Optical fiber probe system and medical system

Abstract

To provide an optical fiber probe system and the like that minimize an excitation volume in an object, have no bending addition loss, and are easily handled and are inexpensive.SOLUTION: There is provided an optical fiber probe system 100 that irradiates an object with a laser beam through an optical fiber to receive scattering light. The optical fiber probe system 100 comprises: a first optical fiber 10 transmitting from a light source a laser beam for irradiation; a hollow second optical fiber 20 irradiating from a tip end thereof an object with a laser beam through the first optical fiber to receive scattering light; a third optical fiber 30 transmitting to a detector the scattering light which the second optical fiber has received; an optical system 41 that has a first optical path 411 transmitting the laser beam from the first optical fiber to the second optical fiber and a second optical path 412 transmitting the scattering light from the second optical fiber to the third optical fiber; a coupler 40 storing the optical system; and a tubular outer cylindrical tube 50 connected to the coupler and storing the second optical fiber therein.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical fiber probe system and a medical system using the optical fiber probe system.

Background Art

[0002] Conventionally, an optical fiber has been used at the tip of an optical fiber probe to irradiate an object with light or radiation of a predetermined wavelength from a light source, receive scattered light from the object, and guide the received scattered light to a detector such as a spectroscope to analyze the scattered light, thereby detecting the characteristics of the object. A technique for this is known.

[0003] For example, Patent Document 1 discloses a hollow fiber probe that can significantly improve detection ability and spatial resolution and miniaturize the overall configuration. This hollow fiber probe detects light emitted from a sample, and includes a hollow fiber having a cylindrical hollow core and a micro lens with a large numerical aperture disposed on one end side of the hollow fiber, with the inner diameter of the core and the outer diameter of the micro lens being approximately equal and the micro lens being fitted into the core.

[0004] Also, Non-Patent Document 1 discloses an optical fiber probe that uses a plurality of solid-type optical fibers at the tip and integrates an optical filter and a lens at the tip thereof. This optical fiber probe realizes a small-diameter and high-efficiency Raman probe that can optimize the collection efficiency, minimize noise, and collect high-speed and high-quality data.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Documents

[0006]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the invention of Patent Document 1, since the hollow optical fiber has a large bending additional loss, the intensity of the spectrum of the acquired scattered light (for example, Raman scattered light in the case of Raman spectroscopy) varies, which becomes a significant noise factor in performing quantification and discrimination by multivariate analysis and machine learning.

[0008] Also, in the invention of Non-Patent Document 1, by using a solid-core optical fiber, the bending additional loss can be ignored, but two or more optical fibers are required separately for the optical fiber for transmitting the laser light that excites the object and for receiving the transmitted scattered light (usually, since the scattered light is weak, the number of optical fibers for transmitting the scattered light is larger than that for transmitting the laser light). Therefore, the excitation volume in the object becomes large, and there is a problem that the background light due to autofluorescence and stray light becomes an interference in the measurement.

[0009] Furthermore, in the inventions of Patent Document 1 and Non-Patent Document 1, both have a structure in which a lens and an optical filter are integrated at the tip of the optical fiber. When there is damage to the tip due to repeated use or a need to optimize the tip structure corresponding to the measurement object, the entire optical fiber probe needs to be replaced and adjusted, which poses problems in terms of cost and effort.

[0010] Therefore, the present invention provides an optical fiber probe system that minimizes the excitation volume in an object, has no bending additional loss, is easy to handle, and is inexpensive, and a medical system using this optical fiber probe system.

Means for Solving the Problems

[0011] An optical fiber probe system that irradiates an object with laser light via an optical fiber and receives scattered light, comprising: a first optical fiber that transmits laser light for irradiation from a light source; a hollow second optical fiber that irradiates the object with the laser light from the first optical fiber from its tip and receives scattered light; a third optical fiber that transmits the scattered light received by the second optical fiber to a detector; an optical system having a first optical path that transmits the laser light from the first optical fiber to the second optical fiber and a second optical path that transmits the scattered light from the second optical fiber to the third optical fiber; a coupler that houses the optical system; and a cylindrical outer tube that is connected to the coupler and houses the second optical fiber inside. According to this, by irradiating an object with laser light, using a hollow optical fiber for the optical fiber that receives scattered light, and providing a cylindrical outer tube that houses this optical fiber inside, it is possible to provide an optical fiber probe system that minimizes the excitation volume in the object and has no bending additional loss.

