Dalsa Piranha 2 Series, Руководство пользователя

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79 Piranha 2 User’s Manual
03-032-00493-14 Teledyne DALSA
Appendix D
DC Offset De-rating Curve
As of Decem ber 2004, all Piranha 2 line scan cam eras have been m od ified . This
m od ification has cau sed :

The Charge Transfer Efficien cy (CTE) of the sen sor to be im p roved , an d

An increase in d ark cu rrent at the m inim u m line rate and m axim u m gain.
This increased d ark cu rrent is only an issu e w hen the cam era is u sing long integration
tim es, at the m axim u m gain setting, or at high am bient tem p eratu res. Op erating the
cam era at h igh tem p eratu res or at low line rates w ith m axim u m gain, im p acts the
camera’s ability to perform offset calibration. Figure 12 illustrates camera operating
cond ition s an d the associated lim its for op tim al offset calibration. The offset valu es
ind icated are the valu es obtained after issu ing the
cao 0 5
(calibrate analog offset)
com m and . The p lot sh ow s th e DC offset over tem p eratu re at m axim u m gain w ith the
op tim al offset calibration lim it being rep resented by the Lim it line. The area u nd er the
Lim it line show s the op erating cond ition s w here the cam era’s offset can be calibrated to
cam era sp ecifications; the area above the Lim it line show s the op erating cond itions w here
the cam era’s DC offset is greater than cam era sp ecifications. If you are op erating the
cam era in this range, you m ay w ant to red u ce the effect of the increased d ark cu rrent by:

Ad ju sting the calibration target valu e higher to enable offset com p en sation to w ork.
For exam p le,
cao 0 30
.

Ad d ing cooling to red u ce tem p eratu re. Refer to the Therm al Man agem ent section on
p age 43 for m ore inform ation.

Op erating the cam era at higher line rate an d averaging or d iscard ing the extra lines
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