmol m
-2
s
-1
)
Response Time
Software updates every second
Field of View
180°
Spectral Range
370 to 650 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
-0.04 % per C (see Temperature Response below)
Operating Environment
10 to 60 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
Sensor head weighs 90 g
USB Cable
4.5 m (15 ft)
Current Draw (when
Logging)
61 mA
