Optical fiber and an underwater shockwave generating device employing the same

Patent metadata

Field	Value
Publication number	US-9433466-B2
Application number	US-201113880530-A
Country	US
Kind code	B2
Filing date	Jul 27, 2011
Priority date	Oct 19, 2010
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

An optical fiber is provided which has good laser beam condensation efficiency and is highly resilient, and a shockwave generating device employing same. An optical fiber is employed in an underwater shockwave generating device which projects a laser beam underwater and generates an underwater shockwave. The optical fiber includes a main body part, and a laser convergence part that is disposed upon a leading end thereof. The laser convergence part is configured so as to exhibit an approximately frustum shape wherein the diameter of the leading end is narrower than the diameter of the base end, and such that an interior angle with respect to a radial direction of a lateral face of an axial cross-section gradually decreases toward the front thereof.

First claim

The invention claimed is:

1. An optical fiber for use in an underwater shockwave generating device that generates an underwater shockwave by irradiating a laser beam underwater, said optical fiber comprising;
a linear main body part and a laser beam convergence part disposed on a front end thereof,
wherein the laser beam convergence part has a central longitudinal axis and a radius extending from the central longitudinal axis to an outer circumference of the laser beam convergence part gradually decreases toward a front end of the laser beam convergence part,
wherein the laser beam convergence part has an approximate solid truncated cone shape where a leading end has a planar surface perpendicular to the axis,
wherein an interior angle with respect to a radial direction of a lateral face of an axial cross-section of the laser beam convergence part continuously or non-continuously and gradually decreases toward the front, and
wherein an outer surface of the laser beam convergence part is configured to be a mirror surface by mirror finishing.

2. An optical fiber according to claim 1 , wherein the lateral side of an axial cross-section of the laser beam convergence part is formed of a plurality of straight segments.

3. An optical fiber according to claim 1 , wherein the lateral side of an axial cross-section of the laser beam convergence part has a curved segment shape.

4. An optical fiber according to claim 1 , wherein the lateral side of an axial cross-section of the laser beam convergence part is formed of a combination of straight and curved segments.

5. An underwater shockwave generating device, comprising;
the optical fiber of claim 1 ,
a reflector having concave surface at a front end,
a blocking membrane closing an opening of the concave surface,
a liquid charged between the concave surface and the blocking membrane,
wherein the reflector has the concave surface of an ellipsoid of revolution shape in which a major axis is a rotating axis, and a centered hole for the optical fiber to communicate with the concave surface formed on the major axis,
wherein the optical fiber is fixed to the reflector so as a front end of the laser beam convergence part is located on a focal point of the concave surface.

6. An underwater shockwave generating device according to claim 5 , wherein a length of the laser beam convergence part is the same as or shorter than a diameter of the optical fiber.

7. An optical fiber according to claim 1 , wherein said underwater shockwave generating device further comprises a reflector having a concave surface at a front end; wherein said membrane closes the front end of the concave, and wherein said liquid is charged in the concave surface.

8. An optical fiber according to claim 1 , wherein a length of the laser beam convergence part is the same as or shorter than a diameter of the optical fiber.

9. An underwater shockwave generating device, comprising;
an optical fiber,
a reflector having a concave surface at a front end,
a blocking membrane closing an opening of the concave surface,
a liquid charged between the concave surface and the blocking membrane,
wherein the reflector has the concave surface of an ellipsoid of revolution shape in which a major axis is a rotating axis, and a centered hole for the optical fiber to communicate with the concave surface formed on the major axis,
wherein the optical fiber comprises a linear main body part and a laser beam convergence part disposed on a front end thereof,
wherein the optical fiber is fixed to the reflector so as a front end of the laser beam convergence part is located on a focal point of the concave surface,
wherein an interior angle with respect to a radial direction of a lateral face of an axial cross-section of the laser beam convergence part continuously or non-continuously and gradually decreases toward the front, and
wherein an outer surface of the laser beam convergence part is configured to be a mirror surface by mirror finishing.

Assignees

• Takayama Kazuyoshi
• Yamamoto Hiroaki
• Shimokawa Hiroaki
• Univ Tohoku

Inventors

• Takayama Kazuyoshi
• Yamamoto Hiroaki
• Shimokawa Hiroaki

Classifications

• A61B2018/263

  the conversion of laser energy into mechanical shockwaves taking place in a liquid · CPC title

• A61B2017/22024

  with a part reflecting mechanical vibrations, e.g. for focusing · CPC title

• A61B17/22012 Primary

  in direct contact with, or very close to, the obstruction or concrement (for removing obstructions in blood vessels by laser A61B18/245) · CPC title

• A61B2017/22025

  applying a shock wave (A61B2017/22091 takes precedence) · CPC title

• G02B6/262 Primary

  Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements · CPC title