Why using a DA Beamsplitter/combiner for correction of the Drift? When measuring the transmission of a reference solution against time, the output should in theory remain 100% transmission. In practice this output value will not remain exactly fluctuating around 100% transmission, but the signal will slowly drift away. The reason for this drift is a combination of drift caused by the lightsource and drift of the spectrometer. Drift of the lightsource can be caused by warming up or aging over time or different flashes in case of a Xenon Flash source. Drift of the spectrometer can be caused by a change of the temperature in the optical bench which causes micro bending of the components inside. The correct for drift function in AVAsoft will now use the changes in the reference signal to make a correction on the signal of the channel which measures the sample. Click HERE for this set up, with a flowcell.