Development and Evaluation of a CAN-based Alignment System for Active Optics

In order to explore the primary mirror support of the Advanced Ground-based Solar Telescope (AST-G), this paper reported the development of the aligning system of an active optical mirror using CAN bus communication. Based on an active support system prototype, theoretical analysis of mirror kinematics with regard to the configuration of displacement actuators was firstly figured out. Then, a master node and three slave nodes were designed with STM32 to realize the distributed control of displacement actuators to actively align the mirror. Finally, we tested the performance of displacement actuator with CAN bus and the experimental verification of the mirror alignment. The results show that the control accuracy of the displacement actuator is better than 1 μm RMS, the rotations of the system around the x-axis and y-axis are better than 1″ RMS, and the piston error of the mirror is also better than 1 μm RMS. The research of the alignment system with CAN bus is an elementary technical preparation for future development of the primary mirror support system of the AST-G.