Teledyne ProEM Series, System Manual

Page: 75 / 162

Chapter 5 Operation 75
5.3.9 Cleaning
The basic cleaning function is implemented by clean cycles. These cycles start when
you turn the camera on and a clean pattern is programmed into the camera. Their
purpose is to remove charge that accumulates on the array while the camera not
acquiring data (i.e., exposing and reading out the array).
Figure 5-17 is a timing diagram
for an experiment set up to acquire four (4) images in Freerun {No Response} timing
mode. In this diagram clean cycles occur before the first exposure and after the last
readout period.
Figure 5-17: Timing Diagram: Clean Cycles
NOTE:
The start of the exposure is signaled by SCAN going high but
will not occur until the current clean cycle has finished.
The configuration of clean cycles is performed on the Hardware Setup
►
Cleans/Skips
tab {via the Sensor Cleaning pane accessed on the Sensor expander}. When you set up
the camera for the first time, default values are automatically inserted into these fields.
These will give the best results for most applications. Even so it is a good idea to know
what these entries mean with regard to cleaning.
Cleaning Parameters
• Number of Cleans {Number of Clean Cycles} value is usually set to one (1). These
are additional clean cycles that can be required after a start exposure signal is
received and the current clean cycle has finished. The maximum value for this
entry depends on the camera.
• Number of Strips per Clean {Clean Cycle Height} sets the number of rows that
will be shifted and discarded per clean cycle. While a large number such as the
number of rows in the array may result in the best cleaning of the array, the
trade off is that there may be a significant delay between the receipt of a start
exposure signal and the beginning of the actual exposure. This delay occurs
because the current clean cycle must be completed before a start exposure
signal received during the cycle will be implemented. Typically, the default
setting is much smaller and in time critical experiments, the setting should be 1
or 2.
Clean
Cycle
Clean
Cycle
First
Exposure
Data
Stored
Data
Stored
Data
Stored
Data
Stored
Frame
Readout
Exposure
Last
Exposure
4
4
11-
01
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