JP2011200341A - Endoscope shape detector and endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endoscope shape detector surely detecting strain generated in an optical fiber inserted through an endoscope inserting section without carrying out spectrometry by a spectrometer in an inexpensive constitution suitable for miniaturizing and precisely detecting the shape of endoscope inserting section in a simple procedure.SOLUTION: The endoscope shape detector includes: optical fibers 41A, 41B forming a plurality of FBGs 1; a light source section 49 introducing incident light to the optical fibers 41A, 41B; a light path separating section 55 taking out diffracted return light which is incident light diffracted by the respective FBGs and returning; a light detecting section 59 detecting the taken out diffracted returning light; a light shutter 57 arranged between the light path separating section 55 and the light detecting section 59; and a control section 51 opening the light shutter 57 in sync with timing when the diffracted returning light reaches the light detecting section 59, selectively detecting the diffracted returning light from the specified FBGs, obtaining the strain quantity of the respective FBGs based on the wavelength sift quantity relative to the reference incident light of the detected returning light, and detecting the shape of the endoscope inserting section 19 based on the strain quantity.

Description

  The present invention relates to an endoscope shape detection device that detects the shape of an endoscope insertion portion and an endoscope system including the same.

  In a general endoscope, a long endoscope insertion portion is inserted into a lumen in a body cavity so that an observation site such as a lesion can be diagnosed and treated. However, the shape of the endoscope inserted into the body cavity cannot be easily determined from the outside, and it is impossible to accurately grasp the position in the body cavity where the part being observed is located. In particular, it was difficult to determine how far the endoscope was inserted in a three-dimensionally winding pipe like the small intestine. Therefore, various devices have been proposed that detect the shape of the endoscope insertion portion and grasp the state of insertion into the body cavity from the shape of the endoscope insertion portion.

  For example, in Patent Document 1, an optical fiber having a fiber Bragg grating (FBG), which is a strain sensor, is embedded in an endoscope insertion portion, light is incident from one end side of the optical fiber, and is generated from the FBG. An apparatus is described in which distortion is detected from the amount of wavelength transition of diffracted light, and the shape of the endoscope insertion portion is obtained from the distortion. Similarly, in Patent Document 2, an optical fiber having an FBG is embedded in an endoscope insertion portion, light is incident from one end of the optical fiber, and a missing portion of a specific wavelength component with respect to transmitted light that has passed through the FBG. Describes a device that detects distortion from the amount of wavelength transition and obtains the shape of the endoscope insertion portion.

  However, in any apparatus, the characteristic that the wavelength of the diffracted light by the FBG shifts according to the strain generated in the fiber is used, and an expensive spectrometer having a complicated optical system is used to detect this wavelength transition. Is required. Further, since the spectroscopic analysis is performed by the spectroscope, the procedure for obtaining the amount of distortion becomes complicated, and it is inevitable that the apparatus becomes large. Furthermore, in the method of Patent Document 1, it is necessary to lay a total of four optical fibers, which is disadvantageous for reducing the diameter of the endoscope insertion portion.

Japanese Patent Application Laid-Open No. 2004-251779 JP 2008-173395 A

  According to the present invention, a fiber Bragg grating of each optical fiber is detected by detecting distortion generated in an optical fiber inserted through an endoscope insertion portion with a configuration that is inexpensive and suitable for downsizing without performing spectroscopic analysis by a spectroscope. It is an object of the present invention to provide an endoscope shape detecting device and an endoscope system that can obtain the amount of distortion at the arrangement position of the endoscope and thereby accurately detect the shape of the endoscope insertion portion with a simple procedure.

The present invention has the following configuration.
(1) At least two optical fibers each having a diffraction grating are arranged at different positions along the longitudinal direction of the endoscope insertion portion, and distortions generated in the respective optical fibers due to deformation of the endoscope insertion portion. An endoscope shape detection device that detects the shape of the endoscope insertion portion by obtaining from the diffracted light of the diffraction grating,
Each optical fiber is discretely arranged at a plurality of positions along a fiber axis, each of which includes a pair of diffraction gratings formed by overlapping a first fiber Bragg grating and a second fiber Bragg grating having mutually different diffraction grating periods, It has a birefringence difference in the biaxial direction perpendicular to the fiber axis direction,
A light source unit for introducing incident light including a wavelength corresponding to each diffraction grating period of the diffraction grating pair into the optical fiber;
An optical path separating unit that extracts the diffracted return light that is diffracted and returned by the diffraction grating pair from the incident light introduced into each of the optical fibers; and
A light detection unit for detecting diffraction return light of each of the optical fibers taken out from the optical path separation unit;
An optical shutter disposed in the middle of the optical path between the optical path separator and the light detector;
An optical shutter driving unit that opens and closes the optical shutter and selectively detects the diffracted return light from the specific fiber Bragg grating by the light detection unit;
The first fiber Bragg grating causes the first fiber Bragg grating to diffract the first diffraction return light and the second diffraction return light that are diffracted at mutually different wavelengths according to the birefringence difference, and the incident light is caused to the second fiber Bragg grating. The orthogonal biaxial directions acting on each diffraction grating pair based on each wavelength information including third diffraction return light and fourth diffraction return light diffracted at different wavelengths according to the birefringence difference The amount of strain in the fiber axis direction is obtained for each optical fiber, and the shape of the endoscope insertion portion is detected from the relationship between the position of the diffraction grating pair of each optical fiber and the amount of strain in each direction. An arithmetic processing unit to perform,
An endoscope shape detection apparatus comprising:

(2) An endoscope system for acquiring captured image information of a subject from an imaging means provided on a distal end side of an endoscope insertion portion,
An endoscope shape detection device;
A display unit for displaying the detection information of the shape of the endoscope insertion unit and the captured image information;
Endoscope system equipped with.

