OCT catheter with low refractive index optical material

Abstract

Embodiments of the present disclosure include devices, systems, and methods for catheters with a single element for both imaging and intervention. The catheter may have a distal tip that is positionable within a patient (e.g., within the lumen of a vessel). The distal tip may have optical components that include both a reflective surface and a tapered distal end. The reflective surface may redirect light (e.g., light received along the catheter's optical fiber) into an imaging beam, which may be directed toward the vessel wall. The tapered distal end may be a crossing tool used to cross an occluded or partially occluded segment of a vessel. In some embodiments, the reflective surface and the tapered distal end may be the same surface of the optical component. A low refractive index optical filler may be provided to reduce image artifacts at the imaging interface with the patient's fluids and tissues.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to the benefit of U.S. Provisional Application No. 63 / 165,672, filed March 24, 2021, and U.S. Provisional Application No. 63 / 014,110, filed April 22, 2020, which are incorporated by reference in their entireties. This application is also related to U.S. Provisional Application No. 63 / 165,673, filed March 24, 2021, which is incorporated by reference in its entirety.

[0002] FIELD OF THE INVENTION Embodiments herein relate generally to intravascular imaging, total occlusion crossing, and atherectomy devices, and more particularly to an interferometric imaging device, imaging and intervention system, and method of operation with a single element for intervention and imaging. [Background technology]

[0003] Minimally invasive interventions have consistently been shown to be as effective or more effective than traditional open surgical interventions and result in lower mortality rates. For many such minimally invasive procedures, the ability to accurately track the positioning of instruments inserted into a patient's vascular system is of paramount importance to surgeons and other medical personnel performing such interventions. The majority of minimally invasive procedures involve the use of flexible guidewires and catheters that are directed to the target vascular site using the guidewire. However, steering the guidewire to the target vascular site can be difficult and risky. For example, an improperly steered guidewire can cause harmful vessel dissection, perforation, or thrombosis. While some of these risks can be eliminated by heparinization, the increased use of such anticoagulants can increase the risk of intraoperative bleeding.

[0004] Additionally, most guidewire navigation is currently performed under x-ray fluoroscopic imaging, which often requires the surgeon or other medical personnel to be exposed to prolonged radiation.

[0005] Therefore, improved devices, systems, and methods for intravascular imaging are needed that address the challenges faced by current devices on the market. Such solutions should reduce the risk of complications for the patient and reduce the risk of radiation exposure for the operator. Furthermore, such solutions should be compatible or easily adapted for use with other minimally invasive surgical devices, such as atherectomy catheters. Furthermore, such solutions should reduce the complexity of current devices and be cost-effective to manufacture. Intravascular imaging devices, systems, and methods may also be configured to improve imaging quality and / or reduce various image artifacts. Summary of the Invention [Means for solving the problem]

[0006] Embodiments of the present disclosure are directed to apparatus, systems, and methods for a catheter, guidewire, or interventional device with a single-element tip for both imaging and intervention. The catheter may have a distal tip that is positionable within a patient (e.g., within the lumen of a vessel). The distal tip may have a component or block that includes both optical and mechanical features for inserting through and / or across an atherosclerotic plaque. The optical feature may redirect light (e.g., light received along the catheter's optical fiber) into an imaging beam, which may be directed toward the vessel wall, while the mechanical feature is configured to facilitate crossing of an occluded or partially occluded segment of the vessel via the angled tip. The imaging component or assembly may also be configured to reduce one or more imaging artifacts.

[0007] In one embodiment, an imaging device is provided, comprising: an outer shaft with a lumen; an optical fiber located within the lumen of the outer shaft; a reflective element disposed within the lumen of the outer shaft, the reflective element comprising an optical material with an angled surface configured with respect to the imaging beam; and a first optical filler between the distal end of the optical fiber and the reflective element, the first optical filler having a refractive index less than 1.40. The refractive index of the first optical filler may be within a range of 1.30 to 1.40 or 1.33 to 1.38. The optical filler may comprise an aliphatic urethane acrylate and an acrylic monomer. The aliphatic urethane acrylate percentage may be 30% to 70% and the acrylic monomer may be 70% to 30%, or the aliphatic urethane acrylate percentage may be 40% to 65% and the acrylic monomer may be 60% to 35%. The viscosity of the first optical filler may be in the range of 1,000 to 3,000 cps, 1,500 to 3,000 cps, or 2,000 to 2,500 cps. The imaging device of claim 1 further includes a lens positioned between the optical fiber and the reflective element. The lens may be a Fresnel lens, a GRIN lens, a plano-convex lens, or a bi-convex lens. The lens may be tilted at an angle of 0.1 to 2.0 degrees. The imaging device may further include an uncladded fiber followed by a GRIN lens between the optical fiber and the reflective element. The first optical filler may be positioned between the lens and the reflective element. The imaging device may further include a second optical filler positioned between the optical fiber and the lens. The first optical filler and the second optical filler may comprise different materials or may comprise the same components but in different ratios, and both the first and second optical fillers have refractive indices less than 1.50. The angled surface of the reflective element may include a Fresnel diffraction pattern. The Fresnel diffraction pattern may have a variable degree of collimating or focusing power along its major axis, minor axis, and between its major and minor axes. The imaging device may further include a lens positioned between the optical fiber and the reflective element. The lens may be a GRIN lens.The first optical filler may be located between the lens and the reflective element. The reflective element may further include a tapered distal end protruding from the lumen of the outer shaft, the tapered distal end configured to penetrate tissue. The first optical filler may include a UV-cured optical material. The collimating lens may be located between the optical fiber and the first optical filler. The collimating lens may be a GRIN lens, and may be a plano-convex, bi-convex, or Fresnel lens.

[0008] In another embodiment, an imaging device is provided, comprising: an outer shaft with a lumen; an optical fiber located within the lumen of the outer shaft; a reflective element disposed within the lumen of the outer shaft, the reflective element comprising an optical material with an angled surface configured with respect to the imaging beam; a beam-collimating element between the optical fiber and a first optical filler; and a first optical filler between a distal end of the beam-collimating element and the reflective element, the first optical filler having a refractive index less than 1.40. The interface between the beam-collimating element and the first optical filler has a reflection loss or reference signal of -15 dB to -28 dB, -20 dB to -35 dB, or -23 dB to -40 dB. The beam-collimating element may be a Fresnel lens or a GRIN lens.

[0009] In yet another embodiment, an imaging device is provided, comprising: an outer shaft with a lumen; an optical fiber located within the lumen of the outer shaft; a reflective element disposed within the lumen of the outer shaft, the reflective element comprising an optical material with an angled surface configured with respect to the imaging beam; a beam-collimating section between the optical fiber and a first optical filler, the beam-collimating section consisting of an unclad fiber and a GRIN lens; and a first optical filler between a distal end of the GRIN lens and the reflective element, the first optical filler having a refractive index less than 1.40. The interface between the beam-collimating element and the first optical filler may have a reflection loss or reference signal of -15 dB to -28 dB, -20 dB to -35 dB, or -23 dB to -40 dB. The interface between the optical fiber and the unclad fiber and the interface between the unclad fiber and the GRIN lens may have a reflection artifact weaker than -40 dB.

[0010] In another variation, an imaging device is provided, comprising: an outer shaft with a lumen; an optical fiber located within the lumen of the outer shaft; a reflective element disposed within the lumen of the outer shaft, the reflective element comprising an optical material with an angled surface configured with respect to the imaging beam; a beam-collimating section between the optical fiber and the first optical filler and comprising a GRIN lens; and a first optical filler between a distal end of the GRIN lens and the reflective element, the first optical filler having a refractive index less than 1.40. The interface between the beam-collimating element and the first optical filler may have a reflection loss or reference signal of -15 dB to -28 dB, -20 dB to -35 dB, or -23 dB to -40 dB.

[0011] In yet another variation, an imaging device is provided, comprising: an outer shaft with a lumen; an optical fiber located within the lumen of the outer shaft; a reflective element disposed within the lumen of the outer shaft, the reflective element comprising a diffraction pattern on a flat surface of an optical material with an angled surface configured with respect to the imaging beam; and a first optical filler between the optical fiber and the reflective element, the first optical filler having a refractive index less than 1.40. The imaging device may further comprise a lens located between the optical fiber and the reflective element. The lens may be a Fresnel lens, a plano-convex lens, or a bi-convex lens. The lens may be tilted by 0.1 to 2.0 degrees. The lens may be a GRIN lens. The lens may comprise an unclad fiber followed by a GRIN lens.

[0012] In another embodiment, an imaging device is provided, comprising: an outer shaft with a lumen; an optical fiber located within the lumen of the outer shaft; a reflective element disposed within the lumen of the outer shaft, the reflective element comprising a diffraction pattern on a planar surface with an angled surface configured for an imaging beam and having a variable degree of collimation and focusing power between its major and minor axes; and a first optical filler between the optical fiber and the reflective element, the first optical filler having a refractive index less than 1.40. The imaging device may further comprise a lens located between the optical fiber and the reflective element. The lens may be a Fresnel lens, a plano-convex lens, or a bi-convex lens. The lens may be tilted by 0.1 to 2.0 degrees. The lens may also be a GRIN lens, or comprise an uncladded fiber followed by a GRIN lens.

[0013] In another embodiment, an imaging device is provided that includes an optical fiber, a reflective element with an angled surface configured with respect to an imaging beam, a beam-collimating GRIN lens having a pitch of at least 0.75 or greater within a unit length, and a first optical filler between the distal surface of the GRIN lens and the reflective element, the first optical filler having a refractive index less than 1.40. The interface between the optical fiber and the GRIN lens produces a reflection artifact that is stronger or weaker than -40 dB.

[0014] In yet another embodiment, an imaging device is provided that includes an optical fiber, a reflective element with an angled surface configured with respect to an imaging beam, and a beam-collimating GRIN lens having a pitch of at least 0.75 or greater within a unit length, the beam-collimating GRIN lens having a reflection artifact stronger than -40 dB at the interface between the optical fiber and the GRIN lens, and a first optical filler between the distal surface of the GRIN lens and the reflective element, the first optical filler having a refractive index less than 1.40.

