Zeiss LSM 880 Operating Manual page 233

LSM 880
Please note that the cut off count rate is defined as a value exceeding the average count rate
during a certain measurement period (bin window) by a certain percentage. Thus, the consecutive
fast succession of low peaks might accumulate the same count rate as one high peak within a
certain period of time and hence, the cut off is not defined by the peak height but rather by the
counts per binning time.
Fig. 295
Dust filter
If the integrated count rate over a certain count interval will exceed the average count rate by that
threshold, this special interval is discarded for correlation analysis. For example, if the system detects a
count rate in a certain time interval that exceeds the average count rate by over 30 % and the threshold
was set at 30, this interval will be discarded for correlation analysis. The time intervals before and after
the discarded region are separately correlated and the results averaged. These holds also true, if more
than one region is discarded. In this case all the single regions that are separated by cut our regions are
separately correlated and the resulting average will be displayed.
Note, that calculation of an average will be performed at the beginning of the measurement. If
peak count rates will come at the beginning, this kind of dust filter does not work. Also, due to the
necessity to average signals over a certain integration time, more than only the peak area will be
discarded. Another outcome of the necessity to average the count rate signal is that several small
peaks following close to each other will be treated as a huge peak and might be cut out. This
means, in the Automatic cut mode accumulated count rates rather than peaks are removed. For
cross-correlation experiments, any of the regions discarded in either autocorrelation function will
not be used. Cut off regions are framed by stippled boxes and appear matted in the Count Rate
window.
10/2014 V_01
CHAPTER 1 - SYSTEM OPERATION
Left Tool Area and Hardware Control Tools
Count rate trace with cut out regions
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ZEISS
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