  According to the endoscope shape detection device and the endoscope system according to the present invention, the distortion generated in the optical fiber can be detected with a configuration that is inexpensive and suitable for downsizing without performing spectroscopic analysis with a spectroscope. Since the amount of strain at the position where each fiber Bragg grating is arranged is detected, the shape of the endoscope insertion portion can be accurately detected by a simple procedure.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure for describing embodiment of this invention, and is the whole endoscope system block diagram containing an endoscope shape detection apparatus. It is the schematic of the front-end | tip part vicinity of an endoscope insertion part. It is AA sectional drawing of FIG. (A) is sectional drawing of an optical fiber, (B) is a schematic diagram of the diffraction grating pair formed by two fiber Bragg gratings mutually overlapping. It is typical structure explanatory drawing of the fiber Bragg grating formed in the optical fiber. It is a graph which shows the spectral intensity of the 1st-4th diffraction return light diffracted by two fiber Bragg gratings. (A), (B), and (C) are graphs showing a state in which the wavelength width of the diffracted return light from the fiber Bragg grating changes due to strain in a direction orthogonal to the axial direction of the optical fiber. (A), (B), (C) are graphs showing a state in which the wavelength of diffracted return light from the fiber Bragg grating transitions due to axial strain of the optical fiber. It is a flowchart which estimates the shape of an endoscope insertion part by irradiating each diffraction grating pair with the light of a predetermined wavelength. It is a block block diagram which shows the measurement optical system by a shape detection part and an optical fiber. It is a block diagram of an optical shutter. It is a graph which shows the spectral intensity of the pulsed light radiate | emitted from a light source part. It is a control time chart figure by a control part. It is sectional drawing for demonstrating the bending direction of an endoscope insertion part. It is a table | surface which shows the relationship between the detected distortion and the bending direction of an endoscope insertion part. It is explanatory drawing which shows an example of the curved state of an endoscope insertion part. It is a block block diagram which shows the other structural example of a shape detection part. It is a perspective view which shows the treatment tool inserted in the forceps hole of an endoscope insertion part. It is BB sectional drawing of FIG. It is sectional drawing of the other optical fiber in which distortion is measurable.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram for explaining an embodiment of the present invention, and is an overall configuration diagram of an endoscope system 100 including an endoscope shape detection device.

  The endoscope system 100 includes an endoscope 11 and a control device 13 connected to the endoscope 11. The control device 13 includes a display unit 15 such as a monitor, a keyboard as input means (not shown), and the like. Is connected. The control device 13 includes a light source unit that supplies illumination light to the endoscope 11, and a processor unit that performs various image processing on the image pickup signal from the endoscope 11 and converts the image signal into a video signal. A shape detection unit 10 to be described later is incorporated.

  The endoscope 11 includes a main body operation unit 17 and an endoscope insertion unit 19 connected to the main body operation unit 17 and inserted into a body cavity. A universal cord 21 containing various pipes and signal cables is connected to the main body operation unit 17, and a connector 23 detachably connected to the control device 13 is attached to the distal end of the universal cord 21. The connector 23 may be a composite type connector and may be configured to be connected to the light source unit and the processor unit of the control device 13 by individual connectors.

  Light emitted from the light source unit of the control device 13 is supplied to the endoscope 11 through the connector 23 and the universal cord 21 and is transmitted as illumination light to an illumination optical system provided at the distal end of the endoscope insertion unit 19.

  In addition, the imaging optical system provided at the distal end of the endoscope insertion unit 19 includes an imaging element that images an observation site illuminated by the illumination optical system, and controls an imaging signal of an observation image obtained from the imaging element 13 is output. Then, the processor unit of the control device 13 displays image information obtained by performing image processing on the input image pickup signal on the display unit 15. In the series of processing, an instruction can be input from a keyboard or the like connected to the control device 13. A CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor is used as an imaging element of the imaging optical system.

  Various buttons 25 such as an air supply / water supply button, a suction button, a shutter button, a function switching button and the like are arranged in parallel on the main body operation unit 17 of the endoscope 11 and a bending operation is performed on the distal end side of the endoscope. A pair of angle knobs 27 are provided.

  The endoscope insertion unit 19 includes a flexible portion 31, a bending portion 33, and a distal end portion (endoscope distal end portion) 35 in order from the main body operation unit 17 side. The flexible portion 31 has flexibility and is continuously provided on the proximal end side of the bending portion 33, and the bending portion 33 is turned in the endoscope insertion portion 19 by rotating the angle knob 27 of the main body operation portion 17. The wire (not shown) inserted in the cable is pulled to bend. Thereby, the endoscope front-end | tip part 35 can be orient | assigned to a desired direction.

  A forceps insertion portion 39 into which a treatment tool such as forceps is inserted is provided in the connecting portion 37 between the main body operation portion 17 and the endoscope insertion portion 19, and the treatment tool inserted from the forceps insertion portion 39 is It is led out from a forceps opening (not shown) of the endoscope distal end portion 35.

  In the present endoscope system 100, in addition to the basic configuration of the endoscope described above, the space from the endoscope distal end portion 35 to the endoscope insertion portion 19, the main body operation portion 17, and the connector 23 through the universal cord 21. Further, an optical fiber 41 for detecting strain in the section of the endoscope insertion portion 19 is inserted. The optical fiber 41 has the following configuration.

  FIG. 2 is a schematic view of the vicinity of the distal end portion 35 of the endoscope insertion portion 19, and FIG. 3 is a cross-sectional view taken along the line AA of FIG. Optical fibers 41A and 41B formed with a plurality of fiber Bragg gratings FBG1, FBG2,... Having different diffraction grating periods are inserted into the endoscope insertion portion 19. The fiber Bragg gratings FBG1, FBG2,... Are arranged at the same position in the section of the endoscope insertion portion 19 with respect to the longitudinal direction of each of the optical fibers 41A, 41B, and perform strain detection at each arrangement position. Functions as a strain sensor. That is, the position of the FBG1 of the optical fiber 41A and the position of the FBG1 of the optical fiber 42A are arranged at the same position in the longitudinal direction, and the distortion at the same position is detected.

  These optical fibers 41A and 41B are arranged on the outer peripheral side orthogonal to each other with respect to the center of the endoscope insertion portion 19, and based on the detected strain amount information, The shape displaced in the left-right direction can be detected.

First, the configuration of an optical fiber having a fiber Bragg grating and the principle of strain measurement will be described.
4A is a cross-sectional view of an optical fiber, FIG. 4B is a schematic diagram of a diffraction grating pair formed by overlapping two fiber Bragg gratings, and FIG. 5 is a fiber Bragg grating formed in an optical fiber. It is typical structure explanatory drawing of these.

  The optical fibers 41A and 41B are formed by a clad 43, an elliptical core 45, and an outer skin (not shown). In the section of the endoscope insertion portion 19, a fiber composed of a Bragg diffraction grating pair having a periodic refractive index structure. A Bragg grating (hereinafter abbreviated as FBG) is formed in the core 45.

  Each FBG1, FBG2,... Has a diffraction grating pair in which a first fiber Bragg grating FBGa and a second fiber Bragg grating FBGb having different diffraction grating periods are overlapped with each other, and FBG1a, FBG1b, FBG2a,. FBG2b,... Further, since the core 45 is elliptical, it has a birefringence difference in the orthogonal biaxial direction (XY direction) in a plane perpendicular to the fiber axis direction.

