Elastic waveguide utilizing an enclosed core member

Claim 2

In combination, an elongated member comprising a flexible fiber core of a material in which elastic waves can be propagated, an enclosing member surrounding all surfaces except end surfaces of said elongated member and comprising a tube of the same material as said core, means for supporting said elongated member within said enclosing member, said supporting means including means for focusing elastic wave energy inward toward said elongated member so that the particle displacement profile of the combined elongated member, enclosing member, and supporting means in response to a propagating elastic wave has substantially zero amplitude at a radius, from the central longitudinal axis of said elongated member, which is no greater than the outer radius of said enclosing member, and said supporting means and included focusing means including at least one ribbon of said material exTending between an inside wall of said tube and said core to hold said core in spaced relation with respect to said tube, said ribbon extending along the length of said core and having a tapered cross section of decreasing thickness from said tube to said core.

Claim 3

In a waveguide for elastic waves, a core region of a material in which bulk elastic waves can be propagated, said core region having a diameter which is at least two wavelengths of elastic wave energy at the cutoff frequency fco of the lowest mode for said waveguide, a cladding region enclosing all surfaces except end surfaces of said core region, said cladding region also being of a material in which bulk elastic waves can be propagated, and at least one of said core region and said cladding region including means for focusing elastic wave energy toward said core region.

Claim 4

In a waveguide for elastic waves, a core region of a material in which bulk elastic waves can be propagated, said core region having a diameter which is at least two wavelengths of elastic wave energy at the cutoff frequency fco of the lowest mode for said waveguide, a cladding region enclosing all surfaces except end surfaces of said core region, said cladding region also being of a material in which bulk elastic waves can be propagated, and at least one of said core region and said cladding region including means for focusing elastic wave energy toward said core region.

Claim 5

The waveguide in accordance with claim 2 in which said lowest mode is the principal mode propagated in said waveguide, said core region diameter and said core region and cladding region materials being selected so that said cutoff frequency is of the form

Claim 6

In a waveguide for elastic waves, a core region of a material in which bulk elastic waves can be propagated, a cladding region including a tube enclosing all surfaces except end surfaces of said core region, said cladding region also being of a material in which bulk elastic waves can be propagated, and at least one of said core region and said cladding region including means for focusing elastic wave energy toward said core region, said focusing means comprising at least one ribbon supporting said core region within said cladding region and in spaced relation from an inner surface of said tube, said ribbon extending along said core and having a tapered cross section of decreasing thickness from said tube to said core.

Claim 7

In a waveguide for elastic waves, a core region of a material in which bulk elastic waves can be propagated, a cladding region including a tube enclosing all surfaces except end surfaces of said core region, said cladding region also being of a material in which bulk elastic waves can be propagated, and at least one of said core region and said cladding region including means for focusing elastic wave energy toward said core region, said focusing means comprising at least one ribbon supporting said core region within said cladding region and in spaced relation from an inner surface of said tube, said ribbon extending along said core and having a tapered cross section of decreasing thickness from said tube to said core.

Claim 8

In a waveguide for elastic waves, a core region of a liquid material in which bulk elastic waves can be propagated with a predetermined bulk longitudinal velocity, a cladding region enclosing all surfaces except end surfaces of said core region, said cladding region also being of a material in which bulk elastic waves can be propagated, and said cladding region material being a solid having a bulk shear velocity which is greater than said predetermined longitudinal velocity of said liquid material for focusing elastic wave energy toward said core region.

Claim 9

In a waveguide for elastic waves, a core region of a liquid material in which bulk elastic waves can be propagated with a predetermined bulk longitudinal velocity, a cladding region enclosing all surfaces except end surfaces of said core region, said cladding region also being of a material in which bulk elastic waves can be propagated, and said cladding region material being a solid having a bulk shear velocity which is greater than said predetermined longitudinal velocity of said liquid material for focusing elastic wave energy toward said core region.

Claim 10

In combination, an elongated member of a material in which elastic waves can be propagated, said member having an approximately circular cross section, a cladding on all surfaces except end surfaces of said member, said cladding also being of a material in which elastic waves can be propagated, the materials of said elongated member and said cladding being sufficiently different in character to have different shear wave velocities, with said elongated member having the lower such velocity so said member and cladding comprise a waveguide for elastic waves, and said cladding having a substantially uniform radial thickness which is a finite value dependent upon the particle displacement profile of the combined member and cladding materials, saId thickness being large enough so that said profile falls substantially to zero at a waveguide radius which is no greater than the outer radius of said cladding.

Claim 11

In combination, an elongated member of a material in which elastic waves can be propagated, said member having an approximately circular cross section, a cladding on all surfaces except end surfaces of said member, said cladding also being of a material in which elastic waves can be propagated, the materials of said elongated member and said cladding being sufficiently different in character to have different shear wave velocities, with said elongated member having the lower such velocity so said member and cladding comprise a waveguide for elastic waves, and said cladding having a substantially uniform radial thickness which is a finite value dependent upon the particle displacement profile of the combined member and cladding materials, saId thickness being large enough so that said profile falls substantially to zero at a waveguide radius which is no greater than the outer radius of said cladding.

