Abstract:
A novel optical fiber, and a method for its production, having a diffuser portion and continuous unitarily-constructed outer sleeve, which is adapted for the transmission of light to a treatment locale. More particularly, a medical instrument has an optical fiber including a diffuser portion at a distal end wherein an alignment sleeve for the optical fiber extends uninterruptedly in a single piece from a connector for a laser light source to at least the distal end of the core of the optical fiber.

Description:
This divisional application claims priority to U.S. patent application Ser. No. 10/315,440 filed Dec. 10, 2002 now U.S. Pat. No. 6,718,089, which claims priority to U.S. patent application Ser. No. 09/785,571 filed Feb. 16, 2001, now U.S. Pat. No. 6,522,806. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates, in general, to a novel optical fiber having a diffuser portion and continuous unitarily-constructed outer sleeve, which is adapted for the transmission of light to a treatment locale. More particularly, the invention relates to a medical instrument with an optical fiber including a diffuser portion at a distal end wherein an alignment sleeve for the optical fiber extends uninterruptedly in a single piece from a connector for a laser light source to at least the distal end of the core of the optical fiber. 
   Currently, surgeons frequently employ medical instruments which incorporate laser technology in the treatment of benign prostatic hyperplasia, or as commonly referred to as BPH. BPH is a condition of an enlarged prostate gland, in which the gland having BPH typically increases in size to between about two to four times from normal. The lasers which are employed by the surgeons to treat this condition must have durable optical fibers that distribute light radially in a predictable and controlled manner, and must also be capable of bending without breaking, whereby small-sized or slender optical fibers offer an additional advantage to the surgeon. 
   An optical fiber which is adapted to be employed for this purpose typically contains a glass core surrounded by cladding, a buffer layer, and an outer alignment sleeve. The cladding protects the inherently weaker glass core by imparting a mechanical support to the core. The cladding also ordinarily possesses an index of refraction which is lower than that of the core in order to block light transmitted through the optical fiber from emerging radially from the core. Although optical fibers which are utilizable for such surgical procedures and treatments are widely known and successfully employed, the present invention is designed to provide further significant improvements and advantages over the state-of-the art. 
   2. Discussion of the Prior Art 
   An optical fiber with a diffuser portion for diffusing light emitted at an end thereof is disclosed in Esch U.S. Pat. No. 5,754,717 as shown in  FIG. 1  of this application, which patent is commonly assigned to the present assignee, and the disclosure of which is incorporated herein by reference. There is illustrated an optical fiber leading end  10  having a diffuser portion  12  comprised of the stripped core of a typical optical laser, an optical coupling layer, and an outer or alignment sleeve  14 . The optical coupling layer, replacing a part of the cladding and the buffer layer of the optical fiber, has an index of refraction exceeding that of the core so as to draw the light out of the core using well-known physical principles. The alignment sleeve is abraded, or roughened, in order to conduct light from the optical coupling layer to the exterior, while heat staking or ultrasonic welding is used to apply or attach the portion of  14   a  of the outer sleeve  14  covering the diffuser tip to a further separate portion  14   b  of the sleeve located towards the end of the optical fiber. 
   In essence, the method of forming the diffusion portion of the optical fiber illustrated in  FIG. 1  representing the Esch patent, necessitates the presence of a weld joint  16  near the distal end of the remaining cladding. Producers of optical fibers with diffuser portions intended for this or similar surgical purposes are required to ensure an adequate mechanical strength of the fiber for the intended application, and in which the weld joint can result in a stress concentration reducing the strength of the optical fiber. It is also possible that silicone or adhesive from the optical coupling layer may contaminate the area of the sleeve junction during assembly, thereby weakening the weld joint. While the weld joint is deemed to be of adequate strength for most surgical applications, designers would like to use smaller-sized optical fibers. As the diameter of optical fibers become smaller, the degradation in strength of the optical fiber caused by the presence of the weld joint becomes more pronounced and resultingly important. The smaller diffusers can readily break or become detached at the weld joint; whereas the weld seam at the weld joint can catch on instruments and interfere with the medical procedure, thereby creating a nuisance, if not an operating danger for the surgeon. 
   Other publications which disclose various constructions and types of optical fiber arguments which may be applicable to surgical procedures and treatments employing laser illumination are widely known in the technology. 
   Anderson et al. U.S. Pat. No. 5,814,041 pertains to an optical radiator and laser fiber in which the distal or leading end sleeve portion of the optical fiber is attached to a second sleeve portion so as to form a weld or contact seam therebetween. 
   Evans et al. U.S. Pat. No. 5,802,229 discloses a fiber optic radiation system which, similar to Esch, does not provide for a continuous, unitarily constructed outer sleeve for the optic fiber. 
