JP2006212355A - Optical computed tomography imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set a measurable region to an optional depth in optical coherence tomography measurement. <P>SOLUTION: An optical computed tomography imaging device is provided with a second optical path length change means 60 for changing the optical path length of reference light L2 so as to change the measurable region MR by a first optical path length change means 50 separately from the first optical path length change means 50 for changing the optical path length of the reference light so as to change a measurement position in the depth direction of a measured object at the time of performing the optical coherence tomography measurement. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical tomographic imaging apparatus that acquires an optical tomographic image by OCT (Optical Coherence Tomography) measurement.

  Conventionally, as an endoscope apparatus for observing the inside of a body cavity of a living body, an electronic endoscope apparatus that captures an image of a living body using reflected light reflected from a living body irradiated with illumination light and displays the image on a monitor or the like is widely used. It is used in various fields. Many endoscopes are provided with forceps ports, and biopsy and treatment of tissues in the body cavities can be performed with probes inserted into the body cavities from the forceps ports via the forceps channels.

  As the above-described endoscope apparatus, an ultrasonic tomographic image acquisition apparatus using ultrasonic waves is known, but it is also conceivable to use an optical tomographic image acquisition apparatus using optical interference by low coherent light, for example. Yes. (For example, refer to Patent Document 1.) In the optical tomographic imaging apparatus of Patent Document 1, after the low-coherent light emitted from the light source is divided into the measurement light and the reference light, the measurement light is irradiated to the measurement object and measured. Reflected light from the object is guided to the multiplexing means. On the other hand, the reference light is guided to the multiplexing means after the optical path length is changed in order to change the measurement depth in the measurement object. Then, the reflected light and the reference light are combined by the combining means, and the interference light resulting from the combination is measured by heterodyne detection or the like to obtain an optical tomographic image.

Here, a probe is used that is inserted into a body cavity from a forceps port of an endoscope through a forceps channel when irradiating a measurement object with measurement light. Then, measurement light is irradiated from the probe to the measurement object in the body cavity, and reflected light from the measurement object is guided again to the multiplexing means through the probe.
JP 2002-200037 A

  For example, when a tomographic image such as an eyeball or a sample of a biological tissue is acquired, the measurement target can be moved, so that a site where a tomographic image is desired to be acquired can be easily placed in the measurable region. However, when acquiring a tomographic image using a probe as in Patent Document 1, the living body in the body cavity cannot be moved with respect to the probe, so that positioning of the probe and the measurement target is difficult, and the measurement target There is a problem that it is difficult to obtain an optical tomographic image.

  Further, since the depth that can be measured in the conventional OCT measurement is several millimeters, for example, when a tomographic image of the stomach wall is to be acquired, the stomach wall can be placed in a measurable region due to the presence of a mucous membrane or the like on the stomach wall surface. This may cause a problem that the tomographic image cannot be acquired.

  Therefore, an object of the present invention is to provide an optical tomographic imaging apparatus that can set a measurable region at an arbitrary depth.

  An optical tomographic imaging apparatus according to the present invention is an optical tomographic imaging apparatus that acquires a tomographic image of a measurement object, and includes a light source that emits low-coherence light, and low-coherence light emitted from the light source as measurement light and reference light. A light splitting unit that splits the optical path length of the reference light split by the light splitting unit, reflected light from the measurement target when the measurement light is irradiated on the measurement target, and an optical path A combining means for combining the reference light whose optical path length has been changed by the length changing means; and an interference light detecting means for detecting the interference light between the reflected light combined by the combining means and the reference light. The optical path length changing means measures the first optical path length changing means for changing the optical path length of the reference light in order to change the measurement position in the depth direction of the measurement object, and the change in the optical path length in the first optical path length changing means. To change the measurable area It is characterized in that is obtained and a second optical path length changing means for changing the optical path length of the reference light.

  Here, when irradiating the measurement object with the measurement light, a probe having an optical fiber that guides the reference light divided by the light dividing means to the measurement object and a tube that covers the optical fiber is used. Also good.

  The first optical path length changing means disperses the reference light, for example, regardless of its configuration as long as the optical path length of the reference light is changed in order to change the measurement position in the depth direction of the measurement target. Later, an optical delay means including a scanning mirror and a Fourier transform lens for providing a group delay or a phase delay may be used.

