Sensors and methods for generating spatially encoded acoustic fields by sound-emitting apertures with spatially varying frequency and bandwidth

1 . An acoustic transducer for generating and/or receiving a spatially structured acoustic field, comprising:

a total aperture which generates and/or received said acoustic field,

wherein said total aperture comprises a plurality of sub-apertures,

wherein each of said sub-apertures is arranged to receive and/or generate ultrasound having a specific frequency spectrum,

wherein the specific frequency spectra of at least two of said sub-apertures differ from each other,

wherein all sub-apertures of said total aperture are connected to a same electronic drive channel, and

wherein said total aperture is formed by a piezoelectric element, and wherein the sub-apertures are formed by regions of the piezoelectric element having different thickness.

2 . The acoustic transducer of claim 1 , wherein said plurality of sub-apertures are distributed substantially in a plane perpendicular to a direction of propagation of the acoustic field.

3 . The acoustic transducer of claim 1 , wherein the plurality of sub-apertures have, at least in part, different diameters.

4 . The acoustic transducer according to claim 1 , wherein said electrical drive channel is arranged to output an alternating signal having a predetermined frequency spectrum to said sub-apertures, said alternating signal exciting at least one movable element of each sub-aperture to vibrate.

5 . A transducer device comprising a plurality of periodically arranged acoustic transducers according to claim 1 , each transducer having and being connected to a separate electronic drive channel.

6 . A method of manufacturing an acoustic transducer for generating and/or receiving a spatially structured acoustic field, wherein the acoustic transducer comprises:

a total aperture which generates and/or receives said acoustic field,

wherein said total aperture comprises a plurality of sub-apertures,

wherein each of said sub-apertures is arranged to receive and/or generate ultrasound having a specific frequency spectrum,

wherein the specific frequency spectra of at least two of said sub-apertures differ from each other, and

wherein all sub-apertures of said total aperture are connected to a same electronic drive channel, wherein said method comprises:

determining a desired spatial acoustic field distribution of a total aperture;

obtaining, from the desired acoustic field distribution, parameters of a plurality of sub-apertures that form the total aperture,

wherein obtaining said parameters comprises at least one of: an analytical calculation of the parameters, a numerical calculation of the parameters, and a simulation method for the parameters.

7 . The method of claim 6 , wherein obtaining the parameters of said sub-apertures comprises: calculating partial acoustic field distributions each having a specific frequency spectrum such that a superposition of all partial acoustic field distributions results in the desired spatial acoustic field distribution, and obtaining parameters of the sub-apertures such that each sub-aperture is designed to produce one of the partial acoustic field distributions.

8 . The method of claim 6 , wherein said parameters of a sub-aperture comprise at least one of the following:

dimensions of a sub-aperture,

a geometric shape of a sub-aperture,

a thickness of a movable element of a sub-aperture, and

a relative arrangement of a sub-aperture within the total aperture.

9 . A method of decoding a spatially structured acoustic field comprising:

detecting an ultrasonic signal comprising reflected signals of an irradiated acoustic field, the irradiated acoustic field having a predetermined spatial structure, and

calculating, on the basis of said detected signal and said predetermined spatial structure of the irradiated acoustic field, a spatial distribution of reflecting elements which generate the reflected signals,

wherein said ultrasonic signal is detected using a transducer comprising:

a total aperture which generates and/or received said acoustic field,

wherein said total aperture comprises a plurality of sub-apertures,

wherein each of said sub-apertures is arranged to receive and/or generate ultrasound having a specific frequency spectrum,

wherein the specific frequency spectra of at least two of said sub-apertures differ from each other,

wherein all sub-apertures of said total aperture are connected to a same electronic drive channel, and

wherein said ultrasonic signal is present as an output signal of the one electrical drive channel of the transducer.

10 . The method of claim 9 , further comprising:

displaying a two-dimensional or three-dimensional image from said calculated spatial distribution of reflecting elements.