JP4538258B2 - Thin diameter fiberscope and manufacturing method thereof - Google Patents

Description

  The present invention relates to a meridian fiberscope used for observing a narrow part or the like in the medical field or industrial application, and a manufacturing method thereof.

  A fiberscope (endoscope) is widely used as a medical device that can directly observe a part in a living body. In particular, in addition to a fiberscope having a diameter (diameter) of 3 to 4 mm, for example, φ is 2 mm or less. A small diameter fiberscope has also been developed. This thin fiberscope enables direct observation of extremely small areas such as blood vessels, mammary glands, and pancreatic ducts in addition to the conventional digestive organs, respiratory organs, urinary organs, etc. Has expanded to.

  This type of thin fiberscope is disclosed in, for example, “Ultrafine medical fiberscope” (see Non-patent Document 1), “Medical ultrafine image fiber and its application” (see Nonpatent Document 2), and the like. As described above, a fusion-integrated image fiber sharing a cladable cladding and a light guide fiber for guiding an irradiation light to an observation object are placed in a tube made of metal such as stainless steel (SUS) having a diameter of 2 mm or less. It has an insertion portion structure that is inserted and fixed by an adhesive.

  Here, as a manufacturing method of the thin fiberscope having the integrated insertion portion structure, a manufacturing method of the integrated insertion portion will be described with reference to FIGS.

  That is, according to the conventional manufacturing method of the small diameter fiberscope 100 (insertion portion), one end portion 101a of the light guide fiber 101, one end portion 103a of the image fiber 103, and one end portion corresponding to the tube 104 are thermosetting. The one end 101a and the one end 103a immediately after application of the adhesive are integrally inserted into the tube 104.

  In this insertion process, the one end 101a of the light guide fiber 101 and the one end 103a of the image fiber 103 are inserted into the tube 104 so that the end of the one end is exposed outward from the end of the one end 104a of the tube 104 by a predetermined length. To do. Note that a portion exposed to the distal end side with respect to the objective lens 102 a of the objective lens 102 in the fiber scope 100 is referred to as an extra length portion 111.

  After the insertion step, the tube 104 is heated to cure the adhesive 110, and the light guide fiber one end 101 and the image fiber one end 103a are fixed in the tube 104.

Next, after the adhesive is cured, the surplus length portion 111 is polished, and finally, the object surface 102a of the objective lens 102 is polished to the boundary line CC along the object surface 102a of the objective lens 102. The adhesive 110 covered on the surface is peeled off without polishing.
Mitsubishi Cable Industries, “Development of small diameter medical fiberscope”, Mitsubishi Cable Industrial Times, separate volume No. 75 (1988. 4) P.I. 1-P. 10 Takashi Tsunuma, Kazuo Sanada, “Medical Ultra Fine Diameter Image Fiber and its Applications”, Fujikura Co., Ltd., Fujikura Technique No. 84, Reprint 1993

  However, in the conventional manufacturing method of the small-diameter fiberscope 100, the heat shrinkage of the adhesive 110 due to the heating of the tube 104 and the difference in thermal expansion between the members constituting one end of the fiberscope {particularly, the metal tube 104 (heat Thermal stress (stress) is generated between the members due to the difference in thermal expansion between the large expansion) and other members.

  In particular, a tensile stress is applied to the one end portion 103 a of the image fiber along the longitudinal direction thereof, that is, a stress is applied in a direction in which the objective lens 102 and the image fiber 103 are separated from each other. There was a risk of damage such as peeling (see FIG. 7).

  Due to damage such as peeling of the joint surface between the objective lens 102 and the image fiber 103, a noise component is included in the image of the observation object obtained through the image fiber 103, and the obtained observation is obtained. There was a possibility of deteriorating the visibility of the target image.

  In addition, when peeling occurs on the joint surface between the objective lens 102 and the image fiber 103, there is a possibility that a defect may occur due to poor joint between the objective lens 102 and the image fiber 103.

  Separation of the joint surface between the objective lens 102 and the image fiber 103 occurs particularly when a metal medium passage tube such as SUS is similarly fixed in the tube 104 in parallel with the image fiber 103. Since heat stress due to the passage tube is further applied, it is particularly likely to occur. In the case of the thin fiberscope 100 with a metal medium passage tube integrated type, special care is required.

  The present invention has been made in view of the above-described circumstances, and provides a thin fiber scope capable of preventing occurrence of damage such as peeling between an optical component such as an objective lens and a joint surface of an image fiber, and a manufacturing method thereof. Its purpose is to provide.

