JP3290824B2 - Stereoscopic rigid endoscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rigid stereoscopic endoscope capable of stereoscopically observing a subject.

[0002]

2. Description of the Related Art In recent years, with the development of surgical techniques, endoscopes for observing the inside of the abdominal cavity by making a small hole in the abdomen using a rigid endoscope instead of conventional open surgery, and performing surgery Lower surgery is becoming more widespread.

[0003] Until now, observations have been made with a device combining a rigid endoscope and a TV camera, but since there is no depth information, the operation has taken a long time. However, recently, a stereoscopic rigid endoscope system having depth information has been developed. FIG. 9 is a conceptual diagram of the system 61, which basically includes the following four systems.

[0004] A stereoscopic rigid endoscope 63 having an insertion section 62 to be inserted into a subject, including an observation optical system, an image pickup device, and an illumination optical system, and acquiring two object images having parallax.
A video signal processing system 64 for processing a signal obtained by the imaging device; a stereoscopic display system 65 for providing a viewer with a stereoscopic image from a video signal generated by the video signal processing system 64; An illumination light source device 66 for supplying illumination light to the endoscope 63.

A conventional stereoscopic rigid endoscope 41 having a configuration shown in FIG. 10 (a) has two completely independent optical systems arranged in parallel and forms an image on imaging elements 16A 'and 16B'. I do.
That is, the two objective optical systems 2A 'and 2B' take in left and right images having parallax with each other and convert the respective images into the relay optical system 3A.
The optical path is transmitted by A 'and 3B', the optical path is changed by the axial interval expanding optical systems 4A 'and 4B' for expanding the interval between the left and right optical axes, and further the image sensor 16 is passed through the imaging optical systems 15A 'and 15B'
The image is formed on A 'and 16B'.

[0006]

Since the left and right optical systems are independent of each other in the optical system shown in FIG. 10 (a), the optical performance of the left and right optical systems depends on the optical performance such as variation in the viewing direction, magnification, and focus. Since there is a relative difference, optical adjustment for eliminating it is very complicated. Further, since the left and right optical systems are independent of each other, the number of components is increased and the cost is high.

On the other hand, a stereoscopic rigid endoscope 91 of a conventional example (German model G9217980) shown in FIG. 10 (b) has an objective optical system 2 'for forming an object image on an insertion portion and this objective optical system. A relay optical system 3 'for relaying the image 2' and an infinity imaging optical system 9 for forming the final image 4 'of the relay optical system 3' at infinity are incorporated. It has an axis.

[0008] Behind it, a brightness stop 6 'having two apertures and a light beam restricted by the brightness stop 6' are projected onto the image pickup surfaces of image pickup devices 16A 'and 16B' to form images 7A 'and 7B.
Two separate imaging optical systems 5A 'and 5B' (collectively referred to as 5 ') which are arranged in parallel to form an image of B', and an axial interval expanding optical systems 10A and 10B for expanding the interval between the left and right optical axes;
In this configuration, two image sensors 16A 'and 16B' are arranged.

The rigid endoscope 51 for stereoscopic vision has an optical axis commonly used by the objective optical system 2 ', the relay optical system 3', and the infinity imaging optical system 9. Therefore, the drawback that the left and right images have large variations in focus and magnification and the number of parts increases in the configuration of the two optical systems in FIG.

[0010] However, in this configuration, since the axial interval expanding optical systems 10A 'and 10B' for expanding the interval between the left and right optical axes are present, optical adjustment of the prism or the mirror is required, and the adjustment is complicated. In addition, the axis interval expanding optical system 10
Even in the case where A ′ and 10B ′ are not used,
In the configuration of this conventional example, since the center of the imaging surface of the imaging elements 16A 'and 16B' is set on the optical axis of the separation imaging optical systems 5A 'and 5B', the light near the hand (parts other than the insertion portion) is light. There is a problem that it becomes longer in the axial direction and becomes larger, making it difficult to operate.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems, and has as its object to provide a stereoscopic rigid endoscope that can be downsized by shortening the length in the optical axis direction on the hand side. It is another object of the present invention to provide a stereoscopic rigid endoscope which does not require an optical axis-expansion optical system for expanding the optical axis interval on the image pickup device side and allows easy left and right optical adjustment.

[0012]

An insertion part to be inserted into a subject, and an objective optical system arranged at the tip of the insertion part and having one optical axis for forming an image of an object. Having a common optical axis with the objective optical system, and having a relay optical system for transmitting an image formed by the objective optical system in the proximal direction, and having two optical axes, and A separation imaging optical system that guides a light beam from the final image formed on the hand side of the relay optical system obliquely rearward and separates and forms two images having parallax with each other; An image pickup device for picking up left and right images, and a light beam from the final image of the relay optical system is guided obliquely rearward by a separate image pickup optical system to form the left and right images on the image pickup device. The length in the direction can be shortened to enable miniaturization.

Further, with this configuration, the axial interval expanding optical system can be made unnecessary, and in this case, the adjustment of the axial interval expanding optical system is not required, and the optical system on the hand side can be downsized.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. 1 to 5 relate to a first embodiment of the present invention, FIG. 1 shows a schematic configuration of a stereoscopic rigid endoscope of the first embodiment of the present invention, and FIG. 2 shows a stereoscopic view of the first embodiment. 3A shows a specific configuration of the optical system of the rigid endoscope, FIG. 3A is a functional schematic diagram of the optical system of FIG. 2, and FIG. 3B is a conventional optical system for comparison. Is shown in a functional schematic diagram, FIG. 4 shows a part of a separation imaging optical system, and FIG. 5 shows an aspherical coordinate system.

