Large-aperture mirror testing technology

In the field of space optics, due to the wide application of large-aperture long-focal length optical system, aspheric mirror as an important component, its aperture is getting larger and larger, in order to save the emission cost, the lightweight degree of the optical element is also increased, due to the influence of gravity field, the mirror will be deformed, so it is of great significance to eliminate the gravity error through the ground test method, and accurately evaluate the on-orbit quality of the optical element. <br/><br/> Based on the orthogonality of different aberrations, a method combining the rotation and flip test and finite element simulation is proposed to measure the zero gravitational wavefront error of the mirror. The astigmatism is extracted by the rotation test of the mirror, and the assembly error and the support error are separated by the flip test of the mirror assembly, and the on-orbit quality of the mirror is obtained. Compare with the mirror shape of finite element analysis to form a closed loop. The φ1100mm high-lightweight mirror was tested by this method, and its 0 gravity wavefront was 0.014λ (@632.8nm), which was verified in orbit.