Quality Analysis And Optimization Method Of Liquid Crystal Phase-controlled Far-field Beam

Liquid crystal optical phased array is a mainstream technology for purely electronically controlled non-mechanical beam deflection control.Compared with traditional beam pointing control systems,it has the advantages of small size,lighter weight,low energy consumption and fast deflection speed.It is widely used in imaging laser radar and other fields.With the increasing application of high-energy lasers in industry and military,the research on liquid crystal optical phased arrays with high endurance power has become an inevitable trend.Among them,ensuring the beam quality of the transmitted light is a major difficulty.Based on the elastic energy theory of liquid crystal molecules,this paper studies the actual near-field modulation phase of the liquid crystal optical phased array under a certain temperature distribution,and then discusses the deterioration of the transmitted light beam quality by the thermal phase,and then proposes an optimization plan.Finally,we successfully developed a Indicator of liquid crystal optical phased array device.The main contents of this article are:(1)The near-field thermal phase distribution model of liquid crystal phased array under high-energy laser incidence is established.According to the liquid crystal elastomer theory,the spatial distribution of the liquid crystal directors in the liquid crystal phase shifter at a given temperature and voltage is calculated.And according to the principle of electronically controlled birefringence of liquid crystal,the phase under the corresponding conditions is calculated,and then the one-to-one correspondence between voltage-temperature-phase is established.(2)Based on near field thermal phase distribution,the beam quality analysis model of liquid crystal optical phased array is established.Given a temperature spatial distribution and an ideal deflection angle,the actual thermal phase distribution can be quickly obtained based on the established thermal phase model.Then,the finite difference method is used to solve the spatial distribution of the light intensity of the emitted light,and finally an appropriate evaluation standard is used to measure the beam quality of the transmitted light at any place.(3)Two solutions are proposed to reduce the thermal deposition of the device.One is to replace the conductive film material.After temperature rise test,it is found that the transmittance of the new material Ci O is much better than that of ITO;the other is to use a double-layer liquid cooling model to dissipate the heat deposition on the surface of the device in time,and build a corresponding the thermodynamic model simulates the heat dissipation effect.(4)Prepare a complete liquid crystal optical phased array device and test the phase and beam quality.After a variety of processes,a liquid crystal optical phased array was successfully manufactured,and a high-power tunable laser was used to measure the phase of the device,and then a semi-physical simulation of the beam quality was established based on the beam quality model.Finally,we compare the theoretical results with the actual measurement results and draw conclusions.