6
SPECIFICATIONS
Calibration Traceability
Apogee Instruments SQ-500 series quantum sensors are calibrated through side-by-side comparison to the mean of four
Apogee model SQ-500 transfer standard quantum sensors under high output T5 cool white fluorescent lamps. The transfer
standard quantum sensors are calibrated through side-by-side comparison to the mean of at least three LI-COR model LI-
190R reference quantum sensors under high output T5 cool white fluorescent lamps. The reference quantum sensors are
recalibrated on a biannual schedule with a LI-COR model 1800-02 and quartz halogen lamp that is traceable to the National
Institute of Standards and Technology (NIST).
SQ-520
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 Range
0 to 4000 µmol m
-2
s
-1
Measurement Repeatability
Less than 1 % (up to 4000 µmol m
-2
s
-1
)
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
Software updates every second
Field of View
180º
Spectral Range
389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %)
Spectral Selectivity
Less than 10 % from 412 to 682 ± 5 nm (see Spectral Response below)
Directional (Cosine) Response
± 2 % at 45º zenith angle, ± 5 % at 75º zenith angle (see Cosine Response below)
Temperature Response
-0.11± 0.03 % per C (see Temperature Response below)
Azimuth Error
Less than 0.5 %
Tilt Error
Less than 0.5 %
Detector
Blue-enhanced silicon photodiode
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
24 mm diameter, 37 mm height
Mass
Sensor head weighs 90 g
USB Cable
4.6 m (15 ft)
Current Draw (when Logging)
61 mA