Surface shape detection methods for large radio telescopes

The surface accuracy of a radio telescope is directly related to its operational efficiency and detection sensitivity. This is crucial under high-frequency observation conditions, where surface shape errors need to be controlled to within 1/16 of the working wavelength. In addition, the primary reflector of large radio telescopes is subject to dynamic deformation, caused by factors such as gravity and thermal effects. This paper presents a method for detecting the surface shape of radio telescopes using radio interferometry techniques combined with active reflector adjustment technology. This enables accurate assessment and correction of surface errors, ensuring the electrical performance of the radio telescope. This study investigates the practical applications of high-precision measurement techniques, such as microwave holography, out-of-focus holography, and wavefront distortion methods at the Tianma 65 m radio telescope (TMRT). Furthermore, the study presents the construction method of gravity models at different elevation angles and demonstrates the efficacy of the active reflector model. The results of the measurements indicate that the application of these methods to the TMRT has led to a notable enhancement of the accuracy of the primary reflector and a substantial improvement in efficiency in the Q-band. Through a process of iterative measurements and adjustments, the surface shape error is ultimately reduced to 0.28 mm root mean square (RMS).