| Micromirror is a kind of important optics in Micro-Optical-Electro-Mechanical-System,which is widely used in civil field and military field such as optical systems,NMEMS optical switch,precise measure system,medical imaging,aerospace and so on.For the problems causing by requirement of complex accessorial devices and connecting wires,such as producing electro-magnetic interference easily and cannot being operated in an isolated environment,the basic research on light-activated micromirror drived by PLZT ceramic and control strategy of optical excitation are carried out.Compared with the traditional actuator of micromirror,the light-driven micromirror using PLZT ceramic does not require hard-wire connections to extra power,and have advantages of clean driving,remote light-driven and free from electromagnetic interferences.Therefore,the light-driven micromirror is suitable for remote non-contact control in an isolated environment,such as the clean operating space and vacuum environment.In this paper,the photo-induced characteristics and influence factors of 0-1 polarized PLZT ceramic,the mathematical model of photo-induced multi-physics coupling fields,improving measures of driven performance and novel optical driving mechanism,the structure design of light-driven micromirror and principle experiments of control strategies are carried out by using theoretical analysis,computer simulation and experiment,which can provide the theoretical base for engineering applications of optical controlled smart material and structure.The hysteresis phenomenon between the photovoltage and photo-induced deformation and their changing laws in illumination phase,the reverse voltage between the two electrodes and the residual voltage and deformation during light switched off phase are researched by photo-induced characteristics static experiments;According to the results of hysteresis factors experiments,the temperature elevation of PLZT ceramic caused by photothermal effect is verified as the main reason of the hysteresis phenomenon between the photo-induced voltage and the deformation,and the temperature elevation is thought should not be neglected when the mathematical modeling of PLZT ceramic is established.The coupling relationships of the electrical,thermal,mechanical and light fields in a 0-1 polarized PLZT ceramic are rigorously analyzed and the mechanism of the anomalous photovoltaic effect,the pyroelectric effect and thermal expansion are investigated theoretically,based on which the mathematical model of photo-induced multi-physics fields coupling are established,and the equations of photovoltage and photo-induced deformation are derived,by which both the changing rule of photovoltage and the hysteresis phenonomen between photovoltage and photo-induced deformation can be explained theoretically.According to the results of photo-induced characteristics static experiments,the mathematical modeling is validated that can accurately describe the changing rule of the photo-induced voltage and deformation during both the illumination phase and light switched off phase.In order to improve the response speed of photo-induced deformation and eliminate the significant residual photovoltage and strain,three improving measures,such as avoiding the temperature elevation,connecting to the ground or driven by another PLZT ceramic after illumination,are preposed and verified effective by experiments.According to these improving measures,two novel optical controlled driving mechanisms are presented and analyzed theoretically,and the expressions of output force and deformation that are in terms of light intensity and illumination time are studied.A cantilever beam actuator driving by PLZT bimorph is presented,and its output force and deformation are derived and calculated theoretically,the influences of thickness and Young modulus of elastic beam on the output performance are evaluated.On the basis of the discussion of solution selections for the light-activated micromirror,the overall design scheme of micromirror with four DOF of x-y-?x-?y is given.The key parameters of translation agency,such as stiffness,actual amplification,output deformation and natural frequency are analyzed and calculated,on the base of which,the geometrical parameters of translation agency are determined,and the finite element simulation is done.The rotation angle of photovoltaic-electrostaic hybrid actuated micromirror is derived,and the relationship between rotation angle and photovoltage is studied by the analyses of numerical example.In order to verify the feasibility of novel light controlled hybrid driving and the effective of control strategy of optical controlled micromirror servo system,the principal experiments of control strategy are conducted.The ON-OFF control strategy modeling of photo-induced deformation of 0-1 polarized PLZT ceramic is established,and the related paremeters are identified through photostrictive static experiments,and the ON-OFF control simulation of photo-induced deformation is conducted by MATLAB sortware.And then,the experimental platform is set up,the ON-OFF control strategy experiment of photovoltage and photo-induced deformation produced by a single 0-1 polarized PLZT ceramic,and the dual light source control of photovoltage generated by PLZT bimorph are conducted.Experimental results show that the photo voltage and photo-induced deformation of single 0-1 polarized PLZT ceramic can be controlled with a high dynamical control precision,and the photovoltage of PLZT bimorph can be controlled quickly.Thus the proposed novel optical control driving mechanisms are feasible and the control strategies are effective. |
PDF Full Text Request