Endoscope comprising an optical fiber for delivering illumination light

Abstract

The summary of the invention provides an endoscope including an optical fiber that delivers illumination light. The endoscope can include an elongated endoscope body. The optical fiber can extend along the endoscope body. The optical fiber can direct treatment light and illumination light longitudinally along the optical fiber to a distal end portion of the endoscope body. The treatment light and the illumination light can have different wavelengths. A wavelength sensitive light splitter disposed at the distal end portion of the optical fiber can direct the illumination light laterally out of the optical fiber through a lateral face of the optical fiber at the distal end portion of the optical fiber and allow the treatment light to longitudinally exit the optical fiber through a distal end of the optical fiber. Examples of suitable wavelength sensitive light splitters can include one or more fiber Bragg gratings that can be angled or a diffraction grating disposed on a lateral edge of a length of a coreless optical fiber.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 262,853, filed October 21, 2021, and U.S. Provisional Patent Application No. 63 / 362,930, filed April 13, 2022, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to endoscopy. Background Technology

[0004] An endoscope is a light-transmitting device that illuminates a target and provides an image of that illuminated target. The size, shape, and function of an endoscope can be customized to examine a patient's specific organs for a variety of medical procedures. For example, a nephroscope is an endoscope designed to illuminate and view kidney stones or other objects within the kidney region. Similarly, a cystoscope is an endoscope that illuminates and views portions of the bladder. Other types of endoscopes, including laparoscopes, can be used to examine other organs.

[0005] We are currently working to improve the endoscope. Summary of the Invention

[0006] In the example, the endoscope may include: an elongated endoscope body; an optical fiber extending along the endoscope body, the optical fiber being configured to guide a treatment light and an illumination light longitudinally along the optical fiber to a distal portion of the endoscope body, the treatment light and the illumination light having different wavelengths; and a wavelength-sensitive light splitter disposed at the distal portion of the optical fiber, the wavelength-sensitive light splitter being configured to guide the illumination light to exit the optical fiber laterally through the side of the optical fiber at the distal portion of the optical fiber, and to allow the treatment light to exit the optical fiber longitudinally through the distal end of the optical fiber.

[0007] In the example, a method for delivering light in an endoscope may include: guiding a treatment light and an illumination light longitudinally along an optical fiber to a distal portion of an elongated endoscope body, the treatment light and the illumination light having different wavelengths; using a wavelength-sensitive light splitter to guide the illumination light to exit the optical fiber laterally through the side of the optical fiber at the distal portion of the optical fiber; and using a wavelength-sensitive light splitter to allow the treatment light to exit the optical fiber longitudinally through the distal end of the optical fiber.

[0008] In the example, the endoscope may include: an elongated endoscope body; an optical fiber extending along the endoscope body, the optical fiber being configured to guide infrared therapeutic light and visible illumination light longitudinally along the optical fiber to a distal portion of the endoscope body; and an angled fiber Bragg grating disposed along the length of the distal portion of the optical fiber, the angled fiber Bragg grating being configured to reflect at least some of the visible illumination light out of the optical fiber through the side of the optical fiber, and to transmit infrared therapeutic light through the angled fiber Bragg grating to exit the optical fiber longitudinally through the distal end of the optical fiber. Attached Figure Description

[0009] Figure 1 A stereoscopic view of an example endoscope is shown.

[0010] Figure 2 It shows Figure 1 A cross-sectional side view of an example of the distal portion of the optical fiber of an endoscope.

[0011] Figure 3 It shows Figure 2 The end face cross-section of the optical fiber is taken orthogonally to the longitudinal axis of the fiber in the region where the inner and outer sheaths are absent.

[0012] Figure 4 It shows Figure 2 A cross-sectional view of the distal portion of an optical fiber, the cross-section being taken orthogonally to the longitudinal axis of a first example of an optical fiber distal portion having a structure different from that of the proximal portion of the optical fiber.

[0013] Figure 5 An end-face cross-sectional view of an example of the distal portion of an optical fiber is shown. This cross-section is taken orthogonally to the longitudinal axis of the optical fiber for a first example of the distal portion of an optical fiber having a structure different from that of the proximal end of the distal portion.

[0014] Figure 6 An example end-face cross-sectional view of the far end portion of the optical fiber is shown.

[0015] Figure 7 An example end-face cross-sectional view of the far end portion of the optical fiber is shown.

[0016] Figure 8 An example end-face cross-sectional view of an optical fiber comprising multiple cores is shown.

[0017] Figure 9 It shows Figure 8 An example end-face cross-sectional view of the distal portion of an optical fiber.

[0018] Figure 10 An example end-face cross-sectional view of an optical fiber comprising multiple cores is shown.

[0019] Figure 11 It shows the use of Figure 10 An example end-face cross-sectional view of the distal portion of an optical fiber.

[0020] Figure 12 An example end-face cross-sectional view of the far end portion of the optical fiber is shown.

[0021] Figure 13 It is applicable to Figure 1 A cross-sectional side view of an example of the distal portion of the optical fiber used in an endoscope.

[0022] Figure 14 It shows Figure 13 The end view of the far end of the optical fiber.

[0023] Figure 15 An example of a method for delivering light in an endoscope is shown.

[0024] Throughout the various views, corresponding reference numerals indicate the corresponding components. Elements in the accompanying drawings are not necessarily drawn to scale. The configurations shown in the drawings are merely illustrative and should not be construed as limiting in any way. Detailed Implementation

[0025] The endoscope may include an optical fiber that can guide therapeutic and illumination light longitudinally along the fiber to a distal portion of the endoscope. The therapeutic and illumination light can have different wavelengths. For example, the illumination light wavelength may fall within the visible portion of the electromagnetic spectrum, while the therapeutic light wavelength is not limited to this. At the distal portion of the optical fiber, the fiber can guide the therapeutic light to exit the fiber longitudinally through the distal end, and guide the illumination light to exit the fiber circumferentially through the side of the fiber at the distal portion.

[0026] In some examples, the therapeutic and illumination beams can be combined and propagated along the fiber to the distal portion of the fiber. In these examples, a wavelength-sensitive light splitter, such as a diffraction grating, can separate the illumination beam from the therapeutic beam. Figures 2 to 7 An example of an optical fiber configuration is shown, in which therapeutic light and illumination light can propagate along the optical fiber in combination. Figure 13 and Figure 14 Another example of an optical fiber configuration is shown, in which therapeutic light and illumination light can propagate along the optical fiber in combination.

[0027] In some examples, the optical fiber may include multiple cores that can keep the therapeutic and illumination light separated as they propagate along the fiber. In these examples, the optical fiber may allow light from only one of the cores to exit the fiber through the side of the fiber, for example, by thinning the fiber near one of the cores. Figures 8 to 11An example of an optical fiber configuration is shown, in which therapeutic and illumination light can propagate separately along individual cores within the optical fiber. In some examples, an optical fiber bundle can be used, which can propagate therapeutic and illumination light from different fibers within the bundle to a distal portion of the bundle.

[0028] Compared to endoscopes that include an illumination source such as a light-emitting diode at their distal end, the endoscope described in detail below may lack a light-emitting diode and its associated circuitry. As a result, compared to comparable endoscopes that include an illumination source at their distal end, the endoscope described in detail below can have reduced complexity (and therefore lower cost) and can generate less heat at its distal end.

[0029] Figure 1 A perspective view of an example of endoscope 100 is shown. Figure 1 The configuration shown is just one example of an endoscope; other configurations can also be used.

[0030] As used herein, the term endoscope includes a class of devices capable of illuminating an organ or target within a patient, capturing an image of the illuminated organ or target, and optionally delivering treatment to the organ or target. Endoscopes whose shape and size are suited to a particular organ or procedure may be referred to by more specific names. For example, a cystoscope is shaped and sized to treat a patient's bladder, a nephroscope is shaped and sized to treat a patient's kidney, a bronchoscope is shaped and sized to treat a patient's bronchi, an arthroscope is shaped and sized to treat a specific joint, a colonoscope is shaped and sized to treat a patient's colon, a laparoscope is shaped and sized to treat a patient's abdomen or pelvis, and so on. Each of these specific names may refer to a particular type of endoscope. For simplicity, endoscope 100 is described below as being configured to treat kidney stones; it should be understood that treating kidney stones is merely one example of the use of endoscope 100, and other uses are possible.

