针对方形孔径自由曲面反射系统，构造方形域上正交多项式用于波前解析，得到方形孔径系统波像差系数。在计算机辅助装调阶段，为确保装调结果准确，用方形域上正交多项式和光学设计软件来建立系统的灵敏度矩阵，结合自准直干涉法得到的多个视场得波像差来求解系统失调量；在多次迭代后得到系统平均RMS为0.164 1(632.8 nm)实测系统平均传递函数达到0.453 4的理想结果；证明该装调方法正确性，并适用于其他形状孔径自由曲面离轴反射系统式系统装调。

In accordance with a three mirror off-axis freeform square aperture system, orthogonal Zernike polynomial in square area was created to analyze wavefront and receive aberration parameter. During computer-aided alignment, by collecting interferograms of several fields of optical system by means of autocollimating interferometry, aberrations could be obtained from those interferograms. Furthermore, the sensitivity matrix related to the incorrect parameters derived from optical design software and these parameters of orthogonal polynomials in square area were used to determine the incorrect parameter. The results show that the averaging RMS value of the system is 0.164 1 waves(632.8 nm) and the averaging MTF value of the system is 0.453 4 after iterations, which proves it is right, and it can be used in off-axis freeform reflected system with other types of aperture.