Magnetostrictive ultrasonic transducer

Claim 2

Apparatus for generating interrogating acoustic broadband pulses of predetermined duration for acoustically detecting variations in a given parameter by measuring the transmission of said pulses in a suitable sensor material in which the propagation of said pulses is variable as a function of the value of said parameter, said apparatus comprising: a transducer rod whose transverse dimensions are substantially smaller than the wavelength of pulses of said predetermined duration in said rod and whose length is substantially greater than that wavelength, at least one end of said rod being constructed of magnetostrictive material; means for providing a terminating impedance at said one end of said rod which is widely disparate from the characteristic acoustic impedance of said rod; a coil mounted coaxially with said rod at said one end thereof for generating interrogating acoustic pulses of said predetermined duration in said rod, said coil being configured to produce a magnetic field causing transduction in a portion of said rod which is substantially one-half wavelength; means for applying discrete electrical broadband pulses of said predetermined duration to said coil thereby to generate discrete acoustic wave pulses in said rod; and a lead-in assembly coupled to the other end of said rod for conveying said interrogating pulses to said sensor.

Claim 3

Apparatus as set forth in claim 1 wherein said coil is around said one end of said rod and wherein the effective length of said coil is substantially equal to half said wavelength.

Claim 4

Apparatus as set forth in claim 1 wherein said rod is tubular and said coil is within said tubular rod.

Claim 5

Apparatus as set forth in claim 3 wherein the interior of said tubular rod is threaded and the turns of said coil fit within those threads.

Claim 6

Apparatus as set forth in claim 1 wherein said one end of said rod is effectively supported in free space thereby to provide a reflection coefficient substantially equal to minus one.

Claim 7

Apparatus as set forth in claim 1 wherein said one end of said rod is in acoustic contact with a relatively massive terminating element thereby to provide a reflection coefficient substantially equal to plus one.

Claim 8

Apparatus as set forth in claim 1 wherein said coil is of a pancake configuration and is positioned adjacent said one end for generating radial shear waves in said rod.

Claim 9

Apparatus as set forth in claim 7 wherein said rod comprises a layer of magnetostrictive material at said one end of a rod the major portion of which is constructed of a nonmagnetostrictive material.

Claim 10

Apparatus for acoustically detecting variations in a given parameter by means of interrogating acoustic pulses of predetermined duration, the transmission of said pulses in a suitable sensor material being variable as a function of the value of said parameter, said apparatus comprising: a magnetostrictive transducer rod whose transverse dimensions are substantially smaller than the wavelength of pulses of said predetermined duration in said rod and whose length is substantially greater than that wavelength; means for supporting one end of said rod, said supporting means providing a terminating impedance at said one end which is widely disparate from the characteristic acoustic impedance of said rod; a coil mounted around said one end of said rod for generating interrogating acoustic pulses of said predetermined duration in saiD rod, the effective length of said coil encompassing said one end of the rod and being substantially equal to half the wavelength of said pulses in said rod; means for applying discrete broadband electrical pulses of said predetermined duration to said coil thereby to generate discrete interrogating acoustic wave pulses in said rod and for receiving reflections of said wave pulses; and a sensor assembly coupled to the other end of said rod for providing reflections of said interrogating pulses which vary as a function of the value of said parameter.

Claim 11

Apparatus for acoustically detecting variations in a given parameter by means of interrogating acoustic pulses of predetermined duration, the transmission of said pulses in a suitable sensor material being variable as a function of the value of said parameter, said apparatus comprising: a magnetostrictive transducer rod whose transverse dimensions are substantially smaller than the wavelength of pulses of said predetermined duration in said rod and whose length is substantially greater than that wavelength; means for supporting one end of said rod, said supporting means providing a terminating impedance at said one end which is widely disparate from the characteristic acoustic impedance of said rod; a coil mounted around said one end of said rod for generating interrogating acoustic pulses of said predetermined duration in saiD rod, the effective length of said coil encompassing said one end of the rod and being substantially equal to half the wavelength of said pulses in said rod; means for applying discrete broadband electrical pulses of said predetermined duration to said coil thereby to generate discrete interrogating acoustic wave pulses in said rod and for receiving reflections of said wave pulses; and a sensor assembly coupled to the other end of said rod for providing reflections of said interrogating pulses which vary as a function of the value of said parameter.

Claim 12

Apparatus as set forth in claim 9 wherein said one end of said rod is threaded and said supporting means lightly engages said threads on said rod.

Claim 13

Apparatus as set forth in claim 10 wherein said supporting means comprises a tube having a crimped portion engaging said rod.

Claim 14

Apparatus as set forth in claim 11 wherein said winding is wound on said tube.

Claim 15

Apparatus as set forth in claim 9 wherein said rod extends substantially beyond said winding and comprises an acoustic lead-in for coupling pulses to said sensor.

Claim 16

Apparatus as set forth in claim 9 wherein said rod terminates at said one end in a sharp, substantially right-angle bend and said supporting means engages the portion extending at right angles to the portion within said winding.

