This page has only limited features, please log in for full access.
We have newly developed coaxial and confocal optical-resolution photoacoustic microscopy based on sol-gel composite materials. This transducer contains a concave-shaped piezoelectric layer with a focus depth of 5 mm and a hole with a diameter of 3 mm at the center to pass a laser beam into a phantom. Therefore, this system can directly detect an excited photoacoustic signal without prisms or acoustic lenses. We demonstrate the capability of the system through pulse-echo and photoacoustic imaging experiments. The center frequency of the fabricated transducer is approximately 7 MHz, and its relative bandwidth is 86%. An ex-vivo experiment is conducted, and photoacoustic signals are clearly obtained. As a result, 2- and 3-dimensional maximum amplitude projection images are reconstructed.
Masayuki Tanabe; Tai Chieh Wu; Makiko Kobayashi; Che Hua Yang. Fabrication of Coaxial and Confocal Transducer Based on Sol-Gel Composite Material for Optical Resolution Photoacoustic Microscopy. Diagnostics 2019, 10, 6 .
AMA StyleMasayuki Tanabe, Tai Chieh Wu, Makiko Kobayashi, Che Hua Yang. Fabrication of Coaxial and Confocal Transducer Based on Sol-Gel Composite Material for Optical Resolution Photoacoustic Microscopy. Diagnostics. 2019; 10 (1):6.
Chicago/Turabian StyleMasayuki Tanabe; Tai Chieh Wu; Makiko Kobayashi; Che Hua Yang. 2019. "Fabrication of Coaxial and Confocal Transducer Based on Sol-Gel Composite Material for Optical Resolution Photoacoustic Microscopy." Diagnostics 10, no. 1: 6.
A position sensitive detector (PSD) is frequently used for the measurement of a one-dimensional position along a line or a two-dimensional position on a plane, but is more often used for measuring static or quasi-static positions. Along with its quick response when measuring short time-spans in the micro-second realm, a PSD is also capable of detecting the dynamic positions of moving objects. In this paper, theoretical modeling and experiments are conducted to explore the frequency characteristics of a vibrating string while moving transversely across a one-dimensional PSD. The theoretical predictions are supported by the experiments. When the string vibrates at its natural frequency while moving transversely, the PSD will detect two frequencies near this natural frequency; one frequency is higher than the natural frequency and the other is lower. Deviations in these two frequencies, which differ from the string’s natural frequency, increase while the speed of motion increases.
Che-Hua Yang; Tai-Chieh Wu. Vibration Measurement Method of a String in Transversal Motion by Using a PSD. Sensors 2017, 17, 1643 .
AMA StyleChe-Hua Yang, Tai-Chieh Wu. Vibration Measurement Method of a String in Transversal Motion by Using a PSD. Sensors. 2017; 17 (7):1643.
Chicago/Turabian StyleChe-Hua Yang; Tai-Chieh Wu. 2017. "Vibration Measurement Method of a String in Transversal Motion by Using a PSD." Sensors 17, no. 7: 1643.
In this study, a flexible ultrasonic transducer (FUT) was applied in a laser ultrasonic technique (LUT) for non-destructive characterization of metallic pipes at high temperatures of up to 176 °C. Compared with normal ultrasound transducers, a FUT is a piezoelectric film made of a PZT/PZT sol-gel composite which has advantages due to its high sensitivity, curved surface adaptability and high temperature durability. By operating a pulsed laser in B-scan mode along with the integration of FUT and LUT, a multi-mode dispersion spectrum of a stainless steel pipe at high temperature can be measured. In addition, dynamic wave propagation behaviors are experimentally visualized with two dimensional scanning. The images directly interpret the reflections from the interior defects and also can locate their positions. This hybrid technique shows great potential for non-destructive evaluation of structures with complex geometry, especially in high temperature environments.
Tai Chieh Wu; Makiko Kobayashi; Masayuki Tanabe; Che Hua Yang. The Use of Flexible Ultrasound Transducers for the Detection of Laser-Induced Guided Waves on Curved Surfaces at Elevated Temperatures. Sensors 2017, 17, 1285 .
AMA StyleTai Chieh Wu, Makiko Kobayashi, Masayuki Tanabe, Che Hua Yang. The Use of Flexible Ultrasound Transducers for the Detection of Laser-Induced Guided Waves on Curved Surfaces at Elevated Temperatures. Sensors. 2017; 17 (6):1285.
Chicago/Turabian StyleTai Chieh Wu; Makiko Kobayashi; Masayuki Tanabe; Che Hua Yang. 2017. "The Use of Flexible Ultrasound Transducers for the Detection of Laser-Induced Guided Waves on Curved Surfaces at Elevated Temperatures." Sensors 17, no. 6: 1285.
This research focused on characterization of mechanical properties in Nickel-Aluminum coating with different thermal technique and processing parameters at high temperature environment up to 295°C. With the laser ultrasound technique (LUT), guided acoustic waves are generated to propagate on the Ni-Al sprayed coatings. By measuring dispersive phase velocity followed by SCE-UA inversion algorithm. The Young's modulus of coatings which fabricated by HVOF technique is higher than APS technique. This technique is potentially useful to probe the material characterization at high temperature environment in a remote and non-destructive way.
Cheng Hung Yeh; Tai Chieh Wu; Che Hua Yang. Nondestructive Measurement Material Characterization of Thermal Sprayed Nickel Aluminum Coatings by using Laser Ultrasound Technique. Physics Procedia 2015, 70, 492 -495.
AMA StyleCheng Hung Yeh, Tai Chieh Wu, Che Hua Yang. Nondestructive Measurement Material Characterization of Thermal Sprayed Nickel Aluminum Coatings by using Laser Ultrasound Technique. Physics Procedia. 2015; 70 ():492-495.
Chicago/Turabian StyleCheng Hung Yeh; Tai Chieh Wu; Che Hua Yang. 2015. "Nondestructive Measurement Material Characterization of Thermal Sprayed Nickel Aluminum Coatings by using Laser Ultrasound Technique." Physics Procedia 70, no. : 492-495.