3-dimensional micro-structure inspection by phase-shifting digital holography

Abstract

We have developed a holographic microscope for the inspection of the 3-dimensional structure of opaque objects. It is based on the phase-shifting digital holography. Digital holography has several characteristics such as free focusing, flexible magnification, and variable viewing angle that can not be shared by other methods. Phase-shifting technique is employed to contour the surface of an opaque micro-object quantitatively. A Michelson-type interferometer is configured as a part of the microscope in such a way that high numerical aperture and compactness can be obtained. We present several results of micro-object measurements and visualization of 3-dimensional structure.