JP2007268058A - Optical probe and optical tomographic imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a local pressure change, a stress change caused by bending, and a decrease in the accuracy of measurement caused by a fluctuation in temperature. <P>SOLUTION: An optical fiber 13 is arranged in the internal space of an outer tube 11 of a tubular probe in the state of being elongated in the longitudinal direction of the outer tube 11. Light, which is emitted from a leading end of an optical fiber 13, is collected by a light collecting means 18, and converged on a body-to-be-scanned which is arranged on the outside of the outer tube 11 of the probe. A sealing member makes the optical fiber 13 sealed in air pressure higher than atmospheric pressure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical probe and an optical tomographic imaging apparatus that have a cylindrical probe outer cylinder and have a function of emitting light from its peripheral surface.

  Conventionally, as one method for acquiring a tomographic image of a measurement target such as a living tissue, for example, as shown in Patent Documents 1 and 2, a method for acquiring an optical tomographic image by OCT (Optical Coherence Tomography) measurement has been proposed. ing. This OCT measurement is a kind of optical interference measurement, and optical interference is detected only when the optical path length of the light divided into two, that is, the measurement light and the reference light is within a range within the coherence length of the light source. This is a measurement method using this. That is, in this method, the low coherent light emitted from the light source is divided into measurement light and reference light, the measurement light is irradiated onto the measurement object, and the reflected light from the measurement object is guided to the multiplexing means. On the other hand, the optical path length of the reference light is adjusted so that the optical path length is the same as the reflected light from an arbitrary place to be measured in the measurement target, and the reference light is guided to the multiplexing means. Then, the measuring light and the reference light are combined by the combining means, and the light intensity is detected by the photodetector.

  In order to obtain a one-dimensional tomographic image, the optical path length of the measurement light is scanned according to the measurement area, and an interference intensity waveform corresponding to the reflectance distribution along the same axis as the measurement light traveling direction is obtained. It is done. That is, a light reflection intensity distribution according to the structure in the depth direction of the measurement target can be obtained. Furthermore, a tomographic image of a two-dimensional light reflection intensity is obtained by scanning the irradiation position of the measurement light applied to the measurement object in a one-dimensional direction perpendicular to the optical axis using a deflection means or a physical movement means. It is done. Furthermore, a tomographic image having a three-dimensional light reflection intensity can be obtained by scanning the irradiation position of the measurement light over a two-dimensional direction perpendicular to the optical axis direction.

  In the OCT apparatus, by changing the optical path length of the reference light, the measurement position (measurement depth) with respect to the measurement object is changed and a tomographic image is acquired. This method is generally called TD-OCT (Time domain OCT) measurement. More specifically, the optical path length adjustment mechanism of the reference light in Patent Document 1 has an optical system that focuses the reference light emitted from the optical fiber onto the mirror, and moves only the mirror in the beam axis direction of the reference light. The optical path length is adjusted. The optical path length adjustment mechanism for the reference light shown in Patent Document 2 collimates the reference light emitted from the optical fiber by the lens, and condenses the reference light that has become parallel light again by the optical path length adjustment lens. The light is incident on the fiber, and the optical path length is adjusted by advancing and retracting the optical path length adjusting lens in the beam axis direction of the reference light.

  On the other hand, an optical tomographic imaging apparatus based on SD-OCT (Spectral Domain OCT) measurement has been proposed as an apparatus for acquiring a tomographic image at high speed without changing the optical path length of the reference light described above. In the SD-OCT apparatus, as in the above TD-OCT, a broadband low-coherent light divided into a measurement light and a reference light using an interferometer is caused to interfere with the optical path length being almost equal, and then the interference light is spectrally separated. By measuring the interference light intensity for each optical frequency component with an array type photodetector, and analyzing the resulting spectrum interference waveform with a Fourier transform using a computer. Thus, a one-dimensional tomographic image in the optical axis direction is constructed without physically performing the above scanning. Similar to the TD-OCT, a two-dimensional or three-dimensional tomographic image can be obtained by scanning the irradiation position of the measurement light in a direction perpendicular to the optical axis.

  Furthermore, an optical tomographic imaging apparatus based on SS-OCT (Swept source OCT) measurement has been proposed as an apparatus for acquiring a tomographic image at high speed without changing the optical path length of the reference light (see, for example, Non-Patent Document 1). ). This SS-OCT apparatus uses an optical frequency variable laser light source as a light source. The high coherence laser light is divided into measurement light and reference light, the measurement light is irradiated onto the measurement object, and the reflected light from the measurement object is guided to the multiplexing means. On the other hand, the reference light is guided to the multiplexing means after interfering with the measurement light and the optical path length approximately equal to each other. Then, the measuring light and the reference light are combined by the combining means, and the light intensity is detected by the photodetector. By scanning the frequency of the optical frequency variable laser light source, the interference light intensity for each optical frequency component is measured, and the spectral interference waveform obtained here is Fourier transformed by a computer to physically scan the optical path length. In this way, a one-dimensional tomographic image in the optical axis direction is constructed. Similar to the TD-OCT, a two-dimensional or three-dimensional tomographic image can be obtained by scanning the irradiation position of the measurement light in a direction perpendicular to the optical axis.

