What is DIC? Why is it used in cell microscopy?
FIgure 1: Volvox, a green algae living in fresh water ponds viewed by different kinds of microscope illumination a) bright-field b) dark-field c) phase contrast d) differential Interference contrast e) Rheinberg lighting f) fluorescence microscopy with green excitation.
Differential interference contrast microscopy (DIC) requires plane-polarized light and additional light-shearing (Nomarski) prisms to exaggerate minute differences in specimen thickness gradients and refractive index. Lipid bilayers, for example, produce excellent contrast in DIC because of the difference in refractive index between aqueous and lipid phases of the cell. In addition, cell boundaries in relatively flat adherent mammalian and plant cells, including the plasma membrane, nucleus, vacuoles, mitochondria, and stress fibers, which usually generate significant gradients, are readily imaged with DIC. In plant tissues, the birefringent cell wall reduces contrast in DIC to a limited degree, but a properly aligned system should permit visualization of nuclear and vacuolar membranes, some mitochondria, chloroplasts, and condensed chromosomes in epidermal cells. Differential interference contrast is an important technique for imaging thick plant and animal tissues because, in addition to the increased contrast, DIC exhibits decreased depth of field at wide apertures, creating a thin optical section of the thick specimen. This effect is also advantageous for imaging adherent cells to minimize blur arising from floating debris in the culture medium.
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http://zeiss-campus.magnet.fsu.edu/articles/basics/contrast.html
Berdan, 2021: Differential Interference Contrast Microscopy and other methods of producing contrast. The Canadian Nature Photographer: https://canadiannaturephotographer.com/diffential_interference_microscopy.html
Sanderson, 2007: Setting up the Differential Interference Contrast (DIC) microscope
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