How to design lens system

"Modern Optical Engineering", by Warren J. Smith (McGraw-Hill Education) gives a nice introduction on lens design and optics in general (with a lot of examples of lenses).

A more theoretical approach is in "Fundamental Optical Design", SPIE Press Monograph, by Michael J. Kidger, and "Intermediate Optical Design" from same author.

There is also a lot of information in the manual of the OSLO lens design program (cfr the free version: http://www.lambdares.com/downloads/index.phtml)