SEM FTW: Meryl lives again
Here is a 2mm stainless steel screw. It’s sitting on a standard, non-shrunken quarter for scale.
Here it is under Meryl’s beam at the lowest possible magnification.
Those threads are barely visible to the naked eye, but even at low magnification the stainless shows signs of galling.
At this magnification, the tip of the thread looks a bit like lumpy clay.
Can we get closer? Of course.
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:
Here is the same shell at low magnification:
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.
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!