外差激光干涉仪能够通过光波细分达到亚纳米分辨率，因而在科学研究和精密机械制造中得到了广泛应用。然而，由于光学系统中不可避免的缺陷，导致被测信号中出现一个附加的相位误差，使测到的相位移和被测长度不呈线性关系，成为现有激光干涉仪难以逾越的精度极限。为此，通过光学相位补偿理论的研究得出一种消除激光干涉仪非线性误差的方法，它可以应用在大部分科学实验和工业制造中的纳米长度测量中，而且不论是一阶或二阶误差都可以通过这个方法被消除。

The heterodyne laser interferometer can achieve a sub-nanometer resolution on the basis of a stable subdivision of the light wavelength using phase measurement. However, due to inevitable imperfectness in optical system, a phase error occurs in the measurement signal and results in a nonlinear relation between the measured phase difference and the respective displacement. Based on the optical phase compensation theory, a significant approach is found to eliminate the nonlinearity of laser interferometer. This method can be used in most science researches and the industry precision nanometer measurement, and it is valid for nonlinearity errors whether it is a one-order or a two-order error.