[0012] Furthermore, it may be characterized by further comprising an adjustment mechanism for adjusting the length by which the tip of the second optical fiber protrudes from the tip of the outer tube. According to this, by providing an adjustment mechanism for adjusting the length by which the tip of the second optical fiber protrudes from the tip of the outer tube, it becomes possible to adjust the length according to the characteristics and state of the object.

[0013] Furthermore, the first optical fiber and the third optical fiber may be solid-core optical fibers. According to this, since the first optical fiber and the third optical fiber are solid-core optical fibers, there is no need to worry about bending additional loss between the coupler and the light source / detector. Therefore, the coupler and the second optical fiber beyond it can be freely moved with respect to the light source / detector.

[0014] Furthermore, the second optical fiber may be characterized in that it is detachably attached to the coupler. According to this, since the second optical fiber is detachably attached to the coupler, when the tip of the second optical fiber is damaged or when optimization of the tip structure corresponding to the object is required, only the second optical fiber needs to be replaced, and an optical fiber probe system that is easy to handle and inexpensive can be provided.

[0015] Furthermore, the second optical fiber may be characterized in that it is provided with a lens at the tip. According to this, by providing a lens at the tip of the hollow optical fiber that receives scattered light, background light can be removed.

[0016] Furthermore, the wavelength of the laser light may be excitation light of 785 nm, and the scattered light may be Raman scattered light. According to this, by using a hollow optical fiber for the second optical fiber housed in the outer cylinder tube, the excitation volume is small, the background light is minimized, and bending additional loss does not occur. Therefore, even weak Raman scattered light can be detected.

[0017] In order to solve the above problems, there is provided a medical system including a rigid endoscope, wherein the outer cylinder tube of the above optical fiber probe system is configured as a rigid endoscope. According to this, by irradiating a target such as a lesion in the human body with laser light and configuring a cylindrical outer cylinder tube with a hollow optical fiber housed therein as a rigid endoscope for the optical fiber that receives scattered light, a medical system that can be used for discrimination and diagnosis of lesions in the human body in rigid endoscope surgery and medical robot surgery can be provided.

Advantages of the Invention

[0018] According to the present invention, it is possible to provide an optical fiber probe system that minimizes the excitation volume in an object, has no bending additional loss, is easy to handle and inexpensive, and a medical system using this optical fiber probe system. More specifically, since the hollow optical fiber is fixed within the outer cylindrical tube, the influence of variations in Raman spectrum intensity due to bending additional loss can be reduced. By using solid-core optical fibers for the laser light transmission optical fiber and the scattered light transmission optical fiber, the flexibility between the coupler and the light source / detector is maintained. Due to the characteristics of the hollow optical fiber, the excitation volume at the measurement point of the object becomes extremely small, and unnecessary background light can be minimized. By detachably connecting the hollow optical fiber and the joint, the short hollow optical fiber can be easily and inexpensively replaced.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0020] Hereinafter, with reference to FIGS. 1 to 3, a fiber optic probe system 100 and a medical system 200 including the fiber optic probe system 100 according to an embodiment of the present invention will be described. The fiber optic probe system 100 is a fiber optic probe system that irradiates a target object OBJ with laser light via an optical fiber and receives scattered light scattered when the laser light hits the target object OBJ (shown in FIG. 1). Note that the target object OBJ may be substantially almost all substances, regardless of organic / inorganic substances. However, in the present invention, in addition to the fiber optic probe system 100, since it is assumed that the fiber optic probe system 100 is applied to a medical system 200 (shown in FIG. 2), in this specification, as a preferable target object OBJ, parts and tissues of a living body, for example, internal organs, joints, etc., muscle tissues, supporting tissues, etc. are assumed.

