Question about focus lenght lenses for CO2 laser

Hello all,

I’m coming to you experts with a question about focus lenses. I have a RF CO2 laser and I have the traditional 101.6mm and 63.5mm lenses. I would like to know what are the usecases and adventages to the shorter lenghts (I found 25.4mm, 38.1mm and 50.8mm).

Any idea ?

thx for the help
Have a nice one !

here is a link to a reasonably understandable explanation:

2 Likes

There are on-line calculators to compute the lens function. This is the basics.

RF co2 usually have a larger input beam to the lens than a glass tube. You might need to ask your vendor what the output beam size is for your source.

I wouldn’t have a use for a lens under 50 because it wouldn’t pass thru the nozzle. I like the nozzle because it protects the lens and is I great way to direct compressed air. Beyond the nozzle restrictions I can’t think of a reason why a 25mm lens would work better.

You probably will as time goes on. If lens length didn’t matter, you couldn’t buy such a wide variety of camera lenses or laser lenses. Same game…

Shortcoming of your system.

The actual tubes allow for different placement of the lenses by flipping it over.

:smiley_cat:

Jack, thanks for pointing out various ways to mount various length lens while still being able to use a nozzle. The original question was why would you use a lens that has a focal length of 25mm?

Smaller lens (focal length), smaller spot size gives you the ability for more detail. It also comes with a smaller dof.

So it really depends on what you are doing.

:smiley_cat:

The shorter focal length is great for detailed engravings. You can get a really nice small dot size.

Not great for cutting any thicker materials but if you are looking for the smallest possible resolution then 50mm and lower is great.

Thx for all the answers.