English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We describe a design methodology for modifying the refractive index profileof graded-index optical instruments that incorporate singularities or zeros intheir refractive index. The process maintains the device performance whilstresulting in graded profiles that are all-dielectric, do not require materialswith unrealistic values, and that are impedance matched to the bounding medium.This is achieved by transmuting the singularities (or zeros) using theformalism of transformation optics, but with an additional boundary conditionrequiring the gradient of the co- ordinate transformation be continuous. Thisadditional boundary condition ensures that the device is impedance matched tothe bounding medium when the spatially varying permittivity and permeabilityprofiles are scaled to realizable values. We demonstrate the method in somedetail for an Eaton lens, before describing the profiles for an "invisibledisc" and "multipole" lenses.

Transmutation of singularities and zeros in graded index optical instruments: a methodology for designing practical devices