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本文为非透明膜厚度提供一种新的测量方法。该方法测量简便,精度高,同时也适用于透明膜厚的测量。一、原理若用钠双线(λ_1=5889.963 A、λ_2=5895.930A)照射迈克尔逊干涉仪,在视场中可观察到干涉条纹的可见度随光程差的改变而发生“极大-极小-极大……”周期性变化。可以算出当二光路程差改变Δ=λ_1λ_2/(λ_2-λ_1)=988λ_1时,也就是迈克尔逊干涉仪的动镜M_1连续移动l=988/2λ_1距离时,干涉条纹的可见度整整发生一个周期变化,当动镜M_1连续移动21=2·988/2λ_1距离时,可见度发生二个周期的变化,当M_1连续移动kl=k·988/2λ_1距离时,条纹的可见度发生k个周期的变化。
This article provides a new measurement method for non-transparent film thickness. The method has the advantages of simple measurement and high precision, and is also suitable for the measurement of the transparent film thickness. First, the principle If the sodium double line (λ_1 = 5889.963 A, λ_2 = 5895.930A) exposure Michelson interferometer, observable in the field of view of the visibility of the interference fringes with the change of optical path length and the occurrence of “very large - very small - Great ... ”Cyclical changes. It can be calculated that the visibility of the interference fringes undergoes a periodic change when the distance difference of the two optical paths changes by Δ = λ_1λ_2 / (λ_2-λ_1) = 988λ_1, that is, when the moving mirror M_1 of the Michelson interferometer continuously moves by 1 = 988 / 2λ_1 When the moving mirror M_1 moves 21 = 2.988 / 2λ_1 continuously, the visibility changes two cycles. When M_1 moves continuously for kl = k · 988 / 2λ_1, the visibility of the stripe changes k cycles.