  Further, the second optical path length changing means is not limited in its configuration as long as it changes the optical path length of the reference light in order to change the measurable region by the first optical path length changing means. In order to change the measurement position in the vertical direction, the reference light can be changed by moving the mirror that reflects the reference light in the optical axis direction of the reference light, regardless of the configuration, as long as the optical path length of the reference light is changed. The optical path length may be changed.

  According to the optical tomographic imaging apparatus of the present invention, the first optical path length changing means for changing the optical path length of the reference light in order that the optical path length changing means changes the measurement position in the depth direction of the measurement target; In order to change the measurable region in which measurement is possible due to the change in the optical path length in the optical path length changing means, the second optical path length changing means for changing the optical path length of the reference light is provided. Since the measurable area can be set to an arbitrary depth of the measuring object by the changing means, the measuring object can be individually positioned in the measurable area, and the light emission portion of the measuring light in the apparatus and the measuring object Even when another substance is interposed between the two, an optical tomographic image of the measurement object can be acquired.

  In particular, when the probe further includes an optical fiber that guides the reference light split by the light splitting means to the measurement target, and a tube that covers the optical fiber, the probe is inserted into the body cavity for light. Even when the probe cannot be brought into close contact with the measurement target in the body cavity when acquiring the tomographic image, the measurable region can be changed to include the measurement target by the first optical path length changing unit. The optical tomographic image can be efficiently acquired by facilitating the positioning of the probe.

  If the first optical path length changing means is an optical delay means having a scanning mirror and a Fourier transform lens that gives a group delay or a phase delay after dispersing the reference light, an optical path based on a frequency shift due to the phase delay and a group delay. The length change can be controlled independently, and the speed of the optical path length can be increased.

  In addition, if the second optical path length changing unit changes the optical path length of the reference light by moving the mirror that reflects the reference light in the optical axis direction of the reference light, the optical path length of the reference light with a simple configuration. Changes can be made.

  Embodiments of an optical tomographic imaging apparatus according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a preferred embodiment of the optical tomographic imaging apparatus of the present invention. The optical tomographic imaging apparatus 1 acquires an optical tomographic image by OCT (Optical Coherence Tomography) measurement, and measures the light source 2 that emits the low coherent light L and the low coherent light L emitted from the light source 2. The light splitting means 3 that splits the light L1 and the reference light L2, the probe 10 that guides the measurement light L1 split by the light splitting means 3 to the measuring object S, and the reference light L2 split by the light splitting means 3 The optical path length is changed by the optical path length changing means 40 for changing the optical path length of the reflected light L3 from the measuring object when the measuring light L1 is irradiated from the probe 10 onto the measuring object S, and the optical path length changing means 40. A multiplexing unit 7 that combines the reference light L2a, an interference light detection unit 70 that detects interference light between the reflected light L3 combined by the multiplexing unit 7 and the reference light L2, and have.

  Here, the light source 2 includes a laser light source that emits low coherent light such as SLD (Super Luminescent Diode) and ASE (Amplified Spontaneous Emission). The optical tomographic imaging apparatus 1 acquires a tomographic image when the living body in the body cavity is set as the measurement target S. Therefore, attenuation of light due to scattering / absorption when passing through the measurement target S is minimized. For example, it is preferable to use an ultrashort pulse laser light source having a wide spectrum band.

  The light splitting means 3 is composed of, for example, a 2 × 2 optical fiber coupler, and splits the low coherent light L guided from the light source 2 through the optical fiber FB1 into the measurement light L1 and the reference light L2. ing. The light splitting means 3 is optically connected to the two optical fibers FB2 and FB3, respectively, so that the measurement light L1 is guided by the optical fiber FB2 side, and the reference light L2 is guided by the optical fiber FB3 side. It has become.

  The optical fiber FB2 is optically connected to the probe 10, and the measurement light L1 is guided from the optical fiber FB2 to the probe 10. 2 is a perspective view showing the appearance of the probe 10 in FIG. 1, and FIG. 3 is a cross-sectional view showing the tip portion 10A of the probe. The probe 10 will be described with reference to FIGS.

