JPH07204158A - Endoscope - Google Patents

Abstract

PURPOSE:To provide an endoscope improved in the distribution of light in all visual fields and having an illumination optical system with high illumination efficiency. CONSTITUTION:This endoscope is provided with the illumination optical system 8 to radiate the light to observe the celom of an examinee, and an objective optical system 9 to form image by condensing the light reflected from an observation part irradiated with the light. For the lens system of the illumination optical system 8, a lens or glass of refractive index distribution type in which different kinds of refractive indexes are distributed in the inside is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an optical system of an endoscope, and more particularly, to a uniform and wide-angle light distribution by using a gradient index lens or a glass material as a lens system of an illumination optical system. The present invention relates to an endoscope having an optical system with improved light distribution characteristics.

[0002]

2. Description of the Related Art Endoscope devices include fiberscope type and electronic endoscopes, which will be briefly described with reference to FIG. In FIG. 8, the endoscope device includes a monitor 1 for displaying an endoscopic image, a device body 2 including an operation control switch, and a scope 3 used by being inserted into a body cavity of a subject.
And. At the tip of the flexible tube 4 which is the insertion portion of the scope 3, a rigid portion 5 equipped with an optical system including a CCD camera, a forceps hole, a cleaning nozzle and the like is provided. On the other hand, on the proximal end side of the flexible tube 4, an operation unit 6 for performing an angle operation or the like which is a bending operation of the flexible tube 4 of the scope 3.
And a universal cord 7 for transmitting a video camera signal to the device body 2. Although not shown, inside the flexible tube 4, a light guide fiber bundle, an air supply tube, a water supply tube, a cable for wiring, and the like are incorporated. The rigid portion 5 is usually composed of two illumination optical systems 8, one objective optical system 9, a forceps hole 10, an air supply hole 11A and a water supply hole 11B.

FIG. 9A is a front view of the rigid portion 5 seen from the front side, and FIG. 9B is a sectional view of the optical system portion taken along the line L1. In FIG. 9, the optical system of the endoscope is composed of two illumination optical systems 8 and one objective optical system 9. In addition to this, the rigid portion 5 has a forceps hole 10 and two air supply / water supply units. It is equipped with a hole 11. Each of the illumination optical systems 8 has a plano-concave lens 12 and a light guide fiber bundle 13 for supplying light to the plano-concave lens 12, and the objective optical system 9 has a convex lens for condensing and the collected light. It includes a CCD camera and the like for forming an image from C, and C is located behind the objective optical system 9.
A wiring cable 14 for transmitting the output of the CD camera to the apparatus main body 2 is provided.

When observing the inside of a body cavity of a subject with such an optical system of an endoscope, the light supplied from the light guide fiber bundle 13 is incident on the plano-concave lens 12 at the curved surface 1.
The light enters from 2A, is refracted by the plano-concave lens 12, is emitted, and is distributed to illuminate the observation site. The reflected light from the observation site is collected by the objective optical system 9, and the collected light is imaged by a CCD camera or the like. In this case, the incident curved surface 12
Center 12B of A, that is, light guide fiber bundle 1
If the central axis of 3 and the center 12C of the exit surface of the plano-concave lens 12 are arranged so as to coincide with each other, the light emitted from the illumination optical system 8 may be too intense at the central portion of the visual field and the peripheral portion may be dark. Therefore, conventionally, as shown in FIG. 9, the center 12C of the exit surface is set to the incident curved surface 1 in order to uniformly distribute the light.
The center 12B of 2A is decentered by d in the direction opposite to the center D of the objective optical system 9 (the direction away from the objective optical system 9).

[0005]

However, in the conventional optical system of the endoscope of this type, since the light beam is blocked by the side surface of the plano-concave lens 12 of the illumination optical system, the loss of light is large and the illumination efficiency is poor. There is a drawback that Further, even if the light distribution in the direction of the straight line (the line L1 in FIG. 9) connecting the illumination optical system and the objective optical system is improved, the light distribution is made in the straight line direction perpendicular to this straight line and orthogonal to the axis of the light guide fiber bundle. There is a problem that the brightness is insufficient because it does not change or becomes narrow.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an endoscope having an illumination optical system with improved light distribution characteristics and improved illumination efficiency in the entire visual field. is there.