[0015] In yet another embodiment, an imaging device is provided comprising: an outer shaft with a lumen; an optical fiber located within the lumen of the outer shaft; a reflective element disposed within the lumen of the outer shaft, the reflective element comprising a diffraction pattern on a planar surface having a variable degree of collimating and focusing power between its major and minor axes with an angled surface configured with respect to the imaging beam; a beam collimating element between the optical fiber and the first optical filling material; and a first optical filling material between the distal end of the beam collimating element and the reflective element, the first optical filling material having a refractive index less than 1.40. The present invention provides, for example, the following. (Item 1) An imaging device, an outer shaft with a lumen; an optical fiber located within a lumen of the outer shaft; a reflective element disposed within a lumen of the outer shaft, the reflective element comprising an optical material with an angled surface configured with respect to an imaging beam; a first optical filler between the distal end of the optical fiber and the reflective element, the first optical filler having a refractive index less than 1.40; and An imaging device comprising: (Item 2) Item 1. The imaging device according to item 1, wherein the refractive index of the first optical filler is within a range of 1.30 to 1.40. (Item 3) Item 1. The imaging device according to item 1, wherein the refractive index of the first optical filler is within a range of 1.33 to 1.38. (Item 4) Item 10. The imaging device of item 1, wherein the first optical filler comprises an aliphatic urethane acrylate and an acrylic monomer. (Item 5) 5. The imaging device according to item 4, wherein the aliphatic urethane acrylate percentage is 30% to 70%, and the acrylic monomer percentage is 70% to 30%. (Item 6) 6. The imaging device according to item 5, wherein the aliphatic urethane acrylate percentage is 40% to 65%, and the acrylic monomer percentage is 60% to 35%. (Item 7) 5. The imaging device according to item 4, wherein the viscosity of the first optical filler is in the range of 1,000 to 3,000 cps. (Item 8) 8. The imaging device according to item 7, wherein the viscosity of the first optical filler is in the range of 1,500 to 3,000 cps. (Item 9) 8. The imaging device according to item 7, wherein the viscosity of the first optical filler is in the range of 2,000 to 2,500 cps. (Item 10) Item 10. The imaging device of item 1, further comprising a lens positioned between the optical fiber and the reflective element. (Item 11) Item 11. The imaging device of item 10, wherein the lens is a Fresnel lens. (Item 12) Item 11. The imaging device of item 10, wherein the lens is a plano-convex or biconvex lens. (Item 13) Item 11. The imaging device according to item 10, wherein the lens is tilted at an angle of 0.1 to 2.0 degrees. (Item 14) Item 11. The imaging device of item 10, wherein the lens is a GRIN lens. (Item 15) Item 14. The imaging device of item 1, further comprising a no-cladding fiber followed by a GRIN lens between the optical fiber and the reflective element. (Item 16) Item 11. The imaging device of item 10, wherein the first optical filler is further located between the lens and the reflective element. (Item 17) Item 11. The imaging device of item 10, further comprising a second optical filler positioned between the optical fiber and the lens. (Item 18) Item 18. The imaging device of item 17, wherein the first optical filler and the second optical filler comprise different materials. (Item 19) Item 18. The imaging device of item 17, wherein the first and second optical fillers comprise components that are the same but in different proportions, and both the first and second optical fillers have a refractive index less than 1.50. (Item 20) Item 10. The imaging device of item 1, wherein the angled surface of the reflective element comprises a Fresnel diffraction pattern. (Item 21) 21. The imaging device of claim 20, wherein the Fresnel diffraction pattern has a variable degree of collimating or focusing power along its major axis, minor axis, and between the major and minor axes. (Item 22) 21. The imaging device of claim 20, further comprising a lens positioned between the optical fiber and the reflective element. (Item 23) Item 23. The imaging device of item 22, wherein the lens is a GRIN lens. (Item 24) Item 23. The imaging device of item 22, wherein the first optical filler is located between the lens and the reflective element. (Item 25) Item 10. The imaging device of item 1, wherein the reflective element further comprises a tapered distal end protruding from the lumen of the outer shaft, the tapered distal end configured to penetrate tissue. (Item 26) Item 10. The imaging device of item 1, wherein the first optical filler comprises a UV-cured optical material. (Item 27) Item 1, wherein a collimating lens is located between the optical fiber and the first optical filling material. (Item 28) Item 18. The imaging device of item 17, wherein the collimating lens is a GRIN lens and a plano-convex, or bi-convex or Fresnel lens. (Item 29) An imaging device, an outer shaft with a lumen; an optical fiber located within a lumen of the outer shaft; a reflective element disposed within a lumen of the outer shaft, the reflective element comprising an optical material with an angled surface configured with respect to an imaging beam; a beam collimating element between the optical fiber and a first optical filling material; a first optical filler between the distal end of the beam-collimating element and the reflective element, the first optical filler having a refractive index less than 1.40; and An imaging device comprising: (Item 30) 30. The imaging device of item 29, wherein the interface between the beam collimating element and the first optical filling material has a reflection loss or reference signal of −15 dB to −28 dB. (Item 31) 30. The imaging device of item 29, wherein the interface between the beam collimating element and the first optical filling material has a reflection loss or reference signal of −20 dB to −35 dB. (Item 32) 30. The imaging device of item 29, wherein the interface between the beam collimating element and the first optical filling material has a reflection loss or reference signal of −23 dB to −40 dB. (Item 33) 30. The imaging device of item 29, wherein the beam collimating element is a Fresnel lens. (Item 34) 30. The imaging device of item 29, wherein the beam collimating element is a GRIN lens. (Item 35) An imaging device, an outer shaft with a lumen; an optical fiber located within a lumen of the outer shaft; a reflective element disposed within a lumen of the outer shaft, the reflective element comprising an optical material with an angled surface configured with respect to an imaging beam; a beam collimating section between the optical fiber and the first optical filling material, the beam collimating section comprising an uncladded fiber and a GRIN lens; a first optical filler between the distal end of the GRIN lens and the reflective element, the first optical filler having a refractive index less than 1.40; and An imaging device comprising: (Item 36) Item 36. The imaging device of item 35, wherein the interface between the beam collimating element and the first optical filling material has a reflection loss or reference signal of −15 dB to −28 dB. (Item 37) Item 36. The imaging device of item 35, wherein the interface between the beam collimating element and the first optical filling material has a reflection loss or reference signal of −20 dB to −35 dB. (Item 38) Item 36. The imaging device of item 35, wherein the interface between the beam collimating element and the first optical filling material has a reflection loss or reference signal of −23 dB to −40 dB. (Item 39) Item 36. The imaging device of item 35, wherein the interface between the optical fiber and the unclad fiber and the interface between the unclad fiber and the GRIN lens produce reflection artifacts weaker than −40 dB. (Item 40) An imaging device, an outer shaft with a lumen; an optical fiber located within a lumen of the outer shaft; a reflective element disposed within a lumen of the outer shaft, the reflective element comprising an optical material with an angled surface configured with respect to an imaging beam; a beam collimating section between the optical fiber and the first optical filling material, the beam collimating section being made of a GRIN lens; a first optical filler between the distal end of the GRIN lens and the reflective element, the first optical filler having a refractive index less than 1.40; and An imaging device comprising: (Item 41) Item 41. The imaging device of item 40, wherein the interface between the beam collimating element and the first optical filling material produces a reflection loss or reference signal of −15 dB to −28 dB. (Item 42) Item 41. The imaging device of item 40, wherein the interface between the beam collimating element and the first optical filling material produces a reflection loss or reference signal of −20 dB to −35 dB. (Item 43) Item 41. The imaging device of item 40, wherein the interface between the beam collimating element and the first optical filling material produces a reflection loss or reference signal of −23 dB to −40 dB. (Item 44) An imaging device, an outer shaft with a lumen; an optical fiber located within a lumen of the outer shaft; a reflective element disposed within a lumen of the outer shaft, the reflective element comprising a diffractive pattern on a flat surface of an optical material with an angled surface configured with respect to an imaging beam; a first optical filler between the optical fiber and the reflective element, the first optical filler having a refractive index less than 1.40; and An imaging device comprising: (Item 45) Item 45. The imaging device of item 44, further comprising a lens positioned between the optical fiber and the reflective element. (Item 46) Item 45. The imaging device of item 44, wherein the lens is a Fresnel lens. (Item 47) Item 45. The imaging device of item 44, wherein the lens is a plano-convex or biconvex lens. (Item 48) Item 48. The imaging device according to item 47, wherein the lens is tilted at an angle of 0.1 to 2.0 degrees. (Item 49) Item 45. The imaging device of item 44, wherein the lens is a GRIN lens. (Item 50) Item 45. The imaging device of item 44, wherein the lens comprises an uncladded fiber followed by a GRIN lens. (Item 51) An imaging device, an outer shaft with a lumen; an optical fiber located within a lumen of the outer shaft; a reflective element disposed within a lumen of the outer shaft, the reflective element comprising a diffraction pattern on a planar surface having a variable degree of collimating and focusing power between its major and minor axes with an angled surface configured with respect to the imaging beam; a first optical filler between the optical fiber and the reflective element, the first optical filler having a refractive index less than 1.40; and An imaging device comprising: (Item 52) Item 52. The imaging device of item 51, further comprising a lens positioned between the optical fiber and the reflective element. (Item 53) Item 52. The imaging device of item 51, wherein the lens is a Fresnel lens. (Item 54) Item 52. The imaging device of item 51, wherein the lens is a plano-convex or biconvex lens. (Item 55) Item 55. The imaging device according to item 54, wherein the lens is tilted at an angle of 0.1 to 2.0 degrees. (Item 56) Item 52. The imaging device of item 51, wherein the lens is a GRIN lens. (Item 57) Item 52. The imaging device of item 51, wherein the lens comprises an uncladded fiber followed by a GRIN lens. (Item 58) An imaging device, An optical fiber; a reflective element with an angled surface configured with respect to the imaging beam; a beam-collimating GRIN lens having a pitch of at least 0.75 or greater within a unit length; a first optical filler between the distal surface of the GRIN lens and the reflective element, the first optical filler having a refractive index less than 1.40; and An imaging device comprising: (Item 59) Item 59. The imaging device of item 58, wherein the interface between the optical fiber and the GRIN lens produces a reflection artifact stronger than −40 dB. (Item 60) Item 59. The imaging device of item 58, wherein the interface between the optical fiber and the GRIN lens produces reflection artifacts weaker than −40 dB. (Item 61) An imaging device, An optical fiber; a reflective element with an angled surface configured with respect to the imaging beam; a beam-collimating GRIN lens having a pitch of at least 0.75 or greater within a unit length, the beam-collimating GRIN lens having a reflection artifact of greater than -40 dB at an interface between the optical fiber and the GRIN lens; a first optical filler between the distal surface of the GRIN lens and the reflective element, the first optical filler having a refractive index less than 1.40; and An imaging device comprising: (Item 62) An imaging device, an outer shaft with a lumen; an optical fiber located within a lumen of the outer shaft; a reflective element disposed within a lumen of the outer shaft, the reflective element comprising a diffraction pattern on a planar surface having a variable degree of collimating and focusing power between its major and minor axes with an angled surface configured with respect to the imaging beam; a beam collimating element between the optical fiber and a first optical filling material; a first optical filler between the distal end of the beam-collimating element and the reflective element, the first optical filler having a refractive index less than 1.40; and An imaging device comprising: [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of an imaging and intervention system according to some embodiments of the present disclosure.

[0017] [Figure 2] FIG. 2 is a cross-sectional view of a distal end of an imaging crossing device according to some embodiments of the present disclosure.

[0018] [Figure 3] FIG. 3 is a cross-sectional view of the distal end of another embodiment of an exemplary imaging crossing device.

[0019] [Figure 4] FIG. 4 is a cross-sectional view of the distal end of another embodiment of an imaging crossing device.

[0020] [Figure 5] 5A and 5B are schematic diagrams of an exemplary imaging crossing device with an angled tip.

[0021] [Figure 6A] 6A and 6B are schematic cross-sectional and perspective views of another exemplary imaging cross device. [Figure 6B]6A and 6B are schematic cross-sectional and perspective views of another exemplary imaging cross device.

[0022] [Figure 7-1] 7A-7E are side elevation, side perspective, rear perspective, front perspective, and top perspective views, respectively, of the optical element in FIGS. 6A and 6B. [Figure 7-2] 7A-7E are side elevation, side perspective, rear perspective, front perspective, and top perspective views, respectively, of the optical element in FIGS. 6A and 6B.

[0023] [Figure 8-1] 8A and 8B are schematic perspective and side views of the imaging cross device in FIGS. 6A and 6B in a retracted position, and FIGS. 8C and 8D are schematic perspective and side views of the imaging cross device in an extended position. [Figure 8-2] 8A and 8B are schematic perspective and side views of the imaging cross device in FIGS. 6A and 6B in a retracted position, and FIGS. 8C and 8D are schematic perspective and side views of the imaging cross device in an extended position.

[0024] [Figure 9] FIG. 9 is a schematic longitudinal cross-sectional view of another exemplary embodiment of an imaging cross device.

[0025] [Figure 10] FIG. 10 is a schematic longitudinal cross-sectional view of another exemplary embodiment of an imaging cross device.

[0026] [Figure 11] FIG. 11 is a schematic longitudinal cross-sectional view of another exemplary embodiment of an imaging cross device.

[0027] [Figure 12] Figure 12A depicts an exemplary guide catheter configured for use with an imaging crossing device, and Figure 12B is a schematic diagram of the proximal hub and proximal shaft of the guide catheter in Figure 12A.

[0028] [Figure 13] 13 and 14 diagrammatically depict different variations of marker bands that may be provided on a guide catheter. [Figure 14] 13 and 14 diagrammatically depict different variations of marker bands that may be provided on a guide catheter.

[0029] [Figure 15] 15 and 16 are schematic side views of different guide catheter tips that may be used. [Figure 16] 15 and 16 are schematic side views of different guide catheter tips that may be used.

[0030] [Figure 17] 17A and 17B are proximal elevational and perspective views of the guide catheter tip of FIG.

[0031] [Figure 18-1] 18A-18C are OCT images depicting various types of artifacts that can arise from refractive index mismatch between the imaging system and the surrounding fluid and tissue. [Figure 18-2] 18A-18C are OCT images depicting various types of artifacts that can arise from refractive index mismatch between the imaging system and the surrounding fluid and tissue.

[0032] [Figure 19-1] 19A-19C are schematic cross-sectional views of a side-viewing OCT imaging system depicting back-reflection from different optical filler configurations, and Figures 19D and 19E are schematic cross-sectional views of a side-viewing OCT imaging system with optical filler configurations that reduce back-reflection. [Figure 19-2]19A-19C are schematic cross-sectional views of a side-viewing OCT imaging system depicting back-reflection from different optical filler configurations, and Figures 19D and 19E are schematic cross-sectional views of a side-viewing OCT imaging system with optical filler configurations that reduce back-reflection.

[0033] [Figure 20-1] 20A-20C are OCT images with reduced artifacts resulting from low refractive index optical filler material within the imaging system. [Figure 20-2] 20A-20C are OCT images with reduced artifacts resulting from low refractive index optical filler material within the imaging system.

[0034] [Figure 21A] 21A and 21B are schematic cross-sectional views of an OCT imaging system with and without an outer shaft and with a low refractive index optical filler, respectively. [Figure 21B] 21A and 21B are schematic cross-sectional views of an OCT imaging system with and without an outer shaft and with a low refractive index optical filler, respectively.

[0035] [Figure 22-1] 22A and 22B are schematic depictions of variations of OCT imaging assemblies including a GRIN lens with and without a non-cladding fiber section, respectively. 22C and 22D schematically depict an OCT imaging assembly with a GRIN lens configured to produce a collimated beam. 22E and 22F schematically depict an OCT imaging assembly with a GRIN lens configured to produce a focused beam. [Figure 22-2]22A and 22B are schematic depictions of variations of OCT imaging assemblies including a GRIN lens with and without a non-cladding fiber section, respectively. 22C and 22D schematically depict an OCT imaging assembly with a GRIN lens configured to produce a collimated beam. 22E and 22F schematically depict an OCT imaging assembly with a GRIN lens configured to produce a focused beam. [Figure 22-3] 22A and 22B are schematic depictions of variations of OCT imaging assemblies including a GRIN lens with and without a non-cladding fiber section, respectively. 22C and 22D schematically depict an OCT imaging assembly with a GRIN lens configured to produce a collimated beam. 22E and 22F schematically depict an OCT imaging assembly with a GRIN lens configured to produce a focused beam. [Figure 22-4] 22A and 22B are schematic depictions of variations of OCT imaging assemblies including a GRIN lens with and without a non-cladding fiber section, respectively. 22C and 22D schematically depict an OCT imaging assembly with a GRIN lens configured to produce a collimated beam. 22E and 22F schematically depict an OCT imaging assembly with a GRIN lens configured to produce a focused beam.