In order to solve the above-mentioned problem, the first aspect of the present invention is that the irradiation light irradiation side one end portion of the light guide fiber that propagates the irradiation light and irradiates the object, and an optical component are joined to reflect the reflected light from the object. in a state where one end portion including the optical components of the image fiber which propagated light is inserted into the hollow of the hollow outer portion, a small diameter fiberscope comprising fixed to the hollow shape exterior portion by adhesives a manufacturing method, the periphery of the optical component joint at least in the image fiber includes a first coating step of coating a thermal stress absorbing buffer layer made of an elastic resin, the optical coated by the coating process The image fiber end including the component joint and the irradiation light irradiation side one end of the light guide fiber are bonded to the hollow exterior portion by an adhesive applied thereto. And gist to be secured.

According to a second aspect of the invention, to solve the above problems, before Symbol coating process, attaching the elastic resin around the end portion by dipping the image fiber end portion including said optical component in a bath of elastic resin And a step of curing the elastic resin attached around one end of the image fiber to form the first thermal stress absorbing buffer layer.

  In order to solve the above-mentioned problem, the thin fiberscope includes a medium passage tube having one end inserted and fixed in the hollow exterior portion, and the periphery of the medium passage tube is surrounded by the tube. The gist is to include a step of covering with a second heat stress absorbing buffer layer.

In order to solve the above-mentioned problem, the invention according to claim 4 reflects the reflection from the object by joining one end of the irradiation light irradiation side of the light guide fiber that propagates the irradiation light and irradiating the object, and an optical component. in a state where one end portion including the optical components of the image fiber which propagates receives light is inserted into the hollow of the hollow outer portion, a small diameter fiber composed is secured to the hollow-shaped exterior portion by adhesives A scope, which is formed of an elastic resin, includes a first thermal stress absorption buffer layer that covers at least the periphery of the optical fiber joint of the image fiber , and the first thermal stress absorption buffer layer covers the first thermal stress absorption buffer layer said image fiber end portion including said optical component joint which is, this that said irradiation light irradiation side end of the light guide fiber is secured to the hollow outer portion by the adhesive The the gist.

  In order to solve the above problem, the invention according to claim 5 is characterized in that the first thermal stress absorbing buffer layer covers the entire periphery of one end of the image fiber including the optical component.

  In order to solve the above problem, the invention according to claim 6 is a medium passage tube having one end inserted and fixed in the hollow exterior portion, and a second thermal stress covering the periphery of the medium passage tube. And a buffer layer for absorption.

According to the first and fourth aspects of the present invention, when the hollow exterior portion is heated, the thermal stress generated from the hollow exterior portion and acting on the optical component joint portion is caused around the joint portion. Since it can be absorbed by the first thermal stress absorbing buffer layer made of the formed elastic resin , damage such as peeling occurs on the joint surface between one end of the image fiber and the optical component due to thermal stress. Can be prevented.

  According to the second aspect of the present invention, the first thermal stress absorbing buffer layer is formed by dipping one end portion of the image fiber including the optical component into an elastic resin tank and adhering the elastic resin around the one end portion. Therefore, even if one end of the image fiber has a small diameter, the first thermal stress absorbing buffer layer can be easily formed.

  According to the third and sixth aspects of the present invention, when the hollow exterior portion is heated, the thermal stress generated from the medium passage tube and acting on the optical component joint is formed around the medium passage tube. Can be absorbed by the second buffer layer for absorbing thermal stress, and damage such as peeling occurs at the joint surface between the image fiber one end and the optical component due to thermal stress generated from the medium passage tube. Can be prevented.

  According to the fifth aspect of the present invention, since the entire periphery of the one end portion of the image fiber can be covered with the first heat stress absorbing buffer layer, the thermal stress generated from the hollow exterior portion with respect to the one end portion of the image fiber The influence can be further reduced.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1A to 1C, a thin fiberscope 1 according to an embodiment of the present invention has a thin outer diameter of about 0.5 mm to 0.9 mm, for example, SUS or the like. Tube 2 which is a metal hollow exterior portion, a bundle-type light guide fiber 3 composed of a large number of fibers having an outer diameter of about 20 μm to 50 μm, and an image fiber 4 as an image transmission medium. Yes.