As shown in FIG. 1, a stereoscopic rigid endoscope 11 according to a first embodiment of the present invention is a direct-view rigid endoscope unit (abbreviated as a scope unit) 12a, and is detachably attached to the scope unit 12a. And a camera head unit 13 to be connected. Further, instead of the direct-view type scope 12a, a perspective type scope 12b and a camera head 13 detachably connected to the scope 12b may be used.

The scope section 12a or 12b includes an insertion section 14 which is rigid and elongated so as to be inserted into a subject.
A large-diameter grip 15 is formed at the rear end of the insertion portion 14, and the rear end of the grip 15 has a camera head 13.
Can be detachably connected.

A light guide (not shown) is inserted into the insertion portion 14. The light guide reaches a light guide base on a side portion of the grip portion 15, and is connected to a light source device via a light guide cable (not shown) to thereby form a light source. The illumination light from the device is transmitted and emitted forward or obliquely forward from an illumination window at the distal end of the insertion section 14 to illuminate an object 1 (see FIG. 2) such as an affected part in the subject. The illuminated object 1 forms an image of the object 1 at the image forming position by the objective optical system 2 disposed at the distal end of the insertion section 14.

On the optical axis O of the objective optical system 2 (in the case of a perspective type, the optical axis of the rear lens group of the objective optical system 2), the relay optical system 3 is disposed in the insertion portion 14 and the grip portion 15. , The images are sequentially connected to the rear side, and the images are transmitted to the rear side. Then, the final image 4 transmitted to the position behind the relay optical system 3 (see FIG. 2)
Tie. The final image 4 is stored in the camera head unit 13 by the separated imaging optical systems 5A and 5B (the stop 6 shown in FIG. 2).
The images 7A and 7B are formed at the left and right image forming positions on the obliquely rear side, respectively, by the separate imaging optical system 5). The imaging planes of the imaging elements 16a and 16b are arranged at the left and right image forming positions, and photoelectrically convert the formed left and right images 7A and 7B, respectively. Since the left and right imaging positions are also the positions of the imaging planes, the images 7A and 7B are also referred to as imaging plane images 7A and 7B.

FIG. 2 shows a specific configuration of the entire optical system when the camera head unit 13 is mounted on, for example, a direct-view type scope unit 12a, and FIG. 3A is a functional schematic diagram of the optical system. ing.

In the optical system of this embodiment, the separated imaging optical system 5 and the following are decentered optical systems having two optical axes, and at least five optically determined optical axes (optical axis O of the objective / relay optical system, right and left Optical axes Oa, O of two separate imaging optical systems 5A, 5B
b, imaging plane central axes 17a and 17b) of the two left and right imaging elements 16A and 16B.

As shown in FIG. 2, two light beams emitted from the center of the object 1 reach the position of the final image 4 via the objective optical system 2 and the relay optical system 3 arranged on the optical axis O. The light beam emitted from the position of the final image 4 passes through an oblique optical path passing through each opening of the stop 6 formed eccentrically right and left behind the optical axis O, and is eccentric right and left from the optical axis O. Separate imaging optical systems 5A and 5B arranged in Oa and Ob, optical filter group 1
7 so as to reach the center of the imaging surface of the left and right image pickup devices 16A and 16B which are further decentered to the left and right than the optical axes Oa and Ob. ) Is set.

In FIG. 2, two light beams emitted from the center of the object 1 reach the position of the final image 4 via the objective optical system 2 and the relay optical system 3 on the common optical axis O as described above. Final image 4
The light beams emerging from the position are further separated and imaged by optical systems 5A and 5A.
B, the light reaches the centers of the imaging surfaces of the left and right imaging elements 16A and 16B via the optical filter group 17, respectively.
The light rays of the book can be regarded as left and right stereoscopic axes determined optically.

The inward angle shown in the data to be described later is a scissor angle between the two stereoscopic axes on the object 1 side, and this size affects the stereoscopic effect. The larger the inward angle, the greater the three-dimensional effect, and the easier it is to capture information in the depth direction. However, if the inward angle is too large, the viewer tends to be tired, so it is necessary to set an appropriate inward angle according to the application. .

In the optical system of this embodiment, the inward angle tends to be smaller than that of the conventional type shown in FIG.
The objective optical system 2 and the relay optical system 3 are made thicker than the rigid endoscope for non-stereoscopic vision and have a large numerical aperture so that an appropriate inward angle can be obtained.

The objective optical system 2 is designed on the assumption that the objective optical system 2 is made oblique. Although FIG. 2 is a direct view, a perspective type can also be configured by replacing the long rod-shaped member 2a on the object side with a perspective prism. Another feature of the objective optical system 2 is that distortion is corrected using an aspheric surface.

The concave surface of the plano-concave lens 2b at the tip is an aspherical surface, and the curvature of the aspherical surface is reduced toward the periphery of the lens, thereby suppressing excessive refraction of the principal ray and correcting distortion. ing. If distortion remains, the resulting image distortion is illusioned with information in the depth direction, and it is difficult to obtain an accurate three-dimensional effect, which is not desirable. 65 ° angle of view when distortion is not corrected
Is about -15%, but in the data of the present embodiment, it is -2.88%, and the distortion is sufficiently corrected.