[0021] Further, the laser light is not particularly limited as long as it is an electromagnetic wave with a single wavelength and a strong directivity with the phases aligned, and an appropriate wavelength is selected as appropriate according to the field in which the fiber optic probe system 100 is used. For example, when performing Raman spectroscopy using the fiber optic probe system 100, the excitation wavelength of the laser light is preferably 785 nm. When performing Brillouin spectroscopy, depending on the target and purpose, various excitation wavelengths such as violet / ultraviolet (<400 nm), blue (400 nm to 500 nm), green (500 nm to 560 nm), yellow (560 nm to 600 nm), red (600 nm to 750 nm), near infrared (750 nm to 1300 nm), etc. are used.

[0022] The fiber optic probe system 100 includes a solid-type first optical fiber 10, a hollow second optical fiber 20, a solid-type third optical fiber 30, an optical system 41 that transmits excitation light and scattered light, a coupler 40 that houses the optical system 41, a cylindrical outer tube 50 that houses the second optical fiber 20 inside, an adjustment mechanism 60 that adjusts the length by which the tip of the second optical fiber 20 protrudes from the tip of the outer tube 50, a lens 21 attached to the tip of the second optical fiber 20, a laser diode 70 that functions as a light source for excitation light, and a Raman spectrometer 80 that functions as a detector for scattered light.

[0023] The laser diode 70 is a circuit element that generates laser light (excitation light) for irradiating the object OBJ. Since the optical fiber probe system 100 in this embodiment includes a Raman spectrometer 80 as a detector and is assumed to perform Raman spectroscopy, the wavelength of the laser light generated by the laser diode 70 is preferably excitation light of 785 nm.

[0024] The first optical fiber 10 is a solid-type optical fiber having one end connected to the laser diode 70 and the other end connected to the coupler 40, and transmits the laser light generated by the laser diode 70 to the optical system 41 in the coupler 40. More specifically, the first optical fiber 10 is a silica multimode fiber with a core diameter of 105 μm and NA 0.1. However, the first optical fiber 10 is not limited thereto, and for example, it may be a single-mode optical fiber in terms of structure or a plastic optical fiber in terms of material.

[0025] Note that in the optical fiber probe system 100, during its use, the laser diode 70 is arranged at a position somewhat separated from the coupler 40, and there may be a movable part therebetween. Therefore, considering the bending additional loss, it is preferably a solid type. Since the first optical fiber 10 is a solid type, there is no need to worry about the bending additional loss between the coupler 40 and the laser diode 70. Therefore, the coupler 40 and the second optical fiber 20 beyond it can be freely moved with respect to the laser diode 70. However, when there is no movable part between the laser diode 70 and the coupler 40, or when it is ensured that there is no need to consider the bending additional loss even if there is a movable part, the first optical fiber 10 does not need to be a solid type, and for example, it may be a hollow optical fiber similar to the second optical fiber 20.

[0026] Also, in the aluminum coupler 40, a collimator 421 with a focal length of 4.51 mm is provided at the connection portion between the first optical fiber 10 and the coupler 40. The laser light transmitted from the first optical fiber 10 is collimated in parallel by the collimator 421 and emitted to the optical system 41. The collimator 421 incorporates a laser line filter for a wavelength of 785 nm, and this filter removes the noise of the excitation laser light generated during the transmission of the first optical fiber 10.

[0027] The optical system 41 housed in the coupler 40 has a first optical path 411 for transmitting laser light from the first optical fiber 10 to the second optical fiber 20 and a second optical path 412 for transmitting scattered light from the second optical fiber 20 to the third optical fiber 30. The first optical path 411 is formed by the collimator 421, a silver prism mirror 43 fixed to the micromotion stage in the coupler 40, a long-pass filter 44 fixed to the mount in the coupler 40 that reflects the wavelength of the excitation light and transmits the wavelength of the scattered light, and a collimator 422 with a focal length of 18.4 mm that connects the first optical path 411 and the second optical fiber 20. The laser light focused by the collimator 421 is reflected by the prism mirror 43, the laser light reflected by the prism mirror 43 is further reflected by the long-pass filter 44, and the laser light reflected by the long-pass filter 44 enters the collimator 422.

