Figure 3
From: Controlling lightwave in Riemann space by merging geometrical optics with transformation optics
Schematic of bidirectional focusing. (a) Conventional parabolic mirror. (b) Conventional two-lens system. (c) Transmission-type focusing. (d) Reflection-type focusing. The black box is our device, which combines these two types of focusing and obtains bidirectional focusing. Note that beams from two opposite sides share the same focal point.
