Splendid image, polaroidia. Very nice!
So I spent a good half hour reading about phase contrast microscopy! Is it possible to modify a conventional microscope to phase contrast, for someone with decent optical/telescope/planetary imaging type skills?
It's possible to make the phase plates yourself (they're usually placed between the aperture diaphragm and the lens system of the condenser in a classic Zernike design, but placing them underneath the condenser's iris will work as well), but you still need the phase objectives.
Well actualy you need the objectives first, to measure the corresponding phase plates.
Phase objectives can be used for regular brightfield, but not the other way around.
Most brands of microscopes at the time had one or a few models for general use, and as an option for those one or a few phase plates that could slide into the condenser, f.e. providing phase contrast for the 40x objective, which was then a phase objective. That was the case f.e. for the, at the time very popular Olympus CH and CH2 stands but it was the case as well for some stands from far lesser known brands such as Kyowa (Japan) or Will/Hund (Germany) among many others.