JP6713386B2 - Objective optical system for stereoscopic endoscope, stereoscopic endoscope, and imaging device for stereoscopic endoscope - Google Patents

Description

The present invention relates to an image pickup device for a stereoscopic endoscope.

The strabismus endoscopes are disclosed in Patent Documents 1 to 3. The oblique-viewing endoscope of Patent Document 1 has a front group, a visual field direction conversion element, a rear group, and an imaging element. The visual field direction conversion element is arranged between the front group and the rear group.

The perspective endoscope of Patent Document 2 is an endoscope capable of stereoscopic viewing. In the perspective endoscope of Patent Document 2, an objective optical system, a relay optical system, and a primary imaging optical system are arranged on a common optical path. The objective optical system has a perspective prism optical system.

Two optical paths are formed on the image side of the common optical path. An aperture, a secondary imaging optical system, and an image sensor are arranged in each optical path. The two openings are formed in one plate-shaped member.

The perspective endoscope of Patent Document 3 is an endoscope capable of stereoscopic viewing. In the perspective endoscope of Patent Document 3, only two optical paths are formed. A front group, a reflecting member, and a rear group are arranged in each optical path. The reflecting member for one optical path and the reflecting member for the other optical path are configured by one member.

Usually, light enters the optical system from various directions. Part of the incident light is reflected inside the lens frame. The reflected light travels in various directions depending on the reflection direction and the number of reflections. Of these, part of the reflected light goes to the image position.

Reflected light (hereinafter referred to as “stray light”) traveling toward the image position may be in a divergent state or a converged state at the image position. Stray light is also called flare, ghost, etc. and is not necessary for the image of the original object. Therefore, when the stray light overlaps the optical image, the contrast and resolution of the optical image decrease.

When the optical system has only one optical path, one optical image is formed. In an optical system with only one optical path, the contrast and resolution of the optical image do not decrease unless stray light overlaps the optical image.

When the optical system has two optical paths, two optical images are formed. In an optical system having two optical paths, if the stray light generated in one optical path does not overlap one optical image, the contrast or resolution of one optical image does not decrease.

However, in an optical system with two optical paths, the other optical path is located next to one optical path. Therefore, in some cases, the stray light generated in one optical path enters the other optical path. At this time, even if stray light is incident on the other optical path, the contrast and resolution of the other optical image do not decrease unless the stray light overlaps the other optical image. However, when the stray light overlaps with the other optical image, the contrast and resolution of the other optical image deteriorate.

Further, when stray light is generated in an image pickup apparatus for stereoscopic observation, the image of the stray light is often different between the left eye image and the right eye image. In particular, when stereoscopic observation is performed, if different images are displayed in the left-eye image and the right-eye image, a problem of causing great fatigue occurs.

Japanese Patent No. 5558058 JP, 7-236610, A JP 2006-317891 A

In the perspective endoscope of Patent Document 1, the optical system is configured by only one optical path. Therefore, the stray light generated in the optical system including only two optical paths is not taken into consideration.

In the perspective endoscope of Patent Document 2, the optical system includes a common optical path and two optical paths. Therefore, no consideration is given to stray light generated in an optical system having no common optical path, that is, stray light generated in an optical system having only two optical paths.

In the perspective endoscope of Patent Document 3, the optical system is composed of only two optical paths. However, stray light is not considered.

The present invention has been made in view of such problems, and in a stereoscopic endoscope in which an optical system is configured by only two optical paths, a stereoscopic objective optical system having an optical system with less stray light is provided. A system, a stereoscopic endoscope, and an imaging device for a stereoscopic endoscope are provided. Moreover, it aims at providing the stereoscopic endoscope and the imaging device for stereoscopic endoscopes which are easy to manufacture.

In order to solve the problems described above and achieve the object, an imaging device for a stereoscopic endoscope according to at least some embodiments of the present invention,
A first optical system disposed in the first optical path and generating a first optical image;
A second optical system arranged in the second optical path to generate a second optical image;
An image sensor for capturing the first optical image and the second optical image,
A parallel plate and an optical path conversion element are located in each of the first optical path and the second optical path,
The parallel plate and the optical path changing element are integrated,
The parallel plate is composed of a single member,
The predetermined position is an arbitrary position between the object side surface of the parallel plate and the image side surface of the optical path conversion element,
In the first optical system and the second optical system, the principal ray height of the off- axis light flux becomes the lowest at a predetermined position,
The first opening is located in the first optical path,
The second opening is located in the second optical path,
The first opening and the second opening are both located closer to the object side than the predetermined position or closer to the image side than the predetermined position ,
In position, characterized that you have been disposed aperture stop.
Further, the objective optical system for a stereoscopic endoscope according to at least some embodiments of the present invention,
A first optical system disposed in the first optical path and generating a first optical image;
A second optical system arranged in the second optical path to generate a second optical image,
A parallel plate and an optical path conversion element are located in each of the first optical path and the second optical path,
The parallel plate and the optical path changing element are integrated,
The parallel plate is composed of a single member,
The predetermined position is an arbitrary position between the object side surface of the parallel plate and the image side surface of the optical path conversion element,
In the first optical system and the second optical system, the principal ray height of the off-axis light flux becomes the lowest at a predetermined position,
The first opening is located in the first optical path,
The second opening is located in the second optical path,
The first opening and the second opening are both located closer to the object side than the predetermined position or closer to the image side than the predetermined position,
It is characterized in that an aperture stop is arranged at a predetermined position.
Further, the stereoscopic endoscope according to at least some embodiments of the present invention,
It is characterized by comprising the above-mentioned objective optical system for a stereoscopic endoscope.

According to the present invention, in a stereoscopic endoscope having an optical system with only two optical paths, an objective optical system for a stereoscopic endoscope having an optical system with less stray light, a stereoscopic endoscope, and a stereoscopic endoscope. It is possible to provide an imaging device for use. Further, it is possible to provide a stereoscopic endoscope and an imaging device for a stereoscopic endoscope that are easy to manufacture.

It is a figure which shows the structure and the stray light of the imaging device for stereoscopic endoscopes of this embodiment. It is a figure which shows the example of arrangement|positioning of an opening part. It is a figure which shows another example of arrangement|positioning of an opening part. It is a figure which shows the specific example 1 of an opening part. It is a figure which shows the specific example 2 of an opening part. It is a figure which shows the specific example 3 of an opening part. It is a figure which shows the specific example 4 of an opening part. It is a figure which shows the specific example 5 of an opening part. It is a figure which shows the example of arrangement|positioning of an aperture stop. It is a figure which shows an optical path conversion element. It is sectional drawing of the optical system for stereoscopic endoscopes.

Hereinafter, embodiments and examples of the objective optical system for a stereoscopic endoscope, the stereoscopic endoscope, and the imaging device for a stereoscopic endoscope according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments and examples.

