JP2011056165A - Oct system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an OCT (Optical Coherence Tomography) system, obtaining an accurate tomographic image having a large width of depth without any increase in the length of a hard part of the tip of an OCT probe. <P>SOLUTION: This OCT system includes: a plurality of optical fibers; the OCT probe having GRIN lenses provided at each tip side of the optical fibers and micro mirrors provided at the tip side of each GIN lens; and a distributing and condensing device for distributing the light from a low-coherence light source of the OCT system to the plurality of optical fibers and condensing the return light from the optical fibers and transmitting the same to an interferometer of the OCT system. The respective micro mirrors are disposed on one plane perpendicular to the axis of rotation of the OCT probe to bend the light emitted from the optical fibers outwardly in the radial direction of a circle around the center of the axis of rotation, and the light emitted from the plurality of optical fibers is different in distance of the condensing point to the center of rotation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an OCT system that calculates an OCT tomographic image near the tip of an optical fiber by rotating an optical fiber inserted in a sheath with a closed end and scanning around the axis of the optical fiber.

  In recent years, an optical coherence tomography (OCT) system that measures a tomographic image using low-coherence light has been put into practical use and is being used. In the OCT system, low coherence light is irradiated to a living tissue. Based on the principle of the Michelson interferometer, how much this light is reflected or scattered at which position in the living tissue is measured, and a tomographic image of the living tissue is created by calculation based on this measurement result. is there.

When acquiring a tomographic image in a body cavity by the OCT system, an OCT probe is inserted into the body cavity. An example of a general OCT probe is shown in FIG. As shown in FIG. 6, a general OCT probe 110 has an optical fiber 111 provided with a condenser lens 112 and a deflecting element 113 at the tip. Incident light LCL _i that is low-coherence light is incident on the proximal end side of the optical fiber 111, and this incident light LCL _i reaches the distal end through the optical fiber 111, and is bent by approximately 90 ° by the deflecting element 113. Irradiation toward the wall surface CS.

The low coherence light used in the OCT system has a property of transmitting through the living body such as near infrared rays. Incident light LCL _i towards the wall of the body cavity CS from the deflecting element 113 is reflected or scattered by the body tissue in the body cavity wall, this part of the return light LCL _o returned to the optical fiber 111 is reflected again by the deflecting element 113 Become. OCT system, by using a low coherence light source and a Michelson interferometer, the return light LCL _o propagation distance the light intensity for the (optical path length) of the measures as an interference signal, how much the incident light LCL _i at any position from the measurement result It is possible to calculate whether the light is reflected or scattered.

The condensing lens 112 is disposed between the optical fiber 111 and the deflection element 113 and condenses incident light LCL _i at a predetermined depth. Incident light LCL _i is strongly reflected or scattered near the condensing point P by the condensing lens 112, and the OCT system is within a predetermined depth width (about several hundreds of micrometers) near the condensing point P. A strong interference signal can be obtained.

  Further, as shown in FIG. 6, the OCT probe 110 is driven to rotate around the axis of the optical fiber 111, and the OCT system can obtain a tomographic image of the cross section SF of the body cavity at the position where the deflection element 113 is located. it can.

  Thus, a tomographic image of a tubular living body such as a digestive organ or a circulatory organ can be obtained by the OCT system. However, as described above, the width of the depth at which a clear tomographic image is obtained is as small as several hundred micrometers.

  In order to solve this problem, a configuration as described in Patent Document 1 has been proposed. In the configuration of Patent Document 1, the OCT probe has a plurality of optical fibers sharing a single deflection element (mirror) and a condenser lens. The distance between the tip of the optical fiber and the condensing lens is different for each optical fiber, and the incident light passing through each optical fiber is collected at different depths. For this reason, the width of the depth from which a clear tomographic image can be obtained in the entire OCT probe can be widened.

