Studies On Image Evaluation Techniques Of Long Focal Lens

In the driver of the Inertial Confinement Fusion (ICF), the spatial frequency filter is the important module of system, with functions of filtering out high-frequency noise, enlarged beam and image relay, but high-accuracy measurement of focal length and wavefront of long focal lens which composed one is difficult on test of optical components in ICF. Presently adopted test method is traditional one, which is the knife edge method, and its main defect is that it doesn't take quantitative measurement, and need large workspace with longer focal length. Furthermore, a kind of new testing method with quantitative result, scanning measurement based on the Talbot effect of Ronchi-grating, has been studied. The main research results have been summarized as follows:1, Concerned information of laser fusion is introduced in brief, and it is set forth that the optical quality evaluation and key standard of optical components, and the function of long focal lens In the driver of ICF.2, The traditional method that focal length and wavefront of lens is measured is introduced in brief, especially emphasized a new testing method of focal length, long focal length measurement based on the Talbot effect of Ronchi-grating , and do the knife edge method on wavefront of long focal lens.3, It is discussed that the effect of the temperature on the stability of the measuring system of long focal length, which is made based on Talbot effect of Ronchi grating. The method is obtained by large numbers of experiment that this effect is weakened, the stability is advanced 8 to 10 times than the unimproved measuring system.4,It is presented that scanning measurement method based on the Talbot effect of Ronchi-grating, which measures focal length of the different part area of long focal lens by the measuring system of long focal length, and this method may take quantitative measurement on wavefront of long focal lens. Scanning measurement model and data processing program has been presented, and the result of experiment demonstrates that this method is feasible.5, the measuring precision is analyzed that the scanning measurement system based on the Talbot effect of Ronchi-grating, and the factor that effect on the testing precision is set forth.6, The large numbers of scanning measuring experiment have been done by above measuring system which is based on the Talbot effect of Ronchi-grating. The result of experiment compared to the knife edge method, wavefront distortion is similar, and the difference is the new method may have quantitative testing result.All of the results included in this dissertation are very useful both in the theory and the engineering application of the ICF system.