Design method for the structure of a gravitational wave detection telescope with low TTL noise.

As a critical payload of the gravitational wave detection interferometry system, the tilt-to-length (TTL) noise has a significant influence on the detection accuracy of the interferometry system. The non-geometric TTL (NG-TTL) noise, which is the main component of the TTL noise within the telescope, is closely related to the sensitive aberrations of the system's small pupil. Due to the different environments of the earth and space, structural deformations of the telescope can cause significantly unfavorable changes in the sensitive aberrations at the small pupil. And its negative influence must be considered carefully during the whole structural design phase of the gravitational wave telescope. In this paper, the theoretical model of the NG-TTL noise within the telescope based on the Fringe Zernike polynomials has been summarized. An evaluation function of the NG-TTL noise within the telescope was proposed. A desensitization design method for the high-stability structure of the gravitational wave telescope was developed. The results show that under the same disturbances, the NG-TTL noise within the telescope was reduced to 0.1 pm·Hz from 2 pm·Hz, taking the primary mirror (PM) as an example.