End caps for coherent fiber bundles enabling selective planar illumination microscopy, and coherent fiber bundle assemblies comprising the same.

Abstract

An end cap for a coherent fiber bundle (CFB) for enabling selective plane illumination microscopy (SPIM). The end cap comprises one or more CFB alignment features for aligning the end cap with respect to a distal end of the CFB, a sample space for receiving a sample or material to be imaged, and a peripheral reflector disposed at least partially around the sample space, the sample space extending from a front side of the end cap, the peripheral reflector being configured such that when the end cap is aligned with the distal end of the CFB, the peripheral reflector redirects excitation light output from a plurality of outer optical cores of the CFB, such that the redirected excitation light propagates at least partially across the sample space in front of the end face of the CFB for excitation of the sample or material in the sample space and generation of fluorescence therein, and at least a portion of the fluorescence is coupled into a plurality of inner optical cores of the CFB. The end cap can be used for enabling selective plane illumination microscopy (SPIM), including but not limited to enabling SPIM for clinical endoscopy.

Description

[Technical field]

[0001] The present disclosure relates to end caps for coherent fiber bundles (CFBs) to enable selective plane illumination microscopy (SPIM), particularly, but not exclusively, to enable SPIM for clinical endoscopy. [Background technology]

[0002] It is known to use coherent fiber bundles (CFBs) to minimally invasively transmit images for in vivo medical microscopy of various organs of the body, due to their narrow diameter (typically less than 1 mm), flexibility, and chemical and biological inertness. For example, it is known to use CFBs for urological, gastrointestinal, and respiratory endoscopy.

[0003] However, when using CFB in wide-field modalities, unwanted background fluorescence can be observed in images acquired through the fiber. This background originates from out-of-focus fluorescence emitted outside the image plane and can reduce the quality and / or contrast of images acquired through the CFB.

[0004] It is also known to use CFBs made of highly doped silica. However, such silica CFBs can be expensive. It is therefore known to use polymer CFBs because they can have larger diameter CFBs with higher core-cladding refractive index contrast, larger field of view, and are essentially manufactured using lower cost materials and equipment than silica CFBs. However, polymer CFBs can produce higher levels of autofluorescence when excited with near-UV or blue light than silica CFBs. This can be prohibitive, especially for fluorescence imaging at shorter wavelengths, for example, at wavelengths in the green region of the visible spectrum where many clinically relevant endogenous fluorophores fluoresce.

[0005] It is also known to perform selective plane illumination microscopy (SPIM) through a CFB. However, known systems for performing SPIM through a CFB use a separate excitation fiber next to the CFB. Furthermore, such known systems for performing SPIM through a CFB may rely on the use of one or more additional optical components at the distal end of the excitation fiber and / or the distal end of the CFB. For example, such known systems for performing SPIM through a CFB may include a GRIN lens at the distal end of the excitation fiber and / or a GRIN lens at the distal end of the CFB. Such known systems for performing SPIM through a CFB may use microprisms to generate the excitation light sheet for SPIM. As a result, such known systems for performing SPIM through a CFB may be complex and cumbersome and may have a distal end cross section of several millimeters or more, with much of this space being occupied by the additional optical components at the distal end of the excitation fiber. This may also reduce the field of view. Thus, the use of such known systems for performing SPIM through a CFB may be prohibitive for SPIM in some endoscopic applications that require a smaller cross section and / or a larger field of view.

[0006] It is also known to use structured illumination microscopy through a CFB, whereby an illumination pattern is projected onto the sample being imaged to minimize out-of-focus fluorescent background. However, the use of structured illumination microscopy through a CFB can introduce motion artifacts into the image of the sample. Furthermore, known systems that use structured illumination microscopy through a CFB do not address the occurrence of any autofluorescence background in the CFB itself. Summary of the Invention

[0007] According to one aspect of the present disclosure, there is provided an end cap for a coherent fiber bundle (CFB) for enabling selective plane illumination microscopy (SPIM), comprising: one or more CFB alignment features for aligning the end cap relative to a distal end of the CFB; a sample space for receiving a sample or material to be imaged, the sample space extending from a front side of the end cap; a peripheral reflector disposed at least partially around the sample volume; An end cap is provided in which, when the end cap is aligned with said distal end of the CFB, the peripheral reflector is configured to redirect excitation light output from the multiple outer optical cores of the CFB, such that the redirected excitation light propagates at least partially across a sample space in front of the end face of the CFB for excitation of a sample or material in the sample space and generation of fluorescence therein, and at least a portion of the fluorescence is coupled into the multiple inner optical cores of the CFB.

[0008] Such an end cap can be aligned and / or placed at the distal end of the CFB. The end cap can be configured to accept excitation light delivered through the outer optical core and redirect the excitation light to propagate at least partially across the sample space in front of the end face of the CFB, forming a light sheet that may be approximately parallel to the end face of the CFB, for example. This allows the CFB to be used for SPIM of any sample or material located within the sample space.

