Structure Design And Performance Research Of Modular Voice Coil Deformable Mirror

When using ground-based optical telescope for astronomical observation,it is often affected by atmospheric turbulence,resulting in poor imaging quality.The adaptive optics（AO）technique can solve this problem very well.As a wavefront correction device,the performance of deformable mirror（DM）determines the correction effect of the whole AO system.Compared with traditional piezoelectric deformable mirror,The voice coil deformable mirror driven by electromagnetism has the advantages of large stroke,high frequency response,high precision and no hysteresis.At present,this technology has been successfully used in many applications including many large aperture optical telescope systems abroad,and there is little research on it in China.Based on this background,a new structure of non-magnet and contact-less magnetoresistive voice-coil actuator based on the structure of voice-coil actuator is presented.The deformable mirror is modularized and the feasibility of the scheme is verified by finite element simulation and analysis.The specific contents are as the follows:（1）A structure of magnetoresistive voice-coil actuator is presented and designed.And its working principle is explained,the formulas of driving force and efficiency are deduced.In addition,the structural dimensions of each component are optimized.Finally,the results show that the obtained axial output force of the actuator is 3.4N and the efficiency of the actuator is9.05 N·W^-1/2,the performance is greatly improved compared with the voice-coil actuator of the same level(the efficiency is about 1N·W^-1/2).（2）A modular voice-coil deformable mirror model with 121 units is designed.Each module has 7 magnetoresistive voice-coil actuators with a sawtooth hexagon structure.The deformable mirror is compact with 91%actuator utilization,while other module types are discussed.This work provides an idea for the modular design of deformable mirror.（3）Based on the model designed in this paper,the performance parameters of deformable mirror are studied,in which the actuator can provide 1m stroke in 0.03ms;It is found that the distance between adjacent actuators has no effect on the working performance of their respective actuators.The relationship between actuator distance and coupling is analyzed to determine the best actuator distance for the deformable mirror is 15mm,at which time the coupling of the deformable mirror is 11.7%,which meets the requirements of the system.（4）The surface shape influence function of the modular voice-coil deformable mirror is analyzed by using the finite element simulation method.and the Gaussian function model is supplemented according to the actual situation,and the parameters values of the Gaussian function are calculated;the correction ability of the designed deformation mirror for the primitive aberration is studied,and the results show that the fitting error of astigmatism,clover and coma is less than 50 nm,which verifies that the the good performance of the deformation mirror.Through the modular design of deformable mirror and the design of voice-coil actuator used in the deformable mirror,this paper preliminarily verifies the superiority of the designed structure,explores a design method of deformable mirror,and accumulates experience for the development of super multi-unit deformable mirror of adaptive system,in which the high-efficiency magnetoresistive voice-coil actuator increases the output force and means lower power consumption.The concept of modular design reduces the engineering manufacturing difficulty of deformable mirror,which has strong practical significance.