Measurement of rotation angle variation using conjugate vortex beams

The measurement of rotation angle variations is crucial in advanced manufacturing and precision sciences. However, conventional optical methods are fundamentally restricted by the pixel size of camera arrays used to resolve spatial interference patterns. To address this limitation, we theoretically and experimentally demonstrate a pixel-independent measurement scheme based on matched filtering of conjugate vortex beams. This approach directly transforms rotation angle variations into periodic oscillations of the central intensity. Decoding is achieved simply by counting intensity extrema, eliminating the dependence on camera pixel resolution for angular decoding. The angular measurement sensitivity scales linearly with the topological charge, achieving tunable detection precision. Furthermore, we show that such this method still works for small off-axis scenarios, ensuring the robustness in practical applications. This research paves the way for the development of next-generation optical rotation sensors featuring high environmental immunity and reliable pixel-independent characteristics.