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）显微镜可以说是对有史以来微观世界的非侵入性检查最成功的技术之一。罗伯特·胡克（Robert Hooke）创造了“细胞”一词，以描述他在17世纪首次通过显微镜观察到的软木塞的子结构。在过去的一个世纪中，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，检查亚细胞结构的分布，绘制基因表达或根据样品的分子结构编码的“化学图像”的能力。尽管取得了巨大的成功，但光学显微镜从根本上是限制了其解决少于几百纳米的功能的能力。具体而言，衍射极限会导致物体中的点的光在镜头传播时散布，从而在放大图像时模糊。近场显微镜通过将光学探针距离物体距离几十纳米，并在经历衍射之前对发射光进行采样或散射光，从而克服了这些局限性。波士顿大学的研究人员正在建造一种多功能的近场显微镜，可为本地和区域用户提供10纳米订单的光学分辨率。该仪器正在实现一系列重要的研究推力，包括（i）蛋白质折叠行为的研究，这些蛋白质折叠行为可以阐明诸如阿尔茨海默氏症之类的条件； （ii）开发激光来源的新材料； （iii）工程的方法，用于下一代电子的单个原子厚层（如石墨烯）和； （iv）控制纳米长度尺度上光流的方法，对于新的光学传感器和通信技术很重要。 BU项目还吸引了妇女和代表性不足的少数族裔本科生参与尖端研究。由于在纳米级“看到”对象的能力可以成为年轻思想的有力动力，因此该团队正在与BU的“向上绑定的数学科学”为7周的居住学院预科计划为城市高中生合作。夏季的每个星期三，学生都会进行纳米技术动手实验，并使用新的显微镜观察纳米世界。技术描述可以说是对有史以来微观世界的非侵入性检查的最成功的技术之一，但从根本上限于衍射极限的长度尺度为100 nm或更多。近场显微镜通过将源或探测器放入样品的近光场中克服了这一点，以将非寄生或逃生模式融入远场传播模式以进行收集。尽管有5或6家销售近场显微镜的公司，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种整合到原子力显微镜中的多功能全息纳米级光学仪器，将弹性散射，拉曼和荧光的近场光谱术结合在广泛的波长范围内。该仪器在变速箱和反向散射几何形状中都运行，并包括用于近距离近场成像的干涉测量法以映射3D场响应，从而提供了对加剧复杂研究问题至关重要的灵活性和敏捷性。该仪器使BU和区域大学的研究人员能够研究血浆，生物物理学和石墨烯以及其他二维（2D）晶体膜物理学中的纳米级光学现象。等离子研究正在探索热点，状态的局部密度，尤其是在金属和介电成分之间的界面上预测的相位奇异性。在石墨烯，MOS2和HBN的菌株工程2D晶体中，BU的研究人员正在探索原子尺度的摩擦，以及绘制应变诱导的伪磁场的令人兴奋的可能性。在对锗半导体纳米膜的研究中，局部光学响应可以用直接的带隙来确认并帮助工程纳米驱动器。在生物物理学中，长波长尖端增强的近场显微镜可以提供能够亚细胞分类和局部存在重要蛋白质的内在振动模式的前所未有的图像。