Holographic meta-lenses for point-spread function engineering

光学成像系统的点扩散函数（即，其对点光源的响应）可以被设计成实现在基于折射透镜的常规成像系统中无法实现的成像模态。传统上，点扩散函数已经通过使用孔径和光学相位掩模来成形，从而导致诸如显微镜中的分辨率提高、对象可以保持聚焦的扩展景深以及移动对象的三维跟踪等功能。该计划将通过使用平面“元透镜”来探索工程点扩散函数的新范例，该平面“元透镜”是纳米结构薄膜，由于强烈的光-物质相互作用，能够局部改变光的振幅，相位和偏振。通过将超透镜和图像处理算法联合设计成一个集成的成像系统，将发明出功能强大的新成像模式。超透镜的平坦形状因子允许它们利用由集成电路工业开发的成熟平面制造技术来制造，并且受益于规模经济。光学成像组件和系统在这个程序中演示可能有机器视觉，生物医学成像和全息技术的各种应用的重要影响。该项目将培养研究生和本科生在纳米技术，材料科学和光子学之间的交叉点进行创新和深入的研究。该项目在哥伦比亚工程学院外联项目的支持下，将通过为来自不同背景的本科生提供夏季研究机会，扩大对科学和工程的参与。此外，该项目还将促进科学家和艺术家之间的合作，制作更易于公众接触的科学发现的吸引人和教育性插图。该项目将探索全息元透镜工程点扩散功能的新范例：单层或多层纳米结构薄膜可以提供相位，振幅，以及用于在大的波长和角度范围上对光学远场进行多变量操纵的光学近场的偏振。全息元透镜将由复杂的亚波长像素或“元原子”库组成。该项目将调查：结构色散工程以产生超原子，其提供最大可允许的相位色散，用于在宽光谱的连续波长上控制光;结构双折射和多组分超原子以提供光学相位、振幅和偏振的完全和独立控制;以及用于广角光学控制的多层超表面系统。研究工作将研究光学控制的基本限制，以建立一个光学参数（相位，振幅或在某一波长的光的偏振）可以由结构材料的单位体积控制的程度，并探索设计规则，以创建具有最小体积的结构材料，以独立和完全地控制多个光学参数。为了说明点扩散函数工程的新范例的前景，该项目将展示全息超透镜的几个例子，这些例子显示出超出基于折射组件和单层的传统成像系统能力的功能，相-该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的评估被认为值得支持。影响审查标准。

The point-spread function of an optical imaging system (that is, its response to a point light source) can be designed to achieve imaging modalities unattainable in conventional imaging systems based on refractive lenses. Conventionally, point-spread functions have been shaped by using apertures and optical phase masks, leading to functions such as improved resolution in microscopy, extended depth of field over which an object can stay in focus, and three-dimensional tracking of moving objects. The proposed program will explore a new paradigm of engineering point-spread functions by using flat “meta-lenses”, which are nano-structured thin films that are able to locally change the amplitude, phase, and polarization of light due to strong light-mater interactions. Powerful new imaging modalities will be invented by jointly designing meta-lenses and image processing algorithm as an integrated imaging system. The flat form factor of meta-lenses allows them to be fabricated with mature planar fabrication technologies developed by the integrated circuit industry and benefit from economies of scale. Optical imaging components and systems demonstrated in this program may have important implications for a variety of applications in machine vision, biomedical imaging, and holographic technology. The project will train graduate and undergraduate students to carry out innovative and in-depth research at the intersection between nanotechnology, materials sciences, and photonics. The project, with the support of Columbia Engineering School’s Outreach Program, will broaden participation in science and engineering by providing summer research opportunities to undergraduate students from diverse backgrounds. In addition, the project will promote a collaborative effort between scientists and artists in producing engaging and educational illustrations of scientific discoveries that are more accessible to the general public.The project will explore a new paradigm of engineering point-spread functions by holographic meta-lenses: single or multi-layered nano-structured thin films that can provide complete, independent, and sub-wavelength control of the phase, amplitude, and polarization of optical near-field for multivariate manipulation of optical far-field over a large wavelength and angular range. The holographic meta-lenses will be composed of a library of complex and sub-wavelength pixels or “meta-atoms”. The project will investigate: the structural dispersion engineering to create meta-atoms that provide the maximum allowable phase dispersion for controlling light over a continuous wavelength of a broad spectrum; the structurally birefringent and multi-component meta-atoms to provide complete and independent control of optical phase, amplitude, and polarization; and the multi-layered metasurface systems for wide-angle optical control. The research work will study fundamental limitations of optical control to establish the degree to which one optical parameter (phase, amplitude, or polarization of light at a certain wavelength) can be controlled by a unit volume of a structured material and to explore the design rules for creating a structured material with minimal volume to control multiple optical parameters independently and completely. To illustrate the promise of the new paradigm of point-spread function engineering, the project will demonstrate a few examples of holographic meta-lenses showing functions that are beyond the capabilities of conventional imaging systems based on refractive components and single-layer, phase-only metasurfaces.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.