[Sem] Last Night's Demo Notes
Chris Murphy
chrisnoisebridge at gmail.com
Thu May 26 21:56:56 UTC 2011
Last night, we fashioned a wooden camera mount for DSLRs that is
compaible with the SEM camera bellows system that was made last year.
Thanks for your help Alan.
After photographing a specimen, we decided to get seriously involved
in cleaning the electron gun cartridge and replacing the filament. The
image was wandering on screen and the emmision gauge was occaisionally
pegging beyond 300 which signaled an aging filament. Also, the image
has always been ghosting at resolutions higher than 2000x.
The SEM is presently inoperable because the electron gun cartridge was
not sufficiently clean to warrant returning it into the machine. We
ultrasonically cleaned it in water along with all of the spare
electron gun parts but that didn't seem to be enough to get off the
residue.
The next steps are to use a small diameter wooden stick in the drill
press and some metal polish to remove more dirt from the parts of the
electron gun cartridges.
It appears that the electron gun cartridge we had been using had so
much metalic debris that it had been shorting to ground periodically
(tested with an ohm meter). The filament was blackened unlike a new
pristine white filament. When we complete the cleaning we will do
another demo evening of the SEM to see if the image has improved.
We also dissasembled the vacuum tube era ultrasonic cleaner that Larry
kindly donated. We repaired it's fan and fuse and generally cleaned it
up. It works well now.
Thanks everyone!
Chris
Sent from my iPhone
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