What's the difference between metal tube and RF tube?

[Kevin nixin]

Appreciate your insight.

[Richard Rumancik]

A "metal tube laser" uses a long metal tube (as opposed to glass) to contain the laser gas. The gas mixture contained inside and the tube is factory sealed. To make it lase, you need to excite the gas inside; with this type of laser an external RF (radio frequency) supply is used to generate energy that is absorbed by the gas inside the tube. An example of this type is the Synrad type lasers. So a Synrad tube is an RF excited metal tube laser.

Traditional glass tubes use a high voltage across the gas with electrodes inside on each end of the tube.

(There are other ways of exciting the laser gas - you need to add energy to it in some manner. In some types of lasers you could use an external light, flashlamp, another laser, microwaves, RF energy etc.) But I believe most glass co2 lasers use high voltage, not RF.

All of the laser tubes used in engraving systems are sealed (i.e. you do not replenish the gas inside the tube while in use.)

So I would say:

metal tube laser-> probably RF excited co2 laser; sealed metal tube
RF tube laser -> probably metal tube co2 laser (but could be glass)