Non-null interferometric system for general aspheric test

Aspheric design and fabrication have obtained great achievements with the fast developments of modern science and technology, especially computer science, while the test of aspherics has become a chief limitation of aspheric applications. Due to the arbitrary nature of aspherics, test of all aspherics with only one instrument seems impossible. This paper presents a non-null interferometric system that can be applied for general aspheric test. The systematic error of non-null aspheric test system is studied, according to which an error separating and correcting method is proposed then. Computer simulation shows the error correcting method can correct the systematic error of non-null aspheric test system effectively and efficiently. Experiments have been carried out with the proposed interferometric non-null aspheric test system and the results show the system can greatly increase the accuracy of the non-null aspheric test.