Well, I'm embarrased to say I know nothing about the dates of the Gates/GE Ma lamp. I started using them about 1960, I would guess they were 20-30 years old at that point. I think they were gone by 1985 or so.
The Na lamps are used variously. Machinists and engineers might use them to study surface topology in conjunction with an "optical flat", a slab of glass ground and polished to be extremely flat. They can easily be flat to 1/20 wave (1/20 of one wavelength of visible light,~ 600 nano meters.The monochromatic nature of the Na discharge gives rise to interference effects, oa the distance from the flat to the surface under study changes. See any good reference on precise mechanical measurements. Try an optics text.
A spectroscopist will use a Na lamp to align a Michealson or Fabry-Pirot interferometer.He may use the lamp to calibrate the wavelength scale of a spectrometer or monochrometer. The wave lenght and separation of the resonance doublet are well known (589 and 589.6).
If I recall, correctly, the lamp was used as a safelight for working with orthochromatic photographic film. I guess I could go on, but my memory is a bit rusty.
I will try to get some duds and perhaps a fixture or two.
