A design of supporting structure for realizing large-field-of-view and high-resolution off-axis three-mirror optical system

This article explores a research on the application of off-axis optical imaging technology to biological imaging applications, from the aspects of optical system design, primary and tertiary mirror support structure design, system performance testing and evaluation, etc. On the basis of the three-mirror anti-astigmatism off-axis optical (TMA) system, a high-order aspheric surface is used to improve the imaging quality and minimize F-number (F#). The modulation transfer function of the optical system can attain 0.15@176 lp/mm, and in the full frequency range, near diffraction-limit imaging (high-resolution) performance can be achieved. A lightweight mirror chamber structure and a circular cantilever beam flexible hinge structure were designed. The statics and thermodynamics simulation analysis of the mirror support assembly is carried out. According to the analysis results, it can be seen that the structure has good stability and small surface changes, which can meet the requirements of actual use. A Zygo interferometer is used to assess the TMA system performance under the support. The test results show that the imaging resolution is 3.34 um, the imaging field of view is 151.1 mm x 22.16 mm, the system wave aberration edge field of view is about lambda/11.8, and the central field of view RMS is about lambda/13, which are both less than lambda/10. The test results show that the performance of the designed large-field high-resolution off-axis three-reflection imaging system meets the requirements of biological imaging.