Transparent ultrasound transducer with light beam shaping and the method for assembling the same

1. A transducer unit for optical-acoustic imaging, comprising:

a transparent piezoelectric transducer configured to receive acoustic waves from a target, wherein the transparent piezoelectric transducer comprises:

a first transducer electrode comprising a flat surface; and

a second transducer electrode comprising a concave surface; and

a backing layer directly contacted with and optically coupled to the first transducer electrode along a vertical axis,

wherein:

an illumination to the target is provided through the backing layer and the transparent piezoelectric transducer along the vertical axis; and

the concave surface is smooth and continuous with a radius of curvature determined based on a focal length for focusing the acoustic waves reflected from the target.

2. The transducer unit of claim 1 , wherein the second transducer electrode further comprises peripheries of the concave surface, wherein the peripheries are smooth and flat.

3. The transducer unit of claim 2 , wherein the flat surface, the concave surface, and the peripheries of the concave surface are coated with transparent electrically conductive coatings.

4. The transducer unit of claim 3 , wherein the transparent electrically conductive coatings are made of indium tin oxide (ITO), tin oxide, indium oxide, zinc oxide, or any combination thereof.

5. The transducer unit of claim 1 , wherein the first and second transducer electrodes are physically and electrically separated for enabling measurement of the acoustic waves, and wherein the first and second transducer electrodes are separately connected to external connectors at a distal end via one or more wires for analyzing the acoustic waves.

6. The transducer unit of claim 5 , wherein a shield wire is provided between the first and second transducer electrodes to prevent forming a short-circuit path.

7. The transducer unit of claim 1 , wherein the backing layer is an optical lens for improving a signal-to-noise ratio of the transparent piezoelectric transducer and configured to transmit and shape the illumination to the target.

8. The transducer unit of claim 7 , wherein the optical lens is a gradient-index (GRIN) lens designed for shaping the illumination in the form of a focusing beam, a collimating beam, or a diverging beam by varying an index of refraction.

9. The transducer unit of claim 7 , wherein the optical lens comprise one or more optical elements arranged to form a focusing lens, a collimating lens, or a diverging lens, wherein the one or more optical elements are selected from the group consisting of one or more mirrors, lens, collimators, prisms, diverging elements, and diffractive elements.

10. The transducer unit of claim 1 , wherein the transparent piezoelectric transducer and the backing layer have substantially similar acoustic impedances to minimize an acoustic impedance mismatch such that sensitivity of the transducer unit is improved.

11. The transducer unit of claim 1 , wherein the backing layer is adhesively attached to the first transducer electrode of the transparent piezoelectric transducer.

12. The transducer unit of claim 1 , wherein the transparent piezoelectric transducer is made of Lithium niobate (LNO), polyvinylidene fluoride (PVDF), lead magnesium niobate-lead titanate (PMN-PT), transparent polymers, or transparent ceramics.

13. The transducer unit of claim 1 , wherein the transparent piezoelectric transducer and the backing layer are assembled within a transparent housing made of glass or acrylic or other transparent materials.

14. The transducer unit of claim 13 , wherein a parylene film is coated as an outermost layer covering the transparent housing, and wherein the parylene film is a matching layer and a waterproof layer of the transducer unit.

15. The transducer unit of claim 13 , wherein a gap between the transparent housing and an inner structure of the transparent piezoelectric transducer and the backing layer is filled with a transparent epoxy resin, wherein the transparent epoxy resin is transparent and provides protection and support.

16. A device for optical-acoustic imaging, comprising:

a light source configured to generate a light beam for providing an optical illumination to a target; and

a transducer unit comprising:

a transparent piezoelectric transducer having a concave surface and a flat surface, wherein the transparent piezoelectric transducer is configured to receive acoustic waves reflected from the target; and

an optical lens arranged to adhesively contact with and optically coupled to the flat surface of the transparent piezoelectric transducer along a vertical axis as a backing material;

wherein:

the optical illumination to the target is provided through the backing layer and the transparent piezoelectric transducer along the vertical axis; and

the concave surface is smooth and continuous with a radius of curvature determined based on a focal length for focusing the acoustic waves reflected from the target.

17. The device of claim 16 , wherein the flat surface and the concave surface are coated with transparent electrically conductive coatings; and the flat surface and the concave surface are physically and electrically separated for enabling measurement of the acoustic waves.

18. The device of claim 16 , wherein the transparent piezoelectric transducer and the optical lens have substantially similar acoustic impedances to minimize an acoustic impedance mismatch such that sensitivity of the device is improved.

19. The device of claim 16 , wherein the optical lens is a gradient-index (GRIN) lens designed for shaping the light beam as a focusing beam, a collimating beam, or a diverging beam by varying an index of refraction.

20. The device of claim 16 , wherein the transparent piezoelectric transducer is made of Lithium niobate (LNO), polyvinylidene fluoride (PVDF), lead magnesium niobate-lead titanate (PMN-PT), transparent polymers, or transparent ceramics.