Patent Publication Number: US-2021173143-A1

Title: Optical fiber for transmitting both an illumination light and a laser light beam

Description:
PRIORITY CLAIM 
     This application claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 62/943,331 titled “OPTICAL FIBER FOR TRANSMITTING BOTH AN ILLUMINATION LIGHT AND A LASER LIGHT BEAM,” filed on Dec. 4, 2019, whose inventors are Chenguang Diao, Ronald T. Smith and Alireza Mirsepassi, which is hereby incorporated by reference in its entirety as though fully and completely set forth herein. 
    
    
     DESCRIPTION OF THE RELATED ART 
     In a wide variety of medical procedures, laser light is used to assist the procedure and treat patient anatomy. For example, in laser photocoagulation, a laser probe is used to cauterize blood vessels on the retina. Some probes include a fiber optic cable containing one fiber for delivering laser light to the surgical site, and a separate fiber for delivering illumination light at the same time during an eye surgery procedure, for instance, a bimanual operation. In such cases, one of the two fibers is connected to a laser source to deliver the laser beam, and the other fiber is connected to an illumination source for illumination light, and the two fibers are combined and tightly packed within a tube of the fiber optic cable to minimize the size of the fiber optic cable and, therefore, the size of the probe tip where the fiber optic cable is placed. Using a probe tip with a smaller gauge size is advantageous because it helps with minimizing the size of the incision on the eye (for example, minimum-invasive eye surgery), and helps patients recover faster post-surgery. 
     However, a fiber optic cable containing a laser fiber as well as an illumination fiber can only be made so narrow, because there must be room for both the illumination fiber and the laser fiber to be placed side-by-side in the tube. Also, narrowing of the two fibers themselves results in lower laser coupling efficiency and insufficient illumination to perform the medical procedure. Further, the fabrication of the probe integrating the two separate fibers (where one fiber is for the laser beam, and the other fiber is for the illumination light), is complicated, and the cost of manufacturing the probe is high. In addition, the thermal robustness of the probe is an issue at high laser power due to the plastic fiber used for illumination light, and the adhesive used to bind the fibers together at the distal end of the probe. 
     SUMMARY 
     According to one embodiment, a laser probe assembly is provided, including a probe body shaped and sized for grasping by a user, and a probe tip housing a fiber. The fiber includes a core, an outer cladding surrounding the core. The core is configured to transmit a laser light beam. The outer cladding is configured to transmit an illumination light. 
     According to another embodiment, a fiber is provided, including a core and an outer cladding surrounding the core. The core is configured to transmit a laser light beam. The outer cladding is configured to transmit the illumination light. 
     According to yet another embodiment, a surgical laser system is provided, including an illumination light source configured to emit an illumination light onto a focusing lens, a laser light source configured to emit a laser light beam onto the focusing lens, and the focusing lens. The focusing lens is configured to focus the illumination light onto a core and an outer cladding of a fiber coupled to the surgical laser system and focus the laser light beam onto the core of the fiber, wherein the fiber is downstream from the focusing lens. The fiber comprises the core configured to transmit the illumination light and the laser light beam and the outer cladding surrounding the core, wherein the outer cladding is configured to transmit the illumination light. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present technology, its features, and its advantages, reference is made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1A  illustrates a plan view of a system for generating laser light beams for delivery to a surgical target, in accordance with a particular embodiment of the present disclosure. 
         FIG. 1B  illustrates a plan view of a surgical laser system, in accordance with a particular embodiment of the present disclosure. 
         FIG. 2  illustrates a plan view of a probe, in accordance with a particular embodiment of the present disclosure. 
         FIGS. 3A-3B  illustrate a fiber, in accordance with a particular embodiment of the present disclosure 
         FIG. 4  illustrates a portion of a fiber, in accordance with a particular embodiment of the present disclosure. 
         FIG. 5  illustrates a portion of a fiber with an inner cladding, in accordance with a particular embodiment of the present disclosure. 
