Wavefront aberration evaluation of an off-axis two-mirror system through the optical-mechanical integration method based on dual quaternion

Off-axis reflective systems have become one of the preferred solutions for space optical payloads because of their high energy efficiency and small point spread function ellipticity. However, restricted by structural asymmetry, off-axis mirrors’ integrated assembly accuracy is always difficult. To achieve higher integrated precision during assembling, an optical-mechanical integration method based on dual quaternion (DQ) is proposed in this paper to evaluate the off-axis reflective system’s wave aberration. Firstly, static analysis of the off-axis reflective optomechanical system is carried out before and after loading installation error respectively. Then, based on the DQ, the rigid body displacements (RBDs) of the off-axis mirrors are calculated to ensure the accurate extraction of the node displacement residual caused by the mirror deformation. Furthermore, the Zernike coefficients of the off-axis mirrors’ surf, obtained through the vector height of the topological nodes, are used to estimate the system’s wavefront change. Finally, compared with the integrated analysis software Sigfit, the reliability of the wave aberration evaluation obtained by the optical-mechanical integration method based on DQ is verified. Simulation and experimental results show that the optical-mechanical integration method based on DQ provides a more accurate reference for predicting the integrated assembly precision of the off-axis reflective optomechanical system.