||Description of the Problem
See Note 1 below
||Pixels with this defect will indicate being illuminated even when no signal is present. These are the most troublesome when attempting to make accurate peak fluence and peak fluence location measurements because they represent a false signal. Most other measurements are not adversely affected by this type of defect. This type of defect is screened for during our regular camera inspection process. All pixels that exceed a set limit are corrected, if possible, before the camera ships. See Note 1 below. Our QA department will often reject cameras if the pixel can not be corrected and it exceeds our acceptance criteria.
- Ultracal/baseline correction will subtract out the defective pixel.
- Reposition the camera to remove the defective pixel from the measurement region and employ a manual aperture to isolate the pixel from the area of interest.
- Return the camera to OSL to have the bad pixel corrected and the camera re-certified.
||This is an intermittent version of the Bright Pixel defect. These often appear as the camera warms up. May disappear if the camera is run in cooler environments. Usually predicts a pixel that will soon be a permanently bright pixel defect.
These are the hardest to detect and as such may get past our camera inspection process.
|Same as above.
If returned to OSL to be corrected please send a full frame data file showing the pixel as it is malfunctioning. This will aid in our ability to find and fix it.
||Dark pixels have low responses compared to the amount of illumination that they receive. Isolated instances of these types of defects do not pose a serious beam analysis problem and they are generally not in need of correcting.
||This type of defect will not significantly impact a beam measurement result unless the beam is very very small and the defect falls inside of the beam profile. Reposition the camera to remove the defective pixel from the measurement region.
||Dead pixels have no response at all and may output a raw pixel value of zero (0) counts. This type of defect is screened for during our regular camera inspection process. All pixels that exceed a set limit are corrected, if possible, before the camera ships.
||This type of pixel may create a warning message when performing Ultracal operations. Ignore the warning and proceed as in the Dark Pixel case described above.
||These dimmer than normal clusters involving about a dozen or fewer pixels are often caused by dust particles and can usually be removed by cleaning of the imager. Sometimes these can be very difficult to impossible to remove. In the latter case they are may be melted into imager
If this is the result of laser damage then imager replacement is the only solution.
|These usually do not cause serious measurement problems and can be treated with the Dark Pixel workaround described above. They can sometimes be dislodged with very gentle puffs of dry air. If you return a camera to be re-certified we have a few special methods for cleaning these, but success is not 100% guaranteed.
|Regions of non-uniform response
||When large areas of an imager yield reduced signal levels this usually indicates laser damage. Long term exposure to ultraviolet radiation or overexposure to high laser power or peak energies are common causes.
||This type of degradation is not repairable and either the camera or the camera imager must be replaced.