Experimental Study on Performance of a Three-dimensional Rotating and Lifting Platform in an Imaging-lidar Calibration System

The three-dimensional (3D) Rotating and Lifting Platform (RLP) is the core component of imaging-lidar calibration system for Wide Field of View Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO). RLP mainly consists of three parts:the Programmable Logic Controller (PLC), the mechanical, and the standard zero subsystems, is designed to precisely control the beam pointing of the imaging-lidar system. A high-precision digital image processing method is adopted to investigate the performance of RLP. Our results reveal the rotating and lifting positional accuracies are 0.005° and 0.056 mm, respectively, while the corresponding repeatabilities are 0.003° and 0.075 mm, respectively. These outcomes fulfil the experimental requirements for the calibration system. The automatic cruise function of RLP not only minimizes the manual intervention but also improves both the reliability and efficiency for a remote control. The standard zero calibration function enables an effective observation of RLP's positional accuracy and implements a remote calibration in the case of a misalignment. As a result, we accomplish an accurately stable operation for our calibration system over a long period of time.