Optics lens design sw recommendation

[pisoiu]

Hi,
Optics is not my strong point  . I understand basic principles but that's about it. However, I need to design a lens system and I have nobody I could ask to do that for me.
Basically I have a laser diode and I need to pull out from it a parallel beam of a certain dimension. For that, I need to use a convex lens or an assembly of concave and convex lens, because I have some size restraints.
Can anyone recommend me a free application for basic optics design in which I can enter some lens parameters and see how the light propagates? I do not need complex things, no coatings, I work with single wavelenght, etc. The goal is to get parameters of the lens I need, so I can send them to chinese manufacturers to make them.
Thanks.

[pisoiu]

Found: https://arachnoid.com/OpticalRayTracer/

[jmelson]

Basically I have a laser diode and I need to pull out from it a parallel beam of a certain dimension.

Generally, a sphere lens is used for this, almost touching the front of the laser module.  You can get 2mm and 3mm sphere lenses.

Jon