Comparing plain vs crossed polarisation for various samples – all x3.5 magnification as currently this is only objective I have for this microscope – uses special clamp mechanism so my other objectives won’t fit.
For more information on the LOMO Polam P-113 Polarising Microscope, see a wide range of posts at: http://roslistonastronomy.uk/category/microscopy/equipment-for-microscopy/lomo-polam-p-113-microscope
Permian-floodplain-deposit-Robledo-New-Mexico-LOMO-Polam-P113-Crossed-Polars-120518: Excellent birefringement is shown here, and this can be seen varying between the images as polarised filter rotated (below).
Laminated-mudstone-LOMO-Polam-x3-5-plane-polar-120518: Some birefringence evident where crystals form in both images, more so in bottom as the two polarised filters approach 90 degrees orientation to each other (below).
Fossilised-palm-tree-LOMO-Polam-x3-5-plain-polar-120518: Even here some crystal deposition is evident, as shown by coloured areas of birefringence, more evident in second image where polars are crossed (below).