Application Research on the Point Diffraction Interferometer (PDI) for Testing Large Optical System

摘要

@@A new approach for testing the wavefront of the large optical imaging system is proposed. Meanwhile, the technical indexes and adjustment characteristics of the equipment components are analyzed. Extended abstract The large-aperture optical imaging system is widely used in the astronomy observation, due to its long work distance and superior resolution characteristic. The troubles brought by its intrinsic character: large aperture and long focal distance also appears in machining, alignment and testing process. Laser is used in the optical testing because of its outstanding temporal and spatial coherence. Interferometric method is applied in the optical wavefront evaluation. This method has good accuracy at estimating the character of the optical imaging system. At present, the commercial optical interferometer is mostly based on the Fizeau interferometer principle. In the Fizeau interferometer, the reference wavefront will emerge from the criterion lens, and the testing light which contains the information of the tested wavefront will interfere with the reference light, finally, the tested wavefront could be characterized. In the classic wavefront testing method, the autocollimation approach is applied. In that case, a plane mirror with the same caliber of the optical imaging system is necessary. Hence, in the test of optical imaging system with large aperture, manufacturing plane mirror with large size is becoming very difficult. Due to its processing difficulty and high cost, manufacturing plane mirror with large diameter (diameter is larger than 1. 5 meters) is being a technical difficulty in the large diameter optical manufacturing.