Multi-core fiber laser system

Abstract

Systems and methods for localizing and characterizing an anatomical target during a laser procedure are disclosed. A surgical laser system comprises a multi-core fiber that includes a first fiber core to transmit relatively high-power therapeutic laser, and a second fiber core to transmit a non-therapeutic, relatively low-power optical or electromagnetic signal and a return signal from the target responsive to the optical or electromagnetic irradiation thereon. The system can determine a fiber-to-target distance based on an interference pattern between the return signal and at least a portion of the optical or electromagnetic signal reflect by a reflective member of the optical fiber. The fiber-to-target distance, among other target characteristics, can be provided to a user or a mechanism for manual or automatic adjustment of laser fiber position or orientation or laser output setting.

Description

Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1MULTI-CORE FIBER LASER SYSTEMCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to the following U.S. Provisional Patent Applications: Serial No. 63 / 553,723, filed February 15, 2024; Serial No. 63 / 658,367, filed June 10, 2024; and Serial No. 63 / 658,358, filed June 10, 2024. The contents of these Provisional Patent Applications are incorporated herein by reference in their entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to endoscopic laser systems, and more specifically relates to a laser system including a multi-core fiber for directing therapeutic laser and a return signal from an anatomical target, and using at least the return signal for target characterization and / or laser treatment optimization.BACKGROUND

[0003] Endoscopes have been used in a variety of clinical procedures, including, for example, illuminating, imaging, detecting and diagnosing one or more disease states, providing fluid delivery (e.g., saline or other preparations via a fluid channel) toward an anatomical region, providing passage (e.g., via a working channel) of one or more therapeutic devices or biological matter collection devices for sampling or treating an anatomical region, and providing suction passageways for collecting fluids (e.g., saline or other preparations), among other procedures. Examples of such anatomical region can include gastrointestinal tract (e.g., esophagus, stomach, duodenum, pancreaticobiliary duct, intestines, colon, and the like), renal area (e.g., kidney(s), ureter, bladder, urethra) and other internal organs (e.g., reproductive systems, sinus cavities, submucosal regions, respiratory tract), and the like.

[0004] Some endoscopes include a working channel through which an operator can perform suction, placement of diagnostic or therapeutic devices (e.g., a brush, a biopsy needle or forceps, a stent, a basket, or a balloon), or minimally invasive surgeries such as tissue sampling or removal of unwantedClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 tissue (e.g., benign or malignant strictures) or foreign objects (e.g., calculi). Some endoscopes can be used with a laser or plasma system to deliver energy to a target structure (e.g., soft or hard tissue or calculi) to achieve desired treatment. For example, laser has been used in applications of tissue ablation, coagulation, vaporization, fragmentation, and lithotripsy to break down calculi in kidney, gallbladder, ureter, among other stone-forming regions, or to ablate large calculi into smaller fragments.SUMMARY

[0005] When a surgical laser system is used to treat various diseases and conditions, the position of a target structure to be treated with respect to a laser fiber for delivering therapeutic laser is an important factor that may determine a successful procedure. In many cases, such relative position of the target structure can be represented by a distance between a distal end of the laser fiber (or a distal tip of a device such as an endoscope integrating the laser fiber) and the target structure, hereinafter referred to as “fiber-to-targef ’ distance. In tissue ablation procedures, for example, if the laser fiber is positioned too close to the target structure, then one or more of laser flashing, fiber degradation, or tissue sticking may occur. If the laser fiber is positioned too far from the target structure, then more energy will be required to achieve a desired tissue therapeutic effect.

[0006] Conventionally, an ideal or optimal fiber-to-target distance is achieved mostly based on an operator’s (e.g., an endoscopist’s) “best guess.” This puts a high demand on the operator’s experience, and may introduce interoperator or inter-institution variations, particularly in difficult cases where the treatment target has complicated structures, compositions, or shapes, or when the treatment target is situated at hard-to-access locations. Manual positioning of the laser fiber to search for an ideal fiber-to-target distance may take significant amount of time and effort, cause fatigue in the operator, and reduce productivity, especially when laser fiber repositioning is constantly required during the procedure to treat complicated targets.

[0007] The present inventor has recognized an unmet need for apparatus and techniques to automatically localize the treatment target with respect to theClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 laser fiber, such as to measure a fiber-to-target distance, and to reposition the laser fiber as necessary to deliver therapeutic laser more effectively to the target during a laser procedure. The present document describes a multi-core optical fiber for directing a therapeutic laser beam to a target structure, and for transmitting a return signal from the target structure to a feedback-control device that can determine a fiber-to-target distance, and adjust laser fiber position and / or laser output setting according to the fiber-to-target distance. In accordance with one embodiment, the multi-core fiber comprises a first fiber core having a relatively large core diameter to transmit relatively high-power therapeutic laser beam (e.g., Holmium: YAG or Thulium fiber laser), and a second fiber core having a relatively smaller core diameter yet a high signal to noise ratio (SNR) when transmitting a non-therapeutic signal, such as the return signal from the target in response to a relatively low-power optical or electromagnetic (EM) signal irradiating on the target. The first fiber core can be a multi-mode fiber (MMF) core. The second fiber core can be a single-mode fiber (SMF) core. The return signal, optionally along with other optical signals or sensor information, may be used for fiber-to-target distance measurement, target identification, and / or laser therapy optimization, among other applications.

[0008] In accordance with one embodiment, the multi-core optical fiber as described above may be a part of a surgical laser system, which further includes a laser system to generate a relatively high-power therapeutic laser beam, and a controller circuit. The first fiber core (e.g., MMF core) can be optically coupled to the laser system and to direct the therapeutic laser beam to a target structure in a patient. The second fiber core (e.g., SMF core) can transmit a return signal from the target structure in response to an optical or EM signal irradiating on the target structure. The controller circuit can determine a characteristic of the target structure based at least in part on the return signal. The characteristic of the target structure may include at least one of a fiber-to- target distance between a distal end of the multi-core optical fiber and the target structure, a pressure experienced by the distal end of the multi-core optical fiber, a temperature at the distal end of the multi-core optical fiber, or a location or an orientation of the distal end of the multi-core optical fiber. The determined characteristic can be provided to a user interface or a robotic system to allow for manual or automatic adjustment of a position or an orientation of the distal endClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 of the optical fiber relative to the target structure, or a laser output setting of the laser system, based on the determined characteristic.

[0009] In accordance with another embodiment, a surgical laser system can determine a position or an orientation of an optical fiber using interferometry -based techniques. The surgical laser system includes a laser system to generate a relatively high-power therapeutic laser beam for treating a target structure in a patient, a non-therapeutic signal source to generate an optical or EM signal with relatively low energy. The therapeutic laser beam and the optical or EM signal can be directed to the target structure via an optical fiber, such as the multi-core fiber as described above. The surgical laser system includes a controller circuit to determine a fiber-to-target distance between a distal end of the optical fiber and the target structure based at least in part on (i) a portion of the optical or electromagnetic signal reflected by an at least partially reflective surface of the optical fiber, and (ii) a return signal from the target structure in response to the optical or electromagnetic signal irradiating on the target structure. In an example, the fiber-to-target distance may be determined based on an interference metric between the return signal and the portion of the optical or EM signal reflected by an at least partially reflective member of the optical fiber. The controller circuit may use the fiber-to-target distance in feedback control of laser fiber position and orientation, and / or laser output setting, during a laser procedure, such as controlling the laser system to deliver the therapeutic laser beam to the target structure when the fiber-to-target distance is within a specific range.

[0010] Example l is a multi-core optical fiber, comprising: a first fiber core configured to be coupled to a surgical laser system to direct a relatively high-power therapeutic laser beam to a target structure in a patient; and a second fiber core configured to transmit a return signal from the target structure in response to a relatively low-power optical or electromagnetic signal irradiating on the target structure.

[0011] In Example 2, the subject matter of Example 1 optionally includes the first fiber core that can include a multi-mode fiber (MMF), the second fiber core includes a single-mode fiber (SMF), the MMF having a larger diameter than the SMF.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1

[0012] In Example 3, the subject matter of Example 2 optionally includes the MMF that has a diameter within a range of 100-500 micrometers.

[0013] In Example 4, the subject matter of any one or more of Examples 2-3 optionally includes the SMF that has a diameter within a range of 5-10 micrometers.

[0014] In Example 5, the subject matter of any one or more of Examples 2-4 optionally include the MMF that can be configured to direct the relatively high-power therapeutic laser beam to a calculi target to produce an ablation or fragmentation effect thereon.

[0015] In Example 6, the subject matter of any one or more of Examples 1-5 optionally includes the first fiber core and the second fiber core that are configured to extend in parallel along a length of the multi-core optical fiber.

[0016] In Example 7, the subject matter of any one or more of Examples 1-6 optionally includes the first fiber core that can be configured to extend along a central longitudinal axis of the multi-core optical fiber.

[0017] In Example 8, the subject matter of any one or more of Examples 1-7 optionally includes the multi-core optical fiber that can include an outer jacket layer, and an intermediate cladding layer disposed between the first fiber core and the outer jacket layer, wherein the second fiber core is disposed within the intermediate cladding layer.

[0018] In Example 9, the subject matter of any one or more of Examples 1-8 optionally includes a central longitudinal axis of the first fiber core being offset from a central longitudinal axis of the multi-core optical fiber.

[0019] Example 10 is a surgical laser system, comprising: a laser system configured to generate a relatively high-power therapeutic laser beam; a multicore optical fiber, including a first fiber core configured to be optically coupled to the laser system and to direct the relatively high-power therapeutic laser beam to a target structure in a patient, and a second fiber core configured to transmit a return signal from the target structure in response to a relatively low-power optical or electromagnetic signal irradiating on the target structure; and a controller circuit configured to determine a characteristic of the target structure based at least in part on the return signal.

[0020] In Example 11, the subject matter of Example 10 optionally includes the characteristic of the target structure comprising at least one of aClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 fiber-to-target distance between a distal end of the multi-core optical fiber and the target structure, a pressure experienced by the distal end of the multi-core optical fiber, a temperature at the distal end of the multi-core optical fiber, an orientation of the distal end of the multi-core optical fiber, or a location of the distal end of the multi-core optical fiber.

[0021] In Example 12, the subject matter of any one or more of Examples 10-11 optionally includes the controller circuit that can be configured to, based at least in part on the determined characteristic of the target, generate a control signal to adjust a position or an orientation of a distal end of the multicore optical fiber relative to the target structure, and / or to adjust a therapeutic laser output setting.

[0022] In Example 13, the subject matter of any one or more of Examples 10-12 optionally includes the first fiber core of the multi-core optical fiber including a multi-mode fiber (MMF), the second fiber core of the multicore optical fiber including a single-mode fiber (SMF), the MMF having a larger diameter than the SMF.

[0023] In Example 14, the subject matter of any one or more of Examples 10-13 optionally includes the first fiber core and the second fiber core that can be configured to extend in parallel along a length of the multi -core optical fiber.

[0024] In Example 15, the subject matter of any one or more of Examples 10-14 optionally includes the multi-core optical fiber including an outer jacket layer, and an intermediate cladding layer disposed between the first fiber core and the outer jacket layer, wherein the second fiber core is disposed within the intermediate cladding layer.

[0025] In Example 16, the subject matter of any one or more of Examples 10-15 optionally include the second fiber core that can be further configured to transmit the relatively low-power optical or electromagnetic signal from a non-therapeutic signal source to the target structure.

[0026] In Example 17, the subject matter of any one or more of Examples 10-16 optionally includes the relatively low-power optical or electromagnetic signal that can be a non-therapeutic laser beam having a lower energy than the relatively high-power therapeutic laser beam, wherein the return signal includes a return laser signal.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1

[0027] In Example 18, the subject matter of any one or more of Examples 10-17 optionally includes a sensor configured to sense at least one of a pressure or a temperature at the target structure, wherein the controller circuit is configured to, based at least in part on the sensed pressure and / or temperature, generate a control signal to adjust a position or an orientation of a distal end of the multi-core optical fiber relative to the target structure, and / or to adjust a therapeutic laser output setting.

[0028] In Example 19, the subject matter of any one or more of Examples 10-18 optionally includes the controller circuit that can be configured to generate a control signal to a mechanism coupled to the multi-core optical fiber to automatically adjust a position or an orientation of a distal end of the multi-core optical fiber relative to the target structure based on the determined characteristic of the target structure.

[0029] In Example 20, the subject matter of any one or more of Examples 10-19 optionally includes a user interface that can be configured to present to a user the determined characteristic and a recommendation to adjust a position or an orientation of a distal end of the multi -core optical fiber relative to the target structure.

[0030] In Example 21, the subject matter of any one or more of Examples 10-20 optionally includes a central longitudinal axis of the first fiber core being offset from a central longitudinal axis of the multi-core optical fiber.

