Dalsa Piranha 2 Series, Руководство пользователя

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51 Piranha 2 User’s Manual
03-032-00493-14 Teledyne DALSA
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5
CCD Handling
Instructions
5.1 Electrostatic Discharge and the CCD Sensor
Cam eras contain charge-cou p led d evice (CCD) im age sen sors, w hich are m etal oxid e
sem icond u ctor (MOS) d evices and are su scep tible to d am a ge from electrostatic d ischarge
(ESD).
Electrostatic charge introd u ced to the sensor w in d ow su rface can in d u ce charge bu ild u p
on the u nd ersid e of the w ind ow that cannot be read ily d issip ated by the d ry nitrogen gas
in the sensor p ackage cavity. When charge bu ild u p occu rs, su rface-gated p h otod iod es
(SGPDs) m ay exhibit higher im age lag. Som e SGPD sen sors, su ch as the IL-P4 and the IT-
P4 u sed in the Piranh a 2 cam eras, m ay also exhibit a highly non -u niform resp on se w hen
affected by charge bu ild u p , w ith som e p ixels d isp laying a m u ch higher resp on se w hen
the sensor is exp osed to u niform illu m ination. The charge norm ally d issip ates w ithin 24
hou rs an d the sen sor retu rn s to norm al op eration.
WARNING:
Charge buildup will affect the camera’s flat-field correction calibration. To avoid an
erroneous calibration, ensure that you perform flat-field correction only after a charge buildup
has dissipated over 24 hours.
5.2 Protecting Against Dust, Oil and Scratches
The CCD w ind ow is p art of the op tical p ath and shou ld be han d led like other op tical
com p onents, w ith extrem e care.
Du st can obscu re p ixels, p rod u cing d ark p atches on the sensor resp onse. Du st is m ost
visible w hen the illu m ination is collim ated . The d ark p atches shift p osition as the angle of
illu m ination changes. Du st is norm ally not visible w hen the sensor is p ositioned at the
exit p ort of an integrating sp here, w here the illu m ination is d iffu se.
Du st can norm ally be rem oved by blow ing the w ind ow su rface u sing a com p ressed air
blow er, u nless the d u st p articles are being held by an electrostatic ch arge, in w hich case
either an ionized air blow er or w et cleaning is necessary.
Oil is u su ally introd u ced d u ring hand ling. Tou ching the su rface of the w ind ow
barehan d ed w ill leave oily resid u es. Using ru bber fingercots an d r u bber gloves can
p revent oil contam in ation. H ow ever, the friction betw een the ru bber and the w ind ow
m ay p rod u ce electrostatic ch arge that m ay d am age the sensor. To avoid ESD d am age and
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