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Lateral-looking Time-resolved Thermal Wave Microscopy
David H. Hurley,Subhash L. Shinde,Vitalyi E. Gusev 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.21
Time-resolved thermal wave microscopy was used to measure lateral thermal transport in a thin metallic film on an insulating substrate. The basis of this approach is to decompose the reflectivity signal into a component that varies with delay time and a steady state component that varies with pump modulation frequency. The transient component is a summation of thermal waves at integral multiples of the pulse repetition frequency (76 MHz). The steady state component depends only on thermal waves at the pump chopping frequency (10 - 100 kHz). For long delays, the steady-state component is dominant and can be used to measure the thermal diffusivity.
박승규,백성훈,차형기,Stephen J. Reese,David H. Hurley 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.21
Resonant ultrasound spectroscopy (RUS) is a useful technique for measuring the elastic properties of materials. In this study, two experimental approaches for performing RUS are experimentally analyzed and compared: 1) contact transduction using piezoelectric transducers (PZT) and 2) laser transduction using pulse laser excitation and laser interferometric detection. A single Zircaloy sample cut from a nuclear pressure tube was used for this study. By virtue of the non-contact nature, the quality factor, Q, for laser RUS is shown to be higher than the contact RUS. In addition, the probe beam for laser-RUS can be scanned to form a 2D image of each vibrational mode, which in turn enables unique mode identification. These defining characteristics of laser-RUS enable straightforward discrimination of closely spaced resonant modes and provide key advantages for improving the resolution of resonant ultrasound spectroscopy.