[0031] Example 22 is a method of operating a surgical laser system during a laser procedure in a patient. The method comprises steps of: directing a relatively high-power therapeutic energy via a first fiber core of a multi-core optical fiber to a target structure; directing a relatively low-power optical or electromagnetic signal through a second fiber core of the multi -core optical fiber to the target structure, and receiving a return signal from the target structure via the second fiber core; determining a characteristic of the target structure based at least in part on the return signal; and determining whether or not to adjust (i) a position or an orientation of a distal end of the multi -core optical fiber relative to the target structure and / or (ii) a power of the relatively high-power therapeutic energy based at least in part on the determined characteristic of the target structure.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1

[0032] Example 23 is a surgical laser system, comprising: a laser system configured to generate a therapeutic laser beam for treating a target structure in a patient; a non-therapeutic signal source configured to generate an optical or electromagnetic signal; an optical fiber configured to direct (i) the therapeutic laser beam and (ii) the optical or electromagnetic signal to the target structure; and a controller circuit configured to: determine a fiber-to-target distance between a distal end of the optical fiber and the target structure based at least in part on (i) a portion of the optical or electromagnetic signal reflected by an at least partially reflective surface of the optical fiber, and (ii) a return signal from the target structure in response to the optical or electromagnetic signal irradiating on the target structure; and generate a control signal to the laser system to deliver the therapeutic laser beam to the target structure when the fiber-to-target distance is within a specific range.

[0033] In Example 24, the subject matter of Example 23 optionally includes the at least partially reflective surface reflecting the portion of the optical or electromagnetic signal that can include a distal end face of the optical fiber.

[0034] In Example 25, the subject matter of any one or more of Examples 23-24 optionally include an interferometer optically coupled to the optical fiber and configured to generate an interference metric using the return signal and the portion of the optical or electromagnetic signal reflected by the at least partially reflective surface of the optical fiber, wherein the controller circuit is configured to determine the fiber-to-target distance based at least in part on the generated interference metric.

[0035] In Example 26, the subject matter of any one or more of Examples 23-25 optionally include an optical component inscribed in the optical fiber at a pre-determined distance from a proximate end of the optical fiber, wherein the controller circuit is further configured to determine the fiber-to- target distance based at least in part on a portion of the optical or electromagnetic signal reflected from the optical component.

[0036] In Example 27, the subject matter of Example 26 optionally includes the optical component which can be a fiber Brag grating.

[0037] In Example 28, the subject matter of any one or more of Examples 23-27 optionally include the optical fiber which can be a multi-coreClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 optical fiber comprising (i) a first fiber core optically coupled to the laser system and configured to direct the therapeutic laser beam to the target structure, and (ii) a second fiber core optically coupled to the non-therapeutic signal source and configured to direct the optical or electromagnetic signal to the target structure.

[0038] In Example 29, the subject matter of Example 28 optionally includes the second fiber core that can be configured to further direct the return signal and the portion of the optical or electromagnetic signal reflected by the at least partially reflective surface of the optical fiber to an interferometer.

[0039] In Example 30, the subject matter of any one or more of Examples 28-29 optionally includes the first fiber core that can be a multi-mode fiber (MMF), the second fiber core includes a single-mode fiber (SMF), the MMF having a larger diameter than the SMF.

[0040] In Example 31, the subject matter of any one or more of Examples 28-30 optionally includes a central longitudinal axis of the first fiber core being offset from a central longitudinal axis of the multi-core optical fiber.

[0041] In Example 32, the subject matter of any one or more of Examples 28-31 optionally includes the first fiber core that can be configured to direct the therapeutic laser beam to a calculi target to produce an ablation or fragmentation effect thereon.

[0042] In Example 33, the subject matter of any one or more of Examples 23-32 optionally includes a beam splitter configured to optically split the optical or electromagnetic signal into first and second split signals, wherein the first split signal is directed through a first optical path having a predetermined known length to a reflector, wherein the second split signal is directed through a second optical path to the target structure.

[0043] In Example 34, the subject matter of Example 33 optionally includes the controller circuit that can be configured to determine the fiber-to- target distance based at least in part on (i) a first return signal from the reflector in response to the first split signal and (ii) a second return signal from the target structure in response to the second split signal.

[0044] In Example 35, the subject matter of any one or more of Examples 23-34 optionally includes the controller circuit that can be configured to provide the determined fiber-to-target distance to a user interface for allowing a user to adjust, based at least in part on the fiber-to-target distance, at least oneClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 of (i) a position or an orientation of the distal end of the optical fiber relative to the target structure, or (ii) a therapeutic laser output setting of the laser system.

[0045] In Example 36, the subject matter of any one or more of Examples 23-35 optionally includes the controller circuit that can be configured to provide the determined fiber-to-target distance to the controller circuit for automatically adjusting, based at least in part on the fiber-to-target distance, at least one of (i) a position or an orientation of the distal end of the optical fiber relative to the target structure, or (ii) a therapeutic laser output setting of the laser system.

[0046] Example 37 is a method of operating a surgical laser system during a laser procedure in a patient. The method comprises steps of: directing a therapeutic laser beam and an optical or electromagnetic signal through an optical fiber to a target structure; in response to the optical or electromagnetic signal irradiating on the target structure, receiving (i) a portion of the optical or electromagnetic signal reflected by an at least partially reflective surface of the optical fiber and (ii) a return signal from the target structure; determining a fiber- to-target distance between a distal end of the optical fiber and the target structure based at least in part on (i) the received portion of the reflected optical or electromagnetic signal and (ii) the return signal; and delivering the therapeutic laser beam to the target structure when the fiber-to-target distance is within a specific range.

[0047] In Example 38, the subject matter of Example 37 optionally includes generating, via an interferometer optically coupled to the optical fiber, an interference metric between the return signal and the portion of the optical or electromagnetic signal reflected by the at least partially reflective surface of the optical fiber, wherein determining the fiber-to-target distance is based at least in part on the generated interference metric.

[0048] In Example 39, the subject matter of any one or more of Examples 37-38 optionally includes directing the optical or electromagnetic signal to an optical component inscribed in the optical fiber at a pre-determined distance from a proximate end of the optical fiber, wherein determining the fiber-to-target distance is based at least in part on a portion of the optical or electromagnetic signal reflected from the optical component.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1

[0049] In Example 40, the subject matter of any one or more of Examples 37-39 optionally includes directing the therapeutic laser beam through a first fiber core of a multi-core optical fiber, the first core having a central longitudinal axis offset from a central longitudinal axis of the multi -core optical fiber, wherein directing the optical or electromagnetic signal is through a second fiber core of the multi -core optical fiber.

[0050] In Example 41, the subject matter of Example 40 optionally includes, via the second fiber core of the multi-core optical fiber, directing (i) the return signal, and (ii) the portion of the optical or electromagnetic signal reflected by the at least partially reflective surface of the optical fiber to an interferometer.

[0051] In Example 42, the subject matter of any one or more of Examples 37-41optionally includes the therapeutic laser beam that can include a lithotripsy laser beam delivered to a calculi target to produce an ablation or fragmentation effect thereon.

[0052] In Example 43, the subject matter of any one or more of Examples 37-42 optionally includes optically splitting the optical or electromagnetic signal into first and second split signals using a beam splitter; directing the first split signal through a first optical path having a pre-determined known length to a reflector; and directing the second split signal through a second optical path to the target structure.

[0053] In Example 44, the subject matter of Example 43 optionally includes determining the fiber-to-target distance based at least in part on a first return signal from the reflector in response to the first split signal and a second return signal from the target structure in response to the second split signal.

[0054] In Example 45, the subject matter of any one or more of Examples 37-44 optionally includes providing the determined fiber-to-target distance to a user interface for allowing a user to adjust, based at least in part on the fiber-to-target distance, at least one of (i) a position or an orientation of the distal end of the optical fiber relative to the target structure, or (ii) a therapeutic laser output setting of the laser system.

[0055] In Example 46, the subject matter of any one or more of Examples 37-45 optionally includes automatically adjusting, via a control mechanism and based at least in part on the fiber-to-target distance, at least oneClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 of (i) a position or an orientation of the distal end of the optical fiber relative to the target structure using a mechanism, or (ii) a therapeutic laser output setting of the laser system.

[0056] The systems, devices, and techniques as described in accordance with various embodiments in this document, may be used in various endoscopy procedures involving laser treatment of tissue or other targets, including, for example, colonoscopy, anoscopy, arthroscopy, bronchoscopy, colonoscopy, colposcopy, cystoscopy, esophagoscopy, gastroscopy, laparoscopy, laryngoscopy, neuroendoscopy, proctoscopy, sigmoidoscopy, thoracoscopy etc.

[0057] This summary is an overview of some of the teachings of the present application and not intended to be an exclusive or exhaustive treatment of the present subject matter. Further details about the present subject matter are found in the detailed description and appended claims. Other aspects of the disclosure will be apparent to persons skilled in the art upon reading and understanding the following detailed description and viewing the drawings that form a part thereof, each of which are not to be taken in a limiting sense. The scope of the present disclosure is defined by the appended claims and their legal equivalents.BRIEF DESCRIPTION OF DRAWINGS

[0058] Various embodiments are illustrated by way of example in the figures of the accompanying drawings. Such embodiments are demonstrative and not intended to be exhaustive or exclusive embodiments of the present subject matter.

[0059] FIG. l is a block diagram illustrating an example of a laser energy delivery system configured to provide laser treatment to a target structure of a subject.

[0060] FIG. 2 is a block diagram illustrating a surgical laser system to provide a feedback-controlled laser treatment of a target using feedback information.

[0061] FIG. 3 illustrates an example of a feedback-controlled endoscopic surgical laser system with automatic fiber-to-target distance measurement and optical fiber position control.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1

[0062] FIGS. 4A-4B illustrate a cross-sectional view and an isometric view of a multi-core optical fiber for use in laser ranging applications such as measuring a fiber-to-target distance.

[0063] FIGS. 5A-5C illustrate examples of interferometry -based laser ranging system for measuring a fiber-to-target distance.

[0064] FIG. 6 illustrates an exemplary computer-based clinical decision support system (CDSS) that is configured to determine a proper laser output setting or a desired laser fiber location or orientation.

[0065] FIG. 7 is a flow chart illustrating an example method of measuring a fiber-to-target distance and using the same for controlling laser treatment of a target.

[0066] FIG. 8 is a flow chart illustrating an example method of measuring a fiber-to-target distance using interferometry techniques.

[0067] FIG. 9 is a block diagram illustrating an example machine upon which any one or more of the techniques (e.g., methodologies) discussed herein may perform.DETAILED DESCRIPTION

[0068] Described herein are systems, devices, and methods for localizing and characterizing an anatomical target during a laser procedure are disclosed. A surgical laser system comprises a multi-core fiber that includes a first fiber core to transmit relatively high-power therapeutic laser, and a second fiber core to transmit a non-therapeutic, relatively low-power optical or electromagnetic signal and a return signal from the target responsive to the optical or electromagnetic irradiation thereon. The system can determine a fiber-to-target distance based on an interference pattern between the return signal and at least a portion of the optical or electromagnetic signal reflect by a reflective member of the optical fiber. The fiber-to-target distance, among other target characteristics, can be provided to a user or a mechanism for manual or automatic adjustment of laser fiber position or orientation or laser output setting.

[0069] FIG. l is a block diagram illustrating an example of a laser energy delivery system 100 configured to provide laser treatment to a target structure 122 in an anatomical environment of a subject, such as anatomical structure (e.g., soft tissue, hard tissue, or abnormal such as cancerous tissue) orClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 calculi structure (e.g., kidney or pancreobiliary or gallbladder stone). In some examples, the laser energy delivery system 100 may deliver precisely controlled therapeutic treatment of tissue or other anatomical structures (e.g., tissue ablation, coagulation, vaporization, or the like) or treatment of non-anatomical structures (e.g., ablation or dusting of calculi structures).

[0070] The laser energy delivery system 100 can include a feedback control system 101, and at least one laser system in operative communication with the feedback control system 101. By way of example and not limitation, FIG. 1 shows the laser feedback system connected to a first laser system 102 and optionally (shown in dotted lines) to a second laser system 104. Additional laser systems are contemplated within the scope of the present disclosure. The first laser system 102 may include a first laser source 106, and associated components such as power supply, display, cooling systems and the like. The first laser system 102 may also include a first optical pathway 108 operatively coupled with the first laser source 106. In an example, the first optical pathway 108 includes an optical fiber. The first optical pathway 108 may be configured to transmit laser beams from the first laser source 106 to the target structure 122.