The image pickup apparatus for a stereoscopic endoscope according to the present embodiment is arranged in a first optical path to generate a first optical image, and a second optical path to generate a second optical image. A second optical system for generating, a first optical image, and an image sensor for capturing the second optical image, and a parallel plate and an optical path conversion on each of the first optical path and the second optical path. The element is located, and the parallel plate and the optical path conversion element are integrated, and the parallel plate is composed of a single member, and at a predetermined position, the object side surface of the parallel plate and the image of the optical path conversion element. It is an arbitrary position between the side surface, and in the first optical system and the second optical system, at a predetermined position, the chief ray height of the off- axis light flux becomes the lowest, and the first opening portion is In the optical path, the second opening is located in the second optical path, and the first opening and the second opening are both located closer to the object than the predetermined position, or the predetermined opening. It is characterized in that it is located closer to the image side than the position.

FIG. 1 is a diagram showing a configuration and stray light of an image pickup apparatus for a stereoscopic endoscope according to the present embodiment. In the imaging device for a stereoscopic endoscope of the present embodiment, the optical system has a first optical path OP1 and a second optical path OP2. However, the optical system does not have a common optical path.

The first optical system OBJ1 is arranged in the first optical path OP1. The first optical system OBJ1 forms a first optical image I1. The second optical system OBJ2 is arranged in the second optical path OP2. The second optical system OBJ2 forms a second optical image I2.

The first optical image I1 and the second optical image I2 are captured by the image sensor IS. In FIG. 1, the number of image pickup elements IS is one, but two image pickup elements may be used. When two image pickup elements are used, the first optical image I1 is picked up by one of the image pickup elements and the second optical image I2 is picked up by the other image pickup element.

The same optical system is used for the first optical system OBJ1 and the second optical system OBJ2. This optical system includes, in order from the object side, a negative lens L1, a positive lens L2, a negative lens L3, a parallel plate PL, an optical path conversion element PR, a positive lens L4, a negative lens L5, and a positive lens L6. With.

The positive lens L2 and the negative lens L3 are cemented. The negative lens L5 and the positive lens L6 are cemented. A cover glass C1 and a cover glass C2 are arranged on the image side of the positive lens L6. The cover glass C1 and the cover glass C2 are joined. The cover glass C2 is a cover glass of the image sensor IS.

The parallel plate PL and the optical path conversion element PR are integrated. The parallel plate PL is composed of a single member. Therefore, the parallel plate PL has such a size that it is located in both the first optical path and the second optical path.

The optical path conversion element PR may be composed of a single member or may be composed of two members. In the optical path conversion element PR, the first optical path and the second optical path are each bent.

As the optical path conversion element PR, for example, a right angle prism can be used. In this case, the optical path located on the image side of the optical path conversion element PR is formed in the direction orthogonal to the paper surface. For ease of viewing, FIG. 1 shows a state in which the optical path is not bent.

The stray light will be described. FIG. 1 shows a state of stray light. Here, the state of stray light is qualitatively shown. That is, refraction of light in the lens is not taken into consideration. Therefore, the stray light is drawn as a straight line.

In FIG. 1, the stray light is reflected twice on the inner surface of the lens frame BAL. However, in reality, the refraction by the lens occurs, so that the second reflection may not occur.

The stray light LB _flar incident on the first optical path OP1 reaches the point P _in1 on the inner surface of the lens frame BAL. The stray light LB _flar is reflected at the point P _in1 and reaches the point P _in2 on the inner surface of the lens frame BAL. The stray light LB _flar is reflected at the point P _in2 and overlaps with the second optical image I2.

When the stray light LB _flar is focused at the image position, the ghost overlaps the second optical image I2. When the stray light LB _flar is in a diffused state at the image position, flare overlaps the second optical image I2. In either case, in the second optical image I2, a decrease in contrast and a decrease in resolution occur.

In the first optical system OBJ1 second optical system OBJ2, at a predetermined position, the principal ray height of an off-axis light flux LB _Offax is lowest. The first optical system OBJ1 and the second optical system OBJ2 are so designed. The predetermined position is an arbitrary position between the object side surface of the parallel plate PL and the image side surface of the optical path conversion element PR.

If there is a predetermined position between the object side surface of the parallel plate PL and the image side surface of the optical path conversion element PR, the ray height at the parallel plate PL or the ray height at the optical path conversion element PR becomes low. Therefore, the parallel plate PL and the optical path conversion element PR can be downsized.

As shown in FIG. 1, in the range from the image side surface of the negative lens L3 to the object side surface of the parallel plate PL (hereinafter referred to as “range A”), the stray light LB _flar is the on-axis light beam LB _ax or the off-axis light beam LB _offax. Away from. Therefore, the stray light LB _flar can be shielded by providing the opening in the range A.

Similarly, the optical path conversion element range is also the image side of the image side surface of the PR (hereinafter, referred to as "range B") But stray LB _flar is separated from the axial beam LB _ax and Jikugaikotaba _LB offax. Therefore, by providing the opening in the range B, the stray light LB _flar can be shielded.

The stray light LB _flar is generated in both the first optical path OP1 and the second optical path OP2. Therefore, it is preferable that the openings are provided in both the first optical path OP1 and the second optical path OP2. That is, the first opening is located on the first optical path OP1 and the second opening is located on the second optical path OP2.

The range A is located closer to the object than the predetermined position. The range B is located closer to the image side than the predetermined position. Therefore, the first opening and the second opening may be located closer to the object side than the predetermined position or closer to the image side than the predetermined position.

In FIG. 1, dotted lines are drawn near the object side surface of the parallel plate PL and near the image side surface of the optical path conversion element PR. This dotted line is located closer to the object side than the predetermined position or closer to the image side than the predetermined position. Therefore, the first opening and the second opening may be located at the positions indicated by the dotted lines. By doing so, stray light can be shielded.

As a result, it is possible to realize an image pickup apparatus for a stereoscopic endoscope having an optical system with less stray light. Further, since stray light can be reduced, it is possible to reduce ghost and flare that are superimposed on the optical image. Therefore, it is possible to prevent a decrease in contrast and a decrease in resolution in the optical image.

Further, as described above, the parallel plate PL and the optical path conversion element PR are integrated. As an integration method, for example, there is joining. In joining, for example, an adhesive is used.

As described above, the optical path conversion element PR may be composed of a single member or may be composed of two members. When the optical path conversion element PR is composed of a single member, the optical path conversion element PR may be joined to the parallel plate PL.

When the optical path conversion element PR is composed of two members, the two members may be separately bonded to the parallel plate PL. Alternatively, after joining the two members, the joined two members may be joined to the parallel plate PL.

As shown in FIG. 1, the parallel plate PL and the optical path conversion element PR are incorporated in the lens frame BAL. If the parallel plate PL and the optical path conversion element PR are separately incorporated at the time of assembling into the lens frame BAL, adjustment becomes difficult.

