| The Bessel beam was proposed in 1987,and has become a research hotspot because of its non-diffraction and self-recovery characteristics.It has been used in laser processing,optical tweezers,and optical communications.However,how to improve the Bessel beam quality and "diffraction-free" length has become the focus of the promotion of Bessel beam applications.Among the many beam shaping techniques,the shaping technique based on adaptive optics can not only achieve Bessel beam shaping with different parameters,but also correct aberrations caused by the surrounding environment and optical elements in the beam system,thereby ensuring the beam shaping Bessel beam quality.As a beam shaping device in adaptive optics,anamorphic mirrors have the characteristics of flexible control and high light energy conversion efficiency,and have important development prospects.More common deformable mirror include electrostatic thin film deformable mirror,electromagnetic deformable mirror,piezoelectric stack deformable mirror,and piezoelectric sheet deformable mirror.Piezoelectric deformable mirror,as a type of deformable mirror,are widely used in adaptive optics due to their fast response speed,low cost,and high damage threshold.Based on the adaptive optics system,this paper uses a single piezoelectric deformable mirror to study the Bessel beam quality and shaping.The specific research work is as follows:(1)Design and construction of Bessel beam experiment platform.Analyze the Bessel beam generation principle and design an adaptive optical system based on a deformed mirror.The control system uses the wavefront information fed back by the wavefront sensor to control the anamorphic mirror to reconstruct the target phase to achieve beam shaping.In the experiment,a beam shaping experimental platform based on a 61-unit single-piezo deformable mirror was used.The beam distribution recorded by the CCD camera was used,and the overall control accuracy of the system was on the order of nanometers.(2)The effects of anamorphic mirror actuators and beam incident angles on Bessel beam quality were studied.When the number of actuator rings is increased from 3 to 5,the rms residual error error of the reconstructed 10 ?m amplitude cone phase is reduced from 70 nm to 26 nm,and the Bessel beam axis is generated.The light intensity distribution is closer to the ideal distribution,and the influence of the dome angle of the deformable mirror on the beam quality is improved,which proves that increasing the number of deformable mirrior actuator rings can effectively improve the Bessel beam quality.In addition,Bessel beams were generated using 15°,30°,and 45°incident beams.The experimental results show that the generated Bessel beams are of good quality and are not affected by the incident angle of the beams.This article provides suggestions and basis for generating high-quality Bessel beams by anamorphic mirrors,which is beneficial to its application.(3)Filter technology is used to improve Bessel beam quality and perform beam shaping.In order to increase the stability of the Bessel beam intensity distribution based on the deformed mirror and generate an elliptical Bessel beam with a main spot,a filter consisting of a fan and a ring was designed.The ring filter performs filtering by focusing the plane beam,which can eliminate the influence caused by the dome shape of the deformed mirror,stabilize the change of the axial light intensity,and effectively improve the controllability of the light intensity distribution;the combined filtering of the fan shape and the ring shape The device can directly shape a circularly symmetric Bessel beam into an elliptical Bessel beam.The elliptical Bessel beam produced has a stable light intensity distribution,the axial light intensity FWHM reaches 247 mm,and maintains the "no diffraction" characteristic The ratio of the major and minor axes of the main lobe of the beam is about 1.72.The filter can effectively improve the beam performance based on the Bessel beam generated by the adaptive optical system. |
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