Operating Parameters of dc-Excited He-Ne Gas Lasers

Abstract

The output power of the 6328 Å helium‐neon gas laser has been investigated as a function of capillary diameter, total pressure, and He‐Ne partial pressure ratio at optimum dc discharge currents. The optimum value of p_Td (total pressure × capillary diameter) remains constant, and the scaling laws, power ∝ d, optimum current ∝ d are approximately satisfied for the four diameters investigated. The results suggest that optimum laser output is always achieved at the same value of electron mean energy and at a constant fractional ionization. This study permits a clearer understanding of the relationship between various helium‐neon discharge parameters and the 6328 Å laser output power, and by extrapolation allows the prediction of optimum gas fill for other capillary diameters. These results should also be useful in analyzing the effect of gas cleanup on tube life.