[0071] The feedback control system 101 may receive feedback signals 130 from the target. In an example, the feedback signals 130 may include signals indicative of target characteristics or surgical site conditions. In an example, the feedback signals 130 may include an acoustic signal produced by a laser pulse propagating through the media (e.g., liquid and vapor), projecting to the target and causing the target to vibrate. In another example, the feedback signals 130 may include reflected electromagnetic signal (e.g., reflected illumination light emitted from a light source). In an example, the feedback signals 130 may include images or video frames of at least a portion of the surgical site such as generated by an imaging sensor during a procedure. In yet another example, the feedback signals 130 may include a return laser signal in response to laser pulses irradiating on the target. The laser pulses may be generated by the first laser system 102 or the second laser system 104 in accordance with a specific output setting, such as a chirped laser. The return laser signal may be used for determining whether the target is within the laser firing range, as will be described further below with respect to FIGS. 2-3.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1

[0072] The feedback signals 130 may be used to control laser delivery, laser energy output, and / or other system parameters to improve therapy efficacy and to achieve or maintain a desired condition at the target site. In an example, the feedback control system 101 may analyze the feedback signals 130 to determine one or more target characteristics. Based on the determined target characteristics, the feedback control system 101 may identify target type or composition, adjust a laser output setting (e.g., one or more laser irradiation parameters such as power, duration, frequency, pulse shape, exposure time, or firing angle) or other system parameters, and generate and deliver laser pulses to the target in accordance with the laser output setting to achieve a desired therapeutic effect or to maintain a desired condition. For instance, the feedback control system 101 may monitor properties of the target structure during a therapeutic procedure (e.g., ablating calculi such as kidney stones into smaller fragments) to determine if the tissue was suitably ablated prior to another therapeutic procedure (e.g., coagulation of blood vessels). In another example, the feedback control system 101 may analyze the feedback signals 130 to automatically determine a distance between a distal end of the laser fiber and the target tissue to be treated, also referred to as a “fiber-to-targef ’ distance in this document. The fiber-to-distance may be used to guide manual or autonomous positioning of the laser fiber (e.g., advancing or retracting, or changing an orientation of, the distal end of the laser fiber) to achieve more efficient laser treatment of the target.

[0073] In an example, the first laser source 106 may be configured to provide a first output 110. The first output 110 may extend over a first wavelength range, such as one that corresponds to a portion of the absorption spectrum of the target structure. The first output 110 may provide effective ablation and / or carbonation of the target structure since the first output 110 is over a wavelength range that corresponds to the absorption spectrum of the tissue.

[0074] In an example, the first laser source 106 may be configured such that the first output 110 emitted at the first wavelength range corresponds to high absorption (e.g., exceeding about 250 cm’1) of the incident first output 110 by the tissue. In example aspects, the first laser source 106 may emit first output 110 between about 1900 nanometers (nm) and about 3000 nm (e.g.,Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 corresponding to high absorption by water) and / or between about 400 nm and about 520 nm (e.g., corresponding to high absorption by oxy- hemoglobin and / or deoxy-hemoglobin). Appreciably, there are two main mechanisms of light interaction with a tissue: absorption and scattering. When the absorption of a tissue is high (absorption coefficient exceeding 250 cm’1) the first absorption mechanism dominates, and when the absorption is low (absorption coefficient less than 250 cm’1), for example lasers at 800-1100 nm wavelength range, the scattering mechanism dominates.

[0075] Various commercially available medical-grade laser systems may be suitable for the first laser source 106. Examples of laser source 106 may include UV-VIS emitting InxGai-xN semiconductor lasers such as GaN laser with emission at 515-520 nm, InxGai-xN laser with emission at 370-493 nm, GaxAh-xAs laser with emission at 750-850 nm, or InxGai-xAs laser with emission at 904-1065 nm, among others. Alternatively, infrared (IR) lasers such as those summarized in Table 1 below may be used.Table 1 : Example List of suitable IR lasersLaser Wavelength Absorption Coefficient Optical PenetrationI (nm) pa(cm1) Depth5 (pm)Thulium fiber laser: 1908 88 / 150 114 / 67Thulium fiber laser: 1940 120 / 135 83 / 75Thulium: YAG: 2010 62 / 60 161 / 167Holmium: YAG: 2120 24 / 24 417 / 417Erbium: YAG: 2940 12,000 / 1,000 1 / 10

[0076] The optional second laser system 104 may include a second laser source 116 for providing a second output 120, and associated components, such as power supply, display, cooling systems and the like. The second laser system 104 may either be operatively separated from or, in the alternative, operatively coupled to the first laser source 106. In some embodiments, the second laser system 104 may include a second optical pathway 118 (separate from the first optical pathway 108) operatively coupled to the second laser source 116 for transmitting the second output 120. Alternatively, the first optical pathway 108 may be configured to transmit both the first output 110 and the second output 120.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1

[0077] In certain aspects, the second output 120 may extend over a second wavelength range, distinct from the first wavelength range. Accordingly, there may not be any overlap between the first wavelength range and the second wavelength range. Alternatively, the first wavelength range and the second wavelength range may have at least a partial overlap with each other. In advantageous aspects of the present disclosure, the second wavelength range may not correspond to portions of the absorption spectrum of the target structure where incident radiation is strongly absorbed by tissue that has not been previously ablated or carbonized. In some such aspects, the second output 120 may advantageously not ablate uncarbonized tissue. In another embodiment, the second output 120 may ablate carbonized tissue that has been previously ablated. In additional embodiments, the second output 120 may provide additional therapeutic effects. For instance, the second output 120 may be more suitable for coagulating tissue or blood vessels.

[0078] FIG. 2 is a block diagram illustrating a surgical laser system 200 to provide a feedback-controlled laser treatment of a target using feedback information, including but not limited to, fiber-to-target distance measurements. The system 200 can be an embodiment of the laser energy delivery system 100 for treating target structures of various types, or a lithotripsy system for destructing hardened masses like kidney stones, bezoars, gallstone, among other calculi structures.

[0079] The surgical laser system 200 may include a feedback control system 210, one or more sensors or data receivers 220, a laser system 230, a non-therapeutic signal source 240, a user interface 250, an actuator 260, and an optical fiber 270. The laser system 230, which is an example of the laser system 102 or the laser system 104 shown in FIG. 1, can include a laser source 232 (which can be an example of the first laser source 106 or the second laser source 116). The laser source 232 may generate laser pulses in accordance with an output setting, which may include one or more laser irradiation parameters (e.g., intensity, power, duration, frequency, or pulse shape, exposure time, or firing angle). At least some of the laser irradiation parameters are programmable or adjustable either automatically such as by the controller circuit 218, or manually by a user via the user interface 250. The laser pulses may be used for therapeutic purposes, such as for surgically removing or sampling tissue or ablating a calculiClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 structure. In some examples, the laser source 232 may generate non-therapeutic laser pulses for measuring a fiber-to-target distance, as described in this document in accordance with various embodiments. In some examples, the laser source 232 may include distinct laser sources, including a first laser source (such as the first laser source 106 shown in FIG. 1) to generate the relatively high- power therapeutic laser pulses, and a second lase source (such as the second laser source 116 shown in FIG. 1) to generate relatively low-power non- therapeutic laser pulses that may be used for estimating a fiber-to-target distance. In this document, by way of example and not limitation, the “relatively high- power” therapeutic laser pulses can be within a range of 2-60 watts, the “relatively low-power” non-therapeutic laser pulses (or other types of optical or electromagnetic energies) can be within a range of 1-100 milliwatts.

[0080] Laser pulses generated by the laser source 232 may be directed to the target structure 122 via the optical fiber 270, which can be an embodiment of the first optical pathway 108 or the second optical pathway 118. In an example, the optical fiber 270 is a multi-core fiber comprising a first fiber core optically coupled to the laser system 230 to direct a relatively high-power therapeutic laser beam therefrom to the target structure 122, and a second fiber core optically coupled to the feedback control system 210 to transmit thereto a return signal from the target structure 122. The return signal can be generated in response to an optical or EM signal (such as generated by the non-therapeutic signal source 240) irradiating on the target structure 122. In some examples, the second fiber core may be optically coupled to the non-therapeutic signal source 240 to transmit the optical or EM signal directed to the target structure 122. In some examples, the second fiber core may transmit sensor data (e.g., pressure or temperature information at the target site) collected by the one or more sensors or data receivers 220 which may be located at a distal portion of the optical fiber 270. Examples of the multi-core optical fiber are described further below with respect to FIGS. 4A-4B.

[0081] The feedback control system 210, which is an embodiment of the feedback control system 101 shown in FIG. 1, can include a feedback analyzer 212 and a controller circuit 218. According to example embodiments, the feedback control system 210, or a part thereof (such as the feedback analyzer 212 and / or the controller circuit 218) may include processors, such asClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components for performing one or more of the functions attributed to the feedback control system 210.

[0082] The feedback analyzer 212 may be communicatively coupled to one or more sensors or data receivers 220. The return signal from the target structure 112 in response to an optical or EM signal (e.g., a non-therapeutic laser) irradiating thereon, a portion of the optical or EM signal reflected from an at least partially reflective surface of the optical fiber 270 or from an at least partially reflective member integrated into or affixed to the optical fiber 270 (such as a fiber Bragg grating (FBG), as will be described further below), and / or sensor data collected by the one or more sensors or data receivers 220, may be transmitted to the feedback analyzer 212 via the optical fiber 270. In an example, at least some of the above-mentioned signals may be transmitted to the feedback analyzer 212 via a fiber core of the optical fiber 270, such the SMF core 420 of the multi-core optical fiber 400 as illustrated in FIGS. 4A-4B. The feedback analyzer 212 may use the feedback information to determine a target characteristic, which may include, for example, at least one of a fiber-to-target distance between a distal end of the optical fiber 270 and the target structure, a pressure experienced by the distal end of the optical fiber 270, a temperature at the distal end of the optical fiber 270, or a location or an orientation of the distal end of the optical fiber 270. Based at least on the determined target characteristic, the feedback analyzer 212 may determine whether or not to reposition the distal end of the optical fiber 270 relative to the target structure 122, and / or to adjust a laser output setting of the laser system 230 to provide appropriate laser treatment. By way of example and not limitation and as illustrated in FIG. 2, the one or more sensors or data receivers 220 may include an imaging sensor 222 and a return signal detector 224. The imaging sensor 222 can be included in an imaging system that further includes a lens system.Examples of the imaging sensor 222 can include a CCD or CMOS camera sensitive in ultraviolet (UV), visible (VIS) or infrared (IR) wavelengths. The imaging sensor 222 can be located a distal portion of an endoscope for use during the procedure, an example of which is illustrated in FIG. 3. The imagingClient File #: GAP24082-URJD-WO1 Dkt #: 5409.938WO1 sensor 222 may obtain an imaging signal of at least a portion of the target structure 122 during the procedure. In an example, the non-therapeutic signal source 240 can generate and direct electromagnetic radiation at the target structure 122, and the imaging sensor 222 can obtain the imaging signal in response to the electromagnetic radiation incident on the target structure 122. Table 2 below shows examples of the non-therapeutic signal source 240 as applicable to the examples discussed herein.Table 2: Light sources for spectroscopic system

[0083] The return signal detector 224 may detect and receive a return signal from the target structure 122 in response to an optical or EM signal irradiating on the target structure 122 generated by the non-therapeutic signal source 240. In an example, the optical or EM signal can include non-therapeutic laser. The non-therapeutic laser may have less power than the relatively high- power therapeutic laser emitted from the laser source 232. The return signal detector 224 may be positioned at the distal end of the optical fiber 270 in proximity of the fiber tip from which the optical or EM signal is emitted. In an example, the optical or EM signal may include a chirped laser, also known as a frequency-swept laser, which has a time-varying instantaneous frequency. TheClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 laser system 230 can include an optical splitter that splits the chirped laser into a first portion directed to and irradiating on the target structure 122, and a second portion being kept local and does not travel to the target structure 122. The return laser signal from the target, in response to the first portion irradiating on the target, can be detected, and interferometrically recombined with the second portion of the chirped laser. Other mechanisms for automatic adjusting fiber position or orientation are contemplated..

[0084] Other sensor types or modalities may be included in the one or more sensors or data receivers 220 to sense information about the target or its surrounding environment. In one example, a pressure sensor 226 may be included to sense a pressure signal from the target structure 122. In another example, a temperature sensor 228 may be included to sense a temperature signal at the target structure 122. Such sensors may be disposed at a distal portion of the optical fiber 270. The sensed information (e.g., pressure or temperature) may be used to a position or an orientation of the distal end of the multi-core optical fiber relative to the target structure, or to adjust a therapeutic laser output setting.