Since the parallel plate PL is composed of a single member, the shape and size of the outer diameter can be freely set. Therefore, the outer diameter of the parallel plate PL can be made larger than that of the optical path conversion element PR.

At this time, the outer diameter of the parallel plate PL is made into a shape suitable for positioning and processed with high accuracy. Then, the parallel plate PL and the optical path conversion element PR are integrated. By doing so, the positioning with respect to the lens frame BAL can be performed only by the parallel plate PL. Therefore, it becomes easy to adjust the lens when it is installed in the lens frame BAL.

Further, in the method in which the parallel plate PL and the optical path conversion element PR are integrated in advance, since the lens frame BAL does not exist, the positions and inclinations of the parallel plate PL and the optical path conversion element PR can be easily measured. Therefore, the adjustment before joining becomes easy. As a result, errors during assembly can be reduced.

In the optical system of the endoscope, the size of the parallel plate PL and the size of the optical path conversion element PR are very small. Therefore, if the parallel plate PL and the optical path conversion element PR are integrated, the size of one component becomes large, which facilitates the handling. As a result, work efficiency during assembly can be improved.

As described above, in the imaging device for a stereoscopic endoscope according to the present embodiment, it is possible to reduce an error during assembly and improve work efficiency during assembly. Therefore, it is possible to provide an imaging device for a stereoscopic endoscope that is easy to manufacture.

Another method of integration is holding by a metal frame or a resin frame, for example. Even in this case, the same effect as the integration by joining can be obtained.

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, it is preferable that the first opening and the second opening are located closer to the object than the predetermined position.

Since light rays are incident from various directions from the object side, many light rays are reflected on the inner surface of the lens frame BAL located on the object side with respect to the predetermined position. Therefore, by arranging the opening portion closer to the object than the predetermined position, it is possible to adopt a configuration in which the reflected light (stray light) does not efficiently pass through the desired position or the reflected light is not generated. Therefore, it is possible to realize an image pickup apparatus for a stereoscopic endoscope having an optical system with less stray light. Further, it is possible to realize an imaging device for a stereoscopic endoscope that is easy to manufacture.

In the image pickup apparatus for a stereoscopic endoscope of the present embodiment, it is preferable that the first opening and the second opening are located on the object side surface of the parallel plate.

FIG. 2 is a diagram showing an arrangement example of the openings. As shown in FIG. 2, the position P1 is the position of the joint surface between the parallel plate PL and the optical path conversion element PR. In position P1, the principal ray height of an off-axis light flux LB _Offax is the lowest. Therefore, the position P1 is the predetermined position.

As described above, the first opening ST1 and the second opening ST2 may be located on the object side of the predetermined position or on the image side of the predetermined position. In FIG. 2, the first opening ST1 and the second opening ST2 are located closer to the object side than the position P1.

More specifically, the first opening portion ST1 and the second opening portion ST2 are located on the object side surface S _PLf of the parallel plate PL. By doing so, the stray light LB _flar reflected on the inner surface of the lens frame BAL can be _blocked by the first opening ST1.

The stray light LB _flar reflected on the inner surface of the lens frame BAL gradually approaches the optical axis until reaching the position P1. Therefore, as the positions of the first opening ST1 and the second opening ST2 approach the position P1, the opening diameter of the first opening ST1 and the opening diameter of the second opening ST2 gradually decrease.

The object side surface S _PLf of the parallel plate PL is located _closest to the position P1 and is a place where the first opening ST1 and the second opening ST2 can be physically provided. Therefore, it is preferable to position the first opening ST1 and the second opening ST2 on the object side surface S _PLf of the parallel plate PL.

By doing so, both the opening diameter of the first opening portion ST1 and the opening diameter of the second opening portion ST2 can be reduced. As the aperture diameter becomes smaller, the area for blocking the stray light LB _flar increases. As a result, more stray light LB _flar can be _blocked .

In the imaging device for a stereoscopic endoscope according to the present embodiment, it is preferable that the first opening and the second opening are located on the image side with respect to the predetermined position.

By doing so, it is possible to realize an image pickup apparatus for a stereoscopic endoscope having an optical system with less stray light. Further, it is possible to realize an imaging device for a stereoscopic endoscope that is easy to manufacture.

In the image pickup apparatus for a stereoscopic endoscope of the present embodiment, it is preferable that the first opening and the second opening are located on the image side surface of the optical path conversion element.

FIG. 3 is a diagram showing another arrangement example of the openings. As shown in FIG. 3, the position P1 is the position of the joint surface between the parallel plate PL and the optical path conversion element PR. In position P1, the principal ray height of an off-axis light flux LB _Offax is the lowest. Therefore, the position P1 is the predetermined position.

As described above, the first opening ST1 and the second opening ST2 may be located on the object side of the predetermined position or on the image side of the predetermined position. In FIG. 3, the first opening ST1 and the second opening ST2 are located closer to the image side than the position P1.

More specifically, the first opening ST1 and the second opening ST2 are located on the image side surface S _PRr of the optical path conversion element PR. By doing so, the stray light LB _flar reflected on the inner surface of the lens frame BAL can be _blocked by the first opening ST1.

On the image side from the position P1, the stray light LB _flar reflected on the inner surface of the lens frame BAL gradually moves away from the optical axis as the distance from the position P1 increases. Therefore, as the positions of the first opening portion ST1 and the second opening portion ST2 move away from the position P1, the opening diameters of the first opening portion ST1 and the second opening portion ST2 gradually increase. ..

The image side surface S _PRr of the optical path conversion element PR is located _closest to the position P1 and is a place where the first opening ST1 and the second opening ST2 can be physically provided. Therefore, it is preferable to position the first opening ST1 and the second opening ST2 on the image side surface S _PRr of the optical path conversion element PR.

By doing so, both the opening diameter of the first opening portion ST1 and the opening diameter of the second opening portion ST2 can be reduced. As the aperture diameter becomes smaller, the area for blocking stray light LB _flar increases. As a result, more stray light LB _flar can be _blocked .

The image pickup apparatus for a stereoscopic endoscope of the present embodiment further includes an opaque flat plate, the parallel flat plate is a colorless and transparent flat plate, and the first opening and the second opening are formed as an opaque flat plate. It is preferable that the holes are formed.

FIG. 4 is a diagram showing a specific example 1 of the opening. 4A shows the case where the opening is separated from the parallel plate, and FIG. 4B shows the case where the opening and the parallel plate are integrated.

When the parallel flat plate PL is a colorless and transparent flat plate, the parallel flat plate PL itself cannot block stray light. The optical path changing element PR is also a colorless and transparent element. Therefore, the optical path conversion element PR itself cannot block stray light. Therefore, by using the light shielding member 1, stray light can be shielded.

