Study Of LCLV's Phase Modulation And The Application In Real-time Wavefront-conversion System

In laser's practical application,people usually need to convert the wavefront of the laser to change the intensity distribution according to different requirements.For example, in laser processing,heat treatment and inertial confinement fusion(ICF),laser spot with various shape and variable size is often needed.So,the laser conversion technology has broad application prospects,we can also convert the laser's wavefront by using the binary optical pure-phase element with relief structure,however,the process is complex and quite expensive.This paper mainly involves the research of a wavefront-conversion system based on the phase modulation of TFT-LCD which is relatively simple and cheap.This paper introduces the creation,development and progress of the wavefront-conversion technology,and analyses the optical and electro-optical properties of the liquid crystal,and carries on a research on the structure and working principle of TFT-LCD,moreover,it offers two popular algorithms used to convert wavefront in a detailed way,also gives an theoretical derivation of the TFT-LCD's phase and amplitude modulation characteristics,then measures the parameters and phase modulation characteristics of the TFT-LCD by using double-slit interference method.We obtain the relation between relative phase and gray scale through curve fitting.We also discuss the feasibility of TFT-LCD as a phase modulation element through the hollow beam experiment.The fourth chapter of the paper put forwards a real-time wave-conversion system based on the phase modulation characteristics of the TFT-LCD,and also does some corresponding experiments:to convert the Gaussian beam to the box-shaped beam,we get the phase distribution with the geometric theory,which we turn into gray level image displayed on the TFT-LCD's screen.The experimental results provide expected diffraction pattern;the paper also gives the simulation results.With combination of scalar theory,the system convert the Gaussian beam into the triangle-shaped and elliptic-shaped beams,like the geometric theory,we obtain the phase distribution of the corresponding binary optical element(BOE),which we change into gray level image displayed on the TFT-LCD's screen through the above gray-phase relation.The experimental results provide expected diffraction pattern,the paper also gives the simulation results.The paper concludes and compares the results based on the above two experimental results,analyses their difference and points out where the error comes from and the effect of the error on the experiments,which has some reference meaning.