[0007]

In order to achieve the above object, the present invention has improved the light distribution characteristics by making the configuration of the endoscope as follows. That is, it has an illumination optical system for irradiating light for observing the inside of the body cavity of the subject and an objective optical system for condensing and forming an image of the light reflected from the observation site irradiated with the light. In the endoscope, the lens system of the illumination optical system is characterized by using a gradient index lens or glass material having different refractive indices distributed therein.

[0008]

According to the above arrangement, since the gradient index lens or glass material is used for the lens system of the illumination optical system, the light guide fiber is perpendicular to the straight line connecting the illumination optical system and the objective optical system. The light distribution can be spread in a direction orthogonal to the bundle axis, and the light distribution characteristics in the entire visual field illuminated by the illumination optical system are improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same components as those described in the related art are designated by the same reference numerals. FIG. 1 is a diagram for explaining an optical system of an endoscope of the present invention, which is basically the same as FIG. 9 (a). Therefore,
In FIG. 1, two illumination optical systems 8 for irradiating light for observing the inside of a body cavity of a subject, and a convex lens for collecting light reflected from an observation site irradiated with light are collected. One objective optical system 9 including a CCD camera for forming an image from the emitted light, and the centers C and D of the exit surface of each optical system are shown. Then, a linear direction connecting the illumination optical system and the objective optical system, that is, a line L1 connecting the two centers C and D and a direction perpendicular to the line and orthogonal to the axis 13B of the light guide fiber bundle 13 (see FIG. 9). A line L2 representing is shown.
In each of the following examples, the line L1 is used to explain the configuration of the optical system.
And a sectional view taken along line L2. The term "illumination optical system" as used herein means a light guide fiber bundle, a lens, a glass material, a filter, and the like, which also includes the light guide fiber bundle. When the term "lens system" is used, the light guide fiber bundle is included. It means a combination of lens and glass excluding filters and filters.

FIG. 2 is a diagram showing a first embodiment of the optical system of the endoscope of the present invention. 2A is a sectional view taken along the line L1, and FIG. 2B is a sectional view taken along the line L2. 2C, 2D, and 2E are views showing the refractive index distribution of the lens system. 2 (a) and 2 (b), this optical system includes a plano-concave lens 15, a glass material 16 having an exit end surface inclined to the incident surface side of the plano-concave lens 15, and the glass material 1.
It is composed of two illumination optical systems 8 each having a light guide fiber bundle 13 for supplying a light beam via 6, and one objective optical system 9 arranged therebetween. The plano-concave lens 15 does not have a uniform internal refractive index, but different refractive indexes are distributed. Such a lens will be referred to as a gradient index lens. The plano-concave lens 15 uses a gradient index lens, and in the direction of the line L1,
The refractive index of the plano-concave lens 15h is, as shown in FIG.
As shown in FIG. 2D, the plano-concave lens 15m has a center 15B of the incident curved surface portion 15A of the plano-concave lens 15 as shown in FIG.
It becomes larger in the direction away from (line 15B). In this case, assuming that the refractive index of air is 1, the magnitude relationship between the refractive indices is 1.
<N3 <n2 <n1. Further, in the direction of the line L2, the refractive index of the plano-concave lens 15h increases in the direction away from the center of the incident curved surface portion 15A of the lens as shown in FIG. 2 (e). In this case, since the optical axis 13B of the light guide fiber bundle 13 is slightly shifted from the center 15B of the incident curved surface portion 15A of the lens to the objective optical system 9 side, the magnitude relation of the refractive index is 1 <n3 <n5 <n4 <n1. Has become. The same applies to the plano-concave lens 15m. Then, the glass material 16 is inclined so that its exit end face becomes higher in the direction away from the objective optical system 9. Therefore, the optical axis 16C of the exit end face of the glass material 16 is
As shown in FIG. 2A, when viewed from the direction of the line L1, it is tilted in the direction of the objective optical system 9 by the angle φ. The optical axes 15C of the exit end surfaces of the plano-concave lenses 15h and 15m are also shifted from the central axis 13B of the light guide fiber bundle 13 to the side away from the objective optical system 9.

