Paper Title
INTRODUCTION OF A POLARIZATION CAMERA INTO A CIRCUMFERENTIAL SHEARING INTERFEROMETER FOR PHASE DIFFERENCE MEASUREMENT IN SNAPSHOT

Abstract
When measuring the shape of a surface, the difference between the measured surface and a reference surface is measured. Conventionally, by using a reference surface with high flatness, the shape deviation of the reference surface is set to zero and the shape of the measured surface is calculated. However, as machining accuracy has improved and the demand for measurement accuracy of the measurement target surface has increased, the shape deviation of the reference surface can no longer be ignored. Therefore, there is research into shearing interferometers that measure differences within the measurement target surface, thereby eliminating the need for a reference surface. This study reports on a circumferential shearing interferometer that uses a Dove prism to generate shear quantities in the circumferential direction, which is a problem in interferometry where light is split into two optical paths and the light intensity from the two paths cannot be the same. The phase shift method is generally applied to this problem. The phase-shift method requires the physical movement of the measurement object and multiple measurements. During multiple measurements, the measurement object and environment must be kept identical. For this reason, a polarization camera has been introduced to the phase-shift method to perform interference fringe analysis in a snapshot measurement. This study describes a method for analyzing the polarization state and extracting a phase image from the polarization image obtained by a polarization camera. Keywords - Circumferential shearing interferometer, Dove prism, Polarization camera, Surface measurement