Is the openflexure designed so that the slides are upside down (coverslip downward)? If yes how do you keep the coverslip from falling? Some samples that im interested in are blood, hair, onion skin (transmission) and fibres, microchips (using reflection optics).
I was just about to post this same question today. For prepared slides, it’s not a problem. For slides made locally, it’s not straightforward. I’m wondering if a 3D printed part might be useful in this case (not sure of what material though). You could create a slide holder with a groove in it to hold the cover slip and slide, in such a way that when you flip it the slide isn’t pressing any weight against the cover slip. I feel like it would be difficult to keep clean. Here’s a picture I made in blender demonstrating what I mean. You may have to zoom in to see the grooves on the holder.
Not sure if there’s enough precision in 3D printing for this though.
But I can’t imagine someone hasn’t come across this issue before. I’m curious what the answer is myself.
Clear nail polish 
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You can just put a think layer around the outside of the coverslip once it is in place
What about for live cells?
There are a few options.
The first is to use the Upright version of the OpenFlexure Microscope, which is ideal if you are looking at slides with coverslips. If you have already built the standard inverted microsope, then you can use the body, motors, electronics and optics module that you have. You will need to print the separate_z_axis, the mount/spacer for that and another foot and large gear, plus the upright illumination module. You transfer the optics module to the new z-axis stage, above the main stage, but you will need a longer camera cable. The upright illuminaton module uses all the same parts as the standard module, but it helps if you have another condenser lens as you can only get them out of the mounting a few times before the flange on the lens breaks too much. You will also need a few more M3 nuts and screws and the viton band.
The second option for up to 40x is simple but more costly. There do exist long working distance 20x and 40x objectives that are designed to work through 1.1mm of glass. The ones I know of are infinity corrected, so need the rms_infinityversion of the optics module. You don’t want a ‘metallurgical’ long working distance objective, they may have space to physicallt fit 1mm of glass but that will give aberrations.
Finally, for live cell cultures there are small petri dishes avaliable which have a section of the base that is as thin as a coverslip, so that you can view with a standard lens in the inverted configuration.
I’m building the delta stage reflection + grid illumination. so I guess i’ll have to mount the optics on top and somehow mount the grid on the bottom? I will probably build the standard version first then try to tinker with it.
Why do you use the Delta Stage version particularly?
I think that mounting the grid illuminaton below may be difficult. There is not a lot of space, although with a bit of customisation there can be more by taking out the optics fitting mount. How far do you need the grid to be away from the sample?
There’s no particular reason for choosing the delta stage. Mainly because it has reflection and grid illumination(however i kinda realised afterwards that that’s possible with v7), I also sorta like the idea of only moving the slide and it’s visually more appealing for me. However, I do think that an upright delta stage is slightly better than normal upright as the top will be lighter (less strain and less likely to get tipped over. I’m still waiting for my components to arrive so i don’t currently know how far the grid has to be.
I came across this Microscope slide Cobb - coverslip holder by pattarini - Thingiverse where only a coverslip is used. Maybe it’s a viable solution?
