X-ray

Maybe not technically microscopy but close enough. These units are useful to see packages, HSMs, etc before making cuts.

CSAM might be a good alternative to x-ray imaging

DIY

Some people make DIY x-ray setups by using "lighthouse" vacuum tubes and using photographic films. Might be able to use an intensifier to make it digital. Could integrate x-ray blotches over time on a CCD? Not fast and small area but might be inexpensive / easy.

Micro Focus

Micro-50: nice smallish unit. Read chamber reported as 14" wide X 14" deep X 13" tall. Probably takes film. Also had on it "MAGNAFLUX X-ray Equipment"

Chip imaging

[1]

Claims 0.5 um resolution, could be used to non-destructively image some old chips

SLAC

[2]

[3]