  The FBG has a refractive index modulation structure in which the refractive index is changed at a specific period δ in the core 45 of the optical fiber 41 as disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-258190. When light enters the optical fiber 41, light having a Bragg wavelength (λ = 2nδ) defined by the specific period δ and the average refractive index n of the core 45 is returned to the incident side as diffracted return light. Become. The FBG is formed in a size of about 5 to 20 mm, preferably about 10 mm in the axial direction of the core 45 with respect to the clad 43 having a diameter of about 0.1 mm, and is arranged at predetermined regular intervals in the axial direction of the core 45. Has been.

FIG. 6 is a graph showing the spectral intensities of the first to fourth diffracted return lights diffracted by the two fiber Bragg gratings FBGa and FBGb. As shown in FIGS. 5 and 6, each FBG in this configuration example has a refractive index modulation structure including a diffraction grating pair of first and second fiber Bragg gratings FBGa and FBGb that change at different periods δ _a and δ _b. And has a birefringence difference in an orthogonal biaxial direction (XY direction) in a plane perpendicular to the fiber axis direction. Therefore, when light is introduced from one end side of the optical fiber 41, when there is an incident light component having a wavelength corresponding to the diffraction grating period of the FBG, the periods δ _a , of the first and second fiber Bragg gratings FBG _a , FBG _b Bragg wavelengths (λ _ap = 2n ₁ δ _a , λaq = 2n ₂ δ _a , λ _bp = 2n) defined by δ _b and average refractive indexes n ₁ and n ₂ in the biaxial direction (XY direction) of the core 45 ₁ δ _b , λ _bq = 2n ₂ δ _b ) selectively generates diffracted light by the diffraction grating pair and returns to the light introduction side of the optical fiber 41 as diffracted return light. Then, FBGa in the optical fiber 41, when distortion occurs in _FBGb, FBG a, grating period [delta] _a of FBG _b, since [delta] _b is changed, thereby the wavelength of the diffracted return light is changed.

  FIGS. 7A, 7B, and 7C are graphs showing a state in which the wavelength width of the diffracted return light from the fiber Bragg grating changes due to strain in a direction orthogonal to the axial direction of the optical fiber, FIG. ), (B), and (C) are graphs showing states in which the wavelength of the diffracted return light from the fiber Bragg grating transitions due to axial strain of the optical fiber. Here, for easy understanding, one diffraction grating FBGa of the diffraction grating pair (FBGa, FBGb) will be described, but the same applies to the other diffraction grating FBGb.

  When strain in the direction orthogonal to the axial direction occurs in the FBGa, as shown in FIGS. 7A, 7B, and 7C, the peak wavelength of the diffracted return light from the FBGa is the strain generated in the FBGa. Transition according to size. For example, when compression occurs in the Y direction, the refractive index in the Y direction increases and expands in the X direction to decrease the refractive index in the X direction. As a result, the peak wavelengths transition in opposite directions. That is, it increases / decreases from the peak wavelength width W1 of the diffracted return light in the undistorted state. The amount of wavelength width transition from the peak wavelength width W1 of the diffracted return light at this time corresponds to the amount of strain in the direction orthogonal to the axial direction generated in the optical fiber 41 at the FBGa arrangement position.

  Further, when axial strain occurs in FBGa, as shown in FIGS. 8A, 8B, and 8C, the peak wavelength of the diffracted return light from FBGa is the axial strain generated in FBGa. Transition is made in response, and the transition is made in parallel while maintaining the interval between the peak wavelengths of the diffracted return light in the unstrained state. The amount of wavelength transition from the peak wavelength of the diffracted return light at this time corresponds to the amount of axial strain generated in the optical fiber 41 at the FBGa arrangement position.

  In addition, a plurality of FBGs (FBG1, FBG2,...) Having different peak wavelengths of the diffracted return light are arranged at different positions in the optical fiber 41, but the diffracted return light from each FBG is within the optical fiber 41. Since the optical path lengths from the light introduction side are different, the distortion generated at each position of each FBG can be detected individually by selectively taking out according to the time difference until reaching the light detection unit (details will be described later) .

  In this manner, the diffracted return light from each FBG of the optical fiber 41 is individually detected, and the peak wavelength width transition amount and the wavelength transition amount of each diffracted return light are obtained, so that each FBG on the optical fiber 41 is obtained. Distortion at the arrangement position (distortion in the direction orthogonal to the axial direction and axial distortion) is detected. Since each FBG can detect the axial direction and the distortion in the biaxial direction orthogonal to the axial direction, it is possible to detect the shape of the endoscope insertion portion 19 at the position where the FBG is arranged, that is, the curved state.

  In addition, 400 nm-2200 nm can use the wavelength of the emitted light from the light source part 49 suitably.

Next, an outline of a procedure for detecting the shape of the endoscope insertion portion 19 will be described.
FIG. 9 is a flowchart for estimating the shape of the endoscope insertion portion by irradiating each diffraction grating pair with light of a predetermined wavelength. In step S1, FBG _ia (i = 1, 2, 3,...) Wavelengths λ _api and λ _aqi corresponding to the X direction strain and the Y direction strain are set, and pulses having a sweep waveform of λ _api are sequentially introduced into the optical fiber 41 in step S2, and the diffraction return light wavelength is measured. Similarly, in step S3, pulses having a sweep waveform of λ _aqi are sequentially introduced into the optical fiber 41, and the diffraction return light wavelength is measured.

Similarly, the wavelengths λ _bpi and λ _bqi corresponding to the X-direction distortion and Y-direction distortion of FBG _ib (i = 1, 2, 3,...) _Are set in step S4, and λ _bpi is swept in step S5. Waveform pulses are sequentially introduced into the optical fiber 41 to measure the diffraction return light wavelength. In step S6, pulses having a sweep waveform of λ _bqi are sequentially introduced into the optical fiber 41 to measure the diffraction return light wavelength.

Next, on the basis of the wavelength transition amounts of the wavelengths λ _api , λ _aqi , λ _bpi , λ _bqi measured in the above steps, in step S 7, the arithmetic processing unit performs distortion components ε _x , ε _y , ε at the FBG _i position. _z is calculated.

The calculation of the strain components ε _x , ε _y , ε _z
Δλ _{ax represents} the change from the undistorted state of the wavelength λ _api of the first diffracted return light, Δλ _{ay represents} the change from the undistorted state of the wavelength λ _aqi of the second diffracted return light, and the third diffracted return light. wavelength lambda _bpi variation of [Delta] [lambda] _bx from unstrained state of the _fourth diffraction return light having a wavelength of lambda variation of [Delta] [lambda] _by from unstrained state of the _BQI, [Delta] T the change in environmental temperature, x-direction, y When the strain change amount in the direction and z direction is Δε _x , Δε _y , Δε _z , and the matrix coefficient is K _ij , it can be obtained from the following equation described in US Pat. No. 5,591,965.

