What lens to buy for burning?

i was looking at novalaser accessories and i want just a lens to attach to the end of mine to burn. but they have a lot. which one for burning? the concave, convex, meniscus or collimator?
please let me know thanks

You seem to be a bright fellow. Why not search in each kind of lens and see for yourself what they can do ?

contaminator. it pulls the beam together into a dot for burning i believe.

Tony --

It all depends on what you want to do. The easiest is to use a magnifier to get a burn at close range -- say 2 to 3" .....

A colluminator, using two lenses, works for longer distance but can be hard to focus.

Mike

I would suggest a convex (converging) lens with a focal length (The focal length is how far in front of the lens the light will cross) of 2-4" myself.

A convex (diverging) lens will spread the light out (as per its name) which would be bad.
A positive meniscus lens will act as a converging lens however I would stick with a convex lense.
A negative meniscus lens will cause the light to diverge.

A collimator will generally be a convex lens, however it will have a focal length on the scale of millimeters which will make it useless for burning (If you can even get the lens close enough to the object to burn, it will get covered in smoke/crap).

A magnifying glass will work fine as a cheap (read, very cheap) convex lens.

All of this information is just one wikipedia page away.

Tony;

You need a aspherical, AR coated, short focal length glass lens for the best power.

Here is a link to one that I think works very well,
for BluRay and OC Reds:

http://www.laserpointerforums.com/forums/YaBB.pl?num=1236386077

LarryDFW