Abstract: An ultrasound transducer employs a silicon acoustic matching layer closest to the piezoelectric layer in order to achieve improved resolution. A silicon wafer, ground to an appropriate thickness, is included in the acoustic stack with other matching layer materials during transducer construction. The exact thickness is determined by the details of the design, but is nominally a quarter wavelength in the silicon.

Abstract: An ultrasound transducer employs a silicon acoustic matching layer closest to the piezoelectric layer in order to achieve improved resolution. A silicon wafer, ground to an appropriate thickness, is included in the acoustic stack with other matching layer materials during transducer construction. The exact thickness is determined by the details of the design, but is nominally a quarter wavelength in the silicon.

Abstract: Harmonic imaging using harmonic Golay-coded excitation that encodes the fundamental and second harmonic signals utilizes the transmit sequences encoded using QPSK implemented as quarter-cycle circular rotations or shifts of the base pulse. This is implemented by time shifting the chips of the transmit sequence encoded with a “j” or “−j” code symbol by ¼ fractional cycle at center frequency relative to the chips encoded with a “1” or “−1” code symbol. A different QPSK transmit code is used for each of four transmits A, B, C and D. The transmit codes are selected such that (A-B) and (C-D) are encoded by Y and −X, respectively, while (A2-B2) and (C2-D2) are encoded by X and Y, respectively, where X and Y form a Golay code pair. The coding and decoding technique achieves fundamental suppression and second harmonic compression for a given Golay code pair X and Y.

Abstract: Harmonic imaging using harmonic Golay-coded excitation that encodes the fundamental and second harmonic signals utilizes the transmit sequences encoded using QPSK implemented as quarter-cycle circular rotations or shifts of the base pulse. This is implemented by time shifting the chips of the transmit sequence encoded with a “j” or “−j” code symbol by ¼ fractional cycle at center frequency relative to the chips encoded with a “1” or “−1” code symbol. A different QPSK transmit code is used for each of four transmits A, B, C and D. The transmit codes are selected such that (A−B) and (C−D) are encoded by Y and −X, respectively, while (A2−B2) and (C2−D2) are encoded by X and Y, respectively, where X and Y form a Golay code pair. The coding and decoding technique achieves fundamental suppression and second harmonic compression for a given Golay code pair X and Y.

Abstract: An ultrasound survey frame (SF) is processed in order to determine the portions representing fluid flow. An assembly (20) again rescans only the portions of a subject represented by the portions of the survey frame in which fluid flow was found. Target frames (TF) then are created from the rescanning and are processed in order to provide a color flow image restricted to the portions of the survey frame in which fluid flow is indicated.

Abstract: A method using a progressive sampling rate technique to maintain the sampling rate at the Nyquist frequency of the I/Q data through a tunable equalization bandpass filter in the front end of the imager and then increasing the sampling rate via axial interpolation to prevent aliasing during the nonlinear detection process. If an envelope detector is used, the bandwidth of the detector output should be approximately double that of the I/Q data. In this case, the sampling rate is doubled (or more) by axial interpolation before envelope detection. A 2-point linear interpolator can be used. Depending on the application, this axial interpolator can be turned on or off automatically by the system. After detection, the signal can be low-pass filtered to restrict the speckle bandwidth prior to log compression.

Abstract: A method for designing ultrasonic transducers used in diagnostic ultrasonic imagers, in particular, transducers made up of at least one piezoelectric layer and at least one acoustic matching layer, plus various bonding and backing layers. The method of transducer design uses a particular family of spectra as the basis of the bandpass characteristic. The approach is to specify a transfer function from the Transitional Butterworth Thompson family of spectra. The specification is influenced by trade-offs in bandwidth, transient response and design feasibility. This family is indexed by a design parameter called M. Using the M factor, a designer can more readily make the engineering trade-offs needed. By adjusting this parameter, any dynamic response from maximally flat to Gaussian can be obtained.