Ccd Handling Instructions; Electrostatic Discharge And The Ccd Sensor; Protecting Against Dust, Oil And Scratches - Teledyne HS-40-04k40 User Manual

112
CCD Handling
Instructions

Electrostatic Discharge and the CCD Sensor

Cam eras contain charge-cou pled d evice (CCD) im age sensors, w hich are m etal oxid e
sem icond u ctor (MOS) d evices and are su sceptible to d am age from electrostatic d ischarge
(ESD).
Electrostatic charge introd u ced to the sensor w ind ow su rface can ind u ce charge bu ild u p
on the u nd ersid e of the w ind ow that cannot be read ily d issipated by the d ry nitrogen gas
in the sensor package cavity. When charge bu ild u p occu rs, su rface -gated photod iod es
(SGPDs) m ay exhibit higher im age lag. Som e SGPD sensors, su ch as the IL-P4 and the IT-
P4 u sed in the Piranha2 cam eras, m ay also exhibit a highly non -u niform response w hen
affected by charge bu ild u p, w ith som e pixels d isplaying a m u ch higher response w hen
the sensor is exposed to u niform illu m ination. The charge norm ally d issipates w ithin 24
hou rs and the sensor retu rns to norm al operation.
! WARNING:
an erroneous calibration, ensure that you perform flat-field correction only after a charge
buildup has dissipated over 24 hours.

Protecting Against Dust, Oil and Scratches

The CCD w ind ow is part of the optical path and shou ld be hand led like other optical
com ponents, w ith extrem e care.
Du st can obscu re pixels, prod u cing d ark patches on the sensor response. Du st is m ost
visible w hen the illu m ination is collim ated . The d ark patches shift position as the angle of
illu m ination changes. Du st is norm ally not visible w hen the sensor is positioned at the
exit port of an integrating sphere, 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 pressed air
blow er, u nless the d u st particles are being held by an electrostatic charge, 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
barehand ed w ill leave oily resid u es. Using ru bber fingercots and ru bber gloves can
prevent oil contam ination. H ow ever, the friction betw een the ru bber and the w ind ow
m ay prod u ce electrostatic charge that m ay d am age the sen sor. To avoid ESD d am age and
03-032-20013-04
Charge buildup will affect the camera's flat-field correction calibration. To avoid
Piranha HS-xx RoHS User Manual
Appendix E
Teledyne DALSA