[0031] Endoscope 100 may include an elongated endoscope body 102, which is at least partially insertable into a patient. Endoscope body 102 may include a graspable proximal portion 104. Endoscope body 102 may include an elongated portion 106 extending from the graspable proximal portion 104. The elongated portion 106 may be entirely rigid or may have one or more flexible portions. The elongated portion 106 may extend to a distal endoscope body portion 108. Endoscope body 102 may include a joint controller 110 located on the graspable proximal portion 104 of endoscope body 102. When endoscope body 102 is inserted into a patient's kidney, joint controller 110 may adjust the position of the distal endoscope body portion 108 to locate a target such as a kidney stone. Endoscope body 102 may include a camera 112 located distal to the distal endoscope body portion 108. The endoscope body 102 may include an electrical connection 114 for power supply and data signals representing captured video images. The electrical connection 114 extends from a grippable proximal portion 104 along an elongated portion 106 to a distal endoscope body portion 108. A camera 112 may capture video images of the target and / or illuminated tissue surrounding the target. During the procedure, the distal endoscope body portion 108 may illuminate the target, provide video images of the illuminated target, ablate the target, and optionally, remove all or part of the ablated target.

[0032] To ablate a target, the distal endoscope body 108 can deliver therapeutic light 116 to the target or to fluid near the target. The target or fluid near the target can absorb all or part of the therapeutic light 116 and evaporate in response. The evaporated fluid can mechanically impact the kidney stone. Repeated emission, absorption, and mechanical impaction of the kidney stone in this manner can break it into smaller fragments. The physician can remove the smaller kidney stone fragments through the endoscope body 102. The physician can use the illumination and imaging features of the endoscope 100 to determine that all kidney stone fragments have been removed from the patient. The physician can then remove the endoscope body 102 from the patient.

[0033] Endoscope 100 may include an optical fiber 118 extending along endoscope body 102. Optical fiber 118 may guide a treatment light 116 and an illumination light 120 longitudinally along optical fiber 118 to a distal endoscope body portion 108. The proximal end of optical fiber 118 may be removably coupled to one or more light sources, such as a pulsed laser for the treatment light 116 and one or more light-emitting diodes for the illumination light 120. The treatment light 116 from the pulsed laser may propagate longitudinally along optical fiber 118 from the proximal portion 104 to the distal endoscope body portion 108 of endoscope body 102 and may exit from the distal end of optical fiber 118 to perform treatment. By using optical fiber 118 to deliver the treatment light 116 (instead of including the treatment light source in endoscope body 102), endoscope 100 can be used with any suitable light source and / or can be switched from a first light source to a second light source during surgery without removing endoscope body 102 from the patient.

[0034] The therapeutic light 116 and the illumination light 120 can have different wavelengths.

[0035] The therapeutic beam 116 can be absorbed by a target or by a fluid surrounding the target. Because the therapeutic beam 116 is designed to be absorbed by a fluid such as water, it can have a spectrum including one or more wavelengths where water has a relatively high absorption rate. Water can have relatively high absorption for a specific wavelength (e.g., a peak) or a wavelength region (e.g., a relatively broad spectral region) in the infrared portion of the electromagnetic spectrum. In some examples, the therapeutic beam 116 can have wavelengths in the infrared portion of the electromagnetic spectrum. In some examples, the therapeutic beam 116 can have a wavelength corresponding to the emission wavelength of a pulsed thulium laser. In some examples, the therapeutic beam 116 can have a wavelength between 1810 nm and 2100 nm. In some examples, the therapeutic beam 116 can have a wavelength of approximately 1940 nm. Other wavelengths or wavelength regions can also be used. In some examples, the therapeutic beam 116 can be generated by an infrared laser, such as a pulsed thulium laser, and coupled to the proximal end of an optical fiber 118.

[0036] Illumination light 120 can illuminate an area or volume near the distal end of optical fiber 118. Because illumination light 120 is designed to visually illuminate a portion of a target or tissue, it can have a spectrum that includes all or a portion of the visible portion of the electromagnetic spectrum. In some examples, illumination light 120 can have at least one wavelength between 400 nm and 700 nm. In some examples, illumination light 120 can include a wavelength continuum, at least a portion of which is between 400 nm and 700 nm. In some examples, illumination light 120 can be white light, having a spectrum that is perceived as white or near-white when observed by the human eye. In some examples, illumination light 120 can be generated by a white light-emitting diode and coupled to the proximal end of optical fiber 118.

[0037] Figure 2 It shows the use of Figure 1 A cross-sectional side view of an example of the distal portion of the optical fiber 118 of the endoscope 100.

[0038] The optical fiber 118 may include a core 202, which is elongated and extends along the length of the optical fiber 118. The core 202 may be formed of a core material 204 having a core refractive index. The core material 204 may be relatively transparent (e.g., having relatively low absorption) in the wavelength range of the therapeutic light 116 and the illumination light 120.

[0039] The optical fiber 118 may include a cladding 206 surrounding the core 202 along the length of the optical fiber 118. The cladding 206 may be formed of a cladding material 208 having a cladding refractive index lower than that of the core. The cladding material 208 may be relatively transparent (e.g., having relatively low absorption) in the wavelength range of the therapeutic light 116 and the illumination light 120.

[0040] For simplicity, the optical fiber 118 described herein is referred to as a step-index optical fiber 118, which includes a discrete (and smooth) boundary between a core 202 (having a core refractive index) and a cladding 206 (having a cladding refractive index less than the core refractive index). Alternatively, a graded-index optical fiber 118 may be used, wherein the refractive index may vary continuously with distance from the longitudinal axis 210 of the optical fiber 118. Both step-index and graded-index optical fibers 118 may be used in the endoscope 100.

[0041] In some examples, fiber 118 may be multimode fiber 118. In multimode fiber 118, when the guide light is reflected and propagates from cladding 206 via total internal reflection at the boundary between core 202 and cladding 206, most of the guide light remains in core 202. The boundary between core 202 and cladding 206 can be relatively smooth, allowing total internal reflection to be supported at every location on the boundary. For example, guide light 216 in core 202 can illuminate cladding 206 and be reflected from cladding 206 via total internal reflection as reflected guide light 218. Similarly, guide light 220 in core 202 can illuminate cladding 206 and be reflected from cladding 206 via total internal reflection as reflected guide light 222. In multimode fiber 118, core 202 can be relatively large compared to the wavelength of the guide light, for example, 50 times, 100 times, 200 times, or greater than 200 times the wavelength. The core diameter of some multimode optical fibers 118 may include 50 micrometers, 62.5 micrometers, 100 micrometers, and 200 micrometers, but other suitable values ​​may also be used. The cladding diameter of some multimode optical fibers 118 may include 80 micrometers and 125 micrometers, but other suitable values ​​may also be used.

[0042] In some examples, fiber 118 may be single-mode fiber 118. In single-mode fiber 118, the guiding light can have a generally invariant modal shape as light propagates along the fiber (rather than individual rays propagating through continuous reflections from the boundary between core 202 and cladding 206). In single-mode fiber 118, the guiding light can include a significant amount of optical power in both core 202 and cladding 206. In single-mode fiber 118, core 202 can be slightly larger than the wavelength of the guiding light, for example, 10 times, 5 times, or less than 5 times the wavelength. The core diameter of some single-mode fiber 118 may be between 8 and 10 micrometers, but other suitable values ​​may also be used. The cladding diameter of some multimode fiber 118 may include 80 and 125 micrometers, but other suitable values ​​may also be used.

[0043] Optical fiber 118 may include additional non-optical elements that are structural in nature and may not transmit light (e.g., may be opaque). An inner sheath 212 may surround cladding 206. An outer sheath 214 may surround the inner sheath 212. The diameter of the outer sheath 214 for a particular single-mode optical fiber 118 may include 900 micrometers, but other suitable values ​​may also be used. The inner sheath 212 and the outer sheath diameter 214 may stop before the distal portion of optical fiber 118, such that the outer surface of the distal portion is exposed and not covered by the inner sheath 212 and the outer sheath 214.

