Compact Orientation-Independent Differential Interference Contrast (OI-DIC) Microscope Designed for High Resolution and High Sensitivity Mapping of Optical Path and Optical Path Gradient

Conventional differential interference contrast (DIC) microscope shows the two-dimensional distribution of optical phase gradient encountered along the shear direction between two interfering beams. Therefore, the contrast of DIC images varies proportionally to the cosine of the angle made by the azimuth of the phase gradient and the direction of wavefront shear. The image contrast also depends on the initial phase difference (bias) between the interfering beams. It is therefore necessary to examine the unknown object at several azimuth orientations and mechanically adjust bias of the DIC prism.