BulbCollector Forums
CLASSIFIED ADS => Wanted to Buy => Topic started by: ojim on November 15, 2000, 04:15:00 pm
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Hi Illuminady,
I wonder if this is the same lamp sold by Geo. Gates for scientific use. about 3cm by 10cm? These have been hard to find but I might be able to get duds.
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jim McConville
ojim@internetcds.com
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Hi Jim, welcome to the board.
I read your post and thought you might be able to tell me more about the following apparatus (see below). It uses the NA-1 Gates type sodium lamp. My question: was this purely a demonstration device to showcase this special lamp, or did this device have a more scientific / lab purpose? Any more comments about early sodium lamps welcome - I'm also looking for a good working lamp and demonstration unit like this. The photo below is from one that sold on ebay recently. I'm real curious to know what year production started and when production ceased.
(http://www.bulbcollector.com/photos/sodium.jpg)
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-Tim
BulbCollector.com (http://www.bulbcollector.com)
DewCollector.com (http://www.dewcollector.com)
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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.
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quote:
Originally posted by ojim:
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.
Thanks for the information Jim, I had no idea they were used in fine measurement work. You learn something new every day.....
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-Tim
BulbCollector.com (http://www.bulbcollector.com)
DewCollector.com (http://www.dewcollector.com)