基于M-Z干涉的相干高斯光束远场干涉图样研究

Study of far-field interference pattern for coherent Gaussian beams based on Mach-Zehnder interferometer

为了使远场相干光斑分布及干涉图样的条纹间距和条纹对比度满足激光主动相干探测的要求,对基于马赫-曾德尔干涉原理的相干光发射装置发出的相干高斯光束在远场的扫描相干光场分布特性进行了分析,推导了高斯光束远场扫描相干光场的解析光强分布公式,得到了高斯光束远场扫描干涉图样。利用物理光学相关原理推导了远场的相干光光程差、干涉图样的条纹间距以及条纹对比度的表达式。数值仿真分析了马赫-曾德尔干涉光发射装置的分束镜旋转角度、探测距离和扫描角速度对远场相干光强分布特性的影响,得到了这几个物理量之间的定量关系。结果表明,远场扫描相干光强分布主要受到分束镜旋转角度、探测距离和发射装置扫描角速度等参量影响;干涉光发射装置的分束镜旋转角度同时影响远场接收屏上干涉图样的条纹间距及条纹对比度。该研究结果对实际探测中如何选取分束镜的旋转角、使其在满足条纹间距目标尺寸要求的前提下,适当调节旋转角度,获得尽可能大的条纹对比度是有帮助的。

In order to make the quality of fringe spacing and fringe visibility of interference pattern to meet the strict demands of active coherent laser detecting system of far distance,the distribution characteristics of coherent Gaussian beams based on Mach-Zehnder interferometer were analyzed. Optical intensity distribution of coherent Gaussian beams was deduced. Then interference pattern of scanning coherent Gaussian beams was gotten. The expressions of optical path difference, fringe spacing and fringe visibility based on Mach-Zehnder interferometer were derived by physical optics theory. The influences of rotation angle of beam splitter, detection distance and scanning speed on distribution characteristics of coherent light of far distance were analyzed and simulated numerically. As a result, the quantitative relation of rotation angle of beam splitter, detection distance and scanning speed was found. The results show that the distribution of coherent light of far distance is mainly controlled by rotation angle of beam splitter, detecting distance and scanning speed etc. Rotation angle of beam splitter in the interferometer has the influence on both fringe spacing and fringe visibility. The conclusion is helpful to choose the rotation angle in the experiment. Fringe spacing and fringe visibility should be taken into consideration simultaneously and the rotation angle of beam splitter is adjusted. It＇s useful to make the fringe visibility as large as possible.