According to the above formula, in addition to Δε _x , Δε _y , Δε _z , the environmental temperature change ΔT is also obtained at the same time, but the temperature of the endoscope insertion portion 19 inserted into the body cavity is substantially constant at the body temperature. Therefore, it is not a particularly important item in this configuration example.

In step S8, it is determined whether or not the calculation of the strain change amounts Δε _x , Δε _y , Δε _z of the final FBGs of FBG1, FBG2,... Arranged along the axial direction of the optical fiber 41 is completed. If it is discriminated and it is not the final FBG, it is incremented in step S9 and the process returns to step S1 to continue the measurement.

If it is determined that the calculation for the final FBG has been completed, it is determined in step S10 whether or not the detection of all the optical fibers (two optical fibers 41A and 41B in the present configuration example) has been completed. If there is an optical fiber, the process returns to step S1, and the measurement of the undetected optical fiber is continued. Then, in step S11, the shape of the endoscope insertion portion 19 is estimated from the obtained strain change amounts Δε _x , Δε _y , Δε _z of all the FBGs of the respective optical fibers. The shape estimation procedure will be described in detail later.

  Next, a configuration example and operation of a specific measurement optical system for detecting the shape of the endoscope insertion portion 19 will be described. FIG. 10 is a block diagram showing a measurement optical system using a shape detection unit and an optical fiber. The optical fiber 41A inserted through the endoscope insertion section 19 (see FIG. 1) is connected to the optical unit 47A of the shape detection section 10 in the control device 13 (see FIG. 1). The optical unit 47A introduces light emitted from the light source unit 49 into the optical fiber 41A, detects diffracted return light from each of the FBG1, FBG2,..., And outputs a detection signal OUT of the diffracted return light to the control unit 51. Output. Similarly, the optical fiber 41 </ b> B is connected to the optical unit 47 </ b> B of the shape detection unit 10, and the diffraction return light detection signal OUT is input to the control unit 51.

The optical fibers 41A and 41B and the optical units 47A and 47B have the same configuration. Here, in order to simplify the description, the optical fiber 41A and the optical unit 47A will be described as an example. In the optical fiber 41A, FBG1, FBG2, FBG3,... Are arranged at different predetermined distances from the light introduction end 53 of the optical fiber 41A. Each of the FBG1, FBG2, FBG3,... Has a different diffraction grating period, and the wavelengths of the diffracted return light generated are different wavelengths λ ₁ , λ ₂ , λ ₃ ,.

More specifically, each FBG1, FBG2, FBG3,... Is composed of two FBGs (FBGa and FBGb), and has different refractive indexes in the XY directions. wavelength of the diffracted return light from, lambda _ap1, next lambda _aq1, the wavelength of the diffracted return light from FBGb (hereinafter also referred to as FBG1b) of FBG1 is, lambda _bp1, the lambda _BQ1. Similarly, the wavelengths of the diffracted return light from the _{FBG 2} are λ _ap2 , λ _aq2 , λ _bp2 , and λ _bq2 .

  On the other hand, the optical unit 47A of the shape detection unit 10 to which the optical fiber 41A is connected is provided with a beam splitter 55 that functions as an optical path separation unit in the middle of the optical path connecting the light source unit 49 and the optical fiber 41A. An optical shutter 57 is disposed in the middle of the optical path, and a light detection unit 59 is disposed in front of the optical path of the optical shutter 57.

  Further, the light source unit 49 receives the light source control signal RO from the control unit 51, and receives FBG1 (FBG1a, FBG1b), FBG2 (FBG2a, FBG2b), FBG3 (FBG3a, FBG3b) via the optical unit 47A. ,... Are emitted in a time-series manner. As the light source unit 49, for example, a known light source such as a laser light source capable of wavelength sweeping or a light source that selectively emits only a specific wavelength component by connecting an optical filter such as a bandpass filter to a white light source can be used.

  The optical shutter 57 of the optical unit 47A is an electro-optical shutter formed of an optical functional material having an electro-optical effect capable of high-speed light modulation. As the optical functional material, for example, PLZT (lead lanthanum zirconate titanate) In addition, KDP (potassium dihydrogen phosphate) crystal, which is a nonlinear optical crystal, can be used. FIG. 11 shows a configuration example of the optical shutter 57. The optical functional material 61 having the electro-optic effect is combined with the polarizing plates 65 and 67 arranged in crossed Nicols by utilizing the fact that the orientation direction of the crystal is changed by the driving voltage from the driving circuit 63, thereby transmitting / shielding light. Can be controlled at high speed on the order of nsec.

  The light transmitted through the optical shutter 57 is detected at the timing when the control signal of the control unit 51 is received by the light detection unit 59 shown in FIG. 10 using a photoelectric effect such as a photodiode, a phototransistor, or a photoelectric tube.

  That is, the diffracted return light returning from FBG1a, FBG1b, FBG2a, FBG2b, FBG3a, FBG3b,... Is extracted from the incident light path from the light source unit 49 by the beam splitter 55 of the optical unit 47A, and is transmitted through the optical shutter 57. It is detected by the detection unit 59.

  Next, an optical fiber strain detection procedure by the optical fiber 41A and the shape detection unit 10 will be described. Here, each optical path length from the light incident end of the optical fiber 41A to the light source unit 49, the beam splitter 55, the optical shutter 57, and the light detection unit 59 will be omitted.

First, the control unit 51 outputs a light source control signal RO to the light source unit 49 to sequentially emit a plurality of narrowband wavelength pulse lights from the light source unit 49. As shown in FIG. 12, the pulsed light has a wavelength (center narrowband wavelength) λ _i corresponding to a diffraction grating period in a non-distorted state of a specific FBG (for example, FBG1a) around the wavelength. , A total of five types of pulsed light of different wavelengths (near-band narrowband wavelengths) λ _i−2Δ , λ _i−Δ , λ _{i + Δ} , λ _{i + 2Δ} , which correspond to one FBG Are sequentially emitted from the light source unit 49. The plurality of pulse lights are pulse lights for detecting the wavelength transition amount corresponding to the strain state of the FBG shown in FIG. 7 and FIG. 8, and any one of the pulse lights that the FBG generates the diffraction return light. The strain state of the FBG is detected from the wavelength.

FBG 1 (e.g., FBG1a) relative to the center of the narrow band wavelength is lambda _1, sequentially wavelength lambda _1-2Deruta before and after the _{wavelength, λ 1-Δ, λ 1} + Δ, the pulse light of lambda _{1 + 2.DELTA.} From the light source unit 49 Exit. Each emitted pulsed light passes through the beam splitter 55 of the optical unit 47A, is irradiated onto the light incident end of the optical fiber 41A, and is sequentially introduced into the optical fiber 41A as incident light.

