JP2009172118A - Optical probe and optical tomographic imaging apparatus for OCT - Google Patents

Abstract

In an OCT optical probe that is inserted into a forceps channel of an endoscope and has a function of deflecting light emitted from a peripheral surface of a sheath toward a subject, measurement accuracy due to rotation unevenness of an optical system at a distal end portion The reduction of the deterioration is realized at low cost.
[Solution]
The substantially cylindrical sheath 11 to be inserted into the subject is inserted into the forceps channel 64 in which the electromagnet 65 is disposed on the outer periphery of the insertion portion 55 of the endoscope 50. An optical fiber 12 disposed in the longitudinal direction in the inner space of the sheath 11, a flexible shaft 13 that covers the optical fiber 12 with the inner space, a permanent magnet 18 disposed on the outer periphery of the optical fiber 12, The OCT optical probe 1 is configured by accommodating a tip optical system 15 that deflects light emitted from the tip of the optical fiber 12 and is rotatable about an axis in the longitudinal direction. The electromagnet 65 and the permanent magnet 18 rotate the tip optical system 15 by excitation of the electromagnet 65.
[Selection] Figure 2

Description

  The present invention relates to an optical probe for OCT (Optical Coherence Tomography) and an optical tomographic imaging apparatus using the same, and more specifically, the circumference of the long axis of an optical probe for OCT inserted into a forceps channel of an endoscope insertion portion. The present invention relates to an optical probe for OCT having a function of optically scanning in a direction, and an optical tomographic imaging apparatus that acquires an optical tomographic image of a measurement object using the optical probe for OCT.

  Conventionally, as one method for acquiring a tomographic image of a measurement target such as a biological tissue, a method for acquiring a tomographic image by OCT measurement has been proposed. This OCT measurement is a kind of optical interferometer. After the low-coherent light emitted from the light source is divided into measurement light and reference light, the reflected light from the measurement object when the measurement light is irradiated onto the measurement object. Alternatively, the backscattered light and the reference light are combined, and a tomographic image is acquired based on the intensity of the interference light between the reflected light and the reference light. Hereinafter, the reflected light and the backward scattered light from the measurement object are collectively referred to as reflected light.

  The OCT measurement is roughly divided into two types: TD (Time Domain) -OCT measurement and FD (Fourier Domain) -OCT measurement.

  In TD-OCT measurement, a reflected light intensity distribution corresponding to a position in the depth direction of a measurement target (hereinafter referred to as a depth position) is obtained by measuring the interference intensity while changing the optical path length of the reference light. It is.

  On the other hand, in the FD-OCT measurement, the interference light intensity is measured for each spectral component of the light without changing the optical path lengths of the reference light and the signal light, and the spectral interference intensity signal obtained here is Fourier transformed by a computer. This is a method of obtaining a reflected light intensity distribution corresponding to a depth position by performing a representative frequency analysis. In recent years, FD-OCT measurement has attracted attention as a technique that enables high-speed measurement by eliminating the need for mechanical scanning depending on TD-OCT measurement.

  As a typical apparatus for performing FD-OCT measurement, there are two types, an SD (Spectral Domain) -OCT apparatus and an SS (Swept Source) -OCT apparatus.

  The SD-OCT apparatus uses broadband low-coherent light, decomposes the interference light into each optical frequency component by a spectroscopic means, and measures the interference light intensity for each optical frequency component with an array-type photodetector or the like. The spectral interference obtained in (1) is obtained by constructing a tomographic image by subjecting the waveform to Fourier transform analysis by a computer.

  On the other hand, the SS-OCT apparatus uses a laser or the like that temporally sweeps the optical frequency as a light source, measures the time waveform of the signal corresponding to the temporal change of the optical frequency of the interference light, and obtains the spectral interference obtained thereby. A tomographic image is constructed by Fourier transforming the intensity signal with a computer.

  Conventionally, it has been studied to apply the optical tomographic imaging apparatus of each of the above methods to in-vivo measurement in combination with an endoscope, and an OCT optical probe that can be inserted into a forceps channel of an endoscope is known. It has been.

  Such an optical probe for OCT scans light emitted from the distal end portion in at least a one-dimensional direction in order to acquire a tomographic image along the distal end portion inserted into the body cavity and a surface to be measured. It consists of an end.

  In Patent Document 1, a sheath to be inserted into a subject, a flexible shaft that is rotatable around an axis extending in the longitudinal direction inside the sheath, and the flexible shaft is covered. It has an optical fiber and a tip optical system that deflects light emitted from the optical fiber at a substantially right angle in the longitudinal direction, and a flexible shaft is rotated via a gear by a motor disposed at the base end, An OCT optical probe that rotates an optical system about an axis is shown.