By the way, 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. Usually, a tomographic image along a certain surface of the measurement target is acquired, and for this purpose, it is necessary to scan the measurement light in the measurement target at least in a one-dimensional direction perpendicular to the optical axis. As one of means for performing such optical scanning, conventionally, as shown in Patent Document 3, a cylindrical probe outer cylinder is provided, and light emitted from the peripheral surface of the outer cylinder is along the peripheral surface. An optical probe having a function of deflecting in a different direction is known. More specifically, the optical probe includes an insertion portion (probe outer cylinder) to be inserted into the subject, a rotatable hollow shaft inserted into the inner space of the probe outer cylinder, and the shaft. And an optical deflection element that is fixed to the tip of the shaft and rotates together with the shaft and deflects light emitted from the tip of the optical fiber in a direction around the peripheral surface of the probe outer cylinder.
JP-A-6-165784 JP 2003-139688 A Japanese Patent No. 3104984 Optics Express Vol. 12, p. 2977 (2004)

  When inserting a probe as shown in Patent Document 3 into a living body, local pressure changes, stress changes due to fiber bending, and temperature fluctuations are inevitable. In a fiber interferometer that performs interference measurement using a fiber as well as the above-described OCT, if an external pressure, strain, or temperature change is applied to one of the fibers, the refractive index or physical length changes, resulting in about 10 times the wavelength. It has been known for a long time that a phenomenon occurs in which the optical path length changes. Here, in the TD-OCT method, the optical path length on the reference light side is scanned at a high speed, and the interference of the interference signal is obtained to obtain the interference signal. The impact is not significant because it is small enough. However, in the SS-OCT method and the SD-OCT method, since the optical interference waveform is measured in the frequency region while the optical path length of the reference light is fixed, if the optical path length varies during the measurement, the information is distorted or erased. Will happen.

  Specifically, in the SS-OCT method, while scanning the light source wavelength, the phase of the light fluctuates due to the fluctuation of one of the optical path lengths, and the position deviated from the original reflection point position after Fourier transform. Is observed, and the resolution is degraded. Further, in the SD-OCT method, signals in the frequency domain are acquired in a lump. However, if the optical path length fluctuates in a time shorter than the shutter time, signal averaging occurs, and the signal-to-noise ratio of the signal is reduced. There's a problem.

  The present invention has been made in view of the above circumstances, and an optical probe capable of reducing local pressure changes, stress changes due to bending, and deterioration in measurement accuracy due to temperature fluctuations, and optical tomographic imaging using the same An object is to provide an apparatus.

  The optical probe of the present invention condenses light emitted from the tip of an optical fiber, a cylindrical probe outer cylinder, an optical fiber disposed in the inner space of the probe outer cylinder in the axial direction of the probe outer cylinder, and And a condensing means for converging on the scanning object arranged outside the probe outer cylinder, and a sealing member for sealing the optical fiber in a pressure higher than atmospheric pressure. .

  Here, as long as the sealing member seals the optical fiber, the probe outer cylinder itself may function as a sealing member regardless of its structure, or a separate sealing member may be provided in the probe outer cylinder. Anyway. In addition, when a probe outer cylinder functions as a sealing member, the partition member for sealing in any site | part of a probe outer cylinder will be provided.

  Moreover, you may further provide the pressure adjustment means to adjust so that the pressure in a sealing member may become substantially constant. The pressure adjusting means may be any means for adjusting the pressure, for example, it may be made substantially constant using the atmosphere, or the pressure may be adjusted by a mechanical action using a spring, hydraulic pressure, etc. May be made substantially constant. At this time, it may further include a telescopic balloon provided on the outer wall surface of the probe outer cylinder, and the pressure adjusting means may control expansion and contraction of the balloon.

  On the other hand, the optical tomographic imaging apparatus according to the present invention is characterized in that the optical probe according to the present invention is used in the optical tomographic imaging apparatus of each measurement method as described above. More specifically, the optical tomographic imaging apparatus according to the present invention includes a light source that emits light, a light splitting unit that splits the light emitted from the light source into measurement light and reference light, and the measurement light as a measurement target. Irradiating optical system for irradiating with, combining means for combining the reflected light from the measuring object and the reference light when the measuring object is irradiated with the measuring light, and interference between the combined reflected light and the reference light Based on the interference light detecting means for detecting the light and the frequency and intensity of the detected interference light, the intensity of the reflected light at a plurality of depth positions of the measurement target is detected, and the reflected light at each depth position is detected. In an optical tomographic imaging apparatus comprising an image acquisition means for acquiring a tomographic image of a measurement object based on the intensity of the light, the irradiation optical system includes the optical probe according to the present invention. Is.

