79 Piranha 2 User’s Manual
03-032-00493-14 Teledyne DALSA
Appendix D
DC Offset De-rating Curve
As of December 2004, all Piranha 2 line scan cameras have been modified. This
modification has caused:
The Charge Transfer Efficiency (CTE) of the sensor to be improved, and
An increase in dark current at the minimum line rate and maximum gain.
This increased dark current is only an issue when the camera is using long integration
times, at the maximum gain setting, or at high ambient temperatures. Operating the
camera at high temperatures or at low line rates with maximum gain, impacts the
cam era’s ability to perform offset calibration. Figure 12 illustrates camera operating
conditions and the associated limits for optimal offset calibration. The offset values
indicated are the values obtained after issuing the cao 0 5 (calibrate analog offset)
command. The plot shows the DC offset over temperature at maximum gain with the
optimal offset calibration limit being represented by the Limit line. The area under the
Limit line shows the operating conditions where the camera’s offset can be calibrated to
camera specifications; the area above the Limit line shows the operating conditions where
the camera’s DC offset is greater than camera specifications. If you are operating the
camera in this range, you may want to reduce the effect of the increased dark current by:
Adjusting the calibration target value higher to enable offset compensation to work.
For example, cao 0 30.
Adding cooling to reduce temperature. Refer to the Thermal Management section on
page 43 for more information.
Operating the camera at higher line rate and averaging or discarding the extra lines
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