[0036] [Figure 23] 23A and 23B are schematic illustrations of another variation of an OCT imaging system involving a GRIN lens.

[0037] [Figure 24] FIG. 24 is a schematic illustration of a variation of an OCT imaging system comprising a spherical or aspherical lens with collimated light.

[0038] [Figure 25]FIG. 25 is a schematic illustration of a variation of an OCT imaging system comprising a spherical or aspherical lens with collimated or non-collimated light.

[0039] [Figure 26-1] 26A and 26C schematically depict an exemplary OCT imaging system embodiment with a Fresnel lens, and FIG. 26B is a perspective component view of the Fresnel lens in FIG. 26A. [Figure 26-2] 26A and 26C schematically depict an exemplary OCT imaging system embodiment with a Fresnel lens, and FIG. 26B is a perspective component view of the Fresnel lens in FIG. 26A.

[0040] [Figure 27-1] Figure 27A is a schematic depiction of a Fresnel reflector in an exemplary OCT imaging system. Figures 27B-27E depict various beam profiles of the OCT imaging system in Figure 27A at various focal lengths and their respective equivalent radii of curvature. Figure 27F is a top perspective view of the Fresnel reflector. [Figure 27-2] Figure 27A is a schematic depiction of a Fresnel reflector in an exemplary OCT imaging system. Figures 27B-27E depict various beam profiles of the OCT imaging system in Figure 27A at various focal lengths and their respective equivalent radii of curvature. Figure 27F is a top perspective view of the Fresnel reflector. [Figure 27-3] Figure 27A is a schematic depiction of a Fresnel reflector in an exemplary OCT imaging system. Figures 27B-27E depict various beam profiles of the OCT imaging system in Figure 27A at various focal lengths and their respective equivalent radii of curvature. Figure 27F is a top perspective view of the Fresnel reflector.

[0041] [Figure 28-1]Figure 28A is a schematic illustration of an OCT imaging system with an exemplary GRIN lens and Fresnel reflector. Figures 28B and 28C are schematic side and end views, respectively, of the beam profile of the OCT imaging system of Figure 28A. Figure 28D depicts the beam profile of the OCT imaging system of Figure 28A. [Figure 28-2] Figure 28A is a schematic illustration of an OCT imaging system with an exemplary GRIN lens and Fresnel reflector. Figures 28B and 28C are schematic side and end views, respectively, of the beam profile of the OCT imaging system of Figure 28A. Figure 28D depicts the beam profile of the OCT imaging system of Figure 28A.

[0042] [Figure 29] 29A and 29B diagrammatically depict the mechanical coupling of an optical fiber and a GRIN lens. DETAILED DESCRIPTION OF THE INVENTION

[0043] Detailed Description The following description of certain embodiments is merely exemplary in nature and is not intended to limit in any way the scope of the present disclosure or its application or uses. In the following detailed description of embodiments of the present systems and methods, references are made to the accompanying drawings, which form a part of this specification and which show, by way of illustration, specific embodiments in which the systems and methods described therein may be practiced. Although these embodiments have been described in sufficient detail to enable those skilled in the art to practice the systems and methods of the present disclosure, it should be understood that other embodiments may be utilized and structural and logical changes may be made without departing from the spirit and scope of the present disclosure. Moreover, for purposes of clarity, detailed descriptions of certain features will not be discussed where they would be apparent to those skilled in the art, so as not to obscure the description of the embodiments of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined only by the appended claims.

[0044] Minimally invasive medical interventions may involve the insertion of a catheter through the lumen of one or more vasculature of a patient. For example, during an atherectomy, a catheter or guidewire is advanced through the patient's blood vessels, and one or more interventional tools may be inserted into the working lumen of the catheter or over the guidewire to remove (or otherwise reduce the volume of) atherosclerotic plaque. In some variations, the progress of catheter advancement through the patient may be monitored, for example, to reduce the risk of puncture or dissection of the vessel wall and / or to monitor the progress of plaque or clot removal.

[0045] The imaging device includes an optical assembly or element that enables imaging of the wall of the vessel in which the imaging device is disposed. Generally, the imaging device may be coupled to an optical system, which may direct light along the imaging device (e.g., along one or more optical fibers of the imaging device). A reflective surface may be located at a distal region of the imaging device and may redirect light to illuminate the vessel lumen and wall. The reflective surface may also redirect light received from the vessel lumen and wall back along the imaging device to the optical system. For example, the imaging device may be an interferometric imaging device that performs optical coherence tomography (OCT) by scanning light along the vessel wall, combining light reflected (or scattered) from the vessel wall with light reflected from a reference surface to generate an interference pattern, and imaging the vessel wall based on the interference pattern. The imaging device may also be configured with an angled or tapered geometry to facilitate crossing of the occluded vasculature. The interventional feature and the reflective surface may be integrated together. It may be useful to reduce the size and bulk of an imaging device and increase its ability to navigate through relatively narrow or occluded vessels. This may be achieved, for example, using optical structures including reflective surfaces and angled or tapered surfaces for crossing occlusions.

[0046] The present disclosure is directed to an interferometric imaging device, imaging and intervention system, and method of operation with a single element for intervention and imaging. The interferometric imaging device includes an optical component at the distal end of the imaging device. The optical component includes both an imaging feature and a crossing element. For example, the imaging feature may be a reflective surface of the optical component at an angle to the long axis of the imaging device to redirect light between the long axis of the imaging device and a side surface of the imaging device. The optical component may also include a geometric configuration, such as an angled, tapered, cutting, or penetrating surface, to facilitate crossing or navigation through plaque, occlusion, or clot as the imaging device passes along a vessel. The mechanical geometry may also be configured with a tissue-contacting surface to penetrate, cut, or abrade plaque. The tissue-contacting surface of the optical component may be adjustably extendable from one end or portion of the imaging device. In some embodiments, the tissue-contacting surface forming the tapered distal end and the reflective surface forming the reflective surface may be the same surface of the optical component.

[0047] For example, the distal tip component may be a monolithic, optically transparent component or structure in which the optical feature is an angled internal reflective surface of the distal geometry region of the structure. The structure may also comprise a tapered geometry to facilitate selective penetration and passage through occluded portions of the vasculature, with the distal geometry region of the structure comprising an angled external surface corresponding to the angled internal reflective surface. Corresponding internal and external points, surfaces, or regions on the structure may be opposing internal and external geometries, parallel internal and external geometries, and / or directly orthogonal or normal internal and external points, surfaces, or regions. The distal geometry region and / or other surfaces of the structure may comprise a coating to enhance the reflectivity or other optical properties of the structure.

[0048] 1 is a schematic diagram of an imaging and intervention system according to some embodiments of the present disclosure. The imaging system 100 includes a guidewire, catheter, or imaging device 102, all or part of which may be inserted into a patient. A distal tip 104 of the imaging device 102 may be used for imaging the patient's tissues and / or for performing one or more interventions within the patient. A proximal end of the imaging device 102 is coupled to a control unit 110, which may be used to perform the imaging and / or interventions through the imaging device 102. An optional computing device 130 may be coupled to the control unit 110 to operate or interface with the control unit 110, feed imaging data back to the control unit 110 from the optical unit and human interface device / position unit, and / or record / store / interpret / augment data generated by the control unit 110 (e.g., imaging data). The control unit 110 may optionally comprise a graphical processing unit and use neural networks to enhance the data received from the optical unit and human interface device / position unit to improve visualization and image guidance for the physician through the display 136.

[0049] The inset of FIG. 1 depicts an expanded schematic view of the distal tip 104 of the imaging device 102. The imaging device 102 includes an outer shaft 108 and an inner member 105 that includes an optical component 106. The optical component 106 includes a reflective surface that is used to image tissue 107 surrounding the distal tip 104 of the imaging device 102 and a tapered distal end that may be used to perform one or more interventions. For example, the optical component 106 may include a crossing element for crossing a stenosis or obstruction within a vessel, such as a complete or partial occlusion 109. The tissue 107 may be the wall of a vessel within which the distal tip 104 is positioned. For example, the tissue 107 may be the wall of a coronary artery vessel.

[0050] The control unit 110 includes a position unit 120 and an optical unit 112. While shown as a single control unit 110 in the example of FIG. 1 , it should be understood that the human interface device / position unit 120 and the optical unit 110 may be separate components of the system 100 in some embodiments. The human interface device / position unit 120 may be used to control and / or track the position of the imaging device 102 and / or one or more components of the imaging device 102 relative to the imaging device 102. The optical unit 110 may image the tissue 107 surrounding the distal tip 104 by providing light and receiving light through the imaging device.

[0051] The optical unit 112 may be used to perform optical coherence tomography (OCT). The optical unit 112 includes a light source 116, which provides the transmitted light Tx. The light source 116 may be a laser, a light-emitting diode (LED), an arc lamp, an incandescent source, a fluorescent source, other light sources, or a combination thereof. The transmitted light Tx may have a relatively narrow bandwidth centered on a particular frequency, may be a broadband source (e.g., white light), or may be a combination thereof. In some embodiments, the light source 116 may be a swept laser, and the center frequency of the transmitted light Tx may vary over time. In some embodiments, the center frequency of the transmitted light may be selected to be transparent to tissue. For example, the center frequency may be in the near-infrared (NIR) window, where tissue has relatively low extinction (e.g., between about 800 nm and 1,400 nm).

[0052] The optical unit 112 includes an interferometer 114, which receives the transmitted light Tx and provides it along the imaging device 102. For example, the interferometer 114 may couple the transmitted light into an optical fiber that extends along the length of the imaging device 102. The interferometer may also receive light (e.g., light received along the optical fiber) from the imaging device 102 and provide the received light to the detector 118. The received light may include a portion of the received light Rx that interacted with the tissue 107 and a local oscillator LO portion of the light reflected from the reference surface. The interferometer 114 may include a Faraday isolation device, such as a Faraday effect optical circulator, which may separate the optical paths of the returned received light Rx and local oscillator LO light from the transmitted light Tx. The separated Rx and LO light may then be directed to the detector 118. In some embodiments, optical unit 112 may include additional components (eg, lenses, filters, etc.), which may improve the performance of optical unit 112 and / or add additional functionality.

[0053] In some embodiments, system 100 may be a common-path OCT system, where the reference surface may be the end of an optical fiber within component 104, with Fresnel reflections causing a portion of the transmitted light Tx to reflect off the end of the fiber, while another portion of the transmitted light exits the fiber and interacts with optical component 104 (and thence with tissue 107). In other embodiments, system 100 may comprise a reference arm as a reference surface separate from the optical fiber within component 104.

[0054] The transmitted light Tx may interact with the tissue 107, and some of the light may be redirected (e.g., scattered, reflected, or a combination thereof) along the optical path, causing the redirected light to re-enter the catheter 102 and return to the optical unit 112 as received light Rx. The received light Rx may travel a longer distance than the LO light; therefore, differences in frequency, phase, and / or time may exist between the Rx light and the LO light. These differences may be used by the detector 118 (and / or the computing device 130) to determine the nature of the tissue 107. For example, the received light Rx and the local oscillator LO light may interfere with each other, generating an interference pattern in the detector 118. The interference pattern may be interpreted (e.g., by the computing device 130) to extract information about the difference between the distance traveled by the received light Rx compared to the distance traveled by the LO light. In the case of swept OCT, the difference can be encoded as a beat frequency heterodyned onto a carrier reference beam.

[0055] The detector 118 may convert light incident on the detector 118 (e.g., received light Rx and LO light) into an electrical signal. For example, the detector 118 may be an array detector (e.g., a CCD or CMOS) that provides a signal based on the amount and / or color of light incident on each pixel of the array.

[0056] The outer shaft 108 can be a long flexible tube configured to allow components such as guidewires, imaging components, drive shafts, sensor wires or fibers, imaging wires or fibers, cables, protective sheaths, parts therein, or combinations thereof to extend or pass through the imaging device lumen of the imaging device 102. The human interface device / position unit 120 may track and control both the outer shaft 108 and also the position of the inner member 105 relative to the outer shaft 108. For example, the position unit 120 may extend / retract the inner member 105 relative to the outer shaft 108 and / or rotate the inner member 105 relative to the outer shaft 108.

[0057] The human interface device / position unit 120 may include several electromechanical devices or sensors that convert the translational or angular / rotational motion of the imaging device 102, the inner member 105, or a combination thereof into digital signals or data. For example, the position unit 120 may include one or more linear encoders 122, rotary encoders 124, or a combination thereof. Human control and sensory feedback from the human interface device / position unit 120 may be used to enhance image visualization through the use and integration of neural networks to provide improved guidance to the physician during the procedure.

[0058] The one or more linear encoders 122 can be an optical linear encoder, a mechanical linear encoder, a magnetic linear encoder, an inductive linear encoder, a capacitive linear encoder, or a combination thereof. The linear encoder 122 can be an absolute encoder, an incremental encoder, or a combination thereof. The one or more linear encoders 122 can track or encode longitudinal / translational movement or displacement of the imaging device 102 and / or the inner member 105. For example, the one or more linear encoders 122 can track or encode longitudinal / translational movement or displacement of a proximal section of the inner member 105.