Claim 17

Apparatus for acoustically detecting variations in a given parameter by means of interrogating acoustic pulses of predetermined duration, the transmission of said pulses in a suitable sensor material being variable as a function of the value of said parameter, said apparatus comprising: a magnetostrictive transducer rod whose transverse dimensions are substantially smaller than the wavelength of pulses of said predetermined duration in said rod and whose length is substantially greater than that wavelength, one end of said rod being threaded; a tube having a portion of reduced diameter which is internally threaded for supporting said one end of said rod and providing a substantially short circuit acoustic terminating impedance at said one end; a coil mounted wound around said tube at said one end of said rod for generating interrogating acoustic pulses of said predetermined duration in said rod, the effective length of said coil encompassing said one end of the rod and being substantially equal to half the wavelength of said pulses in said rod; means for applying discrete broadband electrical pulses of said predetermined duration to said coil thereby to generate discrete interrogating acoustic wave pulses in said rod and for receiving reflections of said wave pulses; and a sensor assembly coupled to the other end of said rod for providing reflections of said interrogating pulses which vary as a function of the value of said parameter.

Claim 18

Apparatus for acoustically detecting variations in a given parameter by means of interrogating acoustic pulses of predetermined duration, the transmission of said pulses in a suitable sensor material being variable as a function of the value of said parameter, said apparatus comprising: a magnetostrictive transducer rod whose transverse dimensions are substantially smaller than the wavelength of pulses of said predetermined duration in said rod and whose length is substantially greater than that wavelength, one end of said rod being threaded; a tube having a portion of reduced diameter which is internally threaded for supporting said one end of said rod and providing a substantially short circuit acoustic terminating impedance at said one end; a coil mounted wound around said tube at said one end of said rod for generating interrogating acoustic pulses of said predetermined duration in said rod, the effective length of said coil encompassing said one end of the rod and being substantially equal to half the wavelength of said pulses in said rod; means for applying discrete broadband electrical pulses of said predetermined duration to said coil thereby to generate discrete interrogating acoustic wave pulses in said rod and for receiving reflections of said wave pulses; and a sensor assembly coupled to the other end of said rod for providing reflections of said interrogating pulses which vary as a function of the value of said parameter.

Claim 19

An acoustic transducer comprising: a pair of coaxial magnetostrictive elements; an acoustic lead-in member coaxial with said elements, one end of each element being acoustically coupled to said lead-in member; means for terminating the other end of one of said elements with a high acoustic impedance thereby to provide a reflection coefficient substantially equal to plus one, the other end of the other element being essentially free to provide a reflection coefficient substantially equal to minus one; and electromagnetic coil means adjacent the said other ends of said elements for generating acoustic pulses of substantially predetermined wavelength in said elements, the effective length of said coil means being substantially equal to half said wavelength, the acoustic pulses generated in the two elements combining at said lead-in member.

Claim 20

An acoustic transducer comprising: a pair of coaxial magnetostrictive elements; an acoustic lead-in member coaxial with said elements, one end of each element being acoustically coupled to said lead-in member; means for terminating the other end of one of said elements with a high acoustic impedance thereby to provide a reflection coefficient substantially equal to plus one, the other end of the other element being essentially free to provide a reflection coefficient substantially equal to minus one; and electromagnetic coil means adjacent the said other ends of said elements for generating acoustic pulses of substantially predetermined wavelength in said elements, the effective length of said coil means being substantially equal to half said wavelength, the acoustic pulses generated in the two elements combining at said lead-in member.

Claim 21

Apparatus for generating interrogating acoustic pulses of predetermined duration for acoustically detecting variations in a given parameter by measuring the transmission of said pulses in a suitable sensor material in which the propagation of said pulses is variable as a function of the value of said parameter, said appAratus comprising: a magnetostrictive transducer rod whose transverse dimensions are substantially smaller than the wavelength of pulses of said predetermined duration in said rod and whose length is substantially greater than that wavelength; means for supporting one end of said rod, said supporting means providing a terminating impedance at said one end which is widely disparate from the characteristic acoustic impedance of said rod; a coil for generating interrogating acoustic pulses of said predetermined duration in said rod, said one end of said rod extending part way into said coil with the effective length of said coil acting on said rod being preselected to be substantially equal to half the wavelength of said pulses in said rod; means for applying discrete electrical broadband pulses of said predetermined duration to said coil thereby to generate discrete acoustic wave pulses in said rod; and a lead-in assembly coupled to the other end of said rod for conveying said interrogating pulses to said sensor.

Claim 22

Apparatus for generating interrogating acoustic pulses of predetermined duration for acoustically detecting variations in a given parameter by measuring the transmission of said pulses in a suitable sensor material in which the propagation of said pulses is variable as a function of the value of said parameter, said appAratus comprising: a magnetostrictive transducer rod whose transverse dimensions are substantially smaller than the wavelength of pulses of said predetermined duration in said rod and whose length is substantially greater than that wavelength; means for supporting one end of said rod, said supporting means providing a terminating impedance at said one end which is widely disparate from the characteristic acoustic impedance of said rod; a coil for generating interrogating acoustic pulses of said predetermined duration in said rod, said one end of said rod extending part way into said coil with the effective length of said coil acting on said rod being preselected to be substantially equal to half the wavelength of said pulses in said rod; means for applying discrete electrical broadband pulses of said predetermined duration to said coil thereby to generate discrete acoustic wave pulses in said rod; and a lead-in assembly coupled to the other end of said rod for conveying said interrogating pulses to said sensor.