  The image fiber 4 has a fusion-integrated structure in which a plurality of core portions are integrated by a shared cladding portion. Due to the shared clad structure, the outer diameter (coating diameter) of the image fiber 4 is very small, for example, about 200 to 500 μm.

  The image fiber 4 has an objective lens 5 joined to, for example, an adhesive or the like at one end 4a on the side facing the observation object.

  The one end 3 a on the irradiation side of the light guide fiber 3 and the one end 4 a on the objective lens joining side of the image fiber 4 are inserted and integrated into the tube 2, and the integrated insertion portion 10 in the fiber scope 1 is integrated. It is composed.

  In this embodiment, the tip end 4a1 to which the objective lens 5 is bonded at the image fiber one end 4a has a slightly shorter fiber diameter than the other portions, and this tip 4a1 (hereinafter also referred to as the joint 4a1). And a buffer layer 12 for absorbing the difference (thermal expansion difference) between the thermal expansion coefficient of the image fiber 4 and the thermal expansion coefficient of other members, particularly the tube 2, is formed around the objective lens. The periphery of the joint 4a1 is covered with the buffer layer 12.

  On the other hand, the other end side of the light guide fiber 3 and the other end side of the image fiber 4 are branched via a branching portion 12, and the other end portion 3b of the branched light guide fiber 3 is opposed to the light source as an illumination light entrance. The other end 4b of the image fiber 4 is connected to an observation image display TV monitor via an eyepiece lens system and a TV camera.

  According to the thin fiberscope 1 configured as described above, the light emitted from the light source is light in a state where the distal end of the integrated insertion portion 10 faces the observation target, for example, a desired organ in the living body. It is guided through the guide fiber 3 and irradiated to the observation target organ.

  At this time, the reflected light from the observation target organ constituting the image of the observation target organ is collected by the objective lens 5 and transmitted through the image fiber 4 to be transmitted as an image through the eyepiece lens system and the TV camera as a TV monitor. And displayed on the TV monitor.

  As a result, the observer can observe the image of the organ to be observed that is imaged through the TV camera and displayed through the TV monitor.

  A manufacturing method of the thin fiberscope 1 configured as described above will be described with reference to FIGS.

  As shown in FIG. 2A, an elastic resin having high elasticity such as polyimide resin or urethane resin is provided around the joint 4a1 in the image fiber 4 in which the objective lens 5 is joined to the joint 4a1 in advance. For example, the elastic resin layer, that is, the thermal stress absorbing buffer layer 12 is formed by coating so as to have a thickness of several μm to several hundred μm (see FIG. 2A and step S1 in FIG. 3).

  Next, as shown in FIG. 2B, the image fiber 4 in which the buffer layer 12 is formed in the joint 4a1 is formed in the gap between the fibers constituting the light guide fiber 3, and the objective surface 5a of the objective lens 5 is provided. The light guide fiber is inserted from the distal end of the one end portion 3a until reaching a position inside a predetermined length along the longitudinal direction.

Subsequently, the thermosetting adhesive 15 is applied to the inner surface of the light guide fiber one end 3a, the image fiber one end 4a including the objective lens 5 and the buffer layer 12, and the corresponding one end 2a in the hollow portion of the tube 2, respectively. Apply (see step S2 in FIG. 3)
Following application of the adhesive, the light guide fiber 3 and the image fiber 4 are integrally inserted into the tube 2 from the one end portions 3a and 4a side, and the tip end of the one end is exposed outward from the tip end 2b of the tube end portion 2a by a predetermined length. (See FIGS. 2B to 2C and step S3). At this time, a portion exposed to the distal end side with respect to the objective lens 5a of the objective lens 5 in the fiberscope 1 is defined as a surplus length portion 20.

  Next, the tube 2 in which the light guide fiber one end 3a and the image fiber one end 4a are inserted is heated to cure the adhesive 15, and the light guide fiber one end 3a and the one end 4a of the image fiber 4 are placed in the tube 2. (See FIG. 2C and step S4).

  At this time, the curing shrinkage of the adhesive 15 due to the heating of the tube 2 and the thermal expansion difference between the members constituting one end of the fiberscope {particularly, the thermal expansion difference between the metal tube 2 (large thermal expansion) and other members. }, Thermal stress (stress) is generated between the members, and this thermal stress also acts on the joint portion 4a1 of the image fiber 4 to which the objective lens 5 is joined.

  However, according to the present embodiment, the thermal stress absorbing buffer layer 12 made of an elastic resin is formed around the image fiber joint 4a1, so that the thermal stress acting on the image fiber joint 4a1 is caused by the buffer layer. 12 is absorbed.