         FIG. 6  illustrates a partial cross-sectional view of a probe tip and a fiber, in accordance with a particular embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, details are set forth by way of example to facilitate an understanding of the disclosed subject matter. It should be apparent to a person of ordinary skill in the field, however, that the disclosed implementations are exemplary and not exhaustive of all possible implementations. Thus, it should be understood that reference to the described example is not intended to limit the scope of the disclosure. Any alterations and further modifications to the described devices, instruments, methods, and any further application of the principles of the present disclosure are fully contemplated as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one implementation may be combined with the features, components, and/or steps described with respect to other implementations of the present disclosure. 
     Embodiments of the disclosure generally relate to fibers and laser probe assemblies. A fiber includes a core that transmits a laser light beam, and the core and an outer cladding surrounding the core that transmits illumination light. A laser probe assembly includes a fiber, and the laser probe assembly allows the user to direct a laser light beam and illumination light in a single fiber. The combination of the transmission of laser light and illumination light in the same fiber results in a more compact fiber optic cable, allowing for medical procedures that require a narrower probe. Embodiments of the disclosure may be especially useful for, but are not limited to, a fiber that can transmit both laser light and illumination light. 
     As used herein, the term “about” may refer to a +/−10% variation from the nominal value. It is to be understood that such a variation can be included in any value provided herein. 
       FIG. 1A  illustrates a plan view of a system  100  for generating an illumination beam as well as a laser light beam for delivery to a surgical target, in accordance with a particular embodiment of the present disclosure. As shown, system  100  includes a surgical laser system  102  and a probe  108 . The system  100  produces an illumination beam  150  and a laser light beam  113  to be delivered to the retina  120  of a patient&#39;s eye  125 , in one example. 
     The surgical laser system  102  includes a number of laser light sources (e.g., one or more laser light sources) for generating laser light beams that can be used during an ophthalmic procedure. The surgical laser system  102  may be an ophthalmic surgical laser system configured to generate a laser light beam (e.g., a surgical treatment beam). A user, such as a surgeon or surgical staff member, can control the surgical laser system  102  (e.g., via a foot switch, voice commands, etc.) to fire the laser light beam to treat patient anatomy, e.g., perform photocoagulation. In some instances, the surgical laser system  102  includes a port, and the illumination beam and the laser light beam can be emitted through the port in the surgical laser system  102 . 
     System  100  can deliver the laser light beam  113  and the illumination light  150  from the port to a probe  108  via a fiber contained in the fiber optic cable  110 . As shown, probe  108  includes a probe body  112 , a probe tip  140 , and a distal end  145  of the probe tip. In operation, a laser light source of surgical laser system  102  generates the laser light beam  113 , while an illumination light source generates the illumination light  150 . The surgical laser system  102  multiplexes the laser light beam  113  and the illumination light  150  into a multiplexed beam  152 . The multiplexed beam  152  is directed to a lens of the surgical laser system  102  to focus the multiplexed beam onto an interface plane of a proximal end of the fiber within the fiber optic cable  110 , such that the multiplexed beam is transmitted along an entire length of the fiber. The interface plane of the proximal end of the fiber is exposed by a ferrule inserted into a port adapter  114  through which fiber optic cable  110  connects to the surgical laser system  102 . 
     The multiplexed beam  152  is transmitted by the fiber to the probe  108  disposed at the distal end of the fiber optic cable  110 . The multiplexed  152  beam exits the probe tip  145  and is projected onto the retina  120 . Thus, the surgical laser system  102  is configured to deliver the multiplexed beam  152  to the retina  120  through the fiber of the fiber optic cable  110 . The multiplexed beam  152  includes both the laser light beam  113  for the surgical procedure and illumination light  150  to aid the user in the procedure, although the beam associated with the laser light beam is narrower. 
     Note that, herein, a distal end of a component refers to the end that is closer to a patient&#39;s body, or where the laser light beam is emitted out of the laser probe  112 . On the other hand, the proximal end of the component refers to the end that is facing away from the patient&#39;s body or in proximity to, for example, the surgical laser source  102 . 