The relay optical system 3 has a partial optical system composed of three relay lens systems 3a, 3b and 3c for performing image transmission, for example, three times, and the relay lens systems 3a and 3b have the same configuration. The relay lens systems 3a and 3b are constituted by lens systems which are symmetrical back and forth along the optical axis direction, and are designed so that the image magnification is -1 and the entrance pupil and exit pupil are at infinity. The relay lens system 3c is designed to have an image magnification of -1.16 times, an entrance pupil position at infinity, and a finite exit pupil position.
Also, the configuration of the relay lens system 3c is
The reason why they are changed to a and 3b is to match the exit pupil position of the relay optical system 3 with the entrance pupil position of the separation imaging optical system 5 (the position of the brightness stop 6 in FIG. 2).

If the position of the exit pupil of the relay optical system 3 deviates from the position of the entrance pupil of the separation imaging optical system 5, off-axis light flux cannot pass through the left and right apertures of the aperture stop 6, and the image around the visual field is blurred. Occurs. Therefore, the relay lens system 3
In (c), a field lens 3d having a positive power is disposed closest to the relay final image 4, and the exit pupil position is controlled by the power.

In the case where the scope section 12a and the camera head section 13 are separated from each other due to the configuration of the product, a focus adjustment mechanism for adjusting the focus at the time of assembling the scope section is provided in the relay optical system 3. Good. Specifically, a mechanism for moving at least a part of the lens in the relay lens system 3c in the optical axis direction may be provided. In this embodiment, 3 in FIG.
Focus adjustment can be performed by moving d alone in the optical axis direction.

The light beam incident on the field lens 3d is designed to be a parallel light beam. As a focus adjustment method that does not move the lens, the camera head 1
3 for determining the mechanical position when connecting to the scope 3
There is a method of making the distance between the contact position a or 12b and the relay final image 4 mechanically variable.

In this embodiment, the aperture stop 6 is disposed at the forefront of the separated image pickup optical system 5. In this case, it is desirable to separate the scope 12a or 12b and the camera head 13 in the product configuration either before or after the aperture stop 6.

The aperture stop 6 is moved to the scope section 12a or 12
b, it is mechanically separate from the separated imaging optical system 5 in the camera head unit 13, so that the left and right optical axes of the separated imaging optical system 5 and the left and right apertures of the aperture stop 6 are aligned. Careful machine design is required. In particular, scope unit 1
When the camera head 13 is relatively rotated with the camera head 2a or 12b, the aperture stop 6 in the scope 12a or 12b is not synchronized with the rotation of the scope 12a or 12b, but is synchronized with the camera head 13 so that the light is Axis misalignment must be avoided.

The left and right separated imaging optical systems 5A and 5B of the separated imaging optical system 5 are first and second separated imaging lens systems 5 respectively.
The first separated imaging lens system 5c, which is composed of two partial optical systems c and 5d and serves as a front lens group, includes imaging elements 16A and 16D.
The positive cemented meniscus lens having a convex surface on the B side, and the second separated imaging lens system 5d serving as a rear lens group include a positive single lens and a negative single lens in order from the first separated imaging lens system 5c side. The reason why the second separation imaging lens system 5d is configured with the positive and negative power arrangement is that the principal point position is set to the first separation imaging lens system 5d.
This is because the back focus is shortened on the c side, and the length of the optical system on the hand side is shortened even a little.

First and second separated imaging lens systems 5c, 5d
Are designed to obtain a parallel light flux between the scope section 12a or 12b and the camera head section 13a.
Is effective when the components are separated from each other, and is very effective when the focus of the camera head unit 13 is adjusted. In the focus adjustment by moving the lens in the optical axis direction, the image magnification usually changes at the same time. For this reason, when focus adjustment must be performed independently for the left and right sides, a difference in right and left magnification occurs.

In the configuration of the present embodiment, since the space between the first and second separated imaging lens systems 5c and 5d is a parallel light beam,
Even if one of them is moved for focus adjustment, the image magnification hardly fluctuates. Therefore, even if focus adjustment is performed independently for the left and right, there is no difference in magnification between the left and right, and there is no adverse effect on stereoscopic vision.

If the moving mechanism of the image pickup devices 16A and 16B in the optical axis direction can be installed, the focus adjustment in the separate image pickup optical system 5 is unnecessary.

The distance d between the optical axes of the left and right separated imaging optical systems 5A and 5B is the distance D between the center axes of both imaging surfaces (simply the center axis distance D).
), It may be difficult to arrange the lenses. In the case of the present embodiment, the left and right separated imaging optical systems 5
Separation imaging optical system 5 on the left and right sides of the optical axis distance d between A and 5B
Since the lens effective diameter in A and 5B is larger, a problem occurs in which the left and right lenses collide with a circular lens. For this reason, the lenses used for the left and right separated imaging optical systems 5A and 5B need to be not only simple circles but also lenses having a part cut off on the left and right facing sides. Specifically, it is desirable to straighten the outer peripheral portion of the lens on the side where a mechanical obstacle occurs as shown in FIG. Although FIG. 4 shows only the first separation imaging lens system 5c, the same processing is performed on the second separation imaging lens system 5d.

An optical filter group 17 is arranged between the imaging devices 16A and 16B and the left and right separated imaging optical systems 5A and 5B. The details include an infrared cut filter, a treatment laser beam cut filter (mainly a YAG laser), an optical low-pass filter (mainly quartz), and the like.

