Array transducer-based side-scanning photoacoustic-ultrasonic endoscope

Patent metadata

Field	Value
Publication number	US-10905397-B2
Application number	US-201815872414-A
Country	US
Kind code	B2
Filing date	Jan 16, 2018
Priority date	Feb 15, 2017
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

A photoacoustic-ultrasonic (i.e. dual mode) endoscope includes: an optical fiber; a light diffuser configured to diffuse a laser beam delivered through the optical fiber to a target point of an object to be examined; and an array transducer through which the diffused laser beam passes and configured to generate ultrasonic waves or detect ultrasonic waves generated in the object to be examined.

First claim

What is claimed is:

1. A photoacoustic-ultrasonic endoscope comprising:
an optical fiber placed along an inside of an insertion hose of an endoscope probe;
a light diffuser provided so that a laser beam guided and emitted from the optical fiber is diffused and finally emitted toward a target point of an object to be examined through a partial surface allocated at a side of the light diffuser in such a way that the partial surface does not overlap an original propagation direction of the laser beam emitted from the optical fiber; and
a one or two-dimensional optically-transparent array transducer that passes the diffused laser beam and also fires ultrasonic pulses and detects ultrasonic waves generated from the object to be examined by being disposed on the partial surface of the light diffuser,
wherein an outer surface other than the partial surface of the light diffuser is coated or surrounded by a light reflecting layer that reflects back a light scattered from the light diffuser into an interior of the light diffuser so that scattered and reflected light can be eventually emitted outside only through the partial surface by the light diffuser.

2. The photoacoustic-ultrasonic endoscope of claim 1 , wherein the laser beam diffused by the light diffuser passes through an entire area of the array transducer.

3. The photoacoustic-ultrasonic endoscope of claim 1 , further comprising an acoustic matching layer covering at least a part of an outer surface of the array transducer and comprising a material through which light is transmitted.

4. The photoacoustic-ultrasonic endoscope of claim 3 , wherein the material of the acoustic matching layer is made to comprise polymethylpentene (TPX).

5. The photoacoustic-ultrasonic endoscope of claim 1 , wherein a light emitting area (LEA) where the diffused laser beam escapes from the array transducer and an ultrasonic sensor area (USA) where the array transducer senses ultrasonic waves overlap each other.

6. The photoacoustic-ultrasonic endoscope of claim 1 , wherein the light diffuser has a shape in which the partial surface is convex outward.

7. The photoacoustic-ultrasonic endoscope of claim 1 , wherein a reduced scattering coefficient (μ s ′) of the light diffuser is equal to or greater than 0.1 cm −1 and equal to or less than 1.0 cm −1 or
a distance from a distal end of the optical fiber from which the laser beam is emitted to the center of the optical diffuser coincides with a transport average free path value of the optical diffuser.

8. The photoacoustic-ultrasonic endoscope of claim 1 , wherein the light diffuser comprises at least one of polypropylene, plastic resin, ground glass, and engineered diffuser.

9. The photoacoustic-ultrasonic endoscope of claim 1 , wherein a distal end of the optical fiber from which the laser beam is emitted is inserted into the light diffuser to a certain depth.

10. The photoacoustic-ultrasonic endoscope of claim 1 , wherein the light diffuser has an empty space, and an end point of the optical fiber is located in the empty space.

11. The photoacoustic-ultrasonic endoscope of claim 10 , wherein the empty space has a conical shape.

12. The photoacoustic-ultrasonic endoscope of claim 1 , further comprising a light reflection mirror surrounding an outer surface of the light diffuser, wherein the light reflection mirror has an opened portion corresponding to the partial surface in order to emit the laser beam diffused by the light diffuser only through the partial surface.

13. The photoacoustic-ultrasonic endoscope of claim 1 , wherein the array transducer comprises:
a piezoelectric layer having a predetermined thickness;
a plurality of first electrodes located on a first surface of the piezoelectric layer a one-dimensional (1D) or two-dimensional (2D) array; and
a plurality of second electrodes located on a second surface of the piezoelectric layer opposite to the first surface and in parallel to the plurality of first electrodes,
wherein the array transducer passes the laser beam through at least a partial area.

14. The photoacoustic-ultrasonic endoscope of claim 13 , further comprising a transparent backing layer between the light diffuser and the piezoelectric layer.

15. The photoacoustic-ultrasonic endoscope of claim 13 , wherein the plurality of first electrodes and the plurality of second electrodes are transparent electrodes.

16. The photoacoustic-ultrasonic endoscope of claim 15 , wherein each of the plurality of first electrodes and the plurality of second electrodes comprises any one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In 2 O 3 ), Ge-doped In 2 O 3 (IGO), and aluminum-doped zinc oxide (AZO).

17. The photoacoustic-ultrasonic endoscope of claim 13 , wherein the plurality of first electrodes and the plurality of second electrodes comprise non-transparent electrodes.

18. The photoacoustic-ultrasonic endoscope of claim 17 , further comprising a light reflection layer between the plurality of second electrodes and the light diffuser.

19. A photoacoustic-ultrasonic endoscope comprising:
an optical fiber placed along an inside of an insertion hose of an endoscope probe;
a light diffuser provided so that a laser beam guided and emitted from the optical fiber is diffused and finally emitted toward a target point of an object to be examined through a partial surface allocated at a side of the light diffuser in such a way that the partial surface does not overlap an original propagation direction of the laser beam emitted from the optical fiber: and
a one or two-dimensional optically-transparent array transducer that passes the diffused laser beam and also fires ultrasonic pulses and detects detect ultrasonic waves generated from the object to be examined by being disposed on the partial surface of the light diffuser,
wherein an outer surface other than the partial surface of the light diffuser is coated or surrounded by a light reflecting layer that reflects back a light scattered from the light diffuser into an interior of the light diffuser so that scattered and reflected light can be eventually emitted outside only through the partial surface by the light diffuser,
wherein a light emitting area (LEA) where the diffused laser beam escapes from a scanning head and an ultrasonic sensor area (USA) of the array transducer overlap each other.

Assignees

• Ulsan Nat Inst Science & Tech Unist

Inventors

• Yang Joon Mo
• Kim Chae Un

Classifications

• A61B8/5246

  combining images from the same or different imaging techniques, e.g. color Doppler and B-mode · CPC title

• A61B8/5269

  involving detection or reduction of artifacts · CPC title

• A61B8/483

  involving the acquisition of a 3D volume of data · CPC title

• A61B8/12

  in body cavities or body tracts, e.g. by using catheters · CPC title

• A61B8/4494 Primary

  characterised by the arrangement of the transducer elements · CPC title