Special table 2004-502957

  As described above, in the OCT system described in Patent Document 1, it is possible to obtain a tomographic image having a wide depth. However, such a configuration needs to be fixed so that the distance between the tip of each optical fiber and the condenser lens does not fluctuate. For this reason, a comparatively long hard part is formed in the front-end | tip part of an OCT probe. Since such an OCT probe lacks flexibility, it is not easy to insert it into a body cavity.

  Further, in the OCT system described in Patent Document 1, since the focusing position of each optical fiber is shifted not only in the depth but also in the surface direction of the body cavity wall surface, an accurate tomographic image is always obtained. It wasn't.

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide an OCT system capable of obtaining a tomographic image with a large depth width without increasing the length of the hard portion at the tip of the OCT probe.

  In order to achieve the above object, an OCT system of the present invention is provided with a plurality of optical fibers, a condensing lens provided on the base end side of each of the plurality of optical fibers, and a tip side of each of the plurality of optical fibers. A plurality of GRIN lenses and a plurality of micromirrors provided on the tip side of the plurality of GRIN lenses, and a plurality of light from a low-coherence light source of the OCT system via a plurality of condensing lenses. And a distribution concentrator that collects the return light from the plurality of optical fibers and sends it to the interferometer of the OCT system, and each of the micromirrors is disposed on the central axis of rotation of the OCT probe. Bending light emitted from a plurality of optical fibers arranged on one vertical plane outward in the radial direction of a circle centered on the rotation center axis on the one plane; Distance to the rotational center of the focal point of the light emitted from the number of optical fibers different from each other.

  According to the above configuration, fixing the relative position so as not to move is limited to a portion having a relatively small length from the tip of the optical fiber to the micromirror. For this reason, the size of the hard portion at the tip of the OCT probe is small, and the OCT probe is excellent in flexibility. Moreover, according to said structure, the light radiate | emitted from several optical fiber is bent by each micromirror, and advances on one plane perpendicular | vertical to a rotation center axis. For this reason, the tomographic image formed by the light supplied to each optical fiber becomes a tomographic image on the same plane.

  Also, the length of the plurality of optical fibers is such that the difference in optical path length from the plurality of condensing lenses to each of the condensing points of light emitted from the plurality of optical fibers is larger than the observation depth in each optical fiber. It is preferable to adopt a configuration that is set to be sufficiently large.

  With such a configuration, interference signals measured from low-coherence light passing through a plurality of optical fibers do not overlap in different ranges of optical path lengths, and a tomographic image is obtained separately from each optical fiber.

  Further, the plurality of GRIN lenses may have the same optical characteristics, and the plurality of micromirrors may be arranged on a plurality of circles having different radii with respect to the rotation center axis.

  Here, the OCT probe may have an optical filter for transmitting only light in different wavelength ranges to the optical fibers.

  With such a configuration, since each of the plurality of optical fibers separately forms an interference signal in a different wavelength region, a tomographic image in a different wavelength region can be obtained separately from the interference signal.

  Further, instead of a configuration in which the plurality of micromirrors are arranged on a plurality of circles having different radii with respect to the rotation center axis, respectively, between the plurality of micromirrors and the plurality of tip side optical fibers, respectively. A plurality of GRIN lenses having different focal lengths may be arranged, and the plurality of micromirrors may be arranged on the same circle around the rotation center axis of the OCT probe.

  In addition, the OCT system is a probe in which light from a low coherence light source is incident to guide the light from the low coherence light source to a distribution concentrator and return light from a plurality of optical fibers is input to guide the return light to an interferometer. And a distribution concentrator is provided between the probe optical fiber and the plurality of condensing lenses, and sends the light from the low coherence light source in parallel to the plurality of condensing lenses. A fixed lens that collects the return light from the plurality of optical fibers and makes it incident on the optical fiber for the probe, and the plurality of condensing lenses are on the same circumference around the optical axis of the fixed lens. It is preferable to adopt a configuration in which they are arranged.