Next, the optical adjustment when the scope section 12a or 12b and the camera head section 13 are separated at the boundary between the relay optical system 3 and the separation imaging optical system 5 will be described. FIG.
In the configuration shown in FIG. 1, a plurality of scope parts 12a or 12b are attached to one camera head part 13 for use.
It is important to ensure the optical compatibility of each system. For that purpose, the following adjustment mechanism is required as optical adjustment at the time of product assembly.

The focus adjusting mechanism of the scope section 12a or 12b (movement of the lens in the optical axis direction in the relay optical system 3,
Alternatively, the focus adjustment mechanism of the camera head 13 (movement of the lens in the direction of the optical axis in the separation imaging optical system 5, or adjustment of the image sensor 1)
6A, 16B in the optical axis direction) Image sensors 16A, 16B in the camera head unit 13
Adjustment of Eccentricity by Position Movement in a Plane Perpendicular to the Optical Axis of the Camera Head Unit 13
Adjustment of rotation direction in a plane perpendicular to the optical axis of the scope unit 12a unless the adjustment mechanism described above is provided.
Or, it is difficult to ensure optical compatibility when separating the camera head unit 13 from the camera head unit 13 and the scope unit 12a or 12b
It becomes difficult to perform good stereoscopic observation only by connecting the camera head 13 to the camera head 13, which is inconvenient for the user.

In the schematic diagram of the optical system shown in FIG. 3A, the portions after the relay optical system, which are the major features of this embodiment, are shown using the lens power arrangement. In FIG. 3A, a thick arrow indicates a real image, and a thin arrow having arrows at both ends indicates a positive power by the lens.
The light flux exiting the object 1 passes through the objective optical system 2 and the relay optical system 3, and forms a relay final image 4. The relay final image 4 is just one real image that is not separated left and right.

The luminous flux leaving the relay final image 4 is incident on the separation imaging optical systems 5A and 5B comprising two optical axes independent of the right and left, and the luminous flux forming the left and right images is completely separated there. Normally, a brightness stop 6 is provided before, after or inside the separation imaging optical systems 5A and 5B. The light beams that have passed through the separation imaging optical systems 5A and 5B are imaging plane images 7A and 7 which are two real images independent of left and right.
Form B. By arranging the imaging planes of the imaging devices 16A and 16B at the positions of the imaging plane images 7A and 7B, it is possible to capture left and right object images having parallax.

The length in the optical axis direction on the hand side is the final image 4 of the relay.
Depends on the distance L between the image plane images 7A and 7B, and the distance L
The smaller is, the shorter the hand side is, which is desirable. L from specification
Let Le be the estimated value of Le in the configuration of the first embodiment.
Is obtained by the following equation.

Le = D (1−β) / | 2 (tan θ−β tan θ ′) | (1) In the case of θ ′ = θ in the equation (1), Le = D / | 2 tan θ | (2) In the case of θ ′ = 0 ° in the equation (1), Le = D (1−β) / | 2tan θ | (3) Here, θ and θ ′ are emitted from the center of the relay final image 4,
Separated imaging optical system 5 passing through the center of the left and right apertures of aperture stop 6
The incident angles and the exit angles of the principal rays of A and 5B, and D are the imaging plane image 7.
A distance between the central axes of A and 7B and β are paraxial lateral magnifications of images in the optical system from the relay final image 4 to the imaging plane images 7A and 7B. In the configuration of this embodiment, β is the separation imaging optical system 5A,
The paraxial lateral magnification is 5B. Θ and θ ′ are both positive.

Of the parameters in equation (1), θ, D,
β is approximately determined according to the design specifications. The choice of the incident angle θ affects the three-dimensional effect, but it is necessary to fully utilize the numerical aperture of the relay optical system 3 in order to increase the three-dimensional effect. It is determined according to.

In order to reduce the width at the hand side, it is necessary to select a small value for the center axis interval D so that the packages of the left and right image sensors 16A and 16B do not collide with each other. The paraxial lateral magnification β is determined according to the imaging devices 16A and 16B to be used.

As described above, if the numerical aperture of the relay optical system 3 and the imaging devices 16A and 16B are determined, the possible values of θ, D, and β are almost determined. Therefore, the only parameter having the degree of freedom left in equation (1) is the emission angle θ ′.

In equation (1), it can be seen that the larger the emission angle θ ', the smaller the estimated value Le can be. For reference θ '=
Comparing Expression (2) for θ and Expression (3) for θ ′ = 0 °, the estimated value Le is always smaller in Expression (2) than in Expression (3). In particular, in the case of an enlarged system of β ≦ −1, a difference of more than twice occurs.

In the configuration of this embodiment, the separation and imaging optical systems 5A and 5B are arranged immediately after the relay final image 4, and the light is emitted from the center of the relay final image 4 and passes through the center of the left and right apertures of the aperture stop 6. By making the chief rays of the imaging optical systems 5A and 5B emit obliquely, the estimated value Le is reduced and the length on the hand side is reduced.

Next, for comparison, the estimated value Le in the conventional configuration will be described. FIG. 3B shows a configuration of a conventional example G92217980, which is an optical system 10 for expanding the axial interval.
It is a schematic diagram of an optical system in a configuration in which A 'and 10B' are deleted. FIG. 3 (a) from the object 1 to the final relay image 4 '.
However, the optical system thereafter is significantly different.