[0044] Figure 3 It shows Figure 2The diagram shows an end-view cross-section of optical fiber 118, taken perpendicular to the longitudinal axis 210 of fiber 118 in the region lacking the inner sheath 212 and outer sheath 214. The cross-section illustrates a core 202 formed of core material 204, surrounded by a cladding 206 formed of cladding material 208. In some examples, both core 202 and cladding 206 may be rotationally symmetric about the longitudinal axis 210 of optical fiber 118. In some examples, both core 202 and cladding 206 may have a circularly symmetric cross-section. Other symmetric and asymmetric configurations may also be used.

[0045] Return to Figure 2 The optical fiber 118 may include a distal portion 224, which may have a different structure from the proximal portion of the optical fiber 118.

[0046] As a first example of an optical fiber distal portion 224 having a structure different from that of the optical fiber 118 at the near end of the optical fiber distal portion 224, the optical fiber distal portion 224 may lack the core / cladding structure that guides light in the optical fiber 118. In some examples, the optical fiber distal portion 224 may have a substantially uniform refractive index. For example, the optical fiber distal portion 224 may be formed as a coreless fiber (e.g., only cladding, no core) that is spliced, fused, or otherwise attached to the distal end of the optical fiber 118. The optical fiber distal portion 224 may be formed of material 226, which is the core material 204, the cladding material 208, or other suitable material with a refractive index relatively close to that of the core material or the cladding material (e.g., within the values ​​of 0.2, 0.1, 0.05, or other suitable values).

[0047] The therapeutic light 116 and the illumination light 120 can propagate longitudinally along the optical fiber 118 as guide lights. The distal portion 224 of the optical fiber can receive the guided light and propagate it distally within the distal portion 224 as an unguided light. As the unguided light propagates distally within the distal portion 224, it can extend radially to illuminate the sides (e.g., the outer circumferential surface) of the distal portion 224. For example, the unguided light 228 can illuminate the wavelength-sensitive light splitter 230 (described in detail below), where some or all of the therapeutic light is reflected to form reflected light 232, and some or all of the illumination light is transmitted to form transmitted light 234. Similarly, the unguided light 236 illuminates the wavelength-sensitive light splitter 230, where some or all of the therapeutic light is reflected to form reflected light 238, and some or all of the illumination light is transmitted to form transmitted light 240. Transmitted light 234 and 240 can form illumination light 120 (…). Figure 1 Reflected rays 232 and 238 can be transmitted through the distal end 242 of optical fiber 118 to form therapeutic light 116. Figure 1 ).

[0048] Figure 4 It shows Figure 2 The cross-sectional view of the end face of the fiber distal portion 224 is shown. This cross-section is taken perpendicular to the longitudinal axis 210 of the fiber 118 for a first example of the fiber distal portion 224 having a structure different from that of the fiber 118 at the proximal end of the fiber distal portion 224. Figure 4 The view shows material 226 lacking a core / cladding structure (e.g., having a uniform refractive index) and at least partially surrounded by a wavelength-sensitive light splitter 230 (described in detail below).

[0049] Other configurations for the fiber optic remote section 224 are possible. For clarity, similar to... Figure 4 The views shown are in cross-section of these other configurations. It is understood that any or all of the fiber optic remote portion configurations described herein can be used with any or all of the fiber optic configurations described herein. For the purposes of the following discussion, fiber optic remote portion 224 is considered part of fiber optic 118, such that the distal end 242 of fiber optic 118 includes fiber optic remote portion 224.

[0050] Figure 5 An end-face cross-sectional view of an example of the fiber distal portion 224' is shown. This cross-section is taken perpendicular to the longitudinal axis 210 of the fiber 118 for a second example of the fiber distal portion 224' having a structure different from that of the fiber proximal to the fiber distal portion 224'.

[0051] In a second example of a fiber distal portion 224' having a different structure than that of the fiber proximal to the distal portion 224', the cladding 206' may have a reduced thickness in the fiber distal portion 224'. This reduced cladding thickness allows therapeutic and illumination light to illuminate the circumferential outer surface of the fiber distal portion 224', optionally retaining the same core 202' used throughout the entire length of the fiber. In some examples, the cladding 206' may have a first thickness near the midpoint between the fiber distal portion 224' and the fiber proximal to the fiber, and a second thickness at the fiber distal portion 224', wherein the second thickness may be less than the first thickness. A wavelength-sensitive optical splitter 230 (described in detail below) may at least partially surround the cladding 206'.

[0052] The distal portion 224 of optical fiber 118 may include a wavelength-sensitive optical splitter 230. Figure 2 , Figure 4 and Figure 5Wavelength-sensitive optical splitter 230 can be disposed on the lateral surface or side of the distal portion 224 (or 224') of optical fiber 118. Wavelength-sensitive optical splitter 230 can guide therapeutic light 116 to exit longitudinally through the distal end of optical fiber 118. Figure 1 and Figure 2 Wavelength-sensitive optical splitter 230 can guide illumination light 120 to circumferentially exit optical fiber 118 through the side of the distal portion 224 of optical fiber 118. Figure 1 and Figure 2 ).

[0053] Figure 6 A cross-sectional view of an example distal portion 600 of an optical fiber is shown. In some examples, a wavelength-sensitive light splitter may include a dichroic thin-film coating 602 disposed on the side of the optical fiber at the distal portion 600. The dichroic thin-film coating 602 may reflect at least some of the therapeutic light and transmit at least some of the illumination light. In some examples, the distal portion 600 may be formed of a material 604 having a constant refractive index over a cross-sectional region of the optical fiber, the cross-section being orthogonal to the longitudinal axis of the optical fiber. In some examples, the distal portion 600 may have a uniform refractive index. When therapeutic and illumination light emitted from the core propagate distally in the distal portion 600 to irradiate the dichroic thin-film coating 602, the therapeutic and illumination light may extend radially in a conical manner.

[0054] In some of these examples where the dichroic thin-film coating 602 can reflect at least some of the therapeutic light and transmit at least some of the illumination light, the wavelength-sensitive light splitter may further include a light redirector 606 that can redirect the transmitted illumination light. Without such a light redirector 606, the illumination light that has been transmitted through the dichroic thin-film coating 602 can remain within the fiber distal portion 600 because the illumination light can strike the outside of the fiber distal portion 600 at an angle of incidence greater than the critical angle, thus undergoing total internal reflection, which can retain the illumination light within the fiber distal portion 600. The light redirector 606 can violate the condition of total internal reflection, thus coupling some or all of the illumination light out of the fiber distal portion 600.

[0055] The dichroic thin film coating 602 may be disposed between the central (e.g., internal) portion of the fiber optic distal portion 600 and the optical redirector 606. To space the dichroic thin film coating 602 from the optical redirector 606, the fiber optic distal portion 600 may include an optional spacer layer.

[0056] Figure 7 A cross-sectional view of an example end face of the distal portion 700 of the optical fiber is shown. Figure 7In this configuration, the dichroic thin film coating 602 can be disposed on the circumferential edge of the far end portion 700 of the optical fiber, the spacer layer 704 can be disposed on the dichroic thin film coating 602, and the optical redirector 606 can be disposed on the spacer layer 704. Other suitable configurations can also be used.

[0057] In some examples, the light redirector 606 may include a light scatterer such as a textured or roughened surface. A textured surface can scatter illumination light by giving light irradiating the textured surface a random propagation direction. This random propagation direction can violate the condition of total internal reflection, allowing the textured surface to couple some or all of the illumination light out of the distal fiber portion 600 or 700. Note that the dichroic thin-film coating 602 can prevent all or most of the therapeutic light from irradiating the textured surface, such that the textured surface couples the illumination light out only or primarily from the distal fiber portion 600 or 700.

