Directing light into an optical fiber

Abstract

The system can direct light into an optical fiber. Imaging optics can form an image of a distal end of the optical fiber. An actuatable optical element can be configured to define an optical path that extends to the actuatable optical element and further to the distal end of the optical fiber. A processor can determine a location of a specified feature in the image. Based on the location of the specified feature in the image, the processor can cause the actuatable optical element to actuate to align the optical path to a core of the optical fiber. A light source can direct a light beam along the optical path to couple into the core of the optical fiber.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 034,277, filed June 3, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to an optical system that can guide light into an optical fiber. Background Technology

[0004] Optical systems can use optical fibers, such as single-mode fibers. Misalignment of the beam relative to the core of the single-mode fiber can reduce the coupling efficiency of the beam into the core and may increase losses in the optical system. Summary of the Invention

[0005] In one example, a system can guide light into an optical fiber. The system includes imaging optics, actuable optics, a processor, and a light source. The imaging optics are configured to form an image of the end of the optical fiber. The actuable optics are configured to define an optical path extending to the actuable optics and further to the end of the optical fiber. The processor is configured to determine the location of a specified feature in the image. The processor is further configured to actuate the actuable optics based on the location of the specified feature in the image to align the optical path with the core of the optical fiber. The light source is configured to guide the light beam along the optical path to couple it into the core of the optical fiber.

[0006] In another example, a method is used in an operating system to guide light into an optical fiber. The system includes an imaging optics device, a processor, and an actuable optical element. The actuable optical element defines an optical path that extends to the actuable optical element and further to the end of the optical fiber. The method includes: generating an image of the end of the optical fiber using the imaging optics device; determining the location of specified features in the image using the processor; actuating the actuable optical element based on the location of the specified features in the image using the processor to align the optical path with the core of the optical fiber; and guiding the light beam along the optical path to couple it into the core of the optical fiber.

[0007] In another example, a computer-readable medium stores instructions that, when executed by a processor of a system for directing light into an optical fiber, can cause the processor to perform operations such as those described above or elsewhere in this specification. Attached Figure Description

[0008] Figure 1 A schematic diagram of an example apparatus including a system for guiding light into an optical fiber is shown.

[0009] Figure 2An end view of an example light source configured as a fiber bundle is shown, which is suitable for... Figure 1 The system.

[0010] Figure 3 It shows Figure 1 A top view of an example of a system where the objective lens element is configured as an objective mirror.

[0011] Figure 4 It shows the applicable Figure 1 A top view of an example of a longitudinal position sensor element of the system.

[0012] Figure 5 It shows the applicable Figure 1 A top view of another example of a longitudinal orientation sensor element of the system.

[0013] Figure 6 It shows the applicable Figure 1 A top view of another example of a longitudinal orientation sensor element of the system.

[0014] Figure 7 It shows Figure 1 A top view of the longitudinal orientation adjuster element in the system.

[0015] Figure 8 It shows the applicable Figure 1 A top view of an example of a longitudinal orientation adjuster element of the system.

[0016] Figure 9 A flowchart illustrating an example of a method for an operating system to guide light into an optical fiber is shown.

[0017] Figure 10 A flowchart illustrating an example of another method used by an operating system to guide light into an optical fiber is shown.

[0018] In all the figures, corresponding reference numerals indicate corresponding parts. Elements in the figures are not necessarily drawn to scale. The configurations shown in the figures are merely examples and should not be construed as limiting the scope of the invention in any way. Detailed Implementation

[0019] In one example, the system can guide light into an optical fiber. Imaging optics can form an image of the end of the fiber. Actuable optics can define an optical path extending to the actuable optics and further to the end of the fiber. A processor can determine the location of a specified feature in the image. Based on the location of the specified feature in the image, the processor can actuate the actuable optics to align the optical path with the core of the fiber. A light source can guide the beam along the optical path to couple it into the core of the fiber.

[0020] This system identifies features in an image at the end of an optical fiber and then actively aligns the optical path with the fiber core using the location of these features. This active alignment improves the robustness of the beam alignment with the fiber core. This improved alignment robustness helps compensate for misalignments caused by physical misalignments in the fiber, such as those due to manufacturing tolerances or non-ideals in the installation of mechanical supports. As a result, this system achieves higher beam-to-fiber core coupling efficiency compared to other similar systems that do not use this technology.

[0021] Furthermore, in various examples, active alignment can be performed once or multiple times for each use of the system. Active alignment can be performed before and / or during system use. As a specific example, performing active alignment once or multiple times during operation can help improve or maintain alignment while the optical system is running. For example, during operation, the optical system may experience movement, temperature changes, physical shocks or vibrations (such as those caused by airflow), and / or other environmental or physical changes that affect alignment. The systems described below can compensate for environmental or physical changes periodically, in response to a determination of misalignment, or in real time, and can help improve or maintain sufficiently high coupling when the optical system is used. The term "sufficiently high" is used here to indicate sufficient coupling to enable the system to operate at the performance level targeted by the system design (e.g., regarding resolution, accuracy, power consumption, etc.).

[0022] Furthermore, this system can help achieve sufficiently high coupling efficiency without direct contact with the fiber optic end. Because the system uses non-contact alignment of the optical path to the fiber, it can help reduce contamination and physical wear at the fiber optic end.

[0023] Examples of optical systems that can incorporate one or more features from the systems described below include fiber-optic strain, temperature, or shape sensing systems. As a specific example, an optical system couples light into a multi-core fiber to sense the three-dimensional orientation of an element in space in real-time or near real-time. As another specific example, an optical system couples light into a multi-core fiber to sense the three-dimensional shape of the fiber in real-time or near real-time.

[0024] Furthermore, examples of optical systems can include medical or non-medical systems. Examples of medical systems can include systems used for diagnosis or treatment, including surgical systems. In the medical system examples, the system described below can be located in the optical path between one or more light sources and one or more cores of the sensing fiber to help establish and / or maintain a sufficiently high coupling efficiency (or multiple coupling efficiencies) for light entering the sensing fiber during one or more medical procedures. This is merely an example of the uses of the system described in detail below. Other uses are also possible.

[0025] Figure 1A schematic diagram of an example of a device 1 including a system 100 for guiding light into an optical fiber is shown. Because the system 100 can identify features in an image of the end of the optical fiber and then actively align the optical path with the core of the optical fiber using the location of the features, the system can achieve relatively robust alignment of the beam to the core of the optical fiber.

[0026] Controller 10 may include various optical and electronic components. For medical applications, controller 10 may be configured as a single unit that can be used and reused in multiple procedures. For applications involving shape sensing, such as sensing the three-dimensional orientation or shape of an optical fiber, controller 10 may include interrogator 12. Interrogator 12 may guide light into the optical fiber and analyze the light returning from the fiber. Interrogator 12 may use techniques such as optical frequency domain reflectometry (OFDR) to determine the three-dimensional orientation of the optical fiber.

[0027] In some examples, a portion of the equipment may be configured as a replaceable element that can be used for one or more procedures, or for all of one or more procedures, and then discarded. The replaceable element may include catheter 14, which may include a sensing fiber 16 extending along at least a portion of the length of catheter 14. In medical examples, catheter 14 and sensing fiber 16 may be maintained or reprocessed in a clean environment or in a sterile environment (if clinically necessary) prior to use.

[0028] The system 100, described in detail below, can use active alignment to optically connect the fiber 16 to the controller 10. When optically connected, the interrogator 12 can direct light into the sensing fiber 16 (via system 100), receive light reflected from locations along the length of the sensing fiber 16 (also reflected by system 100), and analyze the reflected light (e.g., via OFDR) to determine strain, temperature, or other physical information of the sensing fiber 16. For shape sensing applications, the interrogator 12 is configured to determine the three-dimensional orientation or shape of the sensing fiber 16. For clarity, in the following discussion, the sensing fiber 16 will be referred to as fiber 108. It should be understood that fiber 108 may include the sensing fiber 16, or may optionally include a separate portion of an optical fiber coupled to the proximal end of the sensing fiber 16. References to fiber 108 below may include one or both of these.

[0029] Controller 10 may include fiber optic connectors 18, such as multi-core fibers or multiple single-mode fibers, which can provide light as input to system 100. In this document, multiple single-mode fibers may also be referred to as a single-mode fiber bundle or fiber bundle, although multiple single-mode fibers may be bundled together, arranged in a linear array, etc. System 100 can guide the light provided by the fiber optic connectors 18 through various elements in system 100 to couple into sensing fiber 16. Light reflected from a location along the length of sensing fiber 16 can return to system 100, can propagate through various elements in system 100, can propagate through fiber optic connectors 18, and can be processed by interrogator 12 in controller 10. System 100 can guide a portion of the light through various elements to one or more detectors. One or more detectors can generate one or more control signals. System 100 can use one or more control signals to control one or more actuated elements in system 100 to improve the coupling efficiency of light entering fiber 108.

