Nanometer Displacement Measurement by the Speckle Interferometry using an Inequality Distance Phase Shift Method

Abstract

We measured the displacement of the rough surface object with speckle interferometry. The interference fringes are evaluated with four sensors. These change with the displacement of the object sinusoidally. Each phase differences of these are constant, but these are not always equal distance. Therefore these are analyzed by inequality distance phase shift method. As a result, the displacement was measured for the sensitivity of nanometer.