[0058] In some examples, the optical redirector 606 may include a diffraction grating. The diffraction grating may couple at least some of the illumination light to a diffraction order (e.g., a negative first diffraction order) to couple some or all of the illumination light out of the fiber distal portion 600 or fiber distal portion 700. The diffraction grating may include diffraction features (e.g., grating lines) substantially orthogonal to the longitudinal axis of the fiber. In some examples, the diffraction features may have a feature depth selected to improve the diffraction efficiency of the negative first order (or negative second order, or other suitable non-zero order) of the illumination light. The diffraction features or grating lines may be spaced apart by a grating spacing (e.g., uniformly spaced). The grating spacing may be selected such that illumination light incident on the diffraction grating at an incident angle greater than the critical angle can be coupled to a negative first (or other suitable) diffraction order. For example, the grating spacing may be selected such that the diffraction order can propagate in free space away from the fiber distal portion at an appropriate angle (e.g., an angle allowing the illumination light to travel toward the target as it propagates away from the longitudinal axis of the fiber). This suitable grating spacing can be calculated from the well-known grating equations. Note that the dichroic thin film coating 602 can prevent all or most of the therapeutic light from illuminating the diffraction grating, so that the diffraction grating couples out only or primarily the illumination light from the distal portion 600 or the distal portion 700 of the optical fiber.

[0059] In some examples, the functions of a wavelength-sensitive optical splitter and an optical redirector can be combined into a single diffraction grating. Such a bifunctional diffraction grating can be positioned on the side of the fiber at the distal end. Unlike the configuration described above, the bifunctional diffraction grating can receive both illumination light (the visible portion of the electromagnetic spectrum) and therapeutic light (the infrared portion of the electromagnetic spectrum). The diffraction grating can reflect at least some of the therapeutic light and transmit at least some of the illumination light. This bifunctional diffraction grating can have diffraction features spaced apart by a characteristic interval. The characteristic interval can be selected such that at least some of the illumination light is transmitted through the diffraction grating at a negative first order, and the therapeutic light does not produce any diffraction order. Such a characteristic interval can be determined by applying the grating equation twice, once for the wavelength of the illumination light and once for the wavelength of the therapeutic light. In some examples, the diffraction features can be arranged orthogonally to the longitudinal axis of the fiber. In some examples, the diffraction features can have a characteristic depth, which is selected to improve the negative first-order diffraction efficiency of the illumination light.

[0060] In the detailed description above Figures 2 to 7 In this configuration, the optical fiber may include a single core. The therapeutic light and illumination light can propagate together along this single core to the distal portion of the fiber. At the distal portion, a wavelength-sensitive optical splitter can separate the therapeutic light and illumination light.

[0061] The following is a detailed description Figures 8 to 11 In this configuration, the optical fiber may include multiple cores. Therapeutic and illumination light can propagate along different cores of the fiber to the distal portion of the fiber. At the distal portion, the fiber can be configured to guide the illumination light (from the core guiding the illumination light) circumferentially away from the fiber through its sides. For example, the cladding may be thinned and / or textured near the core of the illumination light to allow the illumination light to exit the fiber circumferentially through its sides. Near the core guiding the therapeutic light, the cladding may remain unchanged in thickness and / or texture, allowing the therapeutic light to exit the fiber longitudinally through its distal end.

[0062] The endoscope may include optical fibers that can guide therapeutic and illumination light longitudinally to the distal portion of the endoscope. The therapeutic and illumination light may have different wavelengths.

[0063] Figure 8A cross-sectional view of an example optical fiber 800 including multiple cores 802, 804 is shown. The optical fiber 800 may include a first core 802 that can guide therapeutic light to a distal portion of an endoscope. The optical fiber 800 can guide the therapeutic light to exit longitudinally through its distal end. The optical fiber 800 may include a second core 804 that can guide illumination light to a distal portion of the endoscope. The optical fiber 800 can guide the illumination light to exit circumferentially through its lateral side at the distal portion of the optical fiber 800.

[0064] In some examples, the first core 802 and the second core 804 may extend generally along the longitudinal direction of the optical fiber 800. For example, both the first core 802 and the second core 804 may be generally parallel to the longitudinal axis of the optical fiber 800. As another example, both the first core 802 and the second core 804 may advance helically about the longitudinal axis of the optical fiber 800.

[0065] In some examples, the first core 802 and the second core 804 may be formed of a material having a first refractive index. The optical fiber 800 may include a cladding 806 surrounding the first core 802 and the second core 804. The cladding 806 may be formed of a cladding material having a second refractive index less than the first refractive index. The dimensions of the cladding 806 may isolate the therapeutic light from the second core and the illumination light from the first core. For example, the first core 802 may define a first propagation mode with a first mode size, the second core 804 may define a second propagation mode with a second mode size, and the cladding 806 may separate the first core 802 and the second core 804 by a distance greater than the sum of the first mode size and the second mode size.

[0066] In the far end portion of the optical fiber 800, the cladding 806 may be thinned near the second core 804 to extract light from the second core 804 instead of the first core 802. Figure 9 It shows Figure 8 An example end-face cross-sectional view of the distal portion 900 of an optical fiber 800.

[0067] The cladding 806 may be thinned in a region near the second core 804 to allow light in the second core 804 to be directed to the optical redirector 606. As a specific example, near the midpoint between the distal and proximal portions of the optical fiber 800, the second core 804 may be spaced apart from the outer edge of the cladding 806 by a first spacing. At the distal portion of the optical fiber 800, the second core 804 may be spaced apart from the outer edge of the cladding 806 by a second spacing smaller than the first spacing. In some of these examples, the second spacing may be selected such that the propagation pattern of the illumination light extends to the outer edge of the cladding 806 at the distal portion of the optical fiber 800. At least some of the illumination light may exit the optical fiber 800 at the distal portion of the optical fiber 800.

[0068] To guide illumination light out of fiber optic 800, the fiber optic cable may include an optical redirector 606 (e.g., a textured surface). The optical redirector 606 may violate the condition of total internal reflection, thus coupling some or all of the illumination light out of the distal portion of fiber optic 800. The optical redirector 606 has been described in detail above.

[0069] Figure 10 A cross-sectional view of an example optical fiber 1000 including multiple cores 1002, 1004 is shown. The optical fiber 1000 may include a first core 1002 that can guide therapeutic light to a distal portion of an endoscope. The optical fiber 1000 can guide the therapeutic light to exit longitudinally through its distal end. The optical fiber 1000 may include a second core 1004 that can guide illumination light to a distal portion of the endoscope. The optical fiber 1000 can guide the illumination light to exit circumferentially through its lateral side at the distal portion of its distal end.

[0070] exist Figure 10 In this configuration, a first core 1002 may extend along the longitudinal axis of the optical fiber 1000. A second core 1004 may extend cylindrically around the first core 1002. The first core 1002 and the second core 1004 may be formed of a material having a first refractive index. The optical fiber 1000 may include an inner cladding 1006 disposed between the first core 1002 and the second core 1004. The inner cladding 1006 may be formed of a cladding material having a second refractive index, which is less than the first refractive index. The dimensions of the inner cladding 1006 may isolate the therapeutic light from the second core 1004 and isolate the illumination light from the first core 1002. The optical fiber 1000 may include an outer cladding 1008 surrounding the second core 1004. The outer cladding 1008 may be formed of a cladding material.

[0071] In the far end portion of the optical fiber 1000, the outer cladding 1008 may be thinned to extract light from the second core 1004 instead of the first core 1002. Figure 11 It shows Figure 10 An example end-face cross-sectional view of the distal portion 1100 of optical fiber 1000.

[0072] The outer cladding 1008 may be thinned in a region near the second core 1004 to allow light in the second core 1004 to be directed to a light redirector 606, such as a textured surface. As a specific example, the outer cladding 1008 may have a first thickness near the midpoint between the distal and proximal portions of the optical fiber 1000. The outer cladding 1008 may have a second thickness at the distal portion of the optical fiber 1000. The second thickness may be less than the first thickness. The second thickness may be selected such that the propagation pattern of the illumination light extends to the outer edge of the outer cladding 1008 at the distal portion of the optical fiber 1000. At least a portion of the illumination light may exit the optical fiber 1000 at the distal portion of the optical fiber 1000.

