MRI: Development of a Holographic Nanoscale Optics Instrument

MRI：全息纳米级光学仪器的开发

• 批准号: 1429437
• 负责人: Thomas Bifano
• 金额: $ 38.39万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-15 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1429437&HistoricalAwards=false
• 关键词: MRI; Development; Holographic; Nanoscale; Optics

Non-technicalOptical (or light) microscopy is arguably one of the most successful techniques for the non-invasive examination of the microscopic world ever created. Robert Hooke coined the term "cells" to describe the substructure of cork he first observed through a microscope in the 17th century. Over the past century a variety of sophisticated methods have been developed that today provide the ability to observe migrating cells, examine the distribution of subcellular structures, map the expression of genes, or form "chemical images" coded according to the molecular structure of the sample. Despite its immense success, optical microscopy is fundamentally limited in its ability to resolve features less than a few hundred nanometers. Specifically, the diffraction limit causes light from points in an object to spread out as it propagates through a lens, thereby blurring images as they are magnified. Near-field microscopy overcomes these limitations by placing an optical probe a few tens of nanometers away from the object and sampling the emitted or scattered light before it experiences diffraction. Boston University researchers are building a versatile near-field microscope providing local and regional users with access to optical resolution on the order of 10 nanometers. The instrument is enabling a range of important research thrusts including (i) studies of protein folding behavior that can shed light on conditions such as Alzheimer's; (ii) the development of new materials for laser sources; (iii) methods for engineering the properties of single atomic thick layers like graphene for next-generation electronics and; (iv) methods for controlling the flow of light on nanometer length scales, important for new optical sensors and communications technologies. The BU project is also engaging women and underrepresented minority undergraduate students in cutting-edge research. Since the ability to "see" objects at the nanoscale can be a powerful motivator for a young mind, the team is working with BU's Upward Bound Math Science 7-week residency college prep program for urban high school students. Every Wednesday in the summer, students perform nanotechnology hands-on experiments and use the new microscope to observe the nano-world. Technical DescriptionOptical microscopy is arguably one of the most successful techniques for non-invasive examination of the microscopic world ever created, but is fundamentally limited to length scales of 100 nm or more by the diffraction limit. Near-field microscopy overcomes this by placing a source or probe into the near optical field of a sample to couple the non-propagating or evanescent modes into far-field propagating modes for collection. While there are 5 or 6 companies that sell near-field microscopes, all are limited in capability. Boston University researchers are building a versatile holographic nanoscale optics instrument integrated into an atomic force microscope, combining near-field spectroscopies of elastic scattering, Raman and fluorescence over a wide wavelength range. The instrument operates in both transmission and back-scattering geometries, and includes interferometry for phase-resolved near-field imaging to map 3D field response, providing the flexibility and dexterity that are critical to advance complex research problems. The instrument enables researchers at BU and regional universities to investigate nanoscale optical phenomena in plasmonics, biophysics, and graphene and other two-dimensional (2D) crystal membrane physics. Plasmonic studies are exploring hot spots, local density of states and in particular, phase singularities predicted to occur at the interface between metal and dielectric components. In strain engineered 2D crystals of graphene, MoS2 and hBN, researchers at BU are exploring atomic-scale friction and the exciting possibility of mapping strain-induced pseudo-magnetic fields. In studies of Germanium semiconductor nanomembranes, local optical response can confirm and help engineer nano-devices with direct bandgaps. And in biophysics, long-wavelength tip-enhanced near-field microscopy can provide unprecedented images of intrinsic vibrational modes capable of sub-cellular classification and local presence of important proteins.

非技术光学（或光）显微镜可以说是有史以来最成功的非侵入性检查微观世界的技术之一。罗伯特·胡克在世纪创造了“细胞”一词来描述他第一次通过显微镜观察到的软木的亚结构。在过去的世纪中，已经开发了各种复杂的方法，这些方法今天提供了观察迁移细胞、检查亚细胞结构分布、绘制基因表达图或形成根据样品分子结构编码的“化学图像”的能力。尽管光学显微镜取得了巨大的成功，但它在分辨小于几百纳米的特征方面的能力从根本上受到限制。具体地说，衍射极限使来自物体中的点的光在传播通过透镜时扩散开，从而在放大时使图像模糊。近场显微镜通过将光学探针放置在距离物体几十纳米的地方，并在其经历衍射之前对发射或散射的光进行采样，克服了这些限制。波士顿大学的研究人员正在建造一种多功能近场显微镜，为当地和区域用户提供10纳米量级的光学分辨率。该仪器正在实现一系列重要的研究目标，包括（i）研究蛋白质折叠行为，可以揭示阿尔茨海默氏症等疾病;（ii）开发用于激光源的新材料;（iii）工程方法单原子厚层的特性，如石墨烯用于下一代电子产品;（iv）在纳米尺度上控制光流动的方法，这对新的光学传感器和通信技术很重要。BU项目还让女性和代表性不足的少数民族本科生参与前沿研究。由于能够“看到”纳米级的物体对年轻人来说是一个强大的动力，该团队正在与BU的向上约束数学科学为城市高中生提供为期7周的住院大学预科课程。夏季的每个星期三，学生都会进行纳米技术动手实验，并使用新型显微镜观察纳米世界。光学显微镜可以说是有史以来最成功的非侵入性检查微观世界的技术之一，但从根本上限制了100 nm或更长的衍射极限的长度尺度。近场显微镜通过将源或探针放置到样品的近光场中以将非传播或倏逝模式耦合到远场传播模式中以用于收集来克服这一点。虽然有5到6家公司销售近场显微镜，但所有公司的能力都有限。波士顿大学的研究人员正在建立一个多功能的全息纳米级光学仪器集成到原子力显微镜，结合近场光谱的弹性散射，拉曼和荧光在很宽的波长范围。该仪器在传输和反向散射几何结构中运行，并包括用于相位分辨近场成像的干涉测量，以绘制3D场响应，提供了对推进复杂研究问题至关重要的灵活性和灵活性。该仪器使BU和区域大学的研究人员能够研究等离子体、生物物理学、石墨烯和其他二维（2D）晶体膜物理学中的纳米级光学现象。等离子体研究正在探索热点，局部态密度，特别是预测在金属和电介质组件之间的界面处发生的相位奇点。在石墨烯，MoS 2和hBN的应变工程2D晶体中，BU的研究人员正在探索原子级摩擦和映射应变诱导伪磁场的可能性。在锗半导体纳米膜的研究中，局域光学响应可以确认和帮助设计具有直接带隙的纳米器件。在生物物理学中，长波长尖端增强近场显微镜可以提供前所未有的固有振动模式图像，能够进行亚细胞分类和重要蛋白质的局部存在。