Patent ID: 6081335
Filing Date: 2000-06-27
Classification: G01B,G03F

Abstract:
A phase difference measuring method comprising steps for:generating ultraviolet light;branching said ultraviolet light into a first portion of radiant flux and a second portion of radiant flux;passing said first portion of radiant flux along a sample optical path through an object to be measured so as to produce a phase shift in the first portion of radiant flux;passing said second portion of radiant flux along a reference optical path;recombining said first portion of radiant flux that has passed along said sample optical path and said second portion of radiant flux that has passed along said reference optical path, so as to produce interference fringes due to a phase difference between the first and second radiant flux portions;generating a flux of visible light and combining the generated visible light flux with said ultraviolet light such that the optical axis of said visible light coincides with the optical axes of said recombined radiant flux and at least a portion of said sample optical path so as to pass through the object to be measured; andcalculating the phase difference between said two portions of radiant flux caused by said object to be measured based on spacing and light intensity of interference fringes that occur in said recombined radiant flux.