[0009] Furthermore, the fluorescence emitted from the excited sample or material is captured by the inner optical core of the CFB and an image of the fluorescence is transmitted by the inner optical core of the CFB back to an image sensor located at the proximal end of the CFB. The use of such an end cap therefore means that the inner optical core of the CFB is not excited by the excitation light, thereby avoiding or at least partially suppressing the generation of any autofluorescence background in the inner optical core of the CFB. This can improve image quality and / or image contrast, especially when end caps are used with polymer CFBs, which can generate strong fiber autofluorescence background.

[0010] The use of such end caps with polymeric CFBs may be advantageous for endoscopy, particularly because polymeric materials such as PMMA can be manufactured into CFBs that are more flexible and less brittle than CFBs formed from glass materials such as silica. For example, a PMMA CFB having an outer diameter of 1.5 mm has been found to be flexible enough to be deployed under an endoscope, whereas a glass CFB of the same diameter is too rigid to be deployed under an endoscope. The use of a CFB assembly comprising such an end cap attached to the distal end of a polymeric CFB may be particularly advantageous for robotic assisted endoscopy, where a flexible, less brittle CFB assembly is required.

[0011] The placement of an end cap at the distal end of the CFB can enable SPIM such that only the region of the sample or material in the sample space that is proximal to the end of the CFB and therefore in focus is excited. Thus, the use of an end cap can avoid or at least partially suppress the occurrence of out-of-focus fluorescent background in the sample or material.

[0012] The end cap is also suitable for use with a single CFB avoiding the need for any additional optical fibers. The end cap also avoids the need to use additional optical components, such as one or more GRIN lenses and / or prisms, at the distal end of the CFB. For all of these reasons, the use of the end cap allows for a reduced footprint or volume compared to prior art fiber optic SPIM systems. In particular, when the end cap is installed at the distal end of the CFB, the resulting assembly may be smaller in diameter compared to known CFB assemblies for SPIM. The use of the end cap may also provide a larger field of view than known CFB assemblies for SPIM. These features may make the end cap advantageous for clinical applications.

[0013] Optionally, the peripheral reflector is annular or approximately annular.

[0014] Optionally, the peripheral reflector defines a reflector surface that extends at least partially around the sample space.

[0015] Optionally, the end cap defines a longitudinal axis for alignment with a longitudinal axis of the CFB.

[0016] Optionally, the end cap is cylindrically symmetric about the longitudinal axis.

[0017] Optionally, a normal to the reflector surface extends along a direction having a radially outward component relative to the longitudinal axis of the end cap.

[0018] Optionally, the reflector surface has a linear profile when viewed in a longitudinal cross section of the end cap that includes the longitudinal axis of the end cap.

[0019] Optionally, the reflector surface has a curved profile when viewed in a longitudinal cross section of the end cap that includes the longitudinal axis of the end cap.

[0020] Optionally, the curved profile of the reflector surface is outwardly convex relative to the longitudinal axis of the end cap.

[0021] Optionally, the peripheral reflector includes a reflective material or coating formed on, disposed on, or covering the reflector surface.

[0022] Optionally, the reflective material or coating comprises a metal.

[0023] Optionally, the reflective material or coating comprises silver.

[0024] Optionally, the end cap comprises a peripheral lens disposed at least partially around the sample space and positioned radially between the peripheral reflector and the sample space relative to the longitudinal axis, the peripheral lens configured to concentrate or focus the redirected excitation light as it propagates at least partially across the sample space in front of the end face of the CFB toward the longitudinal axis of the end cap.

[0025] Optionally, the peripheral lens is configured to collect or focus the redirected excitation light on the longitudinal axis of the end cap.

[0026] Optionally, the peripheral lens defines an inwardly convex lens contour relative to a longitudinal axis of the end cap.

[0027] Optionally, the peripheral lens at least partially defines the sample space.

[0028] Optionally, the peripheral lens is annular or approximately annular.

[0029] Optionally, a normal to the reflector surface extends along a direction having a radially inward component relative to the longitudinal axis of the end cap.

[0030] Optionally, the curved profile of the reflector surface is inwardly concave relative to the longitudinal axis of the end cap.

[0031] Optionally, the one or more CFB alignment features comprise a rear space for receiving a distal end of the CFB, the rear space extending from a rear side of the end cap.

[0032] Optionally, the end cap defines a passageway extending from a rear side of the end cap to a front side of the end cap.

[0033] Optionally, the rear space comprises a wider rear section of the passageway, such as a wider diameter rear section of the passageway.

[0034] Optionally, the sample space comprises a narrower front section of the passageway, such as a narrower diameter front section of the passageway.

[0035] Optionally, the end cap is annular or generally annular.

[0036] Optionally, the sample space comprises a front recess defined in a front side of the end cap.

[0037] Optionally, the rear space comprises a rear recess defined in a rear side of the end cap.

