Structural Design and Performance Analysis of Laser Transmitting Telescope for Space Gravitational Wave Detection

Abstract

The spaceborne laser emission telescope is a core and critical component of the space gravitational wave detection system.Compared with ground-based telescopes, the on-orbit space environment is more complex and harsh, presenting higher technical challenges for the design of the optical system and structure - both optical design and structural design face considerable difficulties. To meet the requirements of space gravitational wave detection, this paper designs a laser emission telescope based on an off-axis four-mirror configuration, with a capture field of view of 300{\mu}rad, an optical transmission efficiency of 86.3%, and an optical path stability index of TTL<0.025 nm/{\mu}rad. During the design process, based on existing theories and engineering experience, the primary mirror thickness optimization and lightweight structural design were completed, and a flexible support scheme was adopted to achieve a primary mirror surface figure accuracy of 9.42 nm; the total mass of the entire telescope (excluding mirrors) is only 3.845 kg. Multi-dimensional finite element analysis was conducted on the telescope under actual working conditions: the strength of the telescope's support materials was verified under self-weight and 10G gravity loads; after removing the rigid body displacement of the mirrors using Zernike polynomials, the surface deformation of the primary mirror was controlled within 1/30 wavelength. In the thermal stability analysis, the structural deformation of the telescope under a temperature change of 100 degree celsius was simulated, and key indicators such as eccentricity and tilt between the mirrors all meet the optical design requirements. In the modal analysis, the first-order natural frequency of the telescope reaches 200 Hz under both self-weight and weightless conditions, demonstrating excellent dynamic stability.