Surf Technology As

Other

Thor Andreas Tangen

Bjørn A J Angelsen

Rune Hansen

Tonni Franke Johansen

Svein-Erik Måsøy

Sven Peter Nasholm

Bjorn A J Angelsen

Sven Peter Näsholm

Sven Peter NÄSHOLM

Bjørn AJ Angelsen

Bjorn Angelsen

The invention presents methods and instrumentation for measurement or imaging of a region of an object with waves of a general nature, for example electromagnetic (EM) and elastic (EL) waves, where the material parameters for wave propagation and scattering in the object depend on the wave field strength. The invention specially addresses suppression of 3order multiple scattering noise, referred to as pulse reverberation noise, and also suppression of linear scattering components to enhanced signal components from nonlinear scattering. The pulse reverberation noise is divided into three classes where the invention specially addresses Class I and Class II 3order multiple scattering that are generated from the same three scatterers, but in opposite sequence.

Nonlinear imaging with dual band pulse complexes

Measurement or imaging of elastic wave nonlinear scatterers with a memory of scattering parameters comprises selecting LF pulses having characteristics to change the scattering parameters of nonlinear scatterers. A transmit time relation is selected so that the incident HF pulse propagates sufficiently close to the LF pulse that the effect of the incident LF pulse on its scatterer parameters is observed by the HF pulse. At least two elastic wave pulse complexes comprising a high frequency (HF) pulse and a selected low frequency (LF) pulse are transmitted towards the region. Received HF signals are combined to form nonlinear HF signals representing the scatterers with memory, with suppression of received HF signals from other scatterers. At least one of the received HF signals may be corrected by time delay correction and/or speckle correction with a speckle correction filter, determined by movement of the scattering object. Systems are also disclosed.

Measurement and imaging of scatterers with memory of scatterer parameters using at least two-frequency elastic wave pulse complexes

1and 2pulsed waves are transmitted along 1and 2transmit beams where at least one of the beams is broad in at least one direction, and the transmit timing between said 1and 2pulsed waves are selected so that the pulsed wave fronts overlap in an overlap region R(r,t) that propagates along at least one measurement or image curve &#x393;(r) in the material object. At least the scattered signal produced by nonlinear interaction between said 1and 2waves in the overlap region is received and processed to form a nonlinear interaction scattering image signal along &#x393;(r). The measurement or image curve &#x393;(r) can be scanned laterally by either changing of the relative transmit timing between the 1and 2pulsed waves or the direction of at least one of the 1and 2transmit beams, or both. The methods are applicable to image nonlinear scattering sources for both electromagnetic and elastic waves, and combinations of these.

Method for imaging of nonlinear interaction scattering

Elastic wave pulse complexes are transmitted towards said region where said pulse complexes are composed of a high frequency (HF) and a low frequency (LF) pulse with the same or overlapping beam directions and where the HF pulse is so close to the LF pulse that it observes the modification of the object by the LF pulse at least for a part of the image depth. Received HF signals are picked up by transducers from scattered and/or transmitted components of the transmitted HF pulses. The received HF signals are processed to form measurement or image signals for display, and combined in slow time to form noise suppressed HF signals or nonlinear scattering HF signals.

Nonlinear elastic wave measurement and imaging with two-frequency elastic wave pulse complexes

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Trondheim, Norway

Thor Andreas Tangen