JP3049524B2 - Endoscope objective optical system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective optical system for an endoscope having a small outer diameter, such as a urinary organ, and an endoscope end assembly holding the objective optical system.

[0002]

2. Description of the Related Art In an endoscope such as a urinary tract, for example, when calculus in a ureter is crushed by a calculus breaking device or a treatment tool such as a laser, there is a strong demand for observing the treatment tool mainly in a visual field. However, when the calculus is brought close to the center of the visual field in the direct-view objective optical system, the treatment tool cannot be brought to the center of the visual field due to parallax between the objective optical system and the channel through which the treatment tool passes. Therefore, there is a need to make the objective optical system oblique.

Conventional examples of the oblique objective optical system are disclosed in Japanese Patent Application Laid-Open No. 63-269112 and German Utility Model Registration No. 900.
Japanese Patent Application Laid-Open No. 2-665 discloses an optical system in which a deflection prism is used for an objective optical system, such as the optical system described in Japanese Patent No.
There is known an optical system described in Japanese Patent Application Publication No. 11-115, in which a field mask is decentered.

[0004]

SUMMARY OF THE INVENTION For example, Japanese Patent Application Laid-Open No.
A conventional example of Japanese Patent Application Laid-Open No. 3-269112 has a configuration shown in FIG. 13 and includes a deflection prism having a wedge surface in order from the object side, a wedge-shaped spacer, two convex lenses, and an image guide. When an optical system having such a configuration is used for an endoscope having a small outer diameter, the outer diameter of the prism becomes small, and therefore, the workability of the prism is very poor. Further, in the case of a perspective optical system, it is necessary to deviate the illumination optical system in accordance with the oblique angle and the oblique direction of the objective optical system, and furthermore, it is necessary to make the deflective directions of the objective optical system and the illumination optical system coincide. There is also a problem that it is very difficult to match the directions of the two declination directions and the assemblability is poor.

An optical system using a deflection prism is shown in FIG.
In the case where the wedge surface is provided on the first surface as shown in FIG. 4, in addition to the problem pointed out in Japanese Patent Application Laid-Open No. 63-269112, there is a danger that the affected part may be inadvertently damaged during insertion. ing.

In addition, when a perspective is achieved by eccentricity of a field mask as disclosed in Japanese Patent Application Laid-Open No. 2-66511, it is very difficult to adjust the direction of the perspective and the eccentricity of the mask increases the imaging surface. Therefore, there is a problem that the outer diameter of the endoscope becomes large as a result.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an objective optical system for a perspective endoscope which is easy to process and assemble, and an endoscope end assembly holding the objective optical system. The purpose is.

[0008]

The objective optical system according to the present invention comprises:
A first group consisting of a lens having a positive power and a lens group having a positive power and a second group consisting of a lens having a positive power are arranged in order from the object side. The optical axis of the first group and the optical axis of the second group are It is decentered to provide an endoscope objective optical system for oblique viewing.

Next, the principle of the present invention will be described with reference to the drawings. FIG. 6 is a diagram showing a basic configuration of the present invention, in which a first group and a second group are shown.
The group is eccentric by δ. FIG. 7 is a diagram showing the relationship between the image height h and the angle θ ′ when the principal ray is incident on the imaging surface in the objective optical system having the basic configuration of the present invention.
First, considering the case of direct viewing with an objective optical system without eccentricity as shown in FIG. 8, the following relational expression (a) holds between the half angle of view ω and the image height h. ω = (180 / f · π) × 1.05h (a) where f is the focal length of the objective optical system.

As shown in FIG. 6, when the angle at which the optical axis of the entire system is incident on the imaging plane is inclined by θ ′, the angle at which the principal ray is incident on the image plane becomes
As shown in FIG. 7, the angle of the non-eccentric optical system shown in FIG.
) Is uniformly shifted. Normally, it is considered that the angle at which the principal ray is incident on the image plane is allowed to be up to about 15 °, so it is desirable that the eccentricity δ satisfies the condition that θ ′ is 15 ° or less. Here, between the principal ray incident angle θ ′ and the amount of eccentricity δ, a relationship substantially expressed by the following equation (b) is established. δ / f = n sin θ ′ (b) where n is the refractive index of the medium immediately before the image plane.

From the equations (a) and (b), the incident angle θ 'is represented by the following equation (c). θ ′ = sin ⁻¹ (δ · ω · π / n × 180 × 1.05 × h) (c) Here, as described above, the incident angle θ ′ is 15 ° or less, that is, 0 <θ ′ < Considering that it is desirable to satisfy Condition 15, the following condition (1) needs to be satisfied. (1) 0 <δ · ω / h <30 For the above reasons, in the objective optical system having the above-described configuration, if the first and second groups are decentered so as to satisfy the condition (1), the principal ray is obtained. A good perspective can also be achieved for the incident angle.

