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An essential requirement of high-energy laser resonator configurations is the capability of efficiently extracting power in a near-diffraction limited beam. Mode discrimination as well as optical beam quality are often compromised as a result of temporarily varying refractive index perturbations within the gain medium, optical cavity misalignment, mirror figure errors resulting from manufacturing tolerances, and thermally induced mirror distortions. Various design approaches have emerged in recent years to optimize the far-field irradiance by utilizing different resonator concepts for the purpose of obtaining the best mode control and near-field beam quality. The different concepts utilize annular and compacted gain mediums, spatial filtering techniques, novel optical components and adaptive optics. This paper will describe recent results using intracavity adaptive optical techniques versus extracavity adaptive optical techniques. Experimental results will be provided which show the correction capability for controlled low order aberrations (tilt and astigmatism) commonly found in high energy lasers. A comparison of two optimization control techniques using a multidither zonal COAT system will be discussed describing the effects of hardware limitations and considerations on the performance of the system.© (1981) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. |