   Bruce U.S. Pat. No. 5,534,000 discloses a laser fiber apparatus wherein the leading or ablation end of an optic fiber is provided with a relatively short outer tube element so as form an essentially non-continuous sleeve surface providing a seam-like joint or step. 
   Similarly, Doiron et al. U.S. Pat. Nos. 5,269,777 and 5,196,005; and McCaughan, Jr. U.S. Pat. Nos. 4,693,556 and 4,660,925, disclose various types of optical fibers with light diffusers or similar structures; however, none of which evidence the continuous single-piece outer sleeve of seamless length as provided for by the present invention, nor the method of forming thereof. 
   SUMMARY OF THE INVENTION 
   Accordingly, the design of an optical fiber with a diffuser portion including an outer sleeve wherein the weld joint is eliminated is -highly advantageous in constructing the sleeve of the optical fiber extending as one continuous, uninterrupted or unitary piece from the connector for a light source to the distal end of the core. 
   Pursuant to the invention, a medical instrument comprises a source for a laser light wherein an optical fiber with a diffuser portion at its distal end has the outer sleeve of the optical fiber constituted of a continuous unitarily-constructed tube extending from the connector for the laser-light source to at least the distal end of the core in the optical fiber. The sleeve of the optical fiber also contacts and supports the optical fiber at the leading or light emitting distal end thereof. 
   Accordingly, it is an object of the present invention to provide a method of producing an optical laser fiber arrangement in which the outer tubular sleeve encompassing the fiber core is of a continuous, unitarily constructed and seamless tubular structure. 
   Another object of the present invention is to provide a medical instrument incorporating an optical laser fiber produced in accordance with the inventive method for forming the optical fiber portion of the instrument. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference may now be made to the following detailed description of preferred embodiment of the invention, taken in conjunction with the accompanying drawings; in which: 
       FIG. 1  illustrates a longitudinal sectional view of an optical fiber utilizing the diffuser portion as shown in the Esch U.S. Pat. No. 5,754,717, representative of the prior art; 
       FIG. 2  illustrates a schematic representation of a laser device utilizing the optical fiber pursuant to the present invention; 
       FIG. 3  illustrates a diagrammatic perspective view of an optical fiber assembly incorporating an embodiment of the present invention; 
       FIG. 4  illustrates a longitudinal sectional view of the inventive optical fiber utilizing a diffuser portion, showing as represented from the interior to the exterior thereof, a core, an optical coupling layer, and an outer sleeve contacting the core distal to the diffuser portion; 
       FIG. 5  illustrates a fragmentary sectional view showing the annulus material containing a light-scattering component; 
       FIG. 6  illustrates a longitudinal sectional view showing the annulus assembled to the core prior to implementing the tipping step in an optical fiber utilizing the inventive diffuser portion, and 
       FIG. 7  illustrates a longitudinal sectional view of an embodiment of an optical fiber utilizing the inventive diffuser portion showing, as represented from the interior to the exterior, a core, an optical coupling layer, and an outer sleeve contacting the core distal to the diffuser portion. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring in detail to the drawings, for purposes of this description, “proximal” refers to a section on the inventive optical fiber  28  closer to a source of light energy  22 , and “distal” refers to a section on the optical fiber which is further away from the source of light energy  22 . 
   Illustrated schematically in  FIG. 2  is a medical instrument  20  for diffusing light from an optical fiber  28 . The medical instrument  20  includes a source of light energy  22 , preferably a laser; and wherein the optical fiber  28  connects into the source of light energy  22  through the intermediary of a connector  18  which is attached to a connection port  24  leading to a diffuser portion  19  of the optical fiber. A typical connector and connection port of this kind which can be utilized for the medical instrument  20  is described in Evans et al. U.S. Pat. No. 5,802,229, while a typical laser employable for the medical instrument  20  is the Optima laser which will be sold by Ethicon Endo-Surgery in Cincinnati, Ohio. The optical fiber  28  with the attached connector  18  can be provided and sold separately from the source of light  22 , as an optical fiber assembly  29 , as represented in  FIG. 3  of the drawings. 