  With such a configuration, light from the low-coherence light source can be distributed to each optical fiber substantially evenly.

  As described above, according to the present invention, an OCT system capable of obtaining a tomographic image with a large depth width without increasing the length of the hard portion at the tip of the OCT probe is realized.

FIG. 1 is a block diagram of an OCT system according to a first embodiment of this invention. FIG. 2 is a perspective view of the rotary joint according to the first embodiment of the present invention. FIG. 3 is a perspective view of the distal end portion of the OCT probe according to the first embodiment of the present invention. FIG. 4 is a view of the OCT probe according to the first embodiment of the present invention viewed from the distal end side. FIG. 5 is a view of the OCT probe according to the second embodiment of the present invention as viewed from the distal end side. FIG. 6 is a diagram showing a configuration of a general OCT probe.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the overall structure of an OCT system which is a tomographic image acquisition apparatus using OCT according to the first embodiment of the present invention. The OCT system 1 according to the present embodiment includes an OCT probe 10, an optical drive unit 20, a probe interface unit 30, and a display unit 40. In FIG. 1, the path of the electric signal is indicated by a two-dot chain line, the optical path by the optical fiber is indicated by a solid line, and the optical path of light traveling in the air or in the living tissue is indicated by a broken line. In the following description, the direction of the optical path approaching the light source of the OCT system 1 is defined as the base end side, and the direction away from the light source is defined as the distal end side.

  As shown in FIG. 1, the probe interface unit 30 connects an optical fiber bundle 11 of the OCT probe 10 and a probe optical fiber 22 extending from the fiber interferometer 21 of the optical drive unit 20 to the outside of the optical drive unit 20. Is.

  The optical fiber bundle 11 includes, for example, five tip-side optical fibers 11Ta to 11Te (only one is shown in the drawing) in a resin tube made of polytetrafluoroethylene or the like having five holes in the axial direction. It is inserted through the hole and optically connected to the probe optical fiber 22 by the rotary joint 31. The optical fiber bundle 11 may have a configuration other than this.

  As shown in FIG. 2, the rotary joint 31 is used for the probe while maintaining the state in which the optical fiber bundle 11 of the OCT probe 10 and the optical fiber for probe 22 on the optical drive unit 20 side are optically connected. The optical fiber bundle 11 is rotatably held with respect to the optical fiber 22. The rotary joint 31 distributes the low coherence light supplied from the low coherence light source 23 via the probe optical fiber 22 to the rotary joint 31 so as to be incident on the distal end side optical fibers 11Ta to 11Te, and the distal end side light. It has a function as a distribution condenser which collects the return light from the fibers 11Ta to 11Te and returns it to the probe optical fiber 22.

  The probe interface unit 30 includes a motor 32. A rotation shaft (not shown) of the motor 32 is configured to be engageable with the proximal end portion of the optical fiber bundle 11 on the OCT probe 10 side in the rotary joint 31. Therefore, the optical fiber bundle 11 including the optical fibers 11Ta to 11Te is integrally formed around the long axis of the optical fiber bundle 11 by engaging the rotation shaft of the motor 32 with the optical fiber bundle 11 and then driving the motor 32. Can be rotated.

  A specific configuration of the rotary joint 31 will be described below. FIG. 2 is an enlarged view of the rotary joint 31 of the present embodiment. As shown in FIG. 2, the rotary joint 31 includes a fixed lens 31 a and a bearing 31 b that rotatably supports the proximal end portion of the optical fiber bundle 11. The fixed lens 31a, the tip 22a of the probe optical fiber 22, and the bearing 31b are fixed to a frame (not shown) of the probe interface unit 30.

  The fixed lens 31a collects parallel light emitted from the proximal end side of the distal end side optical fibers 11Ta to 11Te and the function as a collimating lens for making the light emitted from the distal end portion 22a of the probe optical fiber 22 into parallel light. It functions as a condensing lens that returns light to the probe optical fiber 22. The optical axis of the tip 22a of the probe optical fiber 22 substantially coincides with the optical axis of the fixed lens 31a.

