多層膜の光学的特性

(I) 二層膜の場合

抄録

The contours of equal transmission of dielectric double layer and multilayer of alternate equal thickness are plotted on a diagram with δ₁ and δ₂ as ordinate and abscissa respectively, where δ₁ and δ₂ are the phase angles of constituent layers. Use of this diagram makes it possible to evaluate the spectral transmission of layers of any thickness. Analytical studies of maxima, minima, and saddle points of the contours of equal transmission are performed by the use of this diagram. Curves showing the relation between the thickness and refractive indices which gives R₂=0 are also plotted on δ₁-δ₂ plane with refractive index as a parameter, where R₂ is the amplitude reflectance of double layer.
From these curves, the relations among the solutions of λ/4-λ/4 antireflection film, thin highindex and thick-low index double-layer film, and achromatic film are investigated. There is no perfect antireflection film except these three solutions. Numerical calculations of the contours of equal transmission of double-layer antireflection film, beam splitter of double-layer film and alternating three-layer film are given.