Negative-stiffness vibration isolation
A new kind of vibration isolator, which is base on negative-stiffness theory, is made out for nano manufacture. In this paper, vibration isolation theory is mentioned to further explain negative-stiffness, and then Euler Columns and another negative-stiffness structure are introduced. Furthermore, the stiffness expression is figured out. Finally, a negative-stiffness vibration isolator is made to prove the theory and experiments also shows that its nature frequency is 0.45Hz and can isolate 79% of vibration at 1.9Hz and 97% at 4.9 Hz.
Negative-stiffness vibration isolation in laser and optical systems
As technology steadily migrates from micro to nano, so has the need grown for more precise vibration isolation in lasers and optical systems used in applications such as industrial testing, microelectronics fabrication, and biological research. Laser and optical systems, whether used in academic labs or industrial and manufacturing facilities, are very susceptible to vibrations from the environment. These instruments almost always require vibration isolation. When measuring a very few angstroms or nanometers of displacement, an absolutely stable surface must be maintained upon which to rest the instrument. Any vibration, coupled into the mechanical structure of the instrument, will cause vertical noise and fundamentally an inability to measure these kinds of high-resolution features.
New approach to vision-based BGA package inspection
Ball grid array (BGA) techniques have developed very fast due to the advantages of more I/O ports, small size, and so on. In this paper, a vision-based algorithm for BGA package inspection is proposed to accurately estimate center and diameters of solder-balls of BGA packages, so that defects of BGA packages, such as missing or extra balls, oversize or undersize balls, over-height or under-height balls, and pitch can be detected for ensuring the quality of BGA packages.