Here, a control time chart by the control unit is shown in FIG. First, using the light source control signal RO from the control unit 51 as a trigger, the light source unit 49 introduces pulsed light having a wavelength of _λ1-2Δ into the optical fiber 41A. Then, in the optical fiber 41A, the pulsed light having the wavelength _λ1-2Δ reaches the FBG 1a at the time ta, and the diffracted return light P1 generated here returns to the incident end of the optical fiber 41A at the same time ta. The returned diffracted return light P2 is guided to the optical shutter 57 by the beam splitter 55 shown in FIG.

  Then, the control unit 51 outputs the light source control signal RO, and after the RO becomes active, the pulse light one-way transit time ta from the pulsed light introduction side of the optical fiber 41A to the FBG1 (FBG1a) is doubled. After a delay time corresponding to the round trip time, a shutter control signal OC for opening the optical shutter 57 is output to the optical shutter 57. Thereby, when the diffracted return light P2 returns, the optical shutter 57 is in the light-transmitting state from the light-shielding state at that timing, and the light detection unit 59 is irradiated with the diffracted return light P2. .

  Then, the light detection unit 59 performs control for accumulating signal charges in the Lo period of the reset control signal RS output from the control unit 51 and performing charge reset in the Hi period, and is irradiated during the Lo period of the reset control signal RS. The signal charge of the light diffracted light P2 is selectively detected.

When the detection with respect to the pulsed light with the wavelength _λ1-2Δ is completed, the detection with respect to the pulsed light with the wavelength λ1 _-Δ is subsequently performed. The pulsed light of wavelength λ _1-Δ is emitted from the light source unit 49 in synchronization with the light source control signal RO from the control unit 51, and is detected by the light detection unit 59 in synchronization with the shutter control signal OC. In this way, each pulse light is sequentially introduced into the optical fiber 41A at intervals of the period tp, and the detection of the diffracted return light by the light detection unit 59 is repeatedly performed.

In the example shown in FIG. 13, pulsed light beams having wavelengths λ _1-2Δ , λ _1-Δ , λ ₁ , λ _{1 + Δ} , and λ _{1 + 2Δ} are sequentially introduced into the optical fiber 41A at a period tp, and light detection is performed at each period tp. When the detection is performed by the unit 59, only the second pulsed light having the wavelength λ _1-Δ is shown in which the diffracted return light P3 is generated from the FBG ₁ (FBG 1a). Since the position of the FBG 1 in the optical fiber 41A does not change, the time for the diffracted return light with respect to each pulse light to reach the optical shutter 57 and the light detection unit 59 is the same. In the illustrated example, when the wavelength of the pulsed light is other than λ _1−Δ , the pulsed light passes through the FBG 1 without being diffracted by the FBG 1, so that the diffracted return light does not return to the beam splitter 55. Only when the wavelength of the pulsed light is λ _1-Δ , the signal charge of the diffracted return light is detected after a time of 2 ta from the emission. In the above case, it can be seen that the diffraction grating period of the FBG 1 is 1 / λ _1−Δ , and distortion that is shifted from the reference diffraction grating period 1 / λ ₁ by the period 1 / (− Δ) has occurred.

  Next, similarly to the detection of the strain state of the FBG 1a described above, pulse light having different wavelengths corresponding to the diffraction grating period of the FBG 1b is sequentially introduced into the optical fiber 41A for the FBG 1b, and the diffracted return light is detected. , FBG1b distortion state is detected. Thereby, the distortion state of FBG1 is detected.

  Further, similarly to the detection of the strain state of the FBG 1 described above, pulse lights having different wavelengths are sequentially introduced into the optical fiber 41A for FBG 2 (FBG 2a, FBG 2b), FBG 3 (FBG 3a, FBG 3b),. Each diffracted return light is detected. According to this procedure, the respective strain states can be detected from the FBG1, FBG2, FBG3,... Of the optical fiber 41A, and the strain distribution in the longitudinal direction of the optical fiber 41 is obtained. In the above example, pulse light of five types of wavelengths is used for one FBG. However, by using pulse light of various wavelengths, the strain measurement range can be expanded and the detection accuracy can be improved.

  Similarly, the strain distribution of each optical fiber 41B can be obtained for the optical fiber 41B by detecting the diffracted return light by the optical unit 47B.

The shape of the endoscope insertion portion 19 can be estimated from the strain change amounts Δε _x , Δε _y , Δε _{z in} the x direction, the y direction, and the z direction of each part of the optical fibers 41A, 41B obtained as described above. It becomes. FIG. 14 is a cross-sectional view for explaining the bending direction of the endoscope insertion portion, and FIG. 15 is a table showing the relationship between the detected strain and the bending direction of the endoscope insertion portion.

For example, at a certain FBG arrangement position, the strain change amount Δε _{ya in} the y direction of the optical fiber 41A is smaller than the strain change amount Δε _{yb in} the y direction of the optical fiber 41B, and the strain change amount Δε _{za in} the z direction of the optical fiber 41A. Is smaller than the strain variation Δε _{zb in} the z direction of the optical fiber 41B, it can be seen that the endoscope insertion portion 19 is bent upward (U) at this FBG position. That is, when the endoscope insertion portion 19 bends upward (U), the strain (compression) in the y direction is greater in the optical fiber 41A than in the optical fiber 41B, and the strain (elongation) in the z direction is greater in the optical fiber 41B. Becomes larger than the optical fiber 41A. The larger the distortion value, the larger the curvature of the curve.

  The other bending directions (D, L, R) can be similarly estimated. In addition, by arranging the optical fibers 41A and 41B on the outer peripheral side in the diameter direction of the endoscope insertion portion 19, the distortion of the optical fibers 41A and 41B due to the deformation of the endoscope insertion portion 19 is increased, and the strain detection accuracy is increased. Will improve.

In this configuration example, strain change amounts Δε _x , Δε _y , and Δε _z in the x direction, the y direction, and the z direction can be detected at two positions on the outer peripheral side orthogonal to the center of the endoscope insertion portion 19, respectively. Since the optical fibers 41A and 41B are arranged, the deformed shape of the endoscope insertion portion 19 is traced by the pair of optical fibers 41A and 41B, as shown in FIG. 16 as an example of the bending state of the endoscope insertion portion. it can.

  The obtained shape of the endoscope insertion portion 19 is output to the display portion 15 shown in FIG. 1 and the like, and the operator of the endoscope 11 is notified of the shape of the endoscope insertion portion 19. As a result, the operator of the endoscope 11 can grasp the three-dimensional shape of the endoscope insertion portion 19 being operated and inserted into the body cavity, and can specify the inspection target region or the endoscope insertion portion 19. The advance / retreat operation can be performed smoothly.

