| 摘要 |
A method for creating an acoustic observation of a target volume, the method comprising the steps of transmitting a group of at least two acoustic pulses towards the target volume, receiving at least one detector an echo of the group scattered from the target volume, the echo having linear and nonlinear components, processing the scattered signal in such a way as to enhance at least part of the nonlinear component (and suppress the linear component) of the scattered signal in a signal P+, processing the scattered signal in such a way as to suppress at least part of the nonlinear component (and enhance the linear component) of the scattered signal in a signal P−, and producing a detection signal from a mathematical combination of the signals P+ and P−. The method can be used to suppress at least part of the non-linear component, and to enhance the linear component in order to improve the contrast of an image of an object located in water and surrounded by an oceanic bubble cloud, by utilising a ratio of signals P+ and P−. In other situations where bubbles are required to be enhanced in the image, such as in biomedical ultrasonics, the nonlinear component can be arranged to be enhanced, and the linear component suppressed, by utilising the ratio P−/P+.
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