Claim 12

The combination in accordance with claim 6 in which, said elongated member material is fused silica doped with titanium dioxide in sufficient percentage to provide said lower bulk shear wave velocity, and said cladding material is fused silica.

Claim 13

The combination in accordance with claim 6 in which, said elongated member material is fused silica, and said cladding material is fused silica doped with a sufficient percentage of alumina to provide said bulk shear wave velocity difference.

Claim 14

The combination in accordance with claim 6 in which said elongated member is a single crystal material.

Claim 15

The combination in accordance with claim 6 in which, said member material and said cladding material are the same except that at least one thereof is doped with a sufficient percentage of a different material to produce said bulk shear wave velocity difference.

Claim 16

The combination in accordance with claim 10 in which, said doping percentage concentration is graded with respect to waveguide radius over at least a portion of the radius of said waveguide to provide a relatively smooth transition between said different shear wave velocities.

Claim 17

The combination in accordance with claim 11 in which said doping percentage concentration is graded from a maximum concentration at the outer surface of said cladding to reduced concentrations with decreasing radii.

Claim 18

The combination in accordance with claim 6 in which, said waveguide is suspended in a motion absorbing material for cushioning said waveguide to protect it against external mechanical shock.

Claim 19

The combination in accordance with claim 6 in which said waveguide includes end portions of substantially enlarged cross sectional diameter as compared to an intermediate portion of said waveguide, and the cross sectional diameter of said waveguide is gradually tapered between each of said end portions and said intermediate portion.

Claim 20

The combination in accordance with claim 6 in which means are provided at at least one end of said waveguide for electromechanically transducing between electrical signals and elastic displacement signals, said transducing means comprising a member of piezoelectric material in contact with said one end, and electrode means secured to said piezoelectric member for bidirectionally coupling an electric field corresponding to either said electrical signals for one direction of tranducing or a predetermined mode of said elastic signals for the other direction of transducing.

Claim 21

The combination in accordance with claim 15 in which said piezolelectric member is a rectangular plate in intimate contact with said end of said waveguide, and said electrode means comprise a first pair of spaced electrodes on one face of said plate and in diametrically opposed quadrants of a projection on such face of the cross section of said elongated member, a second pair of spaced electrodes on the opposite face of said plate and in the corresponding quadrants of a projection on such face of the cross section of such elongated member, and electric circuit connections to said first and second pairs of electrodes for coupling electric signals of predetermined phases.

Claim 22

The combination in accordance with claim 16 in which said plate is oriented so that the particle displacement is in a direction parallel to the direction of diametric opposition of said first pair of electrodes, and said electric circuit connections include means for coupling said electric signals at said first and second pairs of electrodes in opposite phases for radial mode propagation in said waveguide.

Claim 23

The combination in accordance with claim 16 in which said plate is oriented so that the particle displacement is in a direction perpendicular to the direction of diametric opposition of said first pair of electrodes, and said electric circuit connections include means for coupling said electric signals at said first and second pairs of electrodes in opposite phases for torsional mode propagation in said waveguide.

Claim 24

The combination in accordance with claim 15 in which said piezolelectric member is a disk of ferroelectric ceramic material, said disk being electrically polarized in a circular direction in the plane of the disk, and said coupling means comprises electrodes arranged for coupling said electric field in a direction normal to the plane of the disk.

Claim 25

The combination in accordance with claim 15 in which, said piezoelectric member is a disk of ferroelectric material, said disk having a first direction which is radial with respect to the center thereof and a second direction which is orthogonal with respect to a face thereof, said disk being electrically polarized in one of said first and second directions, and said coupling means comprises electrodes arranged for applying said field to said disk in another of said first and second directions.

Claim 26

The combination in accordance with claim 20 in which said coupling means comprises, an annular electrode film on each face of said disk, and the outside diameter of said annular film being approximately the same as the outside diameter of said elongated member so that said film covers a region in said elongated member of maximum particle displacement during elastic wave propagation.

Claim 27

The combination in accordance with claim 6 in which the outside diameter of said cladding is at least twice the outside diameter of said elongated member.

Claim 28

The combination in accordance with claim 6 in which, said member and cladding materials also have predetermined respective bulk wave longitudinal velocities, and the longitudinal velocity of said member is less than the bulk shear wave velocity of said cladding.

Claim 29

The combination in accordance with claim 23 in which, said member material is chalcogenide glass, and said cladding material is fused silica.

Claim 30

The combination in accordance with claim 6 in which said elongated member and said cladding thereon have a particle displacement profile with respect to waveguide radius during propagation of an elastic wave, which profile is substantially symmetrical about a central longitudinal axis of said waveguide, and has a maximum displacement region within said elongated member.