[0028] The second optical path 412 is formed by a collimator 422 that emits the scattered light emitted from the second optical fiber 20 and a collimator 423 that collimates the scattered light that has passed through the long-pass filter 44 after being parallelized by the collimator 422 and emits it to the third optical fiber 30. The optical axes of the collimator 422 and the collimator 423 are arranged to be on the same optical axis as the optical axis of the scattered light from the second optical fiber 20. Therefore, the second optical path 412 has an optical axis consisting of a straight line. Note that the collimator 421 is arranged such that the optical axis emitted by the collimator 421 forms an angle of 12 degrees with the optical axis of the second optical path 412. The collimator 423 with a focal length of 11.07 mm condenses the scattered light incident from the second optical path 412 and emits it to the third optical fiber 30.

[0029] The third optical fiber 30 has one end connected to the coupler 40 and the other end connected to the Raman spectrometer 80, and transmits the scattered light emitted by the collimator 423 to the Raman spectrometer 80. More specifically, the third optical fiber 30 is a bundle fiber formed by bundling seven quartz multimode fibers with a core diameter of 200 μm and an NA of 0.22. On the coupler 40 side, the seven fibers are closely bundled, and on the Raman spectrometer 80 side, they are arranged linearly. However, the third optical fiber 30 is not limited to this, like the first optical fiber 10. For example, it may be a single-mode optical fiber in terms of structure, or it may be made of plastic in terms of material.

[0030] Note that during use, like the laser diode 70, the Raman spectrometer 80 is arranged at a certain distance from the coupler 40, and there may be a movable part between them. Therefore, considering the bending additional loss, it is preferably a filled type. Since the third optical fiber 30 is of the filled type, there is no need to worry about the bending additional loss between the coupler 40 and the Raman spectrometer 80. Therefore, the coupler 40 and the second optical fiber 20 ahead of it can be freely moved with respect to the Raman spectrometer 80. However, when there is no movable part between the Raman spectrometer 80 and the coupler 40, or when it is ensured that there is no need to consider the bending additional loss even if there is a movable part, the third optical fiber 30 does not need to be of the filled type. For example, it may be a hollow optical fiber similar to the second optical fiber 20.

[0031] The Raman spectrometer 80 performs Raman spectroscopy detection. When a substance is irradiated with light, in addition to reflection, refraction, absorption, etc. due to the interaction between light and the substance, a phenomenon called scattering occurs. Among the scattered light, there is Rayleigh scattering in which light with the same wavelength as the incident light is scattered, and Raman scattering in which the light is scattered at a wavelength different from the incident light due to molecular vibration. The Raman spectrometer 80 spectroscopically analyzes Raman scattered light, which is much weaker than Rayleigh scattering, and analyzes the molecular-level structure from the obtained Raman spectrum. When the optical fiber probe system 100 is used in the medical field, the Raman spectrometer 80 can be used to obtain biological information of biological tissues. For example, it is possible to detect slight changes in the tissue composition to distinguish normal tissues from diseased tissues and perform tissue analysis.

[0032] The second optical fiber 20 is a hollow optical fiber having a lens 21 at the tip on the other end side, with one end connected to a collimator 422 attached to the coupler 40. Thereby, the second optical fiber 20 transmits the laser light emitted from the collimator 422 to the lens 21 and irradiates the object OBJ with the excitation light through the lens 21, and at the same time transmits the scattered light received by the lens 21 to the Raman spectrometer 80 through the collimator 422. More specifically, the hollow second optical fiber 20 has a silver thin film formed on the inner surface of a glass capillary tube with an inner diameter of 1 mm, and can transmit laser light with an excitation wavelength of 785 nm and Raman scattered light (more precisely, Stokes Raman scattered light) with low loss.

[0033] In this way, by using a hollow optical fiber for the second optical fiber 20, the excitation volume is small, the background light is minimized, and bending additional loss does not occur, so that even weak Raman scattered light can be detected. Note that the inner diameter of the second optical fiber 20 is not limited to 1 mm, and is appropriately selected in the range of approximately 250 μm to 2 mm. Also, the outer diameter of the second optical fiber 20 is about 1.6 mm when the inner diameter is 1 mm, but this is also not limited, and is appropriately selected according to the inner diameter of the outer cylinder tube 50 described later.

