Differential interference contrast (DIC) converts gradients in specimen optical path length into amplitude differences that can be visualized as improved contrast in the resulting image. The specimen optical path difference is determined by the product of the refractive index difference (between the specimen and its surrounding medium) and the geometrical distance (thickness) traversed by a light beam between two points on the optical path. Images produced in DIC microscopy have a distinctive shadow-cast appearance, as if they were illuminated from a highly oblique light source originating from a single azimuth.
Nomarski differential interference-contrast microscopy. ZEISS Information 70: 114-120 (1968). The first article in a four-part series outlining the basic theory and practice of differential interference contrast. Published by Carl Zeiss in the late 1960s and early 1970s, these articles remain perhaps the best source of information about the technique. This article is an introduction to the theory of DIC microscopy.
Nomarski differential interference-contrast microscopy. II. Formation of the interference image. ZEISS Information 71: 12-16 (1969). Review of the wavefront field in differential interference contrast describing Wollaston prism action, interference background, orthogonal symmetry, image formation, and fundamental principles surrounding interpretation of the DIC image.
Nomarski differential interference-contrast microscopy. III. Comparison with phase contrast. ZEISS Information 76: 69-76 (1971). A discussion of the microscope configuration for phase contrast and DIC with emphasis on similarities and differences between the complementary techniques. Included are specimen thickness, depth of field, birefringence, and refractive index.
Nomarski differential interference-contrast microscopy. IV. Applications. ZEISS Information 77/78: 22-26 (1971). The final paper in the Carl Zeiss DIC series addresses various applications of DIC microscopy in the biological and material sciences. Among the topics mentioned are cytology, botany, histology, hematology, neurology, metallography, crystallography, mineralogy, and semiconductor applications.
The Zeiss-Nomarski differential interference equipment for transmitted-light microscopy. Zeitschrift für Wissenschaftliche Mikroskopie und Mikroskopische Technik 69: 193-221 (1969). Georges Nomarski and associates address the basic fundamentals of differential interference contrast. The authors discuss the wavefront field, shear, contrast, resolution, optical sectioning, amplitude contrast, and provide suggestions.
Nomarski's DIC microscopy: A review. Proceedings of SPIE 1846: 10-25 (1994). An excellent review by one of the foremost microscopists of the 20th Century. Professor Pluta reviews the basic principles of interference and the DIC wavefront field, covering shear, retardation, the extinction factor, and reflected ight DIC. Also described are the quantitative aspects of DIC imaging.
Principles and applications of differential interference contrast light microscopy. Microscopy and Analysis 20: S9-S11 (2006). A recently published discussion of DIC, highlighting the origins and advantages of the methodology along with a simplified explanation of how the technique is executed in practice. Discussed are the condenser, objectives, prisms, polarizers, microscope configuration, and image analysis.
The Sénarmont compensator: An early application of the geometric phase. Journal of Modern Optics 40: 2061-2064 (1993). A review of de Sénarmont compensators and their appliation to alterations of the wavefront field in DIC microscopy. This short review article is recommended reading for anyone who is conducting investigations with de Sénarmont DIC.
Light Microscopy: Contrast by interference. Nature Milestones, Milestone 8: (2009). This brief review focuses on the history of DIC microscopy and provides an excellent set of early references that founded the technique. Also included in the article is a drawing of the DIC microscope optical train and a section highlighting some of the most recent reviews on the topic.
High-resolution video-enhanced differential interference contrast (VE-DIC) light microscopy. Methods in Cell Biology 81: 335-364 (2007). Drs. Salmon and Tran explain how DIC is used to enhance video microscopy investigations. Discussed are the major features of the VE-DIC image, microscope design, digital and analog contrast enhancement, components, and bias retardation.