Patent Application
20200061931
The invention relates to the field of laser surgery, and in particular to a method of attaching a fiber tip protective structure or standoff tip to a surgical laser fiber by welding the fiber tip protective structure to the fiber.
The method of the invention may be applied, by way of example and not limitation, to fiber tip protective structures such as the standoff soft tips described in the inventor's PCT Publication No. WO 2017/192869 and Provisional Patent Appl. Ser. No. 16/353,225, filed Mar. 14, 2019; each of which discloses standoff soft tips that serve to maintain a minimum distance between the distal end of the fiber and a stone during a laser lithotripsy procedure. Such standoff soft tips offer numerous advantages, including reduced fiber wear or erosion, protection of the interior surface of the scope through which the tip is inserted, and even facilitation of a Moses effect that reduces attenuation of the treatment laser and therefore allows use of a lower power laser and/or reduces treatment times.
A problem with fiber tip protective structures is that it is difficult to safely and economically secure the protective structures to the fiber. Conventional methods involve use of adhesives, crimping, or heat shrinking of the standoff tip, with or without an external crimp or heat shrink sleeve. However, these methods all have disadvantages. The disadvantages may include, depending on the method, high cost and low yield, or the presence of gaps, optical discontinuities, or thermal mismatches at the interface between the tip and the fiber. One potential solution, which is known to be generally safe and economical, is welding. However, welding has previously been disregarded as an attachment method for fiber tip protective structures because it is not apparent how one would achieve a weld when the interface to be welded is within the protective structure.
U.S. Pat. No. 6,282,349 (Griffin) includes a detailed discussion of the disadvantages of using adhesives to attach a quartz ferrule to a fiber, including contamination by the outgassing adhesive of the laser output lens and the possibility of sudden, explosive failure of the fiber termination as well as low yield if the viscosity of the adhesive is increased to avoid outgassing or the ferrule is countersunk to move the adhesive away from the end of the fiber. In addition, the Griffin patent discusses the disadvantages of crimping the ferrule directly to the fiber, including lowered connector mass and incompatibility with surgical laser interlocks. Griffin's solution is to insert the ferrule into a cylindrical beam block having an extension of the polymer-clad buffer portion of the fiber extending outside the ferrule, and to crimp the extension onto the fiber.
The present invention, in contrast, not only does not require adhesives, but also does not require any additional structures, including heat sleeves or beam blocks of the type disclosed by Griffin. Instead, the present invention enables welding of the protective structure directly to the fiber tip, without any additional cost-increasing and yield-lowering manufacturing steps.
It is an objective of the invention to provide a way to attach a protective structure or standoff tip to a surgical laser fiber over an area that extends around the circumference of the fiber, without gaps or discontinuities, resulting in a product that is safe and economical to produce.
It is a further objective of the invention to provide a method of welding a protective structure or standoff tip to a surgical laser fiber.
The method of the invention may be applied to any standoff or protective tip configuration, including those described in the inventor's PCT Publication No. WO 2017/192869 and Provisional Patent Appl. Ser. No. 62/648,108.
In a preferred embodiment of the invention, a length of polymer tubing that will form the standoff or fiber tip protective structure is positioned relative to the section of fiber to which the tubing is to be attached. The polymer tubing is made of a material having high transmissivity to laser radiation. One or both of the respective surfaces of the tubing and the fiber at the interface between the tubing and the fiber is made of a material that absorbs radiation and therefore heats up when laser radiation is directed through the tubing to weld the tubing to the fiber.
A circumferential weld is achieved by positioning the fiber and polymer tubing in a lathe or similar rotating machine, and holding the fiber and tubing in contact synchronously rotating the tubing and the fiber and applying the weld energy through the polymer tubing. Heating of the materials is monitored by detecting changes in transmission and reflection of ambient lighting resulting from heat-induced changes in the optical properties of the materials to which the welding energy is applied.
Although the tubing of the illustrated embodiment is described as a length of polymer tubing, which forms a soft tip protective structure, it is within the scope of the invention to utilize tubing or cylindrical structures that are made of materials other than polymers, so long as a portion of the structure can be made transparent to laser radiation and, preferably, will absorb heat so that it can be fused to the fiber.
Throughout the following description and drawings, like reference numbers/characters refer to like elements. It should be understood that, although specific exemplary embodiments are discussed herein there is no intent to limit the scope of present invention to such embodiments. To the contrary, it should be understood that the exemplary embodiments discussed herein are for illustrative purposes, and that modified and alternative embodiments may be implemented without departing from the scope of the present invention.
As illustrated in
During welding, a waveguide 33 is positioned so that a laser beam 37 transmitted through the waveguide will irradiate a section of the overlapped polymer materials. The laser is then activated to heat the area 36 to be welded as the tubing and fiber are rotated. Alternatively, the laser beam may be directed at the weld point by a movable mirror, or by a lens system, or by physically moving the laser source or the parts to be welded so that the beam may be properly positioned along an axis of the fiber and tubing during welding.
Heating of the materials is monitored by monitoring transmission and reflection of ambient lighting. As the materials are heated, their optical properties change. The resulting thermal lensing effect allows the welding operator or optical sensors to visualize the temperature of the melting materials. When the materials reach a temperature sufficient to allow fusion, the laser is deactivated to enable the parts to cool. The parts may then be inspected under various lighting conditions to verify a complete weld.
Although a specific protective structure is illustrated, the fiber tip protective structures to which the method of the invention may be applied include caps, ferrules, sleeves, sheaths, standoff catheters, or any other protective structures that are placed over and fixed to the distal or treatment end a surgical laser optical fiber, for purposes that are not limited to protection of the fiber tip or scope or to any particular type of surgical applications. Accordingly, the length of tubing that forms the protective structure is not limited to a particular material, and in particular is not limited to polymers.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/720,331, filed Aug. 21, 2019, and incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62720331 | Aug 2018 | US |
