Design of a Precise Axial Adjusting Mechanism with Three Guiding Flexures for Optical Element

The guiding flexure is generally used in the positioning mechanism for in-plane movement and nanometer level adjustment accuracy. In this paper, an axial adjusting mechanism for regulating optical element in ultra-precision optical system is designed utilizing the guiding flexures which are arranged in space so that the mechanism can obtain out of plane movement with high adjustment precision. The structure and working principle of the axial adjusting mechanism are described. The stiffness analysis model is established. The adjusting and guiding capabilities of the adjusting mechanism owing to the spatial arranged guiding flexures are analyzed by finite element analysis (FEA). And the relationships between the key dimensions of the guiding flexures and the characteristics of the adjusting mechanism are investigated. The results show that the compliance in Z-direction which characterizes the adjusting capability of the adjusting mechanism and the axial/lateral compliance ratio which characterizes the guiding capability are mainly influenced by the thickness and length of flexible hinges in the guiding flexure. Under the premise of the stress within 150 MPa, the compliance in Z-direction can reach 19.8 μm/N, and the axial/lateral compliance ratio can achieve about 170.