Draft: Additional illumination components for Dark Field, Cross Polarized Microscopy, Modular Condenser

Described here: https://openflexure.discourse.group/t/experimenting-with-dark-field-and-polarized-microscopy-with-modularized-condenser-no-led-grid/1249

Below is an extract from the post, for description of the PR:

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. 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.