Pre-Acquisition Setup - CCD
5.3.1.5 - Cropped Sensor Mode
If an experiment demands the fastest image or spectrum acquisition rates, but cannot be constrained by the maximum
storage size of the sensor (as is the case for ‘Fast Kinetics Mode’), a specic ‘Cropped Sensor Mode’ can be set up
through the main acquisition set up window, e.g.:
In this mode, the user denes a ‘sub-array’ size from within the full image sensor area, such that it encompasses the
region of the image where change is rapidly occurring. The sensor subsequently ‘imagines’ that it is of this smaller dened
array size, achieved through software executing special readout patterns, and reads out at a proportionally faster frame
rate. The smaller the dened array size, the faster the frame rate achievable.
The cropped area must be positioned in the bottom-left of the sensor, thus the subject of study should be rst positioned
in this area rather than centrally located.
Note: Special offset anges for Andor spectrographs are available so that crop area of the sensor is positioned
across the spectrograph optical axis, where best optical performance can be achieved.
Note: When using crop mode, care should be taken to avoid (or greatly minimize) stray light falling on the top of
the sensor, i.e. outside the active ‘cropped’ area of the sensor, in order to avoid useful signal corruption.
Note: The use of Andor’s Optomask for imaging applications should be considered to physically block unwanted
light falling on to the upper part of the sensor.
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