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, as shown in FIG. 4A, the light blocking member 1 is composed of an opaque flat plate 2. The opaque flat plate 2 is provided with a first opening 3 and a second opening 4. The first opening 3 and the second opening 4 are through holes formed in the opaque flat plate 2.

The first opening 3 and the second opening 4 may be located on the object side with respect to the predetermined position. The predetermined position is the position of the joint surface between the parallel plate PL and the optical path conversion element PR. Therefore, as shown in FIG. 4A, the light blocking member 1 is arranged at a position apart from the parallel plate PL.

The optical system of the endoscope is small and the total length of the optical system is very short. Therefore, the thickness of the opaque flat plate 2 is likely to be thin. If the thickness of the opaque flat plate 2 becomes too thin, it becomes difficult to hold the light shielding member 1 alone. Even if the light blocking member 1 can be held alone, it is difficult to accurately position the light blocking member 1 within the lens frame BAL.

Therefore, it is preferable to integrate the opaque flat plate 2 with the parallel flat plate PL. By doing so, the light shielding member 1 can be easily held and the light shielding member 1 can be accurately positioned. As a result, stray light can be shielded more accurately.

Further, the first opening 3 and the second opening 4 can be located on the object side surface of the parallel plate PL by the integration. Therefore, both the opening diameter of the 1st opening part 3 and the opening diameter of the 2nd opening part 4 can be made small. As a result, more stray light can be blocked.

The parallel plate PL is integrated with the optical path conversion element PR. Therefore, by integrating the light blocking member 1 with the parallel plate PL, the light blocking member 1, the parallel plate PL, and the optical path conversion element PR are integrated as shown in FIG. 4B. As a result, it is possible to realize an imaging device for a stereoscopic endoscope that is easy to manufacture.

FIG. 5 is a diagram showing a specific example 2 of the opening. 5A shows the case where the opening is separated from the optical path changing element, and FIG. 5B shows the case where the opening and the optical path changing element are integrated. The same configurations as those in FIG. 4A are denoted by the same reference numerals, and description thereof will be omitted.

The first opening 3 and the second opening 4 may be located on the image side with respect to a predetermined position. The predetermined position is the position of the joint surface between the parallel plate PL and the optical path conversion element PR. Therefore, as shown in FIG. 5A, the light blocking member 1 is arranged at a position away from the optical path conversion element PR.

As described above, the thickness of the opaque flat plate 2 tends to be thin. If the thickness of the opaque flat plate 2 becomes too thin, it becomes difficult to hold the light shielding member 1 alone. Even if the light blocking member 1 can be held, it is difficult to accurately position the light blocking member 1 within the lens frame BAL.

Therefore, it is preferable to integrate the opaque flat plate 2 with the optical path conversion element PR. By doing so, the light shielding member 1 can be easily held and the light shielding member 1 can be accurately positioned. As a result, stray light can be shielded more accurately.

Further, the first opening 3 and the second opening 4 can be located on the image side surface of the optical path conversion element PR by the integration. Therefore, both the opening diameter of the 1st opening part 3 and the opening diameter of the 2nd opening part 4 can be made small. As a result, more stray light can be blocked.

The optical path conversion element PR is integrated with the parallel plate PL. Therefore, by integrating the light blocking member 1 with the optical path conversion element PR, the light blocking member 1, the parallel plate PL, and the optical path conversion element PR are integrated as shown in FIG. 5B. As a result, it is possible to realize an imaging device for a stereoscopic endoscope that is easy to manufacture.

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, the parallel plate is a colorless and transparent plate, and the light blocking part, the first opening part, the first opening part, It is preferable that the second opening and the light shielding portion are formed of a light shielding material.

FIG. 6 is a diagram showing a specific example 3 of the openings. FIG. 6A is a front view of the opening, and FIGS. 6B and 6C are views showing the formation place of the opening.

When the parallel flat plate PL is a colorless and transparent flat plate, the parallel flat plate PL itself cannot block stray light. The optical path changing element PR is also a colorless and transparent element. Therefore, the optical path conversion element PR itself cannot block stray light. Therefore, stray light can be shielded by forming the light shielding area 10 on the parallel plate PL or forming the light shielding area 10 on the optical path conversion element PR.

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, as shown in FIG. 6A, in the light shielding area 10, the light shielding portion 11, the first opening portion 12, the second opening portion 13, Are formed. The light blocking portion 11 is made of a light blocking material. Examples of the method of forming the light shielding portion 11 include coating and vapor deposition. With the light-shielding region 10, the same effect as that of the light-shielding member 1 can be obtained.

The light shielding region 10 may be formed on the parallel plate PL or the optical path conversion element PR. In FIG. 6B, the light shielding area 10 is formed on the object side surface of the parallel plate PL. In FIG. 6C, the light shielding region 10 is formed on the image side surface of the optical path conversion element PR.

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, it is preferable that the parallel plate is formed of an opaque material, and the first opening and the second opening are holes formed in the parallel plate.

When the parallel flat plate PL is a colorless and transparent flat plate, the parallel flat plate PL itself cannot block stray light. The optical path changing element PR is also a colorless and transparent element. Therefore, the optical path conversion element PR itself cannot block stray light. Therefore, stray light can be shielded by forming the parallel plate PL with an opaque material.

FIG. 7: is a figure which shows the specific example 4 of an opening part. 7A is a front view of the opening, and FIG. 7B is a sectional view of the opening.

In the image pickup apparatus for a stereoscopic endoscope of the present embodiment, as shown in FIG. 7A, the light blocking member 20 is composed of a parallel plate PL. An opaque material is used for the parallel plate PL. The parallel plate PL is provided with a first opening 21 and a second opening 22.

As shown in FIG. 7B, the first opening 21 and the second opening 22 are through holes formed in the parallel plate PL. The same effect as that of the light blocking member 1 can be obtained by the light blocking member 20.

In the light blocking member 20, the refractive index between the object side surface and the image side surface is 1. When the parallel plate PL is a colorless and transparent plate, the refractive index between the object side surface and the image side surface is larger than 1. In this way, the light-shielding member 20 and the colorless and transparent flat plate have different optical path lengths.

The first optical system OBJ1 and the second optical system OBJ2 shown in FIG. 1 are optical systems which are based on the assumption that the parallel flat plate PL is a colorless and transparent flat plate. Therefore, the light blocking member 20 cannot be used in the first optical system OBJ1 and the second optical system OBJ2. A new optical system based on the use of the light blocking member 20 is required.

The image pickup apparatus for a stereoscopic endoscope according to the present embodiment has a third opening located in the first optical path and a fourth opening located in the second optical path. The fourth opening and the fourth opening are preferably located closer to the image side than the predetermined position.

As shown in FIG. 1, the places for arranging the openings for blocking stray light are present on both sides of a predetermined position. As described above, stray light can be shielded by positioning the opening on one side of the predetermined position. However, the openings may be located on both sides of the predetermined position.

