光源的相干性对牛顿环的影响

THE INFLUENCES OF LIGHT SOURCE COHERENCE FOR NEWTON'S RINGS

本文以普通光源和激光为例,探讨了光源的相干性对牛顿环干涉现象的影响。对于非相干光源,研究了单色性对相干长度的影响,指出仅有空气夹层上下表面的反射光会在平凸透镜顶点附近凸面内侧贴近凸面的区域形成一套干涉条纹。对于相干光源,利用斯托克斯定律推导了各表面反射光之间干涉条纹的可见度,进而分析了多套干涉条纹的叠加效果。

Taking ordinary light source and laser as examples, the influences of light source coherence on Newton＇s rings are discussed in this paper. For the incoherent light source, the effects of monochromaticity on coherence length are studied. It is found that only one set of interference fringes distribute nearby the vertex of the concave mirror, locating inside and next to the concave, which are formed by the air interlayer＇s reflected lights. For the coherent light source, the visibilities of the interference fringes formed by any two surfaces＇ reflected lights are derived by using the Stokes＇ law. Then the overlay of many sets of interference fringes is analyzed.