LASER INTERFEROMETER COMPENSATING APPARATUS USING EXTENDED KALMAN FILTER

摘要

PURPOSE: A laser interferometer compensating apparatus using an extended kalman filter is provided to enable high-precision measurement by removing frequency mixing and errors resulting from the frequency mixing in a heterodyne laser interferometer for nano-scale measurement. CONSTITUTION: A laser interferometer compensating apparatus comprises an Ir operation unit(210), an Im operation unit(220), a pre-preprocessing unit(230), a database(260), and an extended kalmam filter(240). The Ir operation unit creates a reference signal from the signal inputted from a heterodyne laser interferometer. The Im operation unit creates a measurement signal from the signal inputted from the heterodyne laser interferometer. The pre-processing unit receives the reference signal and the measurement signal and outputs a signal including phase information. The database stores noise dispersion information of the extended kalmam filter. The extended kalmam filter corrects an error using the noise dispersion information of the database and information on the moving speed of a target object in the heterodyne laser interferometer.