🚀 go-pugleaf

In article <1992Oct9.175017.1901@news2.cis.umn.edu>, Stuart McKernan <stuartm@epx.cis.umn.edu> writes:
|> The Gatan CCD cameras have a YAG scintillator which is coupled to the CCD 
|> through a fiber optic plate. More information may be found directly from
|> Gatan

a couple things to watch out for:

	- Gatan (as well as most suppliers) thins the YAG to decrease 
	  blooming, then coats it with gold to get back some amount of 
	  contrast.  Since the electrons are pounding into gold, x-rays
	  are produced that will, over time, yellow the fiber optic bundle
	  attached.  Also, the TEM should be shielded well enough, but 
	  (especially if you're on an upper floor), you might want to 
	  crank up the scope to its full useful voltage and run a geiger
	  counter around (if on an upper floor, check below the machine)
	  just in case.

	- also, since an optical _bundle_ of fibers is being used, an aliasing
	  effect will be produced (BTW, they couple the scintillator to the
	  CCD to increase quantum efficiency).  As I recall, Gatan post-
	  processes the data to get rid of the 'ringing' that would otherwise
	  be a problem.  As I vaguely recall, their method of deconvolving 
	  this wasn't too sound (IMHO), and you could lose an unspecified
	  amount of high-frequency information which, in our application,
	  wasn't something that we wanted to live with...

						kevin