DESIGN AND PERFORMANCE OF AN IMPROVED HOLLOW-CATHODE HE-CD+ LASER

A simple hollow cathode He-Cd+ laser which emits at least 100 mW multimode power at each of 441.6 and 533.7/537.8 nm from a 4 mm bore, 60 cm active length is described. Emphasis is given to the features needed to achieve discharge stability in this as well as other inert gas-metal vapour systems. Measurements showed that the axial extent of the negative glow associated with a single anode almost doubled when cadmium was introduced into a helium discharge. Although this suggests the possibility of some design simplification, it was found that little improvement could be achieved in practive because of the onset of discharge arcing when the current carried by a single anode reached 250 mA.