JP2006215005A - Optical tomographic imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent fluctuations in a measuring range caused by the length irregularities of respective probes, even when a plurality of the probes are replaced to be used in optical coherence tomography measurement. <P>SOLUTION: The optical tomographic imaging system 1 is equipped with a first light path length altering means 50 for altering the light path length of reference light L2, in order to alter the measuring position in the depth direction of a measuring target S and a second light path length altering means 60 for altering the light path length of the reference light so that a measurable region MR, due to the alteration of the light path length in the first light path length altering means 50, becomes a preset measuring region MRref at the attachment of a replaceable probe 10 in order to correct the error in the length of the probe 10 attached to a body 1A. <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 include a forceps port, and a probe introduced into the body cavity from the forceps port via a forceps channel can perform biopsy and treatment of tissue in the body cavity.

  As the above-described endoscope apparatus, an ultrasonic tomographic image acquisition apparatus using ultrasonic waves is known, but an optical tomographic image acquisition apparatus using optical interference using low coherence light, for example, may be used. ing. (For example, refer to Patent Document 1.) In the optical tomographic imaging apparatus of Patent Document 1, after the low-coherence 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, 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 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.

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. The probe includes an optical fiber that guides the measurement light and a mirror that is disposed at the tip of the optical fiber and reflects the measurement light at a right angle. Then, measurement light is irradiated from the probe to the measurement object in the body cavity, and the reflected light from the measurement object is guided again to the multiplexing means through the optical fiber of the probe.
JP 2002-200037 A

  The above-described OCT measurement is a measurement method that utilizes the fact that interference light is detected when the optical path lengths of the measurement light, reflected light, and reference light coincide with each other, and is measured by changing the optical path length of the reference light. The measurement position (measurement depth) with respect to the object is changed.

  By the way, when performing OCT measurement by inserting a probe into a body cavity as shown in Patent Document 1, it is necessary to disinfect and clean the probe after use, so the probe can be attached to and detached from the main body of the optical tomographic imaging apparatus. Is provided. That is, a plurality of probes used in the optical tomographic imaging apparatus are prepared, and the probes can be replaced for each measurement.

  However, since the lengths of the plurality of probes described above, particularly the length of the optical fiber, vary due to manufacturing errors, the optical path lengths of the measurement light and the reflected light vary from probe to probe. The width is limited to a certain range. As a result, there is a problem that the measurement region is shifted for each probe, and an optical tomographic image is acquired in a state where the measurement region is shifted each time the probe is replaced.

  Accordingly, an object of the present invention is to provide an optical tomographic imaging apparatus capable of preventing a change in measurement range due to a variation in the length of each probe even when a plurality of probes are used in replacement. To do.

  The optical tomographic imaging apparatus of the present invention is an optical tomographic imaging apparatus in which a probe that guides measurement light to a measurement target is detachably attached to a main body that acquires an optical tomographic image of the measurement target. A light source that emits low coherence light, a light splitting unit that splits the low coherence light emitted from the light source into measurement light and reference light, and an optical path length change that changes the optical path length of the reference light split by the light splitting unit And means for combining the reflected light from the measurement object when the measurement light is irradiated from the probe and the reference light whose optical path length has been changed by the optical path length changing means, and multiplexing means Interference light detecting means for detecting the interference light between the reflected light and the reference light combined by the optical path length changing means is used for changing the measurement position in the depth direction of the measurement target. The first optical path length that changes the optical path length of light Further, in order to correct the error in the length of the probe attached to the main body and the probe, a region where measurement can be performed by changing the optical path length in the first optical path length changing means when the probe is attached is set in advance. A second optical path length changing unit that changes the optical path length of the reference light so as to be in the set measurement region is provided.

  In addition, the probe may be any probe that guides the measurement light to the measurement target, but may have a unique ID number for each probe.

  Furthermore, the optical tomographic imaging apparatus may further include drive control means for controlling the amount of change of the optical path length in the second optical path length changing means. At this time, the drive control means includes a table storing the amount of change of the optical path length by the second optical path length changing means for each ID number, and when the ID number of the probe attached to the main body is input, the ID number The second optical path length changing means may be controlled so that the optical path length is changed by the change amount of the optical path length stored in association with the.

