JPH0795154B2 - View-direction changing optical system for endoscopes - Google Patents

Description

The present invention relates to a field-of-view direction changing optical system for an endoscope, which is suitable for a fiberscope, a rigid scope, a videoscope using a solid-state image sensor, and the like.

[Conventional technology]

As a conventional visual field direction changing optical system for an endoscope, for example, one described in Japanese Patent Publication No. 58-56848 is known.

As shown in FIG. 17, this endoscope field-of-view direction changing optical system is provided with a concave lens 2 which is disposed in the endoscope front end frame 1 and receives light from a perspective direction, and a concave lens 2 which is substantially inclined with respect to the perspective direction. A correcting prism 3 which is vertically positioned and has a surface 3a on which the light passing through the concave lens 2 is incident, and a refracting surface 3b on which the incident light passing through the surface 3a is refracted and emitted, and a refracting surface of the correcting prism 3.
A refracting surface 4a that is close to 3b and refracts the light emitted from the correction prism 3, a reflecting surface 4b that reflects the light refracted by the refracting surface 4a, and an exit surface that is positioned substantially perpendicular to the direct viewing direction.
4c, and the light reflected by the reflecting surface 4b is the refracting surface.
The field-of-view direction conversion prism 4 which is reflected by 4a and then exits from the exit surface 4c, and the light exiting from the field-of-view direction conversion prism 4 in the vicinity of the exit surface 4c of the field-of-view direction conversion prism 4 are combined. It is composed of a convex lens 5 for forming an image.

As described above, the viewing direction conversion prism 4 has a refracting action, so that the outside diameter of the viewing direction conversion optical system (in the [Prior Art], the outside diameter is the longitudinal axis direction of the endoscope). When viewed from the front along with.
The same applies to [problems to be solved by the invention]. ) Is possible, and astigmatism caused by having a refracting action is caused by making the incident optical axis from the visual field direction perpendicular to the incident surface of the correcting prism 3 by using the correcting prism 3. To remove it.

Further, as another conventional visual field direction changing optical system, Japanese Patent Laid-Open No.
There is one described in Japanese Unexamined Patent Publication No. 140313. This is
As shown in FIG. 18, the incident surface 6a of the first prism 6 arranged between the concave lens 2 and the convex lens 5 is made perpendicular to the visual field direction, and the first reflecting surface 7a of the second prism 7 is made of a rigid endoscope. In parallel with the longitudinal axis direction, the boundary surfaces 6b, 7b of the first prism 6 and the second prism 7 are formed so as to form an acute angle with the longitudinal axis direction of the rigid endoscope, and these are joined to each other to form the first prism of the second prism 7. Two
It is a reflective surface.

With the above-described structure, the outer diameter of the second prism 7 is increased and the length of the second prism 7 is increased at the same time, so that a prism having a diameter of only about 1 mm can be processed or bonded to a rigid mirror. The assembling work is facilitated, and as a result, the processing accuracy is improved, the play after assembly (deviation between optical members when the optical members are tilted) is reduced, and the deviation in the viewing direction is reduced.

[Problems to be Solved by the Invention]

By the way, in the example shown in FIG. 17, in the actual design, in order to prevent the correction prism 3 from hitting the convex lens 5 and tilting, the longitudinal direction of the correction prism 3 as shown in FIG. It is necessary to design the dimension A of the above to be shorter than the dimension B up to the exit surface 4c of the visual field direction conversion prism 4. However, when A = B, as shown in FIG. 19 (B) or (C), due to the variation in the tolerance of parts,
Since the relative positions of the correction prism 3 and the field-of-view direction conversion prism 4 vary, the optical axes of the convex lens 5 and the concave lens 2 deviate, and the deviation θ in the field of view becomes remarkable. Further, as shown in FIG. 19 (D), the distance between the correction prism 3 and the field-of-view direction conversion prism 4 is wedge-shaped, and as a result, astigmatism occurs and the observed image deteriorates, which is not preferable.
Further, even if the dimension A of the correction prism 3 is shortened as shown in FIG. 19 (A), as shown in FIG. 19 (E) during assembly,
A gap between the endoscope end frame 1 and the outer diameter of the field-of-view direction changing optical system causes a gap between the adjacent spaces, and as a result, an astigmatism is generated and an observed image is deteriorated, which is preferable. Absent. The same applies to the case where the adjacent space is filled with a bonding agent.