[0059] In these and other embodiments, the position unit 120 may also include one or more rotary encoders 124. The one or more rotary encoders 124 may be absolute rotary encoders, incremental rotary encoders, or a combination thereof. The one or more rotary encoders 124 may be optical rotary encoders, mechanical rotary encoders, magnetic rotary encoders, capacitive rotary encoders, or a combination thereof. The one or more rotary encoders 124 may track or encode the rotational or angular position of the imaging device 102 and / or inner member 105.

[0060] The position unit 120 may also include a motor and drive assembly 126. The motor and drive assembly 126 may be configured to translate the imaging device 102, the inner member 105, or a combination thereof longitudinally (e.g., distally, proximally, or a combination thereof). For example, the motor and drive assembly 126 may provide torque to or rotate a proximal section of the inner member 108, while the outer shaft 108 may remain fixed. This may rotate the optical component 106 to scan the transmitted light Tx around the distal tip 104. Rotation of the inner member 108 relative to the outer shaft 108 may also enable the tapered distal end of the optical component 106 to cut or otherwise “debulk” tissue to remove and / or cross an occlusion or partial occlusion, such as partial occlusion 109.

[0061] While the imaging device 102 is generally described in terms of imaging and interventions such as crossing, it should be understood that these operations may be only a portion of the functionality of the imaging device 102. For example, the inner member 105 and the outer shaft 108 may extend along one lumen of the imaging device 102, while other lumens are used for other tools or functions. For example, the imaging device 102 can also be used to deliver or otherwise introduce pharmaceutical compositions, including fluids, small molecules, and biologics, contrast agents, biomarkers, or combinations thereof, to the distal tip 104, to a target treatment site (e.g., a target vascular site within a patient's body) proximate the distal tip 104, or combinations thereof.

[0062] The control unit 110 may be coupled to the computing device 130. In some embodiments, the computing device 130 may be a separate component from the control unit 110. In some embodiments, the control unit 110 may be integrated with the computing device 130. In some embodiments, the control unit 110 may be configured as a handle or handheld unit. In other embodiments, the control unit 110 may be configured as a control box or tabletop unit. In some embodiments, the computing device 130 may be a desktop computer, a laptop computer, a tablet device, or a combination thereof. The computing device 130 may include a processor 132, such as a central processing unit (CPU), and memory 134. The processor 132 may have a 32-bit processor data bus or a 64-bit processor data bus. The processor 132 may be a dual-core, quad-core, or other multi-core processor. The processor 132 may operate at speeds of 3 GHz or greater. The memory 134 may include random access memory (RAM) and read-only memory (ROM). More specifically, the memory unit may comprise dynamic RAM (DRAM), static RAM (SRAM), synchronous DRAM (SDRAM), double data rate (DDR) SDRAM, double data rate 2 (DDR2) SDRAM, or a combination thereof. The optional GPU may comprise 8 GB or more of memory for implementing neural networks to analyze images in real time using machine or deep learning to improve their visualization and provide more visually intuitive images, for example, with warnings, notations, and augmented reality.

[0063] The computing device 130 can process and store images captured by the optical unit 112. The optical unit 112 and the computing device 130 can be combined with other devices to form part of an OCT imaging system. For example, the OCT imaging system can be a common-path OCT system, a time-domain OCT system, a spatial-frequency-domain OCT system, or a combination thereof. The computing device 130 can be coupled to the detector 118. The computing device 130 can receive signals, such as raw data, from the detector 118 and record sequences of raw data over time in memory 134. The processor 132 can perform one or more image processing steps and extract images from the raw data.

[0064] The processor 132 may cooperate with the control unit 110 to image the wall of the vessel within which the distal tip 104 is located. For example, the position unit 120 may rotate the inner member 105, which may in turn “scan” the optical unit's field of view around the vessel wall as the optical component 106 is rotated. The raw data generated by the detector 118 may be associated with a particular angular position of the inner member 105 relative to the outer shaft 108 (e.g., as reported by the rotational encoder 124). The processor 132 may use the angular information and the raw data to reconstruct an angular view of the vessel wall, which is greater than a single field of view of the detector 118. In some embodiments, the processor 132 may generate a 360-degree view of the vessel wall. Similarly, the processor 132 may also cooperate with the position unit 120 to construct an image extending along a longitudinal axis, which is greater than a single field of view, by moving the inner member 105 proximally / distally during imaging.

[0065] In some embodiments, the image generated by processor 132 may be displayed (e.g., displayed on a screen) by a user of system 100. In some embodiments, processor 132 may generate the display image at a rate (e.g., a video rate), which allows for "real-time" imaging of the vessel wall. In some embodiments, the use of a tapered distal tip may be based on the generated image.

[0066] The computing device 130 can also be configured to perform image registration on images captured by the optical unit 112. For example, image registration can involve using one or more transformation models to establish correspondence between features in a set of images and infer correspondence of additional features away from such features. Image registration can also be referred to as image matching. Image registration can also be performed to match or map images obtained from different imaging modalities (e.g., OCT with intravascular ultrasound (IVUS) or OCT with x-ray fluoroscopy).

[0067] 2 is a cross-sectional view of a distal end of an imaging device according to some embodiments of the present disclosure. Imaging device 200 may represent the distal end of an imaging device, which may be used as part of an imaging and intervention system, such as imaging and intervention system 100 of FIG.

[0068] The imaging device 200 includes an outer shaft 220 and an inner element 210. The inner element 210 may rotate relative to the outer shaft 220 and may be used for both imaging and intervention. The inner element 210 includes an optical element 202, which includes a tapered distal end 204 and a reflective surface 206. The reflective surface 206 may be configured to redirect light between one or more optical fibers 212 of the inner element 210 and an imaging target (e.g., a field of view). As shown in the example of FIG. 2, the reflective surface 206 redirects light received from the optical fiber 212 (e.g., transmitted light Tx in FIG. 1 ) into an imaging beam 208, which extends outward from the periphery of the imaging device 200. The reflective surface 206 may also redirect received light (e.g., Rx in FIG. 1 ) back into the optical fiber 212. The tapered distal end 204 may include one or more tissue contacting surfaces (here, conical tissue contacting surfaces), which may extend a distance "d" from the front surface of the outer shaft 220.

[0069] The outer shaft 220 may be the outer body of the imaging device 200. The outer shaft 220 may have an outer diameter of about 0.020 inches (0.508 mm) or less. In another embodiment, the outer shaft 220 may have an outer diameter of about 0.045 inches (1.143 mm) or less. The outer shaft 220 may be approximately the size of a guidewire. The outer shaft 220 may be fixed relative to the inner element 210 (e.g., to a control or optical unit). Thus, the outer shaft 220 may be a torque shaft, which may remain fixed while the inner element 210 rotates within the outer shaft 220.

[0070] The outer shaft 220 may have a body 222 and a cap 224. The cap 224 may be located at the distal end of the outer shaft 220. The cap 224 may allow light to pass from outside the outer shaft 220 into the lumen of the outer shaft 220 (e.g., it may allow light to pass from outside the outer shaft 220 into the inner element 210). In some embodiments, the cap 224 may be a separate component attached to the end of the body 222. In some embodiments, the cap 224 may be integral with the body 222, and the cap 224 may point to the distal end of the body 222. The body 222 may be formed from a coil or modified hypotube. Both the body 222 and the cap 224 may be generally tubular members, with the lumen of the inner element 210 disposed therein. The body 222 and the cap 224 may have similar outer diameters and thicknesses in some embodiments. In some embodiments, the body 222 and the cap 224 may have different outer diameters and / or thicknesses from one another.

[0071] In some embodiments, the cap 224 may be an optically transparent material. For example, the cap 224 may be made of a different material than the body 222 of the outer shaft 220. In some embodiments, the cap 224 may include a window, such as a window that is laser cut through the material of the cap 224. In some embodiments, the laser cut window may include a cover that is made of an optically transparent material. In some embodiments, the window may be uncoated. In some embodiments, the body 222 of the outer shaft 220 may be made of an optically transparent material and a separate cap 224 may be unnecessary.

[0072] In some embodiments, cap 224 may include a positive stop 226, which limits movement of inner member 210 relative to outer body 220. Positive stop 226 may limit longitudinal movement of inner member 210 relative to outer body 220 (e.g., movement along the longitudinal axis of imaging device 200). For example, the inner diameter of cap 224 at positive stop 226 may be less than the outer diameter of inner member 210. In some embodiments, positive stop 226 may be a tapered section of cap 224 and / or a step on the inner wall of cap 224.

[0073] The inner member 210 may be a generally cylindrical member that is disposed within the lumen of the outer shaft 222. The inner member 210 may have an outer diameter of about 0.010 inches (0.254 mm) or less. In another embodiment, the outer shaft 210 may have an outer diameter of about 0.018 inches (0.457 mm) or less. The inner member 210 may be movable relative to the fixed outer shaft 220. The inner member 210 may be extendable / retractable relative to the outer shaft 220 along the longitudinal axis of the imaging device 200 and may be rotatable relative to the outer shaft 220. For example, a motor / drive assembly (e.g., 126 in FIG. 1 ) may move the inner member 210 relative to the outer shaft 220.

[0074] The inner member 210 includes an optical fiber 212. The optical fiber 212 may transmit light between an optical unit (e.g., 112 in FIG. 1 ) coupled to the proximal end of the imaging device 200 and the distal end of the imaging device 200. The optical fiber 212 may be a single fiber or a multi-core fiber. The optical fiber 212 may be surrounded by a cladding material 211, which may support the optical fiber 212 and provide optical conditions (e.g., refractive index mismatch) that enable the transmission of light along the optical fiber 212. The cladding material 211 may in turn be surrounded by a fiber stiffener 216. The fiber stiffener 216 may support the optical fiber 212 and the cladding material 211. In some embodiments, the fiber stiffener 216 may be a coil or a modified hypotube. A portion of the optical component 202 may extend beyond the distal end of the fiber stiffener.

[0075] The optical fiber 212 (and cladding material 211) may terminate at a reference surface 214. The reference surface 214 may be at a distal end of the optical fiber. In some embodiments, the reference surface 214 may be a generally flat surface (e.g., cut into the fiber) that is perpendicular to the long axis of the imaging device 200. The reference surface 214 may reflect a portion of the transmitted light along the optical fiber 212. The light reflected from the reference surface 214 may be a local oscillator (LO) portion of the light, which may be coherently combined with light received in an optical unit (e.g., optical unit 112 of FIG. 1 ).

[0076] Inner member 210 includes optical component 202. Optical component 202 may be a single element, which includes reflective surface 206 and tapered distal end 204. Optical component 202 may be a single piece of material, which has one or more surfaces shaped to form reflective surface 206 and one or more surfaces shaped to form tapered distal end 204. In an exemplary embodiment of optical component 202, reflective surface 206 and tapered distal end 204 may be separate surfaces of optical component 202.

[0077] The optical component 202 may be a generally cylindrical element, a portion of which may be disposed within the fiber reinforcement 216. The optical component 202 may be formed from a single material. For example, the optical component 202 may be formed from aluminum oxide, zirconium oxide, silicon carbide, diamond, or a combination thereof. In some embodiments, the optical component 202 may be a metal, such as SS304.

[0078] The tapered distal end 204 may be a tool for coronary intervention, such as a crossing tool. The tapered distal end 204 may be a tissue-contacting surface that extends a distance d from the distal tip of the outer shaft 220 when the inner member 210 is extended to the positive stop 226. In some embodiments, the distance d may be approximately 1 mm or less. The tapered distal end 204 may be formed along the distal end of the optical component 202. For example, the tapered distal end 204 may be a conical surface that extends to a point. In some embodiments, the point of the tissue-contacting surface may be along the long axis of the imaging device 200. In some embodiments, the point of the conical surface may be offset from the long axis of the imaging device 200.

[0079] The reflective surface 206 of the optical component 202 may be a reflective surface that redirects light from an optical axis that is approximately aligned with the long axis of the fiber and an optical axis that is directed toward one side of the imaging device 200. For example, the reflective surface 206 may redirect light at approximately a right angle. The reflective surface 206 may be a beveled surface at the proximal end of the optical component 202. The angle of the optic 206 relative to the long axis of the imaging device 200 may be selected based on the desired deflection of light reflecting from the reflective surface 206. For example, in some embodiments, the reflective surface 206 may have an angle of approximately 45 degrees. In some embodiments, the reflective surface 206 may be coated with a reflective material. For example, the reflective surface of the reflective surface 206 (e.g., the proximal surface of the optical component 202) may be gold coated.

[0080] As shown by the exemplary rays of the imaging beam 208, light transmitted through the optical fiber 212 may diverge as it exits the optical fiber 212 at the reference surface 214. The diverging rays of the imaging beam 208 may then be redirected by the reflective surface 206 such that the imaging beam 208 forms a diverging cone of transmitted light extending out one side of the imaging device 200. The fiber stiffener 216 may include a window (and / or be made from a transparent material) to allow the imaging beam 208 to pass out of the inner member 210 (and from there out of the imaging device 200).

[0081] Thus, as the inner member 210 rotates relative to the outer shaft 220, the imaging beam 208 may be swept around the circumference of the imaging device 200. The inner member 210 may also be movable relative to the outer shaft 220 along the longitudinal axis of the imaging device 200. The field of view represented by the imaging beam 208 may be swept around the imaging device 200 in a 360-degree arc and moved along an imaging range L longitudinally relative to the position of the imaging device. The imaging range may be defined by the farthest extension of the inner member 210 within the outer shaft 220 (e.g., when the inner member 210 abuts the positive stop 226) and by the length of the transparent portion of the outer shaft 220 (e.g., the transparent portion of the cap 224). In some embodiments, the imaging range L may be approximately 5-25 mm.

