Displacements of large telescope sub-reflector based on 3D laser scanning

The sub-reflector of large-aperture radio telescopes is subject to gravitational deformation and displacement, posing challenges for accurate and rapid monitoring. In this study, a three-dimensional (3D) laser scanning technique was employed to monitor The sub-reflector of a 70-meter radio antenna. Spherical target markers were strategically placed within the feed source cabin to facilitate precise measurements. Rapid data acquisition and analysis enabled determination of the relative positional relationship between the centers of gravity of the target markers and that of The sub-reflector at various elevation angles. A corresponding fitting function was derived, and finite element simulations were conducted for comparison, demonstrating strong agreement between simulation and experimental results. This method was subsequently applied to correct sub-reflector displacements at different elevation angles, ensuring that the antenna gain and efficiency conformed to design specifications and operational requirements. Compared with conventional techniques, the proposed approach offers significantly improved measurement speed and data-processing efficiency.