Nondestructive analysis for HeNe lasers

Measurements of drop-out current and emission spectroscopy are used for nondestructive evaluation of gas pressure, purity, and He/Ne ratio in sealed HeNe lasers. With proper calibration, the measurement of three spectral lines (He, 501.6 nm and 487.5 nm, and Ne, 585.2 nm) allows the evaluation of both total pressure and He/Ne ratio. The ways in which these parameters and measurements techniques relate to the electrical operating characteristics of the laser are discussed.