[0085] The sensed information, including one or more of the imaging signal obtained by the imaging sensor 222, the return signal detected and received by the return signal detector 224, signals reflected by an at least partially reflective surface of the optical fiber 270 or reflected by an at least partially reflective member integrated into or affixed to the optical fiber 270 (such as an FBG as will be described further below with respect to FIGS. 3 and 5C), or pressure or temperature information sensed respectively by the pressure sensor 226 and the temperature sensor 228, may be provided to the feedback analyzer 212. The feedback analyzer 212 includes one or more of a spectrometer 213, a target identification circuit 214, an interferometer 215, and a fiber-to- target distance estimator 216. The spectrometer 213 may determine one or more spectroscopic properties from the imaging signal of the target, such as reflectivity, absorption index, among other spectral properties. Examples of the spectrometer 213 may include a Fourier Transform Infrared spectrometer (FTIR), a Raman spectrometer, a UV-VIS reflection spectrometer, a UV-VIS-IR spectrometer, a fluorescent spectrometer, and the like. The FTIR is a method used for routine, easy and rapid materials analysis. This technique has relativelyClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 good spatial resolution and gives information about the chemical composition of the material. The Raman spectroscopy has good accuracy in identifying hard and soft tissue components. As a high spatial resolution technique, it is also useful for determining distribution of components within a target. The UV-VIS reflection spectroscopy is a method that gathers information from the light reflected off an object similar to the information yielded from the eye or a color image made by a high-resolution camera, but more quantitatively and objectively. The reflection spectroscopy offers information about the material since light reflection and absorption depends on its chemical composition and surface properties. It is also possible to get unique information about both surface and bulk properties of the sample using this technique. The reflection spectroscopy can be a valuable technique to recognize composition of hard or soft tissue. The fluorescent spectroscopy is a type of electromagnetic spectroscopy that analyzes fluorescence from a sample. It involves using a beam of light, usually ultraviolet, that excites a material compound and causes the material compound to emit light, typically in visible or IR area. The method is applicable for analysis of some organic components such as hard and soft tissue.

[0086] The target identification circuit 214 may identify in vivo a type or composition of the target structure 122 (or a specific portion thereof) during the procedure using the one or more spectroscopic properties determined by the spectrometer 213. In endoscopic laser therapy, it is desirable to identify target type and composition, apply appropriate laser energy only to treatment target (e.g., cancerous tissue, or a particular calculus type) while avoiding or reducing laser irradiation at non-treatment tissue (e.g., normal tissue). Conventional target identification generally requires collecting a sample of the target for in vitro analysis. Continuous monitoring and automatic in vivo tissue identification at the tip of the endoscope may advantageously reduce surgery time and complexity, give physicians more information to better adapt the treatment during the procedure, and improve therapy efficacy. For example, in laser lithotripsy that applies laser to break apart or dust calculi, automatic and in vivo recognition of calculi of a particular type (e.g., chemical composition of a kidney or pancreobiliary or gallbladder stone) and distinguishing it from surrounding tissue would allow a physician to adjust a laser setting (e.g., power, exposure time, or firing angle) to more effectively ablate the target stone, while at theClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 same time avoiding irradiating neighboring non-treatment tissue. Commonly assigned U.S. Patent Application No. 16 / 947,488, entitled “LASER FIBER-TO- TARGET DISTANCE CONTROL,” describes example methods of identifying or classifying different target structures, such as different compositions of kidney stones (e.g., calcium oxalate stone (Monohydrate), calcium oxalate stone (Dihydrate), calcium phosphate stone, struvite stone, and uric acid stone) using spectroscopic data, the description of which is hereby incorporated by reference in its entirety.

[0087] The fiber-to-target distance estimator 216 may estimate a distance between a distal end of the optical fiber 270 and the target structure 122 (the “fiber-to-target distance”) based at least in part on the return signal transmitted through the optical fiber 270. In an example, the fiber-to-target distance may be determined or estimated using interferometry techniques. Interferometry makes use of the principle of superposition to combine lights or electromagnetic (EM) waves in a way that will cause the result of their combination to have some meaningful properties that are di gnostic of the original state of the input lights or EM waves. In particular, when two input lights or FM waves with the same frequency combine, the resulting intensity pattern is determined by the phase difference therebetween. Lights or EM waves that are in phase will undergo constructive interference, and lights or EM waves that are out of phase (e.g., with half a cycle phase difference) will undergo destructive interference. Lights or EM waves that are not completely in phase nor completely out of phase will have an intermediate intensity. This produces an interference fringe pattern. The relative phase difference between the two input lights or EM waves can be used to derive information about the difference in optical path lengths travelled by the two input lights or EM: waves.

[0088] As illustrated in FIG. 2, the fiber-to-target distance estimator 216 can be coupled to the interferometer 215. The interferometer 215 can generate one or more interference metrics using at least two signals selected from a return signal in response to the optical or EM signal irradiating on the target structure 122, a reflected portion of the optical or EM signal from an at least partially reflective surface of the optical fiber 270, or a reflected portion of the optical or EM signal from an at least partially reflective member integrated into or affixed to the optical fiber 270 (such as an FBG as will be described further below). InClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 an example, the interferometer 215 can generate one or more interference metrics from an interference pattern between the return signal and a portion of the optical or EM signal reflected by a distal end face of the optical fiber 270. The return signal and the reflected signal portion may be transmitted to the interferometer 215 via a fiber core of the optical fiber 270, such as the SMF core of a multi-core optical fiber, as will be discussed further with respect to FIGS. 4A-4B.

[0089] The interferometer 215 may include a dual -path interferometer. A dual-path interferometer is one in which a reference beam and a sample beam travel along different paths. The reference beam and the sample beam may be split from a light or EM wave from a single source. After being perturbed by interaction with the sample under test, the sample beam is recombined with the reference beam to create an interference pattern, which can then be interpreted and determine a path difference. The interferometer 215 may additionally or alternatively include a common-path interferometer (also referred to as singlepath interferometer). A common-path interferometer is a class of interferometer in which the reference beam and sample beam travel along the same path to interfere. Although travelling along the same path, the reference and sample beams may travel along opposite directions, or they may travel along the same direction but with the same or different polarization. Double-path interferometers are highly sensitive to phase shifts or length changes between the reference and sample arms at least attributed to the dedicated and easily controllable reference path. Comparatively, common-path interferometers are generally more robust to environmental vibrations than double-path interferometers. Additionally, common-path interferometers generally have simpler and more compact setup. Examples of the interferometer 215 and interferometry -based tip-to-target distance measurement are described below with reference to FIGS. 3 and 5A-5C.

[0090] In an example, the fiber-to-target distance estimator 216 may estimate the fiber-to-target distance based on a coherence metric between the return laser signal from the target and the second portion of the chirped laser split from the chirped laser pulses. The optical coherence metric may involve an interferogram and analysis of frequency components of the interferogram. The optical coherence-based distance measurement method is also known asClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 frequency modulated continuous wave (FMCW) method, which has been implemented in LiDAR (light detection and ranging) scanner and found vast object ranging applications in land management and planning, hazard assessment, forestry, agriculture, geologic mapping, or watershed and river surveys In various examples, to improve estimation accuracy and consistency, the fiber-to-target distance measurements may be post-processed to remove outliers, such as the overestimates caused by air bubbles or other interfering objects in the fluid space along the light path. The optical coherence-based estimation of fiber-to-target distance and outlier removal techniques, as described in commonly owned U.S. Provisional Patent Application No. 63 / 580,161, entitled “LASER FIBER RANGING BASED ON OPTICAL COHERENCE TOMOGRAPHY,” is hereby incorporated by reference in its entirety.

[0091] In various examples, the feedback analyzer 212, or one or more components therein such as the target identification circuit 214 and / or the fiber- to-target distance estimator 216, may identify target type or composition, determine a proper laser output setting or a desired laser fiber location or orientation using artificial intelligence (Al) or machine learning (ML) based techniques. For example, information about the identified type or composition of the target structure may be applied to a trained ML model to automatically determine a proper laser output setting or a desired laser fiber position or orientation during the procedure. In some examples, sensor data from the sensor circuitry 220 may be applied directly to one or more trained ML models that output a proper laser output setting or a laser fiber location or orientation. Examples of the trained ML models are discussed below with respect to FIG. 6.

[0092] The controller circuit 218 may be coupled by wired or wireless connections to the feedback analyzer 212. The controller circuit 218 may control the laser system 230 according to one or more control algorithms described herein to control the laser output of the laser source 232. In some examples, the feedback analyzer 212 may continuously monitor the target structure 122, and continuously communicate with the controller circuit 218 to provide feedback control signals to adjust laser output, such as by increasing or decreasing the pulse amplitude, pulse rate, power intensity, duration, frequency, pulse shape, exposure time, among other laser irradiation parameters. The controller circuitClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1218 may continue maintaining the laser system 230 in a particular state (with a particular output) until a change in feedback is detected. For example, when the target identification circuit 214 detects a different target type or composition based on spectroscopic properties from the spectrometer 213, the controller circuit 218 may adjust the laser output of the laser source 232. In an example, for a renal stone with a hard surface with a first composition and a softer core of a second composition, continuous tissue composition through the target identification allows a first higher laser output to be used to dust the hard surface of a renal stone, and after dusting automatically or upon user confirmation switching to a different lower laser output to ablate the soft core of the stone. As an alternative to the automatic adjustment of laser output, in some examples, the controller circuit 218 may adjust the laser output in a commanded mode, in which case the controller circuit 218 may present to a user (e.g., a surgeon or an endoscopist) current laser output and information about identified target type or composition via a user interface, and recommend the user to adjust the laser output to produce desired therapeutic effect on the target structure 122.

[0093] In addition to the target identification information (e.g., target type or composition), the controller circuit 218 may control the laser system 230 to deliver laser energy to the target structure 122 further based on the estimated fiber-to-target distance. For example, if the target structure 122 is identified as an intended treatment structure type (e.g., a specified soft tissue type or a specified calculus type), and if the fiber-to-target distance (d) satisfies a condition (e.g., falling below a threshold dth or within a specified laser firing range), then the laser pulses may be delivered to the target structure 122. However, if the target structure 122 is not within the laser firing range (e.g., d> dth), then the controller circuit 218 may produce a control signal to temporarily “lock” the laser source 232, such that no laser pulses are emitted to the target until the target structure 122 is within the laser firing range. The estimated fiber- to-target distance and an indication that the target structure 122 is out of laser firing range (d>dth) may be presented to the user on a user interface. The user may adjust the optical fiber 270 such as repositioning the distal end of the optical fiber 270 to move closer to the target.

[0094] In some examples, the controller circuit 218 may generate a control signal to a mechanism coupled to the optical fiber 270 to automaticallyClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 adjust the position or the orientation of the distal end of the optical fiber 270 with respect to the target structure 122. One example of such mechanism, as illustrated in FIG. 2, is an actuator 260 that may, in response to the control signal from the controller circuit 218, automatically advance or retract the optical fiber or change an orientation (e.g., an aiming angle) of the distal end of the optical fiber 270 with respect to the target structure 122. In an example, the controller circuit 218 may adjust the position or the orientation of the distal end of the optical fiber based on the identified target type or composition. A desired or optimal distance or range of distance for firing laser at the target may depend on multiple factors including the target type or composition, target location and surrounding anatomy, laser setting, procedure type, or desired tissue effect. As described above, laser output may be adjusted manually or automatically based on target type or composition, such that different portions of the target (e.g., the surface and the core of a calculi structure with respective different compositions) may be treated using different laser outputs. In addition or alternative to the adjustment of laser output, in some examples, the position or the orientation of the distal end of the optical fiber may be adjusted based on target type or composition. In an example of laser lithotripsy, as the target identification circuit 214 continuously analyzes the target type and composition, the controller circuit 218 may control the actuator 260 to advance the distal end of the optical fiber 270 closer to a renal stone target in response to an identification of a hard surface of the target to better dust the stone surface. In response to an identification of a soft core of the stone target, the actuator 260 control the actuator 260 to retract the distal end of the optical fiber 270 further away from the renal stone target. Other mechanisms for adjusting fiber position or orientation are contemplated. Commonly assigned U.S. Provisional Patent Application No. 63 / 581,900, entitled “ENGAGABLE ACTUATION MECHANISM,” describes examples of engageable steering actuators capable of providing both angulation and rotation, the description of which is hereby incorporated by reference in its entirety.

[0095] The user interface 250 may be operatively in communication with the feedback control system 210. The user interface 250 can include a display unit to display information including, for example, surgical site conditions such as images, pressure, or other information sensed by the one or more sensors orClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 data receivers 220, information generated by the feedback analyzer 212 including the target identification and estimated fiber-to-target distance, and current device settings such as the laser output setting. The display unit can display UI elements including visual elements, alerts, tactile feedback, or any combination thereof. In some examples, the user interface 250 may generate an alert if the fiber-to-target distance exceeds a threshold or a specific range. The alert can be presented in an audible, visible, tactile, or otherwise human- perceptible format. The user interface 250 may include one or more input units to receive user programming of various components of the surgical laser system 200, such as parameter values used for identifying target type or composition, estimating a fiber-to-target distance, and laser output setting. In some examples, the display unit may generate recommendations for adjusting the position or the orientation of the distal end of the optical fiber 270, or for adjusting laser output or other system parameters. A user may use the one or more input units to confirm, reject, or modify any of the recommended adjustments.

