Lenses - Theory?

[KPBadger]

Hi alll,

wondered if someone is able to clarify the following - (with respect to chinese glass tube laser) .

Focal length of lens:-
What are the relative pros/cons of longer/shorter focal length?
(i 'assume' longer focal length more suitable for cutting due to less tapering beam and longer focus zone ? )

Lens Coatings :-
some lenses are advertised for sale as uncoated, and suitable for any wavelength. Are these less efficient than lenses coated specifically for 10600?


Thanks for any assistance with this.

KPB

[bdring]

I have recently researched this and found a lot of good info at ...

http://www.parallax-tech.com/faq.htm

I compiled some of the equations into a calculator here ...

http://www.buildlog.net/cnc_laser/laser_calcs.htm

All of the parameters can be optimized, but usually at the expense of other parameters. I depends on what your priorities are...spot size, depth of field, etc. Check out the first link. It will probably answer all your questions.