Optical Fabric and Fiber Logging of Glacial Ice

该奖项支持一个项目，该项目结合冰川学家和光学工程师的专业知识，开发用于钻孔工具的保偏振光学散射技术，以识别冰川冰的高分辨率晶体结构（织物）和粉尘含量的变化。这项工作的智力价值在于，冰的结构和杂质含量包含了气候、火山活动和冰流历史的细节。目前的测量方法是在冰芯开始减压后，将其切成几段，这是一个非常耗时的过程，会损坏冰芯，而且并不总是能保持冰在原位状态下的特性。此外，为了测量粉尘的成分，通常必须消耗冰芯。本研究的织物测量利用了这样一个概念，即冰中的单散射光在从气泡或尘埃中反向散射一次时保留了大部分偏振；因此，单背散射光的偏振变化一定是由双折射引起的。基于这一概念的测量将使该程序能够获得织物的连续记录，并将其与年代和粉尘含量相关联。该项目还将开发先进的井眼仪器，以取代目前的测井工具，这些测井工具需要将光源、探测器和电源线浸入井眼流体中，并在零下50摄氏度的温度下下放到冰盖中。通信光纤的使用将允许所有源和探测器保持在地面，并实现低噪声信号处理技术，如锁相放大，从而提高信号完整性并降低所需功率。此外，光纤测井系统将比现有的工具更小、更灵活，无需重型绞车即可导航大多数井眼。为了在现场评估织物和测试光纤钻孔工具，将在南极洲西部的WAIS Divide进行现场测量，并在simple Dome进行深层测井。如果成功，拟议的研究将产生更广泛的影响，包括开发新的分析方法和用于冰钻研究的轻型测井工具，这些工具可以在冰钻的井眼中操作。最终，这项工作可能会导致更好的史前冰川流动、大气微粒、降水和气候强迫记录的发展。该项目包括理论、实验和设计工作的广泛基础，使其成为培养研究生和高级本科生的理想选择。与学校和课堂教师的合作将有助于将光学、气候和极地科学的各个方面引入现有的中学课程。

1142010/TalghaderThis award supports a project to combine the expertise of both glaciologists and optical engineers to develop polarization- preserving optical scattering techniques for borehole tools to identify changes in high-resolution crystal structure (fabric) and dust content of glacial ice. The intellectual merit of this work is that the fabric and impurity content of the ice contain details on climate, volcanic activity and ice flow history. Such fabric measurements are currently taken by slicing an ice core into sections after it has started to depressurize which is an extremely time-intensive process that damages the core and does not always preserve the properties of ice in its in-situ state. In addition the ice core usually must be consumed in order to measure the components of the dust. The fabric measurements of this study utilize the concept that singly-scattered light in ice preserves most of its polarization when it is backscattered once from bubbles or dust; therefore, changes to the polarization of singly-backscattered light must originate with the birefringence. Measurements based on this concept will enable this program to obtain continuous records of fabric and correlate them to chronology and dust content. The project will also develop advanced borehole instruments to replace current logging tools, which require optical sources, detectors and power cables to be submerged in borehole fluid and lowered into the ice sheet at temperatures of -50oC. The use of telecommunications fiber will allow all sources and detectors to remain at the surface and enable low-noise signal processing techniques such as lock-in amplification that increase signal integrity and reduce needed power. Further, fiber logging systems would be much smaller and more flexible than current tools and capable of navigating most boreholes without a heavy winch. In order to assess fabric in situ and test fiber-optic borehole tools, field measurements will be made at WAIS Divide and a deep log will also be made at Siple Dome, both in West Antarctica. If successful, the broader impacts of the proposed research would include the development of new analytical methods and lightweight logging tools for ice drilling research that can operate in boreholes drilled in ice. Eventually the work could result in the development of better prehistoric records of glacier flow, atmospheric particulates, precipitation, and climate forcing. The project encompasses a broad base of theoretical, experimental, and design work, which makes it ideal for training graduate students and advanced undergraduates. Collaboration with schools and classroom teachers will help bring aspects of optics, climate, and polar science to an existing Middle School curriculum.