title: Two-dimensional virtual array for ultrasonic nondestructive evaluation using a time-reversal chaotic cavity.
abstract: Despite its introduction more than a decade ago, a two-dimensional ultrasonic array remains a luxury in nondestructive evaluation because of the complexity and cost associated with its fabrication and operation. This paper describes the construction and performance of a two-dimensional virtual array that solves these problems. The virtual array consists of only two transducers (one each for transmit and receive) and an aluminum chaotic cavity, augmented by a 10  ×  10 matrix array of rectangular rods. Each rod, serving as an elastic waveguide, is calibrated to emit a collimated pulsed sound beam centered at 2.5 MHz using the reciprocal time reversal. The resulting virtual array is capable of pulse-echo interrogation of a solid sample in direct contact along 10  ×  10 scan lines. Three-dimensional imaging of an aluminum test piece, the nominal thickness of which is in the order of 1 cm, is successfully carried out using the virtual array.
authors.affiliation: School of Mechanical Engineering, Yonsei University, Seoul 120-749, Korea.
authors.forename: Youngsoo
authors.initials: Y
authors.lastname: Choi
authors.forename: Hunki
authors.initials: H
authors.lastname: Lee
authors.forename: Hyun
authors.initials: H
authors.lastname: Hong
authors.forename: Won-Suk
authors.initials: WS
authors.lastname: Ohm
mesh_terms: D000535:Aluminum; D004867:Equipment Design; D009038:Motion; D017711:Nonlinear Dynamics; D012815:Signal Processing, Computer-Assisted; D013016:Sound; D013997:Time Factors; D014159:Transducers; D014465:Ultrasonics / Q000295:instrumentation
chemical_list: D000535:Aluminum