What Is a Dark Signal

Dark signal is the raw signal from the detector when no light enters the detector. This is the base raw signal level of the system.

NIRONE Sensors use Extended Indium-Gallium-Arsenide (Ext-InGaAs) IR detectors as part of the core technology. The InGaAs detectors are semiconductor-type IR detector units. This means that they respond to all thermal radiation within their use range, and not all of the detected signal is true response signal. The dark signal is a combination of the detector dark current (thermally generated signal), and partly of the stray light entering the detector. Measuring the level of the dark signal thus allows to remove this varying but stable signal level from the total signal. The RMS noise level of the dark signal is increased when the temperature of the detector is increased. This is due to the nature of the InGaAs detector.

The dark signal typically stabilises very fast after the measurement system has been turned on. Acquire a dark signal level at the beginning of the measurements, or use the Auto lamp with dark subtraction lamp, when using the integrated light sources of the NIRONE Sensors. In both of these cases, let the sensor run and stabilize for at least 5 to 15 minutes after the sensor has been started.


The SensorControl software will not allow you to display or save the absorbance unit values from measurements, unless the dark signal has been saved.