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In this paper, we have calculated the beam quality of practical unstable resonators under a variety of practical conditions. The effects of resonator geometrical parameters and misalignment were evaluated. Based on the Fresnel-Kirchhoff integral, the two-dimension phase and intensity have been calculated for practical positive branch unstable resonators. Using Second Order Moment (SOM) technique, 2 M factor for such resonator was estimated. The results show that the beam quality is very sensitive to misalignment of the resonator. We also show that 2 M factor increases with Fresnell number, while it decreases with magnification.

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The absorption of a polarized light in steep and dense plasmas with scale lengths of the order of light wavelength is calculated. The steep plasmas are simulated by EHYBRID code and assumed to be produced by interaction of ultra-short laser pulse (heating beam) with solid targets. The propagation of an electromagnetic wave in such plasmas is studied by matrix technique that usually is used for optical thin films. These plasmas are also assumed as stratified layers with different complex refractive index in each layer. Using matrix method, the Helmholtz wave equation was solved numerically, and the absorption of P and S polarized waves were calculated during the heating beam irradiation time. 521This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded