April 26, 2012. This is a repeat of an earlier message about the TEM camera.
There are dust particles on the TEM camera element. This is impossible to prevent, but the software has been designed to “erase” the effects from images. This is accomplished by a calibration that I periodically perform. A separate calibration is carried out at 100, 200 and 300kV and stored in the Gatan folder. The calibration for 200kV and 300kV are nearly identical, but 100kV is much different. At 100kV images that have been calibrated at 200kV/300kV will display black spots on the images. At 200kV/300kV, images calibrated at 100kV will show white spots. You may recall that I wrote you some months ago after we created 3 files that reside on the PC desktop that update the calibration for the particular kV you are using. All that you need to do is dbl-click the correct file, named 100kV, 200kV or 300kV (clever filenames, right?). The prompts will tell you what to do and your image will have no white or black spots.
Let me know if you have questions.