FIG. 3 is a diagram for explaining the structure of a gradient index plano-concave lens, and FIG. 3 (a) shows a perspective view of the lens and a three-dimensional structure of its refractive index distribution. b)
Shows the contour distribution of the refractive index when this lens is viewed from above. The curve P1 in FIG. 3A is the plano-concave lens 15h.
The curve P2 of the refractive index of the outer peripheral portion of the curve shows the refractive index of the outer periphery 15A-a of the incident curved surface portion 15A of the plano-concave lens 15h. It can be seen that the refractive index n3 at the center 15B of the incident curved surface portion 15A of the plano-concave lens 15h is the smallest. The thin circle in FIG. 3B indicates the contour line of the refractive index, and the circle P1 is the refractive index of the outer peripheral portion of the plano-concave lens 15h, and the circle P.
Reference numeral 2 indicates the refractive index of the outer circumference 15A-a of the incident curved surface portion 15A, and point n3 indicates the refractive index at the center 15B of the incident curved surface portion 15A.

By using such an illumination optical system 8, a light distribution as shown in FIG. 4 can be obtained. As a result,
It has the effect shown in. FIG. 4A is a diagram for explaining light distribution in the line L1 direction, and FIG. 4B is a diagram for explaining light distribution in the line L2 direction. FIG. 5A is the direction of line L1 and FIG.
FIG. 6 is a diagram showing a light distribution characteristic in a direction of a line L2. Figure 4
In (a), the light guide fiber bundle 13
A light ray that enters the plano-concave lens 15h from h through the glass material 16h passes through the plano-concave lens 15h and is emitted as a light ray R. The light ray R-b is a light ray emitted to the objective optical system 9 side, the light ray R-a is a ray farthest from the objective optical system 9, and the light ray R-s is a ray emitted at a right angle to the exit end face of the plano-concave lens 15h. , Can be generally expressed as a ray R-i.
The feature of this embodiment is that by using the plano-concave lens 15h having a gradient index structure and the inclined glass material 16h,
-s is shifted from the center 15B (line 15B) of the incident curved surface portion toward the objective optical system 9 side. With such a configuration, the light distribution characteristic as shown in FIG. The light distribution characteristic shown by the broken line in FIG. 5A is a conventional one, and is a case where the light ray R-s coincides with the line 15B. On the other hand, what is shown by the solid line is the light distribution characteristic obtained by this embodiment, and the illuminance becomes larger in the direction away from the objective optical system 9 than the conventional one, and as a result, the light distribution in the direction of the line L1. The characteristics are more uniform. The reason is that a ray on the ray R-b side of the ray R-s is emitted to the objective optical system 9 side, and a ray on the ray R-a side of the ray R-s is emitted in a direction away from the objective optical system 9. , FIG. 4 (a)
As you can see, the light guide fiber bundle 1
This is because the light ray emitted from 3h is used more in the latter direction (left side of the line S). Therefore, in this embodiment, the glass material 1 is used to obtain appropriate light distribution characteristics.
The light ray R-s may be determined from the exit angle from 6h and the refractive index distribution of the plano-concave lens 15h. This is set as follows. The light beam emitted from the glass material 16h is a plano-concave lens 1.
The light is refracted at the incident curved surface portion 15A for 5 h. At this time Snell
Since the law of (Snell) is followed, assuming that the refractive index of the incident position of the ray R is n (xi, yi), the incident angle Φ, and the outgoing angle Φ ′, in general, 1 * Sin Φ = n (xi, yi ) ＊ Sin Φ ′ Here, 1 indicates the refractive index of air, and n (x
i, yi) indicates the refractive index at the light incident position (xi, yi) of the gradient index lens 15h having a different refractive index depending on the position. If the angle formed by the light beam emitted from the glass material 16h with the optical axis direction 13B (that is, the line 15B) of the light guide fiber bundle 13h is α and the angle formed by the light beam R-s and the normal line is θs, the light beam R-s is obtained. The required conditions can be expressed by the following equation. 1 * Sin (.theta.s + .alpha.) = N (xs, ys) * Sin .theta.s From this equation, when the ray R-s is obtained, the ray R-b that is incident from the objective optical system 9 side in the ray R is converted by the plano-concave lens 15h. The light is refracted without being blocked by the side surface and emitted at an emission angle θb. Further, the light ray R-a incident from the opposite side of the objective optical system 9 is refracted by the plano-concave lens 15h without being blocked by its side surface and is emitted at the emission angle θa. Plano-concave lens 1
Since the refractive index distribution of 5h is as described above, the emission angle θb can be made small and the emission angle θa can be made large, and this is the same on the plano-concave lens 15m side.

