Help me identify this strange tube

[Calambres]

I've recently received a batch of NOS tubes. Between them there was this weird tube I cannot identify.
As you can see below, the only writing is 31878-D, hand written.
Any clues?

[mikeselectricstuff]

Looks like a discharge tube, used for UV/broadband or specific wavelengths depending on the gas fill and electrode materials. Typically used in spectrometers in chemical analysis gear, or maybe UV chart recorders.

[Calambres]

...Typically used in spectrometers in chemical analysis gear...

That makes sense knowing where it came from...

Thanks, mate! It is of no use to me but good to know nonetheless.

[Andy Watson]

I think Mike is on the money. With three wires coming from the base I think it might be a deuterium lamp - used for calibrating spectrometers and such like.

[Calambres]

Yep, I think you both are right. They're quite expensive too!

Thanks!

[PedroDaGr8]

I think Mike is on the money. With three wires coming from the base I think it might be a deuterium lamp - used for calibrating spectrometers and such like.

Not just for calibrating spectrometers, they are used as the UV source in almost every instrument where broad-spectrum UV sources are needed (i.e. UV-Vis Spectrophotometers, LC Absorbance detectors, Fluorimeters, etc.). As a chemist, I use at least one instrument with one of these every single day.

The design lacking a base and using spade connectors indicates a far older model instrument. Modern instruments will use either a "molex style" or proprietary connector. They also normally include a molded or metal base to ensure optimal alignment of the bulb.

See some examples of deuterium lamp types here:
http://www.spectrolamps.com.au/deuterium-lamps/

The most devious deuterium lamp I have seen is this one:

The connector is not custom but highly expensive, there is also an inline DRM chip in the wires inside of the connector.

[Calambres]

Not just for calibrating spectrometers, they are used as the UV source in almost every instrument where broad-spectrum UV sources are needed (i.e. UV-Vis Spectrophotometers, LC Absorbance detectors, Fluorimeters, etc.)...

As a matter of fact, I inherited this tube from a relative who owned a small factory that made, as well as many other instruments, Colorimeters and Fluorimeters.