由于相移式横向剪切干涉不需要标准参考波面，因此它可以缩小干涉腔长、甚至实现绝对的共光路干涉，从而最大程度上降低了空气扰动和振动的影响，但实验室设计的相移式横向剪切干涉测量装置中的分束棱镜、剪切平板和五棱镜的制造误差仍然造成了发生错位的两波面间产生非共光路误差。通过剪切干涉测量装置中调整误差和非共光路误差的对比分析，提出了非共光路误差的计算方法，并在测试结果中进行非共光路误差的补偿。实验结果发现补偿非共光路误差后的面形误差与ZYGO干涉仪的测量结果非常接近。

Because standard reference wave-front is not needed in lateral shearing interferometry(LSI), interferometry cavity can be shorten, even absolute common path interferometry could be achieved, and it is immunity to air turbulence and vibration. Therefore, non-common path error between two shearing wave-fronts which come through different cubic prisms, shear plate and pentaprism is not avoided. In this paper, calculation method of non-common path error was proposed by contrast analysis between adjustment error and non-common path error in shearing interferometry, and non-common path error in surface measurement result was compensated. Lastly, experiment results demonstrate the surface result after compensation is in accordance with ZYGO interferometer.