Therefore, the third opening and the fourth opening are used. The third opening and the fourth opening are different from the first opening and the second opening. The first opening and the second opening are positioned closer to the object than the predetermined position, and the third opening and the fourth opening are positioned closer to the image than the predetermined position. By doing so, the openings can be positioned on both sides of the predetermined position.

The third opening is located in the first optical path and the fourth opening is located in the second optical path. The first opening and the third opening are located in the first optical path, and the second opening and the fourth opening are located in the second optical path.

As described above, in the imaging device for a stereoscopic endoscope according to the present embodiment, the number of openings located on the optical path increases. Therefore, stray light that could not be shielded by the first opening and the second opening can be shielded by the third opening and the fourth opening. As a result, more stray light can be blocked.

In the image pickup apparatus for a stereoscopic endoscope of the present embodiment, it is preferable that the third opening and the fourth opening are located on the image side surface of the optical path conversion element.

As shown in FIGS. 4A and 5B, places where the first opening and the second opening are arranged are on both sides of a predetermined position. As described above, stray light can be shielded by arranging the first opening and the second opening on one side of the predetermined position. However, the openings may be located on both sides of the predetermined position.

As described above, the image pickup apparatus for a stereoscopic endoscope according to the present embodiment has the third opening and the fourth opening. The third opening and the fourth opening are different from the first opening and the second opening. The first opening and the second opening are located on the object side surface of the parallel plate, and the third opening and the fourth opening are located on the image side surface of the optical path conversion element. By doing so, the openings can be positioned on both sides of the predetermined position.

Further, the first opening, the second opening, the third opening, and the fourth opening are located at positions closest to the predetermined position. Therefore, the opening diameter of the first opening, the opening diameter of the second opening, the opening diameter of the third opening, and the opening diameter of the fourth opening can be made smaller. As the aperture diameter becomes smaller, the area for blocking stray light increases. As a result, more stray light can be blocked.

The imaging device for a stereoscopic endoscope according to the present embodiment further includes an opaque flat plate, the parallel flat plate is a colorless and transparent flat plate, and the third opening and the fourth opening are formed as an opaque flat plate. It is preferable that the holes are formed.

FIG. 8 is a diagram showing a specific example 5 of the opening. FIG. 8A shows the case where the opening is separated from the parallel plate and the optical path conversion element, and FIG. 8B shows the case where the opening, the parallel plate and the optical path conversion element are integrated. There is. The same configurations as those in FIG. 4A are denoted by the same reference numerals, and description thereof will be omitted.

As described above, by locating the openings on both sides of the predetermined position, more stray light can be blocked. Specifically, the first opening and the second opening are located closer to the object side than the predetermined position, and the third opening and the fourth opening are located closer to the image side than the predetermined position. ..

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, as shown in FIG. 8A, the light blocking member 1 is located on the object side of the parallel plate PL, and the light blocking member 30 is located on the image side of the optical path conversion element PR. doing.

The light shielding member 30 is composed of an opaque flat plate 31. The opaque flat plate 31 is provided with a third opening 32 and a fourth opening 33. The third opening 32 and the fourth opening 33 are through holes formed in the opaque flat plate 31.

In the image pickup apparatus for a stereoscopic endoscope of the present embodiment, since the light blocking member 1 is located on the object side of the predetermined position and the light blocking member 30 is located on the image side of the predetermined position, it is positioned on the optical path. The number of openings is increased. Therefore, stray light that cannot be blocked by the light blocking member 1 can be blocked by the light blocking member 30. As a result, more stray light can be blocked.

As described above, the thickness of the opaque flat plate 2 tends to be thin. For this reason, the opaque flat plate 2 is preferably integrated with the parallel flat plate PL. Similarly, the thickness of the opaque flat plate 31 tends to be thin. For this reason, the opaque flat plate 31 is preferably integrated with the optical path conversion element PR.

By doing so, the light blocking member 1 and the light blocking member 30 can be easily held, and the light blocking member 1 and the light blocking member 30 can be accurately positioned. As a result, stray light can be shielded more accurately.

In addition, the first opening 3 and the second opening 4 can be positioned on the object side surface of the parallel plate PL by the integration, and the third opening 32 and the fourth opening 33 can be arranged in the optical path. It can be located on the image side of the conversion element PR. Therefore, the opening diameter of the first opening, the opening diameter of the second opening, the opening diameter of the third opening, and the opening diameter of the fourth opening can be made smaller. As the aperture diameter becomes smaller, the area for blocking stray light increases. As a result, more stray light can be blocked.

The optical path conversion element PR and the parallel plate PL are integrated. Therefore, by integrating the light blocking member 1 with the parallel plate PL and the light blocking member 30 with the optical path conversion element PR, as shown in FIG. 8B, the light blocking member 1, the parallel plate PL, the optical path conversion element PR. And the light shielding member 30 is integrated. As a result, it is possible to realize an imaging device for a stereoscopic endoscope that is easy to manufacture.

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, the light blocking portion, the third opening portion, and the fourth opening portion are formed on the image side surface of the optical path conversion element, and the light blocking portion is made of the light blocking material. It is preferably formed.

As shown in FIGS. 6A and 6C, a light-shielding material can be used to form a light-shielding portion and an opening on the image side surface of the optical path conversion element. In the light shielding area 10 shown in FIG. 6A, a light shielding portion 11, a first opening portion 12 and a second opening portion 13 are formed. If the first opening 12 is replaced with the third opening and the second opening 13 is replaced with the fourth opening, the light-shielding portion, the third opening, and the third opening on the image side surface of the optical path conversion element. 4 openings can be formed.

In the image pickup apparatus for a stereoscopic endoscope of the present embodiment, it is preferable that the aperture stop is arranged at a predetermined position.

The aperture stop has two openings. The entrance pupil is an image of the aperture stop formed by a lens on the object side of the aperture stop. Therefore, the imaging device for a stereoscopic endoscope according to the present embodiment has two entrance pupils. If the positions of the two entrance pupils vary, stereoscopic vision becomes difficult.

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, the aperture stop is arranged at a predetermined position. The predetermined position is between the object side surface of the parallel plate and the image side surface of the optical path conversion element. The parallel plate and the optical path changing element are integrated. Therefore, the aperture stop is located on the image side surface of the parallel plate.

On a parallel plate, light refraction occurs on the object side surface and the image side surface. However, the angle of the light ray incident on the object side surface and the angle of the light ray exiting from the image side surface are the same. That is, unlike the lens and the optical path changing element, the parallel plate does not have the refractive power for bending the light beam. Therefore, by arranging the aperture stop on the image side of the parallel plate, it is possible to significantly reduce the positional variation of the entrance pupil, as compared with the case of arranging the aperture stop on the image side of the optical path conversion element.

