Measurement for compensating for self-weight deformation error of large-aperture flat under vertical support

Abstract

Space optical components undergo surface deformation due to gravitational effects during ground assembly, introducing unnecessary gravity deformation errors, especially for large-aperture components. In this context, we propose a four-step rotation measurement method, in which the 600 mm diameter flat with the reflective surface vertically supported is rotated by 0°, 90°, 180°, and 270° in turn. The results are then reset and superimposed to obtain the surface shape result, thereby eliminating the gravity error. The experimental results show that the PV value is reduced by 52.23% and the RMS value is reduced by 46.42%, as verified by finite element simulation. This method compensates for the limitations of the traditional flipping method, significantly improving test efficiency, and is expected to overcome the technical challenges of precision measurement of large-aperture components in space.