【摘要】 利用美国Spiricon公司生产的M2-200 Beam Propagation Analyzer(M2仪)测量了氙灯泵浦Nd:YAG的正支高斯非稳腔脉冲激光器的腔长变化对输出光束质量的影响。简要叙述了M2仪的使用方法和测量过程,介绍了几种评价光束质量的物理量。通过观测和分析,正支高斯非稳腔腔长的变化会影响输出光束的质量。实验中发现,当腔长为78 cm时光束质量最佳,此结果与理论值78.6cm很相近。误差主要来自两个方面:一是谐振腔内等效透镜主面位置测量不准确;二是腔内含有晶体棒时,腔长计算不精确。离焦比较大时光束质量明显变差,M2和发散角都很大;与腔镜的失谐灵敏度相比,高斯共焦非稳腔对腔长的失谐灵敏度小,失谐容忍度大。通过测量结果的对比得出,用M2因子评价光束质量是一个较好的选择。更多还原

【Abstract】 In these years,the solid state lasers have been developing very fast. The application of the solid state lasers requests the laser beam quality more and more better.So investigation of the effect on the output laser beam quality of the resonance cavity length changing is especially important.This paper investigates the effect on the output laser beam quality of the resonance cavity length changing of the Gaussian positive-branch confocal unstable resonators.The laser rod is Nd:YAG rod and pumped by Xenon lamp.The effect on the output laser beam quality of the resonance cavity length changing of the Gaussian positivebranch confocal unstable resonators has been observed.We have observed the effect by using of a M2-200 Beam Propagation Analyzer.The M2-200 Beam Propagation Analyzer is made by Spiricon company of USA.It can automatically measure the full angle divergences and M2 values and waist width and waist location and Rayleigh length in both the X and Y axes and X vs.Y astigmatism and X vs.Y asymmetry of the laser beam and display those parameters.The M2-200 Beam Propagation Analyzer is easy to use.But adjusting the optical train is very difficult before using it.The survey data is collected after our working some days.The survey data have shown that the changing of the resonance cavity length of the Gaussian confocal unstable resonator could affect the beam quality of laser output.When the resonance cavity length is 78cm,the full angle divergences and M2 values of the laser beam are the minimum in our experiments,the X vs.Y astigmatism value is 0.15,the X vs.Y asymmetry value is 1.01,that is to say,the laser beam quality is the best.The measurement result consists with calculating value,78.6cm.The error is due to two factors,one of which is that the position of the cardinal plane of equivalence lens is not exact and another is that the account of effective optical path is not precise when the laser passes through laser rod.Deviated the resonance cavity length from the one of confocal cavity in larger the laser beam quality would obviously be worse,that is,the full angle divergences and M2 values of the laser beam are larger.Compare with the misalignment sensitivity of resonance cavity mirrors,the Gaussian positive-branch confocal unstable resonators have the less adjust sensitivity for the resonance cavity length and there is larger tolerance for the resonance cavity length adjustment.In this report,the using means and the manipulative process of the M2 equipment are briefly described.A few of parameters to evaluate the laser beam quality are introduced.By contrast,the M2 factor is a better one than other factors for evaluating the laser beam quality.更多还原