Three-dimensional shape measurement beyond the diffraction limit of lens using speckle interferometry

摘要

Speckle interferometry is generally known as a method that measures the deformation on an object with rough surfaces. In this paper, a three-dimensional (3-D) shape-measurement method is proposed for superfine structures beyond the diffraction limit using the basic feature of speckle interferometry. Because the differential coefficient distribution of the shape of such an object can be detected by giving a known lateral shift to the measured object in speckle interferometry, the shape can be reconstructed by integrating the differential coefficient distribution. Based on experimental results obtained using diffraction gratings as measured objects, it is confirmed that the proposed method can measure 3-D shapes that are beyond the diffraction limit of the lens.