Vibration performance of isolated slab concepts in laboratory settings

The "isolated" or island foundation concept is commonly used at high-end imaging suites (SEM, TEM, SPM, NMR), with the goal of reducing vibration at sensitive instrumentation. The operating theory is that, by separating the foundation supporting the instrument from the rest of the building foundation, the transmission of vibrations from environmental, mechanical, and other local sources, will be reduced. But is this concept truly effective at reducing vibration transmission from all or any of these sources? And if so, are the benefits present over the entire frequency range of interest or only limited to a narrow range of frequencies? This paper discusses the vibration performance of the island foundation concept and presents field data collected in four different settings. Data from three national laboratories and a commercial science facility are used to illustrate the benefits and disadvantages of this concept, in both the vertical and horizontal directions, for environmental, mechanical, and other local sources.