  Therefore, it is possible to weaken the action of the thermal stress generated due to the heating of the tube 2 on the image fiber joint 4a1.

  Finally, the excess length portion 20 is gradually polished by, for example, a polishing machine, and finally polished to the boundary line along the objective surface 5a of the objective lens 5 (see FIG. 2D). Without polishing the objective surface 5a of the lens 5, the adhesive 15 covered on the surface is peeled off, and the manufacture of the fiberscope 1 is completed.

  As described above, according to this embodiment, since the periphery of the image fiber joint 4a1 to which the objective lens 5 is joined is covered with the buffer layer 12 for absorbing thermal stress made of an elastic resin, the image fiber is used. The thermal stress that has acted on the joint 4a1 can be absorbed by the buffer layer 12.

  As a result, it is possible to reduce the adverse effect of the thermal stress generated due to the heating of the tube 2 on the image fiber joint 4a1, and the image fiber one end 4a including the light guide fiber one end 3a and the objective lens 5 is connected to the tube 2. It can be fixed in a stable state, and the occurrence of damage such as peeling of the joint surface of the objective lens 5 and the image fiber 4 can be prevented.

  As a result, the visibility of the image to be observed can be maintained high.

  In addition, since the image fiber bonding portion 4a1 is covered with the buffer layer 12, the bonding relationship between the objective lens 5 and the image fiber 4 can be strengthened, and bonding failure between the objective lens 5 and the image fiber 4 can be prevented. be able to.

  In this embodiment, the elastic resin is applied around the image fiber joint 4a1 to form the buffer layer 12. However, the present invention is not limited to this configuration, and a thin wall formed of the elastic resin is used. You may adhere | attach a tube around the junction part 4a1.

  Further, instead of the above coating step, as shown in FIG. 4, one end portion 4a (objective lens) of the image fiber 4 with respect to the elastic resin stock solution in the tank 30 in which a stock solution of an elastic resin such as polyimide resin or urethane resin is previously contained. 5 and the joint 4a1) may be immersed (dipped) to attach an elastic resin around the image fiber one end 4a, and the attached elastic resin may be cured to form the buffer layer 12. According to the step of forming the buffer layer 12 by the dip, the elastic resin can be easily attached to the one end 4a even if the image fiber one end 4a has a small diameter. In addition, you may give the function which blocks the light from the outside by using black resin as elastic resin.

  If a desired layer thickness cannot be obtained by one dipping, the buffer layer 12a can be formed on the entire image fiber one end 4a by repeating the dipping process as shown in FIG. .

  According to this modification, since the entire image fiber one end 4a can be covered with the buffer layer 12, the influence of the thermal stress generated from the tube 2 on the image fiber one end 4a can be further reduced. Although the buffer layer 12a is also formed on the objective surface 5a side of the objective lens 5, since it is polished by the above-described polishing step, there is no possibility of affecting the function of the objective lens 5.

  Further, the image fiber tip 4a1 may be electrolessly plated with nickel or the like in order to reduce the force of pulling or bending, and may be further electrolyzed to obtain a desired layer thickness. is there.

  On the other hand, in the present embodiment, the light guide fiber 3 and the image fiber 4 are integrally inserted into the tube 2 from the one end portions 3a and 4a side and fixed in the tube 2, but the present invention is limited to this configuration. For example, the present invention can be applied to a case where at least one metal medium passage tube 40 is inserted and fixed in the tube 2 together with the light guide fiber 3 and the image fiber 4.

  The medium passage tube 40 is provided in order to add various media and apply an external action to the object and / or its surroundings when photographing the object by the thin fiberscope 1A.

  For example, when the object is a living body or the like, when the visual field cannot be secured with blood or the like, the visual field is secured by circulating the physiological saline or the like as the medium through the medium passage tube 40 to the object and flushing the blood or the like. Can do. In addition, when the object is crushed by a living body tube or the like and the field of view cannot be secured, air as a medium is supplied to the object through the medium passage tube 40 to expand the tube and secure the field of view. Can do.

  Furthermore, if necessary, forceps or a fiber as a medium can be inserted through the medium passage tube 40 to cut a part of the object or grasp the periphery thereof.

  Also in the case of manufacturing the thin fiber scope 1A including the medium passage tube 40, a manufacturing method similar to the manufacturing method of the thin fiber scope 1 shown in FIGS. 2 and 3 can be basically applied.