  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 optical path length changing means includes 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 target, and the main body. In order to correct an error in the length of the attached probe, an area in which measurement is possible due to a change in the optical path length by the first optical path length changing means when the probe is attached is set to a preset measurement area. And a second optical path length changing unit that changes the optical path length of the reference light, so that when the plurality of probes are used in the optical tomographic imaging apparatus, the measurement light and the reflection due to the length variation of each probe are used. Even when the optical path length varies, the second optical path length changing means can adjust the length of the optical path length of the reference light in accordance with the variation. Measured by It is possible to prevent a range variation of. In particular, by using two optical path length changing means to prevent variation in the measurement range due to variations in the length of each probe, the measurable area and the set measurement area can be made to coincide with each other accurately.

  Note that when the ID number of the probe attached to the main body is input to the drive control means, the second optical path length is changed so that the optical path length is changed by the change amount of the optical path length stored in association with the ID number. By controlling the changing means, it is possible to automatically adjust the optical path length of the reference light, so that it is possible to efficiently prevent fluctuations in the measurement range due to variations in the length of each 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 schematic external view showing a preferred embodiment of the optical tomographic imaging apparatus of the present invention. The optical tomographic imaging apparatus 1 includes a main body 1A that acquires a tomographic image of a measurement target by optical coherence tomography measurement, and a probe 10 that is detachably attached to the main body and guides measurement light to the measurement target. . A plurality of probes 10 used for the main body 1A are prepared, and the probe 10 can be removed for cleaning and disinfection.

  FIG. 2 is a block diagram showing a preferred embodiment of the optical tomographic imaging apparatus of the present invention. The main body 1A of the optical tomographic imaging apparatus 1 includes a light source 2 that emits low-coherent light L, light splitting means 3 that splits the low-coherent light L emitted from the light source 2 into measurement light L1 and reference light L2, From the probe 10 for guiding the measuring light L1 divided by the light dividing means 3 to the measuring object S, the optical path length changing means 40 for changing the optical path length of the reference light L2 divided by the light dividing means 3, and the probe 10 A multiplexing means 7 for multiplexing the reflected light L3 from the measurement object when the measurement light L1 is applied to the measurement object S and the reference light L2a whose optical path length has been changed by the optical path length changing means 40; Interference light detecting means 70 for detecting the interference light between the reflected light L3 combined by the means 7 and the reference light L2 is provided.

  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. Here, FIG. 3 is a cross-sectional view showing the tip portion 10A of the probe, and the probe 10 will be described with reference to FIGS.

  The probe 10 is inserted into a body cavity from a forceps opening through a forceps channel, for example, 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. 2 changes the optical path length of the reference light L2 and slightly shifts 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.

  As described above, the probe 10 includes the optical fiber FB10 and is configured to be detachable from the rotation drive unit 30. The length FBL of the optical fiber FB10 is manufactured so that any probe 10 has a specified length. However, the length of the optical fiber FB10 varies due to, for example, a manufacturing error of several mm. . Alternatively, the length of the optical connector 18 may also vary due to a manufacturing error of several millimeters.

  On the other hand, in OCT measurement, measurement is performed in units of several μm, and the manufacturing error of the optical fiber FB10 becomes large for the OCT measurement apparatus. If one probe 10 is used for only one optical tomographic imaging apparatus 1, the optical path length including the manufacturing error of the optical fiber FB10 can be managed when the optical tomographic imaging apparatus 1 is assembled. However, in actuality, since it is necessary to clean the probe 10 at each examination, it is necessary to use a plurality of probes 10, and the optical path lengths of the measurement light L1 and the reflected light L3 are shifted each time the probe 10 is replaced. End up. As a result, every time the probe 10 is replaced, an optical tomographic image with a different measurement region is acquired.

  Specifically, as shown in FIG. 6, when the probe 10 is attached, the setting measurement region MRref that should be able to be measured by the change of the optical path length in the first optical path length changing means 50 is from the probe 10 as shown in FIG. It is assumed that the range is set up to the distance D1. Here, when the length of the optical fiber FB10 of the probe 10 is long by De due to a manufacturing error, the optical path lengths of the measurement light L1 and the reflected light L3 are each long by De. Therefore, the measurable region MR that can detect the interference light between the reflected light L3 and the reference light L2 is shifted from the set measurement region MRref by De, and if measurement is performed in this state, A tomographic image having an error corresponding to the depth direction and De is displayed.

