JPH055530Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a fiberscope, and more particularly to a fiberscope useful for optically observing or measuring dark areas such as blood vessels and the inside of the heart.

<Prior Art> Conventionally, as shown in FIGS. 2 to 4, in order to optically observe the inside of a blood vessel or heart, a light source 3 is connected to an observation area 5 (a third In the figure, there are usually a plurality of light guides 9 that transmit illumination light to the inside of a blood vessel 7), and an image fiber 11 for image transmission, which has a lens 19 for imaging an observed object at its tip.
Then, in order to temporarily eliminate the blood flowing in front of the light guide 9 and the imaging lens 19 at the tip of the image fiber 11 in the observation area 5 to form a transparent area, physiological saline is introduced from the syringe 13. A fiberscope equipped with a liquid guide passage 15 is known. In this case, in order to form a region of transparent saline as described above, it is necessary to realize a flush 17 of physiological saline at the tip of the covering tube 1 with a flow rate comparable to the blood flow rate.
Note that the liquid guide passage 15 is not required to optically observe a region where no opaque liquid such as blood exists.

Next, the structure of the tip of a conventional fiberscope with a liquid guide passage will be explained with reference to FIGS. 5 to 8. Figure 7 is a longitudinal cross-sectional view of the tip, and Figure 5 is its A.
-A' line sectional view, Figure 6 is a B-B' line sectional view, Figure 8
The figure is a perspective view of the tip. In these figures, the recess (11th
At reference numeral 39) in the figure, there is an imaging adapter 2 that connects the imaging lens 19 and the tip of the image fiber 11.
3 is fixed with adhesive. Further, the outer surface of the tip molded portion 21 and the covering tube 1 are fixed with adhesive. The covering tube 1 is made of polyethylene resin, vinyl chloride resin, etc., and has an outer diameter of about 2.8 mm and an inner diameter of about 2.2 mm. Here, the outer surface of the tip molded part 21 and the covering tube 1 are bonded through the covering tube adhesion hole 25.
It is reinforced by filling it with an adhesive such as epoxy to cope with the impact during flashing. In this way, a flash flow 27 is formed as shown in FIG. In addition, in order to efficiently remove blood from the front surface of the imaging lens 19 and the light guide 9, the tip molded portion 21 is set back slightly by ΔL ₁ from the front surface of the covering tube 1, as shown in FIG.

Next, a method of manufacturing the tip molded portion 21 described above will be explained with reference to FIGS. 9 to 11. First, as shown in FIG. 9, a molding die 31 made of fluorine resin and having a through hole 29 with a diameter of 2 mm and a depth of about 10 mm is prepared.
A plastic fiber bundle 33 used as a light guide 9 for transmitting illumination light is inserted into the through hole 29, and a plastic fiber bundle 33 made of fluorocarbon resin or the like is inserted to form the recess (numeral 39 in FIG. 11) of the tip molded portion 21 described above. Insert the dummy tube 35. The gap between the through hole 29 of the mold 31 and the plastic fiber bundle 33 and dummy tube 35 is filled with a resin such as epoxy, and after hardening, one end surface is polished to form the molded part 37.
By removing the mold from the mold 31, a product as shown in FIG. 10 is obtained. Furthermore, dummy tube 35
By removing it from the resin molded part 37 and cutting a part, the tip molded part 21 having an end surface as shown in FIG. 11 and having a recess 39 is formed. FIG. 12 shows another example of the structure of a conventional fiberscope, in which the tip molded part 41 has a hole in the center for inserting and fixing an imaging adapter, has liquid guide passages 15 on the left and right sides, and has a plurality of holes. A light guide 9 for transmitting illumination light is embedded in an annular shape.

<Problems to be solved by the invention> By the way, the conventional fiberscope with the structure explained in FIGS. 2 to 12 has the following problems.
There was a problem.