[0030] The controller 10 may include an electrical connector 20 that can provide power to the system 100. A processor 114, which may be located in the controller 10 or in the system 100, may receive control signals from one or more detectors in the system 100 and may drive one or more actuable elements in the system 100 to improve coupling efficiency.

[0031] During operation, the imaging optics in system 100 can form an image 104 of the end 106 of fiber 108. Actuable optical elements 110 (such as pivotable mirrors) can define an optical path 112 extending to the actuable optical elements 110 and, when fiber 108 is present, further extending to the end 106 of fiber 108. Processor 114 can determine the location of specified features (such as the circumferential edge of the end 106 of fiber 108) in image 104. Although processor 114 is shown positioned with system 100, it will be understood that processor 114 can alternatively be positioned with controller 10. Based on the location of the specified features in image 104, processor 114 can actuate the actuable optical elements 110 to align the optical path 112 with the core 116 of fiber 108.

[0032] Optical path 112 is the geometry extending from the optical element between fiber connector 18 and optical fiber 108. Specifically, one end of the optical path is located at fiber connector 18, and the other end is located at optical fiber 108 when optical fiber 108 is present. During operation of system 100, the optical element can be bent, translated, rotated, and otherwise aligned with optical path 112. During operation of system 100, beam 120 is guided along optical path 112 from the optical element to the optical element, such that beam 120 follows optical path 112. It is advantageous to clarify that optical path 112 can be redirected whether beam 120 is present or absent. For a configuration where optical fiber 108 includes multiple cores, system 100 can include multiple optical paths 112 propagating toward the respective cores of optical fiber 108.

[0033] Light source 118 can guide light beam 120 along optical path 112 to couple into core 116 of optical fiber 108. In some examples, controller 10 may include one or more light-emitting elements (such as light-emitting diodes or laser diodes) and one or more optical coupling elements (such as lenses) that can guide light from the light-emitting elements into one or more cores of one or more optical fibers in fiber optic connector 18. Figure 1 In this configuration, the light source 118 may include the distal end of the fiber optic connector 18 or a length of optical fiber coupled to the distal end of the fiber optic connector 18. For clarity, in the following discussion, the optical fiber in the fiber optic connector 18 will be referred to as source fiber 138. It will be understood that source fiber 138 may be the same as fiber optic connector 18, or may optionally include a separate portion of the optical fiber coupled to the distal end of the fiber optic connector 18.

[0034] For the example where fiber 108 includes a single core 116, source fiber 138 may include a single core 140. For the example where fiber 108 includes multiple cores 116, source fiber 138 may also include multiple cores 140. The multiple cores 140 may be arranged in a pattern similar to the pattern of multiple cores in fiber 108. As a specific example, source fiber 138 and fiber 108 may each include six cores positioned in a hexagonal pattern, the hexagons surrounding the center of the circumferential edge of the fiber. During operation, system 100 may simultaneously direct light from the multiple cores 140 of source fiber 138 into the multiple cores of fiber 108.

[0035] For the example of fiber 108 including multiple cores 116, an alternative to receiving light from multiple cores of a multi-core fiber in fiber optic connector 18 is to receive light from the cores of multiple single-core fibers (such as fibers in a fiber bundle or fiber linear array). In some examples, fiber 108 may be a multi-core fiber. The core 116 of fiber 108 may be the first core of a multiple core of a multi-core fiber. Optical path 112 may be the first optical path of a plurality of optical paths defined by actuable optical element 110. Each of the plurality of optical paths may extend to actuable optical element 110 and may further extend to the end 106 of the multi-core fiber. Processor 114 may actuate actuable optical element 110 to align optical path 112 with core 116 by actuating actuable optical element 110 to simultaneously align multiple optical paths with multiple cores of the multi-core fiber. Light source 118 may be the first light source of a plurality of light sources. Each of the plurality of light sources may guide a corresponding beam along a corresponding optical path in the plurality of optical paths to couple to a corresponding core of the plurality of cores of the multi-core fiber.

[0036] Figure 2 An end view is shown of an example of a light source 118 configured as a fiber bundle 200, which is suitable for use with... Figure 1 System 100. Fiber bundle 200 includes multiple single-mode fibers 202, 204, 206, 208, 210, and 212. These multiple single-mode fibers each include corresponding cores 216, 218, 220, 222, 224, and 226. The multiple single-mode fibers surround a central fiber 214 having a core 228. In this example, the multiple single-mode fibers 202, 204, 206, 208, 210, and 212 are arranged in a regular hexagonal pattern around the central fiber 214. Fiber bundle 200 is suitable for use as a light source 118 for fiber 108, which has multiple cores arranged in a similar hexagonal pattern. Figure 2 The fiber bundle 200 is just one example of a fiber bundle; other arrangements of fibers are possible. System 100 may further include amplifying optics that can provide magnification to multiple optical paths. The magnification may be equal to or (within tolerances, such as 1%, 5%, 10%, or 20%) substantially equal to the ratio of the spacing between adjacent cores of the multi-core fiber to the spacing between adjacent cores of the multiple single-core fibers. The amplifying optics may include a source objective element 148 (described in detail below) and an objective element 122 (also described in detail below), the source objective element 148 collimating light emitted from the light source 118 to form a beam 120, and the objective element 122 focusing the beam 120 to couple into the fiber 108. The ratio of the focal lengths of the source objective element 148 and the objective element 122 may be selected to be equal to or substantially equal to the ratio of the spacing between adjacent cores of the multi-core fiber of fiber 108 to the spacing between adjacent cores of the multiple single-core fibers of the light source 118.

[0037] Back Figure 1 In some examples, processor 114 can actuate actuable optics 110 to align optical path 112 with core 116 by using at least the following two operations: First, processor 114 can determine the offset between the position of a specified feature in image 104 and a predetermined target position in image 104. Second, processor 114 can actuate actuable optics 110 to reduce the offset. Processor 114 may optionally repeat these two operations during operation of system 100 to help maintain sufficiently high coupling efficiency to core 116 during operation. For example, processor 114 can determine the pixel position (e.g., a set of orthogonal position coordinates, such as x and y) of a specified feature (such as the center of the perimeter of fiber optic 108) in image 104, compare the determined pixel position with a specified pixel position corresponding to a well-aligned fiber optic 108 (e.g., a set of values ​​such as stored in a lookup table or other suitable memory), and actuate actuable optics 110 to move the determined pixel position to align with the specified pixel position.

[0038] In some examples, the specified feature may include part or all of the circumferential edge of the end 106 of the fiber 108. Core 116 may be located at a predetermined core position relative to the circumferential edge of the fiber 108. The processor 114 may actuate the actuable optics 110 to align the optical path 112 with the core 116 by aligning the optical path 112 with the predetermined core position. For example, in a configuration where the fiber 108 is a single-core fiber, core 116 may be located at the center of the circumferential edge of the fiber 108. In a configuration where the fiber 108 is a multi-core fiber (e.g., a fiber with a single cladding surrounding multiple cores spaced apart from each other), core 116 may be located at a specified position relative to the circumferential edge of the fiber 108. For example, the fiber 108 may include four cores, with the central core located at the center of the circumferential edge and three cores located at the corners of an equilateral triangle centered on the central core. As another example, fiber 108 may include six cores positioned in a hexagonal pattern, the hexagonal pattern surrounding the center of the circumferential edge of fiber 108 (e.g., these cores may be located at the corners of a regular hexagon by being spaced 60 degrees, approximately 60 degrees, or within a tolerance of 60 degrees, one, two, five, or another suitable value in azimuth). As yet another example, fiber 108 may include seven cores, with the central core located at the center of the circumferential edge and six cores located at the corners of a regular hexagon centered on the central core. Other suitable multi-core configurations may also be used.

[0039] For a configuration where fiber 108 includes multiple cores, the perimeter of fiber 108 may include optional azimuth positioning features, such as partially flat edges, notches, protrusions, or other features that can mechanically or optically indicate the azimuth position of the cores. For example, fiber 108 may include a bar (not a core) extending along the length of fiber 108. Such a bar may appear as a bright spot (e.g., brighter than the area surrounding the spot) or a dark spot (e.g., darker than the area surrounding the spot) in image 104 of the end 106 of fiber 108. In some examples, the azimuth positioning features may be mechanical features of the connecting elements. For example, fiber 108 may be held in a ferrule and a standard optical connector. When manufacturing the connector, specific cores of fiber 108 may be illuminated to align specific cores with the keys of a standard fiber optic connector.