[0073] To guide illumination light out of optical fiber 1000, the optical fiber may include a light redirector 606, such as a textured surface, which may violate the condition of total internal reflection, thus coupling some or all of the illumination light out of the distal portion of optical fiber 1000. The light redirector 606 has been described in detail above. As a specific example, outer cladding 1008 may have a textured outer edge at the distal portion of optical fiber 1000. The textured outer edge may guide at least some of the illumination light out of optical fiber 1000 at the distal portion of optical fiber 1000.

[0074] As a specific example Figure 12 An example end-face cross-sectional view of the fiber optic distal portion 1200 is shown. The fiber optic distal portion 1200 can be coupled with... Figure 1 It is used together with the optical fiber 118 in the endoscope 100.

[0075] Endoscope 100 may include an elongated endoscope body 102. Optical fiber 118 may extend along the endoscope body 102. Optical fiber 118 may be a multimode optical fiber. Optical fiber 118 may include a cladding layer 206 (… Figure 2 The core 202 surrounded by ) Figure 2The core 202 and cladding 206 may have different refractive indices. The core 202 can guide the therapeutic light 116 and the illumination light 120 as guide light longitudinally along the optical fiber 118 to the distal portion of the endoscope body 102. The therapeutic light may have a longer wavelength than the illumination light. The optical fiber 118 may include a distal portion 1200 formed of a material 1204 having a substantially uniform refractive index. The distal portion 1200 can receive the guide light and propagate the guide light distally within the distal portion 1200 as unguided light. As the unguided light propagates distally within the distal portion 1200, it can extend radially to illuminate the sides of the distal portion 1200. A diffraction grating 1202 may be disposed on the sides of the distal portion 1200. The diffraction grating 1202 may have a grating spacing selected such that the following two conditions occur. First, the diffraction grating 1202 can couple at least some of the illumination light 120 from the distal portion 1200 of the optical fiber to a negative diffraction order (e.g., a negative first diffraction order). Second, the diffraction grating 1202 may not couple the treatment light 116 to a diffraction order. (For example, the grating spacing may be too small compared to the wavelength of the treatment light 116 to produce any non-zero diffraction order for the treatment light 116. Such a condition is mathematically described by the well-known grating equations.) As a result, the treatment light 116 can be reflected from the diffraction grating 1202 to remain in the distal portion 1200 of the optical fiber and exit the distal portion 1200 of the optical fiber through the distal end of the optical fiber 118.

[0076] Figure 13 It shows that it is suitable for Figure 1 A cross-sectional side view of an example of the distal portion 1300 of the optical fiber 1302 used in the endoscope 100. Figure 14 It shows Figure 13 End view of the distal end 1314 of optical fiber 1302.

[0077] Endoscope 100 may include an elongated endoscope body 102 ( Figure 1 Fiber optic cable 1302 may extend along the endoscope body 102. Fiber optic cable 1302 may longitudinally guide therapeutic and illumination light to the distal portion of the endoscope body 102. The therapeutic and illumination light may have different wavelengths.

[0078] A wavelength-sensitive optical splitter can be positioned at the distal end of optical fiber 1302. The wavelength-sensitive optical splitter can direct illumination light to exit laterally through the side of optical fiber 1302 at the distal end of optical fiber 1302. The wavelength-sensitive optical splitter can also allow therapeutic light to exit longitudinally through the distal end 1314 of optical fiber 1302.

[0079] In some examples, the wavelength-sensitive optical splitter may include a fiber Bragg grating 1304A disposed along the length of the distal portion of fiber 1302. The fiber Bragg grating 1304A may be formed by periodic and / or aperiodic variations in the refractive index of the fiber core 1306. Each transition between a relatively low refractive index and a relatively high refractive index can produce reflections in the fiber core 1306. These reflections can interfere with each other. For wavelengths that are in phase with each other (e.g., the center wavelength), the fiber Bragg grating 1304A can produce relatively large reflections in the fiber core 1306. For wavelengths that are out of phase with each other (e.g., wavelengths far from the center wavelength), the reflected light in the fiber core 1306 is relatively small. The Bragg grating 1304A can act as a wavelength-sensitive filter, which can reflect light relatively strongly at the center wavelength and relatively weakly at wavelengths far from the center wavelength. The center wavelength can be determined by the effective refractive index of the core and the period of the grating (e.g., the on-axis spacing of adjacent grating features 1308). The bandwidth of the reflection (e.g., the spectral width of the reflection peak in wavelength units) can be determined by the center wavelength, the difference between the relatively high and relatively low refractive indices, and a portion of the optical power contained in the fiber core 1306.

[0080] In a configuration in which the grating feature 1308 of the fiber Bragg grating 1304A is formed orthogonally to the longitudinal axis (LA) of the fiber 1302, reflections from the fiber Bragg grating 1304A remain in the fiber core 1306 and traverse the fiber 1302 in the opposite direction to the incident light (e.g., near-end propagation away from the distal end 1314 of the fiber 1302).

[0081] To configure the fiber Bragg grating 1304A to guide reflected light laterally out of the fiber 1302, for example, through the lateral edge of the fiber, the grating feature 1308 of the fiber Bragg grating 1304A can be positioned at an angle (e.g., non-orthogonal) relative to the longitudinal axis (LA) of the fiber 1302. Specifically, the grating feature 1308 of the fiber Bragg grating 1304A (e.g., a planar interface between a relatively high refractive index and a relatively low refractive index) can be tilted at a non-orthogonal angle relative to the longitudinal axis (LA) of the fiber 1302. This angle can guide the reflected light out of the fiber core 1306, through the fiber cladding 1310, and out of the fiber 1302 through the side of the fiber 1302.

[0082] In some examples, the fiber Bragg grating 1304A may include a beveled fiber Bragg grating 1304A. The beveled fiber Bragg grating 1304A can reflect at least one spectral portion of the illumination light to form a reflected light portion 1312A. The reflected light portion 1312A may be located in the visible portion of the electromagnetic spectrum. The beveled fiber Bragg grating 1304A allows the therapeutic light 116 to be transmitted through it. The therapeutic light 116 may be located in the infrared portion of the electromagnetic spectrum.

[0083] In some examples, the wavelength-sensitive optical splitter may include a plurality of beveled fiber Bragg gratings 1304A, 1304B, 1304C, and 1304D arranged sequentially along the length of the distal portion of fiber 1302. Using the sequential beveled fiber Bragg gratings 1304A, 1304B, 1304C, and 1304D allows illumination light to be guided out of fiber 1302 in multiple reflective portions 1312A, 1312B, 1312C, and 1312D. Using multiple reflective portions can optionally provide greater flexibility than reflecting all illumination light out of fiber 1302 in a single reflective portion.

[0084] In some examples, the individual angled fiber Bragg gratings of a plurality of angled fiber Bragg gratings 1304A, 1304B, 1304C, and 1304D can reflect the corresponding reflected portion 1312A, 1312B, 1312C, or 1312D of the illumination light out of the fiber core 1306, through the fiber cladding 1310, and out of the fiber 1302 through the side of the fiber 1302.

[0085] In some examples, at least two of the multiple beveled fiber Bragg gratings 1304A, 1304B, 1304C, and 1304D can have different grating spacings. Because the grating spacing at least partially determines the center wavelength reflected by the fiber Bragg grating, using two gratings with different spacings allows the fiber 1302 to reflect different spectral portions of the illumination light into different reflected light portions. For example, at least two of the multiple beveled fiber Bragg gratings 1304A, 1304B, 1304C, and 1304D can reflect different spectral portions of the illumination light. Specifically, the fiber 1302 can reflect a first spectral portion of the illumination light into a first reflected light portion 1312A and a second spectral portion of the illumination light into a first reflected light portion 1312B. Using multiple spectral portions allows the fiber 1302 to cover the spectral width of the illumination light using multiple fiber Bragg gratings with relatively small bandwidths. Fiber Bragg gratings with relatively small bandwidths are easier to manufacture than single fiber Bragg gratings with relatively large bandwidths that cover the full spectral width of the illumination light.

