Zeiss LSM 880, Operating Manual

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CHAPTER 1 - SYSTEM OPERATION
ZEISS Left Tool Area and Hardware Control Tools LSM 880
224 000000-2071-464 10/2014 V_01
5.3.5 Setup – Correlator
In the Correlator tool you can define the fit and
acquisition parameters for the measurement.
•
Click on the Correlation tab to open the
Correlation
panel (Fig. 291). Click on any other
tab to leave the panel.
All changed settings can be reset to the default
settings by pressing the
Default
button.
You have the following options:
(1) Correlation
The Correlation panel allows you to specify, how the raw data will be processed for correlation analysis.
•
Click on the Correlation tab (Fig. 291) to open the Correlation panel. Click any other tab to leave
the panel.
Here you can set the initial correlator
Binning time (in µs), the initial number of direct Tau channels and
the maximum Tau time used for the Multiple Time Algorithm. Adjust the numbers in the Binning (in µs),
Maximum correlation time (in s) and Tau Channels display boxes, respectively. You can either directly
enter values or use the arrows. Default values can be entered individually by pressing the
0.2
,
1000
and
8
buttons. Please note that with the default settings, the algorithm works the fastest.
The correlator Binning time determines the minimal bin time used in the correlation analysis and
also the start correlation time, which will be identical to minimal bin time.
The Maximum correlation time defines the end correlation time. It cannot exceed the
measurement time. Hence, the value will only be used if equal to or smaller than 2/3 of the
measurement time, if greater 2/3 of the measurement time will be used automatically.
The correlator Tau channels define the number of linear increased Tau channels per multiple Tau
step.
The algorithm for auto-correlation functions is as follows. In the first correlation step all events
within a certain correlation interval T are counted. The default T in the first correlation step (n=0)
equals 200 ns, which is 4x the maximum sampling rate of 50 ns, as limited by the dead time of the
APDs and the electronics. T will be changed by the entry in the
Binning display window. This
corresponds to a clock speed of 20 MHz. Thus, for this correlation interval a maximum of 4 events
can be counted. These events / correlation intervals are shifted against themselves for a time
interval t. The first t equals the first T value, as a default 200 ns = 0.2 ms. t will be changed by the
entry in the
Binning display window. T is linearly increased by step sizes of 200 ns (or the entered
value) for 8 times (direct tau) and than for another 8 times (multiple Tau), i.e. the maximum
correlation time in the first step is 16 x 0.2 ms =3.2 ms using the default settings. The direct and
shifted events / correlation intervals are multiplied interval for interval and the products are added
Fig. 291 Correlator tool – Correlation active