CAREER: Spatially Resolved, Continuous Monitoring of Transient Processes Using Novel Optical Sensors

职业：使用新型光学传感器对瞬态过程进行空间分辨、连续监测

• 批准号: 0238633
• 负责人: Scott Sanders
• 金额: --
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-02-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0238633&HistoricalAwards=false
• 关键词: CAREER; Spatially; Resolved; Continuous; Monitoring

Intellectual meritThe research plan is centered around two techniques, both of which employ a Ti:sapphire laser and new wavelength-scanning techniques. A larger portion of the effort is devoted to two-photon direct absorption of xenon. In this technique, rapidly tunable ultraviolet light is used to monitor a xenon absorption feature in much the same way tunable diode lasers have been used to monitor water absorption in the near infrared. However, because the two-photon absorption in xenon is a nonlinear process, it occurs only where laser irradiance is high. Thus, in a focused laser beam, the process occurs only near the beam focus and not along the entire beam path. This property is exploited to extend standard direct-absorption techniques to enable spatial resolution. Spatial resolution in a line,plane, or volume are accomplished by rapidly scanning the laser focus through space using galvanometers. The technique monitors one property: xenon number density. However, because xenon is inert and easy to seed in a variety of environments, xenon number-density information is much more useful than it might seem on the surface. For instance, whenever pressure is known, gas temperature can be calculated from the xenon number density. In addition, by seeding xenon into one of multiple fluids in a mixing experiment, the xenon can be used to track that fluid even through chemical reactions that change its composition. The second technique uses new wavelength-scanning approaches to monitor Raman scattering spectra. This technique complements the xenon technique by offering more property information (e.g., simultaneous concentrations of multiple species) at the cost of lower signal levels. Applications in liquid and spray systems relevant to combustion are described. Although combustion sensing is of primary interest, both techniques are expected to be valuable for sensing in other environments as well.Broader impactA research and teaching plan for the next five years is laid out, designed to build a firm foundation future efforts. The research plan extends new laser wavelength-scanning concepts developed by the PI to provide continuous, spatially resolved gas and liquid property measurements of an unprecedented nature. Such data are obtained in fundamental and applied systems relevant to combustion, with the goal of dramatically improving the understanding of the governing processes. The research inspires the inclusion of active learning techniques into the undergraduate thermal-fluid science curriculum. Balanced by a traditional lecture-based format, these techniques are intended to foster creative thinking and physical familiarity with course material. Concept inventories are used to guide and assess the active learning exercises. In addition, undergraduate researchers (including students of under-represented groups), a graduate class in optical techniques, and outreach activities are integrated with the research program.

研究计划围绕两种技术，这两种技术都采用钛：蓝宝石激光器和新的波长扫描技术。 大部分的工作是致力于氙的双光子直接吸收。 在这种技术中，快速可调谐的紫外光用于监测氙的吸收特性，其方式与可调谐二极管激光器用于监测近红外线中的水吸收的方式大致相同。 然而，由于氙中的双光子吸收是一个非线性过程，它只发生在激光辐照度高的地方。 因此，在聚焦的激光束中，该过程仅发生在光束焦点附近，而不是沿着整个光束路径。 通过使用检流计在空间中快速扫描激光焦点来实现线、平面或体积中的空间分辨率。 该技术监测一个属性：氙数密度。 然而，由于氙是惰性的，并且容易在各种环境中播种，氙的数量密度信息比表面上看起来有用得多。 例如，只要压力已知，气体温度就可以从氙数密度计算出来。 此外，通过在混合实验中将氙气注入多种流体中的一种，氙气可以用来跟踪该流体，即使通过化学反应改变其成分。 第二种技术使用新的波长扫描方法来监测拉曼散射光谱。 该技术通过提供更多的属性信息（例如，多个种类的同时浓度），代价是较低的信号水平。 描述了在与燃烧有关的液体和喷雾系统中的应用。 虽然燃烧传感是主要的兴趣，这两种技术预计将是有价值的传感在其他环境以及。更广泛的影响未来五年的研究和教学计划，旨在建立一个坚实的基础，未来的努力。 该研究计划扩展了PI开发的新激光波长扫描概念，以提供前所未有的连续，空间分辨的气体和液体性质测量。 这些数据是在与燃烧相关的基础和应用系统中获得的，目的是大大提高对控制过程的理解。 这项研究启发了将主动学习技术纳入本科热流体科学课程。 通过传统的以讲座为基础的形式平衡，这些技术旨在培养创造性思维和对课程材料的物理熟悉。 概念清单用于指导和评估主动学习练习。 此外，本科生研究人员（包括代表性不足的群体的学生），光学技术研究生班和外展活动与研究计划相结合。