Obtaining Phase Properties of a Passive Laser Unstable Resonators by Processing the Image of Beam Facula Matrix

The effect of intracavity aberrated perturbation on output mode properties of a confocal unstable resonator is been experimentally researched by adopting H-S wavefront sensor and Zernike modal wavefront reconstruction. By processing the image of beam facula matrix, wavefront phase properties, Zernike aberrations, PV and RMS error, distribution of circle energy can all be acquired, so beam phase distribution can be known fully. 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 they will directly degrade output beam quality. When adaptive optical elements such as deformable mirrors are adopted for intracavity aberration correction, the correction of phase-tilted aberration should be first considered.