I was very excited to come across this post on modifying the foldscope with polarizing filters:

https://microcosmos.foldscope.com/2015/02/05/experiments-with-cross-polarization-and-fibers/

Since I work in a science centre, there is plenty of polarizing material hanging around but I decided that the easiest thing to do was to punch the lenses out of some old 3D glasses. Then I placed one lens between the LED light module and the foldscope body and the other lens between my phone camera and the foldscope (held in place by the magnets).

I tried to image some dog hair (as suggested by the original post) but my dog’s hair was uninteresting. However, I did have some polar bear hair samples at my desk and here’s what I saw:

I got some mineral samples from my co-worker and I plan to try to image those with the cross-polarization technique. Hopefully, I’ll get some more beautiful images.