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Remote measurement of liquid water film thickness, temperature, and composition using near-infrared absorption

利用近红外吸收远程测量液态水膜厚度、温度和成分

基本信息

批准号：
229633504
负责人：
Professor Dr. Christof Schulz
金额：
--
依托单位：
Lehrstuhl für Reaktive Fluide
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/229633504?language=en
关键词：
Remote measurement liquid water film

项目摘要

The rapid, non-contact in situ characterization of properties of aqueous films on surfaces such as film thickness, temperature, and concentration of dissolved substances, is a challenging task in many areas of engineering, biology, and medicine. Therefore, for such applications optical diagnostics is the method of choice. As a continuation of the project SCHU 1369/16-1, the present project builds on results obtained through application of a diode laser-based absorption sensor in the wavelength range between 1.3 and 1.5 µm, which allows the detection of local properties of aqueous films, such as film thickness, temperature, and the concentration of dissolved substances (salts, urea). The sensor, which so far has been operated in a transmission mode only which is less suitable for practical applications, will be upgraded for measurements in retro-reflection or backscattering geometry and used for dynamic measurements of the respective parameters. The measurement is based on measuring absorbance ratios at several wavelengths provided by the emission of selected diode lasers. To achieve higher sensitivity, the sensor will be equipped with a new diode laser at 1.9 µm where the absorbance of water is significantly larger. The characteristic quantities of aqueous films will be determined quasi-simultaneously and at millisecond temporal resolution. In addition to the parameters listed above, the sensor will also be tested for pH determination of the film. In order to keep the complexity of the sensor low, a time-division multiplexing technique will be applied. Furthermore, the suitability of the sensor when using near-infrared LEDs as a low-cost alternative to diode lasers will be investigated. A second important goal is the expansion of the diagnostics scheme from point measurements towards two-dimensional imaging. An NIR camera with high repetition rate allows to sequentially measure the transmission on the respective wavelengths and thus determine the film properties in a two-dimensional manner. The achievable precision and accuracies of measured film parameters will be quantified using Bayesian inference methods.

在工程、生物学和医学的许多领域中，快速、非接触地原位表征表面上的水性膜的性质，例如膜厚度、温度和溶解物质的浓度，是一项具有挑战性的任务。因此，对于此类应用，光学诊断是首选方法。作为项目SCHU 1369/16-1的延续，本项目建立在通过应用波长范围在1.3和1.5 µm之间的二极管激光吸收传感器获得的结果的基础上，该传感器允许检测水膜的局部特性，例如膜厚度，温度和溶解物质（盐，尿素）的浓度。该传感器迄今为止仅以不太适合实际应用的透射模式工作，将进行升级，以进行逆向反射或反向散射几何测量，并用于动态测量相应参数。该测量基于测量由所选二极管激光器的发射提供的几个波长处的吸光度比。为了实现更高的灵敏度，传感器将配备一个新的1.9 µm二极管激光器，水的吸收率明显更大。水膜的特征量将被确定准同时和毫秒的时间分辨率。除上述参数外，还将对传感器进行薄膜pH值测定试验。为了保持传感器的复杂性低，时分复用技术将被应用。此外，当使用近红外LED作为二极管激光器的低成本替代品时，传感器的适用性将被研究。第二个重要的目标是扩展的诊断方案从点测量到二维成像。具有高重复率的NIR相机允许顺序地测量各个波长上的透射率，从而以二维方式确定膜的性质。将使用贝叶斯推断方法量化测量薄膜参数的可实现精密度和准确度。