Simultaneous determination of layer thickness and sound velocity for multifocal ultrasound microscopy

该项目的目的是提供一种多焦点超声显微镜系统，用于在不同深度同时进行调查，分析频率从100到大约100。250 MHz适用于广泛的研究学科。除了在电子检测中的应用，例如多层电子元件的检测，显微镜还为微流体和生物技术提供了许多创新动力。例如，由于测量时间大大缩短，生物过程的现场观察就变得触手可及。多焦点显微镜的优点在于可以改变焦点，从而聚焦到不同的深度，同时保持与研究对象的恒定距离，以及与单通道显微镜相比，在显著减少时间消耗的情况下提高精度。如果分层测试对象的材料组成和结构未知，则需要进一步开发和应用同时测定声速和距离的方法。该方法能够优化聚焦的延迟时间，从而实现最大可能的分辨率。由于高分析频率与多通道技术相结合，在以下方面出现了相当大的挑战：（i）由环形阵列和非球面透镜组成的系统的基于声场的设计，（ii）必要的高精度聚焦电子设备，（iii）提供用于处理高频信号的算法，以及（iv）确保高信号能量。要开发的预聚焦环形阵列的要求在于非常少量的元件与优异的聚焦特性以及阵列曲率和非球面透镜的精确匹配相结合，使得可以在测试对象的任何深度处实现波长范围内的聚焦区域的扩展。阵列的制造需要在透镜生产、振荡器元件的薄膜应用和电极结构化中使用最新的技术和制造技术。电子设备必须允许准同时控制各个阵列元件，以便将焦点放置在期望的平面中并极大地减少其延伸，以及记录、再现和任意处理高频信号。分析软件可提供高分辨率的准3D图像。这些任务的解决方案需要与一个实际的合作伙伴密切合作，该合作伙伴已经开发了单通道显微镜系统的电子和评估软件，并掌握了高频传感器的制造技术。

The aim of this project is to provide a multifocal ultrasound microscopy system for simultaneous investigation at different depths for analysis frequencies from 100 to approx. 250 MHz for a broad spectrum of research disciplines. Besides the application in the inspection of electronics, e.g. the inspection of multilayer electronic components, the microscope provides numerous innovation impulses for microfluidics and biotechnology. Due to the greatly reduced measuring time, for example, in-situ observation of biological processes is within reach.The advantages of a multifocal microscope consist in the possibility of varying the focal point and thus focusing to different depths while maintaining a constant distance to the studied object, as well as in an increased accuracy with considerably less expenditure of time compared to a single-channel microscope. If the material composition and structure of the layered test object is unknown, further development and application of the method for simultaneous determination of sound velocity and distance is necessary. The method enables the optimization of the delay times for focusing and thus the achievement of the maximum possible resolution. Because of the high analysis frequencies in combination with a multi-channel technique, considerable challenges arise with regard to: (i) the sound field-based design of the system consisting of annular array and aspherical lens, (ii) the necessary high-precision focusing electronics, (iii) the provision of algorithms for processing the high-frequency signals and (iv) ensuring high signal energy. The requirements for the pre-focused annular array to be developed consist in a very small number of elements combined with excellent focusing properties and an exact matching of array curvature and aspherical lens, so that the extension of focus area in the wavelength range can be achieved at any depth of the test object. The fabrication of the arrays requires the use of latest technology and manufacturing technologies in lens production, the thin-film application of the oscillator elements and electrode structuring. The electronics must allow quasi-simultaneous control of the individual array elements in order to place the focus in the desired plane and to reduce its extension extremely, as well as to record, digitize and arbitrarily process high-frequency signals. The analysis software delivers high-resolution quasi-3D images.The solution of these tasks requires close cooperation with a practical partner who has already developed electronics and evaluation software for single-channel microscopy systems and has mastered the manufacturing technology for high-frequency transducers.