In Non-Patent Document 2, a MEMS motor is provided in the vicinity of the tip of the OCT optical probe inside the sheath in accordance with the recent development of MEMS (Micro Electro Mechanical Systems) technology, and the tip optical system is used as the output shaft of the MEMS motor. An optical probe for OCT that fixes and rotates a tip optical system about an axis is shown.
Japanese Patent No. 3104984 Optics Express, Vol. 15, Issue 16, pp. 10390-10396 (2007)

  However, the conventional OCT optical probe disclosed in Patent Document 1 has a long distance between the distal end optical system at the distal end and the drive means at the proximal end, as shown in FIG. Due to uneven rotation of the tip optical system due to friction between the tip optical system and the like, it is difficult to accurately detect the angle of the tip optical system, and the tomographic image may be deteriorated.

  As shown in FIG. 12, the OCT optical probe shown in Non-Patent Document 1 can deflect and scan light in the vicinity of the tip optical system. However, the MEMS motor is expensive and can be downsized. It may be difficult and difficult to pass through the forceps channel of the endoscope. In addition, there is a possibility that the drive wiring to the MEMS motor blocks light and affects image acquisition.

  In view of the above circumstances, an object of the present invention is to provide an optical probe for OCT that can reduce the degradation of measurement accuracy due to uneven rotation of the optical system at the tip at low cost, and an optical tomographic imaging apparatus using the same. Objective.

  The first OCT optical probe of the present invention has an electromagnetic action between a permanent magnet or electromagnet disposed inside the OCT optical probe and an electromagnet or permanent magnet disposed on the outer periphery of the forceps channel. The OCT optical probe has a function of performing optical scanning in the circumferential direction of the long axis. The present invention also provides an optical tomographic imaging apparatus that acquires an optical tomographic image to be measured by OCT measurement using the OCT optical probe.

  That is, the first OCT optical probe of the present invention is a long OCT optical probe inserted into a forceps channel having an electromagnet disposed on the outer periphery of an insertion portion of an endoscope, A substantially cylindrical sheath inserted into the optical fiber, an optical fiber disposed longitudinally in the inner space of the sheath, a flexible shaft covering the optical fiber with the inner space, and an outer periphery of the optical fiber. And a permanent optical system that deflects light emitted from the tip of the optical fiber and is rotatable about a longitudinal axis, and the electromagnet and the permanent magnet are The optical system is configured to rotate.

  The permanent magnet may be disposed on the outer periphery of the optical fiber via a flexible shaft.

  The second OCT optical probe of the present invention is a long optical probe that is inserted into a forceps channel having a permanent magnet disposed on the outer periphery of an insertion portion of an endoscope, and is inserted into a subject. A substantially cylindrical sheath, an optical fiber disposed in the inner space of the sheath in the longitudinal direction, a flexible shaft covering the optical fiber with the inner space, and an electromagnet disposed on the outer periphery of the optical fiber And a tip optical system that deflects light emitted from the tip of the optical fiber and is rotatable about the longitudinal axis, and the electromagnet and permanent magnet rotate the tip optical system by excitation of the electromagnet. It is comprised so that it may make it.

  The electromagnet may be disposed on the outer periphery of the optical fiber via a flexible shaft.

  In the first and second OCT probes, the rotation of the tip optical system may be a swing within a predetermined angle around the longitudinal axis. The predetermined angle can be set within a desired range based on the shape of the measurement target. For example, in the case of a measurement object having a cylindrical shape such as a bronchus, the entire circumference is in the range around the longitudinal axis, and in the case of a flat measurement object such as a stomach wall, 180 degrees with respect to the longitudinal axis. However, the present invention is not limited to this.

  The optical tomographic imaging apparatus according to the present invention is characterized in that the OCT optical probe according to the present invention is used. More specifically, the optical tomographic imaging apparatus according to the present invention includes a light source unit that emits light, a light dividing unit that divides the light emitted from the light source unit into measurement light and reference light, and measurement light. An irradiation optical system for irradiating the measurement target, a multiplexing means for combining the reflected light from the measurement target and the reference light when the measurement target is irradiated with the measurement light, and the combined reflected light and reference light Based on the detected interference light frequency and intensity, the reflection intensity at a plurality of depth positions of the measurement object is detected, and the reflected light at each of these depth positions is detected. An optical tomographic imaging apparatus comprising a tomographic image processing means for acquiring a tomographic image of a measurement object based on intensity, wherein the irradiation optical system includes the OCT optical probe of the present invention. And

  In the OCT optical probe of the present invention, the distal end optical system has an electromagnet or permanent magnet disposed on the outer periphery of the forceps channel of the endoscope, and a permanent magnet or electromagnet disposed on the outer peripheral surface of the optical fiber. The distance between the tip optical system and the drive means for turning the tip optical system is short because the OCT optical probe rotates around the longitudinal axis of the OCT optical probe. Therefore, uneven rotation of the tip optical system due to friction between the sheath and the flexible shaft is reduced. Further, no driving means such as a MEMS motor is provided in the vicinity of the tip, and there is no problem of increasing the outer diameter of the tip portion or increasing the price of the OCT optical probe.

  As a result, the OCT probe according to the present invention can realize low-cost measurement accuracy degradation due to uneven rotation of the tip optical system due to friction between the sheath and the flexible shaft.

