STRUCTURALLY FLEXIBLE WAVEGUIDE

Abstract: A robust, inexpensive, and flexible apparatus that transports electromagnetic radiation to a receiving device. The apparatus includes a waveguide with a proximal and distal ends. A sheath formed from superelastic alloys is formed around the outer diameter of the waveguide. A housing is formed near the distal and proximal ends of the waveguide to provide structural support for the ends of the waveguide. Additionally, a connector is coupled to each housing to connect to a radiation source or a receiving device. The connector may be a FSMA connector and the apparatus may be used in a variety of medical and industrial applications.

Description: STRUCTURALLY FLEXIBLE WAVEGUIDE CROSS-REFERENCE TO RELATED APPLICATIONS The present invention claims the benefit of Provisional Patent Application No. 60/178,819, filed January 28, 2000. TECHNICAL FIELD The present invention relates generally to an apparatus for transmitting electromagnetic radiation, and more particularly, to a structurally flexible waveguide for transmitting electromagnetic radiation from a radiation source to a receiving device. BACKGROUND Electromagnetic radiation emitted from a radiation source, such as a laser, is often used in medical and industrial applications. The electromagnetic radiation can be delivered to an application site using a waveguide. When a waveguide is used during medical or industrial applications, the waveguide is commonly bent in various directions to maneuver around the application site. The bending of the waveguide can cause the waveguide to be damaged or break. Consequently, the electromagnetic radiation will be released and thus lost. Moreover, the released electromagnetic radiation can cause damage to the surface of the application site or bystanders. For example, the electromagnetic radiation can burn or scar tissue during a medical procedure. To minimize breakage, known waveguides use an armoring layer to strengthen the waveguide. The armoring layer can also be used to provide a barrier against the egress of harmful levels of electromagnetic radiation, when the waveguide breaks. However, the armoring layer increases the complexity, cost, and weight of the waveguide. The armoring layer also increases the resistance to motion of the waveguide around the application site. Therefore, a need exists for a waveguide that is flexible, inexpensive, and robust, and that can also transport radiation safely to an application site. SUMMARY In general, the invention is directed to an apparatus for transporting electromagnetic radiation from a radiation source to a receiving device. The apparatus includes a waveguide and a sheath formed from superelastic alloys that have high tensile strength and superelasticity. The sheath thus provides easy maneuverability with little resistance to motion around an application site. Accordingly, the invention is directed to an apparatus that includes a waveguide having a proximal end and a distal end. A sheath formed from superelastic alloys surrounds an outer surface of the waveguide and extends substantially between the distal and proximal ends. A housing surrounds the distal and proximal ends of the waveguide, and a connector is coupled to each housing. In another aspect, the invention is directed to a system for delivering electromagnetic radiation to an application site that includes a sheath formed from superelastic alloys that surround a waveguide. A radiation source is coupled to a proximal end of the waveguide, and a receiving device is coupled to the distal end of the waveguide. In yet another aspect, the invention is directed to a method of manufacturing a device for transporting electromagnetic radiation that includes providing a waveguide. The method also includes forming a sheath around the waveguide in which the sheath is made from superelastic alloys. In yet another aspect, the invention is directed to a method for delivering electromagnetic radiation from a radiation source to an application site that includes forming a sheath around a waveguide in which the sheath is made from superelastic alloys. The method also includes transmitting electromagnetic radiation through the waveguide. The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. DESCRIPTION OF DRAWINGS FIG. 1 illustrates a waveguide with a sheath in one embodiment. FIG. 2 illustrates a cross-sectional view of the waveguide and the sheath of FIG. 1. FIG. 3 illustrates an example of a radiation delivery system using the waveguide of FIG. 1. DETAILED DESCRIPTION In general, the invention is directed to an apparatus for transporting electromagnetic radiation from a radiation source to a receiving device. The apparatus includes a waveguide and a sheath formed around the outer surface of the waveguide. The sheath is preferably made from superelastic alloys that have high tensile strength and superelasticity. The sheath provides easy maneuverability with little resistance to motion around an application site. The apparatus also minimizes stress and compressive forces on the waveguide. Unless otherwise defined, all technical and scientific