Angle of view of fiberscope (α in Figure 13)
is determined by the focal length of the imaging lens and the outer diameter of the image fiber, and can exceed 100 degrees depending on the conditions, but approximately 70 degrees is common. However, even with light guides for illumination light transmission, when it is difficult to use a lens in front of the light guide, such as when the light guide is distributed annularly at the tip, such as when it is composed of an optical fiber bundle, it is difficult to The maximum aperture angle of light, that is, the illumination angle (β in FIG. 13) is determined by the NA (numerical aperture) of the light guide optical fiber and is relatively small. The numerical aperture is determined by the refractive index of the core and cladding, but for visible light transmission fibers such as plastic fibers, the numerical aperture is at most 0.6. Therefore, in water such as blood, which is the main field of use for fiberscopes, the illumination angle β is 50.
Limited to a degree. Therefore, as shown in FIG. 13, observation becomes impossible in a region 43 where the illumination angle β is less than the field angle α.

On the other hand, as can be seen from FIG. 8 and the like, conventional fiberscopes have sharp edges at their distal ends, which may cause damage to the inner walls of blood vessels, ureters, etc.

SUMMARY OF THE INVENTION In view of the problems of the prior art described above, an object of the present invention is to provide a fiberscope with an expanded illumination angle, a wide field of view, and a blunt tip.

<Means for solving the problems> The fiberscope of the present invention that achieves the above-mentioned purpose includes an image fiber for image transmission having an optical system for imaging an observed object at the tip, and an illumination light attached to this image fiber. In a fiberscope in which a transmission light guide is surrounded by a covered tube, the front surface of the fiberscope is covered with a substantially transparent resin body raised in a convex shape except for the front surface of the optical system for imaging an object to be observed. The front surface of the observation object imaging optical system is smoothly connected to the surface of the transparent resin body, and the surface of the transparent resin body has an illumination angle of illumination light emitted from the surface of the transparent resin body. is characterized in that it has a curvature that is larger than the field angle of the observation object imaging optical system.

<Function> The substantially transparent convex resin body on the front surface of the fiberscope expands the illumination angle of the light guide. Additionally, the convex resin body blunts the tip of the fiberscope.

<Example> An example of the present invention will be described with reference to FIG. 1 and FIGS. 14 to 22.

FIG. 1 is a perspective view of the tip of a fiberscope with a liquid guide passage. By dropping and hardening a substantially transparent resin except for the front surfaces of the imaging lens 19 and the liquid guide passage 15, the front surface of the fiberscope is is covered with a substantially transparent convex resin body 45 that extends to the peripheral edge of the tip of the covering tube 1 . As the resin, epoxy resin, ultraviolet curing silicone resin, acrylic resin, etc. are used.

FIG. 14 is a perspective view of the tip of a fiberscope without a liquid guide passage. The front surface of the guide is covered with a substantially transparent convex resin body 45 that extends to the peripheral edge of the tip of the covering tube 1.

As shown in FIGS. 1 and 14, when the front surface of the fiberscope is covered with a substantially transparent convex resin body 45,
Compared to the case without this (FIG. 13), the illumination angle β becomes larger as shown in FIG. 15, and the observation range becomes wider. Furthermore, as can be seen from FIGS. 1 and 14, the tip of the fiberscope is blunted, thereby reducing the risk of damaging soft tissues such as the inside of blood vessels and the ureter.

Next, with reference to FIGS. 16 to 19, an example of a method for forming a substantially transparent convex resin body will be described, taking as an example the case where the present invention is applied to the conventional fiberscope with a liquid guide passage shown in FIG. Explain.