  Therefore, in order to correct an error in the length of the probe 10 attached to the main body 1A in addition to the first optical path length changing unit 50 that changes the optical path length of the reference light L2, the optical path length changing unit 40 The second optical path length changing means for changing the optical path length of the reference light L2 so that the measurable area MR due to the change of the optical path length in the first optical path length changing means 50 becomes the preset set measurement area MRref at the time of attachment. 60 is provided.

  FIG. 7 is a schematic diagram showing an example of the first optical path length changing means 50, and FIG. 8 is a schematic diagram showing an example of the second optical path length changing means 60. The first optical path length will be described with reference to FIGS. 7 and 8. The changing unit 50 and the second optical path length changing unit 60 will be described.

  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 from the dispersive element 52 to the reflector 55 side, and again passes through the dispersive element 52, the Fourier transform lens 53, the scanning mirror 54, the Fourier transform lens 53, and the dispersive element 52 from the reflector 55 to the optical fiber. Incident on FB40.

  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 makes the reference light L2 guided by the optical fiber FB4 parallel light, a corner cube 62 that reflects the reference light L2 made parallel light by the collimator lens 61, After the reference light L2 reflected by the corner cube 62 is converted into parallel light, the collimator lens 63 is emitted to the optical fiber FB40 side. 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 in the first optical path length changing means 50, the frequency-shifted reference light L2a is incident again on the second optical path length changing means 60 through the optical fiber FB40, and the optical fiber FB4. It is made to enter into the multiplexing means 7 via.

  When the probe 10 has become longer due to manufacturing errors (see FIG. 6), the corner cube 62 of the second optical path length changing means 60 moves in the direction of the arrow A2, thereby shortening the optical path length of the reference light L2. In the second optical path length changing means 60 of FIG. 8, when the distance between the collimator lenses 61 and 63 and the corner cube 62 changes by ΔA, the reference light L2 is changed to 2ΔA when entering the first optical path length changing means 50. And is delayed by 2ΔA when guided from the first optical path length changing means 50 to the multiplexing means 7 via the second optical path length changing means 60. As a result, the optical path length of the reference light L2 is only 4ΔA. Change. Therefore, the measurable area MR and the set measurement area MRref can be matched with a small amount of movement by the corner cube 62 moving in the arrow A2 direction based on the relationship of De = 2ΔA. In addition, although the case where the length of the optical fiber FB2 of the probe 10 is longer than the predetermined length is illustrated, the corner cube 62 may be similarly moved in the direction of the arrow A1 even when the length is short.

  As described above, when the plurality of probes 10 are replaced and used, even if the optical path lengths of the measurement light L1 and the reflected light L3 vary due to variations in the length of each probe 10, the second optical path length. Since the length of the optical path length of the reference beams L2 and L2a can be adjusted according to the variation by the changing unit 60, the length of each probe 10 can be changed even when a plurality of probes 10 are used. Variations in the measurement range due to variations can be prevented.

  In particular, by using the two optical path length changing means 50 and 60, it is possible to accurately prevent the measurement range from being fluctuated due to variations in the length of each probe 10. That is, as in a normal OCT apparatus, there is only one optical path length changing means, and the length variation of each probe 10 is changed by changing the distance between this optical path length changing means and the light splitting means / multiplexing means. It is also conceivable to prevent fluctuations in the measurement range due to. However, in this case, the entire optical path length changing means must be moved. Since OCT measurement is performed in units of μm, this moving amount is also required to have an accuracy in units of μm, and it is difficult to suppress variation by moving the entire optical path length changing unit. On the other hand, by using the two optical path length changing means 50 and 60, the corner cube 62 can be moved with high accuracy in units of μm. Variations can be prevented.

  The change of the optical path length by the second optical path length changing unit 60 described above may be such that, for example, a user who views a tomographic image acquired by the user gives an instruction to the drive control unit 100 via an input unit (not shown). The drive control means 100 as shown below may automatically change the optical path length in accordance with the probe ID number.

  That is, each probe 10 is given a unique ID number, and the ID number is input to the drive control means 100 when the probe 10 is attached to the main body 1A of FIG. Here, the input of the ID number may be input by the user to the drive control means 100 using an input means (not shown), or the probe 10 has a storage means for storing the ID number. May be input to the drive control means 100 from the storage means via the rotary drive unit 30 when the is connected to the rotary drive unit 30.

