THORLABS WFS Series, Руководство по эксплуатации, Страница: 123 / 157

© 2007-2012 Thorlabs GmbH
120 WFS Series
5.3 Hot Pixel
Every digital camera can have a few ‚hot pixels‘ which are defective pixels showing
an intensity that is not proportional to the amount of absorbed light. Often, such pixels
appear brighter than ambient pixels, in rare cases also darker. Its appearance
depends strongly on exposure time and ambient temperature.
All cameras used for the Thorlabs series Wavefront Sensors have a hot pixel
correction already included which reduces such effects to a minimum.
Due to a long lifetime and temperature cycles the WFS cameras may show new hot
pixels which didn’t appear during factory calibration. Although such single pixel
defects do not degrade the WFS accuracy noticeably, functions like the automatic
exposure control may be influenced.
New hot pixel, visible in Lineview panel at horizontal position 200
In case a new, stable and strong hot pixel (more than 50 digits intensity deviation to
ambient pixels) becomes visible whether in panels ‘Lineview’ or ‘Spot Field’, you
may send your WFS instrument back to Thorlabs in order to repeat the hot pixel
correction.
Please contact your local Thorlabs office for return instructions.
The CMOS camera used for the WFS10 series instruments is much faster but
shows a higher noise level and less image uniformity. In addition, there are sporadic
hot pixels appearing rarely at a random image position. Such single pixel defects
are visible only momentarily within a single camera frame and do not lead to a
violation of the instrument’s specification.
The appearance of such sporadic hot pixels cannot be corrected and is no reason
for return the instrument.
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