Nonlinear errors caused by mis-installation of common-path heterodyne interferometer affected the measurement precision of the system.
共光路外差干涉仪具有很高的分辨率，但因为安装、调试误差会产生非线性误差，影响系统的测量精度。
The design of common path makes the measurement beam and the reference beam incident on the surface along the same way.
共光路设计， 使测量光和参考光沿同一路径入射到被测表面上。
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