Can Be Used For Transient Laser Wavefront Distortion Of The Real-time Detection Technology

The research of Inertial Confinement Fusion (ICF) technique is helpful to solve the problems of resource in future on earth and improve the pollution in the environment. The work based on the supporting many subjects such as optics, mechanics and electronics etc. It is a critical part to measure the wavefront distortion and divergence of pulse laser because the wavefront quality of the laser beam ultimately determines the focus ability of pulse wavefront. The thesis described some research work such as the system of a radial shearing interference being suited to measure static and dynamic wavefront, the reconstructed technique of the radial shearing wavefront and the processing technique of measuring data and the image. Main research work and new ideas as below:The importance of qualifying the wavefront distortion in ICF system is recounted. A number of sensing techniques of wacefront are analyzed and a radial shearing interference system with spatial linear carrier modulation suited to static and dynamic wavefront. A basic experiment device has been set up.In terms of the concept of relative sensitivity of measurement and the size of beam aperture of input system and the amount of the wavefront distortion, the radial shearing ratio relation with the magnification of a telescope is derived. A mathematic equation of Strehl ratio based on a amplitude model has been derived from the character of pulse laser and KirchhofFs diffraction theory.The most important error source in DFT method of the reconstructed wavefront is energy leakage effect. How to result in leakage and reduce the error are discussed in chapter 3 both modulation filters of Hamming and Pyramid windows are respectively applied to circular and rectangular pupils. Especially it is useful that Pyramid filterto rectangular elements in ICF can efficiently reduce the frequency leakage and obtain finer reconstructed wavefront. At the same time determining the amount of linear carrier f0, the width of filter of+1 order spectrum and slope at space domain result from the error of shifting +1 order to origin at frequency domain, which are analyzed in all details. Two methods that can carry out the reconstructed of radial shearing wavefront of iteration and analysis with Zernike orthogonal polynomial fitting are discussed. The mathematic models, physical explanations and data simulations of these algorithms are alldemonstrated in chapter 4. The accuracy of root-mean-square values of data simulations can be better than (2-3)71000 wavelength.To set up an experiment device of radial shearing interferometer with spatial linear carrier and carried out a series of data processing from DFT, IDFT, unwrapped, removed the slope to iteration or Zernike polynomial fitting. The results of wavefront measured are identical with practical conditions. The theoretical derivations and measurement results showed that the sensing system in thesis can attain a RMS accuracy of 1/10 ~ 1/20 wavelength.