Signal Error Detection and Correction of Quadrature Detectors of Laser Interferometers

Errors of laser interferometers using quadrature detectors depend not only on the interferometers themselves, but also on the electronic systems for processing quadrature signals. There are three sources of errors of quadrature detector signals that affect the displacement measurement error: the inequality of the amplitudes of quadrature signals, the phase shift of these signals (not equal to 90°), and the zero offset in each signal. A simple method for identifying and correcting these errors based on experimental data on signals obtained using analog-to-digital converters is considered. The proposed method is applicable to any interferometer with sinusoidal quadrature outputs.