  The bearing 31b supports the proximal end portion of the optical fiber bundle 11 so as to be rotatable around the distal end portion 22a of the probe optical fiber 22 and the optical axis X of the fixed lens 31a. Condensing GRIN lenses 14a to 14e are provided on the proximal ends of the distal end side optical fibers 11Ta to 11Te, respectively. The condensing GRIN lenses 14a to 14e condense parallel light incident from the fixed lens 31a side so as to be incident on the distal end side optical fibers 11Ta to 11Te, and to emit light emitted from the distal end side optical fibers 11Ta to 11Te. In this case, the light is incident on the fixed lens 31a. Note that the optical axes of the condensing GRIN lenses 14a to 14e are substantially parallel to the tip 22a of the probe optical fiber 22 and the optical axis X of the fixed lens 31a.

  Further, as shown in FIG. 2, the condensing GRIN lenses 14a to 14e are arranged on the same circumference centered on the optical axis X of the distal end portion 22a of the probe optical fiber 22 and the fixed lens 31a. . Therefore, the amount of light incident on the condensing GRIN lenses 14a to 14e from the distal end portion 22a of the probe optical fiber 22 is substantially equal.

  As shown in FIG. 1, a plurality of micromirrors 13 a to 13 e (only one is shown in FIG. 1) are fixed to the tips of the optical fibers 11 Ta to 11 Te of the optical fiber bundle 11 of the OCT probe 10. Yes. The micromirrors 13a to 13e bend the light emitted from the distal end side optical fibers 11Ta to 11Te by about 90 ° and irradiate the tissue T in the lumen near the distal end portion of the OCT probe 10 and the inside of the tissue T in the lumen. The light reflected or scattered by is bent again and returned to the tip side optical fibers 11Ta to 11Te. The micromirrors 13a to 13e are integrated with the corresponding front end side optical fibers 11Ta to 11Te. When the optical fiber bundle 11 is rotated by the motor 32, the direction of light emitted from the micromirrors 13a to 13e is changed to the micromirror. It fluctuates periodically in a plane that intersects with 13a to 13e and is perpendicular to the axis of each of the distal end side optical fibers 11Ta to 11Te. That is, by driving the motor 32, circumferential scanning can be performed.

  The optical drive unit 20 includes a low-coherence light source 23, a fiber interferometer 21, a signal processing circuit 24, a supply optical fiber 25, a reference optical fiber 26, a lens 27, and a roof mirror 28. The low coherence light supplied to the optical fiber bundle 11 of the OCT probe 10 is generated by the low coherence light source 23. The low coherence light generated by the low coherence light source 23 is first sent to the fiber interferometer 21 via the supply optical fiber 25. The fiber interferometer 21 divides low-coherence light supplied using an optical coupler or the like into two light beams, one of which is sent as object light to the probe optical fiber 22, and the other as reference light to the reference optical fiber 26. send.

  As described above, the object light sent to the probe optical fiber 22 is sent to the optical fiber bundle 11 of the OCT probe 10 through the rotary joint 31 of the probe interface unit 30. Then, the object light reflected on the surface or inside of the living tissue T in the lumen returns to the fiber interferometer 21 via the optical fiber bundle 11, the rotary joint 31, and the probe optical fiber 22.

  The reference light sent to the reference optical fiber 26 is emitted from the tip of the reference optical fiber 26 and enters the lens 27. The reference light becomes parallel light by the lens 27. That is, the lens 27 functions as a collimating lens in the forward path. The reference light emitted from the lens 27 is folded back by the roof mirror 28 and enters the lens 27 again. The lens 27 collects the reference light from the roof mirror 28 and makes it incident on the tip of the reference optical fiber 26. That is, in the return path, the lens 27 functions as a condenser lens. Then, the reference light returned to the reference optical fiber 26 returns to the fiber interferometer 21.