[0096] FIG. 3 illustrates an example of a feedback-controlled endoscopic surgical laser system 300 with automatic fiber-to-target distance measurement and fiber position adjustment. The system 300 can be an example implementation of the surgical laser system 200. The system 300 may include an endoscope 301, a feedback control system 310, a laser source 332, a multi-core optical fiber 334, and a robotic device such as an actuator 338. The endoscope 301 has a proximal portion and an elongate distal portion configured to be inserted into a surgical site of a patient during an endoscopy procedure. The endoscope 301 may provide visual inspection or treatment of soft (e.g., noncal cified) or hard (e.g., calcified) targets, including but not limited to calculi structures. As illustrated in FIG. 3, the endoscope 301 may include or provide visualization and illumination optics, such as a visualization optical pathway 360 and an illumination optical pathway 350, each of which may extend longitudinally along the elongate body of the endoscope 301. In some examples, one or more of the visualization optical pathway 360 or the illumination optical pathway 350 may be integrated into or affixed to the multi-core optical fiber 334, implemented within a common fiber core (e.g., the SMF core as illustrated in FIGS. 4A-4B), or separate fiber cores (e.g., the SMF core and the MMF core). An eyepiece or camera or imaging display may be provided at or coupled to theClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 visualization optical pathway 360 to permit user or machine visualization of a target region at or near a distal end of the endoscope 301. The target region may be illuminated by light 370, such as provided by an illumination light source 324 at a proximal end of the illumination optical pathway 350 and emitted from a distal end of the illumination optical pathway 350. The light source 324, which is an embodiment of the non-therapeutic signal source 240 of FIG. 2, can include, for example, a Xenon lamp, a light-emitting diode (LED), a laser diode, or any combination thereof. In an example, the light source 324 may include two or more light sources that emit light having different illumination characteristics, referred to as illumination modes. In an example, the illumination modes may include a white light illumination mode, or a special light illumination mode such as a narrow band imaging mode, an auto fluorescence imaging mode or an infrared imaging mode. A special light illumination can concentrate and intensify specific wavelengths of light, for example, resulting in a better visualization of tissue or other structures at the surgical site.

[0097] The endoscopic surgical laser system 300 may include or be coupled to the laser source 332, which may be an example of the first laser source 106 or the second laser source 116 in FIG. 1, or the laser source 232 in FIG. 2. The laser source 332 may be mechanically and optically connected to the multi-core optical fiber 334. In some examples, the laser source 332 may include a first laser source (such as the first laser source 106 shown in FIG. 1) configured to generate therapeutic laser pulses (also referred to as the treatment beam) for surgically removing or sampling tissue or ablating a calculi structure, and a second lase source (such as the second laser source 116 shown in FIG. 1) to generate non-therapeutic laser pulses used for estimating a fiber-to-target distance. The therapeutic laser pulses and the non-therapeutic laser pulses can be directed to the target structure 122 through the same or a different optical pathways.

[0098] The multi-core optical fiber 334, which is an embodiment of the first optical pathway 108 or the second optical pathway 118 in FIG. 1, or the optical fiber 270 in FIG. 2, may be introduced via a proximal access port of the endoscope 301, and extend within a working channel or other longitudinal passage or lumen of the endoscope 301 or similar instrument. The multi-core optical fiber 334 may include a MMF core optically coupled to the laser sourceClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1332 to direct a relatively high-power therapeutic laser beam to the target structure 122, and a SMF core to transmit a return signal 385A from the target structure 122. The return signal 385A can be generated in response to an optical or EM signal (e.g., the non-therapeutic laser pulses) irradiating on the target structure 122. In some examples, as the optical or EM signal travels along the multi-core fiber 334, a portion of the optical or EM signal may get reflected by an at least partially reflective surface, such as a distal end face 336 of the multicore optical fiber 334. In some other examples, a portion of the optical or EM signal may be reflected from an at least partially reflective member integrated into or affixed to the multi-core optical fiber 334, such as a fiber Bragg grating (FBG) 390 inscribed in a fiber core, such as the SMF core, of the multicore optical fiber 334. An FBG is an is a type of distributed Bragg reflector constructed in a short segment of a fiber core in which the index of refraction within the fiber core segment changes along its length, from high- index to low-index. Thi s modulation of the refractive index within an FBG can be a steady periodic change or a variable “quasi -periodic” change. If an FBG contains regions with different periods, a single optical fiber can contain multiple “mirrors,” causing different wavelengths of light to reflect from different positions along the fiber. The change in the period of the index modulation along the length of the fiber does not need to be abrupt. The modulation of the refractive index causes an FBG to act like a wavelengthspecific dielectric mirror that reflects certain wavelengths and transmits others. The wavelength that an FBG reflects depends on the spacing between the high index and low index regions within the fiber. The FBG 390 can be inscribed in a fiber core (e.g., the SMF core) at a pre-determined distance proximal to the distal end 336 of the multi-core fiber 334.

[0099] The reflected signal portion 385B by the distal end face 336 and the reflected signal portion 385C by the FBG 390 may be directed to the feedback analyzer 312 via the multi-core optical fiber 334, such as through the SMF core therewithin. As will be described further below with respect to FIGS. 5A-5C, one or more of return signal 385 A, the reflected signal portion 385B by the distal end face, or the reflected signal portion 385C by the FBG 390, may be used in interferometry -based laser ranging applications, such as estimating the fiber-to-target distance.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1

[0100] The endoscopic surgical laser system 300 can include a camera or imaging device 325. The camera or imaging device 325 can include an imaging sensor (such as the imaging sensor 222 in FIG. 2) that can generate an imaging signal 365 of the target in response to electromagnetic radiation (e.g., illumination light 370) of the target at or near the surgical site. The camera or imaging device 325 can be a CCD or CMOS camera, or a laser scanning device. As illustrated in FIG. 3, the target structure 122 is within the view of the camera or imaging device 325, such that in response to the electromagnetic radiation, the camera or imaging device 325 may collect the signal reflected from target structure 122 and produce an imaging signal 365 of the target structure 122. The imaging signal 365 may be transmitted through the optical pathway 360, or alternatively through the multi-core optical fiber 334, to the feedback control system 310 (which is an example of the feedback control system 210). In an example, the multi-core optical fiber 334 can concurrently direct the optical or EM signal 383, the return signal 385A, and the imaging signal 365. The feedback control system 310 can include a feedback analyzer 312 and a controller circuit 318. In an example, the imaging signal may pass through an optical splitter before reaching the feedback analyzer 312. The feedback analyzer 312, which is an example of the feedback analyzer 212 in FIG. 2, may include a spectrometer that may generate one or more spectroscopic properties from the imaging data. The feedback analyzer 312 may identify the target as one type of tissue or one type of calculi of distinct compositions using the one or more spectroscopic properties, as described above with respect to FIG. 2.

[0101] The feedback analyzer 312 may determine a characteristic of the target structure 122, including, for example, at least one of a fiber-to-target distance between a distal end of the multi-core optical fiber 334 and the target structure, a pressure experienced by the distal end of the multi-core optical fiber 334, a temperature at the distal end of the multi-core optical fiber 334, an orientation of the distal end of the multi-core optical fiber 334, or a location of the distal end of the multi-core optical fiber 334 . In an example, the fiber-to- target distance may be measured using interferometry techniques. Examples of interferometry -based laser ranging system for measuring a fiber-to-target distance are discussed below with respect to FIGS. 5A-5C. In another example, the fiber-to-target distance may be measured using a FMCW method. A chirpedClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 excitation laser (an example of the optical or EM signal 383) can be emitted from the laser source 332, a portion of the chirped laser irradiating on the target structure 122 produces the return signal 385A, and a coherence metric may be calculated between the chirped excitation laser and the return signal 385 A, as described above with respect to FIG. 2.

[0102] The controller circuit 318 may generate a control signal to the laser source 332 to adjust an output setting for the therapeutic laser pulse. The adjustment of the therapeutic laser output setting can be based at least in part on the identified target type or composition. In some examples, the adjustment of the therapeutic laser output setting may further be based on the determined fiber- to-target distance. For example, the controller circuit 318 may temporarily “lock” the laser source 332 to prevent it from firing laser pulse if the estimated fiber-to-target distance exceeds a threshold range.

[0103] The controller circuit 318 can additionally or alternatively generate a control signal to a robotic device to adjust a position or an orientation of the distal end 336 of the multi-core optical fiber 334. The robotic device, such as the actuator 338, can be coupled to a portion of the multi-core optical fiber 334, and can be in electrical communication with the controller circuit 318. In an example, the actuator 338 may be located at or near the distal end of the endoscope 301. The actuator 338 may include one or more of an electromagnetic element, an electrostatic element, a piezoelectric element, or other actuating element such as to actuate or otherwise permit longitudinal or rotational positioning of the distal end 336 of the multi-core optical fiber 334 with respect to the working channel or other longitudinal passage of the endoscope 301, or with respect to another reference location for which the endoscope 301 may serve as a frame of reference. Based at least in part on the identified target type or composition, the controller circuit 318 can activate the actuator 338 to adjust the position or the orientation of a distal end 336 of the multi-core optical fiber 334, such as adjusting the longitudinal position by advancing or retracting the distal end 336 to respectively increase or decrease a distance to the target structure 122, or adjusting the rotational position by steering the distal end 336 to increase or decrease the aiming angle with respect to the target structure 122. Such adjustment of the position or the orientation of a distal end of the optical fiber can improve efficacy of laser treatment while preserving laser energy.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1

[0104] FIGS. 4A-4B illustrate a cross-sectional view (FIG. 4 A) and an isometric view (FIG. 4B) of a multi-core optical fiber 400 (an embodiment of the optical fiber 270) for use in laser ranging applications such as measuring a fiber- to-target distance. The multi-core optical fiber 400 comprises a multi-mode fiber (MMF) core 410 and a single-mode fiber (SMF) core 420. The MMF core 410 and the SMF core 420 may extend substantially in parallel along a length of the multi-core optical fiber 400. In the illustrated example, the MMF core 410 may extend along the central longitudinal axis of the multi -core optical fiber 400. The MMF core 410 may be coupled to the laser source 232 to direct a relatively high-power therapeutic laser beam to the target structure 122, such as HolmiunrYAG or Thulium fiber laser for ablating calculi structures in kidney or other body locations. The MMF core 410 has a relatively large core diameter so as to transmit a large amount of therapeutic laser power, which is desired in calculi ablation applications. In one example, the MMF core 410 has a diameter within a range of 100-500 micrometers. In an example, a central longitudinal axis of the MMF core 410 is offset from a central longitudinal axis of the multicore optical fiber 400. The SMF core 420 may be coupled to the feedback back analyzer 212, and transmit thereto the return signal from the target structure 122 and / or sensor signals collected from the target structure 122. The SMF core 420 may additionally direct an optical or EM signal (e.g., a non-therapeutic laser) to the target structure 122. In some examples, the SMF core may transmit portions of the optical or EM signal reflected from an at least partially reflective surface within the optical fiber, or reflected from an integrated or affixed reflective member. An example of such optional integrated reflective member, as shown in FIG. 4B, is a fiber Bragg grating (FBG) 490 (an embodiment of the FBG 390 as shown in FIG. 3) inscribed in the SMF core 420 at a pre-determined distance proximal to the distal end of the optical fiber. The SMF has an advantage of preserving a high signal to noise ratio (SNR) during signal transmission. The SMF core 420 has a much smaller diameter than the MMF core 410. In one example, the SMF core 420 has a diameter within a range of 5-10 micrometers.

[0105] As illustrated, the multi-core optical fiber 400 may include an outer jacket layer 430 and an intermediate cladding layer 440. The outer jacket layer 430, which may be made of polymer or other materials (e.g., quartz), can provide resilient support of the MMF core 410 and the SMF core 420 within theClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 fiber, and protect said cores from the external environment during the procedure. In some examples, the jacket layer 430 may be covered with a resin coating layer made of, for example, silicone resin, UV curable resin, polyimide resin, etc. to further provide guaranteed strength and resilience. The intermediate cladding layer 440 may be disposed between an exterior of the MMF core 410 and the outer jacket layer 430. The SMF core 420 may be disposed within the intermediate cladding layer 440. The intermediate cladding layer 440 may be made of either pure quartz glass or fluorine or otherwise doped quartz glass. In an example, the cladding layer 440 may be made of dopped silicon dioxide (also known as silica), which may prevent or reduce dissipation of laser or other optical signals (e.g., due to scattering, absorption, or diffraction) while being transmitted through the MMF core 410 (e.g., relatively high-power therapeutic laser directed to the target structure 122) and / or the SMF core 420 (e.g., optical or EM signal directed to the target structure 122).

[0106] FIGS. 5A-5C illustrate examples of interferometry -based laser ranging system for measuring or estimating a fiber-to-target distance using a dual-path interferometer (FIG. 5A) or a common-path interferometer (FIGS. 5B and 5C). The systems illustrated therein are embodiment of at least a portion of the surgical laser system 200. FIG. 5A illustrates a system 500A configured to measure the fiber-to-target distance using a dual-path interferometer 540. Also included in the system 500A are a beam splitter 510, a reference path 520, a test path 530, and a fiber-to-target distance estimator 560. The beam splitter 510 can split an optical or EM signal 583 (e.g., a non-therapeutic laser emitted from the laser source 532) into a first split signal 583A and second split signal 583B. The first split signal 583 A, also referred to as the reference beam, is a reflected signal. The second split signal 583B, also referred to as the test beam, is a transmitted signal passing through the beam splitter 510. By way of example and not limitation, 5-20% of the optical or EM signal 583 may get reflected, and the rest gets transmitted through the beam splitter 510.