[0034] The lens 21 has a ball-shaped lens with the same inner diameter fixed to the tip of the second optical fiber 20 by UV curable resin. The excitation light transmitted through the second optical fiber 20 is condensed, and the excitation light is emitted to an object OBJ such as a biological tissue in contact with or close to the tip, exciting the object OBJ. Further, the lens 21 receives the scattered light from the excited object OBJ and emits it to the second optical fiber 20. In this way, by providing a ball-shaped lens 21 with the same inner diameter at the tip of the hollow second optical fiber 20, unnecessary background light generated from outside the condensing point can be removed. Therefore, it is preferable to provide the lens 21. Thereby, Raman scattered light from the condensing point can be detected with a high signal-to-noise ratio. The lens 21 is not limited to a ball-type lens. For example, a cylindrical shape with an obliquely polished tip can realize a side-irradiation type lens function.

[0035] The outer cylinder tube 50 is connected to the coupler 40, more precisely, to the SMA connector connected to the collimator 422. It has a hollow cylindrical shape inside and houses the second optical fiber 20 therein. The outer cylinder tube 50 has an outer diameter of about 5 mm and an inner diameter appropriately selected to accommodate the second optical fiber 20. The overall shape is a linear cylindrical shape with a length of about 10 to 30 cm and is made of a material that does not deform (for example, made of metal or hard plastic). In this way, since the outer cylinder tube 50 is linear and does not deform, the second optical fiber 20 housed inside is fixed linearly and maintained. The outer cylinder tube 50 may have a gentle curvature. In this case, since the second optical fiber 20 is bent along the curvature of the outer cylinder tube 50, additional loss due to bending is added. However, since the inner second optical fiber 20 having an outer diameter smaller than the inner diameter of the outer cylinder tube 50 can be stably fixed, fluctuations during measurement can be further suppressed. Also, in in-vivo measurements, a gentle curvature may enable measurement of sites where measurement is difficult with a linear outer cylinder tube.

[0036] Since the second optical fiber 20 has a hollow shape, scattered light and excitation light transmitted inside may be lost due to deformation such as bending. However, as described above, by irradiating the object OBJ with laser light and using the hollow second optical fiber 20 for the optical fiber that receives the scattered light, and providing the cylindrical outer tube 50 that houses the second optical fiber 20 therein, it is possible to minimize the excitation volume in the object OBJ and provide the optical fiber probe system 100 that has no bending additional loss.

[0037] Note that the second optical fiber 20 may be configured to be detachably attached to the coupler 40, more precisely, the SMA connector connected to the collimator 422. The detachable attachment configuration may be, for example, a plug-in type or a screw type, and is not particularly limited. In this way, since the second optical fiber 20 is detachably attached to the coupler 40, when the tip of the second optical fiber 20 is damaged or when optimization of the tip structure corresponding to the object OBJ is required, only the second optical fiber 20 needs to be replaced, and an optical fiber probe system 100 that is easy to handle and inexpensive can be provided.

[0038] The adjustment mechanism 60 is configured to adjust the length by which the tip of the second optical fiber 20 protrudes from the tip of the outer tube 50 during use. When a lens 21 is attached to the tip of the second optical fiber 20, the adjustment mechanism 60 is configured to adjust the length by which the lens 21 protrudes from the tip of the outer tube 50. The configuration in which the length is adjustable may be, for example, a screw type, and is not particularly limited. In this way, by providing the adjustment mechanism 60 that adjusts the length by which the tip of the second optical fiber 20 or the lens 21 protrudes from the tip of the outer tube 50 during use, it becomes possible to adjust the length in order to maximize the light collection efficiency according to the characteristics and state of the object OBJ.

[0039] Also, as shown in FIG. 2, the optical fiber probe system 100 can be applied to a medical system 200 including a rigid endoscope 220. The medical system 200 includes a medical system control device 210 for overall control, a rigid endoscope 220 which is a type of endoscope inserted into the human body, and an arm 230 for driving the rigid endoscope 220 attached to the tip, and is used for discrimination and diagnosis of lesions in the human body in rigid endoscope surgery and medical robot surgery. In the medical system 200, in the optical fiber probe system 100, a coupler 40 is attached to the tip of the arm 230, and the outer cylinder tube 50 is configured as the rigid endoscope 220.

[0040] The medical system control device 210 may drive and control the arm 230, and may include a laser diode 70 and a Raman spectrometer 80 inside to provide excitation light to the tip of the rigid endoscope 220 and receive scattered light from the rigid endoscope 220. Although it passes through the arm 230 which is a movable part in the middle, since it passes through the solid-core first optical fiber 10 and the third optical fiber 30 from the coupler 40 to the medical system control device 210, bending additional loss can be prevented.

