Research On The Electric Laser Beam Expander Driven By Ultrasonic Motor

Because of the advantages of good monochromaticity,excellent directivity and collimation,the laser technology has been applied in more and more places in recent years,such as laser guidance,laser holography,laser cutting and other fields.Usually,the diameter of the beam produced by laser generator is constant,and the original spatial divergence angle is large,which cannot directly meet the applications in some occasions,such as laser ranging and laser communication.The laser beam expander is a device that can expand the beam diameter and reduce the spatial divergence angle,so that the laser transmits after a long distance,we can obtain a required size and imaging quality of the laser spot.The existing laser beam expander is generally driven by electromagnetic motor.The overall structure of such a laser beam expander is complex,bulky,slow in response,and low in control accuracy.As a new type micro motor,ultrasonic motors have the advantages of compact structure,fast response speed and high control accuracy.So it can achieve fast and high precision variable beam expansion of the laser beam if adopt ultrasonic motor as the driving mechanism.In this paper,the principle of the beam collimation are intraduced and analyzed.The structure design and experimental research of the beam expander as well as ultrasonic motor are carried out.The main works of this paper are as follows:(1)This paper summarizes the characteristics,application background and research status of laser beam expanders,and analyzes the shortcomings of the existing fixed beam expander,manual adjusting beam expander and electric beam expander driven by electromagnetic motor,and also expounds the application status of ultrasonic motor in the field of zoom lens,as well as the advantages and practical significance of using ultrasonic motor as the driving source of beam expander in detail.(2)Based on the principles of collimating and zooming,the zoom beam expanding system and the structure of the beam expander are designed,and the force analysis of the relevant parts is carried out.At the same time,a kinematics simulation model of the laser beam expander is established,and collision detection is performed using ADAMS software.The simulation results show that the beam expander runs smoothly and the structure design is reasonable.(3)The hollow rotating traveling wave ultrasonic motor for driving beam expander is designed.Regarding the material of the motor stator,selected phosphor bronze,PPS and phosphor bronzePPS as the stator materials,and the structure of the stator with different materials is optimized.By using the finite element software,the temperature field simulation model of the motor is established,the rule of temperature change with time in the key parts of the motor is obtained by simulation.Finally,the performance of the ultrasonic motor is tested by experiment.(4)The performance of the laser beam expander prototype is tested through experiments.The experimental results show that the positioning error of the movable mirror group is related to the speed of the motor.During experiments,by changing the frequency and phase difference of the working voltage to adjust the motor speed,the relationship curves of the positioning error affected by the voltage frequency and phase difference are obtained.The positioning error is inversely proportional to the voltage frequency,as the voltage frequency increases,the positioning error decreases,and the positioning error increases as the phase difference increases.By measuring the spot size of the laser beam with different beam expansion ratio,the collimated beam expansion performance of the prototype is tested.The experimental results show that the spot size of the outgoing beam is basically consistent with the theoretical value.