Proposal for Inverse-Phase Composite Zone Plate for Deeper Depth of Focus
Proposal for Inverse-Phase Composite Zone Plate for Deeper Depth of Focus
复制标题
用于更深景深的反相复合波带片的提案
DOI：
10.1017/s1431927618013739
复制
发表时间：
2018
影响因子：
2.8
通讯作者：
Takayama Yuki
中科院分区：
文献类型：
--
作者：
Kagoshima Yasushi;Takayama Yuki
波带片（ZPs），包括它们的衍生物，和全反射镜，促进了子100 nm的空间分辨率的实现，并使用X射线显微镜的实际样品的本地化分析的需求正在迅速增加。根据聚焦光学系统中的光学原理，聚焦光束尺寸越小，焦深（DoF）越浅。通常，光学中的衍射极限意味着空间分辨率（分辨率）的乘积。数值孔径（NA）不能小于波长，即λ × NA≥ λ。因为DoF也由NA（DoF = 1/NA 2）决定，所以不能同时获得更小的孔径和更深的DoF，这是衍射极限的另一个观点。这个限制限制了比DoF更厚的样品的分析，并且是使用X射线显微镜对实际样品进行高空间分辨率观察的瓶颈。本文提出了一种新的ZP，称为反相复合ZP（IP-CZP），并进行了研究，使自由度更深，空间分辨率几乎没有损坏。我们必须提到，分形ZP也被提出用于深聚焦[1]。
Zone plates (ZPs), including their derivations, and total reflection mirrors have facilitated the realization of sub-100-nm spatial resolution, and the demand for localized analysis of practical samples using X-ray microscopy is rapidly increasing. According to the optical principle in a focusing optical system, the smaller the focused beam size is, the shallower is the depth of focus (DoF). Usually, diffraction limit in optics means that the product of a spatial resolution (∆ res.) and the numerical aperture (NA) cannot be smaller than the wavelength, ie,∆ res.× NA≥ λ. Because DoF is also determined by NA (DoF∝ 1/NA2), smaller∆ res. and deeper DoF cannot be simultaneously attained, which is another viewpoint of the diffraction limit. This limit restricts the analysis of thicker samples than DoF and is a bottleneck in highspatial-resolution observation of practical samples using X-ray microscopy.We attempt to relax this limit using a wave-optical approach. In this paper, a novel type of ZP, called inverse-phase composite ZP (IP-CZP), is proposed and examined to make the DoF deeper with little vitiation in the spatial resolution. We must mention that a fractal ZP was also proposed for deep focus [1].