[0040] Other specified features may also be used to attach to or replace the circumferential edge of the end 106 of the fiber 108. For example, this feature may include the appearance of the core 116 of the fiber 108 in image 104. In some lighting configurations, the core 116 may appear as a dark spot in image 104, which may appear darker than the area surrounding the core 116 (e.g., with lower intensity or brightness). In other lighting configurations, the core 116 may appear as a bright spot in image 104, which may appear brighter than the area surrounding the core 116 (e.g., with higher intensity or brightness). Identifying the core 116 directly from bright and / or dark spots in an image can also be used with multi-core fibers having multiple cores.

[0041] System 100 may optionally further include an illumination source 130. Illumination source 130 may illuminate optical fiber 108 with illumination 132. Illumination 132 may have a wavelength different from that of the light beam 120. As a specific example, the wavelength of the light may be 1550 nm, and the wavelength of illumination 132 may be in the visible spectrum, such as between 400 nm and 700 nm. Other wavelength values ​​may also be used.

[0042] For a configuration including illumination source 130, at least some of the illumination 132 can be reflected or scattered from optical fiber 108 to form first light. In some examples, illumination 132 reflected from end 106 of optical fiber 108 can generate first light. In some examples, illumination entering one side of optical fiber 108 and exiting end 106 of optical fiber 108 can form first light.

[0043] Objective lens element 122 can collimate at least some of the first light to form a second light. In some examples, such as Figure 1 In this configuration, objective element 122 may include an objective lens. Optical path 112 may extend through the objective lens. Alternatively, objective element 122 may include an objective mirror. Figure 3 It shows Figure 1 This is a top view of an example of a portion of system 100, wherein objective element 122 is configured as objective mirror 302. Objective mirror 302 may have a cross-section including parabolic segments. Other configurations of objective element 122 are also possible, including multiple mirrors, multiple lenses, or a combination of at least one mirror and at least one lens. Similarly, focusing element 126 may include at least one of a focusing lens or a focusing mirror.

[0044] Back Figure 1 The dichroic mirror 124 can guide at least some of the second light away from the optical path 112 to form a third light. For example, the dichroic mirror 124 can transmit light including light in a transmission band of 1550 nm. The dichroic mirror 124 can reflect light in a reflection band including the wavelength of illumination 132, such as light in the visible spectrum. This is just a numerical example; other wavelengths and wavelength ranges can also be used.

[0045] exist Figure 1 In this configuration, dichroic mirror 124 is a long-pass dichroic mirror that transmits relatively long wavelengths (such as wavelengths used for shape sensing, optionally in the infrared portion of the electromagnetic spectrum, such as 1550 nm) and reflects relatively short wavelengths (such as wavelengths used for imaging, optionally in the visible portion of the electromagnetic spectrum, such as between 400 nm and 700 nm). Alternatively, dichroic mirror 124 can be a short-pass dichroic mirror that transmits relatively short wavelengths (such as wavelengths used for imaging) and reflects relatively long wavelengths (such as wavelengths used for shape sensing). Replacing the long-pass filter with a short-pass dichroic mirror would involve swapping the transmission arm and the reflection arm, such that the optical path 112 would be reflected at dichroic mirror 124, instead of as... Figure 1 The current transmission passes through dichroic mirror 124.

[0046] Focusing element 126 can focus the third light to form image 104 at the focal plane of focusing element 126. Imaging array 128 can be located at the focal plane of focusing element 126 and can sense image 104. In some examples, the imaging optics may include objective lens element 122, dichroic mirror 124, focusing element 126, and imaging array 128. Processor 114 can receive analog and / or digital signals corresponding to image 104 from imaging array 128. Other suitable configurations may also be used.

[0047] exist Figure 1 In the example, the actuable optical element 110 is configured as a pivotable mirror. A pivotable mirror can include a single mirror that can pivot in two dimensions, two separate mirrors each pivotable in a single dimension, multiple mirrors each pivotable in a single or two dimensions, and other suitable configurations. Figure 1 In the configuration, the pivotable mirror may include a reflector that can pivot about a pivot point, and a linear actuator 136 that can pivot the reflector about the pivot point. Although Figure 1 The pivotable mirror shown pivots only in one dimension, but it will be understood that the pivotable mirror can pivot in two orthogonal dimensions using a pair of linear actuators 136. Processor 114 can control the linear actuators 136. Processor 114 can actuate the actuable optics 110 to align the optical path 112 with the core 116 of the fiber optic 108 by pivoting the pivotable mirror based on the position of specified features in image 104 to manipulate the optical path 112.

[0048] Optical path 112 may include a fixed portion extending between light source 118 and actuable optical element 110. Optical path 112 may include a movable portion extending between actuable optical element 110 and end 106 of optical fiber 108. During operation of system 100, the movable portion of optical path 112 may move in space, while the fixed portion of optical path 112 may remain stationary. Figure 1 In this configuration, the dichroic mirror 124, the focusing element 126, and the imaging array 128 are located in the fixed portion of the optical path 112. Other configurations can also be used.

[0049] In some examples, the actuable optical element 110 can be located in the optical path 112 as telecentric. For a telecentric configuration, a pivotable mirror can produce a lateral translation of the optical path 112 at the end 106 of the fiber 108 without producing an angular change in the optical path 122 at the end 106 of the fiber 108. In some examples, positioning the pivotable mirror at the back focal plane (or rear focal plane) of the objective element 122 can produce a telecentric condition.

[0050] Figure 1 The pivotable mirror is just one example of a suitable actuable optical element 110. Other suitable configurations may include translational optical elements, such as translational lenses or translational mirrors. In some examples, translational optical elements may include objective lens element 122, system 100, and / or fiber optic cable 108.

[0051] In some examples, system 100 may include features that allow system 100 to operate in a separate environment, such as a cleanroom environment in an industrial example, or a sterile environment in a medical example involving sterility. For example, in some applications performing medical procedures, such as when system 100 may be reusable (e.g., may be capital equipment) and fiber optic cable 108 may be replaceable (e.g., may be disposed of after a single use, or after multiple uses and disposal, or after an indeterminate number of uses), system 100 may optionally include barriers, such as windows or optical surfaces. In medical examples, barriers may meet cleaning requirements to help provide a clean environment for specific medical procedures that do not require sterility, or they may meet sterility requirements to help ensure the sterility of medical procedures that do require sterility.

[0052] A window or optical surface can transmit the light beam 120 to the optical fiber 108 and can receive light from the optical fiber 108 without contacting it. In some examples, the window or optical surface can be easily cleaned between uses of the system 100 to avoid contaminating the optical fiber used in subsequent procedures. In some examples, the objective element 122 (such as an objective lens) can form part of a barrier of the system 100. For example, the objective lens can be plano-convex, where the planar side optionally forms part of a sterile barrier. Other configurations may also be used. As mentioned above, in some examples, the barrier formed by the system 100 may not be a sterile barrier because it does not meet sterility requirements.

[0053] System 100 may optionally include a field alignment lens 134 located in the optical path 112 near the end 106 of optical fiber 108. Such a field alignment lens can improve coupling efficiency when optical fiber 108 is positioned away from the central axis of the optical elements of system 100 (e.g., off-axis performance). Field alignment lens 134 may optionally have the same focal length as objective lens element 122. Field alignment lens 134 may optionally have a smaller diameter (e.g., light aperture) than the diameter of objective lens element 122. Field alignment lens 134 may optionally have a smaller numerical aperture (e.g., half the diameter divided by the focal length) than the numerical aperture of objective lens element 122. Field alignment lens 134 may optionally be configured as a plano-convex lens. Field alignment lens 134 may optionally have a planar side forming part of a sterile barrier of system 100. Because the field alignment lens 134 can be a relatively inexpensive item, it can be optionally configured as a replaceable (e.g., disposable or reusable) element that can be removed, reprocessed, reused, and / or disposed of. Such a replaceable element can optionally be packaged together with or separately from the fiber 108.

[0054] In some examples, system 100 may optionally monitor the amount of light reflected from one or more cores of optical fiber 108. For example, in orientation sensing applications, system 100 may couple light into one or more cores of optical fiber 108, where light may be reflected in varying amounts from locations along the length of optical fiber 108, and system 100 may analyze the reflected light, such as by optical frequency domain reflectometry (OFDR) performed by interrogator 12, to determine the three-dimensional orientation of optical fiber 108. In some examples, the analysis of the reflected light may include sensing the amplitude or oscillation of the reflected light. Such sensed amplitude or oscillation may correspond to the coupling efficiency of light entering optical fiber 108. System 100 may actuate actuable optics 110 to enhance, maximize, and / or optimize the sensed amplitude or oscillation of the reflected light from optical fiber 108. In some examples, system 100 may use sensed amplitude or oscillation consistent with the imaging techniques described above. For example, system 100 may use imaging techniques to perform initial positioning of optical path 112 near or at core 116 (e.g., as a coarse alignment procedure), and may use sensed amplitude or oscillation to position optical path 112 more precisely relative to core 116 (e.g., as a fine alignment procedure). In some examples, system 100 may use sensed amplitude or oscillation to position optical path 112 relative to core 116 without using the imaging techniques described above.