Furthermore, in order to reduce the influence of backlash due to the gap between the endoscope front end frame 1 and the outer diameter of the visual field direction changing optical system, it is advantageous that the length of the endoscope in the longitudinal axis direction is as long as possible. However, in the example shown in FIG. 17 and FIG. 19, the length in the longitudinal axis direction is almost the same as the outer diameter of the visual field direction changing optical system. For example, when the inner diameter of the frame 1 is 6.02 mm, the visual field direction changing direction is changed. If the outer diameter of the optical system is 5.97 mm, as shown in FIGS. 20 (A) and 20 (B), the decentering due to the backlash of the prism 4 is σ = 0.025 mm,
ε≈30 ′, and the resulting one-sided blur of the observed image due to the deviation in the perspective direction and the occurrence of astigmatism. Furthermore, the inner diameter of the frame 1 is 3.02 mm and the outer diameter of the visual field direction changing optical system is 2.97 mm.
In the case of, σ = 0.025 mm, but ε≈60 ′, and the influence on the optical performance is further increased.

Further, in the example shown in FIG. 18, the length of the rigid endoscope in the longitudinal axis direction is about four times the outer diameter, and there is little rattling when the prisms 6 and 7 are incorporated in the rigid endoscope, but the prism 6, Since the length of the peripheral edge of each one of the two ends used for positioning of 7 is extremely short, positioning is extremely difficult, and as a result, when joining,
As shown in FIG. 21 (A), a wedge-shaped gap is formed on the joint surface, or as shown in FIG. 21 (B), the prisms 6 and 7 are joined so that their central axes with respect to the outer diameters are displaced from each other. It is easy to cause a deviation in the visual field direction and an astigmatism, which is not preferable.

Further, the prisms 3, 4, and 7 are not preferable because they have three polishing surfaces and their shapes are complicated, so that it takes time to process and the cost is high.

In view of the above problems, the present invention is less likely to deteriorate the optical performance due to the deviation of the visual field direction and the astigmatism due to the decentering caused by the backlash of the prism when incorporated in the endoscope, and the prism The objective is to provide a field-of-view direction changing optical system for endoscopes that is easy to process and assemble and is inexpensive.

[Means and Actions for Solving the Problems]

The endoscope field-of-view direction changing optical system according to the present invention has a refracting surface, a reflecting surface, and an exit surface, and makes incident light from a perspective direction refracted by the refracting surface and then reflected by the reflecting surface. Is disposed on the exit side of the visual field direction conversion prism, and is made to exit from the visual field direction conversion prism after being reflected by the refraction surface and then emitted from the exit surface. An optical member having a refracting surface for refracting and an exit surface for exiting to the image side, for suppressing rattling of the incorporated position of the entire visual field direction conversion optical system,
Arranged along the longitudinal axis direction of the endoscope, the shape and size of the outer diameter when viewed from the front along the longitudinal axis direction of the visual field direction conversion prism and the longitudinal axis direction of the optical member. It is characterized in that the shape and size of the outer diameter when viewed from the front are equal to each other.

Further, it is preferable that the reflecting surface and the exit surface of the visual field direction changing prism are formed of a common plane.

Also, the shape of the outer diameter when viewed from the front along the longitudinal axis direction of the visual field direction conversion prism, the shape equal to the size, the outer diameter when viewed from the front along the longitudinal axis direction of the size. It is preferable that the correction prism is provided in front of the refraction surface of the field-of-view direction conversion prism, and the incident surface of the correction prism is arranged substantially perpendicular to the perspective direction.

