论文标题
关于evanescent波的成像的基本局限
On the fundamental limitations of imaging with evanescent waves
论文作者
论文摘要
人们对使用渐射波来击败衍射极限的成像和聚焦方案引起了重大兴趣，例如那些使用负折射率材料或双曲线超材料的衍射极限。所有此类方案的基本问题是，成像系统和样品之间迅速衰减的渐态波，导致极弱的田间强度。使用对斑点大小的熵定义，该定义仍然定义为任意光束轮廓，我们在这种evaneScent衰减上得出了严格的界限。特别是，我们表明衰减长度仅为$ w /πe\大约0.12 w $，其中$ w $是焦平面中的斑点宽度，或$ \ sqrt {a} / 2 e \sqrtπ\ of 0.10 \ sqrt {a} $，其中$ a $是$ a $。因此，实用的逃生成像方案很可能仅限于小于或等于斑点宽度的焦距。
There has been significant interest in imaging and focusing schemes that use evanescent waves to beat the diffraction limit, such as those employing negative refractive index materials or hyperbolic metamaterials. The fundamental issue with all such schemes is that the evanescent waves quickly decay between the imaging system and sample, leading to extremely weak field strengths. Using an entropic definition of spot size which remains well defined for arbitrary beam profiles, we derive rigorous bounds on this evanescent decay. In particular, we show that the decay length is only $w / πe \approx 0.12 w$, where $w$ is the spot width in the focal plane, or $\sqrt{A} / 2 e \sqrtπ \approx 0.10 \sqrt{A}$, where $A$ is the spot area. Practical evanescent imaging schemes will thus most likely be limited to focal distances less than or equal to the spot width.