  In the fiber interferometer 21, the object light returned from the probe optical fiber 22 and the reference light returned from the reference optical fiber 26 are combined. The low-coherence light supplied by the low-coherence light source is a collection of light of various frequencies, and the interference signal is generated only when the optical path length of the object light matches the optical path length of the reference light. is there. That is, the fiber interferometer 21, the low-coherence light source 23, the supply optical fiber 25, the reference optical fiber 26, the lens 27, the roof mirror 28, the probe optical fiber 22, and the optical fiber bundle 11 of the OCT probe 10 as a whole are Michelson. This constitutes an interferometer.

  The intensity of the interference signal generated in the fiber interferometer 21 is a specific position in the living tissue T corresponding to the position of the roof mirror 28 (the optical path length from this position to the fiber interferometer 21 is determined from the roof mirror 28 to the fiber interferometer 21). This corresponds to the degree of reflection and scattering of object light that occurred in the optical path length up to). Further, the roof mirror 28 is configured to be movable in a direction away from and in contact with the lens 27 (a white arrow portion in FIG. 1). By moving the roof mirror 28, the optical path length of the reference light can be varied. Thereby, the scanning of the living tissue T in the depth direction can be performed.

  As described above, in the OCT system 1 of the present embodiment, scanning in the circumferential direction and the depth direction can be performed, and therefore a series of measurement results of the fiber interferometer 21 obtained by performing scanning are used. By performing numerical calculation, it is possible to calculate and output a tomographic image on a plane that passes through the distal ends of the optical fiber bundles 11Ta to 11Te of the optical fiber bundle 11 of the OCT probe 10 and is perpendicular to the axis of the optical fiber. Specifically, the measurement result by the fiber interferometer 21 is sent to the signal processing circuit 24, and the signal processing circuit 24 performs numerical calculation to create a tomographic image. The generated tomographic image data is sent to the display unit 40. In the present embodiment, the display unit 40 includes a PC 41 connected to the signal processing circuit 24 of the optical drive unit 20 and a monitor 42 connected to the PC 41. The PC 41 displays a tomographic image as an image on the monitor 42. Let

  As described above, by using the OCT system 1 of the present embodiment, a tomographic image of a living tissue can be observed. Note that the low-coherence light source 23 is turned on / off, the motor 32 of the roof mirror 28 and the probe interface unit 30 is driven, and the signal processing circuit 24 is controlled by a controller 29 built in the optical drive unit 20.

  In addition, GRIN lenses 12a to 12e are disposed between the distal end side optical fibers 11Ta to 11Te and the micromirrors 13a to 13e. The GRIN lenses 12a to 12e collect low coherence light emitted from the distal end side optical fibers 11Ta to 11Te at predetermined light condensing positions P1 to P5, respectively. In the present embodiment, the relative positions of the condensing positions P1 to P5 of the low-coherence light emitted from each of the tip end optical fibers 11Ta to 11Te with respect to the rotation center of the optical fiber bundle 11 (that is, the depth of each condensing position). ) Are different from each other. For this reason, the tomographic images by the return light from the distal end side optical fibers 11Ta to 11Te have different depths, and the signal processing circuit 24 combines these tomographic images to obtain a tomographic image having a large depth width. it can.

  In the OCT probe 10 of the present embodiment, a configuration for shifting the condensing position of the low-coherence light from each of the distal end side optical fibers 11Ta to 11Te will be described below. FIG. 3 is a perspective view of the distal end portion of the OCT probe 10 of the present embodiment. FIG. 4 is a front view of the OCT probe 10 of the present embodiment as viewed from the distal end side.