[0041] According to this, by irradiating a target such as a lesion in the human body with laser light and configuring the outer cylinder tube 50 with a hollow second optical fiber 20 accommodated inside as the rigid endoscope 220 in the optical fiber, a medical system 200 can be provided for use in discrimination and diagnosis of lesions in the human body in rigid endoscope surgery and medical robot surgery.

[0042] FIG. 3 shows the Raman spectra of cartilage measured by the optical fiber probe system 100 and a commercial product. According to this Raman spectrum, the optical fiber probe system 100 can significantly reduce background light and clearly measure Raman bands (arrow parts) derived from biological tissues.

[0043] As described above, according to the present invention, it is possible to provide an optical fiber probe system 100 that minimizes the excitation volume in the object OBJ, has no bending additional loss, is easy to handle, and is inexpensive, and a medical system 200 using this optical fiber probe system 100. More specifically, since the hollow first optical fiber 10 is fixed within the outer cylindrical tube 50, it is possible to reduce the influence of variations in Raman spectrum intensity due to bending additional loss. By using solid-core optical fibers for the first optical fiber 10 which is a laser light transmission optical fiber and the third optical fiber 30 which is a scattered light transmission optical fiber, the flexibility between the coupler 40 and the light source / detector is maintained. Due to the characteristics of the hollow optical fiber, the excitation volume at the measurement point of the object OBJ becomes extremely small, and unnecessary background light can be minimized. By detachably connecting the first optical fiber 10 and the coupler 40, the short first optical fiber 10 can be easily and inexpensively replaced.

[0044] Note that the present invention is not limited to the illustrated embodiments, and can be implemented with configurations that do not deviate from the content described in each item of the claims. That is, although the present invention is mainly illustrated and described with respect to specific embodiments, those skilled in the art can make various modifications to the above-described embodiments in terms of quantity and other detailed configurations without departing from the scope of the technical idea and purpose of the present invention.

Explanation of Reference Numerals

[0045] 100 Optical fiber probe system 10 Excitation light transmission optical fiber (first optical fiber) 20 Second optical fiber 21 Ball lens 30 Detection light transmission optical fiber (third optical fiber) 40 Coupler 41 Optical system 411 First optical path 412 Second optical path 42 Collimator 43 Prism mirror 44 Long-pass filter 50 Outer cylinder tube 60 Adjustment mechanism 70 Laser diode 80 Raman spectrometer (detector) 200 Medical system 210 Medical system control device 220 Rigid endoscope 230 Arm OBJ Object

Claims

1. An optical fiber probe system that irradiates an object with laser light via an optical fiber and receives scattered light, comprising: a first optical fiber that transmits laser light for irradiation from a light source; a hollow second optical fiber that irradiates the object from its tip with the laser light from the first optical fiber and receives scattered light; a third optical fiber that transmits the scattered light received by the second optical fiber to a detector; an optical system having a first optical path for transmitting the laser light from the first optical fiber to the second optical fiber and a second optical path for transmitting the scattered light from the second optical fiber to the third optical fiber; a coupler that houses the optical system; a cylindrical outer tube that is connected to the coupler and houses the second optical fiber inside; An optical fiber probe system comprising the above.

2. The optical fiber probe system according to claim 1, further comprising an adjustment mechanism for adjusting the length by which the tip of the second optical fiber protrudes from the tip of the outer tube.

3. The optical fiber probe system according to claim 1, wherein the first optical fiber and the third optical fiber are solid-core optical fibers.

4. The optical fiber probe system according to claim 1, wherein the second optical fiber is detachably attached to the coupler.

5. The optical fiber probe system according to claim 1, wherein the second optical fiber is provided with a lens at its tip.

6. The wavelength of the laser light is excitation light of 785 nm, The scattered light is Raman scattered light, The optical fiber probe system according to claim 1, characterized by the above.

7. A medical system comprising a rigid endoscope, A medical system in which the outer tube of the optical fiber probe system according to any one of claims 1 to 6 is configured as a rigid endoscope.

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