Support Systems for Optical tables and Optical breadboards
In order to select the most appropriate support system for your optical table or breadboard, it is important to have cleared the requirements of the application:
- Sensibility required in your experiment to environmental vibrations
- Top weight (that is, the approximate weight of the set of components you are going to assembly onto the optical table)
- Spatial distribution on the weight placed onto the table (balanced/not balanced)
Here you will find a table summarizing the three types of support systems for optical tables available with OPTA:
Degree of isolation
How to change the height and level
Rigid non-isolating supports. Typical resonance frequency of 50 Hz.
Leveling screws to compensate the defects of the floor flatness.
Slighly sensitive to the vibrations
Supports with passive isolators. Partial vibration isolation (typical resonance frequency of 2.5-5 Hz). 4 types or isolators can be chosen depending on the load
Reinforced elastomeric shock absorbers between the optical tabletop and the support system
Pumping the rubber absorbers (occasionally)
Enough sensitive to the vibrations in environments with low vibration features
Supports with active self-leveling isolators (typical resonance frequency of 0.85 Hz). Complete isolation vibration.
The horizontal natural frequency is typically 1.5 Hz.
3 types of supports are offered depending on the load.
Leg body with compressed air + pneumatic valves
Releveling (need of air compressor machine)
Extremely sensitive applications (interferometry, ultra-short pulsed lasers…) in perturbed environments
*The Level-control System by default for this support system is SVS (Special Valve System). This mechanic system (no electronics) is suitable for high demanding applications and has adjustable leveling rate and special neumatic valves.
Additionally, there is available the high-tech Level-Control System Type ECS (Electronic Control System) for extremely sensible applications. This is a contact-free operating self-leveling system that offers optimized vibration isolation.
Here a detailed description of the three support systems for OPTA optical tables:
- LMT support system (Leveling Mount Table): support system without vibration isolation, that is, a rigid system (the table top is joint inflexible to the support system). Leveling screws which have a characteristic frequency above 10Hz are installed between the table legs and the table feet to compensate for unevenness in the laboratory floor.
There are indicated for those simple applications that do not need essentially isolation level.
- RMT support system (Rubber Mount Table): support system with low-frequency vibration isolation, that is, partial vibration isolated table top. The connection between the table top and the support system is realized with reinforced elastomeric shock absorbers (rubbers full of air). Characteristic frequency of these systems lies between 2.5 and 5 Hz, avoiding some kind of vibrations. For compensating the unevenness of the floor, regulating the optical table (according to the weight onto the table) or maintaining this support system re-leveled along the time, it will be necessary to pump the absorbers with a simple bicycle pump. This kind of support system is suitable for standard applications since apart from the partial vibration isolation, RMT support systems offer stability in both horizontal and vertical directions.
- DMT support system (Diaphragm Mount Table): for this self-leveling table support system, the legs are used as air cambers (air compressed pneumatics and a valve system) and the height and the flatness are automatically recovered. The table is stocked in top of a club-shaped diaphragm mount. Air compressor equipment (external device or a common air compressor line) is needed permanently to work with this system.
The advantage of this system is the low-frequency tuning of the system, which results in an effective isolation against floor concussion and other ambient perturbations. 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 vibration isolation system is dependent from the setup, but also high in any situations. Included level control system SVS by default.
In addition, the level control system from OPTA compensates for any load changes and keeps the table at its pre adjusted height.
Depending on the support system, the weight on top of the legs and also the special distribution of this weight, 4 or 6 lengths will be recommended and also double tie-bars. In addition, although all tables can be assembled by the customer, Iberoptics also offer the assembly service of the optical tables if required. A three-point support is realized by a parallel connection of two air bearings. In case of more than four legs were required, they have to be connected such that always three controllable groups are formed with one control valve per group.
Recommendation about optical table hight: With thin plates (33 – 50 cm) and small dimension tables, as well as, very little weight on top of the plate, we kindly ask you to have the support fixed onto the floor if you want more than 850-870 mm height.