Investigation of reproducibility of emission wavelength of helium-neon laser with external neon absorption cell (0.63 micrometers)

A stabilized LG-149-1 helium-neon laser with an external neon cell in a longitudinal magnetic field is investigated and found to provide wavelength reproducibility of 10 million, rather than the limiting values of 10 to the 8th power to 10 to the 9th power, due to shifts in the emission frequency. Frequency reproducibility is measured by a method utilizing a matrix of the frequency intervals formed by the published spread in the electrical parameters of the laser. The matrix provides a graphic representation of how changes in particular parameters influence shifts in frequency, and makes it possible to estimate the best-case situation. In the worse case, the frequency is combined, i.e., the reproducibility is determined by the sum of the diagonal elements of the matrix. Recommendations are given for ways of providing instrumento-instrument wavelength reproducibility of one to 10 the 8th power.