This link is to Series 5 Ep 1 of Fake or Fortune investigating the authenticity of a portrait by the young (16?) Lucian Freud.
Interesting viewing throughout, but I want to draw your attention to 16min and 44min in to the video.
At 16 minutes a USB Microscope is employed to isolate a hair trapped in the paint for DNA analysis.
At 44 minutes the same is used to determine the brushstroke characteristics and paint application sequence to determine whether the painting was wholly done by Freud or in part by another artist.
This is very useful technology (for nerds like me) to examine whole screen images and capture pdf images of pretty small things ... stamps. coins, insects, flowers. What about creating a random background for my next painting ...
This is a pastel chalk line over a ColourFix ground. The width of this view is about 3 or 4 millimeters or 1/4 inch.
I was able to buy a 5 megapixel USB microscope for AU$190.
Here is a short demo video
Looks like a useful piece of kit.