By eccentricity and eccentricity satisfying the conditions as in the above-described configuration of the present invention, a perspective view can be realized without using a deflection prism.

Since the deflection prism is not required, a wedge-shaped space is not required. The eccentricity of the lens is
Since the hole position of the lens frame is merely decentered, the frame structure is simplified, for example, as specifically described later. Therefore, it is possible to use the same assembling method as in the direct view, and it is not necessary to adjust the direction in which the squinting is desired. Also, if the illumination optical system is decentered in the oblique direction by using the same means, it is not necessary to align the axes of the objective optical system and the illumination optical system.

With the basic structure of the present invention, the problems of the conventional workability and assemblability can be solved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the endoscope optical system of the present invention described above will be described. Example 1 f = 1.000, F-number = 1.780, 2ω = 85.8 °, image height = 0.7067 Oblique angle θ = 9.3 ° r ₁ = ∞ d ₁ = 0.6007 n ₁ = 1.883 ν ₁ = 40.78 r ₂ = ∞ (stop) d ₂ = 1.4134 n ₂ = 1.883 ν ₂ = 40.78 r ₃ = -1.3428 d ₃ = 0.3534 r ₄ = 1.9788 d ₄ = 1.488 n ₃ = 1.883 ν ₃ = 40.78 r ₅ = ∞ Eccentricity δ = 0.2474, δ · ω /H=14.9 Example 2 f = 1.000, F-number = 1.741, 2ω = 60 °, Image height = 0.5013 Oblique angle θ = 7.5 ° r ₁ = ∞ d ₁ = 0.7602 n ₁ = 1.51633 ν ₁ = 64.15 r ₂ = ∞ (aperture) d ₂ = 1.5674 n ₂ = 1.883 ν ₂ = 40.78 r ₃ = 1.5757 d ₃ = 0.2506 r ₄ = 1.7288 d ₄ = 1.7128 n ₃ = 1.883 ν ₃ = 40.78 r ₅ = ∞ eccentricity δ = 0.2506 , Δ · ω / h = 15.0 Example 3 f = 1.000, F number = 1.966, 2ω = 60 °, Image height = 0.5051 Oblique angle θ = 9.3 ° r ₁ = ∞ d ₁ = 0.7653 n ₁ = 1.883 ν ₁ = 40.78 r ₂ = ∞ (aperture) d ₂ = 1.8261 n ₂ = 1.883 ν ₂ = 40 .78 r ₃ = −1.3324 d ₃ = 0.3088 r ₄ = 2.0768 d ₄ = 1.5862 n ₃ = 1.883 ν ₃ = 40.78 r ₅ = ∞ Eccentricity δ = 0.2525, δ · ω / h = 15.2 Example 4 f = 1.000 , F number = 1.971, 2ω = 115 °, Image height = 0.9259 Oblique angle θ = 6.2 ° r ₁ = ∞ d ₁ = 0.7884 n ₁ = 1.883 ν ₁ = 40.78 r ₂ = ∞ (aperture) d ₂ = 1.3472 n ₂ = 1.883 ν ₂ = 40.78 r ₃ = -1.1241 d ₃ = 0.4630 r ₄ = 2.6352 d ₄ = 1.2014 n ₃ = 1.883 ν ₃ = 40.78 r ₅ = ∞ Eccentricity δ = 0.1389, δ · ω / h = 8.4 5 f = 1.000, F number = 1.994, 2ω = 59 °, Image height = 0.5054 Oblique angle θ = 11.1 ° r ₁ = ∞ d ₁ = 0.6135 n ₁ = 1.883 ν ₁ = 40.78 r ₂ = ∞ d ₂ = 1.2846 n ₂ = 1.883 ν ₂ = 40.78 r ₃ = −1.2699 d ₃ = 0.361 r ₄ = 2.1769 d ₄ = 1.546 n ₃ = 1.883 ν ₃ = 40.78 r ₅ = ∞ Eccentricity δ = 0.2888, δ · ω / h = 17.4 However r _1, r _2, ··· the radius of curvature of each lens surface,
₁ , d ₂ ,... Are the thickness of each lens and the air gap, n
₁ , n ₂ ,... Are the refractive indices of each lens, ν ₁ , ν ₂ ,.
Is the Abbe number of each lens.

FIGS. 1 to 5 are cross-sectional views of the first to fifth embodiments, respectively.

In each of these embodiments, a spherical homogeneous medium lens is used. However, even if an aspherical lens or a gradient index lens is used, each group (lens component) of the present invention is decentered for oblique viewing. Can be configured.

In the above embodiment, the convex lens of the first group and the stop are bonded, and the convex lens of the second group and the imaging surface are bonded. However, they need not be bonded. Further, the present invention does not depend on the shapes of the first and second groups of convex lenses.

FIGS. 10 to 12 show the structure of the distal end of the endoscope to which the objective optical system of the present invention is attached.
Is a front view, FIG. 11 is a sectional view including objective optics, and FIG. 12 is a sectional view of an illumination optical system.

