R.Degen: Micro actuators for precise positioning applications in vacuum

The Micro Harmonic Drive ® gear is now established in the precision machine market as an ideal solution for precise positioning applications. This gear is manufactured using a modified LIGA process, called Direct-LIG. This allows the cost-effective production of extremely precise metallic gear components. With a diameter of 10 mm or less and with a tooth module of 34 μm or less the Micro Harmonic Drive ® is the world’s smallest back-lash-free gear. It’s excellent repeatability of less than 10 seconds of arc is the basis for a variety of applications for machines in the semi-conductor industry, optical devices and medical equipment. Recently there is increasing demand for micro gears for applications in a vacuum. In the fields of semiconductor manufacturing, pharmaceuticals manufacturing and materials research there is a trend to place various process steps or analysis tasks into a high or ultra-high vacuum environment. This presents new and difficult problems to overcome for manufacturers of gears or actuators. To enable these products to be used in a vacuum environ-ment special or dry lubricants must be applied and also special mechanical design modifications must be made. Micromotion GmbH, the manufacturer of the Micro Harmonic Drive®, has undertaken a development project involving tribological coatings to allow the use of this gear in such applications. In this paper we will present the various steps necessary to allow the use of the gear in a vacuum and will also describe an application in a micro-polarimeter for use in synchrotron research