   A typical optical fiber  28  according to one embodiment of the present invention, including diffuser portion  19  and a proximal light-transmitting portion  34  is shown in  FIG. 4 . In a light-transmitting portion  23  of the optical fiber  28 , a cladding  32  and the proximal portion  34  of a sleeve  38  radially surround the proximal portion  30  of a core  31 . The optical fiber  28  may also have a buffer layer  42  arranged to extend circumferentially between the cladding  32  and the sleeve  38 . The material used to form the cladding  32  has an index of refraction lower than the index of refraction of the material-used to create the core  31  so as to contain the light within the core  31 . The core  31 , in addition to its proximal portion  30 , extends through a distal portion  36  to the distal end  52  thereof. The distal portion  36  of the core  31  which is employed to diffuse light, is surrounded by an optical coupling layer  40  and the distal portion  44  of the sleeve  38 . There is no interruption, discontinuity, or weld joint on the sleeve  38  inasmuch as the proximal portion  34  of the sleeve  38  and the distal portion  44  of the sleeve  38  are two segments of one continuous unitarily constructed sleeve  38 . The sleeve  38  can extend distally past the distal end  52  of the core  31  and may be configured to penetrating tip  50 . The sleeve  38 , as mentioned, is constituted of one continuous piece, preferably consisting of perfluoroalkoxy impregnated with barium sulfate. 
   A material having an index of refraction higher than the. index of refraction of the core  31  forms the optical coupling layer  40 , wherein UV50 Adhesive, available from Chemence, Incorporated, in Alpharetta, Ga., can be used to produce the optical coupling layer  40 . 
   A light-scattering component  48  which is filled with a light-scattering material and located on the distal face  52  of the core  31  can reflect light back into the core  31  so as to provide a more even or uniform light distribution, whereby alexandrite can be employed as the light-scattering material for component  48 . In addition to its light-scattering properties, the material fluoresces in a temperature-dependent manner upon being stimulated by light, with this property adapted to be used to measure temperature in tissue in proximity to the diffuser portion  19 . The same adhesive which is employed for the optical coupling layer  40  can suspend the alexandrite particles therein and can serve as the base material for the light-scattering component  48 . 
   As illustrated in, respectively,  FIGS. 4 and 7 , utilizing the light-scattering component  48 , the sleeve  38  is shaped to extend distally past the light-scattering component  48  and resultingly forms a pointed penetrating tip  50 . 
   During operation of the medical instrument  20 , light generated by the source of light energy  22  travels through the core  31  to the diffuser portion  19 . There, in the embodiment of the invention illustrated in  FIG. 4 , light energy emerges from the core  31  to the optical coupling layer  40  because of the optical coupling layer having a higher index of refraction. The distal portion  44  of the sleeve  38  which surrounds the optical coupling layer  40 , collects the light from the optical layer  40 , employing the abrasions formed on the inner surface of the distal portion  44  of the sleeve  38 . The sleeve  38  preferably uses barium sulfate particles scattered within the sleeve  38  to direct light energy evenly outwards towards the tissue. Light energy reaching the light-scattering component  48  is reflected back towards the core  31  by the alexandrite particles in the light-scattering component  48 . Moreover, the fluorescent properties of the alexandrite particles, when stimulated by light energy of the proper wavelength, can determine the temperature of surrounding tissues employing methods which are known in the art. The penetrating tip  50  is capable of piercing tough tissue in order to assist medical procedures. 
   The inventive sleeve  38  has no weld joints or discontinuities in the outer diameter extending from the proximal end of the penetrating tip  50  to the connector  18  which conceivably tend to weaken the optical fiber  28 , or which may detrimentally catch or drag the optical fiber  28  so as to displace the latter while in use. When using the optical fiber  28 , surgeons or medical practitioners often need to bend it to successfully locate the fiber in the body of a patient. The optical fiber  28  and the associated sleeve  38  can withstand more bending than optical fibers with sleeves which have weld lines or discontinuities formed in the outer diameter thereof proximal to the penetrating tip  50 . 
   Method of Forming the Optical Fiber 
   In order to produce an optical fiber according to the invention as shown in  FIG. 4 , there can be modified an optical fiber  28  with its associated sleeve  38 . First, a sleeve  38  is provided which is approximately as long as the optical fiber to be used, and preferably long enough to extend from the connector  18  (shown in  FIG. 3 ) past the distal face  52  of the core  31 . Thereafter, the inner surface of the distal portion  34  of the sleeve  38  is abraded. Different methods can be used to abrade, texture, or roughen the inner surface, such as, brushing with a small brush, roughening with a small tool, or pressing against a mandrel to mold in rough areas, can all be employed in order to create a rough inner surface. The roughening process can be implemented while the sleeve  38  is a separate piece before its assembly with the other components of the optical fiber  28 , or it can be effected subsequent to assembly. In case the roughening process is performed after assembling the sleeve to the fiber, the sleeve  38  is slid over the buffer layer  42  so as to extend the sleeve  38  distally beyond the distal end of the buffer layer  42  and core  31 . Moving the sleeve  38  distally beyond the distal end of the buffer layer  42  and core  31  will expose the interior of the sleeve  38  so that it can be easily abraded. 
