Demonstration of vacuum strain effects on a light-collection lens used in optical polarimetry.

The precision by which an electron spin polarization measurement can be made using a noble-gas polarimeter depends directly on the accuracy of a light-polarization measurement. Since the electron-noble gas collisions occur in a vacuum chamber and the optical polarimeter is generally outside the chamber, this work examines the effect the vacuum window has on the perceived optical polarization. A model light source, lens system, and optical polarimeter are used that approximate the situation found in a typical atomic physics experiment. It was demonstrated that a pressure difference of 1 atm on a lens will alter the perceived polarization by as much as 0.05% with typical borosilicate (BK) lenses. This effect was demonstrated to scale with the thickness of the lens used and changes signs when the direction of the stress is reversed.