光弾性法における位相子モデル

I. Mindlin-Aben型方程式の旋光性

抄録

A formal mechanism of optical activity described by Mindlin-Aben type equations is clarified. On the basis of this result an approximate method for representing the behavior of polarized light in a photoelastic medium by “Piled Retarders Model (PRM) ” is investigated. PRM is defined as an optical system containing thin wave plates with various relative phase retardations, each of which is rotated with respect to the one preceding it through a definite angle. It is found that Aben's equations are represented as the limit of the equation B (z+Δz) =S (-φ) G (f₀Δz/2) S (φ) B (z) forΔz→0. Here, B is the complex vector of polarized light propagating along the z axis and S (-φ) G (f₀Δz/2) S (φ) represents a single wave plate having the thickness Δz, the retardation f₀Δz=C (σ₁-σ₂) Δz and the orientation φ at a point z in the medium, where σ_j and φ are the secondary principal stresses and the orientation of σ₁, respectively, and C is constant. This result enables us to regard an arbitrary optical path in the photoelastic medium as a system consisting of an infinite number of wave plates, each of which has the retardation f₀ (z) dz, the orientation φ (z) and the infinitesimal thickness dz at the point z, where f₀ (z) and φ (z) varies continuousluy along the path according to the stress distribution.