   After abrading, in order to prepare the optical fiber  28  for assembly, the distal portion  36  of the core  31  is exposed by stripping away the buffer layer  42  and the surrounding cladding  32 . Leaving the cladding  32  so as to extend distally beyond the end of the buffer layer  42  in a stepped manner, as shown in  FIG. 4 , reduces the formation of any stress concentration points. 
   In order to make the light-scattering component  48 , a mix of alexandrite particles and uncured adhesive, preferably in a ratio of 2.5 to 1 of alexandrite to adhesive by weight, is conveyed into a tube material used for annulus  46 , and having an inner diameter which is equal to the outer diameter of the core  19 . The annulus material should be long enough to extend well beyond the end of the sleeve  38  upon assembly. The mix of uncured light-scattering component material is an axial length of annulus material  46  containing the light-scattering component  48 , as shown in  FIG. 5 . 
   The sleeve  38  is then slid over the prepared core  31  and buffer layer  42  until the sleeve  38  extends beyond the distal face  52  of the core  31 . Uncured adhesive  53  is then applied to the empty volume or space left by the buffer layer  42  and cladding  32  having been previously removed. The sleeve  38  is moved so as to extend the core  31  slightly beyond the end of the sleeve  38 , and the length of annulus material containing the uncured light-scattering component material is then fitted over the end of the exposed core  19 . The light-scattering component material should abut the distal face  52  of the core  19  and a small length of annulus material should surround the core  19  near its distal face  52 . The core  31 , the light-scattering component material, and a length of annulus material are then recessed or withdrawn into the sleeve  38 , leaving a length of annulus material extending beyond the distal face  52  of the core  31 , and substantially the same distance beyond face  52  as sleeve  38 , illustrated in  FIG. 6 . In case no light-scattering component  48  is needed, the length of annulus material without the light-scattering component  48  is positioned around the core  31  near its distal face  52   
   In an optional step, there may be removed any air bubbles which may be present in the optical coupling. layer  40 . The distal end of the optical fiber  28  with the distal face  52  of the core  31  is held down while being heated to allow the adhesive that will form the optical coupling layer  40  to flow towards the distal end under the effect of gravity. This step will assist in eliminating air from the optical coupling layer  40  in order to allow it to transmit light from the core  31  more efficiently, whereby, for instance, heat can be applied with a heat gun. 
   With the annulus material in place, the adhesive and the light-scattering component material are cured to form the optical coupling layer and light-scattering component  48  whereby pursuant to one embodiment of the invention, the adhesive can be cured by means of ultraviolet light. 
   The penetrating tip  50  is formed by placing the distal end of the optical fiber into a mold and heating it to melt and fuse the sleeve  38  and the annulus  46  into one piece, producing the embodiment shown in  FIG. 4 , leaving a small air pocket  51  in conjunction with the light-scattering component  48 . 
   In one embodiment of the invention, both the annulus  46  and the sleeve  38  are made of the same material and formed into one piece so that the annulus  46  becomes a part of the sleeve  38  once the parts are melted and fused. The annulus  46 , as a portion of the sleeve  38 , contacts the core  31  at the distal portion  36  of the core. It also contacts and aligns the light-scattering component  48  upon use of the light scattering component  48 . The penetrating tip  50  being formed on the optical fiber  28 , referred to as tipping, completes the diffuser portion  19  on the optical fiber  28 . 
   Another method of forming an embodiment of the optical fiber pursuant to the invention produces the configuration shown in  FIG. 7 . In order to produce this embodiment, the cladding  32  and the buffer layer  42  are first stripped from the core  31 , as described in the previous method. The distal portion  44  of the sleeve  38  is abraded as before. The sleeve  38  is then displaced so as to extend past at least the distal face  52  of the core  31 . Using an adhesive which is curable into an optical coupling layer  40 , the void left by the removed buffer layer  42  and cladding  32  is then filled. If the light-scattering component  48  is used, the light-scattering component  48  is pushed through the uncured adhesive to the distal face  52  of the core  31 . In order to close the end of sleeve  38 , the sleeve end is heated in a mold which forces the sleeve  38  radially towards the core  31  to thereby form the embodiment shown in  FIG. 7 , with the sleeve  38  connecting the core  31  and the light-scattering component  48 , and air pocket  51  formed within tip  50 . The adhesive is cured into the optical coupling layer  40 , whereby in one embodiment of the invention, ultraviolet light can be used to cure the adhesive. 
   It is readily apparent that equivalent structures may be substituted for the structures illustrated and described herein and that the described embodiments of the invention are not limited to those elucidated. As one example of an equivalent structure which may be used, the optical coupling layer  28  can comprise a substance filled with light-scattering particles, which if employed eliminates need to abrade the inner surface of the sleeve  38 . 
   While the invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing form the spirit and scope of the invention.