A beam pointing and tracking control method for rotating double-prism system based on virtual axis angular deviation strategy

Abstract

The rotating double-prism system, an emerging beam steering mechanism, achieves optical axis deflection through rotational modulation of two prisms, enabling high-precision angular positioning in free space. Due to the structural configuration of the two prisms arranged in series, the target tracking based on image feedback has strong nonlinear characteristics and coupling within the rotating double prism system. Consequently, the two prisms must be controlled in coordination to effectively deflect the reflected light. This paper introduces an innovative approach to adjusting the boresight by employing virtual axis angular deviation, grounded in the inverse ray tracing method. This method effectively separates the virtual pointing axis from the target visual axis. In contrast to traditional methods that rely only on the equivalent approximate information of image deviation for control, the proposed technique offers a more precise solution. In addition, the integration of a coupled proportional controller into the visual axis control method enables the system to stably track dynamic and static targets in real time. In the static target tracking experiment, the proposed method demonstrates effective convergence for targets at different positions in the working area. In the dynamic target tracking experiment, it successfully tracks targets moving at different speeds and along various trajectories. Compared with existing tracking methods, the proposed method has improved tracking performance.