  The optical system of the shape detection unit 10 is not limited to the above example, and can be changed as appropriate. For example, as shown in FIG. 17, the diffraction return lights from the two optical fibers 41 and 41B may be extracted by the beam splitter 55, and then the optical paths may be merged by the half mirror 75 and input to the optical shutter 57. . In this case, only one system of the optical shutter 57 and the light detection unit 59 is required, and the configuration can be simplified and the control can be easily performed. In this case, it is necessary to set the diffraction grating periods of the FBGs of the two optical fibers 41 and 41B to different periods so that the diffraction return lights of the optical fibers 41 and 41B can be discriminated.

Next, another configuration example of the endoscope shape detection apparatus will be described.
In the endoscope system 100 described above, the optical fibers 41A and 41B connected to the shape detection unit 10 are provided in the endoscope insertion unit 19, but here, as shown in FIG. The treatment tool 79 is inserted into a forceps hole 77 communicating along the longitudinal direction of the insertion portion 19.

  A forceps hole 77 is formed in the endoscope insertion portion 19 from the forceps insertion portion 39 to the endoscope distal end portion 35 shown in FIG. 1, and a long treatment tool 79 is inserted into the forceps hole 77 so as to be freely inserted and removed. Is done. Then, as shown in FIG. 19, the BB cross section of the treatment instrument 79, optical fibers 41 A and 41 B similar to those described above are arranged in a direction orthogonal to each other on the outer peripheral side of the treatment instrument 79.

  As shown in FIGS. 10 and 17, the optical fibers 41A and 41B are connected to the shape detectors 10 and 10A, respectively, so that the distortion of each FBG is detected. According to this configuration, it is possible to detect deformation of the endoscope insertion portion 19 by simply inserting the treatment instrument 79 without changing the design of the endoscope insertion portion 19.

  Also, as shown in FIG. 20, the optical fibers 41A and 41B have an elliptical core, and give a birefringence difference in the orthogonal biaxial direction (XY direction) in a plane perpendicular to the fiber axis direction. In addition to the optical fiber (see FIG. 4), a so-called panda fiber can also be used. The panda fibers 41 </ b> C and 41 </ b> D are configured by disposing stress applying portions 87 on the clad 83 on both sides of the core 85, and applying an X-direction tensile stress and a Y-direction compressive stress to the core 85 by the stress generated in the stress applying portion 87. The birefringence difference in the XY direction is induced by the photoelastic effect.

  Such panda fibers 41C and 41D are formed by inserting a glass having a thermal expansion coefficient larger than that of the clad 83 into a hole formed in the clad 83 by an ultrasonic drill to form a drawing base material, and in the cooling process of the fiber after the drawing, A stress is applied to the core 85 because tensile strain is generated in the stress applying portion 87 having a larger thermal expansion coefficient than that of 83.

  According to the endoscope shape detection device described above, distortion of the endoscope insertion portion can be detected by a simple optical system, and shape detection can be performed at low cost and with high accuracy. For example, when detecting the diffracted return light returning from the FBG in the optical fiber, OFDR (which specifies the position of the FBG from light intensity conversion by interference between the diffracted return light from the FGB and the reflected light from the reference reflecting surface) Optical Frequency Domain Reflectometry) can also be used, but this method requires an expensive optical spectrum analyzer and complicates the apparatus. On the other hand, according to the endoscope shape detection apparatus of this configuration, since the diffraction return light from each FBG is selectively extracted by an optical shutter that can be driven at high speed, it is inexpensive without performing spectral characteristic measurement. The distortion generated in the optical fiber can be detected with a configuration suitable for miniaturization. Furthermore, since the amount of strain at the position where each FBG in the optical fiber is arranged is reliably detected, the shape of the endoscope insertion portion 19 can be accurately detected by a simple procedure.

  In addition, the optical fiber inserted through the endoscope insertion portion 19 is not limited to two configurations arranged in a direction orthogonal to the center on the cross section, and a larger number of optical fibers may be arranged. In that case, the shape detection accuracy of the endoscope insertion portion 19 can be further improved.

  Further, the positions of the FBGs in the optical fiber may be arranged closer to the distal end of the endoscope in addition to being arranged at equal intervals in the region of the endoscope insertion portion 19. By reducing the FBG arrangement interval at the endoscope distal end, the accuracy of deformation detection is increased, and the state of the endoscope distal end 35 that is particularly important for shape detection can be accurately grasped.

  When strain is detected by diffracted return light from the FBG, the endoscope insertion portion 19 is inserted into the body cavity and maintained at a temperature near the body temperature via the mucous membrane in the body cavity, and the influence of the change in the environmental temperature The temperature error of the strain detection value can be kept small.

  As described above, the present invention is not limited to the above-described embodiments, and modifications and applications by those skilled in the art based on the description of the specification and well-known techniques are also within the scope of the present invention. It is included in the range to calculate.

As described above, the following items are disclosed in this specification.
(1) At least two optical fibers each having a diffraction grating are arranged at different positions along the longitudinal direction of the endoscope insertion portion, and distortions generated in the respective optical fibers due to deformation of the endoscope insertion portion. An endoscope shape detection device that detects the shape of the endoscope insertion portion by obtaining from the diffracted light of the diffraction grating,
Each optical fiber is discretely arranged at a plurality of positions along a fiber axis, each of which includes a pair of diffraction gratings formed by overlapping a first fiber Bragg grating and a second fiber Bragg grating having mutually different diffraction grating periods, It has a birefringence difference in the biaxial direction perpendicular to the fiber axis direction,
A light source unit for introducing incident light including a wavelength corresponding to each diffraction grating period of the diffraction grating pair into the optical fiber;
An optical path separating unit that extracts the diffracted return light that is diffracted and returned by the diffraction grating pair from the incident light introduced into each of the optical fibers; and
A light detection unit for detecting diffraction return light of each of the optical fibers taken out from the optical path separation unit;
An optical shutter disposed in the middle of the optical path between the optical path separator and the light detector;
An optical shutter driving unit that opens and closes the optical shutter and selectively detects the diffracted return light from the specific fiber Bragg grating by the light detection unit;
The first fiber Bragg grating causes the first fiber Bragg grating to diffract the first diffraction return light and the second diffraction return light that are diffracted at mutually different wavelengths according to the birefringence difference, and the incident light is caused to the second fiber Bragg grating. The orthogonal biaxial directions acting on each diffraction grating pair based on each wavelength information including third diffraction return light and fourth diffraction return light diffracted at different wavelengths according to the birefringence difference The amount of strain in the fiber axis direction is obtained for each optical fiber, and the shape of the endoscope insertion portion is detected from the relationship between the position of the diffraction grating pair of each optical fiber and the amount of strain in each direction. An arithmetic processing unit to perform,
An endoscope shape detection apparatus comprising:
According to this endoscope shape detection apparatus, incident light of a plurality of types of wavelengths is sequentially introduced into an optical fiber, and diffracted return light returning from the fiber Bragg grating is detected at a predetermined timing via an optical shutter. From the difference in detection timing, it is possible to individually detect the amount of strain while identifying each of the plurality of fiber Bragg gratings. In other words, the strain generated in the optical fiber is detected with a configuration that is inexpensive and suitable for downsizing without performing spectroscopic analysis with a spectroscope, and the amount of strain at the position where the fiber Bragg grating of each optical fiber is arranged is reliably determined. The shape of the endoscope insertion portion can be accurately detected by a simple procedure.