  The probe 10 is inserted into a body cavity through, for example, a forceps opening, and is detachably attached to the rotation drive unit 30 by an optical connector 18. FIG. 3 is a schematic diagram showing an example of the tip portion 10A of the probe 10. As shown in FIG. In FIG. 3, the probe 10 includes a tube 11, an optical fiber FB <b> 10 accommodated in the tube 11, and a prism 17 for emitting the measurement light L <b> 1 guided through the optical fiber FB <b> 10 toward the measurement target S. Yes. The tube 11 is made of a material having flexibility such as resin and having light transmittance, and a cap 12 for sealing the inside of the tube 11 is fixed to a tip portion of the tube 11.

  A flexible shaft 13 is accommodated in the tube 11, and the optical fiber FB <b> 10 is accommodated in the flexible shaft 13. The flexible shaft 13 is composed of, for example, a double contact coil in which a metal wire is wound spirally, and each contact coil is wound so that the winding directions are opposite to each other.

  The distal end of the flexible shaft 13 and the distal end of the optical fiber FB10 are respectively fixed to one end side 14a of the base 14, and a prism 17 is fixed to the other end side 14b of the base 14. Further, a ferrule 15 and a refractive index dispersion lens (Gradient Index Lens) 16 are accommodated in the base 14. Therefore, the reference light L2 emitted from the optical fiber FB10 is guided to the ferrule 15 and the refractive index dispersion lens 16 and enters the prism 17.

  The prism 17 emits the measurement light L1 guided in the optical fiber FB10 to the side wall surface 11a side of the tube 11, and the measurement light L1 passes through the tube 11 and is irradiated to the measurement object. At the same time, the prism 17 receives the reflected light L3 from the measuring object S by the irradiation of the measuring light L1, and emits it to the optical fiber FB10 side.

  Here, the flexible shaft 13 and the optical fiber FB10 are rotatably provided in the arrow R direction with respect to the tube 11, and the base 14 and the prism 17 are also rotated in the arrow R direction with the rotation of the flexible shaft 13 and the optical fiber FB10. It is supposed to be. Therefore, the measurement light L1 emitted from the prism 17 is irradiated to the measurement object S while rotating in the arrow R direction. Thereby, an optical tomographic image in the rotation direction (radial direction) can be acquired in the body cavity.

  FIG. 4 is a cross-sectional view showing an example of the optical connector 18 of the probe 10. The optical connector 18 detachably attaches the probe 10 to the rotary drive unit 30, and includes a cover 19 fixed to the rotary drive unit 30, a fixed sleeve 20 accommodated in the cover 19, and a fixed sleeve 20. And a connection ring 23 for fixing the rotary cylinder 22 and the rotary connector 32 of the rotary drive unit 30 to each other. The cover 19 is fixed to the casing 31 of the rotation drive unit 30 and is provided so as to slide with respect to the fixed sleeve 20. On the other hand, the fixing sleeve 20 is fixed to the cover 19 by a fixing member 21.

  The rotating cylinder 22 is rotatably held with respect to the fixed sleeve 20 via a bearing 22a. The rotary cylinder 22 is fixed to the flexible shaft 13, and the flexible shaft 13 is rotated by the rotation of the rotary cylinder 22. Further, a connection ring 23 is connected to the rotating cylinder 22, and a thread is formed inside the connection ring 23. The connecting ring 23 is fixed to the rotary connector 32 so that the rotary cylinder 22 rotates in synchronization with the rotary connector 32. A ferrule 24 is accommodated in the rotary cylinder 22, and the optical fiber FB10 and the optical fiber FB2 on the rotation drive unit 30 side are optically connected via the ferrule 24 (not shown). .

  FIG. 5 is a cross-sectional view showing an example of the rotary drive unit 30. The rotation drive unit 30 in FIG. 5 rotates the optical fiber FB10 and the prism 17 in the tube 11 in the direction of arrow R, and a housing 31 having a connector insertion port 31a into which the optical connector 18 is inserted. And a rotary connector 32 protruding from the connector insertion port 31a and connected to the optical connector 18, and a motor 35 for rotating the rotary connector 32. The rotary connector 32 rotates in synchronization with the gear 33, and the gear 33 is connected to a gear 34 fixed to the rotating shaft of the motor 35. When the motor 35 is driven, the rotary connector 32 is rotated through the gears 33 and 34. Further, the rotation drive unit 30 is provided with a stopper 36, and the rotation of the rotary connector 32 can be suppressed by pressing the stopper 36 and contacting the gear 33.