[0038] Optionally, the end cap comprises an intervening portion configured to extend between the front recess and an end face of the CFB at the distal end of the CFB when the end cap is aligned with the distal end of the CFB. Such an intervening portion can separate the end face of the CFB from the sample or material in the front recess. Such an intervening portion may be configured to transmit at least a portion of the fluorescent light to the multiple inner optical cores of the CFB when the end cap is aligned with the distal end of the CFB.

[0039] Optionally, the intervening portion extends between the front and rear recesses.

[0040] Optionally, the end cap is unitary.

[0041] Optionally, the end cap comprises first and second portions, the first and second portions comprising one or more complementary alignment features for aligning the first and second portions relative to one another.

[0042] Optionally, the first portion defines one or more CFB alignment features, and the first and second portions together define a peripheral reflector.

[0043] Optionally, the first portion defines one or more CFB alignment features and a reflector surface of the peripheral reflector, and the second portion defines a reflective material or coating that covers the reflector surface when the first and second portions are aligned.

[0044] Optionally, the first portion defines one or more CFB alignment features, and the second portion defines a peripheral reflector.

[0045] Optionally, the end cap is configured for use with a coherent fiber bundle (CFB) that includes or is formed from a polymeric material, such as PMMA.

[0046] Optionally, the end cap is configured for use with a coherent fiber bundle (CFB) that includes or is formed from a glass material.

[0047] Optionally, the end cap is configured such that when the end cap is aligned with respect to the distal end of the CFB, the peripheral reflector redirects excitation light output from the multiple outer optical cores of the CFB such that the redirected excitation light propagates at least partially across the sample space in front of the end face of the CFB for excitation of a sample or material in the sample space and generation of Raman scattered light therein, and at least a portion of the Raman scattered light is coupled into the multiple inner optical cores of the CFB. Such an end cap can be used for SPIM imaging of Raman scattered light.

[0048] Optionally, the end cap includes or is formed from a material that is transparent or substantially transparent to the excitation light.

[0049] Optionally, the end cap includes or is formed from a material that is transparent or substantially transparent to fluorescent light.

[0050] Optionally, the end caps include or are formed from a material that is transparent or substantially transparent to Raman scattered light.

[0051] Optionally, the end caps include or are formed from fused silica.

[0052] Optionally, the end caps are formed by exposing one or more regions of the substrate to light and selectively chemically etching away material of the substrate from the one or more exposed regions. Exposing one or more regions of the substrate to light can enhance the chemical etchability of the material of the substrate in the one or more exposed regions of the substrate.

[0053] Optionally, exposing one or more regions of the substrate to light includes using ultrafast laser inscription of the one or more regions of the substrate.

[0054] Optionally, the end caps are disposable.

[0055] According to one aspect of the present disclosure, a coherent fiber bundle (CFB) assembly for a SPIM is provided, the CFB assembly comprising a coherent fiber bundle (CFB) and the above-mentioned end cap attached to a distal end of the CFB.

[0056] Optionally, the CFB includes or is formed from a polymeric material, such as PMMA.

[0057] Optionally, the CFB includes or is formed from a glass material.

[0058] Optionally, the CFB assembly includes an adhesive, such as an epoxy, between the end cap and the distal end of the CFB to attach or secure the end cap to the distal end of the CFB.

[0059] Optionally, the CFB assembly includes an end cap and an outer sleeve around a distal end of the CFB.

[0060] Optionally, the outer sleeve includes or is formed from heat shrink tubing.

[0061] It should be understood that any one or more of the features of any one of the aforementioned aspects of the present disclosure may be combined with any one or more of the features of any of the other aforementioned aspects of the present disclosure.

[0062] An end cap for a coherent fiber bundle (CFB) to enable selective plane illumination microscopy (SPIM), and a CFB assembly including a CFB and an end cap will now be described, by way of non-limiting example only, with reference to the drawings. [Brief description of the drawings]

