The Research Of Nearfield Behavior Of The Output Beams From Axisymmetric Folded-Combined Cavity

At laser technology , in order to obtain the beam of high-power and high-qulity, beam combination is usually used for satisfying application's requirements. Maked use of beam combination , laser power will be achieved higher than single output of laser. The qulity of beam will be keeped with special method(i.e. phase control).Some technical schemes and features , by means of which the combination of laser beams can be achieved, have been analysed and compared in this thesis. Some theories in relation to beam combination have been explained.By means of the theory of beam combination, a kind of new cavity with axisymmetric folded-combined cavity have been presented. This cavity is that many discharge tubes of gas is tightly assembled and all of cavity share a output mirror . Used for this cavity, for the wave-length of 632.8 nm, the output power of He-Ne laser can attain the grade of hundred mw. He-Ne laser with the grade of hundred mw have clinical value at medical treatment. Two He-Ne lasers have been designed in experiment,one with simplest 2D axisymmetric folded-combined cavity that are composed of a concave-plano-concave folded cavity and a plano-concave cavity , and other with simplest 3D axisymmetric folded-combined cavity that are composed of two concave-plano-concave folded cavities and a plano-concave cavity.The nearfield behavior of output beams of this two type lasers have been studied in the theory. By means of the transformation matrix of obliquely incident beam, the nearfield behavior of He-Ne laser with 2D axisymmetric folded-combined cavity have been analysed and simulated. 1D symmetry distribution of output light intensity have been obtained. By means of a simplified model, the nearfield behavior of He-Ne laser with 3D axisymmetric folded-combined cavity have been analysed and simulated. 2Dsymmetry distribution of output light intensity have been obtained.All of two type analysis included that both two output beams from the same folded cavity have been coherent combined and the output beams form the different cavity have been noncohenert combined in combined-cavity.The study showed that not only the relative concentrate of light energy through coherent combination can be achieved,but also the dark region of light intensity, owing to coherent ,have been compensated by the contribution of output beam of plano-concave cavity at nearfield.The output of 3D combined-cavity have more dense light intensity and higher peak values than the 2D combined-cavity at nearfield. These results showed that the nearfield of output of the He-Ne laser with axisymmetric folded-combined cavity have extremely advantage to laser medical and the utilize of laser biology. The He-Ne laser with simplest 3D axisymmetric folded-combined cavity have been researched and manufactured by us in the experiment. The research showed that the adjustment precision generally was 20". At the same time, the experiment proved that this requirement was able to attain.