66 research outputs found
Towards the nano-world. Vibration measurements in and around the EL-TN and CT buildings and recommendations to minimize vibration levels in a new building, to be realized in 2006-2007, within the Masterplan of the U.T.
Evanescent Field Optical Microscopy: effects of polarization, tip shave and radiative wases
Vibration transfers to measure the performance of vibration isolated platforms on site using background noise excitation
This article demonstrates a quick and easy way of quantifying the performance of a vibration-isolated platform. We measure the vibration transfer from floor to table using background noise excitation from the floor. As no excitation device is needed, our setup only requires two identical sensors (in our case, low noise accelerometers), a data acquisition system, and processing software. Background noise excitation from the floor has the additional advantage that any non-linearity in the suspension system relevant to the actual vibration amplitudes will be taken into account. Measurement time is typically a few minutes, depending on the amount of background noise. The (coherent) transfer of the vibrations in the floor to the platform, as well as the (non-coherent) acoustical noise pick-up by the platform are measured. Since we use calibrated sensors, the absolute value of the vibration levels is established and can be expressed in vibration criterion curves. Transfer measurements are shown and discussed for two pneumatic isolated optical tables, a spring suspension system, and a simple foam suspension system
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