[0055] As described above, system 100 can illuminate fiber 108 to capture an image 104 of the end 106 of fiber 108. For a configuration where the light source 118 includes source fiber 138, system 100 can optionally illuminate the end of source fiber 138 and include additional optics to overlay a view of the end 142 of source fiber 138 onto a view of the end 106 of fiber 108 in image 104. (As an alternative to illuminating the end 142 of source fiber 138, or in addition to performing such illumination, controller 10 can inject illumination into the opposite end of source fiber 138, which can propagate along source fiber 138 to exit from the end 142 of source fiber 138. Because the illumination used for imaging can use a different wavelength than the light used for shape sensing, the injection of illumination can be performed via wavelength division multiplexing at controller 10.) Allowing simultaneous observation of the ends of both fibers can provide additional information during the assembly and alignment phases of system 100.

[0056] As described above, a first illumination source (such as 130) can illuminate fiber 108 with a first illumination (such as 132). The first illumination 132 can have a first wavelength different from the wavelength of beam 120. At least some of the first illuminations 132 can be reflected or scattered from fiber 108 to form first light. Objective lens elements 122 (such as objective lenses or objective mirrors) can collimate at least some of the first light to form second light. A second illumination source 144 can illuminate source fiber 138 with a second illumination 146. The second illumination 148 can have a second wavelength different from the first wavelength and different from the wavelength of beam 120. At least some of the second illuminations 146 can be reflected or scattered from source fiber 138 to form third light. Source objective lens elements 148 (such as source objective lenses or source objective mirrors) can collimate at least some of the third light to form fourth light. A dichroic mirror (such as 124) and a reflector 150 (such as a back reflector or back reflector prism) can superimpose the second and fourth light to form a fifth light. Figure 1 In the illustrated configuration, dichroic mirror 124 can reflect at least some of the fourth light toward reflector 150. Alternatively, dichroic mirror 124 can be oriented to reflect at least some of the second light toward reflector 150. A focusing element (such as 126) can focus the fifth light to form image 104 at the focal plane of focusing element 126. An imaging array (such as 128) located at the focal plane of focusing element 126 can sense image 104. Because the ends 106, 142 of the optical fibers can be imaged with light of different wavelengths, processor 114 can optionally separate information from the two superimposed views as needed. The superimposed views forming the ends 106, 142 of the optical fibers can provide additional information during the assembly and / or alignment phases of system 100 and / or during use of system 100. For example, since the ends of the optical fibers are visible in image 104, image 104 can be used to inspect for contamination or damage to the ends of the optical fibers.

[0057] Optical path 112 may include an optional first pivotable element 152, which can redirect optical path 112 within an angular range extending in one or two dimensions. The first pivotable element 152 may include a mirror on an adjustable mount that can controllably pivot about one, two, three, or more axes. In the case of a pivotable element pivoting about multiple axes, these axes may intersect or not intersect, or be orthogonal to each other, or be rotated off by some other angle. The phrase "pivotable element" is intended to include various "tilt / slide elements," such as elements (like mirrors) mounted on a tilt / slide stage. Although other configurations may also be used, a tilt / slide stage is generally pivotable about each of two orthogonal and intersecting axes. Figure 1In this configuration, the first pivotable element 152 may have a nominal angle of incidence of 45 degrees or about 45 degrees, such that the optical path 112 may be nominally redirected by 90 degrees or about 90 degrees. A 45-degree angle of incidence is merely one example; other suitable angles of incidence may also be used. The first pivotable element 152 may provide additional degrees of freedom during the assembly and alignment phases of the system 100. For example, positioning the first pivotable element 152 in the optical path 112 may help relax some placement tolerances on the source fiber 138 and may help compensate for rotation and / or displacement of other optical elements in the optical path 112. The first pivotable element 152 may be located in the optical path 112 between the light source 118 and the dichroic mirror 124, between the dichroic mirror 124 and the actuated optical element 110, between the actuated optical element 110 and the fiber 108, or at any other suitable location along the optical path 112.

[0058] Optical path 112 may include an optional second pivotable element 154, which can redirect optical path 112 within an angular range extending in one or two dimensions. The second pivotable element 154 may be structurally and functionally similar to the first pivotable element 152. The second pivotable element 154 may be located in optical path 112 between light source 118 and dichroic mirror 124, between dichroic mirror 124 and actuated optical element 110, between actuated optical element 110 and optical fiber 108, or at any other suitable location along optical path 112. The first pivotable element 152 and the second pivotable element 154 may be located at different locations along optical path 112 (e.g., they may be separated along the longitudinal direction of optical path 12). Although the second pivotable element 154 is... Figure 1 The image shows a second pivotable element 154 adjacent to the first pivotable element 152, with no intermediate optical elements between them. However, the second pivotable element 154 can be located at any suitable position along the optical path 112, including between beam splitters or between a beam splitter and actuable optical element 110. Using two pivotable elements separated along the optical path 112 can be helpful during the assembly and alignment of optical components in system 100. For example, using two longitudinally separated pivotable elements can allow the optical path 112 to be laterally translated (e.g., moved without rotation) to a desired position, or rotated in two dimensions while maintaining a fixed spatial position. As a specific example, using two pivotable elements can allow the optical path 112 to pass through the center of the lens rather than the edge of the lens, thereby improving the optical performance of the lens.

[0059] In some examples, it may be advantageous to use one or more pivotable elements to manipulate optical path 112 so that fiber 108 and source fiber 138 can be approximately parallel to each other (at least within a few degrees). Orienting the fibers to approximately parallel generally aligns with the use of typical physical contact connectors, which typically require insertion of the fibers from opposite sides. Modifications can be made by removing one of the pivotable elements 152 or 154, adding additional pivotable elements, modifying dichroic mirror 124 to a short-pass filter instead of a long-pass filter, and other geometric modifications. Figure 1 The configuration is set up to achieve similar conditions.

[0060] So far, the discussion has focused on the lateral alignment of optical path 112 with the core 116 of optical fiber 108. Specifically, for the coordinate system (x, y, z) at the end 106 of optical fiber 108, where z corresponds to the central axis of optical path 112, the above discussion pertains to aligning optical path 112 in the x and y dimensions. For example, an image 104 capturing the end 106 of optical fiber 108 can provide the x and y coordinates of one or more features on optical fiber 108, and system 100 can actively align optical path 112 in the x and y dimensions relative to one or more features in image 104.

[0061] In some applications, active alignment in the x and y dimensions may be sufficient to achieve sufficiently high coupling in the fiber 108. These applications can rely on the mechanical placement of the end 106 of the fiber 108, as it is accurate enough to achieve sufficiently high coupling. For example, the fiber 108 can be fitted into a fixture that positions the end 106 of the fiber 108 within a specified tolerance in a specified plane (in the z direction), such that the coupling efficiency is sufficiently high for any z-position within the tolerance.

[0062] In other applications, mechanical placement in the z-direction may not be accurate enough to achieve sufficiently high coupling. For these applications, system 100 may further include one or more longitudinal orientation sensor elements. The longitudinal orientation sensor elements can detect the longitudinal distance (e.g., a distance measured along optical path 112) between the focal point of beam 120 and the end 106 of optical fiber 108. The longitudinal orientation sensor elements can be located at any suitable position within a fixed portion of optical path 112.

[0063] Similarly, system 100 may further include one or more longitudinal azimuth adjuster elements. The one or more longitudinal azimuth adjuster elements can longitudinally position the focal point of beam 120 to reduce the longitudinal spacing between the focal point and 106 of fiber 108. The one or more longitudinal azimuth adjuster elements can be located at any suitable position within a fixed portion of optical path 112. In some examples, the one or more longitudinal azimuth adjuster elements can be located in optical path 112 between the longitudinal azimuth sensor element and fiber 108.

[0064] exist Figure 1 In this configuration, the longitudinal orientation sensor element may include a beam splitter 156, such as a dichroic beam splitter, a 50-50 beam splitter, or other suitable beam splitting element. Figure 1 In this configuration, beam splitter 156 can be positioned between dichroic mirror 124 and fiber 108 along optical path 112. Alternatively, dichroic mirror 124 can be positioned between beam splitter 156 and fiber 108 along optical path 112. Other configurations can also be used, including those that allow for the interchange of transmission and reflection paths through beam splitter 156.

