Acoustical Testing

In the case of a scanning electron microscope, the majority of them have a built-in passive or active vibration cancellation system.  However that does not exclude the susceptibility of the SEM to the induced acoustically coupled vibration.  The sources of which are usually air-handlers in a clean room.  Plot A shows the acoustic noise specification that we have created for a particular kind of scanning electron microscope.   A large speaker was used as a driving mechanism to excite the tool at its resonant frequencies in each one third octave band.  Plot B shows the room reverberation after an impulse caused by popping of a balloon.  The exponential decay rate of the sound pressure is apparent.