terms used herein have substantially the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although many methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable materials and configurations are described below. FIG. 1 illustrates a waveguide 1 having a sheath 5 formed around at least a portion of the outer surface of the waveguide 1 in an embodiment. In a preferred embodiment, the sheath 5 covers the entire outer surface of the waveguide 1. The waveguide 1 is preferably constructed for transmitting electromagnetic radiation from a radiation source 16, such as a laser, to a receiving device 28. Suitable receiving devices include a freehand laser cutting hand piece, a skin resurfacing scanner, a diamond scalpel with laser cautery, or other suitable devices. The waveguide 1 may be formed from hollow metal, a hollow silica-glass tube, a solid-core fiber, solid transparent glass, or solid transparent plastic. The waveguide 1 may be designed to transport radiation with wavelengths between 100 nm and 20 μm or more. The waveguide 1 may also include a polymer or halide and metallic layer deposited inside the waveguide 1. Referring again to FIG. 1, a housing 15 is formed near or around the proximal end 19 of the waveguide 1 and the proximal end 29 of the sheath 5. The housing 15 may be formed from steel, stainless steel, titanium, plastic extrusion tubing, braided metal tubing, corrugated or spiral wound metal flexible tubing. In one embodiment, the sheath 5 terminates inside the housing 15. The housing 15 may be used to secure the waveguide 1 such that the proximal end 19 of the waveguide 1 is rigidly secured. A bronze lock 48 may be used to further secure the waveguide 1 from lateral, axial, and rotational movement within the housing 15. A connector 30 is coupled to the housing 15. In one embodiment, the connector 30 may include a FSMA connector and includes a ferrule 43. The ferrule 43 may be formed from, for example, a metal, to join or bind the connector 30 to the radiation source 16. A shield 12, such as a molybdenum or copper shield, may be mounted at the tip of the ferrule 43. The shield 12 may include an opening (not shown) to allow focused radiation to enter into the waveguide. The shield 12, however, blocks all other radiation that is external to the opening to protect the waveguide from heating and damage. The shield 12 is preferably formed from a metal with high reflectivity and sufficient heat conduction. A grounding strap 50 may also be coupled to the housing 15. The grounding strap 50 is a safety device that prevents the radiation from harming bystanders or the application site. In one configuration, the source 16 is prevented from being turned on, when the strap 50 is not properly installed. Moreover, the source 16 is configured to shut off, when the strap 50 is removed or broken. A housing 35 may also be formed near or around the distal end 22 of the waveguide 1. The distal end 36 of the sheath 5 may terminate in a portion of the housing 35. The housing 35 may be formed from, for example, titanium or other suitable material. A connector 38 may be coupled to the housing. The connector 38 may include a FSMA connector. The connector 38 may also include a ferrule 53 similar to the ferrule 43 described above. The connector 38 is preferably adapted to connect to the receiving device 28. Similar to the housing 15, the housing 35 is preferably used to minimize the lateral movement of the waveguide 1. FIG. 2 shows a cross-sectional view of the sheath 5 formed around the waveguide 1. As shown, the sheath 5 preferably has a diameter that is slightly larger than the outer diameter of the waveguide 1. Further, the material of the sheath 5 is low friction. In this way, the waveguide 1 is able to move within the sheath 5, when the waveguide 1 is bent. One aspect described herein is the ability to move the waveguide 1 around an application site, with little resistance. Accordingly, the present inventors have discovered that the sheath 5 can be made from superelastic alloys that have high tensile strength and superelasticity. The superelastic alloys may include titanium, nickel, or other similar materials. Such alloys are commercially known as Nitinol ™ . These superelastic alloys withstand high elastic strains, and thus, a smaller bend radius. This smaller bend radius means that the apparatus of the present invention provides an increased degree of radial movement. It has been found that these superelastic alloys can be heat treated to retain or memorize a shape, after the sheath 5 and the waveguide 1 are exposed to heat. This means that the waveguide 1, that is initially straight, can be coiled or bent, and the sheath 5 will return the waveguide to its original straight shape. This also means that the sheath 5 will not distort or experience a permanent change in shape. Further, if the waveguide 1 does not return to its original straight shape, the optical properties of the waveguide 1 will degrade. Accordingly, using the preferred sheath 5, the waveguide can return to its original straight shape, and thus, will preserve the optical properties of the waveguide 1. It