  As shown in FIGS. 3 and 4, in the present embodiment, the distal end side optical fiber 11Ta and the distal end portion of the GRIN lens 12 a are arranged on the rotation center axis A of the OCT probe 10. That is, the optical axis Oa of the distal end side optical fiber 11Ta and the GRIN lens 12a substantially coincides with the rotation center axis A of the OCT probe 10. The distal end side optical fibers 11Tb to 11e are arranged on concentric cylindrical surfaces α, β, γ, and δ with the rotation center axis A as an axis. Similarly, the tip portions of the GRIN lenses 12b to 12e are also disposed on the concentric cylindrical surfaces α, β, γ, and δ. Here, the radii of the concentric cylindrical surfaces α, β, γ, and δ are d, 2d, 3d, and 4d, respectively.

  Further, the distal end portions of the distal end side optical fibers 11Ta to 11Te are all disposed on the same plane perpendicular to the rotation center axis A. The leading ends of the GRIN lenses 12a to 12e are also arranged on the same plane perpendicular to the rotation center axis A.

  The micromirror 13a moves low-coherence light traveling along the optical axis Oa of the distal-end optical fiber 11Ta and the GRIN lens 12a toward one direction on a plane perpendicular to the optical axis Oa (that is, in the radial direction of the OCT probe 10). It is arranged to bend (towards the outside).

  Further, the micromirrors 13b to 13e respectively transmit the low coherence light traveling along the optical axes Ob to Oe of the front end side optical fibers 11Tb to 11e and the GRIN lenses 12b to 12e to radii of concentric cylindrical surfaces α, β, γ, and δ, respectively. It is arranged to bend outward in the direction.

  Since the distal end side optical fibers 11Ta to 11Te, the GRIN lenses 12a to 12e, and the micromirrors 13a to 13e are arranged as described above, the low coherence proceeding along the optical axes Oa to Oe of the distal end side optical fibers 11Ta to 11Te. The light is bent by the micromirrors 13a to 13e, travels on a plane perpendicular to the rotation center axis A, and enters the living tissue T (FIG. 4).

  Here, since the GRIN lenses 12a to 12e have the same structure and optical characteristics, the depths of the condensing points P2, P3, P4, and P5 of the low coherence light supplied to the distal end side optical fibers 11Tb, 11Tc, 11Td, and 11Te. Is deeper by d, 2d, 3d, and 4d than the depth of the condensing point P1 of the low-coherence light supplied to the distal-end optical fiber 11Ta.

  In the OCT system 1 of the present embodiment, the depth width by which the low-coherence light supplied to each of the distal end side optical fibers 11Ta to 11Te can clearly obtain a tomographic image is approximately d. Therefore, a tomographic image having a depth width of 5d can be formed by synthesizing tomographic images formed from the low-coherence lights supplied to the distal end side optical fibers 11Ta to 11Te.

  In the present embodiment, as described above, the distal end portions of the distal end side optical fibers 11Ta to 11Te, the GRIN lenses 12a to 12e, and the micromirrors 13a to 13e are arranged on the same plane, so that the relative position moves. What is fixed so as not to be limited is limited to a portion having a relatively small size in the length direction from the distal end portion of the distal end side optical fibers 11Ta to 11Te to the micromirrors 13a to 13e. For this reason, the size of the hard part at the tip of the OCT probe 10 is small, and the OCT probe is excellent in flexibility.

  Moreover, since each micromirror 13a-13e is arrange | positioned on the same plane perpendicular | vertical to the rotation center axis | shaft A as mentioned above, the tomogram formed by the low coherence light supplied to each optical fiber 11Ta-11Te Are tomographic images on the same plane.

