Determination of surface structure profiles using a differential phase optical microscope

A method was developed for directly recovering the optical phase profile of a surface from measurements made with a differential phase optical microscope. A study was made of how the parameters of the differential phase optical microscope and experimental errors influenced the measurement accuracy and resolution of the microscope in the object plane. The refractive index profile of ion-exchange channel waveguides in glass and the surface profile in a Y coupler made by diffusing titanium into lithium niobate were recovered from the results of measurements with a differential phase optical microscope. A resolution of 0.5 μm was obtained in the object plane.