First, to explain schematically with reference to FIG. 16, in order to prevent resin from adhering to the imaging lens 19, an appropriate amount of the imaging adapter 23 is protruded from the tip molding part and fixed with adhesive. A dummy tube 47 made of fluororesin or the like is inserted into the liquid guide passage to prevent clogging by resin. Thereafter, a suitable substantially transparent resin 49 is dropped from above. Then, since the resin 49 has an appropriate viscosity, a convex bulge is formed around the tip of the imaging adapter 23 and the side surface of the dummy tube 47. Furthermore, the surface of the bulge is smooth due to the surface tension of the resin. Therefore, by removing the dummy tube 47 after the resin has hardened, the front surface of the fiberscope, except for the imaging lens 19 and the flash liquid guide passage, is covered with a convex, smooth, and substantially transparent resin body. In addition, when dropping the resin, it is preferable to do as follows. First, as shown in Fig. 17, a mold 5 made of fluorine resin, etc.
Insert the tip of the fiberscope into 1, buff the front surface (excluding the imaging adapter), and then insert the tip from the resin mold 51 to ΔL ₂ =
Lower the imaging adapter 23 by about 0.2mm, and lower it to ΔL ₃ = 0.3.
The dummy tube 47 is inserted while protruding by approximately 1 mm, and then substantially transparent resin 49 is dropped into the resin mold 51 with the tip of the fiberscope inserted into the resin mold 51, as shown in FIG. Buffing improves the adhesion between the resin 49, the molded end portion 41, and the covering tube 1, and reduces the transmission loss of illumination light. Further, by lowering the tip of the fiberscope by ΔL ₂ , it is possible to prevent the resin 49 from flowing out to the periphery, and the connection between the peripheral edge of the covering tube 1 and the convex resin body 45 becomes extremely smooth. In addition, the imaging adapter 2
The amount of protrusion ΔZ of the convex resin body 45 can be adjusted by the protrusion of ΔL ₃ of No. 3.

Here, the relationship between the protrusion amount ΔZ of the convex resin body 45 and the irradiation angle β will be explained with reference to FIGS. 20 to 22. In FIGS. 20 and 21, 53 is a fiberscope having a convex portion 55 at its tip;
Its diameter is D, the refractive index of the convex resin 45 is _nL , the numerical aperture of the light guide is NA, the radius of curvature of the convex part is R, the amount of protrusion of the convex part is ΔZ, the optical axis is Z, the center O and the convex part The angle between the line OQ connecting point Q on the periphery and the optical axis Z is γ ₀ , and the line connecting point P on the convex surface and center O
The angle between the OP and the optical axis Z is γ, θ=sin ^-1 (NA/n _L ), the refractive index of the outside (water, etc.) is mw, and the light that forms an angle of θ with the optical axis is refracted at the convex surface. Let the angles between the emitted light and the optical axis be β ₁ and β ₂ when the emitted light is emitted.

(i) First, considering the case of Oγ<θ shown in Fig. 20, n _W sin (β ₁ − γ) = n _L sin (θ − γ) n _W sin (β ₂ + γ) = n _L sin (θ + γ ), so β ₁ = sin ^-1 {n _L /n _W sin(θ−γ)}+γ ...Equation (1) β ₂ = sin ^-1 {n _L /n _W sin(θ+γ)}−γ ...Equation (2) is obtained.

(ii) Next, considering the case of θ<γγ ₀ shown in Figure 21, n _W sin (γ − β ₁ ) = n _L sin (γ − θ) n _W sin (β ₂ + γ) = n _L sin (θ+γ), so β ₁ = γ−sin ^-1 {n _L /n _W sin(γ−θ)} ...(3) β ₂ = sin ^-1 {n _L /n _W sin(θ+γ)} −γ ...Equation (4) is obtained.

From equations (1) to (4), β ₁ < β ₂ and the maximum value of β ₂ is considered to be β ₂ = sin ^-1 {n _L /n _W sin (θ + γ ₀ )} − γ ₀ Therefore, the illumination angle β is θ=sin ^-1
Considering (NA/n _L ), β=2sin ^-1 [n _L /n _W sin{sin ^-1 (NA/n _L )+γ ₀ }]
−2γ ₀
...is given by equation (5). By the way, since γ ₀ = sin ^-1 (D/2R) and ΔZ = R (1-cos γ ₀ ), the desired illumination angle β
Once ΔZ is determined, the required protrusion amount ΔZ is determined from n _L , n _W , NA, and D.

Now, as a general case, n _L = 1.49, n _W =
1.33 and NA=0.47, equation (5) becomes a graph as shown in Figure 22. Therefore, if β = 60°, then γ ₀ = 37°, so
If D=1.7mm, R=1.7/2sin37°=1.4mm ∴ΔZ=1.4(1−cos37°)=0.28mm.

