Generalized Eaton Lens at Arbitrary Refraction Angles
  We extended the refraction angle of the Eaton lens into arbitrary angles. The refractive index of the Eaton lens is not analytical and can be obtained by numerical calculations only except in the case of the retroreflector. We introduced an approximation for the refractive index of the generalized Eaton lens. It is simple but very close to the exact values obtained from numerical calculations. 
Sang-Hoon Kim
physics.optics