Here you can discuss different microscopic techniques and illumination methods, such as Brightfield, Darkfield, Phase Contrast, DIC, Oblique illumination, etc.
If you get lost in the gazillion illumination techniques and why they do what they do, I suggest this good course on abbe optics: https://www.chalmers.se/sv/centrum/fysi ... bar/o1.pdf
knowledge about ray optics and interference required.