Abstract
In this paper a finite-difference time-domain method is used to model and analyze the application of dynamic scanning in target detection and imaging by using an effective negative-refraction photonic crystal (NR-PC) flat lens. The results show that there is a transmission peak, with a value far greater than unity, resulting from the influence of mini-forbidden bands and resonance excitation effect at a resonance frequency of 0.3068(a/λ). Thus, the lightwave emitted from the point source will provide strong backscattered waves after being focused on the target by the NR-PC lens that greatly improves the refocusing resolution and imaging resolution of the backscattered wave. Furthermore, a comparison with a non-dynamic scanning scheme clearly demonstrates that the dynamic scanning scheme provides improved refocusing resolution. In conclusion, our investigation optimized the performance of a detection and imaging system, and provided the basis for converting an idealized LHM lens into a physically realizable NR-PC flat lens.
Highlights
In this paper a finite-difference time-domain method is used to model and analyze the application of dynamic scanning in target detection and imaging by using an effective negative-refraction photonic crystal (NR-photonic crystals (PC)) flat lens
Because the negative-refraction-index materials (NRIM) have negative permittivity and permeability, and the electric and magnetic field vectors form a left-handed set with the wave vector, such artificial materials are referred to as left handed materials (LHM)
By measuring the full width of the beam profile at 0.707-maximum as given in Figure 3, we find that the refocusing resolutions are approximately 0.3718λ and 1.59λ for ωp = 0.3068 (a/λ) and ωp = 0.2068 (a/λ)
Summary
0.5004λ 0.6014λ 0.6388λ dynamic scanning scheme, and the dashed curves depict the non-dynamic scanning scheme. When using the dynamic scanning scheme to detect a square target with side lengths of L = 1/6λ, L = 1/10λ and L = 1/30λ, there were approximately 6%, 24% and 25% improvements in the refocusing resolution, when compared to those when the non-dynamic scanning scheme was used. According to [7], for the LHM lens, the dynamic scanning scheme has a scanning resolution of 0.257λ when detecting a PEC cylinder target with a diameter of D = 1/6λ. The NR-PC flat lens and the LHM that the dynamic scanning scheme is superior to the nondynamic scanning scheme in target detection and imaging. The NR-PC flat lens and the LHM lens have approximately equal image accuracy when using the dynamic scanning scheme, and the refocusing resolution obtained by the detection of a cylinder target is greatly superior to that of a square target
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