[0063] [Figure 1] FIG. 1 is a schematic diagram of a fluorescence endoscopy system for lung imaging. [Diagram 2] FIG. 2 is a schematic longitudinal cross-sectional view of an end cap for a coherent fiber bundle (CFB) of the fluorescence endoscope system of FIG. 1 to enable selective plane illumination microscopy (SPIM). [Figure 3A] 1 is a side view microscope image of a region of a fused silica substrate after femtosecond laser inscription of the fused silica substrate to define the geometry of an end cap, but prior to chemical etching of the inscribed region of the fused silica substrate. [Figure 3B] FIG. 3B is a top view microscope image of the same area of ​​the fused silica substrate shown in FIG. 3A after femtosecond laser inscription of the fused silica substrate to define the geometry of the end caps, but prior to chemical etching of the inscribed areas of the fused silica substrate. [Figure 3C] An image of a 10x10x1 mm substrate of fused silica onto which twelve end cap segments have been imprinted. [Figure 4A]FIG. 13 is a side view microscope image of a first portion of a fused silica end cap after a KOH etching process. [Figure 4B] 13 is a top view microscope image of a second portion of the fused silica end cap after a KOH etching process. [Figure 4C] 4B is a microscope image of a first portion of the end cap of FIG. 4A in a slightly angled position. [Figure 5A] 4B is an image of the first portion of the fused silica end cap of FIG. 4A and the second portion of the fused silica end cap bonded together to form the end cap. [Figure 5B] FIG. 5B is an image of the fused silica end cap of FIG. 5A bonded to a PMMA CFB. [Figure 5C] FIG. 5B is an image of the distal end of the CFB assembly in which the fused silica end cap of FIG. 5A is bonded to the PMMA CFB and includes protective heat shrink tubing around the fused silica cap. [Figure 6] FIG. 2 is a schematic diagram of the proximal end instrumentation of the fluorescence endoscope system of FIG. 1. [Figure 7A] 1 shows an acquired image of a first tissue phantom without selective planar illumination. [Figure 7B] 1 shows an acquired image of a first tissue phantom with selective planar illumination. [Figure 8A] 13 shows an image acquired of a second tissue phantom without selective planar illumination. [Figure 8B] 13 shows an image acquired of a second tissue phantom with selective planar illumination. [Figure 9A] 13 shows an image acquired of a third tissue phantom without selective planar illumination. [Figure 9B] 13 shows an image acquired of a third tissue phantom with selective planar illumination. [Figure 10] FIG. 2 is a schematic longitudinal cross-sectional view of an alternative end cap for a coherent fiber bundle (CFB) of the fluorescence endoscope system of FIG. 1 to enable selective plane illumination microscopy (SPIM). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0064] Referring initially to FIG. 1 , there is shown a fluorescence endoscopy system, generally indicated at 2, for use during fluorescence endoscopy of the lungs. The fluorescence endoscopy system 2 comprises a bronchoscope 4, a coherent fiber bundle (CFB) assembly, generally indicated at 6, and instrumentation 8 connected to a proximal end of the CFB assembly 6. The coherent fiber bundle (CFB) assembly comprises a polymeric CFB 10, which may include or be formed from polymethylmethacrylate (PMMA), a generally annular end cap 12 attached to a distal end of the CFB 10, and an outer protective sleeve in the form of some heat shrink tubing 14 around the end cap 12. As will be described in detail below, the CFB assembly 6 is inserted using the bronchoscope 4 via the trachea 20, the main bronchi 22, and one of the bronchioles 24 into one of the alveoli, and the CFB assembly 6 is used for selective plane illumination microscopy (SPIM) of a sample or material to be imaged in the form of tissue in an alveolar sac 26 of the lung 28.

[0065] 2, the end cap 12 comprises a generally annular first portion 12a and a generally annular second portion 12b, the first portion 12a and the second portion 12b being coaxially aligned along a longitudinal axis 48, the first portion 12a and the second portion 12b comprising one or more complementary alignment features for aligning the first portion 12a and the second portion 12b relative to one another. Specifically, the upper surface 30a of the first portion 12a and the lower surface 30b of the second portion 12b have complementary contours such that the features of the first portion 12a and the second portion 12b are aligned when the lower surface 30b of the second portion 12b and the upper surface 30a of the first portion 12a are engaged.

[0066] The end cap 12 defines a passageway extending from a rear side 42 of the end cap 12 to a front side 46 of the end cap 12. The first portion 12a of the end cap 12 includes one or more CFB alignment features in the form of a rear space for receiving a distal end of the CFB 10, the rear space being defined by a wider diameter rear section 40 of the passageway extending from the rear side 42 of the first portion 12a. The end cap 12 further includes a sample space for receiving a sample or material to be imaged, the sample space being defined by a narrower diameter front section 44 of the passageway extending from the front side 46 of the end cap 12. As a result, when the distal end of the CFB 10 is inserted into the wider diameter rear section 40 of the passageway, the distal end face 10a of the CFB 10 cannot protrude axially into the narrower diameter front section 44 of the passageway. The front and rear sections 44 and 40 of the passageway are coaxially aligned along a longitudinal axis 48 of the end cap 12 .

[0067] The first and second portions 12a, 12b together define a generally annular peripheral reflector 50 disposed about the front section 44 of the passageway. Specifically, the peripheral reflector 50 comprises a generally annular reflector surface 52 defined by the upper surface 30a of the first portion 12a and extending about the front section 44 of the passageway. As can be seen from FIG. 2, a normal to the reflector surface 52 extends along a direction having a radially outward component relative to the longitudinal axis 48 of the end cap 12. Furthermore, the reflector surface 52 has a curved profile when viewed in a longitudinal cross section of the end cap 12 that includes the longitudinal axis 48 of the end cap 12, the curved profile being outwardly convex relative to the longitudinal axis 48 of the end cap 12. Additionally, the underside 30b of the second portion 12a of the end cap 12 includes a reflective material or coating in the form of a silver coating 54, whereby when the underside 30b of the second portion 12b and the upper surface 30a of the first portion 12a are engaged, the silver coating 54 covers the reflector surface 52.