(2) The endoscope shape detection device according to (1),
The light source unit is different from each other in a plurality of types of narrow-band wavelength pulse lights having a center diffraction wavelength corresponding to a reference diffraction grating period in an unstrained state of the fiber Bragg grating and other wavelengths around the center diffraction wavelength. Sequentially introduced into the optical fiber at the timing,
The optical shutter drive unit performs open / close drive to open the optical shutter unit in accordance with the timing of introducing the pulsed light into the optical fiber by the light source unit,
The light detection unit selectively detects the diffracted return light in synchronization with the optical shutter drive timing of the optical shutter drive unit;
An endoscope shape detection apparatus in which the arithmetic processing unit obtains a distortion amount acting on the diffraction grating pair from a difference between the wavelength of the pulsed light corresponding to the detected diffracted return light and the central diffraction wavelength.
According to this endoscope shape detection apparatus, a plurality of types of pulsed light having a central narrowband wavelength and other close narrowband wavelengths are sequentially introduced into an optical fiber, and optical shutters are respectively synchronized with the returning diffracted return light. Diffracted return light is detected, so that the diffracted return light can be detected at any one of the multiple detections, and acts on the diffraction grating pair from the difference between the narrowband wavelength corresponding to that time and the center narrowband wavelength. The amount of distortion to be obtained can be obtained.

(3) The endoscope shape detecting device according to (1) or (2),
After the shutter drive unit emits light from the light source unit, the emitted light reaches one of the fiber Bragg gratings for which the amount of distortion is to be detected, and diffracted return light from the fiber Bragg grating An endoscope shape detection device that changes the optical shutter from a closed state to an open state in accordance with an elapsed time until it reaches the optical shutter.
According to this endoscope shape detection device, by opening the optical shutter in accordance with the return timing of the diffracted return light from the fiber Bragg grating, while identifying each of the plurality of fiber Bragg gratings arranged at different positions, Diffracted return light can be selectively extracted.

(4) The endoscope shape detection device according to any one of (1) to (3),
Δλ _ax , the change from the undistorted state of the wavelength of the first diffracted return light,
Δλ _ay , a change from the undistorted state of the wavelength of the second diffracted return light,
Δλ _bx , the change from the undistorted state of the wavelength of the third diffracted return light,
The change from the undistorted state of the wavelength of the fourth diffracted return light is expressed as Δλ _by ,
ΔT is the change in environmental temperature
The strain variation in the x direction, the y direction, which are the orthogonal biaxial directions, and the z direction, which is the fiber axis direction, is expressed as Δε _x , Δε _y , Δε _z ,
When the matrix coefficient is K _ij ,
An endoscope shape detection apparatus in which the arithmetic processing unit obtains the distortion amount from the following equation.

  According to this endoscope shape detection apparatus, the fiber Bragg grating is arranged from the change in the wavelength of the total of four diffracted return lights, two each returning from each of the two fiber Bragg gratings arranged at the same position. The amount of distortion at the selected position can be obtained.

(5) The endoscope shape detection device according to any one of (1) to (4),
An endoscope shape detection apparatus, wherein the optical shutter is an electro-optical shutter configured to include an optical functional material having an electro-optical effect.
According to this endoscope shape detection apparatus, each fiber Bragg grating in the optical fiber can be detected with high resolution by using an electro-optical shutter that can be driven at a high speed on the order of nsec, and the detection accuracy of the strain distribution can be improved.

(6) The endoscope shape detection device according to any one of (1) to (4),
An endoscope shape detection apparatus in which the optical path branching unit, the optical shutter, and the light detection unit are individually provided for each optical fiber.
According to this endoscope shape detection apparatus, since each optical fiber is provided with a measurement optical system, strain detection of each optical fiber can be performed simultaneously, and the measurement time for shape detection can be shortened.

(7) The endoscope shape detection device according to any one of (1) to (5),
An endoscope shape detection apparatus in which the optical shutter and the light detection unit are provided in common before the optical path branching portion branched from the optical fibers is joined.
According to this endoscope shape detection apparatus, only one system of the optical shutter and the light detection unit is required, the configuration can be simplified, and the control is also simplified.

(8) The endoscope shape detection device according to any one of (1) to (7),
An endoscope shape detection device in which the optical fibers are arranged on the outer peripheral sides of the endoscope insertion portion in the diameter direction perpendicular to each other.
According to this endoscope shape detection apparatus, since the detection is performed at the outer peripheral position where distortion due to deformation of the endoscope insertion portion is greatly generated, the shape can be detected with high accuracy.

(9) The endoscope shape detection device according to any one of (1) to (8),
An endoscope shape detection apparatus in which the arrangement density of the diffraction grating pairs is made uniform over the entire length of the endoscope insertion portion.
According to this endoscope shape detection apparatus, the amount of distortion can be detected evenly over the entire length of the endoscope insertion portion.

(10) The endoscope shape detection device according to any one of (1) to (8),
An endoscope shape detection apparatus in which an arrangement density of the diffraction grating pairs is increased toward an insertion side of the endoscope insertion portion into a body cavity.
According to this endoscope shape detection apparatus, it is possible to accurately detect the amount of distortion on the insertion side of the endoscope insertion portion into the body cavity.

(11) The endoscope shape detection device according to any one of (1) to (10),
The endoscope insertion portion is provided with a forceps hole that communicates along the longitudinal direction of the endoscope insertion portion, and includes a long treatment tool inserted into the forceps hole,
An endoscope shape detection device in which the optical fibers are arranged at different positions on the outer peripheral side in the diameter direction of the treatment instrument.
According to this endoscope shape detection device, the shape of the endoscope insertion portion can be detected without changing the configuration of the endoscope by providing the treatment instrument with an optical fiber.