       FIG. 1B  illustrates a plan view of a surgical laser system  102 , in accordance with a particular embodiment of the present disclosure. As shown, the surgical laser system  102  includes a first lens  104  (e.g., collimating lens), a beam splitter  107 , a fiber optic cable  110 , a second lens  105  (e.g., focusing lens), an illumination light source  103 , and a laser light source  109 . The beam splitter  107  is downstream from the first lens  104 , the second lens  105  is downstream from the beam splitter  107 , and the fiber optic cable  110  is downstream from the second lens  105 . The illumination light source  103  emits an illumination light  150 . The illumination light  150  can be any spectrum of light, including, but not limited to, visible light or white light. The illumination light source  103  can be a light-emitting diode (LED) or a broadband laser source. The illumination light  150  is collimated by the first lens  104  such that the illumination light  150  is transformed into a beam of light with parallel rays, as shown. The first lens  104  can be any lens, including a plano-convex or biconvex lens. The beam splitter  107  allows the illumination light  150  to pass through the beam splitter  107  with a small fraction of the light reflected off the beam splitter. The illumination light  150  is then focused by the second lens  105 , as shown. The second lens  105  can be any lens used to focus light, including a plano-convex or biconvex lens. The illumination light  150  and laser beam  113  are focused and incident on the fiber optic cable  110  as a multiplexed beam  152 , which is described in greater detail below. 
     The second lens  105  focuses the multiplexed beam  152  into an interface plane of a proximal end of a fiber that is contained within the fiber optic cable  110 . As shown, fiber optic cable  110  is coupled to the surgical laser system  102  through port adapter  114 , which receives a ferrule  115  that exposes an interface plane of the proximal end of the fiber that is contained within fiber optic cable  110 . More specifically, the interface plane of the proximal end of the fiber is exposed through an opening  117  of ferrule  115 . The second lens  105  focuses multiplexed beam  152  onto an interface plane of the proximal end of the fiber such that the multiplexed beam is propagated through the fiber to the distal end of a surgical probe (e.g., probe  108  of  FIG. 1 ) that is coupled to cable  110 . 
     The fiber optic cable  110  may include a fiber (e.g., fiber  300 , a portion  311  of which is shown in  FIG. 4 ) having a core and an outer cladding, in some embodiments. In such embodiments, the second lens  105  is configured to focus the illumination light  150  onto both the core and the outer cladding, in which case both the outer cladding and the core transmit the illumination light  150 . 
     In yet some other embodiments, fiber optic cable  110  may include a fiber (e.g., the fiber whose portion  511  is shown in  FIG. 5 ) having a core, an inner cladding, and an outer cladding. In such embodiments, the illumination light  150  is focused on the core, the inner cladding, and the outer cladding in which case the core, the inner cladding, and outer cladding all transmit the illumination light  150 . 
     A laser light source  109  emits a laser light beam  113 . The laser light beam  113  can have any desired wavelength, such as from about 532 nm to about 635 nm. The laser light source  109  can emit a variety of wavelengths desired by the user. The laser light beam  113  is reflected by the beam splitter  107  onto focusing lens  105 . The laser light beam  113  is then focused by the second lens  105  onto an interface plane of the proximal end of fiber optic cable  110 , as part of the multiplexed beam  152 . The laser light beam  113  is transmitted by the core of the fiber optic cable  110 . The surgical laser system  102  provides both the illumination light  150  and the laser light beam  113  to the fiber optic cable  110  as the multiplexed beam  152 . Thus, a single fiber in the fiber optic cable  110 , including a core and an outer cladding, is capable of transmitting both the laser light beam  113  (through the core) and illumination light  150  (through the outer cladding and the core) in the same fiber. 
