There are some images floating around the Internet that were supposedly taken with a microscope, built in the 1920s, that was supposed to achieve resolutions that would normally be ludicrous for an optical microscope, then or now, due to being smaller than the wavelength of light (and is caught up in a complicated conspiracy theory).
By the way, there seem to be strong indications in the surviving documents that it was actually an ultraviolet microscope as well as or instead of a visible-light microscope, so that might have some bearing on what's plausible in the way of resolution.
Not sure whether this question belongs here or at Physics.SE, but it seems like here might make more sense since the question is what these micro-organisms are.
There are about twelve or thirteen of these pictures floating around. Some of them, on investigation, turn out to be magnified only 5000x or so, which, from what I've seen, seems to be considered impressive for a light microscope but not unheard-of. These are some of the ones that I'm still puzzled by.
(Can put more details/refs of the microscope in the question if you like - wasn't sure whether you'd object to things being discussed on your site that are connected by association with a conspiracy theory :-D )
Question - I'm not a microbiologist, what do people here who are more used to microscope images think these images show, and at what magnification?
These three were published in a Smithsonian Institute annual report in 1944, pp. 240-242.
Caption - "Chlorophyl cells (algae)" - doesn't make sense. From my limited knowledge of these things, it looks like a diatom, which seem to be a very commonplace subject for microscopes. But one article I read implied that a trained biologist had been very impressed by this photo - maybe the writer had the wrong end of the stick. Not sure what sort of diatom it is, if it is one.
Supposedly, the head of a tetanus bacterium, showing the spore, which, according to my brief Internet research, is possibly about 5 micrometres wide - so the quoted magnification of 23,000 sounds about true, if it really is a tetanus bacterium.
Supposedly, a typhoid bacterium, which, according to my brief Internet research, is possibly about 1 micrometre wide by 3 long.
Included because it's not labelled and I'm not sure what it is. Diatoms? No reference for where this one originally came from. This copy from https://www.rife.de/images/calibrate1.jpg.