3ω laser damage of fused silica optics is the bottleneck of high power laser systems for ICF. Excellent beam quality plays an important role in improving the anti-damage capability of final optics system. We have developed a new optical field measurement technology based on computational optical imaging. With the high power laser prototype of SGII-UP facility, damage resistance of final optics was experimentally studied. The near filed of laser beam was measured with a high resolution to study the effects of modulation and propagation on laser damage. The near field improvement of high power laser beam are reported and the influence of near filed quality on damage performance of final optics are discussed. The development of the defect detection techniques of final optics are introduced. Finally, we present the development perspective of final optics system for ICF laser driver. At present, the damage resistance capability of final optics assembly is 6J/cm<sup>2</sup> at normal operation, we will continue to improve the ability in the next step of work.
We propose an optical diagnosis for plasma electron density measurement with the Coherent Modulation Imaging(CMI) method which is a kind of phase retrieval technique and doesn’t need a reference beam. The phase of the diagnostic light can be reconstructed by CMI algorithm. The distribution of electron density can be obtained by dealing with the phase change using Abelian integral formula. Experimental results showed that the area where the plasma generated is ejected from the center. As the energy of laser driver beam increases, the phase difference region resulting from the generation of the plasma becomes larger.