Study On A Wavefront Detection System Long-focus Lens By Sub-wavefront Scanning

Long-focus and large-diameter lens is the most important component of the ultra-high-power laser system, which is of great significance to solve the increasingly serious energy problem. There is still no effective way to detect its wavefront. To solve this problem, a new method, using sub-wavefront scanning, is proposed in this paper. And a prototype is designed and its installation and commissioning is finished.The proposed method can be divided into two steps. Firstly using sub-wavefront scanning, the images of moire stripes are sampled. The wavefront slope data could be gotten with digital image processing technique. Secondly, we used the mode method with Zernike polynomials to reconstruct the wavefront of the whole aperture. When the prototype is being designed, considering the actual situation and account precision, several methods are proposed to control the prototype's accuracy, such as return-checking, iterative reconstructing and etc. These methods improved the data reliability and stability.Due to the installation and environment constraints, interferometer could not detect a lens with a very long focal length. To verify our proposed method and prototype, we chose a flat concave lens with a 10m focal length to test, which can still be measured by interferometer. Through the comparison with WYKO Laser interferometer, the result is correct. Also, accuracy analysis is involved in the paper. Simulate the reconstruction after introducing external disturbances. The result shows that the measuring prototype could be used in the actual situation to provide a reference for the producing of long-focus and large-diameter lens.The main task of the paper:First, finish the analysis of the sub-wavefront scanning method. Second, complete the prototype and its software which used to control all the processing of measurement. Third, finish the accuracy analysis.