Further, it is preferable to dispose a concave lens in front of the entrance surface of the correction prism.

Further, it is preferable to dispose a concave lens in front of the refracting surface of the visual field direction conversion prism.

Furthermore, the length of the visual field direction conversion prism and the optical member on the optical axis along the longitudinal axis direction of the endoscope is 1, and the outer diameter when viewed from the front along these longitudinal axis directions is When d is set, it is preferable that the following conditions are satisfied.

1.2 <l / d <4 Furthermore, the length on the optical axis of the correction prism, the view direction changing prism and the optical member along the longitudinal axis direction of the endoscope is 1, and It is preferable that the following conditions are satisfied, where d is the outer diameter when viewed from the front side.

1.2 <l / d <4 That is, FIG. 1 shows the basic configuration of the optical system of the present invention.
This, as shown in the figure, has a refracting surface 4a having a refracting function positioned substantially perpendicular to the incident optical axis from the perspective direction, and a reflecting surface 4b for reflecting the light refracted by the refracting surface 4a, A field-of-view direction conversion prism 4 configured such that the light reflected by the reflecting surface 4b is reflected by the refracting surface 4a, and an outer diameter (as shown above [means and action for solving the problem]
Also in the above, the outer diameter refers to that seen from the front along the longitudinal axis direction of the endoscope. [Example] The same applies to the following description. ) Is a circular shape having the same size as the outer diameter of the visual field direction conversion prism 4 and has a refracting action on the light reflected from the refracting surface 4a, and further refracts the light refracted by the refracting surface 8a. And a stabilizing lens 8 for suppressing the shading of the incorporated position of the entire visual field direction conversion optical system having an exit surface 8b for giving light to an objective lens (not shown) behind, and a surface 4b of the visual field direction conversion prism 4. The surface 8a of the stabilizing lens 8 forms an acute angle with the longitudinal axis directions L and L'of the endoscope, and is adjacent or joined.

Therefore, as shown in FIG. 1, the field-of-view direction conversion prism 4 and the stabilizing lens 8 are both formed by cutting a round bar into round slices. Therefore, the positioning at the time of approaching or joining the two is an elongated tube (the tip of the endoscope). It can be done accurately simply by dropping it into the frame 1) in order, and there is no wedge-shaped gap in the joint surface as in the above-mentioned conventional example, and the center axes with respect to the outer diameters of both are not joined together. Also, there are few deviations in the viewing direction and astigmatism.

Further, since the polishing surfaces of the field-of-view direction conversion prism 4 and the stabilizing lens 8 are the front and rear surfaces, and the production is easy, the cost is low.

In the configuration shown in FIG. 1, it is desirable that the perspective direction be less than 60 ° with respect to the longitudinal axis direction of the endoscope, and if it becomes 60 ° or more, the viewing direction conversion prism 4 as shown in FIG. The shape and size of the outer diameter are different from the shape and size of the outer diameter of the stabilizing lens 8, and the backlash when assembled in the endoscope becomes large, which is not preferable.

Further, in FIG. 1, an intersection point M of an incident optical axis from the visual field direction and a refracting surface 4a substantially perpendicular thereto and a point L for reflecting a light ray reflected from the reflecting surface 4b on the surface 4a are close to each other. At this point, the incident light flux and the reflected light flux may overlap.
Also, since the angle of the incident light on the surface 4a as a reflecting surface is sharp,
The surface 4a is provided with an expensive reflective coating made of aluminum or the like. Therefore, as shown in FIG. 3, if the correction prism 3 is provided on the object side of the visual field direction conversion prism 4, that is, in front of the refracting surface 4a, the position M of the incident optical axis on the refracting surface 4a is increased.
Is lowered and the distance from the intersection L ″ of the surface 4a with the reflection optical axis is increased, so that it is possible to prevent the mutual light beams from overlapping each other.
Further, the angle of the incident light ray on the surface 4a as the reflecting surface becomes gentler than in the case of FIG. 1 and the condition of total reflection is satisfied, so that an expensive reflective coating using aluminum or the like is not necessary. However, at this time, a slight air layer, a bonding agent layer having a low refractive index, or a coating layer is required between the adjoining surfaces 4a and 3b of the field-of-view direction conversion prism 4 and the correction prism 3 for total reflection.