Further, in the direction of line L2, FIG.
As shown in, the light ray R is emitted symmetrically with respect to the optical axis 13B, but it can be refracted by the plano-concave lens 15h without being blocked by its side surface to increase the emission angle,
This is the same on the side of the plano-concave lens 15m, so that the light distribution in this direction can be widened. As a result, the light distribution characteristic as shown in FIG. Figure 5
The light distribution characteristics shown by the broken line in (b) are conventional ones, and those shown by the solid line are those obtained by this embodiment. From FIG. 5 (b), it can be seen that the illuminance increases as the distance from the optical axis 13B increases as compared with the conventional one.

From these, it is possible to improve the light distribution characteristic in the entire visual field and to widen the light distribution to the peripheral portion of the visual field without wasting the light rays as in the conventional case. Figure 6
Shows a second embodiment of the optical system of the endoscope of the present invention. FIG. 6A is a sectional view taken along the line L1.
(B) is a sectional view taken along the line L2. Also,
6C, 6D, and 6E are diagrams showing the refractive index distribution of the lens system. 6 (a) and 6
In (b), this optical system is a two-illumination optical system having a light guide fiber bundle 13 for supplying light rays, a plano-concave lens 15, and a glass material 17 having an exit surface inclined to the exit end surface of the plano-concave lens 15. 8 and one objective optical system 9 arranged between them, and the glass material 17 and the objective optical system 9 for preventing water droplets from accumulating in the objective optical system 9 and its periphery because the exit surface of the glass material 17 is inclined. The protective glass 18 is provided so as to cover the system 9. The glass material 17 is inclined so that its exit surface becomes higher in the direction away from the objective optical system 9. Therefore, the optical axis 17C of the exit surface of the glass material 17 is
As shown in FIG. 6 (a), when viewed from the direction of the line L1, it is inclined by the angle ψ toward the objective optical system 9. Further, in this embodiment, the central axis 1 of the light guide fiber bundle 13 is
3B and the center 15B of the incident curved surface portion of the plano-concave lens 15 (see FIG. 2).
Line 15B) in FIG. There are two types of implementations of this example.

(I) One is the case where the plano-concave lenses 15h and 15m are gradient index lenses and the glass materials 17h and 17m having a uniform refractive index (refractive index n6) are used. In this case, the refractive index of the plano-concave lens 15 in the direction of the line L1 is as shown in FIG. 6 (c) for 15h and for the incident curved surface portion 15A of the plano-concave lens 15 as shown in FIG. 6 (d). It increases in the direction away from the center 15B (line 13B). In this case, assuming that the refractive index of air is 1, the magnitude relationship of the refractive indices is 1 <n6 ≦ n3 <
n2 <n1. Further, in the direction of the line L2, 15
As shown in FIG. 6E, the refractive index of h increases in the direction away from the center 15B of the incident curved surface portion 15A of the lens. In this case, the magnitude relation of the refractive index is 1 <n6 ≤n3
<N7 <n1. The same applies to the plano-concave lens 15m. The protective glass 18 has a refractive index smaller than the refractive index n6 of the glass material 17.

