Long distance CO2 collimation

[MindBender]

Hi Guys!

I'm new to this forum, but not new to lasers. I've been building high voltage supplies to power HeNe tubes long before most people knew about lasers. When playing with dental lasers (Nd:YAG, Er:YAG) over 10 years ago, I got fascinated with high power lasers. Unfortunately those were unaffordable at that time.

Nowadays you you can get a 40Watt CO2 tube on eBay for under $100, and including a power supply for roughly double that amount, so it's time to get playing. Yeah, I know, many people consider CO2 hardly to be a laser at all, because of it's poor qualities.

Now I wonder if it would be possible to get a CO2 beam collimated over a long distance, so we can still burn stuff at let's say 10 feet away. Or perhaps even 50 feet away. I don't want to focus over a lond distance (yet), but I do like to get divergence under control. There doesn't seem to be a wide variety of choice in lenses, I'm afraid.

Thanks in advance!

 

[Krutz]

Welcome to LPF!

As far as I know, only ZnSe optics are used with CO2. Besides that I see no difference to any other laser! Collimate with lens(es), use a forward or reverse telescope to tighten the beam and lose divergence, or vice versa.
For long distances a telescope to expand the beam quickly "pays off". Have a look around what others did with beam expanders (for visible wavelengths).. For using ZnSe optics, Mike (Hemlock_Mike) built a portable CO2 with expander.. Thread was "Star Wars" or similar..

Good luck, keep us updated!

Manuel

 

[LSRFAQ]

Welcome to LPF!

As far as I know, only ZnSe optics are used with CO2.

End quote.

lets modify that a bit shall we?

Germanium, Silicon, KCL all are used with CO2 and are often cheaper then ZnSe. If the OP really wants to upcollimate a CO@, he may find reflective optics with copper or gold coatings more to his liking, because they will be cheaper in the long run.

Steve

 

[Krutz]

thanks for the note, Steve.
Indeed, I have a slab of Germanium, which was used in a thermal camera. So yes, I remember, its (somewhat) transparent for far-IR.

cheers,

manuel

 

[HIMNL9]

I've found these pics, if they can be helpful, about transparence of different materials to IR.