[0107] The first split signal 583A can be directed through the reference optical path 520 to the dual-path interferometer 540. The reference optical path 520 can have a pre-determined known length. Along the reference optical path 520 can include an optical circulator 521 and a reflector 522. The optical circulator 521 can pass the first split signal 583A from one optical fiber toClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 another (i.e., the reference path 520). It is a non-reciprocal device routing the light based upon the direction of light propagation. The reflector 522 can reflect the first split signal 583A to travel through a path leading to the dual-path interferometer 540.

[0108] The second split signal 583B can be directed through the test path 530 and ultimately to the target structure 112. The test path 530 can be at least partially included in the optical fiber 534. Along the test path 530 can include an optical circulator 531 and the optical fiber 534. In an example, the optical fiber 534 is a multi-core optical fiber comprising a MMF core and a SMF core, such as the multi-core fiber 334 of FIG. 3. The second split signal 583B can pass through the SMF core, exit from the distal end 536, and incident on the target structure 122. Along the test path 530, the second split signal 583B can be partially reflected by a partially reflective surface, such as the distal end face 536 of the optical fiber 534, thereby producing a reflected signal 585B. The transmitted portion of the second split signal 583B exits the optical fiber 534 and incidents on the target structure 122, producing a return signal 585A. By way of example and not limitation, 20-30% of the second split signal 583B may get reflected, and the rest gets transmitted through the distal end face 536 and incidents on the target structure 122. In an example, the return signal 585A can be a reflected portion of the second split signal 583B by the target structure 122. The return signal 585A and the reflected signal 585B can be directed through the optical fiber 534, such as the SMF core of a multi-core fiber, to the dual-path interferometer 540.

[0109] The dual-path interferometer 540, which is an embodiment of the interferometer 215 of FIG. 2, can combine the reference beam 583A with each of the return signal 585A and the reflected signal 585B to create respective interference patterns (e.g., interferograms). In an example, an interference pattern can be represented by two distinct reflectance peaks at different times respectively corresponding to the return signal 585A (reflection from the target) and the reflected signal 585B (reflection from the distal end face of the optical fiber). One or more interference metrics may be generated from the interference pattern. The interference metric can be proportional to the difference of travel path lengths between the signals being interfered. Based on the interference metrics, the fiber-to-target distance estimator 560 can determine a path lengthClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 difference (ALA) between the reference path 520 travelled by the reference beam 583A and the path travelled by the return signal 585A, and a path length difference (ALB) between the reference path 520 and the path travelled by the reflected signal 585B. Based on the path length differences ALA and ALB, the fiber-to-target distance estimator 560 can determine the fiber-to-target distance (X) to be a difference between ALA and ALB, that is, X = ALA - ALB.

[0110] FIG. 5B illustrates a system 500B configured to measure a fiber- to-target distance using a common-path (or single-path) interferometer 550. In contrast to the dual-path interferometer system 500 A, the common-path interferometer system 500B does not have the beam splitter 510 or the reference path 520 for transmitting the dedicated reference beam split from the beam splitter. Instead, in the system 500B can directly pass the optical or EM signal 583 through the test path 530. As similarly described above with respect to system 500A, as the optical or EM signal 583 travels through the optical fiber 534 or a fiber core therewithin (e.g., a SMF core), the optical or EM signal 583 can be partially reflected by a partially reflective surface, such as the distal end face 536 of the optical fiber 534, producing a reflected signal 595B. The transmitted portion of the optical or EM signal 583 continues to travel and incidents on the target structure 122, and produces a return signal 595A. In an example, the return signal 595A can be a portion of the optical or EM signal 583 reflected from the target structure 122. The return signal 595A and the reflected signal 595B can be directed through the optical fiber 534, such as the SMF core of a multi-core fiber, redirected by the optical circulator 531 to the common-path interferometer 550. The common-path interferometer 550, which is an embodiment of the interferometer 215 of FIG. 2, can combine the return signal 595A and the reflected signal 595B to create an interference pattern, and generate one or more interference metrics proportional to the difference of travel path lengths between the signals being interfered. In an example, an interference pattern is represented by two distinct reflectance peaks at different times respectively corresponding to the return signal 595A (reflection from the target) and the reflected signal 595B (reflection from the distal end face of the optical fiber). Based on the interference metrics, the fiber-to-target distance estimator 560 can determine the fiber-to-target distance (X) to be the path lengthClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 difference between the path travelled by the return signal 595A and the path travelled by the reflected signal 595B.

[0111] FIG. 5C illustrates a system 500C, a variation of the system 500B by including an at least partially reflective member integrated into or affixed to the optical fiber 534. An example of such at least partially reflective member is a fiber Bragg grating (FBG) 390 inscribed in a fiber core of the optical fiber 534, such as the SMF core of the multi -core optical fiber 334. Although FBG 390 may alternatively be inscribed on a different fiber core such as the MMF core, when the MMF core is used for delivering relatively high-power therapeutic laser pulses, the FBG 390 is preferably inscribed in the SMF core over the MMF core at least due to the concern that FBG may affect therapeutic laser delivery through the MMF core.

[0112] As the optical or EM signal 583 travels along the fiber core (e.g., the SMF core), a portion of signal 583 may be reflected by the FBG 390. The resulting FBG-reflected signal portion 595C can be directed to the common-path interferometer 550 via the SMF core. The transmitted portion of the optical or EM signal 583 continues to travel along the fiber core until reaching the distal end face 536, where a portion thereof gets reflected to produce a reflected signal 595B. The transmitted portion of the optical or EM signal 583 exists the distal end face 536, incidents on the target structure 122, and produces a return signal 595A. The return signal 595A and the reflected signal 595B can be directed through the optical fiber 534, such as the SMF core of a multi -core fiber, to the common-path interferometer 550.

[0113] The common-path interferometer 550 can use the FBG-reflected signal portion 595C as a reference beam, combine it with each of the return signal 595A and the reflected signal 595B to create respective interference patterns, and generate respective one or more interference metrics. Because the FBG 390 is inscribed in the fiber core (e.g., SMF core) at a pre-determined distance proximal to the distal end 536 of the optical fiber 534, the distance of the path that the FBG-reflected signal portion 595C travels (from the FBG 390 to the common-path interferometer 550, hereinafter referred as a “FBG reference path”) is also pre-determined and known for a given system setup.

[0114] Based on the interference metrics, the fiber-to-target distance estimator 560 can determine a path length difference (ALA) between the FBGClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 reference path travelled by the FBG-reflected signal portion 595C and the path travelled by the return signal 595A, and a path length difference (ALB) between the FBG reference path and the path travelled by the reflected signal 585B. Based on the path length differences ALA and ALB, the fiber-to-target distance estimator 560 can determine the fiber-to-target distance (X) to be the difference between ALA and ALB, that is, X = ALA - ALB.

[0115] Because the FBG-reflected signal portion 595C travels along the path (the “FBG reference path”) with a pre-determined known length, the FBG- reflected signal portion 595C can be used as a well-controlled reference beam in interferometry -based fiber-to-target measurement. In certain occasions during an endoscopic procedure, a user (e.g., an endoscopist) may trim a distal portion of the laser fiber. The trimmed distal end face may have a rough or irregular surface. This may reduce the quality or usability of the reflected signal 595B, such as due to high signal -to-noise ratio and / or weaker or distorted reflected signal. In contrast, the FBG 390 can be positioned at a “safe” location sufficiently away from the distal end 536 of the optical fiber, such that the FBG- reflected signal portion 595C would not be, or less likely to be, affected by fiber trimming. The FBG-reflected signal portion 595C can therefore serve as a more reliable and robust reference signal to be interfered with the return signal 595 A. An interference metric between the FBG-reflected signal portion 595C and the return signal 595A can be proportional to the path length difference (ALA) between the FBG reference path travelled by the FBG-reflected signal portion 595C and the path travelled by the return signal 595A. The location of the target structure 122 with respect to the FBG 390 (hereinafter “FBG-to-target distance”) can be determined based on the estimated path length difference (ALA). In case of fiber trimming that causes a rough or irregular fiber end surface, the FBG-to- target distance may be relied upon to produce more accurate target localization than the fiber-to-target distance measurement. The controller circuit 218 of FIG. 2 or the controller circuit 318 of FIG. 3 can determine whether or not to adjust a position or an orientation of the distal end of the optical fiber, or to adjust the laser output setting, based at least in part on the FBG-to-target distance.

[0116] FIG. 6 is a schematic diagram of an exemplary computer-based clinical decision support system (CDSS) 610 that can be configured to determine a proper laser output setting or a desired laser fiber location or orientation basedClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 on sensor data collected by the sensors or data receivers 220, or processed information from the spectrometer 213 and / or the interferometer 215 as illustrated in FIG. 2, hereinafter collectively referred to as the “input features”. In various embodiments, the CDSS 610 includes an input interface 612 through which the input features which are specific to a patient are provided to a trained ML model 614 (also referred to as an Al model). The feedback analyzer 212 (shown in FIG. 2) performs an inference operation in which the input features are applied to the ML model 614 to generate a laser output setting or to determine a desired laser fiber location or orientation as an inference output at the output interface 616. The inference output may be output to an output device 640, which may include a user interface (UI) through which the laser output setting or laser fiber location or orientation can be communicated to a user, e.g., a clinician, or to a controller device such as the feedback analyzer 212for performing a desired action.

[0117] In some embodiments, the input interface 612 may be a direct data link between the CDSS 610 and one or more feature generating devices 630 that generate at least some of the input features. For example, the input interface 612 may transmit the input features directly to the CDSS 610 during a therapeutic and / or diagnostic medical procedure. Additionally, or alternatively, the input interface 612 may be a classical user interface that facilitates interaction between a user and the CDSS 610. For example, the input interface 612 may facilitate a user interface through which the user may manually enter at least some of the input features. Additionally, or alternatively, the input interface 612 may provide the CDSS 610 with access to a database of electronic patient record 620 from which one or more input features may be extracted. In any of these cases, the input interface 612 is configured to collect sensor data in association with a specific patient on or before a time at which the CDSS 610 is used to determine a proper laser output setting or a desired laser fiber location or orientation.

[0118] The feedback analyzer 212 may perform an inference operation using the ML model 614 to generate a proper laser output setting or to determine a desired laser fiber location or orientation. For example, input interface 612 may deliver the one or more input features into an input layer of the ML model 614 which propagates these input features through the ML model 614 to anClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 output layer. The ML model 614 can provide a computer system the ability to perform tasks, without explicitly being programmed, by making inferences based on patterns found in the analysis of data. The ML model 614 explores the study and construction of algorithms (e.g., machine-learning algorithms) that may learn from existing data and make predictions about new data. Such algorithms operate by building an ML model from example training data in order to make data-driven predictions or decisions expressed as outputs or assessments, such as determining or adjusting the laser output setting 216, as stated above.

[0119] The ML model may be trained using supervised learning or unsupervised learning. Supervised learning uses prior knowledge (e.g., examples that correlate inputs to outputs or outcomes) to learn the relationships between the inputs and the outputs. The goal of supervised learning is to learn a function that, given some training data, best approximates the relationship between the training inputs and outputs so that the ML model can implement the same relationships when given inputs to generate the corresponding outputs. Unsupervised learning is the training of an ML algorithm using information that is neither classified nor labelled, and allowing the algorithm to act on that information without guidance. Unsupervised learning is useful in exploratory analysis because it can automatically identify structure in data.

[0120] Common tasks for supervised learning are classification problems and regression problems. Classification problems, also referred to as categorization problems, aim at classifying items into one of several category values. Regression algorithms aim at quantifying some items (for example, by providing a score to the value of some input). Some examples of commonly used supervised-ML algorithms are Logistic Regression (LR), Naive-Bayes, Random Forest (RF), neural networks (NN), deep neural networks (DNN), matrix factorization, and Support Vector Machines (SVM). Examples of DNN include a convolutional neural network (CNN), a recurrent neural network (RNN), a deep belief network (DBN), or a hybrid neural network comprising two or more neural network models of different types or different model configurations.Some common tasks for unsupervised learning include clustering, representation learning, and density estimation. Some examples of commonly usedClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 unsupervised learning algorithms are K-means clustering, principal component analysis, and autoencoders.

[0121] Another type of ML is federated learning (also known as collaborative learning) that trains an algorithm across multiple decentralized devices holding local data, without exchanging the data. This approach stands in contrast to traditional centralized machine-learning techniques where all the local datasets are uploaded to one server, as well as to more classical decentralized approaches which often assume that local data samples are identically distributed. Federated learning enables multiple actors to build a common, robust machine learning model without sharing data, thus allowing to address critical issues such as data privacy, data security, data access rights and access to heterogeneous data.

