Obtaining the Wavefront Aberrations of Passive Positive-Branch Unstable Resonators by Use of H-S Sensor

The effect of intracavity aberrated perturbation on output mode structure properties of passive confocal unstable resonator is been experimentally researched by adopting Hartmann-Shack (H-S) wavefront sensor and Zernike modal wavefront reconstruction on the basis of numerical simulation. The results show that intracavity tilt perturbation notablely affects outcoupled intensity distribution, and will also increase some high-order aberrations of beam phase properties. However, low-order Zernike tilt aberration is the main component when phase-tilted perturbation is introduced into the resonator. Defocus, astigmatism and coma aberration will all be brought, and also such high-order aberration included in wavefront will directly degrade output beam quality. When adaptive optical elements such as deformable mirrors are adopted for intracavity aberration correction, the correction of tilt aberration should be considered firstly.