Idea: Dual Purpose Fan

So had this idea recently - if you wanted to use a handheld laser up close to a surface to do things like etching free hand, the smoke from the burning surface would cloud up the lens and destroy it. That got me thinking the device wasn't very practical and there had to be a way to keep smoke and other residue off the lens. I then came up with an idea:

what if you had something similar to a weak air compressor or fan forcing a breeze of air across the surface of the lens, perhaps 2-5mm high, and you also had something like a long toothed bezel or other hard surface with gaps:

Example flashlight host
...so that you would have a surface to stop the lens from making contact, but also have gaps for the air to get out.

I also thought it would be kind of neat if the air flow could possibly serve the secondary purpose of blowing over the heat sink and/or circuitry to help cool down the whole thing.

Ideas?

If you search "laser air assist" in google, you might get more info. That's what it is called as used in laser engravers.

I think a protective window would be worth the losses, if beam cross-section is important. If polarized beam, perhaps a brewster or a well-coated anti-reflective window.

Of course, if you are already using the moving air to cool the heatsink, why not make it exit out the front too, as long as it's filtered first. Dust can't get in as easily if it has to fight air ;-) I'd say the lens protective function would just be a bonus, not something to rely on.

I would think that you'd need a protective window over the lens anyway. Would airborne particles abrade the lens if you had a constant fan going near it?