ABSTRACT
In its simplest form, microscopy relies on the absorption of light to achieve contrast. However, biomembranes absorb little light, so they are almost invisible in amplitude contrast. The
invention of ingenious optical techniques such as phase contrast2 or differential interference contrast3 that convert minute phase changes of light into well-contrasted micrographs enabled visualization of membranes and paved the way to the observation of dynamic processes in living cells, such as cytoskeletal streaming, transport of organelles,4 or formation of adhesion complexes.5
