In laser interference measurement, if an amplitude error, a phase error and an offset error are in the two phases sine wave signals which is the output of a laser interferometer, the uncertainty of the position which interpolated below the laser wavelength interval increases.This paper describes the technique of reducing the uncertainty of the interpolated position by presuming the position below a wavelength interval from two phases sine wave signals which compensated the amplitude error, the phase error and the offset error. Furthermore, it was shown that the uncertainty of the calibration below a wavelength interval can be presumed based on two phases sine wave signals.