(Ii) In the other, plano-concave lenses 15'h and 15'm having a uniform refractive index (refractive index n8) are used, and the glass materials 17'h and 17'm are of a refractive index distribution type. This is the case when it is a glass material. In this case, glass material 1
When the refractive index of 7'is in the direction of the line L1, 17'h is as shown in FIG. 6C, and 17'm is as shown in FIG. 6D, the incident curved surface portion 15 of the plano-concave lens 15 '. It becomes larger in the direction away from the center 15'B (line 13B) of'A. In this case, when the refractive index of air is 1, the magnitude relationship of the refractive indexes is 1 <n3 <n2 <n1 ≦ n8. Also, the line L
In the two directions, as shown in FIG. 6 (e), the refractive index of 17'h is the center 15'B of the incident curved surface portion 15'A of the lens.
It is getting larger in the direction away from. In this case, the magnitude relationship of the refractive indexes is 1 <n3 <n7 <n1 ≦ n8. This also applies to the glass material 17'm. The protective glass 18 has a refractive index smaller than the refractive index n3 of the glass material 17 '.

By making the structure of the optical system as described above, the same effect as shown in FIG. 5 can be obtained as in the first embodiment shown in FIG. In this embodiment, the glass material 17 having an inclination is used as an example.
When the glass material 17 'of (ii) is of the gradient index type, it need not be inclined. Also, the glass material 17 'of (ii)
Is a refractive index distribution type, by appropriately setting the conditions, a plano-convex lens having a uniform refractive index can be used instead of the plano-concave lens 15 '. Further, in this embodiment, a concave lens in which the plano-concave lens 15 and the glass material 17 are integrated may be used. That is, this concave lens may have the same incident surface as the plano-concave lens 15 and an exit surface having the same refractive index and inclination as the glass 17.

FIG. 7 shows a third embodiment of the optical system of the endoscope of the present invention. The basic structure of this embodiment is the same as that shown in FIG. 2 or FIG. 6, but the plano-concave lens 1 therein is used.
5 (including the case of 15 ', but omit 15' below)
The difference is that the shape of the incident curved surface portion 15A is changed to an aspherical surface. 7A and 7B show the line L1.
FIG. 7 is a diagram showing a sectional view and a curvature characteristic in FIG.
(C) is a figure which shows the cutting surface figure and curvature characteristic in the line L2. As shown in FIGS. 7A to 7C,
The incident curved surface portion 15A of the plano-concave lens 15 has a different curvature C1.
, C2, C3. Incident curved surface part 1
It is shown that the vicinity of the center 15B (line 15B) of 5A is C1 having the largest curvature, and C2 and C3 having the smaller curvature intermittently with increasing distance from it. In this case, the incident curved surface portion 15A is manufactured by gradually cutting from C3 to C1. Further, the incident curved surface portion 15A of the plano-concave lens 15 is shown in FIG.
Instead of the curvature characteristics as shown in (a) to FIG. 7 (c),
As shown in FIG. 7D, the center 15B of the incident curved surface portion 15A
The curvature characteristics may be such that the curvature is small from the vicinity of to the periphery and becomes a continuous curved surface.

By making the incident curved surface portion 15A of the plano-concave lens 15 into such a shape, the light beam supplied from the light guide fiber bundle 13 is projected.
Those incident from the vicinity of the center 15B of the incident curved surface portion 15A are refracted more largely, and those incident from the peripheral portion are refracted slightly and exit. Therefore, the difference in brightness between the central portion and the peripheral portion of the visual field is further reduced, and the light distribution characteristic is improved.