[0065] Beam splitter 156 can receive light that has been reflected and / or scattered from the end 106 of optical fiber 108. Beam splitter 156 can direct a portion of the reflected light toward biprism 158, lens 160, and sensor 162. Lens 160 can focus the light emitted from biprism 158 to form an image 164 at sensor 162. Sensor 162 can be coupled to processor 114.

[0066] The biprism 158 can impart a wedge angle between the opposing halves of the reflected light, such that a specified feature in image 164 (such as the circumferential edge of fiber 108) has a corresponding replicated feature on image 164. The processor 114 can also determine the longitudinal spacing between the focal point and the end 106 of fiber 108, at least in part, based on the spacing between the specified feature and the corresponding replicated feature. For these configurations, this spacing can be considered a focal error signal. This spacing can be compared to a specified distance, which can be determined in the initial configuration of system 100, such as during initial assembly and alignment of system 100 at the factory. If the spacing is less than the specified distance, the focal point may be on one side of the end 106 of fiber 108, such as the outside of fiber 108. If the spacing is greater than the specified distance, the focal point may be on the other side of the end 106 of fiber 108, such as the inside of fiber 108.

[0067] Figure 1 The dual-prism configuration is just one example of the configuration of the longitudinal orientation sensor element. Other suitable configurations include... Figures 4-6 As shown, and described below.

[0068] Figure 4 It shows the applicable Figure 1 A top view of an example longitudinal orientation sensor element of system 100. Beam splitter 156 in optical path 112 will connect the optical fiber 108 (… Figure 1 The end of 106 () Figure 1The light portion 402 of the reflected and / or scattered beam 120 is guided toward the split-field dichroic filter 404, lens 406, and sensor 410. The first half 404A of the split-field dichroic filter 404 may have a first spectral profile (e.g., it can pass through a first wavelength or a first band). The second half 404B of the split-field dichroic filter 404 may have a second spectral profile different from the first spectral profile (e.g., it can pass through a second wavelength different from the first wavelength or a second band different from the first band). The light portion 402 can form an image 408 at the sensor 410. The sensor 410 may be coupled to the processor 114.

[0069] The light portion 402 may have multiple wavelengths. The split-field dichroic filter 404 may be configured such that a specified feature in image 408 has a corresponding replicated feature in image 408 at different wavelengths. The processor 114 may also determine the longitudinal spacing between the focal point and the end 106 of the fiber optic cable 108 based at least in part on the spacing between the specified feature and the corresponding replicated feature. As described above, this spacing can be compared with a specified distance.

[0070] Figure 5 It shows the applicable Figure 1 A top view of another example of the longitudinal orientation sensor element of system 100. The beam splitter 156 in optical path 112 will connect the optical fiber 108 (…). Figure 1 The end of 106 () Figure 1 The light portion 502 of the reflected and / or scattered light beam 120 is guided toward the liquid crystal on silicon (LCOS) device 504 with a programmable aperture, the lens 506, and the sensor 510. The light portion 502 can form an image 508 at the sensor 510. The sensor 510 can be coupled to the processor 114.

[0071] The LCOS device 504 can be implemented using time multiplexing. Figure 1 and Figure 4The illustrated components achieve a similar splitting effect. At a first time, the first half 504A of the aperture of the LCOS device 514 can be reflective, while the second half 506B of the aperture of the LCOS device 524 can be non-reflective. During this first time, the processor 114 can acquire a first image from the sensor 510. At a second time following the first time, the first half 504A of the aperture of the LCOS device 504 can be non-reflective, while the second half 504B of the aperture of the LCOS device 504 can be reflective. During this second time, the processor 114 can acquire a second image from the sensor 510. The LCOS device 504 can be configured such that a specified feature in the first image has a corresponding replicated feature in the second image. The processor 114 can also determine the longitudinal spacing between the focal point and the end 106 of the fiber optic 108 based at least in part on the spacing between the specified feature and the corresponding replicated feature. As explained above, this spacing can be compared to a specified distance.

[0072] Figure 6 It shows the applicable Figure 1 A top view of another example of the longitudinal orientation sensor element of system 100. The beam splitter 156 in optical path 112 will connect the optical fiber 108 (…). Figure 1 The end of 106 () Figure 1 The light portion 602 of the reflected and / or scattered light beam 120 is guided toward the chromatic aberration lens 606 and the sensor 610. The light portion 602 can form an image 608 at the sensor 610. The sensor 610 can be coupled to the processor 114.

[0073] The light portion 602 can have multiple wavelengths. Because the chromatic aberration lens 606 includes chromatic aberration, it can bring light of one wavelength to a first focal point at a first focal plane and bring light of a second wavelength (different from the first wavelength) to a second focal point at a second focal plane separate from the first focal plane. Note that this is typically the case for most well-designed lenses that operate at more than one wavelength in the absence of chromatic aberration, where the first and second focal planes usually coincide or nearly coincide.

[0074] A chromatic aberration lens 606 can be configured such that a specified feature in image 608 has a corresponding replicated feature in image 608 at different wavelengths. Processor 114 can further determine the longitudinal spacing between the focal point and the end 106 of fiber optic 108, at least in part, based on the size of the specified feature in image 608 and the size of the corresponding replicated feature in image 608. Alternatively, processor 114 can process image 608, such as by performing a two-dimensional fast Fourier transform on image 608, to evaluate the sharpness of image 608 at different wavelengths. The sharpness at different wavelengths can help determine the longitudinal spacing between the focal point and the end 106 of fiber optic 108, and / or can help determine at least the sign (e.g., positive or negative) of the longitudinal spacing.

[0075] Figure 1 The configuration utilizes different beam splitters (such as dichroic mirror 124 and beam splitter 156), different focusing elements (such as focusing element 126 and lens 160), and different sensors (such as imaging array 128 and sensor 162) to perform imaging (such as using dichroic mirror 124, focusing element 126, and imaging array 128) and focus sensing (such as using beam splitter 156, lens 160, and sensor 162). Alternatively, it may use a single beam splitter (such as dichroic mirror 124) and move a longitudinal orientation sensing element (such as...). Figure 1 Biprism, Figure 4 Split-field dichroic filter, Figure 5 LCOS devices or Figure 6 A chromatic aberration lens) positioned between the focusing element 126 and the imaging array 128 can be used to combine tasks and elements. If the end 106 of the fiber 108 is illuminated with multiple wavelengths, such as [missing information], they can be located within the reflection band of the dichroic mirror 124 (or if [missing information]). Figure 1 If the long-pass filter is replaced with a short-pass filter, then the three wavelengths (the transmission band) can be particularly effective.

[0076] Figure 7 It shows Figure 1 A top view of the longitudinal orientation adjuster element in system 100. Figure 1 and Figure 7 In this process, the longitudinal orientation adjuster element may include a zoom lens 166. The zoom lens 166 may be disposed in the optical path 112, such as in a fixed portion of the optical path 112. The processor 114 may further cause the zoom lens 166 to adjust the collimation of the beam 120 based on the longitudinal distance between the focal point and the end 106 of the optical fiber 108 (determined by the longitudinal orientation sensor element) to position the focal point at the end 106 of the optical fiber 108.

[0077] Figure 8 It shows the applicable Figure 1 A top view of an example of the longitudinal orientation adjuster element of system 100. As a result of using... Figure 1 and Figure 7 As an alternative to the zoom lens 166, system 100 may include a linear actuator 802 to longitudinally position the objective element 122 relative to the end 106 of the fiber 108, to longitudinally position the entire system 100 relative to the end 106 of the fiber 108, to longitudinally position the fiber 108 relative to system 100, or to otherwise controllably change the spacing between system 100 and the end 106 of the fiber 108. Processor 114 may control the linear actuator 802 based on the longitudinal spacing determined by a longitudinal orientation sensor element. Linear actuator 802 may adjust the spacing between the focal point and the end 106 of the fiber 108. Other suitable actuators and actuator types may also be used.

[0078] Any or all longitudinal orientation sensor technologies (such as those using...) Figure 1 Biprism, Figure 4 Split-field dichroic filter, Figure 5 LCOS devices Figure 6 Chromatic lenses or other technologies can be used with any or all longitudinal orientation adjuster technologies (such as those using...). Figure 1 and Figure 7 zoom lens, Figure 8 Linear actuators or others. In addition, any or all longitudinal orientation sensor technologies and any or all longitudinal orientation adjuster technologies can be used with any or all configurations of objective elements (such as objective lenses or objective mirrors), any or all configurations of optical fibers (such as single-core or multi-core), any or all configurations of light sources (such as single-core fiber, multi-core fiber, multiple single-core fibers, etc.), and any or all configurations of pivotable elements (such as including two, omitting one and including only one, omitting two and not including any, or including more than two).

