Use of a diode laser to measure the polarization of an optically pumped ensemble of He(2 3S) atoms

A simple technique is described for determining the polarization of He(2 3S) atoms contained in an active discharge or afterglow. The polarization (and alignment) is obtained by measuring the attenuation of a circularly polarized probe beam provided by a 1.083 μm laser diode whose output frequency is scanned to allow separate measurements on the 2 3S1→2 3P0, 2 3S1→2 3P1, and 2 3S1→2 3P2 transitions.