Wavefront pre-compensation for thermal deformations in a high power inner optical system

The phase aberration caused by thermal deformations in a high power inner optical system is simulated and the wavefront pre-compensation for correcting the aberration is studied experimentally. Choosing Strehl ratio (SR) and the root-mean-square (RMS) of distorted phase as the characteristic parameters, the beam quality of outgoing laser is calculated when the wavefront of incident laser is compensated. Based on the computed results, the laboratory experiment is designed to model the thermal deformations aberration and the correction process by using two Liquid Crystal on Silicon Spatial Light Modulators (LCoS-SLM). The negative influence of astigmatism and defocusing on laser beam quality in far field is obvious and the astigmatism induces the non-axisymmetrical divergence of intensity distribution. After wavefront pre-compensation the power in the bucket (PIB) value of outgoing laser beam is close to the flat wavefront laser source. Both simulated and experimental results indicate that the method of wavefront pre-compensation can greatly correct the aberrations caused from thermal deformation, and the laboratory experiment is a feasible method to modeling the inner optical system with phase aberration.