Schlieren Observation of Focused-Ultrasound Wave Propagation Interfered by Rib-Type Obstacles

• Main Authors: Tsung Ying Chen, 陳聰瑛
• Other Authors: H. L. Liu
• Format: Others
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/31686164638547855554

碩士 === 長庚大學 === 電機工程學研究所 === 97 === Research in recent years, the Schlieren method in the field of application of ultrasound is well-known methods. In the past, ultrasound measurement equipment, usually in the hands of three-dimensional mechanical pressure distribution of water as a standard; schlieren imaging to determine the pressure distribution is another way. This method is based on visual imaging technology rather than the traditional mechanical handset water[1]. The purpose of this study is the use of schlieren method observed by focused ultrasound rodded heterogeneous material after the impact of interference. In this study, the use of laser as a light source, a CCD Camera to capture images, before returning to deal with client computer. In the video capture, respectively, there is a check and an ultrasound signal is no ultrasound images, two images do subtraction, and then by the image processing, will be generated by the interference of ultrasound schlieren, in order to observe the ultrasonic sound pressure distribution[1, 2]. Experiments were 1.64 MHz and 400 kHz for the focused ultrasound testing, and different materials for gate-like heterojunction acoustic interference. Experimental results show that heterogeneity of grid-like on the 1.64 MHz and 400 kHz ultrasonic ultrasound will produce the interference. Grid-like material heterogeneity on the quantity or location of the sound field are in varying degrees of interference and attenuation of sound pressure.