Ocean Optics Dragon - Manual (Page 15)

Chapter 3: Quantum Software Icons
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Integration time
Integration time is the exposure time for each pixel in the array. Each of the pixels is “read” in turn and
the time between readings controls the amount of charge in each CCD sensor. The charge decreases with
every photon than hits the sensor, so if there are not many photons around it takes a long time to reduce
the charge. Too many photons will discharge the sensor completely in a short time.
If the time is too long, the sensors will saturate and the spectrum line will go off scale. This does not harm
the sensor, but the data you collect will have no value. If, for example, you want to find detail in low
intensity emission peaks, but there are high intensity peaks in the same spectrum, then increase the
integration time and zoom in to the part of the spectrum you want to look at.
For very dim sources a longer integration time is needed, but the penalty is more noise for less signal. The
default integration time is 100 ms.
As reference sources are usually brighter than sample sources then setting an integration time that gives a
y-axis value of just under full scale normally works well.