PicoQuant GmbH HydraHarp 400 Software V. 3.0.0.1
possible to shift the acquisition window relative to the sync frame by means of the offset. Note that working with
very long time spans (low sync rates) also requires long acquisition times to mimnimize noticeable “steps” in
the acquired histograms.
Acquisition Time edit box and spin control
Set the desired measurement time here. Units are Seconds (s). The permitted range is 0.001 to 360,000 in
steps of 0.001. Type the desired value in the edit box and press <Enter> or click on Apply. Alternatively, use
the spin control (next to it) to increment / decrement the current value. In this case, changes take effect
immediately without pressing <Enter>. The default increment / decrement per mouse click is logarithmic.
Offset edit box and spin control
For sync rates > 20 MHz the highest resolution is usually most appropriate, since the smallest range still covers
the full sync period. The offset should in these cases always be set to 0.
For lower sync rates the histogram range may be too small to cover the full sync period. The decay curve
region of interest may therefore lie outside the acquisition window of 65,536 channels. Apart from switching to
a lower resolution it is possible to shift the acquisition window relative to the sync frame by means of setting the
offset > 0.
Use this set of input controls to specify the desired offset. Units are Nanoseconds (ns). Possible offsets are in
the range from 0 to 500 ns. Type the value as an integer in the edit box and press <Enter> or click on Apply.
The offset value can be entered in steps of nanoseconds. Alternatively, use the spin control next to the edit box
to increment ⁄ decrement the current value. In this case changes take effect immediately without pressing
<Enter>.
Internally the offset is subtracted from each start–stop measurement before it is used to address the histogram
channel to be incremented. Therefore, increasing the offset means shifting the signal on the screen to the left,
towards earlier times.
Note that the offset has no effect on the relative timing of laser pulses and photon events. It merely shifts the
region of interest where data is to be collected. The relative timing of laser pulses and photon events can only
be controlled by means of cable delays (e.g. in order to shift your fluorescence decay within the sync frame so
that it is not truncated).
Trc./Block trace colour indicator, edit box and spin control
The HydraHarp can measure histograms in up to 512 memory blocks. Out of these, up to 8 curves can be
displayed and one "active block" can be used for measurements. Choose the active memory block you wish to
use for the next measurement here. The trace mapping dialog is used to select the curves for display. Make
sure the curve you are using is switched on (shown). You can open this dialog directly by clicking on the trace
colour indicator. The colour indicator shows the trace colour the chosen block is currently mapped to. If it is a
solid square, the curve is mapped and shown. If it is mapped but not shown, the indicator shows a small striped
square. If the curve is not even mapped for display the indicator remains white. Make sure not to overwrite
existing data in a block that was used before. In order to warn you if a trace is used, the heading of the
Trc/Block selector will turn red.
Restart check box
If this box is ticked (checked) the measurement will automatically restart after the acquisition time has elapsed.
Toggle the current setting with a mouse click. The setting is without effect in TRES mode.
Stop on Overflow check box
If this box is ticked (checked) the measurement will stop on overflow of any histogram bin. The overflow limit is
set by the "Stop At" parameter. Toggle the current setting with a mouse click.
Mode selection box
You may here select between three different acquisition modes:
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