ABSTRACT
The cw He-Cd laser is perhaps the best known and most widely used metal vapour laser. It produces visible laser output in the blue at 441.6 nm [1] and ultraviolet output at 354.0 nm and 325.0 nm [2]. The blue transition produces the most power output [3] while the 354 nm transition is the weakest. A number of other lasers in the green and red portions of the spectrum have been observed in various types of He-Cd discharges. However, these lasers are not available in the commercial He-Cd laser that operates in a positive column type of dc discharge, similar to that of the He-Ne laser. Hence these other visible transitions will not be dealt with further in this discussion.
