Use Ray optics simulation; freely available software package with Linux mint distribution. This is for simulation purpose (really exciting!)
In addition why do you use powerpoint for such drawings; why don't you use inkscape? Try inkscape, scribus, blender, freecad for drawing and modeling (freecad). All of these are freely available for all operating systems. From these you can export publication quality eps format figures.
I have found pstricks very convenient. You can find more information in the following document: ftp://ftp.yzu.edu.tw/CTAN/graphics/pstricks/contrib/pst-optexp/pst-optexp.pdf
There is a problem with the link. I attach the pdf file. To get an idea of the schemes that you can create, see Fig. 3 in the following article http://arxiv.org/pdf/1510.04397.pdf
Inkscape is a good tool to learn for vector graphics in general, and there are quite a few online tutorials, forums etc. I've made optical setup drawings as well as business cards in it. :)