  In addition, since the optical tomographic imaging apparatus according to the present invention is applied with the OCT probe according to the present invention as described above, the rotation of the tip optical system due to friction between the sheath and the flexible shaft or the like. Measurement accuracy deterioration due to unevenness can be realized at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, an outline of the optical tomographic imaging apparatus will be described. FIG. 1 is an overall perspective view of an optical tomographic imaging apparatus to which an OCT optical probe 1 of the present invention is applied.

  The present optical tomographic imaging apparatus includes an endoscope 50 including the OCT optical probe 1, a light source device 51 to which the endoscope 50 is connected, a video processor 52, an optical tomography processing device 53, and a video processor 52. And a monitor 54 connected to the.

  As will be described later, the light source device 51 is for irradiating the measurement light L1 to the portion of the measurement target Sb from which the tomographic image P is acquired.

  The endoscope 50 includes an elongated insertion portion 55 having flexibility, an operation portion 56 connected to the proximal end of the insertion portion 55, and a universal cord 57 extending from a side portion of the operation portion 56. And. A light source connector 58 that is detachably connected to the light source device 51 is provided at the end of the universal cord 57. A signal cable 59 extends from the light source connector 58, and a signal connector 60 that is detachably connected to the video processor 52 is provided at an end of the signal cable 59.

  The insertion unit 55 is inserted into a body cavity, for example, and is used for observing the measurement target Sb. The distal end of the insertion portion 55 is formed to be bendable, and the operation portion 56 is provided with an operation knob 61 for bending the distal end of the insertion portion 55. Inside the insertion portion 55, a forceps channel 64, which is a conduit indicated by a broken line in the figure, is provided for inserting a treatment instrument such as the OCT optical probe 1 and forceps along the longitudinal direction thereof. One end of the forceps channel 64 is opened at the distal end of the insertion portion 55 to become a distal end opening portion 64a, and the other end is a forceps insertion port 64b above the operation portion 56. The OCT optical probe 1 is inserted into the forceps insertion port 64b, the forceps channel 64 is inserted, and the distal end is protruded from the distal end opening 64a, so that the measurement is performed on the measurement target Sb integrally with the endoscope 50. Irradiate light L1. As will be described later, an electromagnet or permanent magnet (not shown) is disposed on the outer periphery of the forceps channel 64. Note that the distal end of the insertion portion 55 is provided with an observation window (not shown) for observing the measurement target Sb, an illumination window for irradiating illumination light, an air supply for removing dirt, a water supply nozzle, and the like.

  The OCT optical probe 1 includes a long, flexible distal end portion 10, a proximal end portion 20 connected to the proximal end of the distal end portion 10, and an optical fiber 12.

  As described above, the distal end portion 10 is inserted into the body cavity through the forceps channel 64 indicated by a broken line in the figure, and has a length of about 3 m.

  One end of the optical fiber 12 is detachably connected to the optical tomography apparatus by an optical tomographic connector 62, and the other end is inserted through the proximal end portion 20 and the distal end portion 10 and extends to the vicinity of the distal end of the distal end portion 10. .

  Next, the OCT optical probe 1 of the present invention will be described in detail.

  FIG. 2 is a diagram showing a first embodiment of the distal end portion 10 of the OCT optical probe 1. 2A is a schematic diagram of the tip portion 10, FIG. 2B is a diagram showing a cross section of the tip portion 10 as viewed from the direction of arrow A shown in FIG. 2A, and FIG. FIG. 3 is a perspective view of a tip portion 10.

  The distal end portion 10 of the OCT optical probe 1 includes a sheath 11, an optical fiber 12, a distal optical system 15, and the like. The sheath 11 is made of a cylindrical member having flexibility. In the present embodiment, the distal end of the sheath 11 has a structure closed by a cap 17.

  The optical fiber 12 is accommodated in the sheath 11. A flexible shaft 13 is fixed to the outer peripheral side of the optical fiber 12.

  The flexible shaft 13 is composed of a close-contact coil in which a metal wire is wound in a tightly wound manner.

  The tip optical system 15 has a substantially spherical shape, deflects the measurement light L1 emitted from the optical fiber 12, condenses the measurement light Sb, and deflects the reflected light L3 from the measurement target Sb. At the same time, the light is condensed and made incident on the optical fiber 12. Here, the focal length of the tip optical system 15 is formed, for example, at a position where the distance D is about 3 mm from the optical axis LP of the optical fiber 12 in the radial direction of the sheath 11. The measurement light L1 emitted from the tip optical system 15 is inclined about 7 degrees from the direction perpendicular to the optical axis LP. The tip optical system 15 is fixed in the vicinity of the light emission position of the optical fiber 12 using a fixing member 14.

In the first embodiment of the distal end portion 10 of the OCT optical probe 1 of the present invention, the permanent magnet 18 is disposed on the outer periphery of the flexible shaft 13, and the electromagnet 65 is disposed on the outer periphery of the forceps channel 64 of the insertion portion 55. It is arranged. Here, the permanent magnet 18 can be disposed directly on the outer periphery of the optical fiber 12 without using the flexible shaft 13, and is not shown on the outer periphery of the permanent magnet 18 in order to detect the rotation angle of the optical fiber 12. It is also possible to arrange a magnetic sensor. The control signal MC to the electromagnet 65 and the rotation signal RS of the magnetic sensor are transmitted by a control cable (not shown). Specifically, the rotation signal RS includes a rotation clock signal R _CLK and a rotation angle signal R _pos when the optical fiber 12 rotates once.

