Research On High Beam Quality Laser Zoom Beam Expanding Technique Based On LC-SLM

The laser beam expander system is widely used in the fields of national defense and national economy such as laser communication and radar tracking.In order to meet the requirements of laser beam diameter in different fields and different equipments,the beam ratio continuously variable system is required.The traditional mechanical laser zoom beam expander system has the disadvantages of complex structure,low precision,slow response and low image quality.Therefore,this paper has made a new exploration of the variable beam expansion method of the laser beam expander system.The Liquid Crystal On Silicon Modulator(LC-SLM)was applied to the laser beam expander system.The high beam quality laser zoom beam expanding technology based on LC-SLM was studied.Firstly,the zoom control technology based on LC-SLM was studied,and the LC-SLM zoom lens system was built.By using the gradation signal of the phase modulation diagram of the zoom lens with different focal lengths to control the voltage variation of the LC-SLM,the zoom lens function based on the LC-SLM was realized,and the zoom beam expansion of the laser beam was realized by using this function.Secondly,the wavefront aberration correction technology based on LC-SLM was studied,and the wavefront correction experiment system based on LC-SLM was designed.The ability to simulate wavefront aberration based on Zernike polynomials by using LC-SLM was verified and analyzed.The wavefront aberration of the aberration plate was corrected by using LC-SLM.The PV value was reduced from 1.583 ? to 0.116 ? after correction,and the RMS value was reduced from 0.137 ? to 0.032 ? after correction,aberration correction effect was obvious.Finally,a compound control method based on LC-SLM for laser beam expansion and beam quality improvement was proposed,the feasibility and effectiveness of the compound regulation method were verified and analyzed by experiments.A beam expansion system with a simple structure,high accuracy,fast response speed and good beam quality was designed.The experimental results show that the laser beam expander system based on LC-SLM could achieve continuous zooming after the compound control,and the system aberrations after LC-SLM correction were less than 0.11?,which ensures the system image quality.Satisfy the expected indicators to be achieved in the experiment.