Work on Improving the Precision of Helium Laser Spectroscopy

Precision measurements of the fine structure of the helium 2P state provides a proving ground for various experimental techniques as well as a test of the bound state quantum electrodynamics of the electron-electron interaction.  Additional applications are to nuclear few-body physics and possible input to the fine structure constant determination. We update the study and status of:  (1) Circular polarized atomic beam preparation pumping, with 99.3% purity, achieved with a custom, miniature, annular NdFeB magnet assembly [1],  (2) Submicroradian stability and automated picomotor control of a coupled pair of fiber to free-space laser custom assemblies, and (3) In-house manufacture and filling of an iodine cell applied to an iodine stabilized HeNe 633 nm reference laser.  Data collection to further identify sources of uncertainty which limit precision will be examined.

1. Cameron, G.; Cuevas, J.; Pound, J., Jr.; Shiner, D. A Miniature Permanent Magnet Assembly with Localized and Uniform Field with an Application to Optical Pumping of Helium. Appl. Sci. 2021, 11, 8886. https://doi.org/10.3390/app11198886