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Chapter 14 PI-MAX4: EM Family 211
14.2 Kinetics
Kinetics is a specialized imaging mode in which a small region of a CCD’s sensor area
(typically referred to as a
window) is exposed to incoming light while the balance of the
sensor area is temporarily masked to prevent exposure. This masked area is then used to
temporarily store previously captured images/data before they are moved to horizontal shift
registers/memory.
Images are able to be captured with s resolution by shifting each exposure under the
masked region before they are transferred to memory. Since there is no overhead of readout
time between each exposure, faster time resolution is achieved. At the end of a series of
Exposure-Shift cycles, the entire frame is transferred to host memory at a slower transfer
rate which does not negatively affect the time resolution.
14.2.1 Masking
NOTE:
The size of the window/mask is adjustable depending upon the
requirements of the specific application. Once the size of the
window has been determined, its height, in number of rows to
be exposed, is specified with the
Kinetics Window Height
field. See Figure 14-8.
Figure 14-8: Configuring Readout Mode
In kinetics mode, an additional section of the CCD sensor area must be optically masked in
order to minimize the cross-talk between subframes. Typically, in imaging applications, this
is accomplished by placing a “knife edge” or an optical mask in the collimated beam path.
Whereas, in spectroscopy, this is best achieved by limiting the height of the entrance slit of
the spectrograph. In most of the applications, the ability to mask as few rows as possible
sets the ultimate limit on the temporal resolution.
For best results, it is recommended that the size (in rows) of the masked area be a whole
multiple of the size (in rows) of the Sensor Window. By sizing the mask to be an integer
sub-multiple of the window (or as close to a whole number as possible,) the number of
“empty” rows is minimized, thus maximizing the amount of valid data that have been
collected.
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