3-DOF decoupled magnetic platform for optical low-frequency vibration isolation

Abstract

Optical instruments, such as atomic force microscopes (AFM), are susceptible to interference from external vibrations, which can diminish imaging clarity and hinder optimal performance. A three-degree-of-freedom (3-DOF) decoupled magnetic platform (DMP) is proposed for optical low-frequency vibration isolation. The specially developed platform attains vibration decoupling through an orthogonal structural design and utilizes six identical vibration isolation units that are specially configured to achieve low dynamic stiffness and significantly low-frequency vibration isolation performance in both horizontal and vertical directions simultaneously. Different from the traditional realization of positive and negative stiffness combination, the novel isolation unit is designed using the constant magnetic force, which is generated from the magnetic field distortion. This implementation is revealed through magnetic field analysis and verified via static calibration. The dynamic model is established by considering viscous damping and dry friction, and the Runge-Kutta Method is applied to calculate the vibration response. Theoretical analyses are conducted to guide the design of the DMP and predict dynamic responses under different structural parameters, damping settings, and excitation conditions. Experiments are implemented to demonstrate the vibration isolation performance of the prototype. The result reveals the different effects of viscous damping and dry friction and demonstrates that the developed DMP has a broad frequency decoupled vibration isolation capability. The magnetic platform achieved by reusing the newly designed quasi-zero stiffness (QZS) unit provides a new option for optical vibration isolation, with the advantages of a large stroke and strong vibration decoupling.