The luminous flux leaving the relay final image 4 'is converted into a parallel luminous flux by an infinity imaging optical system 9 coaxial with the relay optical system 3'. The parallel luminous flux passes through a separate imaging optical system 5 'and a brightness stop 6' composed of two left and right independent optical axes, and forms two left and right independent real imaging plane images 7A 'and 7B'.
In the case of this configuration, the estimated value Le is expressed by the above-described equation (3) because θ ′ = 0 °.
Note that the paraxial lateral magnification β in the case of FIG. 3B is β = −fb / fa, where fa is the focal length of the imaging optical system 9 at infinity and fb is the focal length of the separation imaging optical system 5 ′. In a relationship.

Under the condition that the numerical aperture of the relay optical system 3 'and the image pickup device are the same, and the values of θ, D and β are the same, the expression (3) according to the configuration of the conventional example described above and the configuration of the present embodiment are used. When the equation (1) is compared, the estimated value Le according to the equation (1) in the present embodiment is smaller, and the length on the hand side can be reduced. A calculation example based on data of the present embodiment described below is as follows.

Θ = 7.12 ° D = 16.08 [m
m] β = −1.02 θ ′ = 2.85 ° From equation (1), in this embodiment, Le = 92.44 [m
m] From equation (3), in the conventional example, Le = 130.02 [m
m] In the above data, the estimated value Le according to the configuration of the present embodiment is about 38 mm shorter than the estimated value Le according to the configuration of the conventional example, and this difference is very large.

In the configuration of this embodiment, the emission angle θ 'is intentionally
Is increased instead of 0 ° to reduce the hand-side length. However, when a color solid-state imaging device that is widely used as an imaging device is used, if the emission angle θ ′ is too large, color shading is performed. Problem arises. Although the degree of occurrence of color shading differs for each solid-state imaging device, there is a high possibility that a problem will occur if the emission angle θ ′ greatly exceeds 3 °. Therefore, in the data of the first embodiment, the occurrence of color shading is prevented by keeping θ ′ = 3 ° or less.

Further, in this embodiment, as shown in FIG. 1, a stereoscopic endoscope 11 is provided with a scope section 12a having an insertion section 14.
Or 12b and a camera head 13. These are mechanically connected during use. Merits of separating the scope section 12a or 12b and the camera head section 13 include the following points.

A plurality of scope units having different specifications (for example, those having different viewing directions and outer diameters of the insertion portion) can be prepared, and a suitable one can be selected and used. In this case, only one camera head is required. (Integration increases the cost burden for the user.) The electronic part and the scope part having no mechanically movable part may enable sterilization by an autoclave. (It is difficult to obtain autoclave resistance when integrated.) Among the above advantages, it is particularly important to be able to select scope sections having different viewing directions. FIG. 1 shows that a direct-view scope 12a and a perspective scope 12b can be connected to one camera head 13. still,
When the oblique scope section 12b is used, the insertion section 14 is frequently rotated to widen the observation field of view.

At this time, if the scope section 12b and the camera head section 13 rotate in synchronization, the observation image also rotates, so that it is very difficult to perform the treatment. For this reason, the camera head unit 13
It is desirable that the connection between the and the scope unit 12a or 12b be relatively rotatable about the optical axis of the relay optical system 3 of the scope unit 12a or 12b. That is, it is preferable that the scope section 12a or 12b can be freely rotated even when the camera head section 13 is spatially fixed. If the advantages described above are not so important, the optical system may be configured as an integral type, and the configuration of the optical system according to the first embodiment can correspond to any product configuration.

The lens data of this embodiment is described below. Since the optical system of this embodiment includes an eccentric optical system as described above, the lens data is mounted by dividing the relay final image 4 into two parts. It is not necessary to associate the following two divisions of data with the separation of the scope unit and the camera head unit in the product configuration, and the mechanical separation in the product configuration may be determined separately from this division. Lens Data of Objective Optical System 2 to Relay Final Image 4 of First Embodiment> Surface Number (K) Radius of Curvature (R) Surface Spacing (S) Refractive Index (N) Abbe Number (ν) ------ −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− 1 ∞ 0.4000 1.76820 71.79 2 ∞ 0.2000 1.00000 3 ∞ 0.8000 1.78472 25.76 4 (Aspherical surface) 5.0000 1.4000 1.00000 5 ∞ 21.5700 1.88300 40.78 6 ∞ 5.6000 1.88300 40.78 7 -8.3140 1.1000 1.00000 8 -6.2590 1.0000 1.57501 41.49 9 9.4380 3.5000 1.88300 40.78 10 -28.6400 0.7000 1.00000 11 ∞ 11.5000 1.88300 40.78 12 -14.1320 1.3000 1.00000 13 -12.925 1.7000 1. 14 5.8830 5.3000 1.48749 70.21 15 -13.3400 0.3000 1.00000 16 27.1360 10.2000 1.88300 40.78 17 -13.7980 1.2000 1.80518 25.43 18 -90.6670 5.0000 1.00000 19 ∞ 5.0000 1.00000 20 18.7500 34.0200 1.62004 36.25 21 -7.7830 1.9800 1.80518 25.43 22 -24.3640 0.5000 1.0000 23. 36.25 24 -26.1580 0.5000 1.00000 25 24 .3640 1.9800 1.80518 25.43 26 7.7830 34.0200 1.62004 36.25 27 -18.7500 10.0000 1.00000 28 18.7500 34.0200 1.62004 36.25 29 -7.7830 1.9800 1.80518 25.43 30 -24.3640 0.5000 1.00000 31 26.1580 20.0000 1.62004 36.25 32 -26.1580 0.5000 1.00000 33 24.3640 25.800 1.605 36.25 35 -18.7500 10.0000 1.00000 36 18.7500 34.0200 1.62004 36.25 37 -7.7830 1.9800 1.80518 25.43 38 -24.3640 0.5000 1.00000 39 26.1580 20.0000 1.62004 36.25 40 -26.1580 0.5000 1.00000 41 19.3750 3.0000 1.88300 40.78 42 ∞ 1.5000 1.72825 28.46 43 8.68202.4200 1.00000 3.00000 49.60 45 19.0720 20.7800 1.00000 46 16.6190 4.0000 1.88300 40.78 47 135.1380 6.0000 1.00000 48 ∞ Aspherical surface (4th surface) P = 1 E = −0.53376 × 10 ＾ (− 3) F = −0.80576 × 10 ＾ (− 4) G = 0.93333 × 10 ＾ (− 5)