  According to the optical probe of the present invention and the optical tomographic imaging apparatus using the same, a cylindrical probe outer cylinder, an optical fiber disposed in the axial direction of the probe outer cylinder in the inner space of the probe outer cylinder, Condensing means for condensing the light emitted from the tip of the fiber and converging it on the scanned object arranged outside the probe outer cylinder, and a sealing member for sealing the optical fiber in a pressure higher than atmospheric pressure When the optical probe is inserted into the living body, or when a local pressure change, stress change due to bending, and temperature change are applied to the optical probe, the light in the probe outer tube is added. The influence on the fiber can be mitigated by the pressure in the sealing member, and the degradation of measurement accuracy can be prevented.

  In addition, when pressure adjusting means for adjusting the pressure in the sealing member to be substantially constant is provided, even if a local pressure change or stress change occurs in the probe outer tube, The applied pressure can be made constant, and the influence of the pressure change can be minimized.

  Further, when the probe further has an expandable / contractible balloon provided on the outer wall surface of the probe outer cylinder, and the pressure adjusting means controls the expansion / contraction of the balloon, the expansion / contraction operation of the balloon is performed using the pressure adjustment function in the sealing member. It can be performed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a partially broken side surface shape of an optical probe 10 according to a first embodiment of the present invention. The optical probe 10 constitutes, for example, a distal end portion of an endoscope that is a part of the optical tomographic imaging apparatus, and FIG. 2 shows the overall shape of the optical tomographic imaging apparatus.

  First, an outline of the optical tomographic imaging apparatus will be described with reference to FIG. This apparatus includes an endoscope 50 including the optical probe 10, a light source device 51, a video processor 52 and an optical tomography processing device 53 to which the endoscope 50 is connected, and a monitor 54 connected to the video processor 52. I have. The endoscope 50 includes an elongated probe outer tube 11 having flexibility, an operation unit 56 connected to the rear end of the probe outer tube 11, and a universal extending from a side portion of the operation unit 56. Code 57 is provided.

  A light guide (not shown) that transmits illumination light from the light source device 51 is inserted into the universal cord 57, and a light source connector that is detachably connected to the light source device 51 at the end of the universal cord 57 58 is provided. 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 light source device 51 is for irradiating illumination light to a portion of the subject 70 from which a tomographic image is acquired as described later.

  Further, the operation section 56 is provided with a bending operation knob 61 for bending the bending section provided in the probe outer cylinder 11, and a light guide driving section 62. The light guide driving section 62 and the optical tomography processing apparatus 53 is connected via a ride guide 63. The probe outer cylinder 11 is inserted into a subject 70 such as a human organ.

  Next, the optical probe 10 will be described with reference to FIG. 1 and FIG. The optical probe 10 includes a cylindrical probe outer cylinder 11 with a closed tip, and a single optical fiber 13 disposed in an inner space of the probe outer cylinder 11 so as to extend in the axial direction of the outer cylinder 11. A gear 14a fixed to a part of the outer peripheral surface of the optical fiber 13, a gear 14b meshing with the gear 14a, and a motor 15 for rotating the gear 14b are provided.

  Further, the optical probe 10 has a rod lens (condensing means) 18 fixed to the tip of the optical fiber 13 and a prism mirror 17 fixed to the rod lens 18. The prism mirror 17 changes the optical path of the light L emitted from the tip of the optical fiber 13 by 90 ° and rotates together with the rotation of the optical fiber 13 as described above to probe the light L emitted from the tip of the optical fiber 13. The outer cylinder 11 is deflected in the circumferential direction. Further, the rod lens 18 condenses the light L emitted from the tip of the optical fiber 13 so as to converge on the subject 70 as a scanning body disposed outside the probe outer cylinder 11. In this embodiment, as will be described later, the rod lens 18 and the prism mirror 17 guide light L reflected by the subject 70 to the tip of the optical fiber 13 and enter the optical fiber 13 from the tip. Doubles as

  Here, the internal space 12 in the probe outer cylinder 11 is sealed by the probe outer cylinder 11 and the partition member 16. That is, the probe outer cylinder 11 and the partition member 16 function as a sealing member. The pressure in the sealed internal space 12 is higher than atmospheric pressure.

  As shown in FIG. 2, the incident optical system 20 is disposed inside the endoscope 50 so as to face the proximal end of the optical fiber 13. Light L guided through the ride guide 63 and emitted therefrom is collected by the incident optical system 20 and enters the optical fiber 13 from the base end.

