Differential Interference Contrast (DIC) Microscopy
An excellent mechanism for rendering contrast in transparent specimens, differential interference contrast (DIC) microscopy is a beam-shearing interference system in which the reference beam is sheared by a minuscule amount, generally somewhat less than the diameter of an Airy disk. The technique produces a monochromatic shadow-cast image that effectively displays the gradient of optical paths for both high and low spatial frequencies present in the specimen. Those regions of the specimen where the optical paths increase along a reference direction appear brighter (or darker), while regions where the path differences decrease appear in reverse contrast. As the gradient of optical path difference grows steeper, image contrast is dramatically increased.
Digital Image Galleries
- Phase Contrast and DIC Comparison Image Gallery
Phase contrast and differential interference contrast (DIC) should be considered as complementary techniques that can employed together to fully investigate specimen optical properties, dynamics, and morphology. In many cases, each technique will reveal specific details about a particular specimen that is not apparent from observing images captured by other methods. The wide variety of images presented in this gallery are derived from both thick and thin transparent specimens, as well as specimens that have inherent contrast originating from synthetic dyes (stains) or natural pigments.
Digital Video Galleries
- Live Cell Imaging: Cell Motility
In multicellular tissues, such as those found in animals and humans, individual cells employ a variety of locomotion mechanisms to maneuver through spaces in the extracellular matrix and over the surfaces of other cells. Examples are the rapid movement of cells in developing embryos, organ-to-organ spreading of malignant cancer cells, and the migration of neural axons to synaptic targets. Unlike single-celled swimming organisms, crawling cells in culture do not possess cilia or flagella, but tend to move by coordinated projection of the cytoplasm in repeating cycles of extension and retraction that deform the entire cell. The digital videos presented in this gallery investigate animal cell motility patterns in a wide variety of morphologically different specimens using differential interference contrast microscopy.
Selected Literature References