Pictured on the left is a polarizer rotation stage for a precision atomic spectroscopy experiment in the UC Berkeley Physics department.
The rotation stage lies inside of a vacuum chamber to set the final polarization of a probe laser for measurement of the energy levels for an atomic beam of dysprosium. The polarizer was placed in the vacuum chamber so as to mitigate any errors in polarization due to the birefringence of the chamber window due to the pressure of the mounting plate.
The polarizer, not pictured, is affixed to the center aluminum ring in the middle of the large aluminum gear on the left. Not visible is the 90º gearbox which allows the shaft above the polarizer to control its position. All fasteners are titanium so as to avoid any magnetic perturbation, and all other materials are either aluminum, copper, or teflon.
The primary design was done by Arman Cingoz and Nathan Leefer, while I did much of the machining and assembly, in addition to a number of minor design alterations to improve functionality.
Additional photos below. Click the photos for captions.