[0068] The first portion 12a of the end cap 12 further comprises a generally annular peripheral lens 60 disposed radially between the peripheral reflector 50 and the front section 44 of the passageway relative to the longitudinal axis 48. As shown in FIG. 2, the peripheral lens 60 at least partially defines the front section 44 of the passageway. Additionally, as can be seen from FIG. 2, the peripheral lens 60 defines an inwardly convex lens profile relative to the longitudinal axis 48 of the end cap 12.

[0069] Figure 3A is a side view microscope image of a region of a fused silica substrate, and Figure 3B is a top view microscope image of the same region of the fused silica substrate after femtosecond laser inscription of the fused silica substrate to define the geometry of end cap 12, but prior to chemical etching of the inscribed region of the fused silica substrate. Figure 3C is an image of a 10 x 10 x 1 mm substrate of fused silica inscribed with twelve end cap portions 12a.

[0070] Figure 4A is a side view microscope image of the first portion 12a of the end cap 12, and Figure 4B is a top view microscope image of the second portion 12b of the end cap 12 after a KOH etching process. Figure 4C is a microscope image of the first portion 12a of the end cap 12 in a slightly angled position.

[0071] Figure 5A is an image of the first and second portions 12a, 12b bonded together to form the end cap 12. Figure 5B is an image of the end cap 12 bonded to the PMMA CFB 10, showing the distal end surface 10a of the CFB 10. Figure 5C is an image of the distal end of the CFB assembly 6, showing the distal end surface 10a of the CFB 10 and the protective heat shrink tubing 14 around the fused silica cap 12.

[0072] 6 is a schematic diagram of proximal end instrumentation 8 in the form of an epifluorescence microscope comprising a laser 70, a single mode fiber optic patch cord 72, a collimating lens 74, a beam expander 76, and an excitation filter 78. The epifluorescence microscope further comprises an axicon lens 80, a first relay lens 81, a second relay lens 82, a dichroic mirror 84, and an objective lens 86. The epifluorescence microscope also comprises an emission filter 90, a focusing lens 92, an image sensor 94, and a computer 96. The image sensor 94 and the computer 96 are configured for communication.

[0073] In use, the proximal end instrumentation 8 provides ring excitation of a sample or material in the front section 44 of the passageway of the end cap 12 and acquires a fluorescence image of the sample or material in the front section 44 of the passageway. Specifically, light from the laser 70 is transmitted through a single mode fiber optic patch cord 72 and collimated by a collimating lens 74. The collimated beam is then expanded by a beam expander 76 and passes through an excitation filter 78. An axicon lens 80 converts the collimated beam into a ring-shaped beam. An image plane of the ring-shaped beam is then created by a first relay lens 81. This image plane is relay imaged via a dichroic mirror 84 with a second relay lens 82 and an objective lens 86 to the proximal end of the CFB 10 in the focal plane of the objective lens 86. The axicon lens 80 and relay lenses 81, 82 are configured to create a predetermined illumination ring at the proximal end of the CFB 10. Thus, only the outer optical core of the CFB 10, capped at the distal end of the CFB 10 by the peripheral reflector 50, is illuminated with excitation light from the laser 70. Additionally, the end cap 12 is configured such that the peripheral reflector 50 redirects the excitation light output from the outer optical core of the CFB 10 such that the redirected excitation light propagates at least partially across the front section 44 of the passage in front of the distal end face 10a of the CFB 10 for excitation of a sample or material in the front section 44 of the passage and generation of fluorescence therein, with at least a portion of the fluorescence being coupled into the multiple inner optical cores of the CFB 10. The peripheral lens 60 concentrates or focuses the redirected excitation light as it propagates at least partially across the front section 44 of the passage in front of the end face 10a of the CFB 10 toward the longitudinal axis 48 of the end cap 12 so as to form a sheet of excitation light in front of the end face 10a of the CFB 10.

[0074] The multiple inner optical cores of the CFB 10 transmit an image of the fluorescence emitted by the sample or material in the front section 44 of the passageway back to the proximal end of the CFB 10, where the image of the fluorescence emitted by the sample or material is imaged onto an image sensor 94 via an objective lens 86, a dichroic mirror 84, an emission filter 90, and a focusing lens 92.

[0075] The use of the end cap 12 means that the inner optical core of the CFB 10 is not excited by the excitation light, thereby avoiding or at least partially suppressing the occurrence of any autofluorescence background in the inner optical core of the polymer CFB 10. This can improve the quality and / or contrast of the image of the sample. The placement of the end cap 12 at the distal end of the CFB 10 can enable SPIM such that only the region of the sample or material in the front section 44 of the passage that is proximate to the end of the CFB 10 and therefore in focus is excited. The use of the end cap 12 can therefore avoid or at least partially suppress the occurrence of any out-of-focus fluorescence background in the sample or material.

