ABSTRACT
This chapter focuses on broadband lens designs enabled or inspired by quasi-conformal transformation optics (qTO) by exploring a wide variety of applications. It presents a series of broadband qTO-derived inhomogeneous metamaterials created from transforming the geometry of classical designs, including the Luneburg and Fresnel lenses. The qTO will be used to transform wavefronts and design a multibeam lens antenna. The chapter describes a systematic design procedure using qTO for anti-reflective coatings. It also discusses the effects of material dispersion on the performance of gradient-index (GRIN) lenses and presents a set of classical as well as qTO- inspired corrections. The simplest GRIN profile is one which possess a quadratic variation in index along the radial direction. The chapter also discusses the mathematical formulation of TO by introducing the concept of conformal coordinate transformation mapping. Conformal mappings use analytic complex functions and ensure angles and aspect ratios are preserved through coordinate transformation.