Further, in FIG. 3, since the correction prism 3 is used, the refracting surface 3a substantially perpendicular to the incident optical axis from the visual field direction is used.
The intersection point M at is closer to the point L through which the central axis of the prism diameter passes, as compared with the case of FIG. Therefore, for example, when the concave lens 2 is required to increase the viewing angle, the lower space is narrow in FIG. 1 and a too large lens cannot be arranged, but in FIG. 3, a sufficient lower space is obtained and a large lens is arranged. it can.

Further, as shown in FIG. 4, if the refracting surface 4a of the field-of-view direction converting prism 4 and the reflecting surface 4b adjacent to the stabilizing lens 8 are made parallel to each other, one surface is polished in processing the field-of-view direction converting prism 4. It is easier to polish the other surface in parallel with it than in the case of the wedge-shaped field-of-view direction changing prism 4 shown in FIG. 1, and it is possible to polish a plurality of one-side polished ones at a time. The processing time is shortened and the cost is low, which is preferable.

The viewing direction changing optical system shown in FIGS. 1, 3, and 4 has a diameter of a cross section perpendicular to the longitudinal axis of the endoscope as d and a length of a central axis LL ′ in the longitudinal direction as l / d is about 2, and it is desirable to satisfy the following conditions when used in various endoscopes.

When 1.2 <l / d <4 l / d <1.2, as described in the prior art in which the length in the longitudinal axis direction is almost the same as the outer diameter of the visual field direction changing optical system, as shown in FIG. The rattling of ε shown in (3) becomes large, and deviation in the visual field direction and astigmatism occur, which is not preferable. When l / d> 4, the optical path length in the prism becomes long, the light flux spreads, and the height of the light beam at the exit surface 8b to the objective lens behind the stabilizing prism 8 becomes large, resulting in an outer diameter. In the case of an endoscope that cannot take a large angle, the light flux is eclipsed and the periphery of the observed image becomes dark, which is not preferable.

In addition, the actual ε in the case of FIG. 1 is d≈l in the conventional example as shown in FIG. 19 in view of the outer diameter and the length in the longitudinal axis direction of the visual field direction changing optical system. Since 2d≈l, for example, if the inner diameter of the endoscope front end frame is 6.02 mm and the outer diameter of the visual field direction changing optical system is 5.97 mm, then ε≈15 ′, which is half that of the conventional example. This is effective in preventing deviation in the visual field direction and occurrence of astigmatism.

Further, it is desirable that the refractive index n of the material used for the visual field direction changing optical system of the present invention is relatively large such that n> 1.6. Even if the length l is long, the air-equivalent optical path length is short when the refractive index is large. For example, when l = 4, n = 1.5, the air-equivalent optical path length is about 2.7, but l = 4, n = 1.9. In this case, the air-equivalent optical path length is about 2.1, and although l is long, the spread of light rays is small, which is effective for endoscopes with a limited outer diameter.

Further, increasing the refractive index of the material used for the view direction changing optical system facilitates total reflection on the surfaces 4a and 4b shown in FIGS. 1 and 3, and as a result, reflection using expensive aluminum or the like. This is effective because it eliminates the need for coating.

〔Example〕

The present invention will be described below in detail based on the illustrated embodiments by assigning the same reference numerals to the same members as those in the above-mentioned conventional example.