[0082] The imaging beam 208 may interact with the environment surrounding the imaging device 200. For example, when the imaging device 200 is within a blood vessel, the imaging beam may illuminate a portion of the blood vessel wall around the imaging device 200. As the inner member 210 rotates, the imaging beam 208 may sweep around it, illuminating a strip of the vessel wall. Light may be returned from the illuminated tissue to the imaging device 200. For example, some of the illumination light may be scattered and / or reflected by one or more components and structures of the tissue. Some of the illumination light may penetrate into the tissue for a distance before being returned to the imaging device 200. Some of the returned light may follow an optical path that reflects off the imaging tool 206 and is coupled into the optical fiber 212. The returned light coupled into the fiber may form the received light (e.g., the received light Rx of FIG. 1 ).

[0083] The inner member 210 may include a filler material 218 between the distal end of the optical fiber 212 (e.g., the reference surface 214) and the proximal surface of the optical component 202 (e.g., the reflective surface 206). Because the reference surface 214 and the reflective surface 206 may be at different angles relative to the longitudinal axis of the imaging device 200, a gap may exist between the reference surface 214 and the optical component 202. The filler material 218 may be an optically transparent material that allows the imaging beam 208 (and the received light) to pass through the filler material 218. In some embodiments, the filler material 218 may have a refractive index that matches the refractive index of the optical fiber 212 and is selected to prevent refraction of light at the optical fiber / filler interface. For example, the filler material may have a refractive index of approximately 1.55. In other examples, the filler material may have a refractive index within a range of 1.40 to 1.80, 1.50 to 1.60, or 1.55 to 1.65. In some embodiments, the filler material 218 may be an adhesive and may help bond the optical component 202 to the optical fiber 212 and the cladding 211. In some embodiments, the filler material 218 may also fill windows in the fiber stiffener 216.

[0084] 3 is a cross-sectional view of a distal end of an imaging device according to some embodiments of the present disclosure. Imaging device 300 may represent the distal end of an imaging device, which may be used as part of an imaging and intervention system, such as imaging and intervention system 100 of FIG. 1. Imaging device 300 may include many features similar to imaging device 200 of FIG. 2. For brevity, the features and operations described above with respect to imaging device 200 will not be repeated with respect to imaging device 300 of FIG. 3.

[0085] The imaging device 300 includes an optical component 302, which includes a single distal surface 304 that acts as both a reflective surface and a tapered distal end. The optical component 302 may be generally cylindrical with a generally trapezoidal longitudinal cross-section. The optical component 302 may be formed from an optically transparent material (e.g., sapphire), and light may pass into the material of the optical component 302 through a proximal surface 307 of the optical component 302. The proximal surface 307 is angled (with respect to the long axis of the imaging device 300) to minimize reflection of light as it passes from the filler material 318 into the material of the optical component 302.

[0086] The distal surface 304 of the optical component 302 may extend a distance d from the distal tip of the outer shaft 320. The distal surface 304 may be a generally flat surface at an angle to the long axis of the imaging device 300. The distal surface 304 may be a point at a distance d beyond the outer shaft 320, which may act as a cross tool. Light from the optical fiber 312 may reflect from the distal surface 304 within the optical component 302. In some embodiments, the distal surface 304 may be angled to set a total internal reflection (TIR) ​​condition at the distal surface 304. In some embodiments, the distal surface 304 may be coated with a reflective material (e.g., gold). Thus, the optical component 302 has a single surface (e.g., the distal surface 304) that acts as both a tapered distal end and a reflective surface.

[0087] 4 is a cross-sectional view of a distal end of an imaging device according to some embodiments of the present disclosure. Imaging device 400 may represent the distal end of an imaging device, which may be used as part of an imaging and intervention system, such as imaging and intervention system 100 of FIG. 1. Imaging device 400 may include many features similar to imaging device 200 of FIG. 2 and imaging device 300 of FIG. 3. For brevity, the features and operations described above with respect to imaging device 200 and / or imaging device 300 of FIG. 3 will not be repeated with respect to imaging device 400 of FIG. 4.

[0088] Similar to optical component 302 of FIG. 3 , optical component 402 includes a distal surface 404, which is both a tapered distal end and a reflective surface. Imaging device 400 also includes a lens 409 disposed between a reference surface 414 of optical fiber 412 and a proximal surface 407 of optical component 402. Lens 409 may shape imaging beam 408. For example, lens 409 may focus imaging beam 408 to focus imaging beam 408 to a focal point. The focal length of lens 409 may be selected (e.g., based on the expected distance from imaging device 400 to the vessel wall) to focus imaging beam 408 on the vessel wall or a focal region therein. In some embodiments, lens 409 may be a gradient index (GRIN) lens. In imaging device 400, reference surface 414 may be at the distal end of lens 409.

[0089] In this and other variations of the exemplary embodiments described herein, lens 409 may be, but is not limited to, a Fresnel lens, a spherical lens, an aspherical lens, or an anamorphic lens. The lens may also be selected to either focus light at a selected distance from the external exit surface of the imaging beam, as depicted in FIGS. 22E and 22F, or to provide a collimated beam profile, as depicted in FIGS. 22C and 22D, or to produce variable degrees of focusing power, including collimation, at different angular orientations across the beam. Lens 409 may also comprise a lens assembly with two or more lenses. Additional features related to lenses in OCT imaging systems are provided later below.

[0090] 5A and 5B are schematic diagrams of exemplary imaging devices with bent or angled regions according to some embodiments of the present disclosure. Figures 5A and 5B depict imaging devices 502 and 504, respectively, including pre-shaped bends that can aid in directional crossing with a tapered distal end. Imaging device 502 may be an imaging device such as imaging device 300 of FIG. 3 and imaging device 400 of FIG. 4, in which the optical component has a single surface that acts as both the tapered distal end and the reflective surface. Imaging device 504 may be an imaging device such as imaging device 200 of FIG. 2, in which the optical component has a first surface that acts as the reflective surface and a second surface that acts as the tapered distal end.

[0091] 6A and 6B are schematic diagrams of another embodiment of an imaging cross device 600, comprising a molded or shaped optical element 602. The molded optical element 602 may comprise one or more structures 604 and 606 configured to facilitate handling, manipulation, and / or alignment of the optical element 602 during manufacturing and / or use. The device 600 may further comprise an optical fiber 608 to transmit light between a proximal light source or light receiver and the optical element 602. The optical fiber 608 may be a single-mode fiber or a multimode fiber. A lens 610 may be provided to optically couple the fiber 608 and the optical element 602. The lens 610 may be, for example, a gradient index lens fused at its proximal end 612 to the distal end of the fiber 608 and configured to collimate or focus light from the light source and fiber 608 onto a reflective surface 614 of the optical element 602. The fiber 608, lens 610, and optical element 602 may be housed within a hypotube 616 of the device 600. The device 600 may be used within a catheter 618. In the particular embodiment depicted in FIGS. 6A and 6B, the hypotube 616 has an outer diameter of 0.010 inches, or 0.017 inches, or 0.022 inches, although in other embodiments, the hypotube has an outer diameter in the range of 0.009 inches to 0.022 inches, or 0.012 inches to 0.020 inches. The catheter 618 may have an inner diameter in the range of 0.010 inches to 0.013 inches, or 0.018 inches to 0.02 inches, or 0.020 inches to 0.024 inches, or may otherwise be configured with a diameter to receive the hypotube 616 of the device 600. The outer diameter of the catheter 618 may be in the range of 0.016 inches to 0.020 inches, or 0.016 inches to 0.017 inches, or 0.018 inches to 0.045 inches. The inner and / or outer surfaces of the hypotube 616 and catheter 618 may comprise a lubricious coating to facilitate rotational or longitudinal movement of the device 600 or catheter 618.

[0092] 6A and 6B , optical element 602 comprises first and second protruding flanges or structures 604 and 606. Protruding structures 604 and 606 may be used to grip and manipulate optical element 602 and / or to facilitate alignment while reducing the risk of damage to the optical properties of optical element 602. In this particular embodiment, structure 604 comprises a smaller cross-sectional shape than structure 606, with a lateral width and / or longitudinal length that is smaller than the lateral width or dimensions of the other structures 606. However, in some embodiments, structures 604 and 606 may be located at, proximally aligned with, and contiguous with proximal end 620 of optical element 602. These structures 604 and 606 may be sized and shaped to facilitate insertion of optical element 602 and / or alignment with hypotube 616. 8A-8D , hypotube 616 comprises an inner lumen 622 for receiving fiber 608 and optical element 602, a proximal opening (not shown), and a distal opening 623 through which optical element 602 may partially protrude. Hypotube 616 further comprises an insertion opening 626 through which optical element 602 may be inserted into inner lumen 622. Insertion opening 626 may be configured with a length sufficient to receive optical element 602 and have structure 604 to be seated in a matching recessed opening 628 opposite insertion opening 626 such that a distal end of optical element 602 may protrude from distal opening 624 of hypotube 616. Matching opening 628 and protruding structure 604 may be configured to receive protruding structure 604 or form a complementary interfit between opening 628 and structure 604. When the optical element 602 is fully seated within the hypotube 616, the distal surface 630 of the protruding structure 606 may abut the distal surface 632 of the insertion opening 626. The protruding structures 604 and 606 may further include cylindrically rounded side surfaces 634 and 636, which may align with the outer diameter of the hypotube 616 when the optical element 602 is fully seated. As depicted in FIG. 6A , the lens 610 may be pushed distally to abut and bond against the proximal surface of the optical element 602.

[0093] 7A-7E, the optical element 602 may include an inner core 700 and an outer molded shell 702. The material for the inner core 700 may be a high refractive index polymer, such as, but not limited to, polyurethane, polyvinylpyrrolidone, polystyrene, polycarbonate, ZEONEX, or NAS-21, and the material for the outer molded shell 702 may be the same as that of the inner core 700 or an optical polymer, such as, but not limited to, polymethylmethacrylate (PMMA), OPTOREZ, or cellulose. The inner core 700 may have a refractive index of approximately 1.55, but in other embodiments, may have a refractive index in the range of 1.40 to 1.80, or 1.50 to 1.60, or 1.55 to 1.65. The length of the optical element may be approximately 500 microns, but in other embodiments, may be in the range of, for example, 400 microns to 800 microns, or 500 microns to 600 microns, or 450 microns to 550 microns. The optical element 602 comprises a cylindrical body 706 having a diameter of approximately 150 microns, but in other embodiments, may be in the range of 140 microns to 200 microns or 140 microns to 160 microns. The distal end of the cylindrical body 706 may comprise a reflective surface 708 oriented at 45 degrees relative to a longitudinal optical axis 710 of the optical element 602. The cylindrical body 706 may further comprise a side interface surface 712 from which light reflected from the reflective surface 708 exits the optical element 602 and from which light reflected back from surrounding tissue structures is received. The side interface surface 712 may be formed or oriented at an angle of 5 degrees to 8 degrees inward from the outer diameter of the cylindrical body 706 and may have a maximum width of approximately 60 microns and a length of 135 microns. In other examples, the width may be in the range of 40 microns to 80 microns and the length may be in the range of 100 microns to 180 microns. 7E, the side interface surface 712 has a planar configuration with a parabolic shape with an apex 714 proximal to a distal edge 716 located at the proximal end of the optical element 602. The side interface surface 712 and the reflective surface 708 may share a common edge 720, as shown in FIG.

[0094] The inner core 702 may have a generally cylindrical shape with an orthogonal proximal surface 722 and an angled distal surface 724 aligned with the reflective surface 708. However, in other embodiments, the core may have a flattened surface distally. The inner core 702 may have a diameter within a range of 100 to 150 microns or 110 to 130 microns. In some variations, the inner core 702 may have a variable diameter or lateral shape. In Figures 7C and 7D, for example, the inner core 702 may have a diameter of approximately 110 microns at its proximal end and a diameter of approximately 125 microns at its distal end.

[0095] Protruding structures 604 and 606 are located on opposite sides of cylindrical body 706. Structures 604 and 606 may protrude the same or different distances from the surface of cylindrical body 706. In some variations, the total protruding distance may be approximately 100 microns or in the range of 90 microns to 120 microns. Individually, each structure 604 and 606 may have a protruding distance of 40 to 60 microns or in the range of approximately 50 to 55 microns.

[0096] 6A, light traveling through fiber 608 is collimated or focused by lens 610 on a reflective surface 708 of optical element 602. Reflective surface 708 is an interior surface of the optical element that faces or is complementary to an exterior surface 726 of a tapered or angled distal end 728. In some variations, exterior surface 726 may further comprise a reflective material, such as a gold or other metallic coating, to promote reflection. To promote bonding of the coating, the surface may be mechanically or chemically treated to roughen the surface and improve bonding.