Further, since the parallel plate is composed of a single member, there is an effect that the variation of the parallel plate can be minimized as compared with the case where two parallel plates are used.

In the imaging device for a stereoscopic endoscope of the present embodiment, the aperture of the aperture stop is a hole formed in an opaque flat plate, and the aperture stop is located between the parallel flat plate and the optical path conversion element, It is preferable that the parallel plate, the aperture stop and the optical path changing element are integrated.

FIG. 9 is a diagram showing an arrangement example of the aperture stop. FIG. 9A shows the case where the opening is separated from the parallel plate and the optical path conversion element, and FIG. 9B shows the case where the opening, the parallel plate and the optical path conversion element are integrated. There is. The same configurations as those in FIG. 4A are denoted by the same reference numerals, and description thereof will be omitted.

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, as shown in FIG. 9A, the light blocking member 1 is located on the object side of the parallel plate PL, and the brightness between the parallel plate PL and the optical path conversion element PR is increased. The diaphragm 40 is located.

In FIG. 9A, for ease of viewing, the aperture stop 40 is located away from the parallel plate PL and the optical path conversion element PR. However, as described later, the parallel plate PL and the optical path conversion element PR are integrated. Therefore, in reality, the aperture stop 40 is in close contact with the parallel plate PL and the optical path conversion element PR.

The aperture stop 40 is composed of an opaque flat plate 41. The opaque flat plate 41 is provided with an opening 42 and an opening 43. The opening 42 and the opening 43 are through holes formed in the opaque flat plate 41.

As described above, the optical system of the endoscope is small and the total length of the optical system is very short. Therefore, like the opaque flat plate 2, the thickness of the opaque flat plate 41 is likely to be thin. If the thickness of the opaque flat plate 41 is too thin, it becomes difficult to hold the aperture stop 40 alone. Even if the aperture stop 40 can be held alone, it is difficult to accurately position the aperture stop 40 within the lens frame BAL.

In the imaging device for a stereoscopic endoscope according to the present embodiment, the aperture stop 40 is located between the parallel plate PL and the optical path conversion element PR. Moreover, the parallel plate PL and the optical path conversion element PR are integrated. Therefore, the aperture stop 40 is integrated with the parallel plate PL and the optical path conversion element PR so as to be sandwiched between the parallel plate PL and the optical path conversion element PR. As a result, the aperture stop 40 can be easily held, and the aperture stop 40 can be accurately positioned.

The image pickup apparatus for a stereoscopic endoscope according to this embodiment has two entrance pupils. If the positions of the two entrance pupils vary, stereoscopic vision becomes difficult. The variation of the positions of the two entrance pupils includes the variation of the position in the optical axis direction and the variation of the position in the plane orthogonal to the optical axis.

When the position of the opening 42 and the position of the opening 43 are different in the optical axis direction, the positions of the two entrance pupils also vary in the optical axis direction. In this case, stereoscopic vision becomes difficult.

In the image pickup apparatus for a stereoscopic endoscope of the present embodiment, the opening 42 and the opening 43 are formed as one flat plate. Further, the aperture stop 40 is integrated with the parallel plate PL. Therefore, the position of the opening 42 and the position of the opening 43 can be made substantially the same in the optical axis direction.

By doing so, it is possible to minimize the position error of the aperture stop 40 with respect to the optical system located on the object side of the aperture stop 40. As a result, variations in the positions of the two entrance pupils in the optical axis direction can be reduced.

Further, the parallax required for stereoscopic vision occurs in the direction orthogonal to the two optical axes. Therefore, the distance between the two entrance pupils in the direction orthogonal to the two optical axes (hereinafter referred to as “parallax direction”) is also important. If this interval deviates from the design value, sufficient parallax cannot be obtained, or parallax becomes too large, which makes stereoscopic vision difficult.

In the image pickup apparatus for a stereoscopic endoscope of the present embodiment, the opening 42 and the opening 43 are formed as one flat plate. In this case, the openings 42 and 43 can be formed so that the deviation from the design value is minimized as compared with the method of using two members having one opening on one flat plate. Therefore, it is possible to minimize the positional deviation in the plane orthogonal to the optical axis. As a result, it is possible to reduce variations in the positions of the two entrance pupils in the plane orthogonal to the optical axis.

Furthermore, it is not necessary to adjust the relative positions of the opening 42 and the opening 43 during assembly. Therefore, the error during assembly can be reduced.

Further, the aperture stop 40 is integrated with the parallel plate PL. As described above, since the parallel plate PL is composed of a single member, the shape and size of the outer diameter can be set freely. Further, the outer diameter of the parallel plate PL can be formed into a shape suitable for positioning, and the outer circumference and the optical surface can be processed with high accuracy.

Therefore, regarding the opening 42 and the opening 43, it is possible to reduce the error in the optical axis direction. As a result, it is possible to reduce variations in the positions of the two entrance pupils in the optical axis direction.

As described above, the opaque flat plate 2 is preferably integrated with the parallel flat plate PL. By doing so, the light shielding member 1 can be easily held and the light shielding member 1 can be accurately positioned. As a result, stray light can be shielded more accurately.

The optical path conversion element PR, the aperture stop 40, and the parallel plate PL are integrated. Therefore, by integrating the light blocking member 1 with the parallel plate PL, the light blocking member 1, the parallel plate PL, the aperture stop 40, and the optical path conversion element PR are integrated as shown in FIG. 9B. As a result, it is possible to realize an imaging device for a stereoscopic endoscope that is easy to manufacture.

As shown in FIG. 7B, when the parallel plate PL is made of an opaque material, the aperture stop 40 may be arranged on the image side of the parallel plate PL. The opening diameter of the first opening 21 and the opening diameter of the second opening 22 are larger than the opening diameter of the opening of the brightness diaphragm 40. Therefore, the through hole may be formed so that the diameter decreases from the object side surface to the image side surface.

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, the light blocking portion and the aperture portion of the aperture stop are formed on the image side surface of the parallel plate, and the light blocking portion on the image side surface of the parallel plate is formed of the light blocking material. Is preferably provided.

As shown in FIGS. 6A and 6B, a light blocking material and an opening can be formed on the object side surface of the parallel plate PL using a light blocking material. However, the surface on which the light-shielding portion and the opening can be formed is not limited to this surface. As a matter of course, the light blocking material and the opening can be formed on the image side surface of the parallel plate PL by using the light blocking material.

In the light shielding area 10 shown in FIG. 6A, a light shielding portion 11, a first opening portion 12 and a second opening portion 13 are formed. By replacing the first opening 12 and the second opening 13 with the aperture of the aperture stop, it is possible to form the light-shielding portion and the aperture of the aperture stop on the image side surface of the parallel plate PL.

