co2 lens info

[frafab]

hi! i'm looking for someone who can explain me the differences between the different type of lens for the co2 laser engraving, i've got a 200w laser...tnx.
someone can also tell me how i clean the lens...

[CNCadmin]

The Plano is for cutting and the meniscus for engraving as it produces the tightest spot size. The Plano is for cutting as the DOF is bigger than a meniscus lens.

[KTP]

By Plano, he means Plano/Convex. Sometimes you will also have a beam expander before your final focusing lens because the formula for spot size depends partly on the beam diameter entering the lens. But smaller spot size = smaller depth of field (area of the focused beam called the "beam waist" where the cut will be somewhat straight and the beam is highest power density).

If you actually mean the physical composition of the different lenses, I only know of 4 types you could *possibly* use.

ZnSe (zinc selenide) - orange color, passes visible light, usually coated with anti reflective layers, but could be uncoated and work

Germanium - silvery black color, doesn't pass visible light, needs coating because it has a high index of refraction and thus you will lose lots of power via reflection from the surfaces

Polished copper, gold parabolic mirror - some high powered lasers actually use this instead of a lens

Salt lens - does such a beast even exist? I would guess it *could* be possible

[frafab]

tnx for all, i'll ask for more if i need more specific info