[0122] The training of the ML model may be performed continuously or periodically, or in near real time as additional procedure data are made available. The training process involves algorithmically adjusting one or more ML model parameters (e.g., weights or bias at any particular layer of a neural network model), until the ML model being trained satisfies a specified training convergence criterion. By way of example and not limitation, the ML model may be trained with weighted square loss (for explicit feedback) or with binary cross-entropy loss (for implicit feedback). Other training techniques, such as deep factorization machine, wide and deep learning, deep structured semantic models, or autoencoder based recommender systems, may be used. Then, during the inference operation, the patient specific input features provided to the ML model may be propagated from an input layer, through one or more hidden layers, and ultimately to an output layer that corresponds to the laser output setting or desired laser fiber location or orientation. During and / or subsequent to the inference operation, the laser output setting or desired laser fiber location or orientation may be communicated to the user via the user interface (UI) and / or automatically cause the feedback analyzer 212for performing a desired action.

[0123] FIG. 7 is a flow chart illustrating an example method 700 of measuring a fiber-to-target distance and using the same to control laser treatment of a target in a patient. The method 700 may be implement in and executed by the surgical laser system 200 as shown in FIG. 2, or the feedback-controlled endoscopic surgical laser system 300 as shown in FIG. 3. The method 700 mayClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 be used during endoscopic laser procedures, such as laser lithotripsy of renal stones, bezoars, gallstone, among other calculi structures, or laser incision or vaporization of soft tissue. Although the processes of the method 700 are drawn in one flow chart, they are not required to be performed in a particular order. In various examples, some of the processes can be performed in a different order than that illustrated herein.

[0124] At step 710, a relatively high-power therapeutic laser beam is directed to a target structure via a first fiber core of a multi -core optical fiber. The multi-core fiber, such as the multi-core optical fiber 400 as shown in FIGS. 4A-4B, includes a first fiber core (e.g., a MMF core) and a second fiber core (e.g., a SMF core). The second fiber core has a smaller diameter than the first fiber core. The first and second fiber cores may extend in parallel along a length of the multi-core optical fiber. In an example, a central longitudinal axis of the first fiber core can be offset from a central longitudinal axis of the multi-core optical fiber.

[0125] At step 720, an optical or EM signal (e.g., a non-therapeutic laser) can be directed to the target structure via the second fiber core of the multi -core fiber. The second fiber core can be optically coupled to a non-therapeutic signal source. In response to the optical or EM signal irradiating on the target structure, a return signal can be received at the distal end of the optical fiber and transmitted through the second fiber core to a feedback analyzer.

[0126] At step 730, a characteristic of the target structure can be determined based at least in part on the return signal. By way of example and not limitation, the characteristic of the target structure may include at least one of a fiber-to-target distance between a distal end of the multi-core optical fiber and the target structure, a pressure experienced by the distal end of the multi-core optical fiber, a temperature at the distal end of the multi-core optical fiber, or a location or an orientation of the distal end of the multi-core optical fiber. In an example, to determine the fiber-to-target distance, the optical or EM signal irradiating on the target is a chirped laser, also known as a frequency-swept laser with a time-varying instantaneous frequency. The chirped laser may be split into a first portion that travels through the optical fiber to the target structure, and a second portion being kept local and does not travel to the target structure. A return laser signal can be detected in response to the first portion of the chirpedClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 laser irradiating on the target. The fiber-to-target distance may be determined using a coherence metric between the chirped laser excitation and the return laser signal. The optical coherence metric is correlated to the chirped laser’s roundtrip travel time between the distal end of the optical fiber and the target structure. Fiber-to-target distance estimation based on such optical coherencebased method is described in commonly assigned U.S. Provisional Patent Application No. 63 / 580,161, entitled “LASER FIBER RANGING BASED ON OPTICAL COHERENCE TOMOGRAPHY,” which is hereby incorporated by reference in its entirety. The fiber-to-target distance measurements may be filtered to remove outliers and therefore producing a more robust estimate of fiber-to-target distance.

[0127] In some examples, as the optical or EM signal travels along the optical fiber, a portion of the signal can get reflected by an at least partially reflective surface of the optical fiber (such as a distal end face of the optical fiber), or reflected by an at least partially reflective member integrated into or affixed to the optical fiber (such as an FBG as described with respect to FIGS. 3 and 5C). One or more of the reflected signal portions can be fed into an interferometer to produce an interference pattern. A fiber-to-target distance may be determined based on one or more interference metrics derived from the interference pattern. Examples of interferometry -based methods of measuring a fiber-to-target distance using one or more reflected signal portions are described below with respect to FIG. 7.

[0128] At step 740, a decision of whether or not to adjust a position or an orientation of the distal end of the optical fiber relative to the target can be made based at least in part on the determined target characteristic, such as the fiber-to- target distance. If the determined fiber-to-target distance exceeds a threshold or is out of a specified range, a control signal may be generated to the surgical laser system to adjust the position or orientation of the distal end of the optical fiber. The adjustment may be carried out using a robotic device, such as the actuator 260 shown in FIG. 2 that can robotically advance or retract the optical fiber, or change an aiming angle of the distal end of the optical fiber with respect to the target structure. For example, if the fiber-to-target measurement exceeds a distance threshold, the optical fiber may be robotically manipulated to advance the distal end closer to the target. Adjustment of the position or the orientation ofClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 the distal end of the optical fiber may additionally or alternatively be based on target characteristics (e.g., target type or composition), which can be identified using, for example, a spectroscopic property of the target, as described above with respect to FIG. 2.

[0129] At step 750, a laser treatment may be provided to the target structure in accordance with a laser output setting when the fiber-to-target distance satisfies a condition, such as within a specific range. The laser output setting includes one or more laser output parameters such as pulse amplitude, pulse rate, power intensity, duration, frequency, pulse shape, exposure time, among other laser irradiation parameters. The laser output setting may be adjusted based on target type or composition, which can be identified based at least in part on the spectroscopic property as described above with respect to FIG. 2. Additionally or alternatively, the laser output setting may be adjusted based on the fiber-to-target distance measurement. For example, if the target structure is identified as an intended treatment target type (e.g., a particular soft tissue or calculi structure), and if the fiber-to-target distance satisfies a specific condition (e.g., falling below a distance threshold or within a specified laser firing range), then the laser pulses may be delivered to the target structure. If the target structure is not within the range of the laser, then the laser source may be temporarily “locked” such that no laser pulses are emitted to the target until the target structure is within the laser firing range. In some examples, the laser output setting, the identification of the target type or composition, and the fiber- to-target distance measurement may be presented to a user on a user interface. The user may accept, reject, or modify the laser output setting such as via a user interface before it is applied to the laser system to initiate or adjust the laser treatment to the target.

[0130] FIG. 8 is a block diagram illustrating an example of interferometry -based method 800 of measuring a fiber-to-target distance using reflections of an optical or EM signal directed to the target structure. The method 800 include steps that represent an embodiment of step 730 of method 700 as shown in FIG. 7.

[0131] At step 810, a relatively high-power therapeutic laser beam and an optical or EM signal can be directed to a target structure via an optical fiber, such as the multi -core fiber 400. The therapeutic laser beam may be directedClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 through a first fiber core and the optical or EM signal may be directed through a different second fiber core. As the optical or EM signal travels along the optical fiber, a portion of the signal can be reflected by an at least partially reflective surface of the optical fiber (such as a distal end face of the optical fiber), while the rest of the signal transmits therethrough and ultimately incidents on the target structure.

[0132] At step 820, a return signal in response to the optical or electromagnetic signal irradiating on the target structure and a portion of the optical or electromagnetic signal reflected by an at least partially reflective surface of the optical fiber may be received, and directed to an interferometer via the optical fiber (e.g., the SMF core of the multi-core fiber 400). In some examples, the optical fiber may include an at least partially reflective member integrated into or affixed to the optical fiber, such as an FBG as described with respect to FIGS. 3 and 5C. Such integrated or affied reflective member can reflect a portion of the optical or EM signal (e.g., an FBG-reflected signal), which can then be directed to the interferometer via the optical fiber.

[0133] At step 830, at least one interference metric may be generated using the signal portion reflected by the distal end face of the optical fiber and the return signal from the target structure. In the case where an FBG inscribed on a fiber core reflects a portion of the optical or EM signal, an interference metric can be derived from an inference pattern between the FBG-reflected signal and the return signal.

[0134] At step 840, a fiber-to-target distance between a distal end of the optical fiber and the target structure can be determined based at least in part on the one or more interference metrics obtained from step 830, as described above with respect to the fiber-to-target distance estimator 216 of FIG. 2 and the fiber- to-target distance estimator 560 of FIGS. 5A-5C. Such interferometry-based determination of fiber-to-target distance may be used as a basis for adjusting the position or orientation of the distal end of the optical fiber relative to the target structure, and / to for adjusting a laser output setting of laser treatment, as described above with respect to steps 740 and 750 of method 700. In certain cases where fiber trimming during a procedure would likely reduce the quality or usability of the reflected signal portion from the fiber end surface such as due to a rough or irregular fiber end surface due to trimming, an FBG-to-target distanceClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 may be relied upon to produce more accurate target localization than the fiber- to-target distance measurement. Based on the FBG-to-target distance, a decision can be made as to whether or not to adjust and how to adjust the position or orientation of the distal end of the optical fiber, or to adjust the laser output setting.

[0135] At step 850, a relatively high-power therapeutic laser beam may be delivered to the target structure when the fiber-to-target distance is within a specific range.

[0136] FIG. 9 illustrates generally a block diagram of an example machine 900 upon which any one or more of the techniques (e.g., methodologies) discussed herein may perform. Portions of this description may apply to the computing framework of various portions of surgical laser system 200 or the endoscopic surgical laser system 300.

[0137] In alternative embodiments, the machine 900 may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine 900 may operate in the capacity of a server machine, a client machine, or both in server-client network environments. In an example, the machine 900 may act as a peer machine in peer-to-peer (P2P) (or other distributed) network environment. The machine 900 may be a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile telephone, a web appliance, a network router, switch or bridge, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as cloud computing, software as a service (SaaS), other computer cluster configurations.

[0138] Examples, as described herein, may include, or may operate by, logic or a number of components, or mechanisms. Circuit sets are a collection of circuits implemented in tangible entities that include hardware (e.g., simple circuits, gates, logic, etc.). Circuit set membership may be flexible over time and underlying hardware variability. Circuit sets include members that may, alone or in combination, perform specified operations when operating. In an example,Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 hardware of the circuit set may be immutably designed to carry out a specific operation (e.g., hardwired). In an example, the hardware of the circuit set may include variably connected physical components (e.g., execution units, transistors, simple circuits, etc.) including a computer readable medium physically modified (e.g., magnetically, electrically, moveable placement of invariant massed particles, etc.) to encode instructions of the specific operation. In connecting the physical components, the underlying electrical properties of a hardware constituent are changed, for example, from an insulator to a conductor or vice versa. The instructions enable embedded hardware (e.g., the execution units or a loading mechanism) to create members of the circuit set in hardware via the variable connections to carry out portions of the specific operation when in operation. Accordingly, the computer readable medium is communicatively connected to the other components of the circuit set member when the device is operating. In an example, any of the physical components may be used in more than one member of more than one circuit set. For example, under operation, execution units may be used in a first circuit of a first circuit set at one point in time and reused by a second circuit in the first circuit set, or by a third circuit in a second circuit set at a different time.

[0139] Machine (e.g., computer system) 900 may include a hardware processor 902 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory 904 and a static memory 906, some or all of which may communicate with each other via an interlink (e.g., bus) 908. The machine 900 may further include a display unit 910 (e.g., a raster display, vector display, holographic display, etc.), an alphanumeric input device 912 (e.g., a keyboard), and a user interface (UI) navigation device 914 (e.g., a mouse). In an example, the display unit 910, input device 912 and UI navigation device 914 may be a touch screen display. The machine 900 may additionally include a storage device (e.g., drive unit) 916, a signal generation device 918 (e.g., a speaker), a network interface device 920, and one or more sensors 921, such as a global positioning system (GPS) sensor, compass, accelerometer, or other sensors. The machine 900 may include an output controller 928, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC),Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.).

[0140] The storage device 916 may include a machine readable medium 922 on which is stored one or more sets of data structures or instructions 924 (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The instructions 924 may also reside, completely or at least partially, within the main memory 904, within static memory 906, or within the hardware processor 902 during execution thereof by the machine 900. In an example, one or any combination of the hardware processor 902, the main memory 904, the static memory 906, or the storage device 916 may constitute machine readable media.

[0141] While the machine-readable medium 922 is illustrated as a single medium, the term "machine readable medium" may include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) configured to store the one or more instructions 924.