  Here, operation examples of the probe 10 and the rotary drive unit 30 will be described with reference to FIGS. First, when the motor 35 is driven in the rotary drive unit 30, the rotary connector 32 rotates, and the rotary cylinder 22 of the probe 10 connected thereto rotates. Furthermore, when the flexible shaft 13 fixed to the rotating cylinder 22 rotates, the optical fiber FB10 and the prism 17 rotate in the arrow R direction. As a result, the measurement light L1 emitted from the prism 17 is irradiated onto the measurement object S while rotating in the arrow R direction. Here, as described above, since the flexible shaft 13 is composed of two close-contact coils whose winding directions are opposite to each other, the rotational force is applied to the base of the tip regardless of the direction of rotation. 14 can be transmitted (see FIG. 4).

  As will be described later, the optical path length changing unit 40 in FIG. 1 changes the optical path length of the reference light L2 and slightly shifts the frequency of the reference light L2 in order to change the measurement position in the measurement target S in the depth direction. In addition to the first optical path length changing means 50 to be provided, it has second optical path length changing means 60 for changing the optical path length of the reference light L2. Then, the reference light L2a whose optical path length has been changed and frequency shifted by the optical path length changing means 40 is guided to the multiplexing means 7 through the optical fibers FB4 and FB5.

  The multiplexing means 7 is composed of a 2 × 2 optical fiber coupler, and combines the reference light L2 frequency-shifted and changed in optical path length by the optical path length changing means 40 and the reflected light L3 from the measuring object S. The light is emitted to the interference light detection means 70 side.

  The interference light detection means 70 is composed of, for example, a heterodyne interferometer or the like, and detects the light intensity of the interference light. Specifically, when the sum of the total optical path length of the measurement light L1 and the total optical path length of the reflected light L3 is equal to the total optical path length of the reference light L2, it is strong and weak at the difference frequency between the reference light L2 and the reflected light L3. A beat signal that repeats is generated. As the optical path length is changed by the first optical path length changing means 50, the measurement position (depth) of the measuring object S changes, so that the interference light detection means 70 detects a plurality of beat signals at each measurement position. . The information on the measurement position is output from the drive control means 100 that controls the operation of the optical path length changing means 40. An optical tomographic image is generated on the basis of the beat signal detected by the interference light detection means 70 and the information on the measurement position in the drive control means 100.

  By the way, when acquiring a tomographic image using the probe 10 as described above, the living body in the body cavity cannot be moved with respect to the probe 10, so that the positioning of the probe 10 and the measuring object S is difficult. Furthermore, since the depth that can be measured in the conventional OCT measurement is several millimeters, for example, when a tomographic image of the stomach wall is to be acquired, the stomach wall is placed in a measurable region by the thickness of the mucous membrane on the wall of the gastrointestinal tract. And a tomographic image cannot be acquired.

  Therefore, the optical path length changing unit 40 is different from the first optical path length changing unit 50 that changes the optical path length of the reference light L2 in order to change the measurement position in the measurement target S in the depth direction. In order to change the region in which measurement is possible due to the change in the optical path length in the length changing means 50, the second optical path length changing means 60 for changing the optical path length of the reference light L2 is provided. Here, FIG. 6 is a schematic diagram showing an example of the first optical path length changing means 50, and FIG. 7 is a schematic diagram showing an example of the second optical path length changing means 60. The first optical path length changing means 60 will be described with reference to FIGS. The 1 optical path length changing means 50 and the 2nd optical path length changing means 60 are each demonstrated.

  First, the first optical path length changing means 50 will be described with reference to FIG. The first optical path length changing means 50 is an optical delay means called “RSOD: Rapid Scanning Optical Delay line”. The detailed principle of this RSOD is described in “Andrew M. Rollins, Manish D. Kulkarni”. , Siavash Yazdanfar, Rujchai Ung-arunyawee and Joseph A. Izatt, “IN vivo video rate optical coherence tomography” Opt. Express 6,219-229 (1998) ”and JP-T-2001-527659.

