Really powerful optical design software

I have just discovered a package called OSLO for design of optical systems including multiple lenses and reflectors. It is incredibly powerful, and the challenge will be to learn how to pilot it well enough to get any benefit from it. But the package has a downloadable LT version that is fully functional except limited to 10 surfaces.
Looks like it will simulate parabolic and elliptical reflectors and will export designs to CAD packages.