OAM Imaging Method for Dielectric Targets Based on Near-Field Coupling

Vortex electromagnetic waves have unique modulation, enhancing imaging efficiency and resolution. However, most applications for orbital angular momentum (OAM) imaging focus on far field. An OAM imaging method for dielectric targets based on near-field coupling is developed. We use the vortex field generated by integer and fractional OAMs as the incident field, linearise the inverse scattering problem through the Born approximation, and solve it using the singular value decomposition method. The simulation results demonstrate that OAM beams of different orders can detect different imaging regions, and fractional OAM can effectively improve the robustness to noise by increasing the sampling.