  Hereinafter, the operation of the first embodiment of the OCT optical probe 1 of the present invention will be described.

  By exciting the electromagnet 65, the electromagnet 65 and the permanent magnet 18 interact to form a relationship between a stator and a rotor of a so-called brushless motor, and the optical fiber 12 and the flexible shaft 13 are interposed via the permanent magnet 18. Rotates in the direction of arrow R around the optical axis LP. As the optical fiber 12 rotates, the tip optical system 15 also rotates in the direction of arrow R around the optical axis LP. Accordingly, the OCT optical probe 1 irradiates the measurement target Sb with the measurement light L1 emitted from the distal optical system 15 in the direction of the arrow R around the optical axis LP while scanning in the outer circumferential direction of the sheath 11.

  Further, by controlling the excitation order of the electromagnet 65 by the control signal MC based on the rotation signal RS, the rotation direction of the optical fiber 12 is reversed, and the tip optical system 15 is rotated around the optical axis LP within a predetermined angle range. It can also be swung.

  FIG. 3 is a diagram showing a second embodiment of the distal end portion 10 of the OCT optical probe 1. 3A is a schematic diagram of the tip portion 10, FIG. 3B is a diagram showing a cross section of the tip portion 10 viewed from the direction of arrow A shown in FIG. 3A, and FIG. FIG. 3 is a perspective view of a tip portion 10. In FIG. 3, parts having the same configuration as in the first embodiment are denoted by the same reference numerals and description thereof is omitted. Specifically, a different configuration of the second embodiment will be described.

  In the second embodiment of the distal end portion 10 of the OCT optical probe 1 of the present invention, the electromagnet 19 is disposed on the outer periphery of the flexible shaft 13, and the permanent magnet 66 is disposed on the outer periphery of the forceps channel 64 of the insertion portion 55. It is arranged. Similarly to the first embodiment, the electromagnet 19 can be directly disposed on the outer periphery of the optical fiber 12 without the flexible shaft 13 interposed therebetween. Here, the distal end portion 10 is subjected to an insulation treatment so as not to cause an electric shock or the like on the human body by exciting the electromagnet 19 disposed on the outer periphery of the flexible shaft 13. That is, it differs from 1st Embodiment of the front-end | tip part 10 in the positional relationship of the permanent magnet 66 and the electromagnet 19 being opposite. The operation of the OCT optical probe 1 by exciting the electromagnet 19 is the same as in the first embodiment, and a description thereof will be omitted.

  FIG. 4 is a diagram showing an entire embodiment of the OCT optical probe 1 of the present invention. 4A shows a first embodiment of the OCT optical probe 1 of the present invention, FIG. 4B shows a second embodiment of the OCT optical probe 1 of the present invention, and FIG. 4C shows the present invention. It is a figure which shows 3rd Embodiment of the optical probe 1 for OCT. In FIG. 4, parts having the same configuration are denoted by the same reference numerals and description thereof is omitted. In describing the first to third embodiments, the tip portion 10 will be described based on the first embodiment described above, but the present invention is not limited to this.

  In the first embodiment, the sheath 11 is fitted and fixed to the housing 25, and the bearing 22 is disposed inside the housing 25. The flexible shaft 13 is fixed to a shaft support member 21, and the shaft support member 21 is rotatably held with respect to the housing 25 via a bearing 22. The optical fiber 12 includes a side 12 a that is rotatably held integrally with the flexible shaft 13 and a side 12 b that is fixed at the base end 20, and is optically connected via a rotary joint 23. Has been.

  By exciting the electromagnet 65, the optical fiber 12 a and the flexible shaft 13 rotate around the optical axis LP in the forceps channel 64. As a result, the tip optical system 15 is also integrally rotated in the entire circumferential direction around the optical axis LP (in the direction of arrow R in the figure). Specifically, the rotation frequency is about 10 Hz to 30 Hz, but is not limited to this. When the processing speed of the tomographic image processing means 150 described later is high, it can be further increased. Further, the rotation frequency is not limited to a fixed value, and can be changed according to the operation speed and resolution of the measurement target. Specifically, it is possible to increase the speed for a measurement object that operates fast or a measurement object that does not require high resolution, and to decrease the speed for a measurement object that operates slowly or a measurement object that requires high resolution.

  The second embodiment differs from the first embodiment in that the rotary joint 23 is not provided and the optical fiber 12 is fixed to the housing 25.

  By controlling the excitation order of the electromagnets 65, the optical fiber 12 and the flexible shaft 13 are swung around the optical axis LP in a range of a predetermined angle. As a result, the tip optical system 15 also swings integrally in the circumferential direction around the optical axis LP (in the direction of arrow R in the figure).

