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Vibration isolation system - The use of anti-vibration tables
2025-09-02 15:23:22
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1. Overview
Electron microscopes and other precision instruments have high requirements for environmental vibration. For instance, electron microscopes require low-frequency vibrations in the X, Y, and Z directions (0 to 30Hz) to be less than 6 micrometers. High-frequency vibrations above 30Hz are less than 12 microns.." Low-frequency vibrations below 20Hz have a significant interference impact on electron microscopes. If this index is exceeded, it will be difficult for an electron microscope to obtain an ideal image when taking photos at a high magnification (above 10,000 times).
When a conventional scanning electron microscope (SEM) is placed on a high floor of a building (above the second floor) or in a site with strong vibration (such as a subway nearby), observation and photography at a magnification of over 30,000 times cannot be carried out. And a vibration isolation system - an anti-vibration table - is used.
Field emission electron microscopy (FEM) requires observation and photography at hundreds of thousands of times magnification, which imposes even higher demands on vibration. Even if installed on the first floor, it still cannot meet the requirements. Generally, it is required to install an anti-vibration table.
Of course, the anti-vibration table used for electron microscopes is more suitable for other precision instruments. The AVI400 model of Swiss Table Stable Company is a vibration isolation pad with two separate units and is very convenient to install.
2. Principle
There are two types of vibration isolation tables: passive and active.
Passive types use rubber, metal springs, air springs, etc. Their shock absorption effect for low-frequency vibrations below 20Hz is very poor. In the range of 0 to 20Hz, they will increase the resonance of the SEM and are not adopted.
The active type uses a 3D detector to detect external vibrations transmitted in the 3D direction (X, Y, Z). The PID controller generates control signals of equal amplitude and opposite phase, and then the actuator generates internal vibrations of equal amplitude and opposite phase to counteract or weaken the external vibration interference.
3. Selection
The actuator - vibration isolation pad of Swiss Table Stable Company is two long strip modules. It is lightweight, small in size, easy to install, moderate in price, and has a large number of domestic users.
4. Practical effect
The customer's EVO MA 25 SEM is installed on the third floor, and photography above 10,000 times cannot be carried out. Since December 2012, the Swiss AVI-400 anti-vibration stage has been used, ensuring the normal operation of the electron microscope. Satisfactory images can also be obtained when taking photos at a magnification of 100,000 to 200,000 times. Please see the following photo
Before earthquake prevention
After shock absorption