FIGS. 5 to 7 show first to third embodiments, respectively, which are a refracting surface 4a positioned perpendicularly to the incident optical axis from the perspective direction, and a light refracted by the refracting surface 4a. The viewing direction conversion prism 4 having a reflection surface 4b that reflects light, and light reflected by the reflection surface 4b is reflected by the refraction surface 4a.
Is equipped with. The refracting surface 4a is provided with a reflective coating such as aluminum according to the width of the light beam on the fulcrum L with respect to the optical axis so as not to block the light beam on M. On the image side of the prism 4, the outer diameter is a circle having the same size as the outer diameter of the visual field direction conversion prism 4, and the refracting surface 8a refracting the reflected light from the refracting surface 4a and the refracting surface 8a. A stabilizing lens 8 having a refracting surface 8b for emitting refracted light to a rear objective lens is arranged so as to be bonded to the surface 4b, and the outer diameter d of the bonded prism 4 and lens 8 is set to 1. When the intersections of the longitudinal center axis and the surfaces 4a and 8b are L and L ', respectively, and the distance between them is l, l = 2,1.6,1.7 for the first to third embodiments, respectively. , The longitudinal axes of the prism 4 and the lens 8 are set longer than the outer diameter d.

These embodiments are configured as described above, and both the field-of-view direction conversion prism 4 and the stabilizing lens 8 are basically formed by cutting a round bar into a ring shape, so that the positioning at the time of joining the two can be accurately performed. Therefore, unlike the conventional example, a wedge-shaped gap is not formed on the joint surface, and the center axes of the outer diameters of the both are not displaced from each other. Further, since the longitudinal axis lengths of the prism 4 and the lens 8 are set longer than the outer diameter d, there is little backlash due to the inclination when assembled in the frame. Therefore, the deviation of the visual field direction and the generation of astigmatism are prevented, and the deterioration of the optical performance is small.

Further, the visual field direction changing prism 4 of the first embodiment has a shape in which a round bar is simply sliced and also has two processed surfaces, so that it is easy to manufacture and is low in cost. Further, in the second and third embodiments, the processed surfaces are three, but since the surfaces 4a and 4b are parallel to each other, when polishing one surface from the other and polishing the other surface in parallel, a plurality of surfaces can be processed at once. Can be processed, and as a result, it takes less time to process and can be made in large quantities, so the cost is low and effective.

Also, by changing the inclination of the processed surface of the prism 4 and the lens 8, the oblique direction is set to, for example, 15 ° (first embodiment), 45 ° (second embodiment), 55 ° (third embodiment). Can be different.

FIGS. 8 to 11 show the fourth to seventh embodiments, respectively, which show the shape and size of the outer diameter of the view direction changing prism 4 in front of the object side of the view direction changing prism 4, that is, the refracting surface 4a. The third embodiment is different from the first to third embodiments in that the correction prism 3 having the same shape and the same outer diameter as the above is provided, and that the exit surface 8b of the stabilizing lens 8 is a flat surface. By providing the correcting prism 3, the position M of the incident optical axis on the incident surface 3a of the correcting prism can be increased, and it should be coincident with the intersection L with the longitudinal axis direction as in the sixth and seventh embodiments. Is also possible. Therefore, as shown in FIG. 3, when the concave lens 2 is placed on the object side of the correction prism 3, that is, in front of the entrance surface 3a in order to increase the viewing angle, the position of the incident optical axis on the entrance surface 3a is high. , Not limited to the space below the prism,
It becomes possible to provide a large concave lens 5.

Further, since the exit surface 8b of the stabilizing lens 8 is a flat surface, this visual field direction changing optical system does not have a function of condensing and diverging power, that is, light. Even when the optical system is detachably attached as an attachment, it is effective because the viewing direction can be freely selected without largely affecting the viewing angle and various aberrations.

In addition, the fifth to seventh embodiments have the advantage that the surfaces 4a and 4b of the visual field direction conversion prism 4 are parallel to each other, so that they can be made cheaper and the cost is lower as in the second and third embodiments.

12 and 13 show the eighth and ninth embodiments, respectively, which are a view direction changing prism 4 and a stabilizing lens 8.
A brightness diaphragm S is provided between the correction prism 3 and the field-of-view direction conversion prism 4, and an image guide IG formed by bundling fiber fibers as a means for transmitting an image formed by the objective lens OB. And a solid-state image sensor CCD. CG is a cover glass.