[0142] The term “machine readable medium” may include any medium that is capable of storing, encoding, or carrying instructions for execution by the machine 900 and that cause the machine 900 to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Nonlimiting machine-readable medium examples may include solid-state memories, and optical and magnetic media. In an example, a massed machine-readable medium comprises a machine-readable medium with a plurality of particles having invariant (e.g., rest) mass. Accordingly, massed machine-readable media are not transitory propagating signals. Specific examples of massed machine- readable media may include non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EPSOM)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

[0143] The instructions 924 may further be transmitted or received over a communication network 926 using a transmission medium via the network interface device 920 utilizing any one of a number of transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), userClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone networks (e.g., cellular networks), Plain Old Telephone (POTS) networks, and wireless data networks (e.g., Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards known as WiFi®, IEEE 802.16 family of standards known as WiMax®), IEEE 802.15.4 family of standards, peer-to-peer (P2P) networks, among others. In an example, the network interface device 920 may include one or more physical jacks (e.g., Ethernet, coaxial, or phonejacks) or one or more antennas to connect to the communication network 926. In an example, the network interface device 920 may include a plurality of antennas to wirelessly communicate using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) techniques. The term “transmission medium” shall be taken to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the machine 900, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

Claims

Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1What is claimed is:

1. A multi-core optical fiber, comprising: a first fiber core configured to be coupled to a surgical laser system to direct a relatively high-power therapeutic laser beam to a target structure in a patient; and a second fiber core configured to transmit a return signal from the target structure in response to a relatively low-power optical or electromagnetic signal irradiating on the target structure.

2. The multi-core optical fiber of claim 1, wherein the first fiber core includes a multi-mode fiber (MMF), the second fiber core includes a singlemode fiber (SMF), the MMF having a larger diameter than the SMF.

3. The multi-core optical fiber of claim 2, wherein the MMF has a diameter within a range of 100-500 micrometers.

4. The multi-core optical fiber of any of claims 2-3, wherein the SMF has a diameter within a range of 5-10 micrometers.

5. The multi-core optical fiber of any of claims 2-4, wherein the MMF is configured to direct the relatively high-power therapeutic laser beam to a calculi target to produce an ablation or fragmentation effect thereon.

6. The multi-core optical fiber of any of claims 1-5, wherein the first fiber core and the second fiber core are configured to extend in parallel along a length of the multi-core optical fiber.

7. The multi-core optical fiber of any of claims 1-6, wherein the first fiber core is configured to extend along a central longitudinal axis of the multi-core optical fiber.

8. The multi-core optical fiber of any of claims 1-7, wherein the multi-core optical fiber includes an outer jacket layer, and an intermediate cladding layer disposed between the first fiber core and the outer jacket layer,Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 wherein the second fiber core is disposed within the intermediate cladding layer.

9. The multi-core optical fiber of any of claims 1-8, wherein a central longitudinal axis of the first fiber core is offset from a central longitudinal axis of the multi-core optical fiber.

10. A surgical laser system, comprising: a laser system configured to generate a relatively high-power therapeutic laser beam; a multi-core optical fiber, including a first fiber core configured to be optically coupled to the laser system and to direct the relatively high-power therapeutic laser beam to a target structure in a patient, and a second fiber core configured to transmit a return signal from the target structure in response to a relatively low-power optical or electromagnetic signal irradiating on the target structure; and a controller circuit configured to determine a characteristic of the target structure based at least in part on the return signal.

11. The surgical laser system of claim 10, wherein the characteristic of the target structure comprises at least one of a fiber-to-target distance between a distal end of the multi-core optical fiber and the target structure, a pressure experienced by the distal end of the multi-core optical fiber, a temperature at the distal end of the multi-core optical fiber, an orientation of the distal end of the multi-core optical fiber, or a location of the distal end of the multi -core optical fiber.

12. The surgical laser system of any of claims 10-11, wherein the controller circuit is configured to, based at least in part on the determined characteristic of the target, generate a control signal to adjust a position or an orientation of a distal end of the multi-core optical fiber relative to the target structure, and / or to adjust a therapeutic laser output setting.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO113. The surgical laser system of any of claims 10-12, wherein the first fiber core of the multi-core optical fiber includes a multi-mode fiber (MMF), the second fiber core of the multi-core optical fiber includes a single-mode fiber (SMF), the MMF having a larger diameter than the SMF.

14. The surgical laser system of any of claims 10-13, wherein the first fiber core and the second fiber core are configured to extend in parallel along a length of the multi-core optical fiber.

15. The surgical laser system of any of claims 10-14, wherein the multi-core optical fiber includes an outer jacket layer, and an intermediate cladding layer disposed between the first fiber core and the outer jacket layer, wherein the second fiber core is disposed within the intermediate cladding layer.

16. The surgical laser system of any of claims 10-15, wherein the second fiber core is further configured to transmit the relatively low-power optical or electromagnetic signal from a non-therapeutic signal source to the target structure.

17. The surgical laser system of any of claims 10-16, wherein the relatively low-power optical or electromagnetic signal is a non-therapeutic laser beam having a lower energy than the relatively high-power therapeutic laser beam, wherein the return signal includes a return laser signal.

18. The surgical laser system of any of claims 10-17, comprising a sensor configured to sense at least one of a pressure or a temperature at the target structure, wherein the controller circuit is configured to, based at least in part on the sensed pressure and / or temperature, generate a control signal to adjust a position or an orientation of a distal end of the multi-core optical fiber relative to the target structure, and / or to adjust a therapeutic laser output setting.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO119. The surgical laser system of any of claims 10-18, wherein the controller circuit is configured to generate a control signal to a mechanism coupled to the multi-core optical fiber to automatically adjust a position or an orientation of a distal end of the multi-core optical fiber relative to the target structure based on the determined characteristic of the target structure.

20. The surgical laser system of any of claims 10-19, comprising a user interface configured to present to a user the determined characteristic and a recommendation to adjust a position or an orientation of a distal end of the multi-core optical fiber relative to the target structure.

21. The surgical laser system of any of claims 10-20, wherein a central longitudinal axis of the first fiber core is offset from a central longitudinal axis of the multi-core optical fiber.

22. A method of operating a surgical laser system during a laser procedure in a patient, the method comprising: directing a relatively high-power therapeutic energy via a first fiber core of a multi-core optical fiber to a target structure; directing a relatively low-power optical or electromagnetic signal through a second fiber core of the multi-core optical fiber to the target structure, and receiving a return signal from the target structure via the second fiber core; determining a characteristic of the target structure based at least in part on the return signal; and determining whether or not to adjust (i) a position or an orientation of a distal end of the multi-core optical fiber relative to the target structure and / or (ii) a power of the relatively high-power therapeutic energy based at least in part on the determined characteristic of the target structure.

23. A surgical laser system, comprising: a laser system configured to generate a therapeutic laser beam for treating a target structure in a patient; a non-therapeutic signal source configured to generate an optical or electromagnetic signal;Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 an optical fiber configured to direct (i) the therapeutic laser beam and (ii) the optical or electromagnetic signal to the target structure; and a controller circuit configured to: determine a fiber-to-target distance between a distal end of the optical fiber and the target structure based at least in part on (i) a portion of the optical or electromagnetic signal reflected by an at least partially reflective surface of the optical fiber, and (ii) a return signal from the target structure in response to the optical or electromagnetic signal irradiating on the target structure; and generate a control signal to the laser system to deliver the therapeutic laser beam to the target structure when the fiber-to-target distance is within a specific range.

24. The surgical laser system of claim 23, wherein the at least partially reflective surface that reflects the portion of the optical or electromagnetic signal includes a distal end face of the optical fiber.

25. The surgical laser system of any of claims 23-24, further comprising an interferometer optically coupled to the optical fiber and configured to generate an interference metric using the return signal and the portion of the optical or electromagnetic signal reflected by the at least partially reflective surface of the optical fiber, wherein the controller circuit is configured to determine the fiber-to- target distance based at least in part on the generated interference metric.

26. The surgical laser system of any of claims 23-25, further comprising an optical component inscribed in the optical fiber at a pre-determined distance from a proximate end of the optical fiber, wherein the controller circuit is further configured to determine the fiber- to-target distance based at least in part on a portion of the optical or electromagnetic signal reflected from the optical component.

27. The surgical laser system of claim 26, wherein the optical component comprises a fiber Brag grating.Client File #: GAP24082-URJD-WO1Dkt #: 5409.938WO128. The surgical laser system of any of claims 23-27, wherein the optical fiber is a multi-core optical fiber comprising (i) a first fiber core optically coupled to the laser system and configured to direct the therapeutic laser beam to the target structure, and (ii) a second fiber core optically coupled to the non- therapeutic signal source and configured to direct the optical or electromagnetic signal to the target structure.

29. The surgical laser system of claim 28, wherein the second fiber core is configured to further direct the return signal and the portion of the optical or electromagnetic signal reflected by the at least partially reflective surface of the optical fiber to an interferometer.

30. The surgical laser system of any of claims 28-29, wherein the first fiber core includes a multi-mode fiber (MMF), the second fiber core includes a singlemode fiber (SMF), the MMF having a larger diameter than the SMF.

31. The surgical laser system of any of claims 28-30, wherein a central longitudinal axis of the first fiber core is offset from a central longitudinal axis of the multi-core optical fiber.

32. The surgical laser system of any of claims 28-31, wherein the first fiber core is configured to direct the therapeutic laser beam to a calculi target to produce an ablation or fragmentation effect thereon.

33. The surgical laser system of any of claims 23-32, further comprising a beam splitter configured to optically split the optical or electromagnetic signal into first and second split signals, wherein the first split signal is directed through a first optical path having a pre-determined known length to a reflector, wherein the second split signal is directed through a second optical path to the target structure.

34. The surgical laser system of claim 33, wherein the controller circuit is configured to determine the fiber-to-target distance based at least in part on (i) aClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 first return signal from the reflector in response to the first split signal and (ii) a second return signal from the target structure in response to the second split signal.

35. The surgical laser system of any of claims 23-34, wherein the controller circuit is configured to provide the determined fiber-to-target distance to a user interface for allowing a user to adjust, based at least in part on the fiber-to-target distance, at least one of (i) a position or an orientation of the distal end of the optical fiber relative to the target structure, or (ii) a therapeutic laser output setting of the laser system.

36. The surgical laser system of any of claims 23-35, wherein the controller circuit is configured to provide the determined fiber-to-target distance to the controller circuit for automatically adjusting, based at least in part on the fiber- to-target distance, at least one of (i) a position or an orientation of the distal end of the optical fiber relative to the target structure, or (ii) a therapeutic laser output setting of the laser system.

37. A method of operating a surgical laser system during a laser procedure in a patient, the method comprising: directing a therapeutic laser beam and an optical or electromagnetic signal through an optical fiber to a target structure; in response to the optical or electromagnetic signal irradiating on the target structure, receiving (i) a portion of the optical or electromagnetic signal reflected by an at least partially reflective surface of the optical fiber and (ii) a return signal from the target structure; determining a fiber-to-target distance between a distal end of the optical fiber and the target structure based at least in part on (i) the received portion of the reflected optical or electromagnetic signal and (ii) the return signal; and delivering the therapeutic laser beam to the target structure when the fiber-to-target distance is within a specific range.

38. The method of claim 37, further comprising generating, via an interferometer optically coupled to the optical fiber, an interference metricClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 between the return signal and the portion of the optical or electromagnetic signal reflected by the at least partially reflective surface of the optical fiber, wherein determining the fiber-to-target distance is based at least in part on the generated interference metric.

39. The method of any of claims 37-38, further comprising directing the optical or electromagnetic signal to an optical component inscribed in the optical fiber at a pre-determined distance from a proximate end of the optical fiber, wherein determining the fiber-to-target distance is based at least in part on a portion of the optical or electromagnetic signal reflected from the optical component.

40. The method of any of claims 37-39, wherein directing the therapeutic laser beam is through a first fiber core of a multi-core optical fiber, the first core having a central longitudinal axis offset from a central longitudinal axis of the multi -core optical fiber, wherein directing the optical or electromagnetic signal is through a second fiber core of the multi -core optical fiber.

41. The method of claim 40, further comprising, via the second fiber core of the multi-core optical fiber, directing (i) the return signal, and (ii) the portion of the optical or electromagnetic signal reflected by the at least partially reflective surface of the optical fiber to an interferometer.

42. The method of any of claims 37-41, wherein the therapeutic laser beam includes a lithotripsy laser beam delivered to a calculi target to produce an ablation or fragmentation effect thereon.

43. The method of any of claims 37-42, further comprising: optically splitting the optical or electromagnetic signal into first and second split signals using a beam splitter; directing the first split signal through a first optical path having a predetermined known length to a reflector; andClient File #: GAP24082-URJD-WO1Dkt #: 5409.938WO1 directing the second split signal through a second optical path to the target structure.

44. The method of claim 43, wherein determining the fiber-to-target distance is based at least in part on a first return signal from the reflector in response to the first split signal and a second return signal from the target structure in response to the second split signal.

45. The method of any of claims 37-44, further comprising providing the determined fiber-to-target distance to a user interface for allowing a user to adjust, based at least in part on the fiber-to-target distance, at least one of (i) a position or an orientation of the distal end of the optical fiber relative to the target structure, or (ii) a therapeutic laser output setting of the laser system.

46. The method of any of claims 37-45, further comprising automatically adjusting, via a control mechanism and based at least in part on the fiber-to- target distance, at least one of (i) a position or an orientation of the distal end of the optical fiber relative to the target structure using a mechanism, or (ii) a therapeutic laser output setting of the laser system.

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