牛顿环测定平凸透镜曲率半径.doc

牛顿环测定平凸透镜曲率半径
周芹 090404216 通信2班
关键字:等厚干涉,半波损失,奇数倍,偶数倍。
Newton ring determination flat convex
curvature radius
ZhouQin munication 2 class
Abstract: to understand the principle of such thick interference and actual application,
Learning to use Newton ring determination method of flat convex curvature radius, Master reading microscope use method, Learning to use through "gradual deduction method
processing data. Newton ring is produced with points amplitude method of interference, is the typical thickness interference interference phenomenon. Newton ring phenomenon is dark grain as the center, a series of hydrophobic within the dense alternate stripes of light and dark, according to optical path difference is half wavelength of odd number times or even times deduces the formula to calculate the evaluation of convex curvature radius.
Key word: thickness interference, half wave loss, an odd number of times, even
number of times.
引言:本实验采用牛顿环,读数显微镜,钠光灯等实验仪器。对折射率为常数的均匀薄膜,若能保持光线的入射角不变,从而折射角也保持不变,则光程差仅与膜的厚度有关。这
时等强度线即等光程差线的干涉条纹简单地相应于薄膜的等厚线,即每一条纹于薄膜上一个确定的厚度相对应。这种干涉称为等厚干涉,所产生的条纹称为等厚条纹。
正文:牛顿环是平板玻璃与球面间的空气薄膜上、下表面反射光干涉形成的等厚干涉花纹。
1、牛顿环的实验原理
原理图如下,垂直照射牛顿环仪上的单色光中任一光线,从接触面入射到曲面时被反射了一部分,另一部分穿过空气层射到平面镜上表面,在上表面又被反射回来,这两次反射回来的光束之间产生光程差2nd,又因为是从光疏介质向光密介质垂直反射的,要产生半波损失λ/2,所以,这两条反射光的总光程差为:
S=2nd+λ/2 (1-1)
其中,n=1为空气的折射率。
根据光的干涉条件,当光程差为半波长的整数倍时,形成亮条纹;当光程差为半波长的奇数倍时,形成暗条纹;