Also, if β = 70°, γ ₀ = 42°, so if D = 1.7mm, R = 1.7/2sin42° = 1.3mm ∴ΔZ = 1.3 (1-cos42°) = 0.33mm becomes.

<Effects of the Invention> According to the invention, since the front surface of the fiberscope is covered with a substantially transparent convex resin body, the illumination angle is expanded, and the field of view of the fiberscope is thus widened. Furthermore, the presence of the convex resin body blunts the tip of the fiberscope, reducing the risk of damaging the object to be observed. Further, since the convex resin body can be realized by a simple process of dropping a substantially transparent resin and curing it, the cost is reduced compared to the case where a lens is used. Further, when a plastic fiber is used as a light guide for transmitting illumination light, the end face of the plastic fiber is protected by a convex resin body. Furthermore, the convex resin body uniformizes the illuminance of the object to be observed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the tip of a fiberscope with a liquid guide passage according to an embodiment of the present invention. Figures 2 to 13 are diagrams explaining conventional fiberscopes. Figure 2 is a configuration diagram of the fiberscope system, Figure 3 is a perspective view of the tip of the fiberscope inserted into the observation target area, and Figure 3 is a perspective view of the fiberscope tip inserted into the observation target area. Figure 4 is a sectional view of the blood vessel insertion part, Figure 5 is a sectional view taken along line A-A' in Figure 7, and Figure 6 is a sectional view taken along line B in Figure 7.
-B' line sectional view, Figure 7 is a longitudinal sectional view of the tip of the fiberscope, Figure 8 is a perspective view of the tip,
Figures 9 to 11 are explanatory diagrams of the manufacturing method of the tip molded part, Figure 12 is a perspective view showing another example of the conventional fiberscope tip, and Figure 13 is the illumination angle of the conventional fiberscope tip. FIG. 3 is an explanatory diagram of the relationship between and the angle of view. FIG. 14 is a perspective view of the distal end of a fiberscope without a liquid guide passage according to another embodiment of the present invention. FIG. 15 is an explanatory diagram of the relationship between the illumination angle and the field angle of the fiberscope tip according to the present invention.
FIGS. 16 to 19 are explanatory diagrams of an example of a method of forming a substantially transparent convex resin body according to the present invention. Figures 20 and 21 are explanatory diagrams of illumination angle expansion, and Figure 22
The figure is a graph of the relational expression. In the drawing, 1 is a covered tube, 3 is a light source, 5 is an observation area, 7 is a blood vessel, 9 is a light guide for transmitting illumination light, 11 is an image fiber for transmitting an image, 13 is a syringe, 15 is a liquid guide passage, and 17 is a Flash, 19 is an imaging lens, 21 and 41 are tip molding parts, 23 is an imaging adapter, 27 is a flash flow,
31 is a mold for molding, 35 is a dummy tube for a recess, 39 is a recess, 45 is a substantially transparent convex resin body, 4
7 is a dummy tube for flash flow, 49 is a substantially transparent resin, and 51 is a mold for the resin body.

Claims (1)

[Claims for Utility Model Registration] (1) An image fiber for image transmission having an optical system for imaging an object at its tip and a light guide for transmitting illumination light attached to this image fiber are surrounded by a covered tube. In the fiberscope, the front surface of the fiberscope is covered with a substantially transparent resin body raised in a convex shape except for the front surface of the optical system for imaging an object to be observed, and the optical system for imaging an object to be observed is covered with a substantially transparent resin body. The front surface is smoothly connected to the surface of the transparent resin body, and the illumination angle of the illumination light emitted from the surface of the transparent resin body is the angle of view of the observation object imaging optical system. A fiberscope characterized in that it has a curvature greater than . (2) In claim 1 of the utility model registration claim, a flash flow of transparent liquid is formed in front of the optical system and light guide between the inner wall of the covered tube and the outer surface of the image fiber and light guide. A fiberscope characterized in that a liquid guide path is formed for the purpose of (3) Utility Model Registration The fiberscope according to claim 1, characterized in that the resin body is an epoxy resin, an ultraviolet curable silicone resin, or an acrylic resin.