[0079] Figure 9 A flowchart illustrating an example of a method 900 for guiding light into an optical fiber using an operating system is shown. The system may include imaging optics, a processor, and an actuable optical element. The actuable optical element may define an optical path. The optical path may extend to the actuable optical element and may further extend to the end of the optical fiber. Method 900 can... Figure 1 It can be executed on System 100 or any other suitable system.

[0080] At operation 902, the system can use imaging optics to generate an image of the end of the optical fiber.

[0081] At operation 904, the system can use the processor to determine the location of a specified feature in the image.

[0082] At operation 906, the system can use the processor to actuate actuable optical element based on the location of specified features in the image to align the optical path with the core of the optical fiber.

[0083] At operation 908, the system can guide the beam along the optical path to couple it into the core of the optical fiber.

[0084] In some examples, method 900 may optionally further include using a processor to determine an offset between the location of a specified feature in the image and a predetermined target location in the image. Method 900 may optionally further include using a processor to actuate an actuable optical element to reduce the offset.

[0085] In some examples, the specified feature may be the circumferential edge of the end of the optical fiber. The core may be located at a predetermined core position relative to the circumferential edge of the optical fiber. Method 900 may optionally further include using a processor to actuate an actuable optical element to align the optical path with the core in such a way that the optical path is aligned with the predetermined core position.

[0086] In some examples, method 900 may optionally further include illuminating the optical fiber with an illumination having a wavelength different from that of the light beam.

[0087] In some examples, method 900 may optionally further include at least some of the illumination reflected or scattered from the optical fiber to form a first light. Method 900 may optionally further include collimating at least some of the first light using an objective element of an imaging optics to form a second light. Method 900 may optionally further include guiding at least some of the second light away from the optical path using a dichroic mirror of the imaging optics to form a third light. Method 900 may optionally further include focusing the third light using a focusing element of the imaging optics to form an image at the focal plane of the focusing element. Method 900 may optionally further include sensing the image using an imaging array located at the focal plane of the focusing element.

[0088] In some examples, method 900 may optionally further include detecting the longitudinal spacing between the focal point and the end of the optical fiber using a longitudinal orientation sensor. Method 900 may optionally further include positioning the focal point using a longitudinal orientation adjuster to reduce the longitudinal spacing.

[0089] In some examples, the longitudinal orientation adjuster can further create a replica feature in the image. Method 900 may optionally further include determining the longitudinal spacing between the focal point and the end of the fiber by a processor and at least in part based on the spacing or size difference between the specified feature and the corresponding replica feature.

[0090] In some examples, the longitudinal orientation adjuster may include a zoom lens disposed in the optical path. Method 900 may optionally further include, via a processor and based on the longitudinal spacing between the focal point and the end of the optical fiber, adjusting the collimation of the beam to position the focal point at the end of the optical fiber.

[0091] In some examples, the longitudinal orientation adjuster may include an operable endoscope lens that can guide the optical path to the end of the optical fiber. Method 900 may optionally further include, via a processor and based on the longitudinal spacing between the focal point and the end of the optical fiber, moving the operable endoscope lens to position the focal point at the end of the optical fiber.

[0092] Figure 10 A flowchart illustrating an example of another method 1000 for guiding light into an optical fiber using an operating system is shown. The optical fiber may include a core. The system may include imaging optics, a first actuable optical element, and a second actuable optical element. Method 1000 can be... Figure 1 It can be executed on System 100 or any other suitable system.

[0093] At operation 1002, the system can use imaging optics to generate a first image of the end of the optical fiber.

[0094] At operation 1004, the system can determine the two-dimensional lateral position of the core at the end of the optical fiber based on the first image.

[0095] At operation 1006, the system can actuate the first actuable optical element based on the two-dimensional lateral position to laterally align the optical path with the core. Method 1000 may repeat operations 1002 to 1006 as needed until the system can determine that the optical path is sufficiently aligned with the core. When the system completes operation 1006, the optical path is considered to be laterally aligned with the core (e.g., aligned in the xy plane orthogonal to the optical path at the end of the fiber).

[0096] At operation 1008, the system can use imaging optics to generate a second image of the end of the optical fiber.

[0097] At operation 1010, the system can determine the longitudinal position of the core at the end of the optical fiber based on the second image.

[0098] At operation 1012, the system can actuate a second actuable optical element based on its longitudinal position to bring the optical path to a focal point at the end of the optical fiber. Method 1000 may repeat operations 1008 to 1006 as needed until the system can determine that the focal point is sufficiently close to the end of the optical fiber. When the system completes operation 1012, the focal point of the optical path is considered to be longitudinally aligned with the end of the optical fiber (e.g., aligned in the z-direction of the optical path parallel to the end of the optical fiber).

[0099] In some examples, the first actuable optical element may include a pivotable mirror. Method 1000 may optionally further include guiding a beam along an optical path to couple it into the core of an optical fiber. Method 1000 may optionally further include repeatedly performing at least the following three operations: First, the system can jitter the angular azimuth of the pivotable mirror in two dimensions. Second, the system can sense the amount of light reflected from the core. In some examples, the second operation may be performed by an interrogator of a controller coupled to the system. Third, the system can adjust the angular azimuth of the pivotable mirror to increase the amount of light reflected from the core.

[0100] In some examples, at least one of the controllers or processors included in the system can perform measurements at multiple angular azimuths (x, y) and / or multiple focal azimuths (z) of the pivotable mirror, measure the amount of light reflected from the core at each angular azimuth and / or focal azimuth, fit one or more curves to the measured amount of light, and adjust the angular azimuth and / or focal adjustment of the pivotable mirror to correspond to the local maximum value of one or more curves.

[0101] In some examples, controller 10 can use OFDR to measure the reflected signal at each location in mirror search mode. Various data processing techniques can be used to evaluate where optimal fiber coupling is achieved (e.g., which interval between the focal point of beam 120 and the end 106 of fiber 108 provides the highest amount of light returning from fiber 108, and therefore provides the highest coupling efficiency into fiber 108).

[0102] In one technique, the controller 10 can sum the reflection amplitudes in the raw frequency domain data and report the total reflection amplitude. Such a technique will work, but it can also exclude some relatively large background signals. The technique described below can exclude these relatively large background signals and thus increase the signal-to-noise ratio of the coupling efficiency measurement.

[0103] In another technique, controller 10 can select a segment of the reflection amplitude in the time domain or optical delay domain, representing a segment of the fiber 108 with a grating in the core, and sum over the selected segment. For example, in the time domain, because the horizontal axis corresponds to the round-trip propagation time, reflections generated by optical interfaces (such as the interface between glass and air, or the surface of a lens or window) appear as peaks along the horizontal axis. In this way, controller 10 can effectively ignore peaks generated from these optical interfaces and analyze data generated from light reflected from locations along the length of fiber 108. Controller 10 can sum the reflection amplitudes of data caused by reflections(one or more) along the length of fiber 108 and exclude data caused by reflections(one or more) from the end(s) of fiber 108 or other optical surfaces. Selecting which data to use in this way can increase sensitivity compared to using all light returning to controller 10. For example, selecting which data to use in this way can only show a higher signal (e.g., above the noise level) when light is coupled into fiber 108 and reflected from the grating structure along the length of fiber 108.

[0104] In another technique, controller 10 can select the entire fiber 108 region where the grating exists in the time domain, such as by transforming the data to the frequency domain via a fast Fourier transform and summing the amplitude only over the spectral region where the grating is reflected. Processing amplitude data in this way can help reduce or eliminate low-level broadband reflection amplitudes that may be caused by connector reflections and other optical interfaces.

[0105] A computer-readable medium may store instructions that, when executed by a processor of a system for guiding light into an optical fiber, cause the processor to perform operations. The system may include actuable optical elements defining an optical path. The optical path may extend to the actuable optical elements and may further extend to the end of the optical fiber. These operations may include at least the following four operations: First, the system may generate an image of the end of the optical fiber using imaging optics. Second, the system may determine the position of a specified feature in the image based on the image. Third, the system may actuate the actuable optical elements based on the position of the specified feature in the image to align the optical path with the core of the optical fiber. Fourth, the system may guide the light beam along the optical path to couple it into the core of the optical fiber.

[0106] Although various aspects of the invention have been described with reference to preferred embodiments, it will be understood that the invention is entitled to full protection within the scope of the appended claims.

Claims

1. A system for directing light into a multicore optical fiber, the multicore optical fiber comprising a plurality of cores, the system comprising: an actuatable optical element configured to define a plurality of optical paths, wherein the plurality of optical paths extend to the actuatable optical element and further extend to a distal end of the multicore optical fiber; an illumination light source configured to illuminate the distal end of the multicore optical fiber with illumination, such that at least some of the illumination reflects or scatters from the multicore optical fiber to form first light; an objective element configured to collimate at least some of the first light to form second light; a focusing element configured to focus the second light to form an image of the distal end of the multicore optical fiber at a focal plane of the focusing element; an imaging array located at the focal plane of the focusing element and configured to sense the image; and a processor configured to: determine a location of a specified feature in the image, and based on the location of the specified feature in the image, cause the actuatable optical element to actuate to simultaneously align each of the plurality of optical paths with a corresponding core of the plurality of cores; and a plurality of light sources configured to, for each of the plurality of optical paths, direct a light beam along that optical path to couple into the corresponding core of that optical path, wherein the illumination has a different wavelength than the light beams directed by the plurality of light sources.