  In addition, in the rotary joint 31, since the return light from each optical fiber 11Ta-11Te is synthesize | combined, the mechanism for isolate | separating and measuring these return light is needed. For example, the tip side optical fiber 11Tb is made longer than the tip side optical fiber 11Ta by a length l sufficiently larger than the observable depth of OCT, and the tip side optical fiber 11Tc is made longer than the tip side optical fiber 11Tb by a length l. Then, if the tip side optical fiber 11Td is made longer than the tip side optical fiber 11Tc by 1 and the tip side optical fiber 11Te is made longer than the tip side optical fiber 11Td by 1, it returns from each tip side optical fiber 11Ta to 11Te. Interference signals generated by the object light and the reference light returned from the reference optical fiber 26 are distributed over a length of 4 l. The interference signals do not overlap each other and separate the interference signals. Can be measured. For example, the observation depth in the OCT observation of the digestive tract mucosa is about 2 mm, and therefore the image display range is often about 4 mm. For this reason, in order to separate and measure the return light from each of the distal end side optical fibers 11Ta to 11Te, l ≧ 4 mm may be set.

  Note that near-infrared light used as low-coherence light for the OCT system has a better resolution in the depth direction as the wavelength is shorter, and tends to enter the living body deeper as the wavelength is longer. By arranging optical filters having different transmission characteristics on the proximal end side of ˜11Te, for example, in front of the condensing GRIN lenses 14a to 14e (FIG. 2), scanning of the distal end side optical fibers 11Ta, 11Tb, etc. can be performed at a small depth. A low-coherence light having a short wavelength (for example, about 800 to 1100 nanometers) is supplied to the tip side optical fiber for performing, while the tip side optical fibers 11Td, 11Te, etc. are used for scanning at a large depth. By supplying low-coherence light with a long wavelength (for example, about 1200 to 1700 nanometers) to the distal end side optical fiber, In can get a good tomographic image with resolution is observable and while small depth. In such a case, the reference light returned from the reference optical fiber 26 includes all low-coherence light having different wavelength ranges, but light having different wavelength ranges does not form an interference signal. With the same configuration as the fiber interferometer 21 (FIG. 1), the return light from each of the optical fibers 11Ta to 11Te can be separated and measured, and the signal processing circuit 24 determines the tomograms at different depths from this measurement result. Form.

  In the first embodiment of the present invention described above, the micromirrors 13a to 13e are arranged on different concentric cylindrical surfaces, but the present invention is not limited to the above-described configuration, and each tip side. Other configurations in which low coherence light passing through the optical fibers 11Ta-11Te is collected at different depths are also within the scope of the present invention. The second embodiment of the present invention described below has a configuration in which micromirrors 13a to 13e are arranged on the same cylindrical surface.

  FIG. 5 shows the OCT probe 10 of the OCT system 1 according to the second embodiment of the present invention as viewed from the tip thereof. As shown in FIG. 5, in the present embodiment, the micromirrors 13 a to 13 e are arranged on a circle ε centered on the rotation center axis A on a plane orthogonal to the rotation center axis A of the OCT probe 10. ing. The micromirrors 13a to 13e are arranged so as to bend the low coherence light passing through the optical axes Oa to Oe of the distal end side optical fibers 11Ta to 11Te toward the radially outer side of the circle ε.

  In the present embodiment, the focal length of the GRIN lenses 16b to 16e disposed at the distal ends of the distal end side optical fibers 11Tb to 11Te is the focal length of the GRIN lens 16a disposed at the distal end of the distal end side optical fiber 11Ta. Rather than d, 2d, 3d and 4d, respectively. For this reason, the condensing points P1 to P5 by the low coherence light supplied to the respective distal end side optical fibers 11Ta to 11Te have different depths. Here, also in the OCT system 1 of the present embodiment, the depth width at which the low-coherence light supplied to each of the distal end side optical fibers 11Ta to 11Te can clearly acquire a tomographic image is approximately d. For this reason, it is possible to form a tomographic image having a depth width of approximately 5d by synthesizing tomographic images formed from the low coherence lights supplied to the distal end side optical fibers 11Ta to 11Te.

