Zeiss LSM 880, Operating Manual

Page: 196 / 690

CHAPTER 1 - SYSTEM OPERATION
ZEISS Left Tool Area and Hardware Control Tools LSM 880
190 000000-2071-464 10/2014 V_01
5.3.3 Setup – Acquisition
Measure Time [s]
The
Measure Time
(Fig. 271) is the period of
one
measurement. As a rule of thumb the
measurement time should be about 1000 x the
diffusion time of a molecule under study. However,
due to noise in the system a 10 s measurement
time is a good start value to obtain good statistical
results. Enter a number in seconds in the input box
or use the scroll arrows.
Note that the laser power set under
Measurement / Pinhole Adjust
in the
System Configuration Laser panel will be
used for the measurement. If no laser was
activated but a measurement time entered,
the system gives a warning. Confirm the
warning if you want to continue anyway.
Repetitions
The Repetitions value determines the number of measurements, i.e. how often Measure Time is to be
performed within the measurement. Enter a value in the input box or use the scroll arrows.
Note that repetitions can be averaged into an average correlation function if required. This will
improve statistics. An average of 10 x 10 seconds measurement is not but nearly as good as one
100 sec measurement. If bleaching becomes a problem, it might help to reduce measurement time
and increase repetitions to obtain nearly as good statistical results while reducing bleaching.
Bleach Time (s)
The Bleach Time is the time prior to the measuring procedure during which the laser already has an
effect on the sample. It is used to pre-bleach the sample, for example to bleach away immobile molecules
that would not contribute to the correlation and would affect the correlation amplitude negatively.
The
Bleach Time is taken into consideration only once (at the beginning of a measuring cycle). Enter a
value in seconds in the input box or use the scroll arrows.
Note that the laser power set under
Bleach
in the
System Configuration Laser panel
will be
used for the bleach. If no bleach laser was activated but a bleach time entered, the system gives a
warning. Confirm the warning if you want to continue anyway.
Procedure for setting the times for an experiment:
•
Set the Bleach Time .
Start with the
Bleach Time
of 0 s. If the signal decreases during the subsequent measurement, this
might be caused by bleaching. As a remedy, you can pre-bleach the sample before measurement by
setting the
Bleach Time to a non-zero value. If no laser check box was activated, no bleaching
occurs, but the measurement will be delayed for the bleach time.
Fig. 271 Acquisition tool