Mechanical wave generator and method thereof
A wave generator has a wave emitter including an elongated dispersive waveguide and a source operatively connected to a first end of the waveguide. The source covers at least partially a surface area thereof. A signal generator is in operative connection with the transducer to create electrical signals. A computer is in operative connection with the signal generator to cause it to generate the electrical signals. A mechanical input wave is created by the source at the first end of the waveguide. The mechanical input wave is constructed independently of data related to a mechanical wave received from a source in the medium and taking into account the different predetermined propagation velocities of at least two component waves of the mechanical input wave so that they combine with each other at a second end of the waveguide to form the desired mechanical output wave in the medium.
1. A wave generator for emitting a desired mechanical output wave into a medium, the wave generator comprising:
a wave emitter including:
an elongated dispersive waveguide having a first end and a second end, when in operation the second end being at least partially in contact with the medium; and
a source operatively connected to the first end of the dispersive waveguide covering at least partially a surface area of the first end, the source being operative to generate a mechanical input wave in the dispersive waveguide based on electrical signals input to the source;
a signal generator in operative connection with the source, the signal generator being operative to create the electrical signals convertible by the source into the mechanical input wave in the dispersive waveguide; and
a computer in operative connection with the signal generator, the computer having a processor and a machine-readable storage medium, the machine-readable storage medium containing instructions that when executed by the processor causes the signal generator to create electrical signals convertible by the source into the mechanical input wave,
the mechanical input wave having at least two component waves, each of the at least two component waves having a unique predetermined propagation velocity through the dispersive waveguide,
the at least two component waves having one of different predetermined propagation velocities through the dispersive waveguide and a first relative phase shift being determined so as to be become, at the second end of the dispersive waveguide, a second relative phase shift different from the first relative phase shift owing to the predetermined propagation velocities through the dispersive waveguide of the at least two component waves,
wherein, if the at least two component waves have the different predetermined propagation velocities through the dispersive waveguide, the mechanical input wave is constructed (i) independently of data related to a mechanical wave received from a source in the medium and (ii) taking into account the different predetermined propagation velocities of the at least two component waves so that the at least two component waves combine at least partially with each other at the second end of the dispersive waveguide to form the desired mechanical output wave emitted into the medium.
2. The wave generator of claim 1 , wherein the mechanical input wave has a first duration in time, the desired mechanical output wave has a second duration in time, and the first duration in time is longer than the second duration in time.
3. The wave generator of claim 1 , wherein the mechanical input wave has a first amplitude, the desired mechanical output wave has a second amplitude, and the second amplitude is greater than the first amplitude.
4. The wave generator of claim 1 , wherein the at least two component waves have different associated frequencies, and the at least two component waves have a same associated mode of the waveguide.
5. The wave generator of claim 4 , wherein the same associated mode is a single mode of the waveguide.
6. The wave generator of claim 5 , wherein the single mode is a fundamental longitudinal mode of the waveguide.
7. The wave generator of claim 1 , wherein the at least two component waves have each an associated frequency and an associated mode of the waveguide, the at least two component waves have different associated modes, and the at least two component waves have a same associated frequency.
8. The wave generator of claim 1 , wherein the source operatively connected to the first end of the dispersive waveguide is a transducer.
9. The wave generator of claim 1 , wherein the source covers at least an entirety of the surface area of the first end of the dispersive waveguide.
10. The wave generator of claim 1 , further comprising at least one of an acoustic impedance coupler and an acoustic lens operatively connected to the second end of the dispersive waveguide.
11. The wave generator of claim 1 , wherein the desired mechanical output wave is focused.
12. The wave generator of claim 1 ,
wherein the source is a bi-directional source, and is further operative to generate output electrical signals from a reverse direction mechanical wave, the reverse direction mechanical wave propagating through the dispersive waveguide from the second end to the first end of the dispersive waveguide; and
the wave generator further comprising:
a switch in operative connection with the bi-directional source, the switch being operative to separate input electric signals to be input to the bidirectional source from output electric signals out from the bi-directional source; and
a digitizer in operative connection with the switch and with the computer, the digitizer being operative to digitize the output electrical signals for use by the computer.