 Phase contrast and differential interference contrast ( DIC ) microscopy are important tools in biology and medicine . Most animal cells and single @-@ celled organisms have very little color , and their intracellular organelles are almost totally invisible under simple bright field illumination . These structures can be made visible by staining the specimens , but staining procedures are time @-@ consuming and kill the cells . As seen in Figs . 24 and 25 , phase contrast and DIC microscopes allow unstained , living cells to be studied . DIC also has non @-@ biological applications , for example in the analysis of planar silicon semiconductor processing . 