Claim 31

An acousto-electric signal transducer for an elastic waveguide having a predetermined particle displacement profile characteristic for a transverse cross section thereof, said transducer comprising a plate of piezoelectric material, said plate being oriented for particle displacement in a predetermined direction in response to application of an electric field to said plate, means for coupling electric signals either to or from said plate at different surfaces of said plate such that an electric field extending between said surfaces and corresponding to said signals is normal to said particle displacement direction, said coupling means including electrodes placed so that when said plate is placed contiguous to an end cross section of said waveguide, said electric field covers maximum displacement portions of said profile, and said coupling means electrodes comprise a first pair of electrodes spaced from one another on a first one of said surfaces, a second pair of electrodes spaced from one another on a second one of said surfaces, said first and second surfaces being parallel to one another and the electrodes of said second pair being located in positions opposite to electrodes of said first pair, respectively, and electric circuit connections to said first and second pairs of electrodes for coupling electric signals of predetermined different phases.

Claim 32

An acousto-electric signal transducer for an elastic waveguide having a predetermined particle displacement profile characteristic for a transverse cross section thereof, said transducer comprising a plate of piezoelectric material, said plate being oriented for particle displacement in a predetermined direction in response to application of an electric field to said plate, means for coupling electric signals either to or from said plate at different surfaces of said plate such that an electric field extending between said surfaces and corresponding to said signals is normal to said particle displacement direction, said coupling means including electrodes placed so that when said plate is placed contiguous to an end cross section of said waveguide, said electric field covers maximum displacement portions of said profile, and said coupling means electrodes comprise a first pair of electrodes spaced from one another on a first one of said surfaces, a second pair of electrodes spaced from one another on a second one of said surfaces, said first and second surfaces being parallel to one another and the electrodes of said second pair being located in positions opposite to electrodes of said first pair, respectively, and electric circuit connections to said first and second pairs of electrodes for coupling electric signals of predetermined different phases.

Claim 33

The transducer in accordance with claim 26 in which said plate particle displacement is in a direction parallel to a line between centers of electrodes of said first pair, and said circuit connections include means for coupling said electric signals at said first and second pairs of electrodes in opposite phases for radial mode excitation in said plate.

Claim 34

The transducer in accordance with claim 26 in which said plate particle displacement is in a direction perpendicular to a line between centers of electrodes of said first pair, and said circuit connections include means for coupling said electric signals at said first and second pairs of electrodes in opposite phases for torsional mode excitation in said plate.

Claim 35

An acousto-electric signal transducer for an elastic waveguide having a predetermined particle displacement profile characteristic for a traverse cross section thereof, said transducer comprising a plate of piezoelectric, ferroelectric, ceramic material, said plate being poled in a circular direction in the plane of the plate and being oriented for particle displacement in a predetermined direction in response to application of an electric field to said plate, means for coupling electric signals either to or from said plate at different surfaces of said plate such that an electric field extending between said surfaces and corresponding to said signals is normal to said particle displacement direction, said coupling means including electrodes placed so that when said plate is placed contiguous to an end cross section of said waveguide said electric field covers maximum displacement portions of said profile, and said coupling means electrodes are in corresponding positions on opposite faces of said plate and centrally located over the region of circular poling in said plate.

Claim 36

An acousto-electric signal transducer for an elastic waveguide having a predetermined particle displacement profile characteristic for a traverse cross section thereof, said transducer comprising a plate of piezoelectric, ferroelectric, ceramic material, said plate being poled in a circular direction in the plane of the plate and being oriented for particle displacement in a predetermined direction in response to application of an electric field to said plate, means for coupling electric signals either to or from said plate at different surfaces of said plate such that an electric field extending between said surfaces and corresponding to said signals is normal to said particle displacement direction, said coupling means including electrodes placed so that when said plate is placed contiguous to an end cross section of said waveguide said electric field covers maximum displacement portions of said profile, and said coupling means electrodes are in corresponding positions on opposite faces of said plate and centrally located over the region of circular poling in said plate.

Claim 37

An acousto-electric signal transducer for an elastic waveguide having a predetermined particle displacement profile characteristic for a transverse cross section thereof, said transducer comprising a plate of piezoelectric, ferrroelectric, ceramic material, said plate having a first direction which is radial with respect to a predetermined center location therein and having a second direction which is normal to a major surface of said plate, said plate being poled in one of said first and second directions, and means for coupling electric signals either to or from said plate at different surfaces of said plate, and in another of said first and second directions, such that an electric field extending between said surfaces and corresponding to said signals is normal to said particle displacement direction, said coupling means including electrodes placed so that when said plate is placed contiguous to an end cross section of said waveguide said electric field covers maximum displacement portions of said profile.

Claim 38

An acousto-electric signal transducer for an elastic waveguide having a predetermined particle displacement profile characteristic for a transverse cross section thereof, said transducer comprising a plate of piezoelectric, ferrroelectric, ceramic material, said plate having a first direction which is radial with respect to a predetermined center location therein and having a second direction which is normal to a major surface of said plate, said plate being poled in one of said first and second directions, and means for coupling electric signals either to or from said plate at different surfaces of said plate, and in another of said first and second directions, such that an electric field extending between said surfaces and corresponding to said signals is normal to said particle displacement direction, said coupling means including electrodes placed so that when said plate is placed contiguous to an end cross section of said waveguide said electric field covers maximum displacement portions of said profile.