Study Of The Design And Fabrication Of The MEMS-DMs

In order to meet the requirement of the expanding application of the adaptive optics system about the miniature of the corrector, the modeling, design and fabrication for novel deformable mirrors with low power consume and small volume are discussed detailedly based on the MEMS technology developed recently. The origin, current status and development trends of the MEMS and adaptive optics technology are investigated fully, and the research about the deformable mirror allover the world is summarized. Furthermore, the fabrication technique and the preparation and performance of the materials commonly used in MEMS are introduced in detail. A novel electrostatic actuated deformable mirror with continuous facet is designed and fabricated by using silicon bulk micromachining technology. Based on thin plate theory, the structure design, static deformation and dynamic response are analyzed, and the influence of the material property and structure parameters such as the thickness of the mirror plate on the mirror deformation and resonant frequency are also discussed. According to the transmitting theory, the light modulation ability is simulated for this mirror. Then some important processes in the fabrication such as wet etching and silicon-Pyrex anodic bonding are studied, meanwhile, a series of new methods are put forward to improve the device performance. Finally, a mirror with 30mm length and 49 actuators is developed successfully, and some basic characteristics about it are also tested. A segmented mirror with three movement modes is also studied. The double T-shape beam structure used for supporting mirror plate is put forwarded originatively. Based on its physical model, the equivalent spring constants of beam under deferent loading situations are deduced, as a result, the dimensions of some important components are optimized. According to the three actuating modes, the simplified models for mirror are constructed respectively, through which the static and dynamic electrostatic actuating characteristics and resonant frequency under freely vibration are analyzed, and the light modulation result about a 3×3 micro mirror array is also provided. A process flow including a half and two layer of polysilicon is drawn out, and a honeycomb like supporting post and multi-layer structure are designed to solve the surface corrugation caused by multi-step deposition and improve the quality of mirror surface. Finally, the static actuating performance of the fabricated mirror is measured and analyzed briefly.