       FIG. 2  illustrates a plan view of the probe  108 , in accordance with a particular embodiment of the present disclosure. As described above, the probe  108  includes a probe body  112  shaped and sized for grasping by a user. Extending from the probe body  112  is the probe tip  140  with a distal end  145 . The fiber optic cable  110  typically comprises a fiber (e.g., fiber  300  of  FIG. 3 , the fiber of  FIG. 5 , etc.) surrounded by a polyvinyl chloride (PVC) tube for protecting the fiber during handling. The fiber extends through the probe body  112  and into the probe tip  140 . The multiplexed beam  152  emanates from the distal end of the fiber and, thereby, the distal end  145  of the probe tip  140  onto the retina. In some embodiments, the probe tip  140  comprises a first straight portion  250  and a second curved portion  251 . The first straight portion  250  includes a sleeve of the probe tip, and the second curved portion  251  includes a tube surrounding the fiber. The embodiment of  FIG. 2  is merely shown as an example. In other examples, a probe tip may be straight throughout, or the sleeve  250  is not included. A variety of other configurations are also possible and are not outside the scope of this disclosure, as one of ordinary skill in the art can appreciate. 
       FIGS. 3A-B  illustrate a fiber  300 , in accordance with a particular embodiment of the present disclosure. As shown, the fiber  300  includes a core  302 , an outer cladding  304 , a coating  306 , and a buffer  308 . The buffer  308  can include plastic, such as ethylene tetrafluoroethylene (ETFE). The buffer  308  is stripped at the proximal end of the fiber  300  so that a proximal end portion  311  (“portion  311 ”) of the fiber can be inserted to the ferrule. The buffer is also stripped at the distal end of the fiber  300  so that a distal end portion  312  (“portion  312 ”) of the fiber  300  can be inserted into probe tip  140 , according to some embodiments. 
       FIG. 4  illustrates a front view of the portion  311  of fiber  300 , in accordance with a particular embodiment of the present disclosure. The portion  311  includes a core  302  disposed in an outer cladding  304 , and the outer cladding  304  includes a material that can include fused silica. Note, however, that the portion  311  does not include the buffer  308 , as the buffer  308  has been stripped from around the portion  311 .  FIG. 4  can also illustrate a front view of the portion  312  of fiber  300 , which also does not include the buffer  308 . Laser light beam provided by a laser light source of the surgical laser system  102  is directed into the core  302  of the fiber  300 . Thus, the core  302  conducts the laser light beam along the length of the fiber  300 . Both core  302  and outer cladding  304  may include fused silica. However, the core  302  is doped with a dopant that increases the index of refraction of the core  302 . Therefore, the refractive index of the core  302  is greater than the refractive index of the outer cladding  304 , such that the laser light beam traveling along the core  302  is contained within the core and prevented from escaping from the core  302  into the outer cladding  304 . In one example, the dopant can include germanium (Ge). The core  302  and the outer cladding  304  transmit illumination light from the surgical laser system  102 . Thus, a single fiber including the core  302  and the outer cladding  304  is capable of transmitting both the laser light beam (through the core  302 ) and illumination light (through the outer cladding  304  and the core  302 ). In addition, using fused silica for transmitting the illumination light, such as in fiber  300  of  FIG. 3  or the fiber of  FIG. 5 , results in a more thermally stable fiber as compared to a conventional illumination fiber that is made of traditional plastic, and there is no need to use adhesive to bond two fibers, which makes the fiber more thermally robust. 
     A coating  306  is formed over the outer cladding  304 . In some instances, the coating  306  is a hard polymer coating. In other instances, the coating  306  is formed from other materials, such as acrylate. The refractive index of the coating  306  is less than the refractive index of the outer cladding  304 , such that the illumination light traveling along the outer cladding  304  is contained within the outer cladding  304  and prevented from escaping from the outer cladding  304  into the coating  306 . In certain embodiments, the numerical aperture (NA) between the outer cladding  304  and the coating  306  is greater than about 0.5 to provide the wide illumination required in some surgical cases. 