[0097] However, in other embodiments, the reflective surface of the optical element may comprise an outer reflective surface. FIG. 9 depicts another embodiment of an imaging crossing device 900, comprising an optical element 902 with a cylindrical body 904 having a length in the range of 500 microns to 1,000 microns, and a reflective surface 906 located at the proximal end of the optical element 902 and spaced from a tapered or angled penetrating distal end 908 of the optical element 900. In this embodiment, the device 900 also comprises a hypotube 908, a fiber 910, and a lens 912, where the hypotube 908 comprises an imaging cavity 914 filled with an optically transparent polymer or adhesive 916. The lens 912 is closer to the reflective surface 906 in the device 900 compared to the more distal reflective surface in the device 600 of FIGS. 6A and 6B and is therefore configured to collimate or focus light from the fiber 910 onto the surrounding tissue at a different focal length. Reflective surface 906 may also be treated and / or coated with a reflective material, as described for reflective surface 708 of device 600. In embodiments comprising an outer reflective surface, the material of the optical element need not be optically transparent and may comprise a metal such as steel, a polished reflective surface, or a material such as ceramic or glass, including sapphire or sapphire fiber.

[0098] Many optical adhesives or curable materials that can be used as optically transparent polymers, adhesives, or filler materials have refractive indices greater than 1.5, which results in a significant refractive index mismatch with saline, blood, and / or plasma, which may have refractive indices in the range of 1.33 to 1.38. This results in visible artifacts, including residual images, streaks, and / or rings. Figure 18A, for example, depicts an OCT image with a ring artifact 1802 from an interface mismatch and a streaking artifact 1804 resulting from a strong refractive index mismatch that saturates the detector. Figure 18B is another example OCT image with a ring artifact 1812 and streaks 1814. Figure 18C is yet another example OCT image with a ring artifact 1816 and residual image 1818. Potentially, to ameliorate these artifacts, the contour of the filler material may be modified during manufacturing from a cylindrical shape to a concave or convex shape along the length of the filler material to dereflect the refractive index mismatch signal from the detector. Figure 19A depicts back reflection 1902 from a mismatched filler / fluid interface 1904 between the optical filler 1806 and the surrounding fluid / tissue 1906, while Figures 19B and 19C depict concave and convex interfaces 1914, 1924, respectively, centered about the lateral optical axis. Figures 19D and 19E depict concave and convex interfaces 1934, 1944 that are proximal to or offset from the lateral optical axis, reducing back reflections 1932, 1942.

[0099] In some variations, an optically transparent polymer, adhesive, or filler material may be selected with a refractive index less than or equal to 1.5. For example, an aliphatic urethane acrylate with an acrylic monomer may be used, with a refractive index in the range of 1.30 to 1.40. Such materials may improve manufacturing tolerances, repeatability of the manufacturing process, and manufacturability because they are less sensitive to reflection variations caused by highly refractive index-mismatched meniscus concave / convex shapes and interfaces, thereby minimizing or eliminating undesirable detector saturation and image lag.

[0100] In some variations, the filler material may be a UV-curable optical adhesive comprising a mixture of aliphatic urethane acrylate and acrylic monomers. Examples include Norland Optical Adhesives 133 and 13775 (Norland Products, Inc., Cranbury, NJ). NOA133 has a refractive index of 1.33 and a viscosity before curing of 15 cps, and comprises a mixture of 1-15% aliphatic urethane acrylate and 85-99% acrylic monomers, while NOA13775 has a refractive index of 1.3775 and a viscosity before curing of 4,000 cps, and is a mixture of 80-99% aliphatic urethane acrylate and 1-20% acrylic monomers. In some variations, the choice of filler material used may be selected based on manufacturing characteristics such as the desired refractive index and viscosity. A viscosity of 15 cps is too thin to be easily manufactured, while a viscosity of 4,000 cps is too thick, i.e., viscous, to be easily manufactured. For example, smaller volumes may be difficult to handle. In some variations, the viscosity of the filler material may be within the range of, for example, 1,000 to 3,000 cps, 1,500 to 3,000 cps, or 2,000 to 2,500 cps. Other polymeric materials, including aliphatic urethane acrylates and acrylic monomers, with refractive indices of 1.30 to 1.40, pre-cure viscosities of 1,000 to 3,000 cps, and post-cure Shore D hardnesses greater than 30 may also be applicable. Another example of a low refractive index polymeric material or filler is a combination of hexafluoroacetone and 3-aminopropyltriethoxysilane.

[0101] The viscosity of the filler material can be further selected or modified, for example, by selecting materials with different relative amounts of aliphatic urethane acrylate and acrylic monomer, but the optical properties may or may not exhibit a linear relationship based on the relative percentages or ratios of the components. For example, a mixture of 50% NOA133 and 50% NOA13775 by volume (40%-57% aliphatic urethane acrylate and 43%-60% acrylic monomer) had a refractive index of 1.274 at 1,310 nm, while a mixture of 40% NOA133 and 60% NOA13775 by volume (48%-65% aliphatic urethane acrylate and 35%-52% acrylic monomer) had a refractive index of 1.345 at 1,310 nm. In other variations, the percentage of aliphatic urethane acrylate is in the range of 30% to 70% and the percentage of acrylic monomer is in the range of 70% to 30%, while in yet other variations, the percentage of aliphatic urethane acrylate is in the range of 40% to 50% and the percentage of acrylic monomer is in the range of 60% to 50%.

[0102] Two or more mixtures of optical adhesives with different refractive indices may be combined before curing to achieve a desired or optimal refractive index. For example, a mixture of 50% NOA133 and 50% NOA13775 (40%-57% aliphatic urethane acrylate and 43%-60% acrylic monomer) by volume had a refractive index of 1.274 at 1,310 nm, while a mixture of 40% NOA133 and 60% NOA13775 (48%-65% aliphatic urethane acrylate and 35%-52% acrylic monomer) by volume had a refractive index of 1.345 at 1,310 nm. The mixing ratio to achieve the desired refractive index may or may not be linear or proportional. The refractive indices before and after curing may or may not be different. A post-curing refractive index of 1.33 to 1.35 can be index-matched to water, saline, and fluids, while a post-curing refractive index of 1.37 to 1.40 can be index-matched to soft tissue.

[0103] 20A-20C depict various OCT images from an imaging system using a UV-cured filler material comprising a 40 / 60 mixture of NOA133 and 13775. As depicted, the signal intensity from ring artifacts 2002, 2006, 2010, 2012 arising from the filler / fluid interface is substantially reduced compared to that in FIGS. 18A-18C. This, in turn, reduces the incidence of residual images as well as the detector saturation and corresponding light fringes seen in FIGS. 18A and 18B.

[0104] The low refractive index filler materials described herein may be used with any of a variety of OCT imaging devices and systems, whether used in an aqueous or biological environment, and are not limited to the various exemplary OCT imaging embodiments described herein. For example, the low refractive index filler materials described herein may be used with OCT imaging probes that may or may not include a cutting tip or distal tapered end or edge 204, 304, 404, 716, or 1004 described herein.

[0105] 21A is a cross-sectional view of an exemplary distal end of an OCT imaging device 2100 with a low-index filler material 2118 positioned between the distal end of an optical fiber 2114 and the reflective surface 2106 of the tip structure 2102. The imaging device 2100 may include an inner core 2110 positioned within a lumen 2115 of an outer tubular shaft 2120. The inner element 2110 may include an optical fiber 2112 configured to rotate relative to the outer shaft 2120 and transmitting light from a light source and receiving a returning light signal from the target structure. Light from the light source travels distally through the optical fiber 2112, exits the end 2114 of the optical fiber 2112, and passes through the optical filler material 2118 before reflecting off the reflective surface 2106 of the tip structure 2102 and redirecting the imaging beam 2108 toward the target structure.

[0106] The outer shaft 2120 may have an outer diameter of about 0.020 inches or less, 0.045 inches or less, or may comprise a diameter sized according to common guidewire sizes, including 0.014 inches, 0.018 inches, and 0.35 inches. The outer shaft 2120 may comprise a one-piece design or may comprise a body 2122 and a cap 2124 that are joined during the manufacturing process. The body 2122 may be formed from a coil or hypotube. The body 2122 and cap 2124 may have similar or different outer diameters and wall thicknesses. As with other variations described herein, the cap 2124 may comprise a different material, e.g., an optically transmissive material, to facilitate light transmission through the cap 2124. In some embodiments, the cap 2124 may include a window, such as, for example, a window laser cut through the material of the cap 2124. In some embodiments, the laser cut window may include a cover made from an optically clear material. In some embodiments, the window may be uncoated. In some embodiments, the body 2122 of the outer shaft 2120 may be made from an optically clear material, and a separate cap 2124 may not be necessary.

[0107] The inner core 2110 may be a generally cylindrical member that is disposed within the lumen 2115 of the outer shaft 2120. The inner core 2110 may have an outer diameter of about 0.010 inches (0.254 mm) or less. The inner core 2110 may be extendable / retractable along the longitudinal axis of the imaging device 2100 relative to the outer shaft 2120 and may be rotatable relative to the outer shaft 2120. For example, a motor / drive assembly (e.g., 126 in FIG. 1 ) may move the inner core 2110 relative to the outer shaft 2120. This may facilitate movement of the imaging area without requiring movement of the outer shaft 2120.

[0108] The optical fiber 2112 is configured to transmit light between an optical unit (e.g., 112 in FIG. 1 ) coupled to the proximal end of the imaging device 2100 and the distal end of the imaging device 2100. The optical fiber 2112 may be a single fiber or a multi-core fiber. The optical fiber 2112 may be surrounded by a cladding material 2111, which may support the optical fiber 2112 and provide optical conditions (e.g., refractive index mismatch) that facilitate light transmission along the optical fiber 2112. The cladding material 2111 may in turn be surrounded by a fiber stiffener 2116. The fiber stiffener 2116 may support the optical fiber 2112 and the cladding material 2111. In some embodiments, the fiber stiffener 2116 may be a coil or a modified hypotube.

[0109] The end 2114 of the optical fiber 2112 (and cladding material 2111) may be a flat surface (e.g., cleaved into the fiber) that is perpendicular to the longitudinal axis of the imaging device 2100, although in other variations it may comprise a surface that is non-orthogonally oriented. Some light traveling distally through the fiber 2112 may be reflected back at the end 2114 of the fiber 2112 and serve as a local oscillator (LO) portion of light that is coherently combined with light received within the optical unit (e.g., optical unit 112 of FIG. 1).

[0110] The reflective surface 2106 of the tip structure 2102 is configured to redirect light from an optical axis that is approximately aligned with the longitudinal axis of the fiber 2112 and directed toward one side of the imaging device 2100. For example, the reflective surface 2106 may redirect light at approximately a right angle. The reflective surface 2106 may be a beveled surface at the proximal end of the tip structure 2102. The angle of the reflective surface 2106 relative to the longitudinal axis of the imaging device 2100 may be selected based on the desired deflection of light reflecting from the reflective surface 2106 that may be configured. For example, in some embodiments, the reflective surface 2106 may have an angle of approximately 45 degrees. In some embodiments, the reflective surface 2106 may be coated with a reflective material such as gold. 21A , a low refractive index filler material 2118 described herein is located between the end 2114 of the optical fiber 2112 (or a lens located at the end 2114 of the optical fiber 2112) and the reflective surface 2106 of the tip structure 2102. The refractive index mismatch between the outer surface 2130 of the filler material 2118 and the surrounding fluid or tissue is reduced as well as image artifacts as a result of the low refractive index material used.

[0111] In other variations, as depicted in FIG. 21B, an outer tubular shaft is not provided or required as the imaging device 2150 is configured for insertion and use inside the lumen of a catheter or other tool to provide OCT imaging, but may otherwise resemble the inner core structure 2110 of the imaging device 2100 in FIG. 21A.

[0112] Referring to FIG. 22A , in other variations, an OCT imaging system 2200 may include an optical fiber 2202, a lens 2204, a mirror or reflector 2206, and a low-index filler material 2208 between the lens 2204 and the reflector 2206. As described elsewhere, the optical fiber 2202 may be a single-mode fiber, but in other variations, it may be a multimode fiber. The distal surface 2210 of the fiber 2202 and the proximal surface 2212 of the lens 2204 may be mechanically spliced ​​or fusion spliced. The surfaces 2210 and 2212 may be cut or cleaved with complementary geometries and then mechanically aligned. This may be a planar surface, each perpendicular to the axis of the fiber 2202, but in other variations, may include a non-planar surface or a non-perpendicular orientation of the surfaces. FIG. 29A depicts an example of an OCT imaging system 2900 mechanically spliced ​​with an optical fiber 2902, with a distal surface 2904 that is flat and oriented 90 degrees relative to the longitudinal axis of the fiber 2902. This surface 2904 is oriented 90 degrees relative to a corresponding proximal surface 2906 of a lens 2908, which is also flat. As further depicted in FIG. 29A, a distal region 2910 of the optical fiber 2902 may have its jacket 2912 removed. In some further variations, as depicted in FIG. 29B, after splicing, the fiber 2902 and lens 2204 may be recoated, partially or completely re-jacketed, which may improve streaks, rings, image lag, and other image artifacts. In a further variation, an optical adhesive with a refractive index similar to that of the fiber 2902 and / or lens 2904 may be used, or the fiber 2202 and lens 2204 may be fused or welded together. This fusion may result in loss of single-mode coupling and may create an intermediate zone 2914 of optical functionality between the optical fiber 2902 and the lens 2904.

