Transducer Array Design Research Articles

The use of goal programming in the design of electroacoustic transducers and transducer arrays

The design of piezoelectric transducers or of acoustic transducer arrays often involves the satisfaction of multiple conflicting design specifications. To arrive at an optimal compromise solution to a specific design formulation, nonlinear goal programming techniques can be applied. In this paper, the section on transducer design contains a discussion of the mathematical model of a particular type of transducer and its associated housing. An example is given of a transducer constructed using the parameters indicated by the Goal Programming technique. In the section on array design, the compromise between beamwidth and side lobe level necessary in designing beam patterns is discussed and an example of the application of Goal Programming to the selection of array shading coefficients is given.

Design of ultrasound transducers using new piezoelectric ceramic materials

Three parameters α, DR and D n ( A), i.e. the efficiency, the dynamic range and the normalized axial resolution are used to evaluate the performance of ultrasound transducers for diagnostic imaging equipment. These parameters determine optimum conditions for use in the design of high frequency array transducers. A newly-developed piezoelectric ceramic material composed of (Pb,Sr)(Ti,Zr)O 3 or Pb[(Mg 1 3 , Nb 2 3 ), Ti,Zr]O 3 which satisfies the above-mentioned conditions was used to fabricate a co-phase array ultrasound transducer. The transducer showed good electrical and acoustic performance in accordance with theoretical considerations.

Electrical coupling effects in an ultrasonic transducer array

Ultrasonic imaging devices often use transducer arrays for sampling the incoming acoustic field and converting it into electrical signals. After some convenient processing (amplification, dephasing, summing, etc), the electrical signals are used to modulate the brightness of a cathode ray tube (crt) monitor on which the ultrasonic image becomes visible. The quality of the imaging apparatus depends critically on the transducer array design and implementation. Each individual transducer would, ideally, produce an electrical signal related exclusively to the ultrasonic field arriving at its surface; the reciprocal would also be true for transmission. In all practical cases, however, numerous effects lead to some coupling between nearby transducers, especially for very narrow transducers. The subsequent perturbations may be described as a narrowing of the radiation (or reception) pattern of the individual transducers, with respect to the theoretical predictions. To understand the mechanism for these couplings and to minimize them, their possible origins have been systematically studied. One of the most important sources of coupling is electrical leakage, which is reported here. Since no simple analytical calculation can be performed, diagrams have been established that enable evaluation of the electrical coupling against the dimensional characteristics of the array. Some means for reducing this coupling are suggested and comparative experimental results are given.

Design of slotted transducer arrays with matched backings.

A design procedure is described for acoustic transducer arrays suitable for focused acoustic imaging systems. The criteria governing the choice of the width of the individual elements of the array and for broadband matching are discussed. Experimental results on 2.5 MHz arrays are given and are in good agreement with theory.

Design of slotted transducer arrays with matched backings

A design procedure is described for acoustic transducer arrays suitable for focused acoustic imaging systems. The criteria governing the choice of the width of the individual elements of the array and for broadband matching are discussed. Experimental results on 2.5 MHz arrays are given and are in good agreement with theory.

Medical ultrasonic arrays

The subject of multielement ultrasonic transducers is presented, with emphasis on describing the ultrasonic transducer design techniques and time‐delay pulsing schedules used to achieve real‐time imaging, beam steering, and beam focusing. Transducer design techniques make use of a first‐order scattering theory in fluids, which model quite nicely many basic problems in diagnostic ultrasound. The various sidelobe energy and resolution problems are explored as a function of such transducer array design parameters as gapping effects, numbers of elements, ultrasonic excitation waveform shapes and frequencies, element size, and element electronic time‐delay pulsing schedules. The electronic time‐delay pulsing schedules are responsible for waveform constructive and destructive interference phenomena at points of interest in the ultrasonic field; the time‐delay schedules can, therefore, be used to achieve focusing and steering, in both linear array and rectangular array transducer systems. Time‐delay analysis and mechanical rotation concepts are used to achieve focusing and steering in annular array transducers. A comparison of the resolution characteristics of annular and linear array transducers is discussed. Axial and lateral resolution as a function of depth and various dynamic focusing concepts are also presented. An introduction to the problems and advantages of rectangular array transducer design is outlined. Sample theoretical and experimental results are presented to highlight the principle concepts associated with the design and utilization of ultrasonic transducer arrays in the medical field.

Design of optimum sonar transducer arrays using goal programming

The design of acoustic antenna arrays often involves the satisfication of multiple, conflicting design specifications. The use of conventional mathematical programming techniques in this endeavor have been inhibited by their inability to consider these multiple objectives within their design formulations. Most present techniques formulate the design problem in terms of a single objective subject to a set of design constraints which become difficult, if not impossible, to solve if these constraints are conflicting in nature. Goal Programming is an effective alternative methodology. Array pattern synthesis through Goal Programming provides the optimal solution to the multiple criteria design of various classes of acoustic antenna arrays. The design problems are formulated in terms of the multiple objectives expressed by the system response functions and the desired characteristics of the design parameters. The solution of two reasonably complex planar array designs is presented. The details of their formulation and solution provide an indication of the ability of this approach to resolve even more complex array design problems. [Work supported by Naval Sea Systems Command Code 0342.]

Design of transducer arrays with tapered side-lobe heights

Transducer arrays for many underwater sound applications have customarily been designed for equal sidelobe levels. This is, perhaps, as much due to the convenience of the analytical Dolph—Chebyshev technique as to any specific requirement. Using a simple adaptation of a previously reported numerical technique for symmetrical arrays [G. L. Wilson, J. Acoust. Soc. Am. 59, 195 (1976)], designs can be obtained whose directional response has a taper on the envelope enclosing the side lobes. The method is equally applicable to sum and to difference patterns. Examples are given. [This work was sponsored by the Naval Sea Systems Command, Code SEA-034.]

Design of Optimal Transducer Arrays

A generalized approach to the design of practical transducer arrays using recently developed mathematical optimization techniques is presented. The method generates the optimal array configuration and sets of element excitations to produce simultaneously a number of different three-dimensional patterns, which may be specified in any arbitrary planes. To ensure a practical design, the procedure is not limited to isotropic sources; it can also accommodate measured directivity characteristics of individual radiators. In addition, realistic bounds for all parameter values can be included. These variables are the location of the individual modules comprising the array and the excitation (amplitude and phase) of each module for each pattern. A computer program was written to implement this method, and two examples and of its use are presented: The first example treats the design of a linear array of eight isotropic radiators and shows that improvement over Dolph-Chebychev shading is possible; the second deals with a 12-element planar array required to produce, simultaneously, three patterns, each of which is specified in three planes.

Crystal Acoustic Arrays

A point source method for rapid design of a crystal transducer array using three crystal thicknesses in the ratio of 1:2:4 has been developed. Formulas are presented for main lobe width and ratio of secondary lobe amplitude to main lobe amplitude. For a 10×10 array (100 elements) this method of design leads to a relative side lobe level of 22 db as compared to a value for a uniform array of 13.4 db at the expense of having a beam width 1.25 times as wide as the uniform array.