Re: SEM FAQ and/or links

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• In reply to: Gary G: "Re: SEM FAQ and/or links"
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Date: Tue, 08 Mar 2005 13:57:32 GMT

In article <vbgp21ta642cpl1ujoeosmnuvg7p85m2g1@4ax.com>,
 Gary G <see.signature@bottom> wrote:

> On Sun, 27 Feb 2005 14:33:34 -0600, Richard Owlett
> <rowlett@atlascomm.net> wrote:
>
> >I saw a thread on another group about scanning electron microscopes.
> >It raised "how is it implemented type questions?"
> >
> >A Google wasn't productive as I got back results results which were
> >aimed at "theory of operation" rather than "practice of operation" so to
> >speak. Or, at the other extreme, were engineering/purchase specs of one
> >manufacturer's components.
> >
> >Typical of the style of question I have in mind is:
> >"Mechanically, how is sample manipulated to scan various portions of it."
> >
> >I figured a FAQ or organized list of links would get me pointed in
> >productive directions. Unfortunately I do not have access to a academic
> >library to browse. [ I'm in *rural* SW Missouri ]
> >
> >Thank you
>
> The sample is either mechanically moved using the SEM stage or the
> beam scan area is electronically moved. Or, one can do both methods.
> The ability to move the specimen mechanically is determined by the set
> of features that are inherent to a specific stage design. e.g., x, y,
> z, r and t. Some may do just x & y while others may do x, y and r or
> combinations. The more sophisticated stages are 5 and 6 axis and are
> eucentric. These stages are motorized. There are multi-axis stages
> that are manually manipulated.
>
> Hope this answers your question.
>
>
> Gary Gaugler, Ph.D.
> Microtechnics, Inc.
> Granite Bay, CA 95746
> 916.791.8191
> gary@microtechnics dot com

OK, in English, there is a mechanism in the SEM which allows you to move
the specimen in three directions, up and down, back and forth, left and
right. The staging is also set up so you can rotate the specimen and to
change its angle with respect to the electron beam. The mechanical
motions allow you to move large samples into the region where the
electron beam is located. There is some ability to move the beam back
and forth and left to right electronically, but that is for very small
areas.

The specimen stages in the older SEMs were moved with geared mechanisms
which were operated by hand from the outside. The new SEMs have
electronic controls for servos which can move the specimen stage. They
may even be configured so that your unit can "remember" each location of
interest so that you can go back to it rapidly.

On the older SEMs, I got calluses on my fingers from having to rotate
the dials so much. The external dials were calibrated so you could more
or less find the same place. My samples often were large, like an inch
in diameter. So you really had to crank to get from one edge to the
other.

Al

• Previous message: Gordon Couger: "Re: Tube length"
• In reply to: Gary G: "Re: SEM FAQ and/or links"
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