Research on the methods of coordinate transfer of dual-laser-tracker system in the confined space of particle accelerator

Aiming at the practical application scenarios of particle accelerators and other large scientific devices, such as limited visibility and narrow space, this paper realises the collocation of the laser beam baselines of the two instruments through the target sphere magnetically attached to the measuring head of the laser tracking instrument, and constructs a solution model for the transfer of the coordinate system. Two methods are proposed: First, a gravity-based coordinate system is constructed to establish alignment with the horizontal plane, enabling instrument orientation solely through mutual observations without the use of common points. Second, under the unlevelled condition, the observation equations are constructed by calibrating or eliminating the initial position of the probe target sphere, and the unification of the coordinate system is achieved by combining the common point constraints in the middle field of view. This paper takes the connection between the particle accelerator experimental hall and the storage ring control network through the viewing hole as the application scenario, and conducts relevant experimental verification. The results show that at a distance of 8 m, the difference in rotation angle between the gravity coordinate system method and the traditional common point conversion is less than 0.004°, and the point root mean square (RMS) accuracy is 0.271 mm. The difference in the three-axis rotation angle under the unlevelled condition is less than 0.005°, and the point RMS is 0.259 mm and 0.224 mm, respectively. Both methods can achieve high accuracy coordinate transfer and have certain engineering application value.