  Hereinafter, the operation of the optical probe 10 having the above configuration will be described. A light source (not shown) such as a laser is disposed in the optical tomography processing device 53 shown in FIG. 2, and light L such as laser light emitted from the light tomography enters the ride guide 63 and is guided there. The light L that has passed through the incident optical system 20 from the ride guide 63 is guided through the optical fiber 13 and emitted from the tip thereof. After being condensed by the rod lens 18, it is reflected by the prism mirror 17 to change the optical path by 90 °. The light is emitted from the translucent probe outer cylinder 11 to the outside of the probe. When the motor 15 is driven, the optical fiber 13 is rotated as described above, and the prism mirror 17 and the rod lens 18 fixed thereto are also rotated.

  When the prism mirror 17 rotates as described above, the light L emitted therefrom is deflected in the circumferential direction of the probe outer cylinder 11 and scans the subject 70 in the direction of arrow R in FIG. The light L is reflected while being scattered by the subject 70, and a part of the reflected light enters the prism mirror 17 and is reflected toward the rod lens 18 side. The reflected light is collected by the rod lens 18 and enters the optical fiber 13 from the tip of the optical fiber 13.

  The reflected light propagated in the optical fiber 13 is emitted from the base end of the optical fiber 13 and enters the ride guide 63 through the incident optical system 20 shown in FIG. The light is transmitted to the processing device 53. In the optical tomography processing device 53, the reflected light is branched from the optical path of the light L toward the optical probe 10 and is detected by a photodetector (not shown). Then, a tomographic image of the subject 70 is formed based on the output of the photodetector, and the tomographic image is displayed on the monitor 54.

  Here, by making the pressure of the internal space 12 of the probe outer cylinder 11 higher than the atmospheric pressure, a local pressure change is applied to the optical probe 10 during or when the optical probe 10 is inserted into the living body. Alternatively, even when a stress change due to bending occurs, since the inside of the probe outer cylinder 11 is at a high pressure, the influence of the pressure change / stress change on the optical fiber 13 can be suppressed, and the pressure change / stress change can be suppressed. It is possible to reduce a decrease in resolution caused by a change in the optical path length.

  Furthermore, even when temperature fluctuations, especially local and rapid temperature changes, occur due to the insertion of the optical probe 10 into the living body, local thermal changes are dispersed by the heat insulation effect of the gas, and the response You can delay the time. As a result, the influence on the data distortion of the OCT system can be reduced.

  Hereinafter, a second embodiment to a fourth embodiment of the present invention will be described with reference to FIGS. In the optical probes 100, 120, and 140 in FIGS. 3 to 5, the same elements as those in FIG. 1 or FIG. 2 are denoted by the same reference numerals, and description thereof is omitted unless particularly required.

  First, a second embodiment of the present invention will be described with reference to FIG. In the optical probe 100 of FIG. 3A, the optical fiber 13 is sealed by a sealing member 112, and the pressure in the sealing member 112 is higher than atmospheric pressure. The sealing member 112 rotates with the optical fiber 12. Thereby, as described above, it is possible to prevent the measurement accuracy from deteriorating and to reliably prevent the air in the internal space 12 from leaking from the probe outer cylinder 11. In addition, although the case where the sealing member 112 covers only the optical fiber 12 is illustrated, the sealing member 112 may cover other than the light emitting portion of the prism mirror 17 or may have a high transmittance with respect to the wavelength of the light L. The prism mirror 17 and the rod lens 18 may be entirely covered as long as they are made of a material having

  Furthermore, a fiber holding member 121 may be provided between the probe outer tube 11 and the optical fiber 13 as shown in FIG. The fiber holding member 121 is formed extending from the inner wall surface of the probe outer cylinder 11 toward the center. For example, the optical fiber 13 is fixed near the approximate center of the probe outer cylinder 11. As a result, local pressure due to the optical fiber 13 sticking to the inner wall surface of the probe outer cylinder 11 can be reliably prevented from being transmitted to the optical fiber 13, and deterioration in measurement accuracy can be prevented. Note that a soft material may be used for the fiber holding member 121 so that the fiber holding member 121 also functions as a buffer material.

  Further, as shown in FIG. 3C, a buffer member 141 made of a soft material such as a cylindrical shaft, a spring, rubber, or sponge may be provided between the probe outer cylinder 11 and the sealing member 112. As a result, the influence on the optical fiber 13 due to the local pressure change / stress change to the optical probe 10 can be surely suppressed, and the decrease in resolution due to the optical path length change caused by the pressure change / stress change is reduced. can do. The fiber holding part 121 and the buffer member 141 can also be provided in the optical probe 10 of FIG.