has also been found that certain superelastic alloys, such as Nitinol ™ , have a high melting temperature. This means that if the waveguide 1 breaks, any radiation passing through the waveguide 1 may be coupled in the sheath 5. The sheath 5, thus, operates to prevent the electromagnetic radiation from escaping. This means that the electromagnetic radiation will not burn through the sheath 5 and cause damage to the application site. The sheath may be painted, plated, or finished with a surface treatment to enhance visibility, cleanability, or esthetics. Further, the sheath 5 and waveguide 1 may be between 0.01 meters to 5 meters long. The housings 15, 35 may also include a layer of insulation 69 (FIG. 2) that surrounds the waveguide 1. The insulation layer 69 may be formed from glass, plastic, paper, epoxy, or paint. An example of a waveguide 1 in accordance with the present invention may conduct radiation at about 2 to 20 μm. The waveguide 1 may have an outer diameter of about 0.0423 inches and may have an inner diameter of about 0.021 inches. The inner diameter of the sheath 5 may be about 0.048 inches and the outer diameter of the sheath 5 may be about 0.060 inches. The sheath 5 may be made from superelastic alloys including nominally 54.2% titanium, nominally 55.8% nickel, and trace amounts of chromium, oxygen, and carbon. FIG. 3 illustrates an example of a delivery system using the preferred apparatus. In this example, the receiving device may be a free-cutting handpiece 90. In FIG. 3, the distal end 22 of the waveguide 1 passes through the housing 35 and terminates at the connector 38. The sheath 5 terminates, at its distal end 36, in the housing 35. The handpiece 90 may be coupled to the connector 38 using the ferrule 53. The cutting handpiece 90 may also include an optical fiber 95 with a lens 96 disposed at one end for focusing the radiation through the opening 99 on to the application site. In operation, electromagnetic radiation travels from the radiation source, such as a laser, and is transported through the waveguide to the optical fiber of the cutting handpiece. The electromagnetic radiation received in the fiber is then collimated or focused by the lens. The focused radiation then exits through the opening 99 on to the application site. ' The preferred apparatus for transporting electromagnetic radiation preferably includes a hollow bore-coated silica-glass waveguide surrounded by a sheath formed from superelastic alloys. The superelastic alloys are high in tensile strength and are superelastic. This means that the waveguide can be bent or moved without breaking. This is because the sheath prevents excessive stress and compressive forces from affecting the waveguide and potentially distorting its optical properties. Further, the sheath 5 is light weight as compared to known armoring. In this way, the preferred apparatus provides a light weight, reliable, and robust electromagnetic radiation transport system. Further, the preferred apparatus is versatile. The preferred apparatus includes a connector at the distal and proximal ends of the waveguide that can be adapted to connect to known receiving devices, such as freehand lasers, skin resurfacing scanners, and diamond scalpels with laser cautery. A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, a strain relief may be coupled to one or both sides of the housings 15, 35 to provide a gradual transition between the superelastic sheath and the rigid housings 15, 35. Accordingly, other embodiments are within the scope of the following claims.

Claims: WHAT IS CLAIMED IS: 1. An apparatus for transporting electromagnetic radiation from a radiation source to a receiving device, comprising: a waveguide having a proximal end and a distal end; 5 a sheath formed from superelastic alloys and surrounding an outer surface of the waveguide and extending substantially between the distal and proximal ends of the wave guide; a housing surrounding each of the distal and proximal ends of the waveguide; and o a connector coupled to each housing. 2. The apparatus of claim 1, wherein the waveguide comprises hollow glass silica. 3. The apparatus of claim 1 , wherein the waveguide further comprises a bore- coated hollow silica-glass tube. 5 4. The apparatus of claim 1 , wherein the waveguide comprises a polymer layer. 5. The apparatus of claim 2, wherein the apparatus comprises a halide layer and a metallic layer. 6. The apparatus of claim 4, wherein the superelastic alloys comprise one of titanium and nickel. 0 7. The apparatus of claim 1, wherein the sheath comprises Nitinol™. 8. The apparatus of claim 1, wherein the sheath comprises an inner diameter that is slightly larger than an outer diameter of the waveguide. 9. The apparatus of claim 1 , wherein the waveguide is operable to transport the electromagnetic radiation from the radiation source at a level of between 100 nm to 20 5 μm. 10. The apparatus of claim 1 , wherein the sheath comprises memory alloys, the memory alloys forming and maintaining a shape, when exposed to heat. 11. The apparatus of claim 4, wherein the superelastic alloys are operable to isolate the electromagnetic radiation. 