Granite Isolator™ Theory of Operation

A vibration isolation device can be represented as a simple mass and spring system. This device is placed between the table top and the microscope.

The table top is always moving, and the goal is to prevent as much of this vibration as possible from reaching the microscope. We do this by the use of the vibration isolator which is schematically shown in the diagram. It consists of a mass, a spring that supports the mass, and damping that we describe below.

It is intuitive that the more mass (weight) one has in the vibration isolator, the less it will shake. It will simply tend to move less when the table top vibrates.

And the softer the spring on which the mass rests, the better the isolator will work. Damping is "friction" or a dashpot that absorbs energy as the table top vibrates. Damping is useful to reduce vibrations around the resonant frequency of the vibration isolator.

Granite is an ideal mass for a vibration isolator as it is heavy and has good stiffness and internal damping properties. It has been used for generations in anti-vibration tables and instrument bases. In addition, it can be attractive underneath the microscope.

The silicone gel supports used on the Granite Isolator make ideal "springs" as they are very compliant and have a high level of built-in damping. In addition, they are effective over a wide range of loading conditions. And they are long-lived, as units over 10 years old still retain their resilience and robustness. We have tested a number of soft elastomers, and this gel significantly outperformed all the rest due to its softness and high internal damping.

A potential problem with silicone is that it is one of the most difficult polymers to bond to. But we have developed a proprietary 12 step bonding process that bonds the silicone to the granite and the plastic with a strength that is higher than the silicone itself.