(a) The full FOV of the lens-free polarized image is 20.5 mm2 , approximately 2 orders of magnitude larger than the FOV of a typical 40×microscope objective lens (see yellow dashed circle). (b) A sub-region showing the lens-free polarized image. Crystals oriented along the 45° axis (see orientation guide in the bottom left) appear brighter than the background, and those along the 135° axis appear darker. (c–e) Lens-free grayscale differential image of 3 ROIs taken from (b). (f–h) Pseudo-colored images of (c–e) to approximate familiar CPLM images. (i–k) 40×0.75 numerical aperture CPLM images of the same regions as (f–h). White arrows: crystals that result in a weak signature have better contrast in the lens-free pseudo-color images (f,g) than the CPLM images (i,j). Yellow arrows: thick MSU crystals in the lens-free pseudo-color image (h) have hollow appearances, slightly different from the CPLM image (k).