提出了一种新型的非零位环形子孔径拼接干涉检测技术（NASSI）用以检测深度非球面面形误差。该方法结合了传统非零位干涉检测法与环形子孔径拼接法，采用部分零位镜替代了标准环形子孔径拼接干涉仪中的透射球面镜，产生非球面波前用以匹配被测面不同子孔径区域。该非球面波前比球面波前更加接近被测面的名义面形，使所需的子孔径数目大大减少。一方面增大了环带宽度和重叠区，提高了拼接精度；另一方面减少了各种误差累积次数。同时，配合基于系统建模的理论波前方法分别校正各个子孔径的回程误差，进一步提高了检测精度。对非球面度为25 μm的高次非球面的计算机仿真检测结果表明该方法具有很高的理论精度。针对口径101 mm的抛物面进行了实验检测，多次实验结果均与Zygo VerifireTMAsphere干涉仪检测结果一致，峰谷(PV)值误差优于λ/20，均方根(RMS)值误差优于λ/100，表明了NASSI方法的高精度与高重复性。

A novel non-null annular subaperture stitching interferometry (NASSI) is proposed for steep aspheric test. It combines the non-null test and annular subaperture stitching method, in which a partial null lens is employed as an alternative to the transmission sphere, to generate aspherical wavefront as the reference. The aspherical wavefront has a better performance in matching the local slope of subapertures. This approach greatly reduces the subaperture number required to cover the full-aperture of test surface. On one hand, subapertures are broadened and thus the stitching accuracy increased. For another, accumulated error is decreased. Based on the system modeling, the retrace error can be corrected for each subaperture individually and the testing accuracy is further improved. A numerical simulation exhibits the high theoretical accuracy of the NASSI method, in which a high-order aspheric of 25 μm asphericity is tested. Comparing experiments with Zygo VerifireTMAsphere interferometer for paraboloid, whose diameter is 101 mm, are performed. The peak-valley error is better than λ/20, the root-mean-square error is better than λ/100. The high accuracy and good repeatability of NASSI are presented.