2. The system of claim 1, wherein the processor is configured to cause the actuatable optical element to actuate to simultaneously align each of the plurality of optical paths with the corresponding core by: determining a shift between the location of the specified feature in the image and a predetermined target location in the image; and causing the actuatable optical element to actuate to reduce the shift.

3. The system of claim 1, wherein: the specified feature is a circumferential edge of the distal end of the multicore optical fiber; each corresponding core of the plurality of cores is located at a predetermined core location relative to the circumferential edge of the multicore optical fiber; and the processor is configured to cause the actuatable optical element to actuate to simultaneously align each of the plurality of optical paths with the corresponding core by: for each of the plurality of optical paths, causing the optical path to align with the predetermined core location of the corresponding core.

4. The system of claim 1, further comprising: a dichroic mirror configured to direct at least some of the second light away from the optical paths prior to focusing the second light at the focal plane of the focusing element.

5. The system of claim 1, wherein: the objective element comprises an objective lens; and the optical paths extend through the objective lens.

6. The system of claim 1, wherein the objective element comprises an objective mirror having a cross-section comprising a segment of a parabola.

7. The system of claim 1, wherein: the actuatable optical element comprises a pivotable mirror; the pivotable mirror is configured to pivot about a pivot axis that is parallel to a plane of the multicore optical fiber; and the pivotable mirror is configured to pivot about the pivot axis to simultaneously align each of the plurality of optical paths with the corresponding core of the plurality of cores. the processor is configured to actuate the actuatable optical element to align each of the plurality of optical paths with the corresponding core by: pivoting the pivotable minor to steer the optical paths based on the locations of the specified features in the image; and each of the plurality of optical paths includes a fixed portion extending between the plurality of light sources and the pivotable mirror and a movable portion extending between the pivotable mirror and the end of the multicore optical fiber.

8. The system of claim 7, wherein the pivotable mirror is located in the plurality of optical paths to be telecentric such that pivoting the pivotable mirror produces a lateral translation of the plurality of optical paths at the end of the multicore optical fiber without producing an angular change in the plurality of optical paths at the end of the multicore optical fiber.

9. The system of claim 1, wherein: the plurality of light sources are cores of a source optical fiber; and for each of the plurality of optical paths, the optical path extends to the actuatable optical element by extending from a core of the source optical fiber to the actuatable optical element such that at least some light from the light beam is configured to reflect from a length of the multicore optical fiber and propagate along the optical path to couple into the core of the source optical fiber.

10. The system of claim 9, wherein: the illumination light source is a first illumination light source configured to illuminate the multicore optical fiber with first illumination having a first wavelength different from wavelengths of the light beams directed by the plurality of light sources, the system further comprises: a second illumination light source configured to illuminate the source optical fiber with second illumination having a second wavelength different from the first wavelength and different from the wavelengths of the light beams directed by the plurality of light sources, at least some of the second illumination is configured to reflect or scatter from the source optical fiber to form third light; a source objective element configured to collimate at least some of the third light to form fourth light; and a dichroic mirror and a reflector configured to superimpose the second light and the fourth light to form fifth light; wherein the focusing element is configured to focus the fifth light to form an image of both the multicore optical fiber and the source optical fiber at the focal plane of the focusing element.

11. The system of any one of claims 1 to 9, wherein: the objective element is further configured to focus the light beams directed by the plurality of light sources to form a focal point proximate to the end of the multicore optical fiber; a longitudinal position sensor configured to detect a longitudinal separation between the focal point and the end of the multicore optical fiber; and a longitudinal position adjuster configured to longitudinally position the focal point to reduce the longitudinal separation.

12. The system of claim 11, wherein: the longitudinal position sensor includes a biprism configured to receive reflected light reflected from the end of the multicore optical fiber; the dual prism is further configured to impart a wedge angle between opposite halves of the reflected light such that the designated feature in the image has a corresponding replicated feature in the image; and the processor is further configured to determine the longitudinal separation between the focal point and the end of the multicore fiber based at least in part on a separation between the designated feature and the corresponding replicated feature.

13. The system of claim 11, wherein: the longitudinal position sensor includes a split field dichroic filter configured to receive reflected light from the end of the multicore fiber and having a plurality of wavelengths, the split field dichroic filter configured such that the designated feature in the image has a corresponding replicated feature in the image at different wavelengths; and the processor is further configured to determine the longitudinal separation between the focal point and the end of the multicore fiber based at least in part on a separation between the designated feature and the corresponding replicated feature.

14. The system of claim 11, wherein: the longitudinal position sensor includes a chromatic aberration lens configured to receive reflected light from the end of the multicore fiber and having a plurality of wavelengths, the chromatic aberration lens configured such that the designated feature in the image has a corresponding replicated feature in the image at different wavelengths; and the processor is further configured to determine the longitudinal separation between the focal point and the end of the multicore fiber based at least in part on a size of the designated feature in the image and a size of the corresponding replicated feature in the image.

15. The system of claim 11, wherein: the longitudinal position adjuster includes a zoom lens disposed in the optical path; and the processor is further configured to cause the zoom lens to adjust a collimation of the light beam based on the longitudinal separation between the focal point and the end of the multicore fiber to position the focal point at the end of the multicore fiber.

16. The system of claim 11, wherein: the longitudinal position adjuster includes a movable objective lens configured to direct the optical path onto the end of the multicore fiber; and the processor is further configured to cause the movable objective lens to move to position the focal point at the end of the multicore fiber based on the longitudinal separation between the focal point and the end of the multicore fiber.

17. The system of claim 11, wherein: the objective element is configured to focus the light beam at a focal plane proximate the end of the multicore fiber; the longitudinal position sensor is configured to detect the longitudinal separation by detecting a separation between the focal plane and the end of the multicore fiber; and the longitudinal position adjuster is configured to longitudinally position the focal plane.

18. The system of claim 1, wherein each of the plurality of light sources includes a source core of a source multicore fiber.

19. The system of claim 1, wherein: each light source of the plurality of light sources comprises a single-core optical fiber of a plurality of single-core optical fibers; and the system further comprises magnifying optics configured to provide a magnification to the plurality of optical paths, the magnification equal to a ratio of a pitch between adjacent cores of the plurality of cores of the multi-core optical fiber to a pitch between adjacent cores of the plurality of single-core optical fibers.

20. A method for operating a system to direct light into a multi-core optical fiber, the multi-core optical fiber comprising a plurality of cores, the system comprising an illumination light source, an objective element, a focusing element, an imaging array located at a focal plane of the focusing element, a processor, and an actuatable optical element defining a plurality of optical paths, each optical path of the plurality of optical paths extending to the actuatable optical element and further extending to a distal end of the multi-core optical fiber, the method comprising: illuminating the distal end of the multi-core optical fiber with illumination using the illumination light source such that at least some of the illumination reflects or scatters from the multi-core optical fiber to form first light; collimating at least some of the first light using the objective element to form second light; focusing the second light using the focusing element to form an image of the distal end of the multi-core optical fiber; sensing the image using the imaging array; determining, using the processor, a location of a specified feature in the image; causing, using the processor and based on the location of the specified feature in the image, the actuatable optical element to actuate to simultaneously align each optical path of the plurality of optical paths with a corresponding core of the plurality of cores; and directing, using a plurality of light sources and for each optical path of the plurality of optical paths, a light beam along the optical path to couple into the corresponding core of the optical path, wherein the illumination has a different wavelength than the light beams directed by the plurality of light sources.

21. The method of claim 20, wherein causing the actuatable optical element to actuate to simultaneously align each optical path of the plurality of optical paths with the corresponding core comprises: determining, using the processor, an offset between the location of the specified feature in the image and a predetermined target location in the image; and causing, using the processor, the actuatable optical element to actuate to reduce the offset.

22. The method of claim 20, wherein: the specified feature is a circumferential edge of the distal end of the multi-core optical fiber; each corresponding core of the plurality of cores is located at a predetermined core location relative to the circumferential edge of the multi-core optical fiber; and causing, using the processor, the actuatable optical element to actuate to simultaneously align each optical path of the plurality of optical paths with the corresponding core comprises, for each optical path of the plurality of optical paths, aligning the optical path with the predetermined core location of the corresponding core.

