利用迈克尔逊干涉仪形成等间距同心圆状等厚干涉条纹

为了在教学过程加深对迈克尔逊干涉仪的理解,用锥顶角很大的圆锥形凸面镜或凹面镜替换平面反射镜,形成了明暗相间、等间距、同心圆状的等厚干涉条纹。针对两个镜子的不同组合,计算了该等厚干涉的条纹半径、条纹间距,并分析了条纹级次及条纹变动等特点。结果表明:对于条纹级次内高外低的等厚干涉图样,当膜变厚时,中心亮环往外冒;反之,膜变薄时,中心亮环往里吞,这与等倾干涉的条纹变动相似。而对于条纹级次内低外高的等厚干涉图样,当膜变厚时,中心亮环往里吞;反之,膜变薄时,中心亮环往外冒,这与等倾干涉的条纹变动相反。

Concentric-ring Fringes with Equal Fringe Spacing Formed by Equal Thickness Interference in Michelson Interferometer

In the interest of the thorough understanding of Michelson interferometer in teaching process, the alternately dark and bright concentric-ring fringes with an equal fringe spacing are formed by equal thickness interference in Michelson interferometer through the convex conic mirror or concave conic mirror with larger vertex angle taking place of the plane mirror. The radius, the fringe spacing, the order, and the change of fringe are analyzed in different cases. For the in-terference pattern with the higher order at the center, the bright-ring fringe emits from the center with the increase of air film thickness, while the bright-ring fringe shrinks inward with the decreasing of film thickness. This is similar to the change of fringes by equal inclination interference. For the interference pattern with the lower order at the center, the bright-ring fringe shrinks inward with the increase of air film thickness, while the bright-ring fringe emits from the center with the decreasing of film thickness. This is different from the change of fringes by equal inclination interference.