Differential Interference Contrast

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.
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Differential Interference Contrast

Brief Overview of DIC Microscopy

In the mid-1950s, a French optics theoretician named Georges Nomarski modified the Wollaston prism used for detecting optical gradients in specimens and converting them into intensity differences.

Fundamental Concepts in DIC Microscopy

Through a mechanism different from phase contrast, differential interference contrast converts specimen optical path gradients into amplitude differences that can be visualized as improved contrast in the resulting image.

DIC Microscope Configuration and Alignment

DIC components can be installed on virtually any brightfield transmitted, reflected, or inverted microscope, provided the instrument is able to accept polarizing filters and the specially designed condenser and objective prisms.

Comparison of Phase Contrast and DIC Microscopy

The most fundamental distinction between differential interference contrast and phase contrast microscopy is the optical basis upon which images are formed.

Fluorescence and DIC Combination Microscopy

Fluorescence microscopy can be combined with contrast enhancing techniques, such as differential interference contrast (DIC) and phase contrast illumination, to minimize the effects of photobleaching.

Differential Interference Contrast Articles

Thin unstained, transparent specimens are excellent candidates for imaging with classical differential interference (DIC) microscopy techniques over a relatively narrow range (plus or minus one-quarter wavelength) of bias retardation. The digital images presented in this gallery represent a wide spectrum of specimens, which vary from unstained cells, tissues, and whole organisms to both lightly and heavily stained thin and thick sections. In addition, several specimens exhibiting birefringent character are included to demonstrate the kaleidoscopic display of color that arises when anisotropic substances are imaged with this technique.

Contributing Authors

Douglas B. Murphy - Department of Cell Biology and Anatomy and Microscope Facility, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 107 WBSB, Baltimore, Maryland 21205.
Edward D. Salmon - Department of Cell Biology, The University of North Carolina, Chapel Hill, North Carolina 27599.
Kenneth R. Spring - Scientific Consultant, Lusby, Maryland, 20657.
Mortimer Abramowitz - Olympus America, Inc., Two Corporate Center Drive., Melville, New York, 11747.
Maksymilian Pluta - Physical Optics Department, Institute of Applied Optics, 18 Kamionkowska Street, Warsaw, Poland, 03-805.
Matthew Parry-Hill, Robert T. Sutter and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.