Apogee Instruments SE-100 Owner's Manual - Page 13

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Sensor Calibration

The Apogee unamplified photometric sensor model SE-100 has a standard illuminance (lux) calibration factor of

exactly:

Multiply this calibration factor by the measured mV signal to convert sensor output to illuminance in units of lux:

Calibration Factor (1000 lux per mV) * Sensor Output Signal (mV) = lux (lm m

1000

Full Sunlight

(120000 lux)

Spectral Errors

The combination of the filter and photodiode in Apogee photometric radiometers is designed to provide a spectral

response that matches the CIE 1931 photopic luminosity function. Mismatch between radiometer spectral

response and the photopic luminosity function results in spectral errors for light sources that differ from the

source used to calibrate the radiometer. The table below provides spectral error estimates for illuminance

measurements with Apogee photometric radiometers under various light sources.

1000 lux per mV

Sensor Output

120 mV

120

Example of illuminance measurement with an

Apogee photometric sensor. Full sunlight yields

an illuminance on a horizontal plane at the

Earth's surface of approximately 120000 lux.

This yields an output signal of 120 mV. The

signal is converted to illuminance by

multiplying by the calibration factor of 1000 lux

per mV.

-2

)

120000