[0086] In some examples, at least two of the multiple angled fiber Bragg gratings 1304A, 1304B, 1304C, and 1304D can have the same grating spacing. Using the same grating spacing for two or more fiber Bragg gratings allows the corresponding reflective portions to have the same center wavelength. For example, by controlling the peak reflectance of the fiber Bragg grating by varying the refractive index difference between the gratings, the fiber can guide the same component of one spectral portion of the illumination light into multiple reflected light portions.

[0087] In some examples, at least two of the multiple angled fiber Bragg gratings 1304A, 1304B, 1304C and 1304D can be oriented at different azimuth positions around the longitudinal axis (LA) of fiber 1302, such that the corresponding reflective portions 1312A, 1312B, 1312C and 1312D of the illumination light are emitted from fiber 1302 at different azimuth positions. Figure 14 The example shows four reflective sections 1312A, 1312B, 1312C, and 1312D emanating from different azimuth positions, equidistant from each other at 90-degree intervals around the circumference of fiber 1302. Other azimuth positions and other numbers of fiber Bragg gratings and reflective sections can also be used. Figure 14 The end view only shows the azimuth position; it should be understood that the actual propagation directions of the reflecting parts 1312A, 1312B, 1312C and 1312D are included in the actual propagation directions. Figure 14 The propagation component toward the viewer causes the distance between the reflecting portion and the longitudinal axis (LA) to increase as the reflecting portion propagates along the positive Z direction (e.g., toward the viewer).

[0088] In some examples, at least two of the multiple angled fiber Bragg gratings 1304A, 1304B, 1304C, and 1304D can be angled at different angles, such that the corresponding reflective portions 1312A, 1312B, 1312C, and 1312D of the illumination light can exit from fiber 1302 at different propagation angles θ relative to the longitudinal axis (LA) of fiber 1302. Using different propagation angles θ allows fiber 1302 to guide the reflective portions 1312A, 1312B, 1312C, and 1312D of the illumination light to illuminate the same location of the target as needed, or to illuminate a particularly large area of ​​the target or a particularly small area of ​​the target.

[0089] In some examples, the angled fiber Bragg gratings in the plurality of angled fiber Bragg gratings 1304A, 1304B, 1304C, and 1304D can allow the therapeutic light 116 to be transmitted through them. For example, the angled fiber Bragg gratings can be relatively highly reflective of the center wavelength of the visible portion of the electromagnetic spectrum to reflect all or part of the illumination light, and relatively highly transmissive of the infrared portion of the electromagnetic spectrum to transmit all or part of the therapeutic light 116. In some examples, each of the plurality of angled fiber Bragg gratings 1304A, 1304B, 1304C, and 1304D can reflect a corresponding spectral portion of the illumination light that is in the visible portion of the electromagnetic spectrum. In some examples, each of the plurality of angled fiber Bragg gratings 1304A, 1304B, 1304C, and 1304D can transmit the therapeutic light 116 that is in the infrared portion of the electromagnetic spectrum.

[0090] Figure 15 An example of a method 1500 for delivering light in an endoscope is shown. This method can be comprised of... Figure 1-14 The procedure can be performed using an endoscope with the fiber optic configuration shown, or any suitable endoscope. Method 1500 is merely an example of a method for delivering light within an endoscope. Other suitable methods may also be used.

[0091] At operation 1502, the endoscope can guide the therapeutic and illumination beams longitudinally along the optical fiber to the distal portion of the slender endoscope body. The therapeutic and illumination beams can have different wavelengths.

[0092] At operation 1504, the endoscope can use a wavelength-sensitive light splitter to guide the illumination light laterally away from the fiber through the side of the fiber at the distal end of the fiber.

[0093] At operation 1506, the endoscope can allow the therapeutic light to exit the fiber longitudinally through the distal end of the fiber via a wavelength-sensitive light splitter.

[0094] In some examples, the wavelength-sensitive optical splitter may include a fiber Bragg grating disposed along the length of the distal portion of the optical fiber. In some examples, guiding the illumination light away from the optical fiber may include: using a fiber Bragg grating to reflect at least some of the illumination light out of the core of the optical fiber, through the cladding of the optical fiber, and out of the optical fiber through the side of the optical fiber.

[0095] In some examples, the wavelength-sensitive optical splitter may include a plurality of beveled fiber Bragg gratings arranged sequentially along the length of the distal portion of the optical fiber. In some examples, guiding the illumination light away from the optical fiber may include: using each of the plurality of beveled fiber Bragg gratings to reflect a corresponding portion of the illumination light away from the core of the optical fiber, through the cladding of the optical fiber, and out of the optical fiber through the side of the optical fiber.

[0096] In some examples, the wavelength-sensitive optical splitter may include a length of coreless fiber disposed at the distal portion of the optical fiber and a diffraction grating disposed on the side of the coreless fiber. In some examples, guiding the illumination light away from the optical fiber may include: guiding the therapeutic light and illumination light to emerge from the core of the optical fiber and enter the coreless fiber; propagating the therapeutic light and illumination light such that they expand radially in a tapered manner within the coreless fiber to illuminate the lateral edge of the coreless fiber and the diffraction grating; reflecting at least some of the therapeutic light with the diffraction grating; and transmitting at least some of the illumination light with the diffraction grating.

[0097] Example

[0098] To further illustrate the apparatus, related systems, and / or related methods discussed herein, a list of non-limiting examples is provided below. Each of the following non-limiting examples may exist independently or may be arbitrarily arranged or combined with any or more of the other examples.

[0099] In Example 1, the endoscope may include: an elongated endoscope body; and an optical fiber extending along the endoscope body, the optical fiber being configured to guide a treatment light and an illumination light longitudinally along the optical fiber to a distal portion of the endoscope body, the treatment light and the illumination light having different wavelengths, the endoscope including a wavelength-sensitive light splitter disposed at the distal portion of the optical fiber, and the wavelength-sensitive light splitter being configured to: guide the treatment light to exit the optical fiber longitudinally through the distal end of the optical fiber; and guide the illumination light to exit the optical fiber circumferentially along the side of the optical fiber passing through the distal portion of the optical fiber.

[0100] In Example 2, the endoscope of Example 1 may optionally be configured such that the wavelength-sensitive light splitter includes a dichroic thin film coating disposed on the side of the optical fiber at the distal end portion of the optical fiber, the dichroic thin film coating being configured to reflect at least some of the therapeutic light and transmit at least some of the illumination light.

[0101] In Example 3, the endoscope of any of Examples 1-2 may optionally be configured such that the optical fiber includes: a core extending along the length direction of the optical fiber, the core being formed of a core material having a core refractive index; and a cladding surrounding the core along the length direction of the optical fiber, the cladding being formed of a cladding material having a cladding refractive index less than that of the core; and wherein the distal portion of the optical fiber is formed of a material having a constant refractive index in a cross-sectional region of the optical fiber, the cross-section being orthogonal to the longitudinal axis of the optical fiber, such that therapeutic and illumination light emitted from the core is radially extended in a conical shape in the distal portion to irradiate the dichroic thin film coating.

[0102] In Example 4, the endoscope of any of Examples 1-3 may optionally be configured such that the optical fiber includes: a core extending along the length of the optical fiber, the core being formed of a core material having a core refractive index; and a cladding surrounding the core along the length of the optical fiber, the cladding being formed of a cladding material having a cladding refractive index less than that of the core; and the cladding having a first thickness at a midpoint between a distal portion and a proximal portion of the optical fiber; and the cladding having a second thickness at the distal portion of the optical fiber, the second thickness being less than the first thickness.

[0103] In Example 5, the endoscope of any of Examples 1-4 may optionally be configured such that the wavelength-sensitive light splitter includes a diffraction grating disposed on the side of the optical fiber at the distal portion of the optical fiber, the diffraction grating being configured to reflect at least some of the therapeutic light and transmit at least some of the illumination light.

[0104] In Example 6, the endoscope of any of Examples 1-5 may optionally be configured such that the diffraction grating has diffraction features spaced apart by a characteristic interval, the characteristic interval being selected such that at least some of the illumination light is transmitted through the diffraction grating with negative first-order transmission and such that the treatment light does not produce any diffraction order.

