Research On Electronically Controlled Liquid-crystal Micro-cylinder-lens Based On Planar Nonuniform Spiral Micro-coil Array

To conventional optical imaging system,the focal length can be adjusted by changing the axial distance between the lenses used.But,several drawbacks including the large volume and mass of common optical structures,relatively large operation inertia,being difficult to fast respond to external influence,being easy to shift position or deform the shape under the high speed moving or strong vibration conditions,being difficult to real-time reset and calibrate and also insufficient of control-light capability,are still existed.In order to realize the aim of flexibly adjusting focus and then miniaturizing optical structures and high control-light efficiency,the electronically controlled liquid-crystal micro-cylinder-lens?ECLCMCL?based on planar non-uniform spiral micro-coil array is proposed in this thesis.The ECLCMCL has dual-mode converging beam character and can also be used to electronically tune focus.In the"Mode-2"or"Current-driving Mode,the ordered inclining of liquid-crystal?LC?directors can be performed by a magnetic-field generated by the micro-coils used and a magnetic induction electric-field to achieve a cylindrical lightwave focusing and also an arrayed micro-beam-line converging between adjacent spiral micro-coil electrodes,which remarkably enhance the lightwave focusing performance of the ECLCMCLs.The main work of this thesis is as follows:Firstly,the modeling and simulation of the ECLCMCL were carried out based on the physical properties of nematic LC materials for performing control-light operation and electronically controlled LC microlens theory.The distribution of LC molecular directors and the phase delay induced by an applied electric-field are analyzed and then the structural parameters of the ECLCMCLs are configured through simulating the patterned circular-aperture electrode.By analyzing the needed structural parameters of the ECLCMCL,a planar non-uniform spiral micro-coil structure is proposed and the simulation is carried out for sparse circular micro-coils and square micro-coils,respectively.The magnetic-field and its energy distribution from the non-uniform spiral micro-coils driven by current signals applied and the non-uniform electric-field for driving LC molecules are analyzed and evaluated.Secondly,a glass substrate pre-coated by a film of indium tin oxide?ITO?on both surfaces is pre-treated through laser spotting and further embedded by indium particles to electrically connecting the upper and lower electrode film so as to ensure electrical connectivity under the"Mode-2".The pre-treated substrates were utilized to fabricate the micro-cylinder-lens device according to standard micro-nano-processing.Considering the narrow line width of the micro-coils,the ICP dry etching is used to ensure the integrity of spiral electrode line.The optical characteristics of the ECLCMCL based on planar non-uniform spiral micro-coil array electrode under both working modes are analyzed in detail.In"Mode-1":by connecting the upper and lower electrode film of the LC micro-cavity,the electronically tunable focusing of incident beams are discussed carefully,including the focal length being smaller gradually with the increasing of the voltage signal applied and the focal length ranging from 5.09 to 4.31mm.In"Mode-2":through connecting the upper and lower surface of a single electrode plate in the LC micro-cavity,the electrically tunable focusing properties are analyzed,including the typical character of the constant voltage of 45.6V_rms corresponding to a focal length of 1.75mm.Under the"Current-driving Mode",the arrayed micro-beam-line converging between adjacent spiral micro-coil electrodes can be formed,so as to significantly improve the beam focusing efficiency of the ECLCMCL.To several problems existed,the methods for further improving the focusing efficiency is proposed.