If you are into ‘epi’ you may want to see the latest PUMA microscope video which is all about epi-illumination and shows detailed examples in epi-fluorescence and reflected light microscopy of a silicon chip die upto the ‘limit’ of standard light microscopy with oil immersion. See:
YouTube: Epi-Illumination - YouTube
and for more info on the open source PUMA DIY 3D printed microscope see:
GitHub: GitHub - TadPath/PUMA: 3D Printed Microscope