Disclaimer: I am new to microscopy and optics etc. Just making all this as hobby cuz I am really interested (since I was a child). Made everything on a resin printer so might or might not work directly on FDM
Hey! So I finally made my openflexure microscope v7 (beta1) with high res optics (though cheap 40x objective). I then learned about other kinds of microscopy including dark field, polarizing, phase contrast etc, so curious and wanting to try them out, I dug a little deep as how to upgrade my current scope for these. I am starting with Dark field and Polarizing microscopy for now, and wanted to share my experiments and experiences with the forum.
Openflexure project provides an LED grid solution for dark field, but I couldn’t source the original LED grid, and didnt wanted to port the code for alternatives, so I decided to make modular versions of the condenser module, one in which the Lens gripper is seperate from the condenser body, and add a condenser diaphragm/annulus in between the space (or anything else for that matter). Afterall, for dark field, the light needs to be indirect, and many traditional solutions are similar to this. But the original condenser in Openflexure is only for 5mm LED or an LED board (which I dont have), which won’t give enough illumination for an anulus based design. So some designing and lots of failed prints later, I designed an 8mm compatible illumination system, with detachable Lens Gripper, and a 3d printed annulus to go in between.
I also tried adding a linear polarizer instead of the annulus, and another linear polarizer in the gap between the objective and the tube lens in the unmodified optics module. Rotating the gripper allows to tweak how much light passes. When at 90 degrees, no light can pass unless its ‘unpolarized’ by something in between (the sample), thus giving us polarized microscopy. Inspired by this video:
(240) Upgrading a Cheap Microscope Lets You See Rainbows! - Polarized Light Mod - YouTube (240) Upgrading a Cheap Microscope Lets You See Rainbows! - Polarized Light Mod - YouTube
The results I think are quite good (dark field) (1st is my blood clotted, 2nd is my hair):
The polarized light results looked similar at polarizers@90 (some random glass debris):
However at angles != 90, it made everything colorful, here is a sperm slide (not mine, pre-prepared off of amazon):
Couldn’t capture it at 90 degrees as the cells weren’t visible properly.
Infact, I am unable to test the polarized version with any of the cheap prepared ones properly (maybe the dye used or something); I guess the samples aren’t bifringent enough. And I cant prepare my own for it, as don’t have 0.17 cover slips, and plastic tape interferes with the polarization, causing everything to appear white.
I calibrated the scope with no lens gripper (and no lens/annulus/polarizer) attached, with just the 8mm LED shining on the objective, As there was no way of calibrating it with the proper setup, cuz ideally everything is black and the software tries to make things Not-black.
Here is my scope and the parts:
Not including the modified Lid and the LED holder, they are trivial. Also, made an 8mm version of the aperture and modified the cutout
Let me know if I am doing things right and suggestions and advice. And If someone wants, I can put the SCAD files in a fork or something too. I have taken care to not modify any core SCADs to alter existing standard parts, and have taken care with the code quality, so maybe if admins permit, I can put it in a separate branch and make a PR too?