  That is, as shown in FIG. 5A, the thickness of the elastic resin having high elasticity such as polyimide resin or urethane resin is several μm to several hundred μm, for example, with respect to the periphery of the medium passage tube 40. Thus, an elastic resin layer, that is, a thermal stress absorbing buffer layer 41 is formed by coating (or by dipping) (see FIG. 5A and step S1 in FIG. 3).

  Next, in addition to the insertion of the image fiber 4 in which the buffer layer 12 is formed in the joint 4 a 1 described above, the medium path tube 40 in which the buffer layer 41 is formed is placed in the gap between the fiber groups constituting the light guide fiber 3. The light guide fiber 3 is inserted and exposed from the tip of the one end 3a.

  Next, as shown in step S1, the thermosetting adhesion to the light guide fiber one end 3a, the image fiber one end 4a, the medium passage tube 40 insertion side one end 40a, and the inner surface of the tube one end 2a, respectively. In a state where the agent 15 is applied, the light guide fiber 3, the image fiber 4, and the medium passage tube 40 are integrally inserted into the tube 2 from the end portions 3a, 4a, and 40a side, and the tip end of the end portion is connected to one end of the tube. It is exposed from the front end 2b outward by a predetermined length (see FIGS. 5B to 5C and steps S2 to S3 in FIG. 3). Note that a portion exposed to the distal end side with respect to the objective lens 5a of the objective lens 5 in the fiberscope 1 is referred to as an extra length portion 20A.

  Next, the tube 2 in which the light guide fiber one end 3a, the image fiber one end 4a, and the medium passage tube one end 40a are inserted is heated to cure the adhesive 15, and the light guide fiber one end 3a and one end of the image fiber are cured. The portion 4a and the medium passage tube one end portion 40a are integrally fixed in the tube 2 (see FIG. 5C and step S4).

  At this time, the heat shrinkage of the adhesive 15 due to the heating of the tube 2 and the difference in thermal expansion between the members constituting one end of the fiberscope {particularly, the metal tube 2 and the medium passage tube 40 (large thermal expansion) and the other Thermal stress (stress) is generated between the members due to the difference in thermal expansion between the members, and this thermal stress also acts on the joint 4a1 of the image fiber 4 to which the objective lens 5 is joined.

  However, according to this modification, since the thermal expansion difference absorbing buffer layer 12 made of an elastic resin is formed around the image fiber joint 4a1, the thermal stress acting on the image fiber joint 4a1 is buffered. Absorbed by layer 12. Further, since the buffer layer 41 for absorbing thermal expansion made of an elastic resin is formed around the medium passage tube 40, the thermal stress generated from the medium passage tube 40 is absorbed by the buffer layer 41.

  Therefore, it is possible to weaken the action of the thermal stress generated due to the heating of the tube 2 on the image fiber joint 4a1.

  Finally, by polishing the excess length portion 20A (see FIG. 5D), the thin fiber scope 1A including the medium passage tube 40 can be manufactured.

  As described above, in the present modification, the thin fiberscope 1A includes the metal tube 2 and the medium passage tube 40, respectively. Therefore, when the tube 2 and 40 portion (metal portion) are heated, It is expected that the thermal stress generated from the metal part is also large.

  However, according to the present modification, the thermal stress caused by the metal tube 2 and the medium passage tube 30 can be absorbed by the buffer layers 12 and 41, so that the objective lens 5 and the image fiber 4 are joined together. The occurrence of damage such as peeling off can be prevented, and further, the joining relationship between the objective lens 5 and the image fiber 4 can be strengthened to prevent joining failure between the objective lens 5 and the image fiber 4.

  In the present embodiment and its modifications, the metal tube having a high coefficient of thermal expansion has been described as the tube and the medium passage tube. However, the present invention is not limited to this configuration, and is manufactured from other materials. The manufacturing method of the present invention can also be applied to a thin fiberscope using a formed tube. It is particularly preferable to apply the manufacturing method of the present invention to a thin fiberscope using a tube manufactured from a material having a high coefficient of thermal expansion such as metal.

  Further, in the present embodiment and the modification thereof, the objective lens bonded to the image fiber is taken as an example of the optical component. However, the present invention is not limited to this configuration. Any optical component may be used as long as it is fixed to the optical member.

  Furthermore, the manufacturing method of the present invention can also be applied to the case where a metal part other than the medium passage tube is inserted into and fixed to the tube together with the light guide fiber and the image fiber.