  Specifically, the swing angle of the tip optical system 15 can be set to a desired range based on the shape of the measurement target Sb. For example, in the case of the measuring object Sb having a cylindrical shape such as a bronchus, the entire circumference is in the range around the longitudinal axis, and in the case of the measuring object Sb having a flat shape such as the stomach wall, the measuring object Sb is around the longitudinal axis. However, the present invention is not limited to this. In addition, the oscillation frequency is the same as that in the case of rotating in the entire circumferential direction. Further, when the oscillation frequency is equal to the natural frequency of the flexible shaft 13, the flexible shaft 13 is used. Is driven by resonance, and the driving force can be reduced. It is assumed that the swing angle and the swing frequency are within the range of the torsional strength of the optical fiber 12.

  In the third embodiment, a bearing 22 is provided in the middle of the sheath 11 and a shaft fixing member 24 is provided. Thereby, the shaft support member 21 is rotatably held with respect to the sheath 11, and a part of the flexible shaft 13 is fixed to the sheath 11, which is different from the second embodiment.

  Similarly to the second embodiment, the tip optical system 15 is swung in the circumferential direction around the optical axis LP (in the direction of arrow R in the figure) by controlling the excitation order of the electromagnets 65. Only the front end side (left side in the figure) of the shaft fixing member 24 can swing.

  That is, compared with the second embodiment, the swinging portion is shortened, and the driving force can be reduced. Note that the swing angle and the swing frequency are the same as those in the second embodiment, and the description thereof is omitted.

  Next, an optical tomographic imaging apparatus to which the OCT optical probe 1 according to the present invention is applied will be described. FIG. 5 is a diagram showing a schematic configuration of an optical tomographic imaging apparatus 100 to which the OCT optical probe of the present invention is applied.

The optical tomographic imaging apparatus 100 is an optical tomographic imaging apparatus based on SS-OCT measurement. The optical tomographic imaging apparatus 100 is a light source means 110 that emits laser light L, and an optical fiber coupler 2 that divides the laser light L emitted from the light source means 110. And a periodic clock generating means 120 for outputting a periodic clock signal T _CLK from the light divided by the optical fiber coupler 2, and one light divided by the optical fiber coupler 2 is divided into the measuring light L1 and the reference light L2. The light splitting means 3, the optical path length adjusting means 130 for adjusting the optical path length of the reference light L2 split by the light splitting means 3, and the measurement light L1 split by the light splitting means 3 is guided to the measuring object Sb. OCT optical probe 1 to be measured, and reflected light L3 and reference light L2 from the measuring object Sb when the measuring light S1 from the OCT optical probe 1 is irradiated to the measuring object Sb Are combined with each other, an interference light detection means 140 for detecting the interference light L4 between the reflected light L3 and the reference light L2 combined by the multiplexing means 4, and the interference light detection means 140. The apparatus includes a tomographic image processing unit 150 that acquires a tomographic image P of the measurement target Sb by performing frequency analysis on the detected interference light L4, and a display device 160 that displays the tomographic image P.

Light source means 110 of the present device is to emit laser light L while sweeping the wavelength at a constant period T _0. Specifically, the light source means 110 includes a semiconductor optical amplifier (semiconductor gain medium) 111 and an optical fiber FB 10, and has a structure in which the optical five FB 10 is connected to both ends of the semiconductor optical amplifier 111. The semiconductor optical amplifier 111 has a function of emitting weak emission light to one end side of the optical fiber FB10 by injecting drive current and amplifying light incident from the other end side of the optical fiber FB10. When a drive current is supplied to the semiconductor optical amplifier 111, a pulsed laser beam L is emitted to the optical fiber FB0 by the optical resonator formed by the semiconductor optical amplifier 111 and the optical fiber FB10.

  Further, a circulator 112 is coupled to the optical fiber FB10, and a part of the light guided in the optical fiber FB10 is emitted from the circulator 112 to the optical fiber FB11 side. The light emitted from the optical fiber FB11 is reflected by a rotary polygon mirror (polygon mirror) 116 via a collimator lens 113, a diffractive optical element 114, and an optical system 115. The reflected light enters the optical fiber FB11 again via the optical system 115, the diffractive optical element 114, and the collimator lens 113.

  Here, the rotating polygonal mirror 116 rotates in the direction of the arrow R1 at a high speed of, for example, about 30,000 rpm, and the angle of each reflecting surface changes with respect to the optical axis of the optical system 115. Thereby, only the light having a specific wavelength region out of the light dispersed by the diffractive optical element 114 returns to the optical fiber FB11 again. The wavelength of the light returning to the optical fiber FB11 is determined by the angle between the optical axis of the optical system 115 and the reflecting surface. Then, light having a specific wavelength range incident on the optical fiber FB11 is incident on the optical fiber FB10 from the circulator 112, and as a result, laser light L having a specific wavelength range is emitted to the optical fiber FB0 side.

Therefore, when the rotary polygon mirror 116 rotates at a constant speed in the direction of the arrow R1, the wavelength λ of the light incident on the optical fiber FB11 again changes with a constant period as time passes. . As shown in FIG. 6, the light source means 110 emits a laser beam L swept from the minimum sweep wavelength λmin to the maximum sweep wavelength λmax at a constant period T ₀ (for example, about 50 μsec).

  The wavelength-swept laser light L is emitted to the optical fiber FB0 side, and the laser light L is further branched by the optical fiber coupler 2 and is incident on the optical fibers FB1 and FB5, respectively. The light emitted to the optical fiber FB5 is guided to the periodic clock generation means 120.

The periodic clock generation means 120 outputs one periodic clock signal _TCLK each time the wavelength of the laser light L emitted from the light source means 110 is swept for one period. The periodic clock generation unit 120 includes optical lenses 121 and 123, an optical filter 122, and a light detection unit 124. Then, the laser light L emitted from the optical fiber FB5 enters the optical filter 122 via the optical lens 121. The laser light L that has passed through the optical filter 122 is detected by the light detection unit 124 via the optical lens 123, and the periodic clock signal T _CLK is output to the tomographic image processing means 150.

  As shown in FIG. 7A, the optical filter 122 has a function of transmitting only the laser beam L having the set wavelength λref and blocking light in other wavelength bands. The optical filter 122 has a plurality of transmission wavelengths. The optical filter 122 has a light transmission period FSR (free spectrum range) in which one transmission wavelength is set in the wavelength band λmin to λmax among the plurality of transmission wavelengths. Therefore, only the laser beam L having the set wavelength λref set in the wavelength band λmin to λmax in which the wavelength of the laser beam L emitted from the light source unit 110 is swept is transmitted, and the laser beam L having the other wavelength band is transmitted. It will be shielded from light.

As shown in FIG. 7B, when the laser light L whose wavelength is periodically swept is emitted from the light source means 110 and the wavelength of the laser light L becomes the set wavelength λref, the periodic clock signal T _CLK is output. Will be. Thus, by generating and outputting the periodic clock signal T _CLK using the laser light L actually emitted from the light source means 110, the laser light L emitted from the light source means 110 has a predetermined wavelength from the start of wavelength sweeping. Even in a case where the time until the light intensity changes for each period, the interference signal IS in the wavelength band of the constant period T ₀ (see FIG. 6) can be acquired from the set wavelength λref. Therefore, the periodic clock signal _TCLK can be output at the timing of acquiring the interference signal IS in the wavelength band assumed in the tomographic image processing means 150, and degradation of resolution can be suppressed.

  The light splitting means 3 is composed of, for example, a 2 × 2 optical fiber coupler, and splits the laser light L guided from the light source means 110 through the optical fiber FB1 into the measurement light L1 and the reference light L2. The light splitting means 3 is optically connected to the two optical fibers FB2 and FB3, respectively, the measuring light L1 is guided by the optical fiber FB2, and the reference light L2 is guided by the optical fiber FB3. The light dividing means 3 in this embodiment also functions as the multiplexing means 4.

  The OCT optical probe 1 is optically connected to the optical fiber FB2, and the measurement light L1 is guided to the OCT optical probe 1. The OCT optical probe 1 irradiates the measuring object Sb from the distal end portion 10 with the measuring light L1, and the reflected light L3 is guided again through the OCT optical probe 1 by the optical fiber FB2.

  The optical path length adjusting means 130 is disposed on the side of the optical fiber FB3 where the reference light L2 is emitted. The optical path length adjusting unit 130 changes the optical path length of the reference light L2 in order to adjust the position where the tomographic image acquisition is started, and reflects the reference light L2 emitted from the optical fiber FB3. A mirror 132; a first optical lens 131a disposed between the reflecting mirror 132 and the optical fiber FB3; and a second optical lens 131b disposed between the first optical lens 131a and the reflecting mirror 132. is doing.

  The first optical lens 131a has a function of converting the reference light L2 emitted from the optical fiber FB3 into parallel light and condensing the reference light L2 reflected by the reflection mirror 132 onto the optical fiber FB3.

  The second optical lens 131b has a function of condensing the reference light L2 converted into parallel light by the first optical lens 131a onto the reflection mirror 132 and making the reference light L2 reflected by the reflection mirror 132 into parallel light. ing.

  Therefore, the reference light L2 emitted from the optical fiber FB3 is converted into parallel light by the first optical lens 131a, and is condensed on the reflection mirror 132 by the second optical lens 131b. Thereafter, the reference light L2 reflected by the reflecting mirror 132 becomes parallel light by the second optical lens 131b, and is condensed on the optical fiber FB3 by the first optical lens 131a.

  Further, the optical path length adjusting means 130 has a base 133 to which the second optical lens 131b and the reflecting mirror 132 are fixed, and a mirror moving means 134 for moving the base 133 in the optical axis direction of the first optical lens 131a. is doing. Then, when the base 133 moves in the direction of arrow A, the optical path length of the reference light L2 is changed.

  As described above, the multiplexing unit 4 is composed of a 2 × 2 optical fiber coupler, and combines the reference light L2 whose optical path length is adjusted by the optical path length adjusting unit 130 and the reflected light L3 from the measurement target Sb. In addition, the light is emitted to the interference light detection means 140 through the optical fiber FB4.

  The interference light detection unit 140 detects the interference light L4 between the reflected light L3 and the reference light L2 combined by the multiplexing unit 4, and outputs an interference signal IS. In this apparatus, the interference light L4 is divided into two by the light splitting means 3, guided to the photodetectors 140a and 140b, and calculated to have a mechanism for performing balance detection. The interference signal IS is output to the tomographic image processing means 150.

  FIG. 8 is a diagram showing a schematic configuration of the tomographic image means 150. The tomographic image means 150 is realized by executing a tomographic image program read into the auxiliary storage device on a computer (for example, a personal computer). The tomographic image processing unit 150 includes an interference signal acquisition unit 151, an interference signal conversion unit 152, an interference signal analysis unit 153, a tomographic information generation unit 154, an image correction unit 155, and a rotation control unit 156.

The interference signal acquisition unit 151 acquires the interference signal IS for one cycle detected by the interference light detection unit 140 based on the periodic clock signal _TCLK output from the periodic clock generation unit 120. The interference signal acquisition unit 151 acquires the interference signal IS in the wavelength band DT (see FIG. 7B) before and after the output timing of the periodic clock signal _TCLK . Note that the interference signal acquiring unit 151, as long as it acquires the interference signal IS for one period of the output timing of the periodic clock signal T _CLK as a reference, the output timing of the periodic clock signal T _CLK is swept wavelength If it is within the band, it may be set immediately after the start of the wavelength sweep or immediately before the end of the wavelength sweep.

  The interference signal conversion means 152 rearranges the interference signals IS acquired by the interference signal acquisition means 151 so as to be equidistant on the wavenumber k (= 2π / λ) axis. FIG. 9A is a diagram illustrating the interference signal IS input to the interference signal acquisition unit 151. FIG. 9B shows the rearranged interference signal IS. Specifically, the interference signal converting means 152 has a time-wavelength sweep characteristic data table or function of the light source means 110 in advance, and the time-wavelength sweep characteristic data table or the like is used at equal intervals on the wavenumber k axis. The interference signal IS is rearranged so that Thus, when calculating tomographic information from the interference signal IS, highly accurate tomographic information is obtained by a spectrum analysis method that assumes that the frequency space is equal in frequency space such as Fourier transform processing and processing by the maximum entropy method. be able to. The details of this signal conversion method are disclosed in US Pat. No. 5,956,355.

  The interference signal analysis unit 153 converts the interference signal IS converted by the interference signal conversion unit 152 into the tomographic information r (z) by a known spectrum analysis technique such as Fourier transform processing, maximum entropy method, Yule-Walker method, and the like. To get.

The rotation control means 156 outputs a control signal MC to the electromagnets 19 and 65 and receives a rotation signal RS from the magnetic sensor. As described above, the rotation position signal RS includes the rotation clock signal R _CLK and the rotation angle signal R _pos when the optical fiber 12 rotates once.

  The tomographic information generating means 154 scans the tomographic information r (z) for one period (one line) acquired by the interference signal analyzing means 153 in the radial direction of the distal end portion 10 of the OCT optical probe 1 (R1 in the figure). Direction), and a tomographic image P as shown in FIG. 10 is generated. The tomographic information generating unit 154 stores the tomographic information r (z) for one line acquired sequentially in the tomographic information accumulating unit 154a.

Here, the tomographic information generating unit 154 can read the tomographic information r (z) from the tomographic information accumulating unit 154a in a batch based on the rotation clock signal R _CLK input to the rotation control unit 156 and generate the tomographic image P. .

The tomographic information generation means 154 can also read the tomographic information r (z) sequentially from the tomographic information storage means 154a and generate the tomographic image P based on the rotation angle signal R _pos input to the rotation control means 156. .

  The image quality correction unit 155 performs a sharpening process, a smoothing process, and the like on the tomographic image P generated by the tomographic information generation unit 154.

  The display unit 160 displays the tomographic image P that has been subjected to sharpening processing, smoothing processing, and the like by the image quality correction unit 155.

  Therefore, in the OCT optical probe 1 and the optical tomographic imaging apparatus 100 using the OCT optical probe 1 of the present invention, the distal optical system 15 of the distal end portion 10 is arranged on the outer periphery of the forceps channel 64 of the endoscope 50. The electromagnet 65 or the permanent magnet 66 provided and the permanent magnet 18 or the electromagnet 19 disposed on the outer peripheral surface of the optical fiber 12 are rotated around the longitudinal axis of the OCT optical probe 1 by an electromagnetic action. Since the distance between the distal optical system 15 and the driving means for rotating the distal optical system 15 is short, the distal optical system 15 due to friction between the sheath 11 and the flexible shaft 13 or the like. Rotation unevenness is reduced. Further, no driving means such as a MEMS motor is provided in the vicinity of the tip, and there is no problem of increasing the outer diameter of the tip portion 10 or increasing the price of the OCT optical probe 1.