[0105] In Example 7, the endoscope of any of Examples 1-6 may optionally be configured such that the diffraction features are arranged orthogonally to the longitudinal axis of the optical fiber.

[0106] In Example 8, the endoscope of any of Examples 1-7 may optionally be configured such that the diffraction feature has a feature depth selected to improve the negative first-order diffraction efficiency of the illumination light.

[0107] In Example 9, the endoscope of any of Examples 1-8 may optionally be configured such that the optical fiber includes: a core extending along the length of the optical fiber, the core being formed of a core material having a core refractive index; and a cladding surrounding the core along the length of the optical fiber, the cladding being formed of a cladding material having a cladding refractive index less than that of the core; and wherein the distal portion of the optical fiber is formed of a material having a constant refractive index in a cross-sectional region of the optical fiber, the cross-section being orthogonal to the longitudinal axis of the optical fiber, such that therapeutic and illumination light emitted from the core is radially extended in a tapered manner in the distal portion to illuminate a wavelength-sensitive light splitter.

[0108] In Example 10, the endoscope of any of Examples 1-9 may optionally be configured such that the illumination light has at least one wavelength between 400 nm and 700 nm.

[0109] In Example 11, the endoscope of any of Examples 1-10 may optionally be configured such that the illumination light comprises a wavelength continuum, at least a portion of which is between 400 nm and 700 nm.

[0110] In Example 12, the endoscope of any of Examples 1-11 may optionally be configured such that the therapeutic light has a wavelength of the infrared portion of the electromagnetic spectrum.

[0111] In Example 13, the endoscope of any of Examples 1-12 may optionally be configured such that the therapeutic light has a wavelength corresponding to the emission wavelength of the pulsed thulium laser.

[0112] In Example 14, the endoscope of any of Examples 1-13 may optionally be configured such that the therapeutic light has a wavelength between 1810 nm and 2100 nm.

[0113] In Example 15, the endoscope of any of Examples 1-14 may optionally be configured such that the therapeutic light has a wavelength of approximately 1940 nm.

[0114] In Example 16, a method for delivering light in an endoscope may include: guiding a therapeutic light and an illumination light longitudinally along an optical fiber to a distal portion of the endoscope, the therapeutic light and the illumination light having different wavelengths; guiding the therapeutic light to exit the optical fiber longitudinally through the distal end of the optical fiber; and guiding the illumination light to exit the optical fiber circumferentially through the side of the optical fiber at the distal portion of the optical fiber.

[0115] In Example 17, the method of Example 16 may optionally further include: directing the therapeutic light and the illumination light to a wavelength-sensitive light splitter disposed at the distal portion of the optical fiber; reflecting the therapeutic light from the wavelength-sensitive light splitter toward the distal end of the optical fiber; and transmitting the illumination light through the wavelength-sensitive light splitter to exit the optical fiber circumferentially through the side of the optical fiber.

[0116] In Example 18, the method of any one of Examples 16-17 may optionally be configured such that the wavelength-sensitive light splitter includes a dichroic thin film coating disposed on the side of the optical fiber at the distal end portion of the optical fiber, the dichroic thin film coating being configured to reflect at least some of the therapeutic light and transmit at least some of the illumination light.

[0117] In Example 19, the method of any one of Examples 16-18 may optionally be configured such that the wavelength-sensitive light splitter includes a diffraction grating disposed on the side of the optical fiber at the distal portion of the optical fiber, the diffraction grating being configured to reflect at least some of the therapeutic light and transmit at least some of the illumination light.

[0118] In Example 20, the endoscope may include: an elongated endoscope body; an optical fiber extending along the endoscope body, the optical fiber being a multimode fiber and including a core surrounded by a cladding having a different refractive index from the cladding, the core being configured to longitudinally guide a therapeutic light and an illumination light as guide light along the optical fiber to a distal portion of the endoscope body, the therapeutic light having a longer wavelength than the illumination light, the optical fiber including a distal portion having a substantially uniform refractive index, the distal portion being configured to receive the guide light and propagate the guide light as an unguided light within the distal portion, the unguided light being configured to radially expand as it propagates within the distal portion to illuminate the sides of the distal portion; and a diffraction grating disposed transversely on the distal portion of the optical fiber, the diffraction grating having a grating spacing selected such that the diffraction grating couples at least some of the illumination light out of the distal portion of the optical fiber to a negative diffraction order; and the diffraction grating not coupling the therapeutic light to a diffraction order.

[0119] In Example 21, the endoscope may include: an elongated endoscope body; and an optical fiber extending along the endoscope body, the optical fiber being configured to guide a therapeutic light and an illumination light longitudinally along the optical fiber to a distal portion of the endoscope body, the therapeutic light and the illumination light having different wavelengths, the optical fiber including a first core configured to guide the therapeutic light to the distal portion of the endoscope, the optical fiber being configured to guide the therapeutic light to exit the optical fiber longitudinally through the distal end of the optical fiber, the optical fiber including a second core configured to guide the illumination light to the distal portion of the endoscope, the optical fiber being further configured to guide the illumination light to exit the optical fiber circumferentially through the side of the optical fiber at the distal portion of the optical fiber.

[0120] In Example 22, the endoscope of Example 21 may optionally be configured such that the first core extends along the longitudinal axis of the optical fiber; and the second core extends cylindrically around the first core.

[0121] In Example 23, the endoscope of any of Examples 21-22 may optionally be configured such that the first core and the second core are formed of a material having a first refractive index; and the optical fiber includes an inner cladding disposed between the first core and the second core, the inner cladding being formed of a cladding material having a second refractive index less than the first refractive index.

[0122] In Example 24, the endoscope of any of Examples 21-23 may optionally be configured such that the size of the inner cladding is suitable for isolating the therapeutic light from the second core and the illumination light from the first core.

[0123] In Example 25, the endoscope of any of Examples 21-24 may optionally be configured such that the optical fiber includes an outer cladding surrounding a second core, the outer cladding being formed of a cladding material.

[0124] In Example 26, the endoscope of any of Examples 21-25 may optionally be configured such that: the outer cladding has a first thickness at the midpoint between the distal portion and the proximal portion of the optical fiber; and the outer cladding has a second thickness at the distal portion of the optical fiber, the second thickness being less than the first thickness.

[0125] In Example 27, the endoscope of any of Examples 21-26 may optionally be configured such that: the second thickness is selected such that the propagation pattern of the illumination light extends to the outer edge of the outer cladding at the distal portion of the optical fiber; and at least some of the illumination light exits the optical fiber at the distal portion of the optical fiber.

[0126] In Example 28, the endoscope of any of Examples 21-27 may optionally be configured such that the outer cladding has a textured outer edge at the distal portion of the optical fiber, the textured outer edge being configured to guide at least some of the illumination light out of the optical fiber at the distal portion of the optical fiber.

[0127] In Example 29, the endoscope of any of Examples 21-28 may optionally be configured such that the first core and the second core extend substantially longitudinally along the optical fiber.

[0128] In Example 30, the endoscope of any of Examples 21-29 may optionally be configured such that: the first core and the second core are formed of a material having a first refractive index; and the optical fiber includes a cladding surrounding the first core and the second core, the cladding being formed of a cladding material having a second refractive index less than the first refractive index.

[0129] In Example 31, the endoscope of any of Examples 21-30 may optionally be configured such that the size of the cladding is suitable for isolating the therapeutic light from the second core and isolating the illumination light from the first core.

[0130] In Example 32, the endoscope of any of Examples 21-31 may optionally be configured such that: near the midpoint between the distal and proximal portions of the optical fiber, the second core is spaced apart from the outer edge of the cladding by a first interval; and at the distal portion of the optical fiber, the second core is spaced apart from the outer edge of the cladding by a second interval, the second interval being smaller than the first interval.

[0131] In Example 33, the endoscope of any of Examples 21-32 may optionally be configured such that: the second interval is selected such that the propagation pattern of the illumination light extends to the outer edge of the cladding at the distal portion of the optical fiber; and at least some of the illumination light exits the optical fiber at the distal portion of the optical fiber.