  The first optical path length changing unit 50 disperses the reference light L2 incident from the optical fiber FB40 via the collimator lens 51 using the dispersive element 52 made of a diffraction grating, and then performs Fourier transform that gives a group delay or a phase delay. The optical delay unit includes a lens 53 and a scanning mirror 54.

  The reference light L2 is incident on the dispersive element 52 at a certain angle. Thereafter, the reference light L <b> 2 passes through the Fourier transform lens 53, is reflected by the scanning mirror 54, passes through the Fourier transform lens 53 again, and enters the dispersive element 52. Then, the reference light L2 is reflected by the reflector 55 by the dispersive element 52, and again enters the optical fiber FB40 through the dispersive element 52, the scanning mirror 54, the Fourier transform lens 53, and the dispersive element 52.

  Here, the scanning mirror 54 is disposed at a position separated by the focal length f of the Fourier transform lens 53, and swings at a high speed in the direction of the arrow σ with the position off the optical axis LL of the Fourier transform lens 53 as the rotation center. It is supposed to be. By changing the amount of tilt of the scanning mirror 54, an optical delay occurs in the reference light L2 transmitted through the Fourier transform lens 53, and the optical path length changes. Note that the optical path length changed by the first optical path length changing unit 50 is, for example, about 2 mm, and the range in which the optical path length changes is a region in which measurement is possible in the depth direction of the measuring object S.

  Further, the amount of frequency shift can be adjusted by changing the phase delay amount by changing the rotation center of the scanning mirror 54. Therefore, the frequency-shifted reference light L2a is incident on the second optical path length changing unit 60 again through the optical fiber FB40.

  By using such first optical path length changing means 50, it is possible to independently control the frequency shift due to the phase delay and the optical path length change due to the group delay, and to increase the speed of the optical path length change. Can do.

  Next, the second optical path length changing means 60 will be described with reference to FIG. The second optical path length changing means 60 includes a collimator lens 61 that converts the reference light L2 guided by the optical fiber FB4 into parallel light, and a corner cube (mirror) that reflects the reference light L2 converted into parallel light by the collimator lens 61. 62, and a collimator lens 63 for emitting the reference light L2 reflected by the corner cube 62 to the optical fiber FB40 side after making it into parallel light. The corner cube 62 is provided so as to be movable in the direction of arrow A, and this movement is controlled by the first drive control means 100. As the corner cube 62 moves in the direction of arrow A, the optical path length of the reference light L2 changes.

  Therefore, the reference light L2 incident on the optical path length changing unit 40 is first incident on the second optical path length changing unit 60 and then incident on the first optical path length changing unit 50 via the optical fiber FB40. After the frequency shift and the optical path length change are performed in the first optical path length changing unit 50, the frequency-shifted reference light L2a is incident again on the second optical path length changing unit 60 through the optical fiber FB40, and the optical fiber FB4 is passed through. Then, the light is incident on the multiplexing means 7.

  Here, when the second optical path length changing unit 60 is in the initial state, the measurable region MR is the optical path of the reference light L2 from the optical axis CL of the probe 10 to the first optical path length changing unit 50 as shown in FIG. The maximum delay amount with respect to the length (for example, D1 = about 2 mm) is set. At this time, when the corner cube 62 of the second optical path length changing unit 60 moves in the direction of the arrow A1 by ΔA (see FIG. 7), the reference light L2 enters the first optical path length changing unit 50 from the second optical path length changing unit 60. In doing so, it is delayed by 2ΔA compared to the initial state. Therefore, as shown in FIG. 8, the measurable region MR is changed to a position away from the center of the optical axis CL by 2ΔA.

  As described above, the second optical path length changing unit 60 changes the optical path length of the reference light L2, so that the measurement target S to be measured in the body cavity cannot be positioned within the measurable region MR in the initial state. However, even if the measurement object S can be positioned in the measurable region MR and another substance is interposed between the measurement object S and the probe 10, the optical tomography of the measurement object S is possible. An image can be reliably acquired.

