Multilayer backing absorber for ultrasonic transducer

1. A backing absorber for use with an ultrasonic transducer, comprising:

a first absorber element having at least one homogeneous metal layer and at least one adhesive layer; and

a second absorber element having at least one homogeneous metal layer and at least one adhesive layer,

wherein said backing absorber is adapted to be coupled to a vibrating layer of said ultrasonic transducer,

wherein said first and second absorber elements are effective to dampen ultrasonic signals emitted by said vibrating layer when said backing absorber is coupled to said vibrating layer, and

wherein each absorber element further includes a polymer layer.

2. The backing absorber of claim 1 , wherein each of said at least one metal layers is deposited on a corresponding one of said polymer layers to form a periodic grating of metal strips wherein the direction and period of the grating is the same for each absorber element.

3. The backing absorber of claim 2 , wherein the vibrating layer comprises a 2-2 PZT composite having a plurality of elongated bars of PZT material and wherein the direction of the elongated metal area of the grating is perpendicular to said PZT bars.

4. The backing absorber of claim 1 , wherein each of said at least one metal layers is deposited on a corresponding one of said polymer layers to form a periodic grating of metal strips wherein the direction or period of the grating is different for each absorber element.

5. The backing absorber of claim 4 , wherein said direction of said grating is positioned at a 90 degree angle relative to the direction of the grating of each adjacent absorber element.

6. The backing absorber of claim 1 , wherein each of said at least one metal layers is partially deposited on a selected area of a corresponding one of said polymer layers to form a boundary grading for reflecting backwards waves in such a way as to increase effective attenuation.

7. The backing absorber of claim 1 , wherein the vibrating layer comprises one of a monolithic PZT plate, a 1-3 PZT composite, and a 2-2 PZT composite.

8. A method of making a backing absorber for an ultrasonic transducer, comprising:

forming a first absorber element by coupling a first homogeneous metal layer to a first adhesive layer and coupling a first polymer layer to said first homogeneous metal layer; and

forming a second absorber element by coupling a second homogeneous metal layer to a second adhesive layer and coupling a second polymer layer to said second homogeneous metal layer,

wherein a surface of said first absorber element is configured to be coupled to a corresponding surface of a vibrating layer of said ultrasonic transducer for absorbing ultrasonic waves.

9. The method of claim 8 further comprising:

forming an additional absorber element by coupling a third metal layer to a second adhesive layer; and

bonding said additional absorber element to said second absorber element.

10. The method of claim 9 further comprising:

repeating said forming of said additional absorber elements and said bonding of said additional absorber elements until a predetermined acoustic absorption value has been reached.

11. The method of claim 8 , wherein said forming each absorber element further comprises depositing said metal layer on said polymer layer to form a periodic grating of metal strips wherein the direction and period of the grating is the same for each absorber element.

12. The method of claim 8 , wherein said forming each absorber element further comprises depositing said metal layer on said polymer layer to form a periodic grating of metal strips wherein the direction or period of the grating is different for each absorber element.

13. The method of claim 12 , wherein said direction of said grating is positioned at a 90 degree angle relative to the direction of the grating of each adjacent absorber element.

14. The method of claim 8 , wherein said forming further comprises partially depositing said metal layers on a selected area of said polymer layers to form a boundary grading for reflecting waves in such a way as to increase effective attenuation.

15. An ultrasonic transducer assembly, comprising:

a vibrating layer for generating ultrasonic waves; and

a backing absorber coupled to said vibrating layer for absorbing said ultrasonic waves, said backing absorber having a plurality of absorber elements, each absorber element including a metal layer, a polymer layer, and an adhesive layer.

16. The ultrasonic transducer assembly of claim 15 , wherein the vibrating layer comprises one of a monolithic PZT plate, a 1-3 PZT composite, and a 2-2 PZT composite.

17. A backing absorber for use with an ultrasonic transducer, comprising:

a first absorber element having at least one homogeneous metal layer and at least one adhesive layer; and

a second absorber element having at least one homogeneous metal layer and at least one adhesive layer,

wherein said backing absorber is adapted to be coupled to a vibrating layer of said ultrasonic transducer,

wherein said first and second absorber elements are effective to dampen ultrasonic signals emitted by said vibrating layer when said backing absorber is coupled to said vibrating layer, and

wherein each of said at least one metal layers forms a periodic grating of metal strips, wherein the direction or period of the grating is different for each absorber element.

18. The backing absorber of claim 17 , wherein said direction of said grating is positioned at a 90 degree angle relative to the direction of the grating of each adjacent absorber element.