ORIUS ™ 833 User’s Guide Series Rev 3 4-4
The shortest time is 0.001 sec. Exposures over 5 minutes are unusual for
this camera under normal imaging conditions. Longer exposures might be
done for diffraction imaging
4. My images are noisy, what can I do?
Try increasing the exposure or current density of the beam or if possible try
frame summing if the specimen has no drift
5. My images are slowly deteriorating, what should I do?
Determine if the CCD is warming up. Check that the water lines are not
clogged. Check the water temperature of the chiller- should be
approximately 20-23 °C. Be sure to acquire a new gain-reference image.
6. The image is brighter (or darker) on the top than on the
bottom, what should I do?
Check that the CCD has been cooled for at least 5 minutes.
It could be a bad gain reference image. Retake another one.
7. When viewing, the image sometimes gets suddenly
bright/dark, what is happening?
Sudden changes in the contrast may be due to stray x-ray photons that
saturate some of the pixels. Also, Auto Survey will respond if a grid bar or
large piece of debris on the sample is seen. This will affect the histogram
and appearance in compensating for the large amount of black pixels seen.
8. How long is the lifetime of the CCD?
None of Gatan’s CCDs have failed due to old age so it is hard to answer.
So far, there are no known mechanisms for aging.
9. How often and for how long should the camera be warmed?
If you have a clean vacuum in the camera chamber area, between once or
twice a month is enough. But if you have backstreaming from your
diffusion pump, you will need to do it more frequently. The camera should
only be warmed for several hours or overnight, but not longer. A quick
way to see if oil is accumulating is to take a uniform illuminated image at
40 or 60 kV. At a lower accelerating voltage, you will have greater
diffraction contrast which makes viewing the contamination more readily.
10. The camera takes a long time to insert/retract, what should I
do?
Check your compressed-air pressure. It should be between 30-60
2
cmN .
11. I see a ghost image that won’t go away, what should I do?
It is possible that the dark or gain reference has a ghost image. Try clearing
and re-acquiring the reference images. You can remove the dark reference
image by choosing Remove dark references under the Camera menu.
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