<title>Passive damping in optical tables using highly distributed inertial dampers</title>

Abstract

Optical tables are typically used in applications that require a very flat, rigid working surface. The grade ofthe optical table determines the amount of damping augmentation used to attenuate modal vibration. Discrete tuned mass dampers are a popular and effective damping method, however, their narrow effective bandwidth requires precise tuning to the table's resonant frequency. The present research deals with a damping method whereby a large number of small tuned dampers are distributed over the table's surface. In addition to the spatial distribution, the dampers are also distributed in frequency, providing energy dissipation over a wide frequency band. The wide effective bandwidth makes the distributed damping treatment extremely tolerant to variations in the table's dynamics. Test data is presented for a system of 349 dampers applied to a 243.8 cm x 121.9 cm x 20.3 cm optical table. The distributed damper attenuated both the first bending and the first torsion modes ofthe table, with a mass increase comparable to that realized with conventional discrete tuned dampers. The experimental results compared favorably to analytical predictions obtained using a full domain plate model.