The brightness of an image when using the image guide IG or the solid-state imaging device CCD is determined by a brightness diaphragm that limits a light beam at an appropriate position in an objective optical system. In this embodiment, a brightness diaphragm is arranged in the vicinity of the visual field direction conversion prism 4 so that the brightness can be easily determined.

Incidentally, in the case of a so-called relay lens having a so-called relay lens which transmits an image while forming the image as a means for transmitting an image formed by an objective lens like a rigid endoscope, the brightness of the image is limited by this image transmission optical system. It is not necessary to provide an aperture stop in the objective optical system.

FIG. 14 shows the objective optical system OB of the rigid endoscope using the tenth embodiment.
FIG. 15 shows the configuration of S, and FIG. 15 shows the entire optical system of a rigid endoscope in which the objective optical system OBS, the image transmission optical system RL, and the eyepiece optical system OC are combined. That is, the objective optical system OB
The image I formed by S is transferred to I ′, I ″, I by the image transmission optical system RL.
, I ′, I ″ are transmitted one after another and magnified by the eyepiece optical system OC for observation. Inside the narrow cavity of the elongated hole or the entrance that cannot be observed from the outside, for example, inside the body or the engine of an airplane. It is effective because it can be observed in good images without laparotomy or disassembling.

The aberration curve diagrams of the optical system shown in FIGS. 14 and 15 are as shown in FIG. 16, and it can be seen that various aberrations are well corrected.
However, this is an evaluation in the final image I ″. The eyepiece optical system OC is excluded. Further, the design data is as follows, which is when the outer diameter of the visual field direction conversion prism 4 is 1. It is a thing.

