In case of these table support system the legs are used as air cambers..
The table is stocked in top of a club-shaped diaphragm mount.
The advantage of this bearing is the low-frequency tuning of the system which results in an effective isolation against floor concussion. The vertical characteristic frequency of this support is lower than 0,85 Hz. Assuming floor concussions with resonance above 8 Hz this corresponds to a degree of
insulation of more than 90%.The lateral characteristic of the bearing system is dependent from the set up. For the support systems RMT and DMT different level-control systems are optionally available.
Level Control System
A change in the load distribution on the table or a change in the load itself causes an optical table with air bearings to change its horizontal alignment and height. To maintain the table level at a constant height a level control system is required.
The level control system from OPTA precisely compensates for any load changes and keeps the table at its pre adjusted height. The self leveling repeatability amounts under optimum conditions to ±10 mm.
Throttle valves are used to control the leveling rate. The air pressure required lies below 6 bar.
The number of table support legs is determining the pneumatic control scheme. Usually four legs are used to support a table top. A three-point support is realized by a parallel connection of two air bearings. In case if more than four legs are required they have to be connected such that always three controllable groups are formed with one control valve per group. A pressure reducing valve at the control unit which is available as accessory can be used to adjust the required system pressure under different loads. Simultaneously the pressure of the three air bearings can be monitored.
The level control systems PVS and SVS from OPTA work without electronic components. As level monitoring devices pneumatic valves are used which mechanically detect the actual value of the system. The nominal standard will also be regulated by mechanically valves.