[0132] In Example 34, the endoscope of any of Examples 21-33 may optionally be configured such that the illumination light has at least one wavelength between 400 nm and 700 nm.

[0133] In Example 35, the endoscope of any of Examples 21-34 may optionally be configured such that the illumination light comprises a wavelength continuum, at least a portion of which is between 400 nm and 700 nm.

[0134] In Example 36, the endoscope of any of Examples 21-35 may optionally be configured such that the therapeutic light has a wavelength of the infrared portion of the electromagnetic spectrum.

[0135] In Example 37, the endoscope of any of Examples 21-36 may optionally be configured such that the therapeutic light has a wavelength corresponding to the emission wavelength of the pulsed thulium laser.

[0136] In Example 38, the endoscope of any of Examples 21-37 may optionally be configured such that the therapeutic light has a wavelength between 1810 nm and 2100 nm.

[0137] In Example 39, the endoscope of any of Examples 21-38 may optionally be configured such that the therapeutic light has a wavelength of approximately 1940 nm.

Claims

1. An endoscope, comprising The slender body of the endoscope; An optical fiber extending along the endoscope body is configured to guide therapeutic light and illumination light longitudinally along the optical fiber to a distal portion of the endoscope body, the therapeutic light and the illumination light having different wavelengths; as well as A wavelength-sensitive light splitter is disposed at the distal portion of the optical fiber, the wavelength-sensitive light splitter being configured to guide the illumination light to exit the optical fiber laterally through the side of the optical fiber at the distal portion of the optical fiber, and to allow the therapeutic light to exit the optical fiber longitudinally through the distal end of the optical fiber.

2. The endoscope according to claim 1, wherein, The wavelength-sensitive optical splitter includes a fiber Bragg grating disposed along the length of the distal portion of the optical fiber. The fiber Bragg grating is configured to reflect at least some of the illumination light out of the core of the fiber, through the cladding of the fiber, and out of the fiber through the side of the fiber.

3. The endoscope according to claim 2, wherein, The fiber Bragg grating includes a beveled fiber Bragg grating and is configured such that: At least one spectral portion of the illumination light is reflected from the fiber Bragg grating, wherein the reflected light is in the visible portion of the electromagnetic spectrum; and The therapeutic light is transmitted through the fiber Bragg grating and is located in the infrared portion of the electromagnetic spectrum.

4. The endoscope according to claim 1, wherein, The wavelength-sensitive optical splitter includes a plurality of angled fiber Bragg gratings arranged sequentially along the length of the distal portion of the optical fiber. A single angled fiber Bragg grating among the plurality of angled fiber Bragg gratings is configured to reflect a corresponding portion of the illumination light out of the core of the fiber, through the cladding of the fiber, and out of the fiber through the side of the fiber.

5. The endoscope according to claim 4, wherein, At least two of the plurality of angled fiber Bragg gratings have different grating spacings.

6. The endoscope according to claim 4, wherein, At least two of the plurality of angled fiber Bragg gratings are configured to reflect different spectral portions of the illumination light.

7. The endoscope according to claim 4, wherein, At least two of the plurality of angled fiber Bragg gratings are oriented at different azimuth angles around the longitudinal axis of the fiber, such that the corresponding reflected portions of the illumination light are emitted from the fiber at different azimuth angles.

8. The endoscope according to claim 7, wherein, At least two of the plurality of angled fiber Bragg gratings have the same grating spacing.

9. The endoscope according to claim 4, wherein, At least two of the plurality of angled fiber Bragg gratings are angled at different angles, such that the corresponding reflected portions of the illumination light are emitted from the fiber at different propagation angles relative to the longitudinal axis of the fiber.

10. The endoscope according to claim 4, wherein, The angled fiber Bragg grating of the plurality of angled fiber Bragg gratings is configured to transmit the therapeutic light through the angled fiber Bragg grating.

11. The endoscope according to claim 4, wherein, Each of the plurality of angled fiber Bragg gratings is configured to: The corresponding spectral portion of the illumination light reflected from the angled fiber Bragg grating, wherein the illumination light is in the visible portion of the electromagnetic spectrum; and The therapeutic light is transmitted through the angled fiber Bragg grating and is located in the infrared portion of the electromagnetic spectrum.

12. The endoscope according to claim 1, wherein, The wavelength-sensitive optical splitter includes: A coreless optical fiber of a certain length is disposed at the distal portion of the optical fiber, the coreless optical fiber allowing the therapeutic light and the illumination light emitted from the core of the optical fiber to extend radially in a tapered shape within the coreless optical fiber to illuminate the lateral edge of the coreless optical fiber; and A diffraction grating is disposed on the lateral edge of the coreless optical fiber, the diffraction grating being configured to reflect at least some of the therapeutic light and transmit at least some of the illumination light.

13. The endoscope according to claim 12, wherein, The diffraction grating has diffraction features spaced apart by characteristic intervals, such that at least some of the illumination light is transmitted through the diffraction grating.

14. The endoscope according to claim 13, wherein, The characteristic spacing produces negative first-order transmission for the illumination light; and The characteristic spacing does not produce any diffraction order for the therapeutic light.

15. A method for delivering light in an endoscope, the method comprising: The therapeutic light and the illumination light are guided longitudinally along the optical fiber to the distal portion of the slender endoscope body, the therapeutic light and the illumination light having different wavelengths; The illumination light is directed using a wavelength-sensitive optical splitter to exit the optical fiber laterally through the side of the fiber at the distal end of the fiber; and The wavelength-sensitive optical splitter allows the therapeutic light to exit the optical fiber longitudinally through the distal end of the fiber.

16. The method according to claim 15, wherein, The wavelength-sensitive optical splitter includes a fiber Bragg grating disposed along the length of the distal portion of the optical fiber. as well as Guiding the illumination light away from the optical fiber includes: The fiber Bragg grating is used to reflect at least some of the illumination light out of the core of the fiber, through the cladding of the fiber, and out of the fiber through the side of the fiber.

17. The method according to claim 15, wherein, The wavelength-sensitive optical splitter includes a plurality of angled fiber Bragg gratings arranged sequentially along the length of the distal portion of the optical fiber. as well as Guiding the illumination light away from the optical fiber includes: Each of the plurality of angled fiber Bragg gratings reflects a corresponding portion of the illumination light out of the core of the fiber, through the cladding of the fiber, and out of the fiber through the side of the fiber.

18. The method according to claim 15, wherein, The wavelength-sensitive optical splitter includes a coreless optical fiber of a certain length disposed at the distal portion of the optical fiber and a diffraction grating disposed on the lateral edge of the coreless optical fiber. as well as Guiding the illumination light away from the optical fiber includes: The therapeutic light and the illumination light are guided to exit from the core of the optical fiber and enter the coreless optical fiber; The therapeutic light and the illumination light are propagated such that they extend radially in a tapered manner in the coreless optical fiber to illuminate the lateral edge of the coreless optical fiber and the diffraction grating; At least some of the therapeutic light is reflected using the diffraction grating; and The diffraction grating is used to transmit at least some of the illumination light.

19. An endoscope comprising: The slender body of the endoscope; An optical fiber extending along the endoscope body is configured to guide infrared therapeutic light and visible illumination light longitudinally along the optical fiber to a distal portion of the endoscope body. as well as An angled fiber Bragg grating is disposed along the length of the distal portion of the optical fiber. The angled fiber Bragg grating is configured to reflect at least some of the visible illumination light out of the optical fiber through the side of the optical fiber, and to transmit the infrared therapeutic light through the angled fiber Bragg grating so as to exit the optical fiber longitudinally through the distal end of the optical fiber.

20. The endoscope of claim 19 further comprises a plurality of angled fiber Bragg gratings, the plurality of angled fiber Bragg gratings including the angled fiber Bragg gratings, the plurality of angled fiber Bragg gratings being sequentially arranged along the length direction of the distal portion of the optical fiber, each of the plurality of angled fiber Bragg gratings being configured to reflect a corresponding portion of the illumination light out of the core of the optical fiber, through the cladding of the optical fiber, and out of the optical fiber through the side of the optical fiber.

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