| 摘要 |
A method and apparatus for measuring ultrasonic properties within an object under evaluation, in particular, acoustic velocities and attenuation-frequency functions within the object. A transducer transmits a train of ultrasonic energy toward a reference object, and receives ultrasonic echoes reflected therefrom. The transducer transmits an identical train of ultrasound toward the object under evaluation, and receives ultrasonic echoes reflected from the latter object. A computer analyzes each of the received echoes using a Fast Fourier Transform algorithm, to produce for each an array of amplitudes per frequencies. The computer divides the array produced from the object echoes by the array of the reference echo to produce a third array of amplitudes per frequencies, which is partially characterized by a recurring periodical increase and decrease in amplitude. The computer finds the frequency of such recurrence, and calculates an acoustic velocity within the object, based on that frequency of recurrence and on the predetermined thickness of the object under evaluation. A display displays the calculated acoustic velocity. Based on the determined frequency of recurrence in the produced array of amplitudes per frequencies, the computer finds a subset of amplitudes per frequencies, which forms a function of attenuation per frequency in the object under evaluation. The display displays a graph of the determined attenuation-frequency function. In another embodiment, acoustic velocity is measured in several different locations on an object under evaluation. A location-monitoring device determines the location in which an acoustic velocity is measured. The determined location is stored in memory along with the acoustic velocity measured in that location. After obtaining a desired amount of acoustic velocities in different locations, the computer sends the accumulated measurements to a display, which displays an image of the object under evaluation, based on the acoustic velocities measured in different locations on the object.
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