I have recently applied for a patent for a telescope, and used BEAM2 for the design work. I
believe I can put my hands on a number of Optics books I purchased during this work. If so, I
will send you references for establishing refractive indices, lens curvatures, etc. But as I recall
the early days of this work, the Beam2 package did an excellent job of serving up its own
system design, provided the user had his/her end objective in mind. If you are new to BEAM,
you might just try a refractive index of 1.6, set your object distance at your best guess--say one
cm--and your image distance at another distance of your choice, and then let BEAM do the
design work.
 
Perhaps this is too obvious, but I'm guessing you haven't used BEAM very much and haven't
experienced its excellent design capabilities.
 
I'll get back to you later today with the references if I can find them.
 
Good luck,
 
Peter Boulay
703-437-0307