[0076] The end cap 12 is also suitable for use with a single CFB 10 avoiding any need for any additional optical fibers. The end cap 12 also avoids the need for the use of additional optical components, such as one or more GRIN lenses and / or prisms, at the distal end of the CFB 10. For all of these reasons, the use of the end cap 12 allows for a CFB assembly 6 with a reduced footprint or volume compared to prior art fiber optic SPIM systems. In particular, when the end cap 12 is installed at the distal end of the CFB 10, the resulting assembly may be smaller in diameter compared to known CFB systems for SPIM. The use of the end cap 12 may also provide a larger field of view than known CFB systems for SPIM. These features may make the end cap 12 advantageous for clinical applications.

[0077] 7A and 7B show images of a first tissue phantom obtained without and with selective planar illumination, respectively, where the image in FIG. 7B was obtained using the CFB assembly 6 in combination with the proximal end instrumentation 8 of FIG. 6. Similarly, FIGS. 8A and 8B show images of a second tissue phantom obtained without and with selective planar illumination, respectively, where the image in FIG. 8B was obtained using the CFB assembly 6 in combination with the proximal end instrumentation 8 of FIG. 6, and FIGS. 9A and 9B show images of a third tissue phantom obtained without and with selective planar illumination, respectively, where the image in FIG. 9B was obtained using the CFB assembly 6 in combination with the proximal end instrumentation 8 of FIG. 6. As can be seen by comparing FIGS. 7B, 8B, and 9B with FIGS. 7A, 8A, and 9A, respectively, the use of the CFB assembly 6 including the end cap 12 and proximal end instrumentation 8 of FIG. 6 for SPIM results in improved image quality and / or improved image contrast.

[0078] 10, an alternative end cap 112 for use with the CFB 10 is shown. The alternative end cap 112 comprises a generally cylindrical first portion 112a and a generally annular second portion 112b, the first portion 112a and the second portion 112b being coaxially aligned along a longitudinal axis 148, and the first portion 12a and the second portion 12b comprising one or more complementary alignment features for aligning the first portion 112a and the second portion 112b relative to one another. Specifically, the upper surface 130a of the first portion 112a defines a generally annular ridge 132a and the lower surface 130b of the second portion 112b defines a generally annular groove 132b such that when the groove 132b of the second portion 112b and the ridge 132a of the first portion 112a interengage, the features of the first portion 112a and the second portion 112b are aligned.

[0079] The first portion 112a of the end cap 112 comprises one or more CFB alignment features in the form of a rear space in the form of a rear recess 140 for receiving a distal end of the CFB 110, the rear recess 140 extending from a rear side 142 of the first portion 112a. The end cap 112 further comprises a sample space in the form of a front recess 144 for receiving a sample or material to be imaged, the front recess 144 extending from a front side 146 of the end cap 112. The front and rear recesses 144, 140 are coaxially aligned along a longitudinal axis 148 of the end cap 112.

[0080] The second portion 112b defines a generally annular peripheral reflector 150 disposed about the front recess 144. Specifically, the peripheral reflector 150 comprises a generally annular reflector surface 152 defined by the lower surface 130b of the second portion 112b and extending about the front recess 144. As can be seen from FIG. 10 , a normal to the reflector surface 152 extends along a direction having a radially inward component relative to the longitudinal axis 148 of the end cap 112. Furthermore, the reflector surface 152 has a curved profile when viewed in a longitudinal cross section of the end cap 112 that includes the longitudinal axis 148 of the end cap 112, the curved profile being inwardly concave relative to the longitudinal axis 148 of the end cap 112. Additionally, the lower surface 130 b of the second portion 112 a of the end cap 112 includes a reflective material or coating in the form of a silver coating 154 formed or disposed on the reflector surface 152 .

[0081] The first portion 112a further comprises an intervening portion 134 configured to extend between the front recess 144 and an end face of the CFB at the distal end of the CFB 10 when the end cap 112 is aligned against the distal end of the CFB 10. Specifically, the intervening portion 134 extends between the front recess 144 and the rear recess 140. In use, the intervening portion 134 separates the end face of the CFB 10 from a sample or material within the front recess 144. The intervening portion 134 is configured to transmit at least a portion of the excitation light from the multiple outer optical cores of the CFB 10 towards the peripheral reflector 150. The intervening portion 134 is also configured to transmit at least a portion of the fluorescent light to the multiple inner optical cores of the CFB 10 when the end cap 112 is aligned against the distal end of the CFB 10.

[0082] The curved profile of reflector surface 152 is designed to redirect and focus excitation light output from the multiple outer optical cores of the CFB such that the redirected excitation light forms a light sheet that propagates at least partially across front recess 144 in front of the end face of CFB 10 for excitation of a sample or material within front recess 144 and generation of fluorescence therein. At least a portion of the fluorescent light is coupled into the multiple inner optical cores of CFB 10.