γ ₁ = ∞ d ₁ = 0.1091 n ₁ = 1.51633 γ ₂ = ∞ d ₂ = 0.0727 γ ₃ = ∞ d ₃ = 0.0727 n ₂ = 1.80610 γ ₄ = 0.2735 d ₄ = 0.0727 γ ₅ = ∞ d ₅ = 0.4839 n ₃ = 1.78800 γ ₆ = ∞s (virtual aperture) d ₆ = 2.0980 n ₄ = 1.78800 γ ₇ = -1.1363 d ₇ = 0.4590 γ ₈ = 1.1371 d ₈ = 0.4655 n ₅ = 1.60311 γ ₉ = -1.1371 d ₉ = 0.4473 n ₆ = 1.78472 γ ₁₀ = 12.0567 d ₁₀ ＝ 0.5055 γ ₁₁ ＝ －0.8385 d ₁₁ ＝ 0.7636 n ₇ ＝ 1.78472 γ ₁₂ ＝ ∞ d ₁₂ ＝ 0.4000 n ₈ ＝ 1.78800 γ ₁₃ ＝ －1.4127 d ₁₃ ＝ 1.6720 γ ₁₄ ＝ 4.1364 d ₁₄ = 8.7273 n ₉ = 1.62004 γ ₁₅ ＝ ∞ d ₁₅ ＝ 0.6145 γ ₁₆ ＝ 5.6204 d ₁₆ ＝ 0.9636 n ₁₀ ＝ 1.65160 γ ₁₇ ＝ −1.2698 d ₁₇ ＝ 0.4909 n ₁₁ ＝ 1.80610 γ ₁₈ ＝ －2.8364 d ₁₈ ＝ 1.0218 γ ₁₉ ＝ ∞ d ₁₉ ＝ 8.7273 n ₁₂ ＝ 1.62004 γ ₂₀ ＝ －4.1364 d ₂₀ ＝ 1.4545 γ ₂₁ ＝ 4.1364 d ₂₁ ＝ 8.7273 n ₁₃ ＝ 1.62004 γ ₂₂ ＝ ∞ d ₂₂ ＝ 0.6145 γ ₂₃ ＝ 5.6204 d ₂₃ ＝ 0.9636 n ₁₄ = 1.65160 γ ₂₄ = 1.2698 d ₂₄ ＝ 0.4909 n ₁₅ = 1.80610 γ ₂₅ ＝ −2.8364 d ₂₅ ＝ 1.0218 γ ₂₆ ＝ ∞ d ₂₆ ＝ 8.7273 n ₁₆ ＝ 1.62004 γ ₂₇ ＝ －4.1364 d ₂₇ ＝ 1.4545 γ ₂₈ ＝ 4.1364 d ₂₈ ＝ 8.7273 n ₁₇ ＝ 1.62004 γ ₂₉ ＝ ∞ d ₂₉ ＝ 0.6145 γ ₃₀ ＝ 5.6204 d ₃₀ ＝ 0.9636 n ₁₈ ＝ 1.65160 γ ₃₁ ＝ −1.2698 d ₃₁ ＝ 0.4909 n ₁₉ ＝ 1.80610 γ ₃₂ ＝ －2.8364 d ₃₂ ＝ 1.0218 γ ₃₃ ＝ ∞ d ₃₃ ＝ 8.7273 n ₂₀ ＝ 1.62004 γ ₃₄ ＝ －4.1364 d ₃₄ = 1.4545 γ ₃₅ = 4.1364 d ₃₅ ＝ 8.7273 n ₂₁ ＝ 1.62004 γ ₃₆ ＝ ∞ d ₃₆ ＝ 0.6145 γ ₃₇ ＝ 5.6204 d ₃₇ ＝ 0.9636 n ₂₂ ＝ 1.65160 γ ₃₈ ＝ −1.2698 d ₃₈ ＝ 0.4909 n ₂₃ ＝ 1.80610 γ ₃₉ ＝ −2.8364 d ₃₉ ＝ 1.0218 γ ₄₀ ＝ ∞ d ₄₀ ＝ 8.7273 n ₂₄ ＝ 1.62004 γ ₄₁ ＝ －4.1364 d ₄₁ ＝ 1.4545 γ ₄₂ ＝ 4.1364 d ₄₂ ＝ 8.7273 n ₂₅ ＝ 1.62004 γ ₄₃ ＝ ∞ d ₄₃ ＝ 0.6145 γ _{44 = 5.6204 d 44 = 0.9636 n 26} = 1.65160 γ 45 = -1.2698 d 45 = 0.4909 n 27 = 1.80610 γ 46 = -2.8364 d 46 = 1.0218 γ 47 = ∞ d 47 = 7.8836 n 28 = 1.62004 γ 48 = ∞ d 48 = 0.7891 n ₂₉ = 1.51633 γ ₄₉ = -9.1756 d ₄₉ = 4.41 85 γ ₅₀ ＝ 4.4036 d ₅₀ ＝ 0.3636 n ₃₀ ＝ 1.78472 γ ₅₁ ＝ 1.6418 d ₅₁ ＝ 1.0909 n ₃₁ ＝ 1.67003 γ ₅₂ ＝ －4.6175 d ₅₂ ＝ 1.3455 γ ₅₃ ＝ ∞ d ₅₃ ＝ 0.3636 n ₃₂ ＝ 1.51633 γ ₅₄ ＝ ∞ Object distance 5.4545 Image height (φ / 2) 0.3564 Angle of view (2ω) 65 ° Focal length (1st to 49th surface) -0.654 Focal length (50th to 54th surface) 4.163 FNo. (1st to 49th surface) 6.993 , Γ ₁ , γ ₂ , ... Are radii of curvature of the respective lens surfaces, d ₁ , d ₂ , ... Are the intervals between the lens surfaces, and n ₁ , n ₂ ,.

In each embodiment, the lens may have an inhomogeneous medium or an aspherical surface.

