High-precision displacement measurement method based on the interference of conjugate rotationally symmetric power-exponent phase vortex beams.

Existing vortex beam interferometric measurement methods are constrained by the linear spiral phase of conventional vortex beams, resulting in a fixed linear relationship between displacement and rotation angle, which limits further improvement of measurement accuracy. In this paper, rotationally symmetric power-exponent phase vortex beams are introduced. Based on their nonlinear phase distribution, a nonlinear correlation between displacement and rotation angle is established, and angular inhomogeneous modulation of light intensity is realized to amplify the rotation angle within a specific interval. By tuning only the power exponent, the proposed method achieves angular amplification without increasing optical system complexity, and significantly improves the micro-displacement measurement accuracy and system stability compared with traditional vortex interferometry.