  An example of the operation of the optical tomographic imaging apparatus 1 of the present invention will be described with reference to FIGS. First, the probe 10 is inserted into a body cavity and positioned at a site where the measurement target S exists. Thereafter, low-coherence light is emitted from the light source 2 to acquire an optical tomographic image. Here, when the operator (measuring person) confirms the acquired optical tomographic image and determines that the measuring object S is not photographed, or when it is desired to acquire an optical tomographic image at a deeper position in the measuring object S. For example, when the operator (measurer) gives an instruction to the drive control means 100 via the input means, the second optical path length changing means 60 changes the optical path length. Then, the measurement position (depth) information of the first optical path length changing means 50 is output from the drive control means 100 that controls the operation of the optical path length changing means 40, and these information and the interference light detecting means 70 are detected. It is possible to form an optical tomographic image that has been changed to a deeper position by using the beat signal of the interference light.

  According to the above embodiment, the optical path length changing unit 40 changes the optical path length of the reference light L2 in order to change the measurement position in the depth direction of the measurement target S. In order to change the measurable area by the first optical path length changing means 50, the second optical path length changing means 60 for changing the optical path length of the reference light L2 is provided, so that the measurement by the first optical path length changing means 50 is performed. The possible region MR can be set to an arbitrary depth of the measuring object S by the second optical path length changing means 60.

  In particular, when the probe 10 as shown in FIGS. 2 and 3 is used, the probe 10 cannot be brought into close contact with the measurement target S in the body cavity when the probe 10 is inserted into the body cavity and an optical tomographic image is acquired. Even in such a case, the measurable region MR can be set so as to include the measurement target S by the first optical path length changing unit 50, and an optical tomographic image can be obtained with certainty.

  Further, as shown in FIG. 6, the first optical path length changing unit 50 disperses the reference light L2 using a dispersive element 52 made of a diffraction grating, and then gives a Fourier transform lens 53 and scanning that gives a group delay or a phase delay. If the optical delay means includes the mirror 54, the frequency shift due to the phase delay and the change of the optical path length due to the group delay can be controlled independently, and the speed of the change of the optical path length can be increased. it can.

  Further, as shown in FIG. 7, the second optical path length changing means 60 moves the corner cube (mirror) 62 that reflects the reference light L2 in the direction of the optical axis of the reference light L2, thereby changing the optical path length of the reference light L2. If it is to be changed, the optical path length of the reference light L2 can be changed with a simple configuration.

  The embodiment of the present invention is not limited to the above embodiment. For example, in FIG. 1, light is transmitted using optical fibers FB1 to FB6, but it may be guided in the air.

  Further, in the probe 10 of FIG. 3, the measurement light L1 guided through the optical fiber FB10 is irradiated onto the measurement object S through the refractive index dispersion lens 16, but in the above-described measurable region MR. A lens that can change the focusing position of the measurement light L1 in accordance with the change may be used instead of the refractive index dispersion lens 16.

  Further, the configuration in which the first optical path length changing unit 50 changes the optical path length by using the dispersive element 52 and the Fourier transform lens 53 is exemplified. For example, from the configuration disclosed in Japanese Patent Application Laid-Open No. 2003-329577. It may be. Specifically, as shown in FIG. 9, the first optical path length changing unit 150 includes a rotatable rotating reflector 151 having a plurality of reflectors and a fixed mirror 152, and the second optical path length changing unit. The reference light L2 guided from the means 60 via the optical fiber FB40 is reflected by the rotary reflector 151 and the fixed mirror 152, whereby the frequency shift and the optical path length are changed.

  Moreover, in the said embodiment, although the 2nd optical path length change means 60 of FIG. 7 illustrates the case where the optical path length is changed by moving the corner cube 62 in the optical axis direction of the reference light L2, the optical path is illustrated. As long as the length is changed, a known technique may be used. For example, the second optical path length changing means 160 in FIG. 10 has two mirrors 161 and 162, and the reference light L2 is repeatedly reflected between the two mirrors 161 and 162. The optical path length is changed by moving the mirror 161 in the arrow α direction.

