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高中物理(必修本)第二册“薄膜干涉”中阐述了增透膜的厚度与相消干涉之间的关系:“当薄膜的厚度是入射光在薄膜中波长的1/4时,在薄膜的两个面上反射的光,路程差恰好等于半个波长,因而互相抵消。”根据这句话,有的人简单地外推为肥皂液薄膜或空气薄膜的厚度等于光在其中波长的1/4时,同样产生相消干涉,其实不然。 分析薄膜前后两个界面反射的光产生干涉时,必须考虑到光反射前后相位是否发生突变。实验证明:当光从光疏媒质射向光密媒质的分界面时,反射光波会发生180的位相突变(相当于半个波长的损失),但当光从光密媒质反射向光疏媒质时,却没有这种突变,至于透射光波,则不发生位相突变。如图1所示,设黑的
High school physics (required), Volume 2, Thin Film Interference describes the relationship between AR coating thickness and destructive interference: “When the thickness of the film is 1/4 of the wavelength of incident light in the film, the film The reflected light on the two surfaces is exactly equal to one-half wavelength and thus cancel each other out.” According to this sentence, some people simply extrapolate that the thickness of a soap film or air film is equal to the wavelength of light in which 1 At 4/4, destructive interference also occurs, which is not the case. When the light reflected by the two interfaces before and after the film is analyzed to interfere, whether or not the phase before and after light reflection changes must be considered. Experiments have shown that when the light is launched from the photolytic medium to the interface of the optically dense medium, the reflected light wave undergoes a phase change of 180 (corresponding to a half-wavelength loss), but when the light is reflected from the optically dense medium to the light-clearing medium However, there is no such mutation. As for transmitted light waves, no phase change occurs. As shown in Figure 1, set black