[Specifications and other data] Object distance -40 Brightness aperture position (exit pupil position) 32 from final plane (48 planes) Final relay image height 4.08 Final objective image height 3.5 Effective lens diameter φ9. 2F no. 3.166 Angle of view 65.2 ° Inward angle at object distance of −40 (angle between left and right stereoscopic axes on object side) 2.06 ° Focal length -6.806 Distortion (maximum image height) -2.88 %

<Lens Data of Relay Final Image 4 to Separated Imaging Optical System 5> Surface Number (K) Radius of Curvature (R) Surface Spacing (S) Refractive Index (N) Abbe Number (ν) ------ −−−−−−−−−−−−−−−−−−−−−−−−−−−−−− 1 1 25.3000 1.00000 2 ∞ 3.0000 1.7682 71.79 3 ∞ 5.0000 1.00000 4 (brightness aperture) ∞ 10.0000 1.00000 5 ∞ 1.0000 1.51633 64.15 6 ∞ 2.0000 1.00000 7 -75.4950 1.5000 1.78472 25.71 8 18.7500 9.7100 1.77250 49.60 9 -27.9810 5.0000 1.00000 10 45.2840 4.0000 1.77250 49.60 11 -45.2840 12.9700 1.00000 12 -19.1790 1.5000 1.66680 33.04 13 -112.7350

[Specifications / Other Data] Applicable imaging device imaging surface size 1/2 inch CCD vertical 4.9 × horizontal 6.6 paraxial image magnification β−1.02 Bright aperture opening diameter φ2.8 F no. 11.7 Optical axis interval d 8 of separation imaging optical system Center axis interval D 16.08 Focal length 23.147 Distance L from final relay image to image plane image 109.
35 θ = 7.12 ° θ ′ = 2.85 ° (1) Equation Le = 92.44 [Equation (2) Le = 64.37] [Equation (3) Le = 13.002] In the above data, Has an aspheric surface, and its definition will be described. The aspherical surface used in this specification is defined by the following equation according to the YZ coordinate system shown in FIG.

Z = (Y ＾ 2 / R) / (1 + {(1−PY ＾ 2 / R ＾)
2) + EY ＾ 4 + FY ＾ 6 + GY ＾ 8 where R is the paraxial radius of curvature of the aspheric surface, P is the parameter that determines the shape of the quadric surface term, and E, F, and G are the fourth and sixth, respectively.
These are the next and eighth order aspherical coefficients, and the sign of the Z axis is positive in the image side. Here, for example, √ (J) represents the square root of J, and Y ＾ 2 represents the square of Y.

In the above data, the distance L from the actual final image of the relay to the imaging plane image is 109.35 mm, and the estimated Le in equation (1) is 92.44 mm. L is larger than Le, but this difference is due to the influence of the principal point spacing due to the power arrangement of the individual lenses in the actual design of the separation imaging optical system 5 and the influence of the surface spacing increase due to the presence of the glass medium. It is inevitable that L> Le.

The first embodiment described so far assumes an abdominal endoscope (abbreviated as a laparoscope) which is used by inserting it into the abdomen. Therefore, the relay optical system 3 is designed with a large effective lens diameter. are doing.

A configuration that is desirably added to the basic configuration of this embodiment will be described. In the above description, various detailed configurations have been described based on the present embodiment. Here, as a summary of those, a configuration that is desirable to be added to the basic configuration is organized and described.

(1) The optical axis of the objective / relay optical system, the optical axis of the separated imaging optical system, and the central axis of the imaging plane are parallel, and the interval between the optical axes of the separated imaging optical system is smaller than the interval of the central axis of the imaging plane. (2) In (1), in order to prevent collision between the peripheral portions of the lenses of the left and right separated imaging optical systems, the separated imaging optical system includes a lens whose outer peripheral portion has a shape other than a circle.

(3) It is composed of a scope unit and a camera head unit. The scope unit includes an objective optical system and a relay optical system, and the camera head unit includes a separate imaging optical system and an imaging device. (4) In (3), the scope unit can rotate with respect to the camera head unit using the optical axis of the relay optical system as the rotation axis. (5) In (4), the scope section has a brightness stop near the connection section with the camera head section, and when the scope section and the camera head section are connected, the brightness stop is synchronized with the camera head section. And is not synchronized with the rotation of the scope. (6) An optical system for expanding the axial interval is not included between the relay final image and the separation imaging optical system.

