Commercial optical design software provide a very powerful tool for engineers at developing complex imaging and illumination systems. However, these programmes are not almighty: sometimes they miss models of certain optical elements/phenomena that are vital to solve demanding new challenges optical designers face day by day. By preparing macro or dll software extensions these shortcomings can be handled. The present Ph.D. dissertation treats three branches of modern optical design: integrated optics, beam shaping and hybrid diffractive/conventional optics. At all these fields the optical background knowledge is discussed in detail, then the developed models are presented together with application examples and verification tests. The new techniques in this book make the design process (analysis and synthesis) of certain optical devices more powerful (i.e. accurate, fast, convenient, providing additional degrees of freedom, etc.) in comparison with former methods. Due to its deep theoretical overview, this book can be a useful piece for engineers working at some of the fields discussed, or can help those who wish to implement software extensions to commercial optical design software.