〔The invention's effect〕

As described above, the endoscope visual field direction changing optical system according to the present invention has an optical performance that is caused by the deviation of the visual field direction and the generation of astigmatism due to the decentering caused by the backlash of the prism when incorporated in the endoscope. There is little deterioration, and prism processing,
It has important practical advantages that it is easy to assemble and the cost is low.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of the optical system of the present invention, FIG. 2 is a diagram showing a case where a perspective direction angle is large in FIG. 1, and FIGS. 3 and 4 are other configurations of the optical system of the present invention, respectively. FIGS. 5 to 7 are views showing first to third embodiments of the visual field direction changing optical system for an endoscope according to the present invention, and FIGS. 8 to 8 respectively.
FIG. 11 is a diagram showing the fourth to seventh embodiments, FIG. 12 and FIG.
13 shows the eighth and ninth embodiments, and FIG. 14 shows the tenth embodiment.
FIG. 15 is a diagram showing the configuration of an objective optical system using an embodiment, FIG.
The figure which shows the constitution of the optical system which combines the objective optical system of Figure 14 and the image transmission optical system and the eyepiece optical system, Figure 16 the aberration curve figure of the optical system which is shown in Figure 14, 15, Figure 17 and FIG. 18 is a diagram showing the structure of the conventional example, FIGS. 19 and 20 are diagrams showing the problems of the conventional example of FIG. 17, and FIG. 21 are the problems of the conventional example of FIG. It is a figure. 1 ... End frame of endoscope, 2 ... Concave lens, 3 ... Auxiliary prism, 4 ... View direction changing prism, 3a, 4a, 8a ... Refractive surface, 3b ... Surface, 4b ... Reflective surface, 8 ... Stabilizing prism, 8b ... Emitting surface, S ... Brightness diaphragm.

Claims (7)

[Claims] 1. A refracting surface, a reflecting surface, and an exiting surface, wherein incident light from a perspective direction is refracted by the refracting surface, then reflected by the reflecting surface, and subsequently reflected by the refracting surface. A visual field direction changing prism adapted to emit light from the exit surface, and a refracting surface arranged on the exit side of the visual field direction converting prism for refracting and refracting light emitted from the visual field direction converting prism and exiting to the image side. And an optical member for suppressing rattling of the built-in position of the entire field-of-view direction conversion optical system, which is arranged along the longitudinal axis direction of the endoscope. It is characterized in that the shape and size of the outer diameter when viewed from the front along the axial direction and the shape and size of the outer diameter when viewed from the front along the longitudinal axis direction of the optical member are equal to each other. View for endoscope Conversion optical system. 2. The visual field direction changing optical system for an endoscope according to claim 1, wherein the reflecting surface and the exit surface of the visual field direction converting prism are formed of a common plane. 3. The shape of the outer diameter of the viewing direction conversion prism when viewed from the front along the longitudinal axis direction, the shape equal to the size, and the size of the outer diameter when viewed from the front along the longitudinal axis direction. The correction prism having an outer diameter is provided in front of the refraction surface of the field-of-view direction conversion prism, and the incident surface of the correction prism is arranged substantially perpendicular to the perspective direction. FOV direction changing optical system for endoscopes. 4. The visual field direction changing optical system for an endoscope according to claim 3, wherein a concave lens is arranged in front of the entrance surface of the correction prism. 5. The view direction changing optical system for an endoscope according to claim 1, wherein a concave lens is arranged in front of the refracting surface of the view direction changing prism. 6. The length of the viewing direction conversion prism and the optical member on the optical axis along the longitudinal axis direction of the endoscope is l, and the length when viewed from the front along these longitudinal axis directions is outside. The visual field direction changing optical system for an endoscope according to claim 1, wherein the following condition is satisfied when the diameter is d. 1.2 <l / d <4 7. The length on the optical axis of the correction prism, the field-of-view direction conversion prism, and the optical member along the longitudinal axis direction of the endoscope is 1, and viewed from the front along these longitudinal axis directions. The visual field direction changing optical system for an endoscope according to claim 3, wherein the following condition is satisfied, where d is the outer diameter in such a case. 1.2 <l / d <4