(12) An endoscope system that acquires captured image information of a subject from imaging means provided on the distal end side of an endoscope insertion portion,
The endoscope shape detection device according to any one of (1) to (11);
A display unit for displaying the detection information of the shape of the endoscope insertion unit and the captured image information;
Endoscope system equipped with.
According to this endoscope system, the result of detecting the shape of the endoscope insertion portion and the captured image of the subject are displayed on the display portion, thereby inserting the endoscope during operation inserted into the body cavity. The shape of the part can be grasped, and the part to be examined can be specified and the endoscope insertion part can be smoothly advanced and retracted.

10 Shape Detection Unit (Endoscope Shape Detection Device)
DESCRIPTION OF SYMBOLS 11 Endoscope 13 Control apparatus 15 Display part 19 Endoscope insertion part 35 Endoscope tip part 41, 41A, 41B Optical fiber 49 Light source part 51 Control part (arithmetic processing part)
55 Beam splitter (optical path separator)
57 Optical shutter (optical shutter, electro-optical shutter)
59 Photodetector 63 Drive circuit (Optical shutter driver)
77 Forceps hole 79 Treatment tool 100 Endoscope system FBG Fiber Bragg grating δa, δb Grating period

Claims (12)

At least two optical fibers each having a diffraction grating are arranged at different positions along the longitudinal direction of the endoscope insertion portion, and distortion generated in each optical fiber due to deformation of the endoscope insertion portion is the diffraction grating. An endoscope shape detecting device for detecting the shape of the endoscope insertion portion by obtaining from the diffracted light of
Each optical fiber is discretely arranged at a plurality of positions along a fiber axis, each of which includes a pair of diffraction gratings formed by overlapping a first fiber Bragg grating and a second fiber Bragg grating having mutually different diffraction grating periods, It has a birefringence difference in the biaxial direction perpendicular to the fiber axis direction,
A light source unit for introducing incident light including a wavelength corresponding to each diffraction grating period of the diffraction grating pair into the optical fiber;
An optical path separating unit that extracts the diffracted return light that is diffracted and returned by the diffraction grating pair from the incident light introduced into each of the optical fibers; and
A light detection unit for detecting diffraction return light of each of the optical fibers taken out from the optical path separation unit;
An optical shutter disposed in the middle of the optical path between the optical path separator and the light detector;
An optical shutter driving unit that opens and closes the optical shutter and selectively detects the diffracted return light from the specific fiber Bragg grating by the light detection unit;
The first fiber Bragg grating causes the first fiber Bragg grating to diffract the first diffraction return light and the second diffraction return light that are diffracted at different wavelengths according to the birefringence difference, and the incident light is caused to the second fiber Bragg grating. The orthogonal biaxial directions acting on each diffraction grating pair based on each wavelength information including third diffraction return light and fourth diffraction return light diffracted at different wavelengths according to the birefringence difference The amount of strain in the fiber axis direction is obtained for each optical fiber, and the shape of the endoscope insertion portion is detected from the relationship between the position of the diffraction grating pair of each optical fiber and the amount of strain in each direction. An arithmetic processing unit to perform,
An endoscope shape detection apparatus comprising: The endoscope shape detecting device according to claim 1,
The light source unit is different from each other in a plurality of types of narrow-band wavelength pulse lights having a center diffraction wavelength corresponding to a reference diffraction grating period in an unstrained state of the fiber Bragg grating and other wavelengths around the center diffraction wavelength. Sequentially introduced into the optical fiber at the timing,
The optical shutter drive unit performs open / close drive to open the optical shutter unit in accordance with the timing of introducing the pulsed light into the optical fiber by the light source unit,
The light detection unit selectively detects the diffracted return light in synchronization with the optical shutter drive timing of the optical shutter drive unit;
An endoscope shape detection apparatus in which the arithmetic processing unit obtains a distortion amount acting on the diffraction grating pair from a difference between the wavelength of the pulsed light corresponding to the detected diffracted return light and the central diffraction wavelength. The endoscope shape detection device according to claim 1 or 2,
After the shutter drive unit emits light from the light source unit, the emitted light reaches one of the fiber Bragg gratings for which the amount of distortion is to be detected, and diffracted return light from the fiber Bragg grating An endoscope shape detection device that changes the optical shutter from a closed state to an open state in accordance with an elapsed time until it reaches the optical shutter. The endoscope shape detection device according to any one of claims 1 to 3,
Δλax is the change from the undistorted state of the wavelength of the first diffracted return light,
Δλ _ay , a change from the undistorted state of the wavelength of the second diffracted return light,
Δλ _bx , the change from the undistorted state of the wavelength of the third diffracted return light,
The change from the undistorted state of the wavelength of the fourth diffracted return light is expressed as Δλ _by ,
ΔT is the change in environmental temperature
The strain variation in the x direction, the y direction, which are the orthogonal biaxial directions, and the z direction, which is the fiber axis direction, is expressed as Δε _x , Δε _y , Δε _z ,
When the matrix coefficient is K _ij ,
An endoscope shape detection apparatus in which the arithmetic processing unit obtains the distortion amount from the following equation.

The endoscope shape detection device according to any one of claims 1 to 4,
An endoscope shape detection apparatus, wherein the optical shutter is an electro-optical shutter configured to include an optical functional material having an electro-optical effect. The endoscope shape detection device according to any one of claims 1 to 5,
An endoscope shape detection apparatus in which the optical path branching unit, the optical shutter, and the light detection unit are individually provided for each optical fiber. The endoscope shape detection device according to any one of claims 1 to 5,
An endoscope shape detection apparatus in which the optical shutter and the light detection unit are provided in common before the optical path branching portion branched from the optical fibers is joined. The endoscope shape detection device according to any one of claims 1 to 7,
An endoscope shape detection device in which the optical fibers are arranged on the outer peripheral sides of the endoscope insertion portion in the diameter direction perpendicular to each other. The endoscope shape detection device according to any one of claims 1 to 8,
An endoscope shape detection apparatus in which the arrangement density of the diffraction grating pairs is made uniform over the entire length of the endoscope insertion portion. The endoscope shape detection device according to any one of claims 1 to 8,
An endoscope shape detection apparatus in which an arrangement density of the diffraction grating pairs is increased toward an insertion side of the endoscope insertion portion into a body cavity. The endoscope shape detection device according to any one of claims 1 to 10,
The endoscope insertion portion is provided with a forceps hole that communicates along the longitudinal direction of the endoscope insertion portion, and includes a long treatment tool inserted into the forceps hole,
An endoscope shape detection device in which the optical fibers are arranged at different positions on the outer peripheral side in the diameter direction of the treatment instrument. An endoscope system for acquiring captured image information of a subject from imaging means provided on the distal end side of an endoscope insertion portion,
The endoscope shape detection device according to any one of claims 1 to 11,
A display unit for displaying the detection information of the shape of the endoscope insertion unit and the captured image information;
Endoscope system equipped with.

Images