  As described above, also in the present embodiment, the distal end portions of the distal end side optical fibers 11Ta to 11Te, the GRIN lenses 12a to 12e, and the micromirrors 13a to 13e are arranged on substantially the same plane, so that the relative position moves. What is fixed so as not to be limited is limited to a relatively short portion from the tip of the tip side optical fibers 11Ta to 11Te to the micromirrors 13a to 13e. For this reason, the size of the hard part at the tip of the OCT probe 10 is small, and since it is excellent in flexibility, it becomes an OCT probe excellent in insertion.

  Also in the present embodiment, since the micromirrors 13a to 13e are arranged on the same plane perpendicular to the rotation center axis A, the micromirrors 13a to 13e are formed by low coherence light supplied to the tip end side optical fibers 11Ta to 11Te. The tomographic image becomes a tomographic image on the same plane.

  In the present embodiment, the distal end portions of the distal end side optical fibers 11Ta to 11Te, the GRIN lenses 12a to 12e, and the micromirrors 13a to 13e are fixed to a guide wire 15 disposed along the rotation center axis A. By using a wire having a high torque transmission rate as the guide wire 15, the optical fiber bundle 11 can be smoothly rotated around the rotation center axis A.

  Since other configurations are the same as those of the OCT system according to the first embodiment of the present invention, detailed description thereof is omitted.

DESCRIPTION OF SYMBOLS 1 OCT system 10 OCT probe 11 Optical fiber bundle 11Ta-11Te Tip side optical fiber 12a-12e GRIN lens 13a-13e Micro mirror 15 Guide wire 31 Rotary joint

Claims (6)

An OCT system for obtaining a tomographic image of a tubular living tissue,
A plurality of optical fibers;
A plurality of condensing lenses provided on the base end side of the plurality of optical fibers;
A plurality of GRIN lenses provided on the tip side of the plurality of optical fibers;
A plurality of micromirrors provided on the tip side of the plurality of GRIN lenses;
An OCT probe having
Light from the low-coherence light source of the OCT system is distributed to the optical fiber via the plurality of condensing lenses, and return light from the plurality of optical fibers is condensed and sent to the interferometer of the OCT system. A distribution concentrator;
Have
The plurality of micromirrors are arranged on a plane perpendicular to the rotation center axis of the OCT probe, and light emitted from the plurality of optical fibers is a circle around the rotation center axis on the plane. Is bent outward in the radial direction of
The OCT system characterized in that the distances of the condensing points of the light emitted from the plurality of optical fibers to the rotation center are different.   The length of the plurality of optical fibers is such that the difference in optical path length from the plurality of condensing lenses to each of the condensing points of light emitted from the plurality of optical fibers is larger than the observation depth by each optical fiber. The OCT system according to claim 1, wherein the OCT system is set to be sufficiently large. The plurality of GRIN lenses have the same optical characteristics;
The OCT system according to claim 1, wherein the plurality of micromirrors are arranged on a plurality of circles having different radii with respect to the rotation center axis.   The OCT system according to claim 3, further comprising a filter for transmitting only light in different wavelength ranges to each of the optical fibers. A plurality of GRIN lenses having different focal lengths are disposed between the plurality of micromirrors and the plurality of optical fibers,
3. The OCT system according to claim 1, wherein the plurality of micromirrors are arranged on the same circle centered on the rotation center axis. 4. In the OCT system, light from the low coherence light source is incident to guide the light from the low coherence light source to the distribution concentrator, and return light from the plurality of optical fibers is incident to the return light. Having a probe optical fiber leading to the interferometer,
The distribution concentrator is provided between the probe optical fiber and the plurality of condensing lenses, sends light from the low coherence light source in parallel to the plurality of condensing lenses, and A fixed lens that collects return light from a plurality of optical fibers and enters the probe optical fiber;
6. The OCT system according to claim 1, wherein the plurality of condensing lenses are arranged on the same circumference with the optical axis of the fixed lens as a center.

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