Dear Reader, For an optical project having two LASER beams are being reflected by a mirror kept at a distance of 4 mtrs. These beams will be converged to a very fine spot using a lense. Before freezing upon the parameters like diamensions of mirror, focal length of a lense etc, I need to simulate this (2-D). Is there any free tool (on-line or downloadable) available? Tried googling, but in vain. Thanks in advance.