23. The method of claim 20, further comprising: directing, using a dichroic mirror, at least some of the second light away from the optical paths prior to focusing the second light at the focal plane.

24. The method of any of claims 20-23, further comprising: detecting, by a longitudinal position sensor, a longitudinal separation between a focal point and the tip of the multicore optical fiber; and positioning, with a longitudinal position adjuster, the focal point to reduce the longitudinal separation.

25. The method of claim 24, wherein the longitudinal position adjuster is further configured to create a replicated feature in the image, and wherein the method further comprises: determining, by the processor and based at least in part on a difference in spacing or size between the specified feature and the replicated feature, the longitudinal separation between the focal point and the tip of the multicore optical fiber.

26. The method of claim 24, wherein the longitudinal position adjuster comprises a zoom lens disposed in the optical path, and wherein the method further comprises: causing, by the processor and based on the longitudinal separation between the focal point and the tip of the multicore optical fiber, the zoom lens to adjust the collimation of the light beams directed by the plurality of light sources to position the focal point at the tip of the multicore optical fiber.

27. The method of claim 24, wherein the longitudinal position adjuster comprises an actuable objective lens configured to direct the optical path onto the tip of the multicore optical fiber, and wherein the method further comprises: causing, by the processor and based on the longitudinal separation between the focal point and the tip of the multicore optical fiber, the actuable objective lens to move to position the focal point at the tip of the multicore optical fiber.

28. The method of claim 24, further comprising: focusing, with the objective element, the light beams directed by the plurality of light sources at a focal plane proximate the tip of the multicore optical fiber; wherein detecting the longitudinal separation comprises detecting a separation between the focal plane and the tip of the multicore optical fiber; and wherein positioning the focal point comprises positioning the focal plane.

29. A method for operating a system for directing light into a multicore optical fiber, the multicore optical fiber comprising a plurality of cores, the system comprising an illumination light source, an objective element, a first focusing element and a first imaging array located at a focal plane of the first focusing element, a second focusing element and a second imaging array located at a focal plane of the second focusing element, a first actuable optical element, and a second actuable optical element, the method comprising: illuminating, with the illumination light source, a tip of the multicore optical fiber with illumination such that at least some of the illumination reflects or scatters from the multicore optical fiber to form first light; collimating, with the objective element, at least some of the first light to form second light; focusing, with the first focusing element, a first portion of the second light to form a first image of the tip of the multicore optical fiber; sensing, with the first imaging array, the first image; determining, from the first image, two-dimensional lateral positions of a plurality of the plurality of cores on the tip of the multicore optical fiber; based on the two-dimensional transverse position, causing the first actuatable optical element to actuate to laterally align a plurality of optical paths to the plurality of cores; with a plurality of light sources and for each of the plurality of optical paths, directing a light beam along the optical path to couple into a corresponding core of the optical path, wherein the illumination has a different wavelength than the wavelengths of the light beams directed by the plurality of light sources; with the second focusing element, focusing a second portion of the second light to form a second image of the end of the multicore fiber; with the second imaging array, sensing the second image; from the second image, determining a longitudinal separation of a focal point of the light beam along the optical path from the end of the multicore fiber; and based on the longitudinal separation, causing the second actuatable optical element to actuate to bring the plurality of light beams to a focal point at a focal plane at the end of the multicore fiber.

30. The method of claim 29, wherein the first actuatable optical element comprises a pivotable mirror; and the method further comprises: directing a plurality of light beams along the plurality of optical paths to couple into the plurality of cores of the multicore fiber; and repeatedly: causing an angular orientation of the pivotable mirror to dither in two dimensions, sensing an amount of light reflected from at least one core of the multicore fiber, and adjusting the angular orientation of the pivotable mirror to increase the amount of light reflected from the core.

31. A computer-readable medium storing instructions for execution by a processor of a system for directing light into a multicore fiber comprising a plurality of cores, the system comprising: an actuatable optical element defining a plurality of optical paths extending to the actuatable optical element and further extending to an end of the multicore fiber, an illumination light source configured to illuminate the end of the multicore fiber with illumination such that at least some of the illumination reflects or scatters from the multicore fiber to form first light; an objective element configured to collimate at least some of the first light to form second light; a focusing element configured to focus the second light to form an image of the end of the multicore fiber at a focal plane of the focusing element; an imaging array at the focal plane of the focusing element and configured to sense the image; and a plurality of light sources configured to, for each of the plurality of optical paths, direct a light beam along the optical path to couple into a corresponding core of the optical path, wherein the illumination has a different wavelength than the wavelengths of the light beams directed by the plurality of light sources; the instructions, when executed by the processor, cause the processor to perform operations comprising: from the image, determining a location of a specified feature in the image; and based on the location of the specified feature in the image, causing the actuatable optical element to actuate to simultaneously align the plurality of optical paths to corresponding ones of the plurality of cores.

32. The computer-readable medium of claim 31, wherein causing the actuatable optical element to actuate to simultaneously align each of the plurality of optical paths to the corresponding core comprises: determining, with the processor, an offset between the location of the specified feature in the image and a predetermined target location in the image; and causing, with the processor, the actuatable optical element to actuate to reduce the offset.

33. The computer-readable medium of claim 31, wherein: the specified feature is a circumferential edge of the end of the multicore optical fiber; each corresponding core of the plurality of cores is located at a predetermined core location relative to the circumferential edge of the multicore optical fiber; and causing, with the processor, the actuatable optical element to actuate to simultaneously align each optical path of the plurality of optical paths with the corresponding core comprises, for each optical path of the plurality of optical paths, aligning the optical path with the predetermined core location of the corresponding core.

34. The computer-readable medium of claim 31, wherein the system further comprises: a longitudinal orientation sensor configured to create a replica feature in the image, and a longitudinal orientation adjuster configured to position a focal point of the light beam along the optical path, and wherein the operations further comprise: determining, by the processor and based at least in part on a spacing or size difference between the specified feature and the replica feature, a longitudinal separation between the focal point and the end of the multicore optical fiber, and causing the longitudinal orientation adjuster to reduce the longitudinal separation.

35. The computer-readable medium of claim 34, wherein the longitudinal orientation adjuster comprises a zoom lens disposed in the plurality of optical paths, and wherein the operations further comprise: causing, by the processor and based on the longitudinal separation between the focal point and the end of the multicore optical fiber, the zoom lens to adjust a collimation of the light beam to position the focal point at the end of the multicore optical fiber.

36. The computer-readable medium of claim 34, wherein the longitudinal orientation adjuster comprises an actuatable objective lens configured to direct the plurality of optical paths onto the end of the multicore optical fiber, and wherein the operations further comprise: causing, by the processor and based on the longitudinal separation between the focal point and the end of the multicore optical fiber, the actuatable objective lens to move to position the focal point at the end of the multicore optical fiber.

37. A computer-readable medium storing instructions for execution by a processor of a system for directing light into a multicore optical fiber, the multicore optical fiber comprising a plurality of cores, the system comprising: a first actuatable optical element; a second actuatable optical element; an illumination light source configured to illuminate an end of the multicore optical fiber with illumination such that at least some of the illumination reflects or scatters from the multicore optical fiber to form first light; an objective element configured to collimate at least some of the first light to form second light; a first focusing element configured to focus a first portion of the second light to form a first image of the end of the multicore optical fiber at a focal plane of the first focusing element; ​ a first imaging array at the focal plane of the first focusing element and configured to sense the first image; a second focusing element configured to focus a second portion of the second light to form a second image of the end of the multicore optical fiber at a focal plane of the second focusing element; a second imaging array at the focal plane of the second focusing element and configured to sense the second image; and a plurality of light sources configured to direct light beams along a plurality of optical paths to couple into corresponding ones of the plurality of cores, wherein the illumination has a different wavelength than the wavelengths of the light beams directed by the plurality of light sources; the instructions, when executed by the processor, cause the processor to perform operations comprising: determining, from the first image, two-dimensional lateral positions of a plurality of the plurality of cores on the end of the multicore optical fiber; based on the two-dimensional lateral positions, causing the first actuatable optical element to actuate to laterally align the plurality of optical paths to the plurality of cores; determining, from the second image, longitudinal positions of the plurality of cores relative to the end of the multicore optical fiber; and based on the longitudinal positions, causing the second actuatable optical element to actuate to bring the plurality of optical paths to a focus at a focal plane at the end of the multicore optical fiber.

38. The computer-readable medium of claim 37, wherein the first actuatable optical element comprises a pivotable mirror; and the operations further comprise: repeatedly: causing an angular orientation of the pivotable mirror to dither in two dimensions, and based on a sensed amount of light reflected from at least one core of the multicore optical fiber, causing the angular orientation of the pivotable mirror to adjust to increase the amount of light reflected from the core.

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