12. The apparatus of claim 1, wherein each of the housings is formed from one of titanium, steel, and stainless steel. 13. The apparatus of claim 1, wherein each of the housings comprises a lock. 14. The apparatus of claim 1, wherein each of the housings comprises an insulation layer. 15. The apparatus of claim 1 , wherein the housing formed at the proximal end of the waveguide comprises a strain relief. 16. The apparatus of claim 1, wherein each of the connectors comprises a ferrule. 17. The apparatus of claim 1, wherein each of the connectors is adaptable to connect to one of the radiation source and the receiving device. 18. The apparatus of claim 1 , wherein each of the connectors comprises a FSMA connector. 19. The apparatus of claim 1, wherein the connector coupled to the housing at the proximal end of the waveguide further comprises a layer of molybdenum. 20. The apparatus of claim 1, wherein the waveguide is between .01 meters and 5 meters long. 21. The apparatus of claim 1 , wherein the waveguide comprises a polymer layer. 22. The apparatus of claim 1, wherein the radiation source comprises a laser. 23. The apparatus of claim 1 , wherein the receiving device comprises one of a freehand laser, a scanner, and a scalpel. 24. A system for delivering electromagnetic radiation to an application site, comprising: a sheath formed from superelastic alloys surrounding a waveguide, the waveguide having a proximal end and a distal end; a radiation source coupled to the proximal end of the waveguide; and a receiving device coupled to the distal end of the waveguide. 25. The system of claim 24, wherein the superelastic alloys comprise Nitinol™. 26. The system of claim 24, wherein the radiation source comprises a laser. 27. The system of claim 24, wherein the receiving device comprises one of a freehand laser, a scanner, and a scalpel. 28. The system of claim 24, wherein the radiation source transmits the electromagnetic radiation at a level between 100 nm and 20 μm. 29. The system of claim 24, wherein the receiving device comprises optics to focus the electromagnetic radiation at the application site. 30. The system of claim 24, wherein the application site is located on a patient. 31. The system of claim 24, wherein the sheath comprises a diameter that is slightly larger than an outer diameter of the waveguide. 32. A method of manufacturing a device for transporting electromagnetic radiation, comprising: providing a waveguide; and forming a sheath around the waveguide, the metal sheath including superelastic alloys. 33. The method of claim 32, further comprising connecting one end of the waveguide to a radiation source and connecting another end of the waveguide to a receiving device. 34. The method of claim 32, further comprising forming a housing around each end of the waveguide and terminating each end of the sheath inside the housing. 35. The method of claim 32, further comprising coupling a connector to each end of the waveguide. 36. The method of claim 32, wherein the forming step further comprises forming the sheath from Nitinol ™ . 37. The method of claim 32, further comprising exposing the sheath and waveguide to heat to shape the sheath and waveguide. 38. The method of claim 32, wherein the waveguide is formed from hollow glass silica. 39. The method of claim 32, wherein the providing step further comprises forming a polymer layer inside the waveguide. 40. A method for delivering electromagnetic radiation from a radiation source to an application site, comprising: forming a sheath around a waveguide, the sheath including superelastic alloys; and transmitting electromagnetic radiation through the waveguide. 41. The method of claim 40, wherein the superelastic alloys comprise Nitinol ™ . 42. The method of claim 40, wherein the radiation source comprises a laser. 43. The method of claim 40, wherein the receiving device comprises one of a freehand laser, a scanner, and a scalpel. 44. The method of claim 40, wherein the transmitting step further comprises causing the radiation source to transmit the electromagnetic radiation at a level between 100 nm and 20 μm. 45. The method of claim 40, wherein the receiving device comprises optics to focus the electromagnetic radiation at the application site. 46. The method of claim 40, wherein the application site is located on a patient. 47. The method of claim 40, wherein the forming step further comprises forming 5 ' the sheath with diameter that is slightly larger than an outer diameter of the waveguide. 48. An apparatus for delivering electromagnetic radiation from a radiation source to a receiving device, comprising: a waveguide; and o a Nitinol ™ sheath formed around the waveguide.

Inventors: CHOW WILLIAM WAI-CHUNG, GILLE HENRICK K, SCHIEFERSTEIN EDWARD S, CHOW, WILLIAM, WAI-CHUNG, GILLE, HENRICK, K., SCHIEFERSTEIN, EDWARD, S.
Applicants: CHOW WILLIAM WAI CHUNG, CLINICON CORP, GILLE HENRICK K, SCHIEFERSTEIN EDWARD S, CHOW, WILLIAM, WAI-CHUNG, CLINICON CORPORATION, GILLE, HENRICK, K., SCHIEFERSTEIN, EDWARD, S.
Application year: 2001
Main classification: G02B6
IPC codes: A61B17, A61B18, G02B6