Hazardous materials workaround


#1

I was wondering about laser cutting things we aren’t supposed to, like PVC. Is it possible to shine the laser through a thin sheet of glass without cutting or hurting the glass? And if that is possible, it seems like you might be able to make a glass case with high airflow through it to hold the hazardous object that you are cutting.

Which brings me to a more general question, how is it that the laser doesn’t cut its own glass lenses?


#2

The lens are made of something else. Standard glass is not transparent at the frequency of the laser.


#3

Zinc Selenide is a popular material for CO2 lenses/windows. It is transparent to light at 10.6um, where CO2 lasers operate. Germanium is also transparent at this wavelength, but is opaque at visible wavelengths. (Germanium is popular for thermal imaging lenses). I think germanium is less popular for CO2 laser operations due to a much lower damage threshold.

Here’s a link to a page with a nifty table of laser window materials for various wavelengths: https://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=1121


#4

Well, it isn’t just the windows, as many of you are well aware. Lasering anything with chlorine in it will ultimately create hydrochloric acid and corrode the bejesus out of any exposed surfaces. It would, over time, eat your laser.

Edit: I misread what you were talking about before. Even if it were physically sound and economically feasible (fwiw I don’t think either of those are true), you aren’t going to be able to set up any kind of clean room inside of the laser as there just isn’t enough working room - you’re better off saving up and getting a vinyl cutter and / or a CNC if this is super important, unfortunately.


#5

If you’ve bought the pro model you could create a very powerful and “protected” extraction system by using the pass through slot. I think the original idea would then work moderately well and you would probably wouldn’t need the glass.


#6

Thanks for that link! I had wondered about sapphire…
The cleaning article was educational. Hopefully the optic housing design of the forge will alleviate much of that maintenance.


#7

Right on, with regard to the HCl vapors. While ZnSe might very well be impervious to it (I don’t know if it is or not), AR coatings on the lenses and the dielectric stacks on any first-surface mirrors might also be susceptible. There’s also the mechanical components.

Where there’s a will, there’s most certainly a way. It’s just the eventual cost of that way that, um, gets in the way.


#8

I wasn’t sure either, so I did some research and found a PHOTONICS SPECTRA article talking about cleaning optics:

“Acidic solutions, however, should never be used on coated or uncoated zinc sulfide (ZnS) or zine selenide (ZnSe) components.”

So I guess that answers that.