How to combine two CO2 laser beams?

[jlew]

Dear friends,

We would like to combine two CO2 laser (each 100W) placed one aside of the other to one beam. We were told that the laser beam has to be polarized.

We have the following questions:

1.Must the laser source be polarized by the laser producer? If the producer
can NOT provide the laser source polarized, can it be done in the optical
beam combining unit?
2.What optical components are needed to combine the two beams to one?
3.What is the difference between beam combiner as a mirror or as a cube?
What is better for this application?
4.Can someone draw for our better understanding the schematic beams
paths and the needed optics?
5.Can, theoretically two pairs of combined beams be combined again, forming
one beam (of 400W)?

Thanks in advance

Jacob

[Laser.Tech]

jlew,
If the lasers you are using are not sealed tubes, the easiest way to combine them for doubling the output power would be to 'merge' the two laser heads into one. Basically, you would remove the HR from the first laser and the OC from the 2nd laser. Place them end to end, and you have ONE laser with twice the power. The two heads could be placed side to side, using two 100% mirrors at 45 deg. to 'bend' the beam from head to head in the rear. This technique is commonly used in industrial lasers.

If your tubes are sealed, or if the above approach just isn't practical, things get considerably more complicated (and a LOT more expensive!). You would need both beams to be polarized (a dedicated optic each) and then merge them using a combiner/splitter (VERY high cost). This would give you one beam (so to speak, it would still be two beams just sharing the same path and not interfering with each other). However, you could only pull this trick once. You would not be able to 'mix-in' any more beams.

One last word, the cost of the optics would almost certainly exceed the cost of just buying a 200watt laser in the first place.

Laser.Tech

[KTP]

The Synrad 50 watt laser I have does exactly this. It has two 25 watt sealed metal tubes (rf excited) that are each polarized, and the output from both of them is combined with a ZnSe optic. It actually makes for a nice output beam profile, and if one tube fails, you still have a 25 watt laser :-)