In the image pickup apparatus for a stereoscopic endoscope of the present embodiment, a light blocking portion and an aperture portion of the aperture stop are formed on the object side surface of the optical path conversion element, and the light blocking portion on the object side surface of the optical path conversion element is It is preferably formed of a light shielding material.

As shown in FIGS. 6A and 6C, a light blocking material and an opening can be formed on the image side surface of the optical path conversion element PR using a light blocking material. However, the surface on which the light-shielding portion and the opening can be formed is not limited to this surface. As a matter of course, the light-shielding material can be used to form the light-shielding portion and the opening on the object side surface of the optical path conversion element PR.

In the light shielding area 10 shown in FIG. 6A, a light shielding portion 11, a first opening portion 12 and a second opening portion 13 are formed. By replacing the first opening 12 and the second opening 13 with the opening of the aperture stop, the light blocking portion and the opening of the aperture stop can be formed on the object side of the optical path conversion element PR. ..

In the image pickup apparatus for a stereoscopic endoscope according to the present embodiment, it is preferable that the optical path conversion element is composed of a single member.

FIG. 10 is a diagram showing an optical path changing element. The same numbers are given to the same configurations as those in FIG. 8B and FIG. 9B, and the description will be omitted.

In FIG. 8B and FIG. 9B, the optical path conversion element PR is composed of two members. On the other hand, in the image pickup apparatus for a stereoscopic endoscope of the present embodiment, as shown in FIG. 10, the optical path conversion element PR′ is composed of a single member.

Hereinafter, a case where the optical path changing element is composed of a single member and a case where the optical path changing element is composed of two members will be compared. A rectangular prism is used as the optical path changing element. In this case, the optical path conversion element has an entrance surface, a reflection surface, and an exit surface.

In addition, the first optical axis AX1f and the second optical axis AX2f are assumed to be parallel. The first optical axis AX1f is the optical axis of the first optical path on the object side of the optical path conversion element. The second optical axis AX2f is the optical axis of the second optical path on the object side of the optical path conversion element.

When the optical path changing element is composed of a single member, a single reflecting surface is located across the two optical paths. Therefore, both the first optical path and the second optical path are bent at the same reflecting surface.

The angle of the reflecting surface with respect to the entrance surface is the same at any position within the reflecting surface. In this case, the direction of the reflecting surface is the same at the position intersecting with the first optical axis AX1f and the position intersecting with the second optical axis AX2f.

As described above, the first optical axis AX1f and the second optical axis AX2f are parallel to each other. That is, the direction of the first optical axis AX1f and the direction of the second optical axis AX2f are the same. Therefore, the direction of the first optical axis AX1r and the direction of the second optical axis AX2r are also the same. The first optical axis AX1r is the optical axis of the first optical path on the image side of the optical path conversion element. The second optical axis AX2r is the optical axis of the second optical path on the image side of the optical path conversion element.

The distance between the incident surface and the reflective surface is the same in the first optical path and the second optical path. Therefore, the first optical axis AX1r and the second optical axis AX2r are located in the same plane parallel to the incident surface. That is, there is no shift in the direction orthogonal to the parallax direction between the position of the first optical axis AX1r and the position of the second optical axis AX2r.

As described above, when the optical path conversion element is composed of a single member, it is not necessary to adjust the orientation of the first optical axis AX1r or the orientation of the second optical axis AX2r. Further, there is no need to adjust the relative distance or relative position between the first optical axis AX1r and the second optical axis AX2r.

When the optical path changing element is composed of two members, the reflecting surface is located in each of the two optical paths. Therefore, the first optical path and the second optical path are respectively bent by different reflecting surfaces.

As described above, in a single member, the angle of the reflecting surface with respect to the entrance surface is the same at any position within the reflecting surface. However, one member and the other member do not necessarily have the same angle of the reflecting surface with respect to the incident surface. In this case, the direction of the reflecting surface is different between the position intersecting with the first optical axis AX1f and the position intersecting with the second optical axis AX2f.

As described above, the first optical axis AX1f and the second optical axis AX2f are parallel to each other. That is, the direction of the first optical axis AX1f and the direction of the second optical axis AX2f are the same. However, since the two members have different reflecting surface orientations, the first optical axis AX1r and the second optical axis AX2r have different orientations.

In addition, the distance between the incident surface and the reflecting surface is not necessarily the same in one member and the other member. In this case, the distance between the incident surface and the reflecting surface differs between the first optical path and the second optical path. As a result, the first optical axis AX1r and the second optical axis AX2r do not lie in the same plane parallel to the incident surface. That is, a shift in the direction orthogonal to the parallax direction occurs between the position of the first optical axis AX1r and the position of the second optical axis AX2r.

Thus, when the optical path conversion element is composed of two members, it becomes necessary to adjust the orientation of the first optical axis AX1r and the orientation of the second optical axis AX2r. Further, it becomes necessary to adjust the relative distance and the relative position between the first optical axis AX1r and the second optical axis AX2r.

One member and the other member may require adjustment even if the angle of the reflecting surface with respect to the incident surface is the same and the distance between the incident surface and the reflecting surface is the same.

As shown in FIG. 1, the optical path conversion element, the principal ray height of an off-axis light flux LB _Offax is low. Therefore, the two members can be downsized. When two miniaturized members are joined in parallel, the two optical axes must be brought close to each other.

However, in order to secure an appropriate parallax, the distance between the two optical axes needs to be widened to some extent. Therefore, the two members are integrated with the parallel plate in a separated state.

In this case, one of the members becomes rotatable about the first optical axis AX1f. Further, the other member is in a state of being rotatable around the second optical axis AX2f. Therefore, it becomes necessary to adjust the orientation of the first optical axis AX1r and the orientation of the second optical axis AX2r.

As described above, when the optical path conversion element is composed of two members, the necessity of adjustment at the time of assembly is significantly higher than when the optical path conversion element is composed of a single member. ..

If the adjustment at the time of assembly is insufficient, the formation position of the optical image and the orientation of the optical image will not match the position and orientation at the time of design. Such inconsistency can be corrected by image processing. However, in consideration of cost, the occurrence of such a mismatch is not preferable.

In order to prevent such inconsistency, a great amount of time must be spent on adjustment during assembly. However, if adjustment takes a long time at the time of assembly, work efficiency at the time of assembly will be significantly reduced.

For this reason, it is preferable that the optical path conversion element is composed of a single member. By configuring the optical path conversion element with a single member, it is possible to prevent a reduction in work efficiency during assembly. Further, correction by image processing is not necessary. Therefore, increase in cost can be suppressed.

In the image pickup apparatus for a stereoscopic endoscope of the present embodiment, the optical path changing element is composed of a first optical path changing element and a second optical path changing element, and the first optical path changing element and the second optical path changing element are different from each other. It is preferable that they are separately configured.

As described above, when the optical path conversion element is composed of two members, the necessity of adjustment at the time of assembly is significantly higher than when the optical path conversion element is composed of a single member. ..