[0083] Those skilled in the art will also appreciate that various modifications are possible to the end caps and any of the end caps described above. For example, the peripheral reflector 50 may not be generally annular, but may extend only partially around the circumference of the front section 44 of the passageway. Similarly, the peripheral reflector 150 may not be generally annular, but may extend only partially around the circumference of the front recess 144.

[0084] The peripheral lens 60 may not be generally annular, but may extend only partially around the front section 44 of the passageway.

[0085] Rather than being formed as two separate pieces that are subsequently mated and attached, the end cap may be one piece. For example, a reflective coating may be applied to the reflector surface 52 of the first portion 12a of the end cap 12, obviating the need for the second portion 12b.

[0086] In a variation of the end cap 12 of FIG. 2, the end cap can have an intervening portion configured to extend across a passage in front of the end face of the CFB 10 at the distal end of the CFB 10 when the end cap 12 is aligned relative to the distal end of the CFB 10 to define a front recess for receiving a sample or material to be imaged on the front side of the intervening portion and a rear recess for receiving the distal end of the CFB 10.

[0087] In a variation of the end cap 112 of FIG. 10, the end cap may not have an intervening portion such as the intervening portion 134 extending between the front recess 144 and the rear recess 140. Instead, the end cap may define a passageway extending from the rear side of the end cap to the front side of the end cap. The passageway may include a rear space in the form of a wider diameter rear section extending from the rear side of the end cap and configured to receive the distal end of the CFB 10. The passageway may include a sample space in the form of a narrower diameter front section extending from the front side of the end cap and configured to receive the sample or material to be imaged. As a result, when the distal end of the CFB 10 is inserted into the wider diameter rear section of the passageway, the distal end face 10a of the CFB 10 cannot protrude axially into the narrower diameter front section of the passageway. The end cap may be generally annular.

[0088] Although each of the end caps 12, 112 are described above as being configured for use with a PMMA CFB, the end caps may be configured for use with a coherent fiber bundle (CFB) that includes or is formed from any type of polymer material, or the end caps may be configured for use with a CFB that includes or is formed from a glass material.

[0089] The end cap 12 can be configured such that when the end cap 12 is aligned with respect to the distal end of the CFB 10, the peripheral reflector 50 redirects excitation light output from the multiple outer optical cores of the CFB 10 such that the redirected excitation light propagates at least partially across the front section 44 of the passage in front of the end face of the CFB 10 for excitation of a sample or material within the front section 44 of the passage and generation of Raman scattered light therein, and at least a portion of the Raman scattered light is coupled into the multiple inner optical cores of the CFB 10. Similarly, the end cap 112 can be configured such that when the end cap 112 is aligned with respect to the distal end of the CFB 10, the peripheral reflector 150 redirects excitation light output from the multiple outer optical cores of the CFB 10 such that the redirected excitation light propagates at least partially across the front recess 144 in front of the end face of the CFB 10 for excitation of a sample or material within the front recess 144 and generation of Raman scattered light therein, with at least a portion of the Raman scattered light being coupled into the multiple inner optical cores of the CFB 10. Such an end cap can be used for SPIM imaging of the Raman scattered light.

[0090] As mentioned above, the present disclosure has been described with respect to preferred embodiments, but it should be understood that these embodiments are merely examples and the claims are not limited to these embodiments. Those skilled in the art may make modifications and substitutions to the described embodiments in light of the present disclosure that are considered to fall within the scope of the appended claims. Each feature disclosed or illustrated herein may be incorporated into any embodiment alone or in any suitable combination with any other feature disclosed or illustrated herein. In particular, those skilled in the art will understand that one or more of the features of the embodiments of the present disclosure described above with reference to the drawings may provide effects or advantages when used separately from one or more of the other features of the embodiments of the present disclosure, and that other combinations of features are possible other than the specific combinations of features of the embodiments of the present disclosure described above.

[0091] Those skilled in the art will appreciate that in the foregoing description and in the appended claims, positional terms such as "on," "along," "beside," and the like are made with reference to conceptual diagrams such as those shown in the accompanying drawings. These terms are used for ease of reference but are not intended to be limiting in nature. Thus, these terms should be understood to refer to objects when in the orientation shown in the accompanying drawings.

[0092] The use of the term "comprising" when used in connection with features of an embodiment of the present disclosure does not exclude other features or steps. The use of the terms "a" or "an" when used in connection with features of an embodiment of the present disclosure does not exclude the possibility that the embodiment may include a plurality of such features.

