Patent ID: 6404545
Filing Date: 2002-06-11
Classification: G02B

Abstract:
An optical apparatus comprising:a light source; an illumination optical system for leading light emitted from said light source to an object to be observed; an imaging optical system for magnifying and projecting an image of said object; an aperture member which is rotatable, disposed at an image plane of said imaging optical system or a conjugate plane thereof, and having an aperture section constructed with light-transmitting areas and light-blocking areas; a light-separating means for separating the light emitted from said light source into orthogonally polarized components; a light-combining means for combining the polarized components separated by said light-separating means, disposed in said imaging optical system; a polarized-light extracting means for deriving only a particular polarized component, interposed between said light-combining means and the image plane of said imaging optical system; an image sensor for picking up a magnified image of said object projected on the image plane of said imaging optical system; an image processor for storing an image obtained by said image sensor and using the image to perform a calculation; and a phase changer for changing a phase difference between the orthogonally polarized components, interposed between said light source and said light-separating means or between said light-combining means and said image sensor, wherein the light-transmitting areas and the light-blocking areas of said aperture member have boundaries formed in the range from a vicinity of a center of rotation of said aperture member to a vicinity of a periphery thereof so that a differential image is formed by performing a differential calculation with respect to respective corresponding pixels from at least two differential interference contrast images in which amounts of phase differences between respective two polarized components are substantially equal, but have different signs.