Andor Technology iXon Ultra 897 User Manual page 151

TUTORIAL 2
Extending Dynamic Range in 'Slow Scan' Measurements By
Accumulating Signal
Although the iXon camera, due to it's high-speed operation and ultimate
Background
EMCCD sensitivity performance, is very well suited to dynamic low light
measurements, it can just as readily be applied to 'slow scan' non-dynamic
quantitative measurements such as microtitre plate, gel or biochip reading.
Operation under conditions of applied gain can enable very weak signals to
be amplified above the camera read noise (this can be particularly pertinent
in chemiluminescence / bioluminescence measurements), using lower
exposure times than would otherwise need to be employed.
However, such formats can typically be demanding on dynamic range,
requiring extremely weak signals to be imaged in the same frame as
significantly stronger signals. Whilst the iXon can deliver true 14 bit
dynamic range at 5 MHz readout, due to an extended full well capacity in
the gain register (enabling a degree of gain to be applied before saturation),
this may sometimes not be enough.
The object of this tutorial, is to outline the method by which both very
Aim
weak signals, and much stronger signals, may be quantitatively determined
in an image, without saturating the pixels of the CCD with the stronger
signal. .
Description
The first stage is to define the maximum exposure time (E1) at a given gain
setting, at which the strongest signal may be quantitatively measured before
the pixels become saturated. This can be accomplished by recording an
image at a given exposure time and measuring from one or two pixels
within the most intense signal. From the Acquisition menu on the Main
Window, select Setup Acquisition. In the Setup CCD tab, set exposure
time for approximately 1000 ms (or set appropriately for the experiment).
In the Setup Image tab, ensure gain is set to the level at which the
measurement is to performed and that 1 x 1 Binning and Full Area is
selected. Click the cursor on some pixels within the strongest signals to
Section 7. 3
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