  As a result, the OCT optical probe 1 of the present invention can realize low-cost measurement accuracy degradation due to uneven rotation of the tip optical system 15 due to friction between the sheath 11 and the flexible shaft 13 or the like.

  In addition, since the optical tomographic imaging apparatus 100 according to the present invention is applied with the OCT probe 1 according to the present invention as described above, the tip due to friction between the sheath 11 and the flexible shaft 13 or the like. Measurement accuracy deterioration due to rotation unevenness of the optical system 15 can be realized at low cost.

  In the above description, the SS-OCT apparatus has been described as an example of the optical tomographic imaging apparatus to which the OCT optical probe 10 of the present invention is applied. However, the optical tomography apparatus is applied to an SD-OCT apparatus and a TD-OCT apparatus. It is also possible to do.

1 is an overall perspective view of an optical tomographic imaging apparatus to which an OCT optical probe 1 of the present invention is applied. The figure which shows 1st Embodiment of the front-end | tip part 10 of the optical probe 1 for OCT of this invention. The figure which shows 2nd Embodiment of the front-end | tip part 10 of the optical probe 1 for OCT of this invention. The figure which shows 1st Embodiment of the optical probe 1 for OCT of this invention. The figure which shows 2nd Embodiment of the optical probe 1 for OCT of this invention. The figure which shows 3rd Embodiment of the optical probe 1 for OCT of this invention. The figure which shows schematic structure of the optical tomographic imaging apparatus to which the optical probe 1 for OCT of this invention is applied. The figure which shows the sweep of the wavelength of the light inject | emitted from the light source means 110 The figure which shows the periodic clock signal produced | generated by the periodic clock generation means 120 The figure which shows the structure of the tomographic image means 150. The figure which shows the interference signal IS input into the interference signal acquisition means 151 Diagram showing the rearranged interference signal IS The figure which shows the tomographic image produced | generated by the tomographic information production | generation means 154 Schematic diagram showing a conventional OCT optical probe Schematic showing an optical probe for OCT using a MEMS motor

Explanation of symbols

L laser light L1 measurement light L2 reference light L3 reflected light L4 interference light P tomographic image Sb measurement object 1 OCT optical probe 3 light splitting means 4 multiplexing means 11 sheath 12 optical fiber 13 flexible shaft 15 tip optical system 18 permanent Magnet 19 Electromagnet 50 Endoscope 55 Insertion section 64 Forceps channel 65 Electromagnet 66 Permanent magnet 100 Optical tomographic imaging apparatus 110 Light source means 140 Interference light detection means 150 Tomographic image processing means

Claims (6)

An elongated OCT optical probe that is inserted into a forceps channel having an electromagnet disposed on the outer periphery of an insertion portion of an endoscope,
A substantially cylindrical sheath inserted into the subject;
An optical fiber disposed in the longitudinal direction in the internal space of the sheath;
A flexible shaft covering the optical fiber with the internal space;
A permanent magnet disposed on the outer periphery of the optical fiber;
A tip optical system that deflects light emitted from the tip of the optical fiber and is rotatable about the longitudinal axis;
An optical probe for OCT, wherein the electromagnet and the permanent magnet are configured to rotate the tip optical system by excitation of the electromagnet.   The optical probe for OCT according to claim 1, wherein the permanent magnet is disposed through the flexible shaft. An elongated OCT optical probe inserted through a forceps channel having a permanent magnet disposed on the outer periphery of an insertion portion of an endoscope,
A substantially cylindrical sheath inserted into the subject;
An optical fiber disposed in the longitudinal direction in the internal space of the sheath;
A flexible shaft covering the optical fiber with the internal space;
An electromagnet disposed on the outer periphery of the optical fiber;
A tip optical system that deflects light emitted from the tip of the optical fiber and is rotatable about the longitudinal axis;
An optical probe for OCT, wherein the electromagnet and the permanent magnet are configured to rotate the tip optical system by excitation of the electromagnet.   The optical probe for OCT according to claim 3, wherein the electromagnet is disposed via the flexible shaft.   5. The OCT optical probe according to claim 1, wherein the tip optical system is pivoted within a range of a predetermined angle around the longitudinal axis. 6. Light source means for emitting light;
A light splitting means for splitting light emitted from the light source into measurement light and reference light;
An irradiation optical system for irradiating the measurement object with the measurement light;
A multiplexing means for multiplexing the reflected light from the measurement object and the reference light when the measurement object is irradiated with the measurement light;
Interference light detection means for detecting interference light between the reflected light and the reference light combined;
Based on the frequency and intensity of the detected interference light, the reflection intensity at a plurality of depth positions of the measurement object is detected, and the tomographic image of the measurement object is obtained based on the intensity of the reflected light at each depth position. In an optical tomographic imaging apparatus comprising a tomographic image processing means for acquiring,
An optical tomographic imaging apparatus, wherein the irradiation optical system is configured to include the OCT optical probe according to any one of claims 1 to 5.

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