       FIG. 5  illustrates a portion  511  of a fiber with an inner cladding  503 , in accordance with a particular embodiment of the present disclosure. Portion  511  corresponds to a proximal or a distal portion of a fiber, where the fiber&#39;s buffer has been stripped. In the fiber of  FIG. 5 , the inner cladding  503  surrounds a core  502  and the outer cladding  304  surrounds the inner cladding  503 . The inner cladding  503  can include fused silica doped with dopants, the dopants including fluorine, chlorine, boron, or any combination of the above, according to some embodiments. The dopants change the optical properties of the inner cladding  503 , for example, the refractive index. In certain embodiments, the NA between the core  502  and the inner cladding  503  is from about 0.20 to about 0.30, such as about 0.22. The inner cladding  503  keeps the laser light beam from entering the outer cladding  304  by causing partial or total internal reflection of the laser light beam, thus keeping the laser light beam in the core. As described above, in the example of  FIG. 5 , the illumination light is focused by the surgical laser system onto core  502 , inner cladding  503  and outer cladding  304  while the laser light beam is focused on core  502 . 
     Referring to  FIGS. 4 and 5 , in certain embodiments, the diameter of the core  302 ,  502  is from about 70 μm to about 80 μm, the outer diameter of the outer cladding  304  is from about 290 μm to about 300 μm, and the outer diameter of the coating  306  is from about 320 μm to about 330 μm. The location of the center  302   c ,  502   c  of the core  302 ,  502  is approximately the same location as the center  304   c  of the outer cladding  304 , according to one embodiment. Other diameters are also contemplated. 
       FIG. 6  illustrates a partial cross-sectional view of a probe tip  140 , in accordance with a particular embodiment of the present disclosure. The portion  511  is surrounded by the tube  602 , and the tube is surrounded by the sleeve  624  of the probe tip  140 . The tube  602  can include any suitable material, e.g., Nitinol, nickel titanium, or stainless steel. The sleeve  624  can include, for example, stainless steel. In the example of  FIG. 6 , the distal end of the portion  511  and the distal end of the tube  602  surrounding the fiber extend beyond the distal end of the sleeve  624  of the probe tip  140 . Thus, the first straight portion  250  of the probe tip  140  includes the sleeve  624 , whereas the second curved portion  251  of the probe tip does not include the sleeve, although the portion  511  is still surrounded by the tube  604  in the second curved portion. In other embodiments, the sleeve  624  extends to cover the entire portion  511  throughout the probe tip  140 . In other embodiments, the probe tip  140  includes the tube  602  and the sleeve  624  is not included. Although the portion  511  illustrated in  FIG. 6  includes the inner cladding  503 , the fiber optic cable could instead include the portion  311  (which does not include the inner cladding), without any loss of generality. As described above, the embodiment of  FIG. 6  is merely shown as an example. One of ordinary skill in the art can appreciate other embodiments with different configurations (e.g., a completely straight probe tip, or a probe tip with a distal end that is flush with the distal ends of the fiber of  FIG. 5  and tube  602 ) which are also not outside the scope of this disclosure. 
     As described above, a fiber optic cable is capable of transmitting both a laser light beam through a core, and illumination light through the core and an outer cladding. The fiber optic cable does not have two separate fibers for illumination light and the laser light beam, but rather one fiber that includes a core to transmit the laser light beam, and the core and an outer cladding to transmit the illumination light. The fiber optic cable can be used in a system for medical procedures, and the system provides both laser light beam for the cauterizing or burning, and illumination light to aid the user in performance of the procedure. 
     The use of a combined core and outer cladding to transmit both the laser light beam and illumination light results in a more compact fiber, and removes the need for adhering two fibers together. The narrower fiber is useful for medical procedures that require thinner probe tips. In addition, the fiber optic cable is more thermally stable than a traditional fiber optic cable, due to the lack of thermally unstable adhesive. The use of a single fiber in the fiber optic cable removes the need for two connectors (one for each fiber), and thus only one connector is necessary, which reduces the manufacturing and labor costs, as there is no need to handle assembly of two fibers 
     The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.