  Next, a third embodiment of the present invention will be described with reference to FIG. The optical probe 120 in FIG. 4A is provided with a pressure adjusting means 141 that adjusts the pressure in the inner space 12 of the probe outer cylinder 11 to be substantially constant. The pressure adjusting means 141 is composed of, for example, a spring connected to the partition member 16, and when the pressure is applied from the outside of the probe outer cylinder 11, the spring contracts to reliably disperse the locally applied pressure / stress and It is possible to suppress a change in the optical path length of the fiber 13 and suppress deterioration in measurement accuracy. In addition, although the case where the pressure adjusting means 141 is a spring is illustrated, any mechanism that generally performs pressure adjustment such as hydraulic pressure or atmospheric pressure may be used. In FIG. 4A, a partition member 116 is also provided on the rod lens 18 side of the optical fiber 13 so that the pressure in the space between the partition members 16 and 116 is adjusted. The present invention can also be applied to the case where only the partition member 16 is provided as shown in FIG.

  Further, as shown in FIG. 4B, the pressure adjusting means 141 may adjust the pressure by discharging or sucking gas (air) into the internal space 12, for example. At this time, the pressure adjusting means 141 adjusts the pressure in the internal space 12 to be higher than the atmospheric pressure, and adjusts the pressure in the internal space 12 to be substantially constant. In this way, by adjusting the pressure using the gas, the pressure can be kept constant even when a hole is opened in the probe outer cylinder 11, and an external liquid flows from the hole. Can be prevented.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. The optical probe 140 of FIG. 5A is an application of the optical probe 120 of FIG. 4B, and a balloon 162 made of elastic rubber or the like is fixed to the outer wall surface of the probe outer cylinder 11, and the probe The outer cylinder 11 has a through-hole 161 for flowing air into the balloon 162 and applying pressure by the operation of the pressure adjusting means 141. When the gas is sent from the pressure adjusting means 141 into the probe outer cylinder 11, the gas flows into the balloon 162 from the through hole 161, and the balloon 162 is expanded as shown in FIG. ing. As a result, the optical probe 140 and its tip position can be fixed in the body cavity, and the pressure adjustment function and the balloon expansion / contraction function can be combined. Note that the gas pressure to be output is changed between a mode in which the pressure in the probe outer cylinder 11 is kept constant and a mode in which the balloon 162 is inflated.

  Hereinafter, an example of an optical tomographic imaging apparatus to which the optical probe according to the present invention is applied will be described. First, an optical tomographic imaging apparatus 1 shown in FIG. 6 acquires a tomographic image of a measurement target such as a living tissue or a cell in a body cavity by the above-described SD-OCT measurement, and is a light source unit that emits light La. 210, light splitting means 3 for splitting the light La emitted from the light source unit 210 into measurement light L1 and reference light L2, and optical path length adjustment for adjusting the optical path length of the reference light L2 split by the light splitting means 3 Means 220, an optical probe 10 for irradiating the measuring object Sb with the measuring light L1 split by the light splitting means 3, and thus the reflected light L3 reflected by the measuring object Sb when the measuring object Sb is irradiated with the measuring light L1. And a reference light L2 are combined, and an interference light detection means 240 that detects the interference light L4 between the combined reflected light L3 and the reference light L2.

  The light source unit 210 emits low-coherent light La, for example, a light source 111 such as SLD (Super Luminescent Diode), ASE (Amplified Spontaneous Emission), or supercontinuum that obtains broadband light by irradiating a nonlinear medium with ultrashort pulse laser light. And an optical system 112 for causing the light emitted from the light source 111 to enter the optical fiber FB1.

  The light splitting means 3 is composed of, for example, a 2 × 2 optical fiber coupler, and splits the light La guided from the light source unit 210 through the optical fiber FB1 into the measurement light L1 and the reference light L2. This light splitting means 3 is optically connected to two optical fibers FB2 and FB3, respectively, and the measuring light L1 is guided through the optical fiber FB2, and the reference light L2 is guided through the optical fiber FB3. The light splitting means 3 in this example also functions as the multiplexing means 4.

  1 is optically connected to the optical fiber FB2, and the measurement light L1 is guided from the optical fiber FB2 to the optical probe 10. The optical probe 10 is inserted into a body cavity from a forceps port through a forceps channel, for example, and is detachably attached to the optical fiber FB2 by an optical connector 31.

  On the other hand, an optical path length adjusting means 220 is disposed on the side of the optical fiber FB3 from which the reference light L2 is emitted. The optical path length adjusting unit 220 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. 22, a first optical lens 21 a disposed between the reflection mirror 22 and the optical fiber FB 3, and a second optical lens 21 b disposed between the first optical lens 21 a and the reflection mirror 22. Yes.