[0113] Referring back to FIG. 22A , lens 2204 may be a GRIN lens. In this particular embodiment, the length of the GRIN lens corresponds to one-quarter of the full sinusoidal path, or pitch, of lens 2204, although in other variations it may comprise a length equal to or corresponding to any odd multiple of a quarter pitch, e.g., ¾ pitch length, 1 1 / 4 pitch length 2300 ( FIG. 23A ), 1 ¾ pitch length 2302 ( FIG. 23B ), or greater. One potential benefit of the increased length is that ring-like artifacts (e.g., artifacts 2004, 2008, 2012 in FIGS. 20A, 20B, and 20C ) resulting from reflective interfaces between optical fibers 2304, 2306 and GRIN lenses 2308, 2310, respectively, will exhibit an increased diameter in the image, such that the ring-like artifact may expand to a size that is outside the effective field of view. This reflection artifact is typically stronger or greater than -40 dB.

[0114] As depicted in FIG. 22A , the GRIN lens 2204 may output a collimated beam 2220 that passes through a low-index material 2208 and is reflected by a mirror or reflector 2206. The beam diameter may be configured to be nominally in the range of 20 μm to 200 μm. The distal surface 2214 of the GRIN lens 2204 and the polymer material 2208 may also be at a 90-degree surface angle with respect to the axis of the optical fiber 2202. This may ensure that any light rays reflecting at the lens / polymer interface will have the same reflection path of partial reflection, which may provide improved consistency / reproducibility during manufacturing and provide a stable and optimal return loss (RL) or reference signal. In some variations, the RL at the lens / polymer interface may be in the range of, for example, −14 dB to −28 dB, or −15 dB to −35 dB, or −20 dB to −40 dB.

[0115] 22C and 22D depict a generalized, enlarged schematic diagram of one embodiment of an OCT imaging assembly 2260 configured with a collimated beam 2270, comprising a single-mode optical fiber 2262, a GRIN lens 2264, a low-index polymer material 2266, and a mirror 2268. The light beam 2270 will exit the single-mode optical fiber 2262 and be collimated by the GRIN lens 2262; however, at the interface between the GRIN lens 2262 and the low-index polymer 2266, partial reflection of the collimated beam 2270 occurs, typically with an RL in the range of −14 dB to −35 dB. Depending on the specific design, an RL range of −14 dB to −40 dB, or −15 dB to −35 dB, or −20 dB to 35 dB, or −25 dB to −35 dB may be achieved. As this reflected beam 2272 travels back toward the optical fiber 2262, the GRIN lens 2264 focuses the reflected beam back into the single-mode fiber core 2274, which may have a size of, for example, 10 μm or less, 9 μm or less, or 8 μm or less. This may result in a high effective RL of the reference signal. This high RL is achieved at a local maximum of the optimal GR length for beam collimation, which may be found at or around 0.5 pitch units, 0.75 pitch units, 1.25 pitch units, 1.75 pitch units, etc., which may be beneficial for improving manufacturability and repeatability and allowing for a + / −10% tolerance around the optimal GRIN unit length.

[0116] In comparison, OCT imaging assembly 2280, illustrated in FIGS. 22E and 22F, is configured with a focused light beam 2290 and includes a single-mode optical fiber 2282, a GRIN lens 2284, a low-index polymer material 2286, and a mirror 2288. As light beam 2290 exits single-mode optical fiber 2282, it is partially focused by GRIN lens 2284 and then partially reflected at the junction of GRIN lens 2284 and low-index polymer material 2286. This partial reflection 2292 can result in a low RL in the range of −35 dB to −60 dB. However, as the reflected beam returns toward optical fiber 2282, it is not refocused back into fiber core 2294, resulting in a low and lossy, ineffective RL of the reference signal. When the reflective reference is configured such that the GR length focuses the beam, it is centered away from the maximum of the optimal GR length for beam collimation, resulting in unpredictable RL and lower manufacturability.

[0117] The GRIN lenses in the example OCT imaging systems described herein may be coated or uncoated and may have lengths in the ranges of 500 μm to 700 μm, 600 μm to 800 μm, 700 μm to 1,100 μm, or 800 μm to 5,000 μm, diameters in the ranges of 65 μm to 130 μm, 100 μm to 200 μm, or 125 μm to 500 μm, and pitch lengths of 0.500 mm to 1,200 mm, 0.600 mm to 1,500 mm, or 0.700 mm to 2,000 mm (e.g., at wavelengths in the ranges of 750 nm to 1,380 nm).

[0118] The reflector 2206 may have a mechanically and / or electrically polished surface, typically oriented at a 45-degree angle relative to the longitudinal axis of the optical fiber. The angle may be carefully varied from 35 to 65 degrees. The reflector 2206 may have layers of gold, silver, tin, nickel-chromium, aluminum, dielectric, or multilayer dielectric or other coatings, and the coating process may involve chemical vapor deposition, physical vapor deposition, sputtering, electroplating, or the like. The coating thickness may be 50 nm to 300 nm, or 100 nm to 250 nm, or 100 nm to 200 nm. The base material for the reflector may be optical glass, ceramic, semiconductor material, or polymer.

[0119] 24 depicts another embodiment of an OCT imaging system 2400 in which an optical fiber 2402 comprises an angled, cleaved or configured distal end or surface 2404 with a surface angle that is not orthogonal to the longitudinal axis of the fiber 2402, but instead is angled at least 8, 10, 12, 15, or more degrees from the orthogonal orientation, which may reduce or eliminate reflection artifacts. A spherical or aspheric lens 2406 may be spaced from the distal surface 2404 of the optical fiber 2402 to receive and collimate the light beam 2408. The light beam 2408 then continues through a low refractive index material 2410 and is reflected by a mirror or reflector 2412 out of the material 2410 and out of the imaging system 2400. The spherical or aspherical lens 2406 may have a refractive index in the range of 1.50 to 1.85 and have a plano-convex configuration with a convex proximal surface 2414 and a flat distal surface 2416, e.g., with a radius of curvature in the range of 0.20 to 1.00 mm. The RL or reference signal at the interface between the lens and the polymer material 2410 may be in the range of -14 dB to -40 dB, or -15 dB to -35 dB, or -20 dB to 35 dB, or -25 dB to -35 dB. The cavity or space between the fiber 2402 and the lens 2406 may be filled with the same material 2410 or a different material, e.g., a polymer material with a higher refractive index in the range of 1.45 to 1.48, 1.40 to 1.50, or 1.5 to 1.85, or a lower refractive index material with a different refractive index in the range of 1.30 to 1.48. The refractive index of the material in the space between the fiber 2402 and the lens 2406 is lower than that of the lens 2406. The spacing between the end of the optical fiber and the lens may be, for example, in the range of 0.1 mm to 4.0 mm, or 0.3 mm to 3.0 mm, or 0.5 mm to 2.00 mm. The spacing between the distal surface of the lens and the center of the reflector may be, for example, in the range of 0.025 mm to 0.250 mm, 0.050 mm to 0.500 mm, 0.1 mm to 3.0 mm, or 0.2 mm to 2.0 mm, or 0.3 mm to 2.00 mm.

[0120] FIG. 25 depicts another variation of an OCT imaging system 2500, similar to the OCT imaging system 2400 of FIG. 24, except that a bi-convex lens 2502 is provided instead of a plano-convex lens. The radius of curvature of the proximal convex surface 2504 may also be in the range of 0.20 mm to 1.00 mm, and the refractive index may be in the range of 1.50 to 1.85. In this particular example, the lens 2502 may include a lens tilt 2506 in the range of 0.10 degrees to 2.00 degrees. The tilt minimizes or eliminates reflection artifacts by deflecting any interface reflections from the lens 2502 away from the optical fiber. In this embodiment, the reflection loss or reference signal collected from the interface between the optical fiber and the polymer material between the optical fiber and the lens 2502 is in the range of -14 dB to -40 dB, or -15 dB to -35 dB, or -20 dB to 35 dB, or -25 dB to -35 dB. The lens 2502 may be configured to provide a non-collimated light beam 2508, or a collimated light beam, as depicted in Figure 25. For non-collimated embodiments, the focal length of the OCT system may be between 0.250 mm and 4.00 mm from the longitudinal axis of the OCT imaging system 2500 or the center of the mirror or reflector 2510.

[0121] 26A and 26C depict additional exemplary embodiments of OCT imaging systems 2600, 2650 in which a Fresnel lens 2602 is provided instead of a GRIN lens or spherical / aspherical lens. The Fresnel lens 2602 may be configured with a grating or diffractive pattern that is optically equivalent to a convex lens with a radius of curvature of 0.20 mm to 1.00 mm. As in some other embodiments described herein, the Fresnel lens 2602 may be spaced from the ends 2604, 2652 of the optical fibers 2606, 2654 within a range of, for example, 0.1 mm to 4.00 mm, 0.2 mm to 3.00 mm, or 0.5 mm to 2.5 mm. The gap or cavity 2608, 2656 between the ends 2604, 2652 of the optical fibers 2606, 2654 and the Fresnel lens 2602 may be filled with a polymer material 2608, 2656. In some further variations, the polymer material 2608, 2656 may be a low refractive index material, for example, n<1.50 or in the range of 1.30-1.48. The polymer material 2610 between the lens 2602 and the reflector 2612 may be in the range of 1.30-1.40, or 1.30-1.48, or 1.30-1.30, or 1.32-1.38, and may be the same or different from the proximal polymer material 2608, 2656. In some variations, the polymer material 2610 may have a higher refractive index, in the range of 1.50-1.70, or 1.52-1.65. The interface between the optical fiber 2606, 2654 and the proximal polymer material 2608, 2656 may be flat or at a 90-degree angle, as depicted in FIG. 26A. It may also be offset from the 90-degree angle, e.g., at least 8, 10, 12, 15, or more degrees from an orthogonal orientation, as depicted in FIG. 26C. FIG. 26A depicts an embodiment with a RL or reference signal from the interface 2604 within the range of -14 dB to -40 dB, or -15 dB to -35 dB, or -20 dB to 35 dB, or -25 dB to -35 dB. The refractive indices of the Fresnel lens and the distal polymer material 2610 are preferably matched or similar.FIG. 26C depicts an embodiment with an RL or reference signal from the interface between the Fresnel lens and a distal polymer material 2610. The refractive index of the distal polymer material 2610 is preferably mismatched or different such that the RL is within the range of -14 dB to -40 dB, or -15 dB to -35 dB, or -20 dB to 35 dB, or -25 dB to -35 dB. FIG. 26B depicts an exemplary Fresnel lens 2602 that may be used in the OCT imaging systems in FIGS. 26A and 26C. The lens 2602 may comprise a circular lens body with multiple gratings or gratings 2660. In this particular embodiment, the lens 2602 is radially symmetric about a first axis 2662 and a second axis 2664 of the lens 2602, both of which are transverse to the longitudinal axes of the optical fibers 2606, 2605 and orthogonal to each other. However, in other variations, the configuration of the diffraction grating pattern may differ along the two axes 2662, 2664 to produce variable focusing power or a combination of beam focusing and collimation. This may be provided to adjust the beam profile and ensure a confocal beam without requiring the use of anamorphic lenses.

[0122] In yet another embodiment, depicted in FIG. 27A , an OCT imaging system 2700 may lack a lens but include a reflector 2702 with a Fresnel diffraction grating formed or etched on its reflective surface. Like the mirrors or reflectors described herein, the Fresnel reflector 2702 may include layers of gold, silver, tin, nickel chromium, aluminum, dielectric, or multilayer dielectric or other coatings. Between the distal end 2704 of the optical fiber 2706 and the Fresnel reflector 2702, a low refractive index polymer 2708, as described herein, may be provided as described elsewhere herein. As the light beam 2710 exits the fiber 2706 and travels through the polymer material 2708, it is reflected and collimated by the diffraction pattern of the Fresnel reflector 2702 and then exits the polymer material 2708 to the target imaging location. The Fresnel reflector 2702 may be configured with an equivalent radius of curvature (R) in the range of -0.25 mm to -2.00 mm (concave) or -0.20 mm to -1.00 mm (concave), a pitch frequency (pitch / mm) of 20 or greater, an optically rotatory pitch angle in the range of 0 to 75 degrees, and a focal length (f) between the fiber and the reflector surface in the range of 200 μm to 1,000 μm. Reflector 2702, as illustrated in FIG. 27F, like the Fresnel lens in FIG. 26B, may comprise a circular reflector body with a plurality of concentric circular gratings, gratings, or diffraction patterns 2760. In this particular embodiment, the reflector 2702 is radially symmetric about the major and minor axes 2762 and 2764 of the reflector 2702; however, in other variations, the configuration of the grating pattern may differ along the two axes 2762, 2764, as discussed below. The orientation of the major axis 2762 is coplanar with the longitudinal axis of the optical fiber 2706 and the reflected beam 2712, while the minor axis 2764 is transverse and perpendicular to the major axis 2762 and the longitudinal axis of the optical fiber 27. This may be provided to adjust the beam profile and ensure a confocal beam or beam waist without requiring the use of an anamorphic lens with a concave reflective surface.In one embodiment of Fresnel reflector 2702, a diffraction grating pattern imprinted on the flat surface, with parameters including, but not limited to, non-optical pitch angle and pitch frequency, may be gradually varied from major axis 2762 to minor axis 2764 to ensure a confocal beam waist. In yet another embodiment of Fresnel reflector 2702, the diffraction grating pattern imprinted on the flat surface may appear asymmetric and elliptical, with the major axis of the elliptical pattern aligned with major axis 2762 and the minor axis of the elliptical pattern aligned with minor axis 2764 aligned to the cross section of the incident beam 2710 within Fresnel reflector 2702.

