Theoretical analysis of sensitivity-tunable total-internal-reflection heterodyne interferometer

This study presents a theoretical analysis of a sensitivity-tunable total-internal-reflection (TIR) interferometer. The interferometer consists of a heterodyne light source, an isosceles right-angle prism, and some polarization components. When a half-wave plate and two quarter-wave plates with proper azimuth angles are arranged in the tested arm, the final phase difference of the interference signal is associated with the azimuth angle of the transmission axis of the analyzer in the arm. Numerical calculations demonstrated that phase sensitivity and measuring range are controllable by tuning the azimuth angle of the analyzer. The feasibility of the measuring method was demonstrated by the experiment results. Our method of measurement has implicational merits of both common-path interferometry and heterodyne interferometry.

► The study develops a sensitivity-tunable total-internal-reflection interferometer.
► Phase sensitivity is controllable by tuning the azimuth angle of an analyzer.
► High stability and resolution due to its common-path setup and heterodyne detection.