Measurement Of Thermal Focal Length And Dynamic Compensation Of Fundamental Mode Resonator Of Thin-Disk Laser Based On Deformable Mirror

The thin-disk laser which is developed from diode-pumped solid state laser(DPSSL)has a high degree of thermal effect suppression due to its excellent structure design.However,with the increase of the pump power of the thin-disk laser,the thermal distortion caused by the thermal lensing effect cannot be ignored,playing an important part in restraining the output power and beam quality of the laser.It is very important to use spherical deformable mirror to measure the dynamic range of the thermal focal length of the thin-disk laser and to compensate the spherical part of the thermal distortion.Based on Kirchhoff thin plate theory,the bending of circular thin plate under uniform load is analyzed,and it is found that the deformation of the central region of the circular mirror can be regarded as a sphere.Then,simulation software COMSOL is used to simulate this model,and the spherical deformable mirror is actually manufacted.The test of the deformation characteristic of the mirror under different pressures were carried out.The experimental results of spherical deformation are obtained,and the relationship between curvature radius and pressure of spherical deformation is found,which lays the foundation for the measurement of thermal focal length and the design of dynamic resonator of the thin-disk laser based on the spherical deformed mirrorBased on the deformation range of the curvature radius of the spherical deformable mirror,a scheme whose width of the stability zone does not change and the boundary of the stability zone translates is designed to measure the thermal focal length of the thin-disk laser,so as to obtain a more accurate range of the thermal focal length of the thin-disk laser crystal.Then,based on the the thermal focal length range and dynamic cavity design technology,the matching relation between the thermal focal length and the deformation of spherical lens curvature radius in different injection power is given,making the laser's working point always works in the best position,which will lead to high beam quality of laser output at all pump power range.Finally,based on the spherical deformable mirror,the measurement of the thermal focal length of the thin-disk solid laser and the experimental study of the dynamic compensation technique of the fundamental mode resonator are carried out.The optical focal length of the thin-disk varing from 0.115(1/m)to0.189(1/m)under different pump powers is measured in the experiment.The dynamic compensation of the thermal focal length in the full pump range was realized by using a spherical deformed mirror.When the pump power is 55W,the beam quality factor M_x~2,M_y~2 decreases from 1.9544,1.9672 to 1.2052 and1.1153,respectively.