The invention belongs to the field of optical
heterodyne interference, and discloses an optical
heterodyne interference method for removing a non-linear error based on a
square wave mean value method. The method comprises the steps that at least three paths of signals are obtained from an
optical path where non-linear error interference elements exist, phase angles, on
signal frequency elements to be removed, of the periodic non-linear error interference elements of the at least three paths of signals are made to be different in a corresponding circumference angle range or in a corresponding circumference angle range after integral multiples of circumference angles are removed, meanwhile, signals are filtered through a filter in an analog electrical
signal channel, a
phase difference between each path of measuring signals and a reference
signal is computed by the adoption of the
square wave mean value method, and then analog-
digital conversion, displacement calculation, weighting and iterative
processing are conducted so as to remove or restrain the interference elements conveniently. The optical
heterodyne interference method for removing the non-linear error based on the
square wave mean value method can remove specific
harmonic elements of the non-linear error or the interference, the regulation process is very easy,
system performance is improved, and cost is reduced.