由于非共光路误差是菲索干涉仪进行高精度检测中最重要的误差因素之一，而非共光路误差是由于非理想的光学系统即干涉仪的出射波前不理想造成的，所以为了测量干涉仪的出射波前来评估干涉仪非共光路误差的大小，提出一种利用干涉仪猫眼位置绝对测量干涉仪出射波前的方法。该方法基于干涉仪自身的面形测量功能，操作非常简单，只需要一块反射镜就能够实现干涉仪出射波前的测量。该方法通过至少三个猫眼位置的测量得到干涉仪出射波前的自身剪切数据，然后通过基于旋转平移的绝对检测算法直接得到干涉仪的出射波前的二维波前数据。实验结果表明：该方面能够实现不包括Power在内均方根(RMS)值约为15 nm 的测量精度。该方法能够准确测量干涉仪出射波前，从而评估干涉仪非共光路误差。

The retrace error is one of the most important factors for high precision testing of Fizeau interferometer. The wavefront of interferometer is the mainly factor of retrace error. So in order to measure the wavefront of interferometer, a method of testing the wavefront of interferometer is proposed, which is based on the measuring function of interferometer itself and is very easy to carry on. Just an additional reflection flat is needed. In this method at least three cat,s-eye test results are used to get shearing of the wavefront, which is used to solve the wavefront map by shift-rotation absolute testing algorithm. Experimental results show that the wavefront testing uncertainty is about [root mean square (RMS)] 15 nm without the Power term. It can be utilized to test the wavefront quality of interferometer precisely, and the retrace error farther.