Phase-contrast microscope

When it is diffracted, light slightly alters its phase so that different objects in a cell appear to take on color even though they are colorless ordinarily. Making use of such diffraction allows objects within the cell to be made out clearly and easily without killing the cell by adding a dye. A microscope using this techniques was constructed.
 Frits Zernike Netherlands 1938 Phase-contrast microscope

When it is diffracted, light slightly alters its phase so that different objects in a cell appear to take on color even though they are colorless ordinarily. Making use of such diffraction allows objects within the cell to be made out clearly and easily without killing the cell by adding a dye. A microscope using this techniques was constructed.