In these figures, reference numeral 1 denotes a main body of the distal end portion of the endoscope, which has three through holes 2, 3 and 4, one end of which is open to the front end surface and the other end is open to the rear end surface. Of these through holes, the through hole 2 is for mounting the objective optical system, and the front end portion is formed as a shallow large-diameter circular hole 5 near the front end. A circular hole 7 having a small diameter is formed. A cylindrical lens holding frame 8 is bonded and fixed to the large-diameter circular hole 5, and a cover glass 9, a diaphragm 10 and a first group positive lens 11 are bonded and held to the holding frame 8. An image guide fiber bundle 14 around which the second group positive lens 12 and the protective tube 13 are wound is fixed to the small diameter portion 7. The through-hole 3 is intended for mounting an illumination optical system, in the vicinity front end, a circular hole 15 of larger diameter, the diameter of the circular hole 16 which is eccentric with respect to the large diameter of the circular hole 15 at its rear Is formed. The direction of the eccentricity of the two circular holes 15 and 16 is the large-diameter circular hole 5 of the through hole 2.
And the direction of the eccentricity of the small-diameter circular hole 7 substantially coincides. An illumination lens 17 is fixed to the large-diameter circular hole 15, and a light guide fiber bundle 18 is attached to the small-diameter circular hole 15.

The through hole 4 is for inserting forceps and the like. The inside of the through hole 4 is formed to have a slightly large diameter near the front end, and a channel base 20 is formed at the tip of the large diameter portion 19. The channel tube 21 is fixed.

The outer periphery of the endoscope main body 1 is formed so that the rear end side is slightly thin, and an outer skin 22 is attached to this end by winding a yarn 23 around the front end. It is fixed at.

As described above, the first group of objective lenses,
The second group is attached to the large-diameter circular hole 5 and the small-diameter circular hole 7 which are eccentric to each other, so that the field of view of the objective lens can be decentered with respect to the optical axis. It is possible to configure an extremely small oblique optical system.
Further, the illumination lens of the illumination optical system can be decentered. In addition, the illumination lens of the illumination optical system and the light guide fiber bundle are also mounted eccentrically, so that the illumination axis of the illumination light also tilts in an oblique direction so that the field of view and the illumination field coincide with each other, so that there is no endoscope without parallax. Is obtained.

[0024]

The endoscope objective optical system according to the present invention is made oblique by merely decentering the lens group (lens component), and does not require the use of a deflector prism or the like. Therefore,
The frame structure for holding the objective optical system is also simplified, and processing and assembly of parts are easy.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a sectional view of a second embodiment of the present invention.

FIG. 3 is a sectional view of a third embodiment of the present invention.

FIG. 4 is a sectional view of a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a fifth embodiment of the present invention.

FIG. 6 is a diagram showing a basic configuration of the present invention.

FIG. 7 is a diagram showing a relationship between an image height and an incident angle of a principal ray on an image plane in the optical system of the present invention.

FIG. 8 is a diagram showing a configuration of a non-eccentric optical system.

FIG. 9 is a diagram showing a relationship between an image height and an incident angle of a principal ray on an image plane in the non-eccentric optical system.

FIG. 10 is a front view of an endoscope assembly holding an objective optical system according to the present invention;

FIG. 11 is a front view including the objective optical system of the assembly.

FIG. 12 is a sectional view of an illumination system of the assembly.

FIG. 13 is a diagram showing a configuration of a conventional oblique endoscope objective optical system.

FIG. 14 is a diagram showing a configuration of another conventional oblique endoscope objective optical system.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 9/00-17/08 G02B 21/02-21/04 G02B 23/24-23/26 G02B 25/00-25 / 04

Claims (4)

(57) [Claims] 1. A brightness stop, a first group having a positive refractive power, and a second group having a positive refractive power, in order from the object side, wherein the brightness stop and the first group are arranged. An endoscope objective optical system which decenters the optical axis of (1) with respect to the optical axis of the second group, and satisfies the following condition. 0 <δ · ω / h <30 where δ is the amount of eccentricity between the optical axis of the first group and the optical axis of the second group, ω is the half angle of view, and h is the image height. 2. A through hole having one end opened to the front end surface and the other end opened to the rear end surface is formed in the front end body, and a first lens holding portion is formed near the front end surface of the through hole. The first
Forming a second lens holding portion eccentrically formed with respect to the lens holding portion, and attaching a brightness stop and a first group having a positive refractive power to the first lens holding portion in order from the front end surface side, A second lens having a positive refractive power in the second lens holding portion;
Endoscope tip assembly with group attached. 3. The endoscope objective optical system according to claim 1, wherein the direction of the eccentricity is a direction having a through hole for inserting forceps or the like. 4. The endoscope tip assembly according to claim 2, wherein the direction of the eccentricity is a direction having a through hole for inserting forceps or the like.