Negative-Stiffness Vibration Isolators Provide a Significant Improvement Over Air Tables in Vibration-Sensitive Environment

June 30, 2008
Although air tables have been around for the better part of a half-century, their usefulness as an efficient method for vibration isolation is now being seriously challenged by the more compact and effective Negative-Stiffness vibration isolators.

For almost forty years pneumatic vibration isolators have been the mainstay for stabilizing industrial and academia’s most critical micro-engineering instrumentation. But, just as technology has been steadily migrating from micro to nano, so has the need for more precise vibration isolation in microelectronics fabrication, industrial laser/optical systems and biological research. These so called “passive system” air tables are now being seriously challenged by the newer Negative-Stiffness vibration isolators. Negative-Stiffness isolation is rapidly gaining popularity in industrial and laboratory environments, and to no small degree because of its ability to effectively isolate vibration in diverse and challenging environments.

An isolator is used to solve a problem, and how bad the problem is determines the solution you need. Since the 1960’s air tables have been used for isolation. Basically cans of air, they are still the most popular isolators used. But, air tables with resonant frequencies at 2 to 2-1/2 Hz can typically only handle vibrations down to about 8 to 10 Hz, not quite low enough for optimum performance with modern nano-equipment. Also, greater isolation efficiencies are needed in the frequency ranges air isolators can handle.

For purposes of clarity in scanning probe microscopes and interferometers, air tables are an inefficient isolation solution. The air systems have been adequate up until a few years ago when better isolation was required.