ACQUIRING DATA
iKon-L SECTION 5
Page 67
To obtain the highest possible spectral rates the system can be configured to operate in Crop Mode. This
mode can be selected by clicking on the Crop Mode tab in the Setup Acquisition dialog box, the following
dialog box appears:
This mode is activated by clicking the tick box beside Enable Crop Mode. You can now enter a value in the
box labeled ‘Top’ within the Crop Settings dialog box. The value entered in this box specifies the number of
rows that will be read out and digitized to provide a spectrum.
The pixels outside of these specified rows are not readout between successive spectra, thus enabling high
spectral rates (>1kHz) to be achieved. It is therefore important to ensure that no light falls on the rows outside
of the specified area otherwise the digitized data will be corrupted by this stray light. Crop mode can operate
either in real time / video mode or be used to build a kinetic series of traces showing the temporal evolution of
an event.
For the example setup shown in the dialog box above, the twenty rows immediately above the horizontal shift
register will be the active region, i.e. the area that should be illuminated by the signal to be measured. The
remainder of the sensor (the excluded region) should be in darkness as any charge in these rows will be
progressively moved into and through the active region as spectra are readout.
Provided that the CCD sensor is adequately cooled, the high spectral rates mean that the dark current built up
in each spectra is negligible. However any stray light falling on the excluded region will corrupt the data
produced.
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