Why was an electron microscope necessary? Surely at this scale a conventional light microscope would have done the job, wouldn't have needed all these workarounds, and could have recorded live footage of a needle actually playing a record?
The aperture size in the SEM is much smaller than that used in a camera or microscope, leading to much higher depth of field for a given geometry and working distance. A camera might be f/16, while this SEM is effectively f/200
The brightness of objects in the image is partially influenced by the material properties and local geometry, so an exposed protrusion or edge will tend to be very bright -- something that doesn't happen with macro photography.
Hey, it's fun to play with scanning electron microscopes.