Study On High Power Solid-State Laser Beam Quality Diagnosis

Beam quality diagnosis is one of the important foundation contents in Laser research field. The requirement is different for different application purpose, so there is not a standard to evaluate beam quality and a method to measure beam parameter up to now. In the Inertial Confinement Fusion (ICF) filed, the laser facility works in the high intensity state, so nonlinear effects are obvious and damage risk of optical element is serious. The precise measurement is required for the large system with complicated influence factors, so the beam quality characterization must be researched specially and the measurement must find some non-related methods to verify the accuracy at the same time. This thesis focuses on two urgent problems: near field beam quality characterization and self certification of beam quality diagnostic system. The main results obtained here can be summarized as follows:1. Based on the mathematical statistics, two characterization models for near field beam quality have been built up: fluence distribution and power spectral density. Relationship between the two models is studied, and then a modulation, median frequency contrast RMS_v and characteristic frequency V_T were extracted as new near field evaluation parameter.2. Output near field of TIL from static state to 5GW/cm~were analyzed by the two near filed evaluation models. It is found that the spatial frequency method is more advantageous than the spatial domain method. The source of stable near field periodic modulation was found by characteristic frequency of it, then the reliability...