[0123] Figures 27B-27E depict various cross-sectional beam profiles of the light beam 2710 in Figure 27A. Figures 27B and 27C depict beam profiles 2712, 2714, respectively, at a focal length (fiber-to-reflector surface distance) of 200 μm and a radius of curvature of -0.4 mm (concave), and at a focal length of 250 μm and a radius of curvature of -0.5 mm (concave). Figure 27D depicts beam profile 2716 at a focal length of 300 μm and a radius of curvature of -0.6 mm, while Figure 27E depicts beam profile 2718 at a focal length of 500 μm and a radius of curvature of -1.1 mm.

[0124] 28A depicts another embodiment of an OCT imaging system 2800 that includes both a GRIN lens 2802 and a Fresnel reflector 2804. In this example, a light beam 2814 exiting an optical fiber 2806 is collimated by a GRIN lens 2802, then enters a low refractive index polymer material 2808, and then exits the low refractive index polymer material 2808 and is reflected by a Fresnel reflector 2804 before reaching the target location. As described in other embodiments herein, the end 2812 of the optical fiber 2806 may be a flat surface with a 90 degree orientation relative to the longitudinal axis of the fiber 2806, or may be offset. The collimated light beam 2816 may have a diameter in the range of 20 μm to 200 μm, and the RL at the interface between the GRIN lens 2802 and the low index material may be in the range of −14 dB to −28 dB, −14 dB to −40 dB, or −15 dB to −35 dB, or −20 dB to 35 dB, or −25 dB to −35 dB.

[0125] Depending on the desired configuration, the Fresnel reflector 2804 may be configured with an equivalent radius of curvature in the range of -0.25 mm to -30 mm to provide a focused beam, or in the range of -30 mm to -infinity for a collimated beam. As described above, the diffraction pattern of the Fresnel reflector 2804 may be configured with a radially symmetric or asymmetric pattern. Whether the light beam from the GRIN lens is converging, diverging, collimated, or properly collimated, a Fresnel reflector 2702 or 2804 positioned at 45 degrees as depicted in FIGS. 27A and 28A will introduce astigmatism and exhibit a deviation or offset in beam focusing or combined beam collimation / focusing along the major axis 2762 and minor axis 2764. In variations where some correction for an astigmatic light beam is desired, an elliptical or asymmetric diffraction pattern may be provided. Depending on the axis of astigmatism, the major or minor axis of the Fresnel reflector 2804 may be adjusted to compensate for the astigmatism and provide an elliptical diffraction pattern to match the incident beam at a 45-degree tilt of the reflector 2804. Figures 28B and 28C are schematic side and end views of the reflector 2804 and the profile of the reflected light beam 2816, with an example astigmatic beam profile 2818 depicted in Figure 28D. To compensate for the asymmetric profile 2818, the major 2762 and minor 2764 axes of the reflector 2702 may be adjusted to an elliptical shape to compensate for any astigmatism in the incident beam, such that the reflected beam would be confocal if it were a fully collimated or focused beam, as depicted in Figure 27F. Alternatively, a diffraction grating pattern imprinted on a flat surface, with parameters including, but not limited to, non-optical pitch angle and pitch frequency, may be gradually varied from major axis 2762 to minor axis 2764 to ensure a confocal beam waist. The use of Fresnel reflectors 2702 or 2804 avoids the need for anamorphic lenses with concave reflective surfaces.

[0126] 10 depicts another variation of an imaging intersection device 1000, similar to device 900, except that the optical element 1002 comprises a tapered distal end 1004 with an enlarged diameter body 1006 exterior to a hypotube 1008, and a smaller diameter proximal stem 1010 with a proximal reflective surface 1012. The proximal reflective surface 1012 may be angled off 45 degrees, such as at 45 degrees, or 48 degrees, but not more than 45 + / - 5 degrees. Similar to device 900, a hypotube 1014, an optical fiber 1016, a lens 1018, and an adhesive 1020 are provided.

[0127] 11 depicts yet another embodiment of an imaging intersection device 1100 in which an optical element 1102 comprises a proximal angled surface 1104 on a stem 1106 of an enlarged cutting head 1108, but additionally, a prism 1110 is inserted between a lens 1112 and the proximal angled surface 1104. The prism 1110 comprises an orthogonal proximal surface 1114 optically coupled to the lens 1112 and a 45-degree angled distal end 1116 bonded to the proximal angled surface 1104 of the stem 1106, the prism having a longest dimension of 255 μm or less. The angled distal end (or hypotenuse) 1116 of the prism 1110 may be coated or bonded to the stem 1106 using an aluminum or other metallic reflective coating.

[0128] In use, the imaging crossing device described herein may be used within a conventional guiding catheter to access a desired target location for diagnostic assessment and / or therapeutic treatment. In another variation of the imaging crossing device, a dual-lumen guide catheter may be used. Referring to FIG. 12A, a guide catheter 1200 may include a proximal hub 1202, a catheter body 1204, and a distal tip 1206. Referring to FIG. 12B, the proximal hub 1204 may include one or more proximal openings 1206 that communicate with two or more catheter body lumens 1208, 1210 of the catheter body 1204. As depicted in FIG. 12B, the catheter body 1204 is located partially inside a distal lumen 1212 and a distal opening 1214 of the hub 1202. The hub may further include an optional flush port 1216, which may be configured to be in fluid communication with one or both of the catheter body lumens 1208, 1210. In some variations, the catheter body 1204 may include a separate tubular body for each catheter body lumen 1208, 1210, which is located inside the overtube 1218, as depicted in FIG. 12B. In these variations, the flush port may be in fluid communication with the tubular lumen of the overtube 1218 but is outside the catheter body lumens 1208, 1210. The catheter lumens 1208, 1210 may have the same or different diameters. In the particular example depicted in FIG. 12B, the catheter lumen 1208 includes a smaller diameter of 0.016 inches for use with a guidewire, and the catheter lumen 1210 includes a larger diameter of 0.022 inches or 0.025 inches to receive an imaging crossing device. 13 and 14, which depict variations of the distal embodiment of dual lumen guide catheters 1300 and 1400, the last 2 to 6 inches (50.8 to 152.4 mm) of the distal end comprise an optically transparent material. In another embodiment, the last 3 to 5 inches (76.2 to 127.0 mm) of distal end 1300 and 1400 comprise an optically transparent material.

[0129] The distal end 1220 of the catheter body 1204 may be attached to a catheter tip 1220. Referring to Figure 15, the catheter tip 1220 may include a cylindrical base 1222 with a proximal surface 1224 and corresponding openings for tip lumens 1226 and 1228 configured to be in fluid communication with the catheter body lumens 1208 and 1210. In this particular catheter tip 1220, the tip lumen 1226 extends distally from the proximal surface 1224 along an extension tube 1230 that projects distally from the cylindrical base 1222 a greater distance than the tip lumen 1228. One or more angled transition surfaces 1232 may be provided on the outer surface of the cylindrical base 1222 to provide a smooth transition from the extension tube 1230.

[0130] In some variations of guide catheters used in conjunction with an imaging crossing device, one or more side openings along the catheter body and / or catheter tip may be provided so that the guidewire can be manipulated to exit the guide catheter proximally relative to the distal opening 1334 of the guidewire tip lumen 1228. In Figure 16, for example, a side opening 1602 is provided in the catheter tip 1600. This may be in addition to catheter body openings provided, for example, at 20 cm, 40 cm, and / or 60 cm distances along the catheter body, as measured from the hub.

[0131] 15 and 16, in some variations, the guidewire tip lumens 1226 and 1604 may have a generally linear configuration, with the lumens extending axially without any angle or deviation from the longitudinal axis. However, in other embodiments, or with respect to the imaging crossing device tip lumens 1228 and 1606, the lumens 1228 and 1606 may include an angled region to direct an inserted device at an outward angle away from the extension tube 1230. This may be useful to facilitate diagnosis or treatment of eccentric anatomical lesions. However, in other embodiments, the lumens 1228 and 1606 may have a linear orientation.

[0132] 13 and 14 depict additional features of guide catheters 1300 and 1400, which may include radiopaque marker bands 1302 and 1402, respectively, located along catheter bodies 1304 and 1404. Marker band 1302 comprises a ring-like configuration with a uniform length, while marker band 1402 comprises an asymmetric configuration, which may facilitate assessment of catheter orientation and / or location.

[0133] The operation of an optical system is generally described in terms of light emitted by the optical system toward a target area. However, those skilled in the art will understand that because optical paths may typically be reversible, a beam path may also represent the field of view "seen" by the optical system (e.g., reaching the receiving portion of the optical system). Thus, an imaging beam emitted by an optical fiber may also represent (all or part of) the path along which light received may return to the fiber.

[0134] Certain materials are described herein based on their interaction with light (e.g., opaque, reflective, transmissive, refractive, etc.). These descriptors may refer to the material's interaction with the range of wavelengths emitted by the system and / or to which its light receiver is sensitive. Those skilled in the art will understand that the properties of a given material vary over different wavelength ranges, and different materials may be desirable for different wavelength ranges. The description of specific example materials is not intended to limit the disclosure to the range of wavelengths over which the particular example material has desired optical properties. Similarly, the description of specific wavelengths is not intended to limit the system to only those wavelengths. The term "light" may be used throughout the spectrum to refer to electromagnetic radiation and is not intended to limit the disclosure to electromagnetic radiation within the visible spectrum. The term "light" may refer to electromagnetic radiation of any wavelength.

[0135] Of course, it should be understood that any one of the examples, embodiments, or processes described herein may be combined with one or more other examples, embodiments, and / or processes, or separated and / or implemented among separate devices or device portions, in accordance with the present systems, devices, and methods.

[0136] Finally, the above discussion is intended to be merely illustrative of the present system and should not be construed as limiting the appended claims to any particular embodiment or group of embodiments. Accordingly, while the present system has been described in particular detail with reference to exemplary embodiments, it should also be understood that numerous modifications and alternative embodiments may be devised by those skilled in the art without departing from the broader intended spirit and scope of the present system, as set forth in the following claims. Accordingly, the specification and drawings are to be regarded in an illustrative manner and are not intended to limit the scope of the appended claims.

Claims

1. An imaging device, an outer shaft with a lumen; an optical fiber located within the lumen of the outer shaft; a reflective element disposed within the lumen of the outer shaft, the reflective element comprising an optical material with an angled surface configured with respect to an imaging beam; a first optical filler between the distal end of the optical fiber and the reflective element, the first optical filler having a refractive index less than 1.40; and a lens positioned between the optical fiber and the reflective element; and optionally the lens is a Fresnel lens, a plano-convex lens, or a bi-convex lens; The imaging device, wherein the lens is tilted at 0.1 to 2.0 degrees.

2. An imaging device, an outer shaft with a lumen; an optical fiber located within the lumen of the outer shaft; a reflective element disposed within the lumen of the outer shaft, the reflective element comprising an optical material with an angled surface configured with respect to an imaging beam; a first optical filler between the distal end of the optical fiber and the reflective element, the first optical filler having a refractive index less than 1.40; and wherein the reflective element further comprises a tapered distal end protruding from the lumen of the outer shaft, the tapered distal end configured to penetrate tissue.

3. 3. The imaging device of claim 1, wherein the refractive index of the first optical filler is in the range of 1.30 to 1.40 or 1.33 to 1.

38.

4. the first optical filler comprises an aliphatic urethane acrylate and an acrylic monomer; 3. The imaging device of claim 1, wherein optionally the aliphatic urethane acrylate constitutes 30% to 70% of the first optical filler and the acrylic monomer is 70% to 30% of the first optical filler, or optionally the aliphatic urethane acrylate constitutes 40% to 65% of the first optical filler and the acrylic monomer is 60% to 35% of the first optical filler.

5. The imaging device of claim 4 , wherein the viscosity of the first optical filler material is in the range of 1,000 to 3,000 cps, 1,500 to 3,000 cps, or 2,000 to 2,500 cps.

6. 2. The imaging device of claim 1, wherein the lens is a GRIN lens, optionally a beam-collimating GRIN lens, optionally having a pitch of at least 0.75 or greater within a unit length, and having a reflection artifact stronger than −40 dB at an interface between the optical fiber and the GRIN lens.

7. The imaging device of claim 6 , further comprising an uncladded fiber followed by the GRIN lens between the optical fiber and the reflective element.

8. The imaging device of claim 1 , wherein the first optical filler is further located between the lens and the reflective element.

9. a second optical filler positioned between the optical fiber and the lens; 10. The imaging device of claim 1, wherein the first optical filler and the second optical filler comprise different materials, or the first and second optical fillers comprise components that are the same but in different ratios, and both the first and second optical fillers have a refractive index less than 1.

50.

10. The imaging device of claim 1 or claim 2, wherein the angled surface of the reflective element comprises a Fresnel diffraction pattern.

11. 11. The imaging device of claim 10, wherein the Fresnel diffraction pattern has different collimating or focusing power along its major axis, minor axis, and between the major axis and the minor axis, or wherein the imaging device further comprises a lens located between the optical fiber and the reflective element, the lens optionally being a GRIN lens.

12. The imaging device of claim 11 , wherein the first optical filler is located between the lens and the reflective element.

13. 3. The imaging device of claim 1, wherein a collimating lens is located between the optical fiber and the first optical filling material, and the collimating lens is a GRIN lens and a plano-convex, or bi-convex or Fresnel lens.

Images