| Summary: | 碩士 === 國立彰化師範大學 === 機電工程學系 === 99 === In this thesis, based on total-internal reflection (TIR), a phase sensitivity-tunable optical sensor was designed for measuring concentration variation of a liquid. The sensor consists of a heterodyne light source, a Mach-Zehnder interferometer, an isosceles right-angle prism, a compensator, half- wave plates, and analyzers. When the azimuth angle of the compensator is chosen properly, the final phase difference relative to the concentration of the two interference signals is associated with the azimuth angles of the fast axes of the half-wave plates, thus creating the controllable phase sensitivity. Numerical analysis demonstrates that the high phase measuring sensitivity and the small measuring range, and the low phase measuring sensitivity and the wide measuring range can be performed by selecting the suitable azimuth angles of the half-wave plates in the concentration variation measurement. The feasibility of the method was demonstrated by the experiment results. The sensitivity of 214～102390 degree/RIU, and the measurement resolution of ～ RIU, can be achieved.
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