[0093] The use of reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

1. An end cap for a coherent fiber bundle (CFB) to enable selective planar illumination microscopy (SPIM), One or more CFB alignment mechanisms for aligning the end cap with respect to the distal end of the CFB, A sample space for receiving a sample or material to be imaged, wherein the sample space extends from the front side of the end cap, A peripheral reflector is at least partially positioned around the sample space. Equipped with, The end cap is configured such that when the end cap is aligned with the distal end of the CFB, the peripheral reflector redirects excitation light emitted from a plurality of outer optical cores of the CFB, and as a result, the redirected excitation light propagates at least partially across the sample space in front of the end face of the CFB for excitation of the sample or material in the sample space and generation of fluorescence in the sample space, and at least a portion of the fluorescence is coupled to a plurality of inner optical cores of the CFB.

2. The end cap according to claim 1, wherein the peripheral reflector is annular or substantially annular.

3. The end cap according to claim 1, wherein the peripheral reflector defines a reflector surface that extends at least partially around the sample space.

4. The end cap according to claim 3, wherein the end cap defines a longitudinal axis for alignment with the longitudinal axis of the CFB, and the normal of the reflector surface extends along a direction having a radially outward component with respect to the longitudinal axis of the end cap.

5. The end cap according to claim 4, wherein the reflector surface has a linear or curved contour when viewed in a longitudinal cross-section of the end cap that includes the longitudinal axis of the end cap.

6. The end cap according to claim 5, wherein the curved contour of the reflector surface is convex outward with respect to the longitudinal axis of the end cap.

7. The end cap according to claim 4, comprising a peripheral lens at least partially positioned around the sample space and radially positioned between the peripheral reflector and the sample space with respect to the longitudinal axis, wherein the peripheral lens is configured to concentrate or focus the redirected excitation light when the redirected excitation light propagates at least partially across the sample space in front of the end face of the CFB toward the longitudinal axis of the end cap.

8. The end cap according to claim 7, wherein the peripheral lens defines the outline of a lens that is convex inward with respect to the longitudinal axis of the end cap.

9. The end cap according to claim 7, wherein the peripheral lens defines the sample space at least partially.

10. The end cap according to claim 7, wherein the peripheral lens is annular or substantially annular.

11. The end cap according to claim 3, wherein the end cap defines a longitudinal axis for alignment with the longitudinal axis of the CFB, and the normal of the reflector surface extends along a direction having a component radially inward with respect to the longitudinal axis of the end cap.

12. The end cap according to claim 11, wherein the reflector surface has a linear or curved contour when viewed in a longitudinal cross-section of the end cap that includes the longitudinal axis of the end cap.

13. The end cap according to claim 12, wherein the curved contour of the reflector surface is concave inward with respect to the longitudinal axis of the end cap.

14. The end cap according to claim 3, wherein the peripheral reflector includes a reflective material or coating formed on the reflector surface, disposed on the reflector surface, or covering the reflector surface.

15. The end cap according to claim 1, wherein the one or more CFB alignment mechanisms include a rear space for receiving the distal end of the CFB, and the rear space extends from the rear side of the end cap.

16. The end cap according to claim 1, wherein the end cap comprises an intervening portion configured to extend between the sample space and the end face of the CFB at the distal end of the CFB when the end cap is aligned with the distal end of the CFB.

17. The end cap according to claim 1, wherein the end cap is integral with the end cap.

18. The end cap according to claim 1, wherein the end cap comprises a first and a second portion, and the first and second portions comprise one or more complementary alignment mechanisms for aligning the first and second portions with respect to each other.

19. The end cap according to claim 18, wherein the first portion defines one or more CFB alignment mechanisms, the first and second portions together define the peripheral reflector, optionally the first portion defines the reflector surface of the one or more CFB alignment mechanisms and the peripheral reflector, and the second portion defines a reflective material or coating that covers the reflector surface when the first and second portions are aligned.

20. The end cap according to claim 18, wherein the first portion defines one or more CFB alignment mechanisms, and the second portion defines the peripheral reflector.

21. The end cap according to claim 1, wherein the end cap contains a polymer material such as PMMA, or is configured to be used with a coherent fiber bundle (CFB) formed from a polymer material, or the end cap contains a glass material, or is configured to be used with a coherent fiber bundle (CFB) formed from a glass material.

22. The end cap according to claim 1, wherein when the end cap is aligned with the distal end of the CFB, the peripheral reflector is configured to redirect excitation light output from the plurality of outer optical cores of the CFB, so that the redirected excitation light propagates at least partially across the sample space in front of the end face of the CFB for excitation of the sample or material in the sample space and generation of Raman scattered light in the sample space, and at least a portion of the Raman scattered light is coupled to the plurality of inner optical cores of the CFB.

23. The end cap according to claim 1, wherein the end cap contains fused silica or is formed from fused silica.

24. A coherent fiber bundle (CFB) assembly for SPIM, comprising a coherent fiber bundle (CFB) and an end cap according to any one of claims 1 to 23 attached to the distal end of the CFB.

25. The coherent fiber bundle (CFB) assembly according to claim 24, wherein the coherent fiber bundle (CFB) comprises or is formed from a polymer material such as PMMA, or the coherent fiber bundle (CFB) comprises or is formed from a glass material.

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