In each of the above-described embodiments, the example in which one plano-concave lens is used for the lens system of the illumination optical system 8 has been described, but the present invention is not limited to this, and a plurality of lenses may be used in combination. Good. Further, the refractive index distribution type plano-concave lens and the glass material are not linear in refractive index distribution characteristics as shown in each embodiment, and similar effects can be obtained even if they have nonlinear or intermittent distribution characteristics.

[0021]

As described above, according to the endoscope of the present invention, since the gradient index lens or the glass material is used for the lens system of the illumination optical system, the field of view is reduced without lowering the illumination efficiency. It is possible to improve the light distribution characteristics in the entire visual field by reducing the difference in brightness between the peripheral part and the central part and making it uniform. As a result, the time required for observation and diagnosis is shortened, the accuracy of diagnosis is improved, and the reliability of the apparatus is improved. Further, since the peripheral part of the visual field can be made bright without increasing the thickness of the scope, it becomes possible to easily perform the observation and diagnosis without increasing the pain to the patient.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an optical system of an endoscope of the present invention.

FIG. 2 is a diagram showing a first embodiment of the optical system of the endoscope of the present invention.

FIG. 3 is a diagram for explaining the structure of a plano-concave lens of gradient index distribution type.

FIG. 4 is a diagram for explaining light distribution obtained according to the first embodiment.

FIG. 5 is a diagram for explaining a light distribution characteristic obtained by the first embodiment.

FIG. 6 is a diagram showing a second embodiment of the optical system of the endoscope of the present invention.

FIG. 7 is a diagram showing a third embodiment of the optical system of the endoscope of the present invention.

FIG. 8 is a diagram for explaining the outline of the endoscope apparatus.

FIG. 9 is a diagram for explaining a conventional technique.

[Explanation of symbols]

 1 monitor 2 device body 3 scope 4 flexible tube 5 rigid part 6 operation part 7 universal code 8 illumination optical system 9 objective optical system 10 forceps hole 11 air supply / water supply hole 12 plano-concave lens 13 light guide fiber bundle 14 wiring cable 15 flat Concave lens 16 Glass material 17 Glass material 18 Protective glass

Claims (6)

[Claims] 1. An illumination optical system for irradiating light for observing the inside of a body cavity of a subject, and an objective optical system for condensing and forming an image of light reflected from an observation site irradiated with light. In the endoscope having the above, an index distribution type lens or glass material having different refractive indexes distributed therein is used in the lens system of the illumination optical system. 2. The refraction index of the plano-concave lens according to claim 1, wherein the lens system of the illumination optical system includes a plano-concave lens with a distributed refractive index and a glass material having an inclined exit end face on the incident surface side of the plano-concave lens. The ratio is large in the direction away from the center of the incident curved surface part of the plano-concave lens in the direction of the straight line connecting the illumination optical system and the objective optical system, and the plano-concave lens is also perpendicular to this line and perpendicular to the axis of the light guide fiber bundle. The endoscope is characterized in that it becomes larger in the direction away from the center of the incident curved surface part of. 3. The illumination optical system lens system according to claim 1, wherein the lens system of the illumination optical system has a plano-concave lens and a glass material on the exit end face side of the plano-concave lens, and at least one of the plano-concave lens and the glass material is of a refractive index distribution type. The refractive index is large in the straight line connecting the illumination optical system and the objective optical system in the direction away from the center of the incident curved surface portion of the plano-concave lens, and is also perpendicular to this straight line and orthogonal to the axis of the light guide fiber bundle. The endoscope is also characterized in that it is larger in the direction away from the center of the incident curved surface portion. 4. The endoscope according to claim 3, wherein the exit surface of the glass material is inclined so that its height becomes higher in the direction away from the objective optical system. 5. The endoscope according to claim 3, wherein when the glass material is of a gradient index type, a plano-convex lens having a uniform refractive index is used instead of the plano-concave lens. 6. The endoscope according to claim 2 or 3, wherein the light incident curved surface portion of the plano-concave lens is an aspherical surface, and the central portion has a larger curvature than the peripheral portion.