(A) is a figure which shows the whole structure of the thin fiberscope concerning embodiment of this invention, (b) is AA arrow sectional drawing in Fig.1 (a), (c) is FIG. It is BB arrow sectional drawing in b). (A) is schematic sectional drawing which shows the buffer layer formation process concerning embodiment of this invention, (b) inserts the light guide fiber and image fiber concerning embodiment of this invention integrally in a tube. It is a schematic sectional drawing which shows a process and an adhesive application | coating process, (c) is a schematic sectional drawing which shows the heating process of a tube, (d) is a schematic sectional drawing which shows the state after surplus length part grinding | polishing. It is a schematic flowchart which shows the manufacturing process of the small diameter fiberscope concerning embodiment of this invention. It is a figure which shows the modification of the buffer layer formation process in embodiment of this invention. (A) is schematic sectional drawing which shows the buffer layer formation process to the tube for medium passages concerning the modification of embodiment of this invention, (b) is the light guide concerning the modification of embodiment of this invention. It is a schematic sectional drawing which shows the process of inserting a fiber, an image fiber, and the tube for medium passages into a tube integrally, and an adhesive application process, (c) is a schematic sectional drawing which shows the heating process of a tube, (d) is It is a schematic sectional drawing which shows the state after extra length part grinding | polishing. (A) is a figure which shows the insertion process in the tube of a thin fiberscope, (b) is a schematic cross section which shows the state by which the front end side of each light guide fiber one end part and image fiber one end part was exposed from the tube FIG. 4C is a diagram showing a state after polishing of the extra length portion of the small diameter fiberscope. The figure which shows the peeling which arose in the objective lens and image fiber joint surface in the conventional small diameter fiberscope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thin fiberscope 2 Tube 3 Light guide fiber 3a, 4a One end part 4 Image fiber 4a1 Joint part 5 Objective lens 12, 41 Buffer layer 15 Adhesive 40 Medium passage tube

Claims (6)

A light guide fiber for transmitting irradiation light to irradiate an object; one end of the irradiation light irradiating side of the light guide fiber; and an optical component of an image fiber that is joined with an optical component to receive and propagate reflected light from the object in a state where one end portion is inserted into a hollow in the hollow outer part, a method for producing a thin fiberscope comprising fixed to the hollow shape exterior portion by adhesives,
A coating step of covering at least the periphery of the optical component joint in the image fiber with a first thermal stress absorbing buffer layer made of an elastic resin ;
The image fiber end portion including the optical component joint portion covered by the covering step and the irradiation light irradiation side one end portion of the light guide fiber are attached to the hollow exterior portion by an adhesive applied thereto. A manufacturing method of a thin fiberscope characterized by being fixed . Before Symbol coating process, the by dipping the image fiber end into a bath of elastic resin including an optical component by attaching the elastic resin around the end portion, the deposited elastic resin at one end around the image fiber 2. The method of manufacturing a thin fiberscope according to claim 1, further comprising a step of forming the first thermal stress absorbing buffer layer by curing. The small-diameter fiberscope includes a medium passage tube having one end inserted and fixed in the hollow exterior portion,
3. The method of manufacturing a thin fiberscope according to claim 1, further comprising a step of covering the periphery of the medium passage tube with a second heat stress absorbing buffer layer. A light guide fiber for transmitting irradiation light to irradiate an object; one end of the irradiation light irradiating side of the light guide fiber; and an optical component of an image fiber that is joined with an optical component to receive and propagate reflected light from the object in a state where one end portion is inserted into a hollow in the hollow outer part, a small diameter fiberscope comprising fixed to the hollow shape exterior portion by adhesives,
A first thermal stress absorbing buffer layer formed of an elastic resin and covering at least the periphery of the optical fiber joint of the image fiber ;
The image fiber end including the optical component joint covered with the first thermal stress absorbing buffer layer and the irradiation light irradiation side one end of the light guide fiber are formed into the hollow shape by the adhesive. A thin fiberscope characterized by being fixed to an exterior part .   5. The thin fiberscope according to claim 4, wherein the first thermal stress absorbing buffer layer covers the entire periphery of one end of the image fiber including the optical component. A medium passage tube having one end inserted and fixed in the hollow exterior portion;
A second heat stress absorbing buffer layer covering the medium passage tube;
The thin fiberscope according to claim 4 or 5, characterized by comprising: