Chapter 5 General Operation Factors 65
Possible data loss if the total charge binned together exceeds the capacity of the
shift register or output node.
The possibility of blooming or data loss strongly limits the number of pixels that may be
binned in cases where there is a small signal superimposed on a large background, such as
signals with a large fluorescence. Ideally, one would like to bin many pixels to increase the
S/N ratio of the weak peaks but this cannot be done because the fluorescence would quickly
saturate the CCD. The solution is to perform the binning in software. Limited hardware
binning may be used when reading out the CCD. Additional post-processing binning is
accomplished in software, producing a result that represents many more photons than was
possible using hardware binning.
Full Frame CCD
Figure 21 shows an example of 2
2 binning for a full frame CCD.
Each pixel of the image displayed
by the software represents 4 pixels
of the CCD array. Note that in
WinSpec, Y-axis (slit) binning
occurs automatically: the Image
option must be installed and
selected for any other binning
format to be available.
Figure 21. 2 × 2 Binning for Full Frame CCD
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