Research Of Laser Small-scale Distorted Wavefront Measurement And Control

The diagnosis and control of small-scale distorted wavefront is a key issue in the field of high power laser system, which play a role in laser transmission and amplifying. We study the feasibility of small-scale distorted wavefront measurement and control. The Fresnel zone plate arrays and liquid crystal spatial light modulator (LCSLM) have been applied in the thesis. The main work and obtained results can be summarized as follows:1. We analyze the effect of small-scale distorted wavefront in the field of high power laser system. According to the principle of Hartmann- Shack wavefront sensor (HSWS), we put forward the Fresnel zone plate arrays as wavefront sensor. And the optical characteristic of LCSLM and the feasibility of LCSLM controlling small-scale distorted wavefront are analyzed.2. We depict the principle of HSWS and analyze the characteristic of the Fresnel zone plate arrays in distorted wavefront measurement. The errors of HSWS in wavefront measurement are analyzed. We analyze the focus characteristic of the Fresnel zone plate array and present the algorithm of fractional Fourier transforms to stimulate the diffraction of laser beam. The experimental results about laser beam's focus are given in the same time, which prove the effective of diffraction algorithm proposed in this thesis.3. We discuss the Southwell model of zonal wavefront reconstruction in detail. The Southwell model is proved a high precision wavefront reconstructed algorithm. The relations between the precision of wavefront reconstructed and the parameter of wavefront sensor are studied. The improvement of wavefront reconstructed is discussed under the condition of asymmetric intensity and circular and super Gaussian laser beam.4. We build an adaptive optical system for the measurement and control of small-scale distorted wavefront, which consists of Fresnel zone plate arrays and LCSLM. The experiment results of wavefront measurement and control of laser beam are given. The elementary experimental results show that the small-scale distorted wavefront can be detected and controlefficiently.According to these researches, we can declare that the Fresnel zone plate arrays can be used to detect small-scale distorted wavefront in high precision and LCSLM can be used to control small-scale distorted wavefront efficiently. These techniques can be applied to laser engineering.