Designing Precision Positioning For Vacuum Environments

The manufacture and calibration of UHV positioning systems is a complex task that sometimes pits design and maintenance considerations against the instrument’s technical performance. Accordingly, it is important to work with a partner with applicable experience.

HV typically is understood to have a pressure range of 10-3 to 10-7 mbar, while UHV has a pressure range of 10-7 to 10-12 mbar. A key difference between HV and UHV is that baking typically is absent from HV experimentation. The standard approach to achieving UHV is baking the test chamber/system to temperatures over 100 °C to increase the vapor pressure of water and any hydrocarbons present, which are then pumped out before cooling the chamber, leading to a higher vacuum.

Any positioning system designed for use in HV and especially in UHV must be robust, with a very low failure rate. The cleaning process for UHV stages is also critical; all parts, including any cabling, must be cleaned prior to assembly using an ultra-sonic cleaner, deionized water, various solvents, and a final cleanup solvent of pure ethanol.