Constant radius blade spring suspended bench for vibration isolation

High-precision measurements are typically isolated from ground motion to reduce seismic noise interference. We introduce a passive, spring-suspended optics bench for use inside a tabletop vacuum tank. The isolator uses four initially flat cantilever blade springs, loaded to a constant radius of curvature, to attenuate vertical motion. This type of constant curvature blade spring has the advantage of minimizing horizontal-vertical cross coupling around its suspension resonance frequency compared to other blade springs. We use finite element modeling to optimize the geometry of the constant radius blade spring toward maximizing its vertical isolation. We validate our modeled constant curvature blade results using an experimental shaker table setup, with geophone sensing. Our suspension bench achieves a vertical attenuation bandwidth of 3-90 Hz with horizontal-vertical cross coupling below -50 dB in the frequency range of 7-90 Hz. Using our model, we found that the cross coupling of the constant curvature blade spring is outperformed at higher frequencies by a pre-bent blade spring, which is flat at its operating point.