Hyaluronic Acid dried on slide

I put a drop of a Hyaluronic acid solution on the slide.  I didn’t see anything with brightfield/polarizing microscopy.  I looked at it again 2 days after it had dried, with one polarizing filter, then both and finally with polarizing filters and a “frugal” compensator (the coverslide in our Foldscope kits).

Down feather with a polarizing filter

I took these pictures with my foldscope and used polarizers to do so.  The one with a pinkish background had both polarizing filters and a compensator device between them.