Sensor Calibration
Apogee SQ-640 Quantum Light Pollution Sensors have standard calibration factors of exactly:
1 µmol m
-2
s
-1
per mV
Multiply the calibration factor by the measured mV signal to convert sensor output to photon flux density in units
of µmol m
-2
s
-1
:
Calibration Factor (1 µmol m
-2
s
-1
per mV) * Sensor Output Signal (mV) = Photon Flux Density (µmol m
-2
s
-1
)
1
* 50
= 50
Example of photon flux density measurement with an
Apogee model SQ-640 Quantum Light Pollution Sensor.
The LED in this example Full yields a photon flux density on
a horizontal plane of 50 µmol m
-2
s
-1
. This yields an output
signal of 50 mV. This signal is converted to photon flux
density by multiplying by the calibration factor of 1
mol
m
-2
s
-1
/ mV.
LED Output
(50 µmol m
-2
s
-1
)
Sensor Output
50 mV