A nanometric displacement measurement method using the detection of fringe peak movement

Abstract

This paper proposes a novel method for measuring nanometric displacement by detecting fringe movement of interferograms which is linearly proportional to the displacement of an object. Interferometers have been used for precision measurement of displacement, but they have such error sources as unequal gain of detectors, imbalance of beams and lack of quadrature. These error sources degrade the accuracy of the interferometer. However, the fringe movement of interferograms has little relation to these error sources. In order to investigate the performance of the proposed method, analyses and simulations of speckle noise, Gaussian noise and wavefront distortion were executed. Results of the simulations show that the proposed method is robust against these errors. Experiments were performed to verify this method.