Influences of thermal deformation of cavity mirrors induced by high energy COIL to beam quality under the simulated real physical circumstances

摘要

The positive-branch confocal unstable resonator with inhomogeneous gain medium was studied for the normal used high energy COIL system. The fast changing process of the resonator's eigenmodes was coupled with the slow changing process of the thermal deformation of cavity mirrors. Influences of the thermal deformation of cavity mirrors to the output beam quality and transmission loss of high frequency components of high energy laser were computed. The simulations are done using program compiled by GLAD software. Effects of thermal distortion, misaligned of cavity mirrors and inhomogeneous distribution of gain medium were considered to simulate the real physical circumstances of laser cavity. The wavefront distribution and beam quality (including RMS of wavefront, power in the bucket, Strehl ratio, diffraction limit β, position of the beam spot center, spot size and intensity distribution in far-field) of the distorted output beam were studied. The conclusions of the simulation agree with the experimental results and the simulation results computed by ANSYS and FLUENT programs. This work would supply references of wavefront correction range to the adaptive optics system of interior alleyway.