Full-field radial-shearing differential interference contrast microscopy with Greek-ladder sieves

DIC-based microscopes use an interferometric optics system system in which the reference beam is sheared laterally by a small portion, usually somewhat smaller than the diameter of the Airy disk.It is usually smaller than the diameter of the Airy disk. The technique produces a monochromatic shadow image showing the gradient of the light path in the displayed specimen. Those areas of the specimen where the light path increases along the reference direction have areas that appear brighter (or darker), while areas where the path difference decreases appear in opposite contrast at the opposite contrast. As the gradient of the light path gets larger, the image contrast increases accordingly. Extensive mathematical derivations and simulations have been performed, and relevant experiments have been conducted to support the results.