A vision-based robotic calibration system for the EAST motional Stark effect diagnostic

Precise calibration of Motional Stark Effect (MSE) diagnostic sightline is fundamental for reliable plasma current density measurements in EAST tokamak. This paper presents the development and experimental validation of a vision-based robotic system for automatic MSE calibration. The proposed system integrates a 6 degree-of-freedom industrial manipulator with computer vision techniques to achieve three key advancements: (1) automated measurement of sightline pose, (2) polarized light generation and alignment, and (3) synchronized acquisition of optical transmission system responses. The calibration robot system was validated by workspace simulation, test bench in laboratory and practical deployment for MSE calibration within the EAST vacuum vessel during the 2024 and 2025 experimental campaigns. Compared to traditional calibration methods (based on 2021 and 2023 campaign data), the proposed robotic calibration system demonstrates significantly improved performance, by reducing the average sightline pose measurement repeatability deviation from 12.1 mm to 2.0 mm.