title: Quantitative comparison of gradient index and refractive lenses.
abstract: We analyze the Seidel wavefront aberrations and spot sizes of gradient index (GRIN) singlet lenses with Δn≈1. We consider and compare curved and planar GRIN lenses with F-numbers of 5 and 1 against equivalent refractive lenses. We find that the planar GRIN lenses generally have larger spot sizes compared to their refractive lens equivalents at wide angles. This appears to be due to an inability to correct for coma by adjusting the refractive index gradient alone. We can correct for the coma by bending the GRIN lens. This results in a singlet lens with performance close to but not exceeding that of the equivalent refractive lens. We also examine the impact of anisotropy on the planar GRIN lenses. We find that fabricating the planar GRIN lenses from a uniaxial medium has the potential to improve the performance of the lenses.
authors.affiliation: Center for Metamaterials and Integrated Plasmonics and Department of Electrical and Computer Engineering, Duke University, P.O. Box 90291, Durham, North Carolina 27708, USA. vinh.nguyen@duke.edu
authors.forename: Vinh
authors.initials: V
authors.lastname: Nguyen
authors.forename: Stéphane
authors.initials: S
authors.lastname: Larouche
authors.forename: Nathan
authors.initials: N
authors.lastname: Landy
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Lee
authors.forename: David R
authors.initials: DR
authors.lastname: Smith