  The first optical lens 21a has a function of converting the reference light L2 emitted from the core of the optical fiber FB3 into parallel light and condensing the reference light L2 reflected by the reflection mirror 22 onto the core of the optical fiber FB3. ing. Further, the second optical lens 21b condenses the reference light L2 converted into parallel light by the first optical lens 21a on the reflection mirror 22, and makes the reference light L2 reflected by the reflection mirror 22 into parallel light. have. That is, a confocal optical system is formed by the first optical lens 21a and the second optical lens 21b.

  Accordingly, the reference light L2 emitted from the optical fiber FB3 is converted into parallel light by the first optical lens 21a, and is condensed on the reflection mirror 22 by the second optical lens 21b. Thereafter, the reference light L2 reflected by the reflecting mirror 22 becomes parallel light by the second optical lens 21b, and is condensed on the core of the optical fiber FB3 by the first optical lens 21a.

  Further, the optical path length adjusting means 220 includes a base 23 on which the second optical lens 21b and the reflecting mirror 22 are fixed, and a mirror moving means 24 for moving the base 23 in the optical axis direction of the first optical lens 21a. is doing. When the base 23 moves in the direction of arrow A, the optical path length of the reference light L2 can be changed.

  Further, the multiplexing means 4 is composed of a 2 × 2 optical fiber coupler as described above, the reference light L2 that has been subjected to frequency shift and optical path length change by the optical path length adjusting means 220, and the reflected light L3 from the measurement object Sb. Are combined and emitted to the interference light detection means 240 side via the optical fiber FB4.

  On the other hand, the interference light detecting means 240 detects the interference light L4 between the reflected light L3 combined by the multiplexing means 4 and the reference light L2, and uses the interference light L4 emitted from the optical fiber FB4 as parallel light. The collimator lens 141 to be converted, the spectroscopic means 142 for dispersing the interference light L4 having a plurality of wavelength bands for each wavelength band, and the light detection means 144 for detecting the interference light L4 of each wavelength band split by the spectroscopic means 142. And have.

  The spectroscopic means 144 is composed of, for example, a diffraction grating element or the like. The spectroscopic light L4 incident on the spectroscopic means 144 is split and emitted toward the light detecting means 144. Further, the light detection means 144 is composed of, for example, an element such as a CCD in which photosensors are arranged one-dimensionally or two-dimensionally, and each photosensor separates the interference light L4 separated as described above for each wavelength band. It comes to detect.

  The light detection means 144 is connected to an image acquisition means 250 made up of a computer system such as a personal computer, for example, and the image acquisition means 250 is connected to a display device 260 made up of a CRT, a liquid crystal display device or the like.

  The operation of the optical tomographic imaging apparatus 1 having the above configuration will be described below. When acquiring a tomographic image, the optical path length is adjusted so that the measurement target Sb is positioned within the measurable region by first moving the base 23 in the direction of arrow A. Thereafter, the light La is emitted from the light source unit 210, and this light La is split by the light splitting means 3 into the measurement light L1 and the reference light L2. The measurement light L1 is emitted from the optical probe 10 into the body cavity and irradiated to the measurement object Sb. At this time, the measurement light L1 emitted from the optical probe 10 operating as described above scans the measurement object Sb in one dimension. Then, the reflected light L3 from the measuring object Sb is combined with the reference light L2 reflected by the reflecting mirror 22, and the interference light L4 between the reflected light L3 and the reference light L2 is detected by the interference light detection means 240. The detected interference light L4 is subjected to appropriate waveform compensation and noise removal in the image acquisition means 250 and then subjected to Fourier transform, thereby obtaining reflected light intensity distribution information in the depth direction of the measuring object Sb.

  When the measurement light L1 is scanned on the measurement target Sb by the optical probe 10 as described above, information in the depth direction of the measurement target Sb is obtained at each portion along the scanning direction. A tomographic image of a tomographic plane including The tomographic image acquired in this way is displayed on the display device 260. For example, by moving the optical probe 10 in the left-right direction in FIG. 6 and causing the measuring object Sb to scan the measuring light L1 in a second direction orthogonal to the scanning direction, this second It is also possible to obtain a tomographic image of a tomographic plane including the direction.

  Next, another example of the optical tomographic imaging apparatus to which the optical probe according to the present invention is applied will be described. An optical tomographic imaging apparatus 300 shown in FIG. 7 acquires a tomographic image to be measured by the above-described SS-OCT measurement. Specifically, the optical tomographic imaging apparatus 300 differs from the optical tomographic imaging apparatus 1 of FIG. It is the structure of a unit and an interference light detection means.

  The light source unit 310 in this apparatus emits laser light La while sweeping the frequency at a constant period. Specifically, the light source unit 310 includes a semiconductor optical amplifier (semiconductor gain medium) 311 and an optical fiber FB10, and the optical fiber FB10 is connected to both ends of the semiconductor optical amplifier 311. The semiconductor optical amplifier 311 has a function of emitting weak emission light to one end side of the optical fiber FB10 and amplifying light incident from the other end side of the optical fiber FB10 by injection of driving current. When a drive current is supplied to the semiconductor optical amplifier 311, pulsed laser light La is emitted to the optical fiber FB 1 by an optical resonator formed by the semiconductor optical amplifier 311 and the optical fiber FB 10. .