In this embodiment, in consideration of the easiness of optical / mechanical design, the optical axes are all designed to be parallel. Although a design in which these are not parallel can be considered, it is not preferable because problems such as the necessity of an optical device for correcting an inclined image plane and the complicated processing of mechanical parts occur. Further, in addition to the above, the emission angle θ ′ is made positive by shortening the optical axis interval d of the separation imaging optical system with respect to the imaging surface center axis interval D. When this relationship is reversed, the emission angle θ 'becomes negative, and the estimated value Le cannot be shortened, but instead increases.

The first embodiment eliminates the need for an optical system for expanding the shaft interval, thereby reducing the number of adjustment points for variations.
Incident angle θ of chief ray using separation imaging optical systems 5A and 5B
The light is guided obliquely rearward along the principal ray having the same sign as that of (> 0) at the emission angle θ ′ (> 0), and is further decentered left and right with respect to the optical axes Oa and Ob of the separation imaging optical systems 5A and 5B (imaging). Image sensor 16A, 1 on which the center axes 17a, 17b) of the surfaces are arranged
By separating and forming an image on 6B, the length of the optical system on the hand side in the optical axis direction can be reduced.

Next, a second embodiment of the present invention will be described. FIG.
Shows a schematic diagram of the optical system of the second embodiment, and FIG. 7 shows a configuration of the optical system on the hand side. This embodiment is different from the first embodiment in that
Further, it is configured to avoid the occurrence of color shading while shortening the length on the hand side.

For this reason, as shown in FIG. 6, the separation imaging optical systems 5A and 5B and the imaging surface images 7 on the imaging elements 16A and 16B are used.
An oblique incidence suppressing optical element 8 for reducing the inclination of a light beam incident on the imaging elements 16A and 16B from the separation imaging optical systems 5A and 5B is provided between A and 7B.

Incidentally, the oblique incidence suppressing optical element 8 is used to
It is desirable to dispose them in the vicinity of A and 7B, so that the oblique incidence suppressing effect can be obtained without substantially affecting Le.

As the oblique incidence suppressing optical element 8, FIG.
As shown in (a), it is desirable to use a positive power field lens 18 having an optical axis at the center of the two imaging plane central axes. Further, as shown in FIG. 7B, a refractive prism 19 having a wedge angle may be used. Since the oblique incidence suppressing optical system element 8 only needs to be capable of reducing the angle of oblique incidence, complicated optical adjustment such as an optical system for expanding the axial interval is not required, and the optical adjustment is not complicated. . If the oblique incidence suppressing optical element 8 is used, the emission angle θ ′ can be further increased, and the estimated value Le can be further reduced.

In the second embodiment, the estimated value Le of the distance of the optical system at hand is shorter than in the first embodiment, and the occurrence of color shading can be avoided. The other effects are the same as those of the first embodiment.

In other words, although the configurations which are desirable to be added to the basic configuration in the first embodiment have been described in (1) to (6), this embodiment has the following large functions in addition to these. (7) An oblique incidence suppressing optical element is provided between the separation imaging optical system and the imaging element, and reduces the inclination of a light beam entering the imaging element from the separation imaging optical system.

In the above embodiment, the lens diameter of the optical system is determined assuming a laparoscope. However, in other applications (arthroscope, bladder / urethroscope, rigid endoscope for brain surgery, etc.), the lens effective diameter is smaller. Design is required.

In this case, the numerical aperture of the relay optical system 3 becomes small, and the distance between the optical axes of the separation and imaging optical systems 5A and 5B must be narrower than in the first embodiment. Processing may be difficult.

For this purpose, the relay optical system 3 may be constituted by using anamorphic lenses having different imaging magnifications in the horizontal direction (horizontal direction) and the vertical direction (vertical direction). In other words, by adopting a lens system that transmits an image by compressing in the left-right direction more than in the vertical direction, the numerical aperture in the left-right direction can be substantially increased. Then, an image compressed in the left-right direction is expanded and formed by an expanding anamorphic lens system provided near the final lens of the relay optical system 3. The expanded image is regarded as the final image of the relay optical system, and is formed on the image sensor by the separation imaging optical systems 5A and 5B as in the first embodiment or the second embodiment. Note that an anamorphic lens system that forms an image by compressing the objective optical system in the horizontal direction rather than the vertical direction may also be used.

In a small-diameter stereoscopic rigid endoscope, if an anamorphic lens system is not adopted, there is a case where it is not possible to omit the axial spacing expanding optical system which is another object of the present invention. Occurs. FIGS. 8A and 8B show a hand-side optical system according to a third embodiment of the present invention, which is obtained by adding an axial interval expanding optical system to the basic configuration of the first embodiment. An optical axis expansion optical system 20 is arranged between the imaging optical systems 5. FIG. 8A shows the use of a parallelogram prism 22 that reflects twice as the axial spacing enlargement optical system 20, and FIG. 8B shows the refractive prism 2 having a large thickness in the left-right direction.
3 is used.

At this time, it is desirable to separate the right and left light beams on the incident surface of the axially enlarged optical system 20, and it is preferable that the aperture stop 6 is disposed in the vicinity thereof. As described above, the third embodiment cannot achieve the second object of the present invention (that is, at the expense of the labor of right and left optical adjustment), but gives priority to the narrow system of the insertion portion, and in the basic configuration of the present invention. An axial spacing expansion optical system 20 may be arranged in front of the separation imaging optical system 5.

