2.?Piezoelectric LSAW Detection EPZ-5676 molecular weight Technique and Differential Confocal LSAW Detection Technique2.1. Piezoelectric LSAW Detection Technique Based on A PVDF Foil TransducerThe piezoelectric LSAW detection technique is Inhibitors,Modulators,Libraries a classic method in laser ultrasonic detection Inhibitors,Modulators,Libraries technology. PVDF foils have a good acoustic impedance matching, wide measurement bandwidth, and high sensitivity for force-electric charge Inhibitors,Modulators,Libraries conversion, which makes this technique an excellent measurement method [17]. Moreover, piezoelectric foil transducers can be homemade easily [18]. For our experimental setup, a number of simple foil piezoelectric transducers were homemade, as well as innovative foil piezoelectric Inhibitors,Modulators,Libraries transducer structures [19].The schematic diagram of the piezoelectric SAW detection system is relatively simple.
In the system, a pulse laser is used to generate wideband surface acoustic waves. And then the surface acoustic waves are detected by a wideband piezoelectric transducer at different distances between the laser focus line focused by a cylindrical lens Drug_discovery and the transducer.2.2. Differential Confocal LSAW Detection Technique Based on the Principle of Light ReflectionThe differential confocal LSAW detection technique uses laser beam reflection for measuring Young’s modulus of thin films. The intensity of the reflected beam light ensures the system high sensitivity and rapid response characteristics, meanwhile, the differential signal sampling eliminates common disturbances, such as optical power fluctuations of the detector, ambient air convection, and electric noise, which in turn improves system’s signal-to-noise ratio and the ability to distinguish high-frequency SAW signals [11,12].
The schematic diagram of the integrated LSAW detection Tubacin microtubule system described in detail later in Section 3 includes a differential confocal LSAW detection system (Channel 2) previously developed by the research team [20]. In the system, the LSAW excitation part of the differential confocal system is the same with the piezoelectric system. However, the optical detection part uses a light probe emitted by a He-Ne laser to detect surface acoustic waves. The difference between the differential confocal LSAW detection method with the classic piezoelectric blade method is that the former relies on the focus change after the movement of the light and the latter is based on the principle of the exposed light energy change from the receiving surface.2.3. Comparison Test of the Piezoelectric LSAW Detection Technique and the Differential Confocal LSAW Detection TechniqueIn order to compare the performance of both techniques for Young’s modulus measurement, a comparative experiment was conducted. A thermal oxide SiO2 thin film on a Si (100) substrate was chosen as experimental sample.