  Further, an optical branching unit 312 is coupled to the optical fiber FB10, and a part of the light guided in the optical fiber FB10 is emitted from the optical branching unit 312 to the optical fiber FB11 side. Light emitted from the optical fiber FB11 is reflected by a rotating polygon mirror (polygon mirror) 316 via a collimator lens 313, a diffraction grating element 314, and an optical system 315. The reflected light enters the optical fiber FB11 again via the optical system 315, the diffraction grating element 314, and the collimator lens 313.

  Here, the rotating polygon mirror 316 is rotated in the direction of the arrow R1, and the angle of each reflecting surface changes with respect to the optical axis of the optical system 315. As a result, only the light in a specific frequency region out of the light dispersed by the diffraction grating element 314 returns to the optical fiber FB11 again. The frequency of light returning to the optical fiber FB11 is determined by the angle between the optical axis of the optical system 315 and the reflecting surface. Then, light in a specific frequency range incident on the optical fiber FB11 is incident on the optical fiber FB10 from the optical splitter 312. As a result, laser light La in a specific frequency range is emitted to the optical fiber FB1 side. .

  Therefore, when the rotary polygon mirror 316 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. Thus, the wavelength-swept laser beam La is emitted from the light source unit 310 to the optical fiber FB1 side.

  The interference light detection means 240 detects the interference light L4 between the reflected light L3 combined by the multiplexing means 4 and the reference light L2. Then, the image acquisition means 250 detects the intensity of the reflected light L3 at each depth position of the measurement target Sb by Fourier transforming the interference light L4 detected by the interference light detection means 240, and the tomogram of the measurement target Sb. Get an image. The acquired tomographic image is displayed on the display device 260. The apparatus of this example has a mechanism that guides the light obtained by dividing the interference light L4 into two by the optical fiber coupler 3 to the photodetectors 40a and 40b, and performs balance detection in the calculation means 241. As described above, in this example, the interference light detection means 240 is configured by the photodetectors 40a and 40b and the calculation means 241.

  Here, the detection of the interference light L4 and the generation of the image in the interference light detection means 240 and the image acquisition means 250 will be briefly described. Details of this point are described in “Mitsuo Takeda,“ Optical Frequency Scanning Spectrum Interference Microscope ”, Optical Technology Contact, 2003, Vol. 41, No. 7, p426-p432”.

When the measurement light L1 is irradiated onto the measurement object Sb, interference fringes with respect to each optical path length difference l when the reflected light L3 and the reference light L2 from each depth of the measurement object Sb interfere with each other with various optical path length differences. S (l) is the light intensity I (k) detected by the interference light detection means 240,
^{_{I (k) = ∫ 0 ∞}} S (l) [1 + cos (kl)] dl
It is represented by Here, k is the wave number, and l is the optical path length difference. It can be considered that the above equation is given as an interferogram in the optical frequency domain with the wave number k = ω / c as a variable. For this reason, in the image acquisition means 250, the spectral interference fringes detected by the interference light detection means 240 are subjected to Fourier transform, and the light intensity S (l) of the interference light L4 is determined, so that from the measurement start position of the measurement object Sb. Distance information and reflection intensity information can be acquired, and a tomographic image can be generated.

  Also in this optical tomographic imaging apparatus 300, the optical probe 10 having the same configuration as that used in the apparatus of FIG. 6 is used, and the operation thereof is the same as that in the apparatus of FIG.

  Next, still another example of the optical tomographic imaging apparatus to which the optical probe according to the present invention is applied will be described. An optical tomographic imaging apparatus 400 shown in FIG. 8 acquires a tomographic image to be measured by the above-described TD-OCT measurement, and includes a light source unit 210 including a light source 111 and a condenser lens 112 that emit laser light La. And a light splitting means 2 for splitting the laser light La emitted from the light source unit 210 and propagating through the optical fiber FB1, and a light splitting means 3 for splitting the laser light La passing therethrough into the measuring light L1 and the reference light L2. The optical path length adjusting means 220 for adjusting the optical path length of the reference light L2 split by the light splitting means 3 and propagated through the optical fiber FB3, and the measurement light L1 split by the light splitting means 3 and propagated through the optical fiber FB2 An optical probe 10 that irradiates the measurement object Sb, and a multiplexing means 4 (light) that combines the reflected light L3 and the reference light L2 from the measurement object when the measurement light S1 is irradiated from the optical probe 10 to the measurement object Sb. Dividing means 3 also serves When, and a interference light detecting means 240 detects interference light L4 of the reference light L2 are multiplexed and the reflected light L3 by combining means 4.