Also in this case, the separation imaging optical system 5
A, 5B are guided obliquely rearward along the principal ray having the same sign as the incident angle of the principal ray to the separated imaging optical system 5.
Imaging elements 16A, 16 in which the eccentricity (the center axis of the imaging surface) is further deviated left and right from the optical axes Oa, Ob of A, 5B.
The image is separated and image-formed on B. For this reason,
As compared with the conventional example under the same conditions including the axial spacing expanding optical system, the present embodiment can shorten the length of the optical system on the hand side. That is, the first object has been achieved. Note that the image sensor is not limited to one using two image sensors, and may be one that forms two images on one image surface.

[Supplementary Notes] (1) The separation imaging optical system emits along the principal ray at an exit angle having the same sign as the incident angle of the principal ray incident from the final image of the relay optical system, and has parallax with each other. 2. The stereoscopic rigid endoscope according to claim 1, wherein the image is separated into two images.

[0083]

As described above, according to the present invention, an insertion portion to be inserted into a subject, and an objective optical system arranged at the distal end of the insertion portion and having one optical axis for forming an image of an object. Having a common optical axis with the objective optical system, and a relay optical system for transmitting an image formed by the objective optical system in the proximal direction, and having two optical axes, and A separation imaging optical system that guides a light beam from a final image formed on the hand side of the relay optical system to an obliquely rear side and separates and forms two images having parallax from each other; And the image sensor that captures the right and left images is provided, so that the length of the optical axis in the hand side can be shortened without using an optical axis expansion optical system that expands the optical axis interval on the image sensor side, and the operation can be performed. An easily miniaturized stereoscopically rigid endoscope can be realized. In addition, right and left optical adjustment is easy.

[0084]

[Brief description of the drawings]

[0085]

FIG. 1 is a schematic configuration diagram of a stereoscopic rigid endoscope according to a first embodiment of the present invention.

[0086]

FIG. 2 is a specific configuration diagram of an optical system of the stereoscopic rigid endoscope according to the first embodiment.

[0087]

FIG. 3 is a schematic diagram functionally showing the optical system of FIG. 2;

[0088]

FIG. 4 is a perspective view showing a part of a separation imaging optical system.

[0089]

FIG. 5 is an explanatory diagram showing a coordinate system of an aspheric surface.

[0090]

FIG. 6 is a schematic diagram functionally showing an optical system according to a second embodiment of the present invention.

[0091]

FIG. 7 is a specific configuration diagram of a separation imaging optical system having an oblique incidence suppression optical element.

[0092]

FIG. 8 is a specific configuration diagram of a separation imaging optical system according to a third embodiment of the present invention.

[0093]

FIG. 9 is an overall configuration diagram of an endoscope system in a conventional example.

[0094]

FIG. 10 is a schematic configuration diagram of a conventional optical system.

[0095]

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Object 2 ... Objective optical system 3 ... Relay optical system 4 ... Final image 5A, 5B ... Separation imaging optical system 6 ... Aperture 7A, 7B ... Imaging surface image 11 ... Stereoscopic rigid endoscope 12a, 12b ... Scope part 13 ... Camera head section 14 ... Insertion section 15 ... Grip section 16A, 16B ... Imaging element 17a, 17b ... Center axis O, Oa, Ob ... Optical axis d ... Optical axis interval D ... Center axis interval L ... Distance θ ... Incident angle θ '... Emission angle

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) A61B 1/00-1/32 G02B 23/24-23/26 G03B 35/00-35/26

Claims (8)

(57) [Claims] 1. An insertion unit to be inserted into a subject, an objective optical system disposed in a distal end of the insertion unit, having an optical axis to form an image of an object, and an objective optical system. A relay optical system having a common optical axis and transmitting an image formed by the objective optical system in a proximal direction; and a relay optical system having two optical axes and a proximal side of the relay optical system. A separation imaging optical system that guides the light flux from the final image formed diagonally to the rear side, separates and forms two images having parallax, and captures the separated left and right images. A stereoscopic rigid endoscope comprising: an imaging element; 2. The stereoscopic vision according to claim 1, further comprising: an oblique incidence suppressing optical element disposed between the separation imaging optical system and the imaging element, for reducing a tilt of a light beam entering the imaging element from the separation imaging optical system. Rigid endoscope. 3. The optical axis of the objective optical system and the relay optical system,
The optical axis of the separation imaging optical system and the center axis of the imaging surface of the imaging device are parallel, and the optical axis interval of the separation imaging optical system is smaller than the interval of the imaging surface center axis. Stereoscopic rigid endoscope. 4. The separated imaging optical system according to claim 3, wherein the separated imaging optical system includes a lens whose outer peripheral portion has a shape other than a circle in order to prevent collision between peripheral portions of the lenses of the left and right separated imaging optical systems. Stereoscopic rigid endoscope. 5. A camera comprising a scope unit and a camera head unit, wherein the scope unit includes an objective optical system and a relay optical system, and the camera head unit includes a separation imaging optical system and an image sensor. Item 3. A stereoscopic rigid endoscope according to item 1 or 2. 6. The stereoscopic rigid endoscope according to claim 5, wherein the scope section is rotatable with respect to the camera head section around the optical axis of the relay optical system as a rotation axis. 7. The scope section has a brightness stop near a connection portion with the camera head section, and when the scope section and the camera head section are connected, the brightness stop is fixed in synchronization with the camera head section. 7. The stereoscopic rigid endoscope according to claim 6, wherein the endoscope is not synchronized with the rotation of the scope. 8. The optical system according to claim 1, further comprising an optical axis expansion optical system between the relay final image and the separation imaging optical system.
The stereoscopic rigid endoscope according to the above.