System Design And Precision Analysis Of Double Sensitivity Imaging VISAR

With the development of laser technology, laser velocity interferometer technique has become a primary means to measure free-surface velocity or partical velocity, and VISAR(Velocity Interferometer System for Any Reflector) is the most advanced one of which. It is a kind of velocity interferometer that based on changes in the reflected optical phase.Over the past thirty years, VISAR was widely used in the field of Inertial Confinement Fusion (ICF) among many nuclear-powered countries, and has become the standard velocity diagnostic for a variety of experiments involving laser-driven shock-wave propagation, high-pressure equation of state experiments, materials characterization experiments, and shock timing experiments for ICF research. With the development of ICF, several high-energy laser drives were built at home. So it is urgent to develop VISAR for our own experiments.This paper focuses on establishing a VISAR used in "SG-III" laser fusion facility prototype and includes some research on system design, precision analysis and static and dynamic experiments. Main contents as following:1. Discussed the theoretical foundation of VISAR technology, and deduced the formula of velocity measure based on Doppler-shift and optical mixing.2. Solved the problem of stripe losing of the traditional VISAR, which is a non-imaging single point testing system and can not meet the demanding of ICF shock-wave research. Established a double-sensitivity imaging VISAR, which includes double interferometers and gains more information in experiments.3. According to the practical requirements of experiments, designed the lighting, imaging, interfering and recording of system. It can measure velocity ranged from 6km/s～60km/s, the sensitivity is 0.2km/s and the ambiguity is less than 2%.4. Studied the miain factors of precision. The analysis shows that the reading error of stripe, which is mainly influenced by the contrast of strip, plays the most important role.5. Analysed the relationship of the surface error of optical accessory and the contrast of strip, and educed the proper surface error according to the requirement of precision.6. Made some static and dynamic experiments respectively in lab and practical atmosphere and did some research on the results.