Mixed Error Compensation in a Heterodyne Interferometer Using the Iterated Dual-EKF Algorithm

Abstract

The heterodyne laser interferometer has been widely used in the field of precise measurements. The limited measurement accuracy of a heterodyne laser interferometer arises from the periodic nonlinearity caused by non-ideal laser sources and imperfect optical components. In this paper, the iterated dual-EKE algorithm is used to compensate for the error caused by nonlinearity and external noise. With the iterated dual-EKE algorithm, the weight filter estimates the parameter uncertainties in the state equation caused by nonlinearity errors and has a high convergence rate of weight values due to the iteration process. To verify the performance of the proposed compensation algorithm, we present experimental results obtained by using the iterated dual-EKE algorithm and compare them with the results obtained by using a capacitance displacement sensor.