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.

快速、非接触式地表征表面水膜的特性，例如膜厚度、温度和溶解物质的浓度，在工程、生物学和医学的许多领域是一项具有挑战性的任务，因此，对于此类应用光学。作为 SCHU 1369/16-1 项目的延续，本项目以通过在 1.3 和 1.5 波长范围内应用基于二极管激光器的吸收传感器获得的结果为基础。 µm，可以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。迄今为止，该传感器仅在不太适合的传输模式下运行。对于实际应用，将升级为后向反射或后向散射几何形状的测量，并用于相应参数的动态测量，该测量基于测量选定二极管激光器的发射提供的多个波长的吸光度比。为了提高灵敏度，该传感器将配备 1.9 µm 的新型二极管激光器，其中水的吸光度明显更大。除了上面列出的参数外，还将以毫秒时间分辨率准同步确定水膜的特征量。传感器还将用于薄膜的 pH 测定测试，为了保持传感器的复杂性较低，将应用时分复用技术。此外，传感器在使用近红外时的适用性。 LED 作为二极管激光器的低成本替代品将被研究，第二个重要目标是将诊断方案从点测量扩展到二维成像，具有高重复率的 NIR 相机允许顺序测量相应的传输。波长，从而以二维方式确定薄膜特性。测量薄膜参数可达到的精度和准确度将使用贝叶斯推理方法进行量化。