1995 年 15 巻 1-2 号 p. 61-65
Retardations of po1ymer films have been obtained by Senarmont compensator. Its method is used only for monochromatic light, because of dependence of its quater wave plate on wave length. In the present study, retardations of films can be obtained using the composite quater wave plate for all visible lights.
Relation between retardation Δ and optical path difference J of a sample is represented by a equation of
Δ=J·2π/λ,
where λ is optical wave length. On a graph of Δ vs 1/λ, the equation indicats a straight line which passes the origin and its slope is 2πJ.
If measured points for several monochromatic lights are plotted on the graph and a fitted line is calculated, we can obtain the absolute retardation of the test piece from its line.