ORIUS ™ 833 User’s Guide Series Rev 3 4-2
• Turn off the Peltier cooler if the microscope viewing chamber is to
remain at air pressure for a long period (more than 30 minutes to an
hour).
• Turn the Peltier cooler off if the room the TEM has a dew point above
10C when the TEM is vented.
4.1.2 Scintillator maintenance and precautions
• Minimize exposing the scintillator to the electron beam when the
camera is not in use.
It is particularly important to protect the camera from being unnecessarily exposed to an intense unscattered
beam. As a general rule, if you avoid conditions which would saturate any part of the sensor area in less than 0.1
sec (about 10
2
cmnA at the sensor), the scintillator lifetime will probably exceed the lifetime of the rest of the
system. On the other hand, each time any CCD pixels are intensely saturated, the scintillator efficiency may be
permanently impaired for those pixels, resulting in a variation of the scintillator efficiency across the image
field. If you are not using the camera, keep the viewing screen down or retract the camera to protect the
scintillator from beam damage. Also, a retracted camera will not collect debris or abrasive particles that may fall
down from the TEM’s film-transport mechanism.
• Minimize exposing the scintillator/CCD to high beam intensity when
acquiring diffraction patterns.
There is no defined cutoff where the scintillator will be damaged. Rather, damage can result from prolonged
exposure of the scintillator to a very high beam intensity (above 15,000 counts in binned by 1 mode, exposure of
10ms). If you have no saturation with a short exposure, then there is no danger. You can then increase the
exposure time and still not harm the scintillator as it is the beam intensity on the scintillator that causes the
problem and not the accumulated signal in the CCD.
It is recommended to consider using the TEM beam stop to block the central spot when acquiring SAED
diffraction patterns that might be needed when recorded for long periods of time (in-situ).
If you think you have damaged the scintillator, take an unprocessed image of uniform illumination. If the spot
turns out dark, you have damaged the scintillator! If it is bright, spread out the beam and set the illumination so
you have about 10,000 counts/sec (in binned by 2 mode). Expose the scintillator for 3 min, and take another
picture. The bright area should be gone and the scintillator should operate normally.
• Warm the scintillator to 35 degrees periodically.
If you have a clean vacuum in the camera chamber area, warm the scintillator once or twice a month. But if you
have backstreaming from your diffusion pump, you will need to do it more frequently. The camera should only
be warmed for 15 hours or overnight, but not longer. If the camera is used sufficiently without warming, the
electron beam can harden the trapped oil making the scintillator difficult to clean.
Use the normal temperature control but instead of a target temperature of
10C give it a target of 35C.
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