  On the other hand, the drive control means 100 stores the optical path length change amount for correcting the length variation for each probe 10 in a state associated with the ID number. Then, when the ID number is input, the drive control unit 100 reads the change amount of the optical path length associated with the ID number, and changes the second optical path length so that the optical path length is changed by the read change amount. The changing means 60 is controlled. As a result, the work of matching the measurable region MR and the set measurement region MRref can be automatically performed, and therefore the variation in the measurement range due to the variation in the length of each probe 10 can be efficiently prevented.

  According to the above embodiment, in addition to the first optical path length changing unit 50, 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 measuring object S. In order to correct an error in the length of the probe 10 attached to the main body 1A, a set measurement in which a measurable region MR is set in advance by changing the optical path length in the first optical path length changing means 50 when the probe 10 is attached. By providing the second optical path length changing means for changing the optical path length of the reference light so as to be in the region MRref, when a plurality of probes 10 are used in the optical tomographic imaging apparatus 1 for replacement, the length of each probe 10 is changed. Even when the optical path lengths of the measurement light L1 and the reflected light L3 are varied due to the variation in length, the second optical path length changing unit 60 adjusts the length of the optical path length of the reference light L2 according to the variation. It is possible, even when used in replacing a plurality of probes 10, it is possible to prevent variation of the measurement range due to variations in the length of each probe 10.

  Further, as shown in FIG. 7, if the first optical path length changing means 50 is an optical delay means provided with a Fourier transform lens 53 and a scanning mirror 54 for providing a group delay or a phase delay after dispersing the reference light L2. In addition, the frequency shift and the change of the optical path length can be controlled independently, and the speed of the change of the optical path length can be increased.

  Further, as shown in FIG. 8, the second optical path length changing means 60 changes the optical path length of the reference light L2 by the corner cube 62 that reflects the reference light L2 moving in the optical axis direction of the reference light L2. If so, 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. 2, light is transmitted using optical fibers FB1 to FB6, but it may be guided in the air. Even in this case, since the optical fiber FB10 is used in the probe 10, the measurable range and the set measurement range can be matched by changing the optical path length in the second optical path length changing unit 60.

  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. 8 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.

  In the second optical path length changing means 260 of FIG. 11, a refractive index variable element 261 is provided between the collimator lenses 61 and 63 and the corner cube 62, and the refractive index is adjusted by applying a voltage to the refractive index variable element 261. By changing it, 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 schematic external view showing a preferred embodiment of the optical tomographic imaging apparatus of FIG. 1 is a block diagram showing a preferred embodiment of an optical tomographic imaging apparatus of the present invention. 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 how the measurable area changes due to variations in probe length 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 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 1A Main body 2 Light source 3 Light splitting means 6 Optical path length changing means 7 Multiplexing means 10 Probe 40 Optical path length changing means 50, 150 First optical path length changing means 51 Collimator lens 52 Dispersive element 53 Fourier transform lens 54 Scanning mirror 55 Reflector 60, 160, 260, 360 Second optical path length change means 70 Interference light detection means 100 Drive control means 150 Optical path length change means FB10 Optical fiber L Low coherent light L1 Measurement light L2, L2a Reference light L3 Reflected light MR measurable area MRref setting measurement area

Claims (4)

An optical tomographic imaging apparatus for performing measurement by detachably attaching a probe that guides measurement light to a measurement target on a main body that acquires an optical tomographic image of the measurement target,
The body is
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;
Multiplexing means for multiplexing the reflected light from the measurement object when the measurement light is irradiated from the probe 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 multiplexed 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;
In order to correct an error in the length of the probe attached to the main body, a region where measurement can be performed by changing the optical path length in the first optical path length changing unit when the probe is attached is set in advance. An optical tomographic imaging apparatus comprising: a second optical path length changing unit that changes an optical path length of the reference light so as to be in a set measurement region. Drive control means for controlling the change amount of the optical path length in the second optical path length change means, wherein the probe is assigned a unique ID number for each probe, and the drive control When the means is provided with a table storing the amount of change of the optical path length by the second optical path length changing means for each ID number, when the ID number of the probe attached to the main body is input, the ID 2. The optical tomographic imaging apparatus according to claim 1, wherein the second optical path length changing unit is controlled so that the optical path length is changed by an amount of change of the optical path length stored in association with the number. . 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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