SEM FTW: Meryl lives again

Happy Holidays!

Here is a 2mm stainless steel screw. It’s sitting on a standard, non-shrunken quarter for scale.

[This screw is just 2mm across, and is about as long as the LIBERTY on a quarter.

Here it is under Meryl’s beam at the lowest possible magnification.

[2mm screw at 35x. The bar scale at the bottom shows a reference line 0.5 mm long.

Those threads are barely visible to the naked eye, but even at low magnification the stainless shows signs of galling.

Let’s enhance.

[The tip of each thread is just over .06mm, but the edges have obvious surface variation.

At this magnification, the tip of the thread looks a bit like lumpy clay.

Can we get closer? Of course.

[At 1100x, a single thread on this tiny screw looks like a vast chasm.

Steel is a decent electrical conductor, so it’s relatively easy to image. Insulators (like most organic matter) are a lot tougher to shoot without special processing (such as sputter coating).

Here is a seashell:

[I bet this little creature never expected to be shot with an electron beam. That's life, I guess.

Here is the same shell at low magnification:

[At low magnification, the shell resembles a diabolical, [Giger-esque][12] landscape.

See the jets of “water” shooting off of the spikes to the left? That’s not photoshop, that’s physics.

As the electron beam scans the surface, the shell (being a poor conductor) accumulates charge. Over time the shell becomes more negatively charged. Like charges repel, so the electron beam is deflected.

The field in the shell will be strongest in the places with the strongest curvature (the tips of those spines). Since we’re using the beam to make the image itself, that’s exactly where the image will be the most distorted.

[Apparently this shell has the ability to warp spacetime. Maybe I'd better back off...

At higher magnification the problem only becomes worse.

I’m glad Meryl is finally taking decent (if not quite breathtaking) photos. If you could look at whatever you wanted under an SEM, what would it be?

Next project: a DIY sputter coater!

More SEM photos

SEM FTW: Meryl lives again
Posted on
December 24, 2014
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