  The optical path length adjusting means 220 is a mirror that is movable in the direction of arrow A in the figure so as to change the distance between the collimator lens 21 that collimates the reference light L2 emitted from the optical fiber FB3 and the collimator lens 21. 23 and mirror moving means 24 for moving the mirror 23, and has a function of changing the optical path length of the reference light L2 in order to change the measurement position in the measurement object Sb in the depth direction. . Then, the reference light L 2 whose optical path length has been changed by the optical path length adjusting means 220 is guided to the multiplexing means 4.

  The interference light detection means 240 detects the light intensity of the interference light L4 that has propagated from the multiplexing means 4 through the optical fiber FB2. Specifically, when the difference between the total optical path length of the measurement light L1 and the reflected light L3 reflected or backscattered at a point where the measurement target Sb is present and the optical path length of the reference light L2 is shorter than the coherence length of the light source Only an interference signal with an amplitude proportional to the amount of reflected light is detected. Further, by scanning the optical path length by the optical path length adjusting unit 220, the reflection point position (depth) of the measurement target Sb from which the interference signal is obtained changes, and accordingly, the interference light detection unit 240 detects the measurement target Sb. The reflectance signal at each measurement position is detected. The information on the measurement position is output from the optical path length adjustment unit 220 to the image acquisition unit. Then, based on the information of the measurement position in the mirror moving unit 24 and the signal detected by the interference light detection unit 240, the reflected light intensity distribution information in the depth direction of the measurement target Sb is obtained by the image acquisition unit 250.

  When the measurement light L1 is scanned on the measurement target Sb by the optical probe 10 as described above, information in the depth direction of the measurement target Sb is obtained at each portion along the scanning direction. A tomographic image of a tomographic plane including The tomographic image acquired in this way is displayed on the display device 260. For example, by moving the optical probe 10 in the left-right direction in FIG. 6 and causing the measuring object Sb to scan the measuring light L1 in a second direction orthogonal to the scanning direction, this second direction is changed. It is also possible to further acquire a tomographic image of the tomographic plane including it.

  Also in this optical tomographic imaging apparatus 400, the optical probe 10 having the same configuration as that used in the apparatus of FIG. 6 is used, and the operation thereof is the same as in the apparatus of FIG.

  As described above, the optical tomographic imaging apparatus 1, 300, 400 using the optical probe 10 has been described. Instead of the optical probe 10, the optical probes 100, 120, according to another embodiment of the present invention described above, It is of course possible to use 140.

1 is a partially broken side view showing an optical probe according to a first embodiment of the present invention. 1 is an overall perspective view of an optical tomographic imaging apparatus to which the optical probe of FIG. 1 is applied. Partially broken side view showing an optical probe according to a second embodiment of the present invention Partially broken side view showing an optical probe according to a third embodiment of the present invention Partially broken side view showing an optical probe according to a fourth embodiment of the present invention Schematic configuration diagram showing an example of an optical tomographic imaging apparatus by SD-OCT measurement using the optical probe of the present invention Schematic configuration diagram showing an example of an optical tomographic imaging apparatus using SS-OCT measurement using the optical probe of the present invention Schematic configuration diagram showing an example of an optical tomographic imaging apparatus based on TD-OCT measurement using the optical probe of the present invention

Explanation of symbols

10, 100, 120, 140 Optical probe
11 Probe outer tube
12 Internal space
13 Optical fiber
14a, 14b gear
15 Motor
17 Prism mirror
18 Rod lens (light collecting means)
112 Sealing member
121 Fiber holder
141 Pressure adjustment means
162 Balloon L Light

Claims (5)

A cylindrical probe outer tube,
An optical fiber disposed in the axial direction of the probe outer cylinder in the inner space of the probe outer cylinder;
Condensing means for condensing the light emitted from the tip of the optical fiber and converging it on the scanned body arranged outside the probe outer cylinder, and sealing the optical fiber in a pressure higher than atmospheric pressure An optical probe comprising: a sealing member. The probe according to claim 1, wherein the probe outer cylinder functions as the sealing member. 3. The optical probe according to claim 1, further comprising pressure adjusting means for adjusting the pressure in the sealing member to be substantially constant. 4. The optical probe according to claim 3, further comprising a telescopic balloon provided on an outer wall surface of the probe outer cylinder, wherein the pressure adjusting means controls expansion / contraction of the balloon. A light source that emits 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 intensity of the reflected light at a plurality of depth positions of the measurement object is detected, and the tomography of the measurement object is detected based on the intensity of the reflected light at each depth position. In an optical tomographic imaging apparatus comprising an image acquisition means for acquiring an image,
An optical tomographic imaging apparatus, wherein the irradiation optical system is configured to include the optical probe according to any one of claims 1 to 4.

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