Ultra-high Vacuum Application
Another example for the successful integration of the micro Harmonic Drive® gear is a new micro-polarimeter developed by BESSY in Berlin under the guidance of Dr. Andreas Gaupp.
This device is used to identify the concentration of elements featured in thin magnetic coatings, using, for example, the magneto-optical Kerr effect in the soft X-ray region (wavelength between 1 and 10 nm). This micro-polarimeter includes a complete sub-assembly comprising two vacuum-compatible micro-gearboxes used to accurately position the deflection mirror and the detector. In this application the control of the angle of incidence at the analyser mirror (a so-called multilayer with typically 150 double layers of, for example, chromium/scandium) within +/- 20 arc seconds is required. Both analyser and detector rotate relative to the light axis.
The micro-polarimeter is driven by a vacuum compatible stepping motor combined with two micro-gearboxes in order to achieve the required resolution and repeatability. The detector is driven using the same stepping motor and one micro-gearbox. Because the detector must rotate by double the angle of rotation of the analyser mirror two spur gear stages with different ratios are used to connect the motor to the micro-gearboxes. The picture shows the complete sub-assembly where the vacuum-compatible gearboxes are integrated to enable a precise positioning of the analyser mirror and detector.
|Dr. Andreas Gaupp, Physicist at BESSY||Synchrotron||Micro-Polarimeter|