  Further, in the second optical path length changing means 260 of FIG. 11, a refractive index variable element 261 is provided between the collimators 61 and 63 and the corner cube 62, and the refractive index is changed by applying a voltage to the refractive index variable element 261. Thus, the optical path length of the reference light L2 guided in the variable refractive index element 261 may be changed.

  Furthermore, as shown in FIG. 12, the second optical path length changing unit 360 may include a collimator lens 361 and a mirror 362 that reflects the reference light L <b> 2 that has been collimated by the collimator lens 361. At this time, the reference light L2 reflected by the mirror 362 is guided to the first optical path length changing unit 50 by the optical coupler 270, and the reference light L2a subjected to frequency shift and optical path length change by the first optical path length changing unit 50. Is guided to the optical fiber FB4 (on the multiplexing means 7 side) through the optical coupler 270. As shown in FIG. 13, a beam splitter 280 is used instead of the optical coupler 270 so that the reference light L2 from the first optical path length changing means 50 is incident on the optical fiber FB40 via the collimator lens 290. May be.

1 is a block diagram showing a preferred embodiment of an optical tomographic imaging apparatus of the present invention. The perspective view which shows the external appearance of the probe in the optical tomographic imaging apparatus of FIG. Sectional drawing which shows an example of the front-end | tip part of the probe in the optical tomographic imaging apparatus of FIG. Sectional drawing which shows an example of the connector of the probe in the optical tomographic imaging apparatus of FIG. Sectional drawing which shows an example of the rotational drive unit in the optical tomographic imaging apparatus of FIG. Schematic diagram showing an example of the first optical path length changing means of FIG. Schematic diagram showing an example of the second optical path length changing means of FIG. The schematic diagram which shows a mode that a measurable area | region changes with a 2nd optical path length change means. The schematic diagram which shows another example of the 1st optical path length change means of FIG. The schematic diagram which shows another example of the 2nd optical path length change means of FIG. The schematic diagram which shows another example of the 2nd optical path length change means of FIG. The schematic diagram which shows another example of the 2nd optical path length change means of FIG. The schematic diagram which shows another example of the 2nd optical path length change means of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical tomographic imaging apparatus 2 Light source 3 Light splitting means 6 Optical path length changing means 7 Combined means 10 Probe 40 Optical path length changing means 50, 150 Optical path length changing means 52 Dispersive element 53 Fourier transform lens 54 Scanning mirrors 60, 160, 260, 360 Second optical path length changing means 62 Corner cube (mirror)
70 Interference light detection means 100 Drive control means 151 Rotating reflector 152 Fixed mirror FB10 Optical fiber L Low coherent light L1 Measurement light L2, L2a Reference light L3 Reflected light LL Optical axis MR Measurable region

Claims (4)

In an optical tomographic imaging apparatus that acquires a tomographic image of a measurement object,
A light source that emits low coherence light;
A light splitting means for splitting the low coherence light emitted from the light source into measurement light and reference light;
An optical path length changing means for changing an optical path length of the reference light divided by the light dividing means;
A multiplexing means for multiplexing the reflected light from the measurement object when the measurement light is irradiated to the measurement object and the reference light whose optical path length has been changed by the optical path length changing means;
Interference light detection means for detecting interference light between the reflected light and the reference light combined by the multiplexing means,
The optical path length changing means is
First optical path length changing means for changing the optical path length of the reference light in order to change the measurement position in the measurement object in the depth direction;
Second optical path length changing means for changing the optical path length of the reference light in order to move a measurable region in which measurement is possible by changing the optical path length in the first optical path length changing means within the measurement object; An optical tomographic imaging apparatus comprising: 2. The probe according to claim 1, further comprising: an optical fiber that guides the reference light split by the light splitting means to the measurement target; and a tube that covers the optical fiber. An optical tomographic imaging apparatus according to 1. 3. The optical delay unit according to claim 1, wherein the first optical path length changing unit is an optical delay unit including a scanning mirror and a Fourier transform lens that gives a group delay or a phase delay after dispersing the reference light. Optical tomographic imaging device. 2. The optical path length of the reference light is changed by the mirror that reflects the reference light moving in the optical axis direction of the reference light. 4. The optical tomographic imaging apparatus according to any one of 3 above.

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