However, when one member and the other member satisfy the following (I), (II), and (III), the optical path conversion element is configured by a single member by integrating the two members. It will be the same as if you did.
(I) The angle of the reflecting surface with respect to the incident surface is the same.
(II) The distance between the incident surface and the reflective surface is the same.
(III) The two members are large enough to be joined in parallel.

In this case, since the necessity for adjustment is reduced, the optical path conversion element can be configured by the first optical path conversion element and the second optical path conversion element.

A specific example of the optical system used in the image pickup apparatus for a stereoscopic endoscope of the present embodiment will be described. FIG. 11 is a cross-sectional view of an optical system used in the image pickup apparatus for a stereoscopic endoscope according to this embodiment.

An optical system for a stereoscopic endoscope includes, in order from the object side, a plano-concave negative lens L1, a positive meniscus lens L2 having a convex surface facing the image side, a negative meniscus lens L3 having a convex surface facing the image side, and a parallel plate. PL, an optical path conversion element PR, a plano-convex positive lens L4, a negative meniscus lens L5 having a convex surface facing the object side, and a biconvex positive lens L6.

The positive meniscus lens L2 and the negative meniscus lens L3 are cemented. The parallel plate PL and the optical path conversion element PR are joined. The negative meniscus lens L5 and the biconvex positive lens L6 are cemented together.

A cover glass C1 and a cover glass C2 are arranged on the image side of the biconvex positive lens L6. The cover glass C2 is a cover glass of the image sensor. The image pickup surface I of the image pickup element is located on the image side surface of the cover glass C2. Therefore, the optical image I is formed on the image side surface of the cover glass C2.

The optical path of the optical system is bent by the reflection surface of the optical path conversion element PR. In this example, a rectangular prism is used as the optical path changing element PR. The optical path after bending is orthogonal to the optical path before bending.

The numerical data of the above examples are shown below. In the surface data, r is the radius of curvature of each lens surface, d is the distance between the lens surfaces, nd is the d-line refractive index of each lens, and νd is the Abbe number of each lens.

In various data, f is the focal length of the entire system, Fr is the radius of the flare stop, and Ar is the radius of the brightness stop.

Numerical Example Unit mm

Surface data Surface number rd nd νd
1 ∞ 0.34 1.88815 40.76
2 0.51 0.27 1
3 (Aperture) ∞ 0.13 1
4 -2.484 0.45 1.62409 36.26
5 -0.639 0.3 1.75453 35.33
6 -0.84 0.317 1
7 (Aperture) ∞ 0.03 1
8 ∞ 0.3 1.93429 18.9
9 ∞ 0.0 1
10 (Aperture) ∞ 0.03 1
11 ∞ 0.70 1.93429 18.9
12 ∞ 0.03 1
13 (aperture) ∞ 0.2388 1
14 ∞ 0.5 1.48915 70.23
15 -1.566 0.1777 1
16 6.745 0.3 1.74706 27.79
17 1.072 0.8 1.48915 70.23
18 -1.686 1.2991 1
19 ∞ 0.7 1.51825 64.14
20 ∞ 0.02 1.5119 64.06
21 ∞ 0.7 1.6135 50.5
22 (imaging plane) ∞

Various data f 0.87
Fr (r3) 0.38
Fr (r7) 0.22
Fr (r13) 0.3
Ar (r10) 0.159

(Appendix)
The invention of the following configurations is derived from the above-mentioned embodiment.

(Appendix 1)
Further having an opaque plate,
The parallel plate is a colorless and transparent plate,
The imaging device for a stereoscopic endoscope, wherein the first opening and the second opening are holes formed in an opaque flat plate.
(Appendix 2)
The parallel plate is a colorless and transparent plate,
A light blocking portion, a first opening portion, and a second opening portion are formed on the object side surface of the parallel plate or the image side surface of the optical path conversion element,
The image pickup apparatus for a stereoscopic endoscope, wherein the light shielding portion is formed of a light shielding material.
(Appendix 3)
The parallel plate is made of an opaque material,
The imaging device for a stereoscopic endoscope, wherein the first opening and the second opening are holes formed in a parallel plate.
(Appendix 4)
A third opening located in the first optical path,
A fourth opening located in the second optical path,
The imaging device for a stereoscopic endoscope, wherein the third opening and the fourth opening are located closer to the image side than a predetermined position.
(Appendix 5)
The imaging device for a stereoscopic endoscope, wherein the third opening and the fourth opening are located on the image side surface of the optical path conversion element.
(Appendix 6)
Further having an opaque plate,
The parallel plate is a colorless and transparent plate,
The imaging device for a stereoscopic endoscope, wherein the third opening and the fourth opening are holes formed in an opaque flat plate.
(Appendix 7)
A light shielding portion, a third opening portion, and a fourth opening portion are formed on the image side surface of the optical path conversion element,
The image pickup apparatus for a stereoscopic endoscope, wherein the light shielding portion is formed of a light shielding material.
(Appendix 8)
The aperture of the aperture stop is a hole formed in an opaque flat plate,
The aperture stop is located between the parallel plate and the optical path changing element,
An image pickup apparatus for a stereoscopic endoscope, wherein a parallel plate, an aperture stop, and an optical path changing element are integrated.
(Appendix 9)
A light-shielding portion and an aperture of the aperture stop are formed on the image side surface of the parallel plate,
The image pickup device for a stereoscopic endoscope, wherein the light-shielding portion on the image side of the parallel plate is formed of a light-shielding material.
(Appendix 10)
A light blocking portion and an aperture portion of the aperture stop are formed on the object side surface of the optical path conversion element,
The image pickup apparatus for a stereoscopic endoscope, wherein the light-shielding portion on the object side surface of the optical path conversion element is formed of a light-shielding material.
(Appendix 11)
The imaging device for a stereoscopic endoscope, wherein the optical path changing element is composed of a single member.
(Appendix 12)
The optical path changing element comprises a first optical path changing element and a second optical path changing element,
The imaging device for a stereoscopic endoscope, wherein the first optical path changing element and the second optical path changing element are configured separately.

Although various embodiments of the present invention have been described above, the present invention is not limited to only these embodiments, and is configured by appropriately combining the configurations of these embodiments without departing from the spirit thereof. The form is also within the scope of the present invention.

INDUSTRIAL APPLICABILITY As described above, the present invention is a stereoscopic endoscope in which an optical system is configured by only two optical paths, and an objective optical system for a stereoscopic endoscope having an optical system with less stray light, a stereoscopic endoscope, and a stereoscopic system. It is suitable for imaging devices for endoscopes. Further, the present invention is suitable for a stereoscopic endoscope and an imaging device for a stereoscopic endoscope that are easy to manufacture.

OBJ1 1st optical system OBJ2 2nd optical system OP1 1st optical path OP2 2nd optical path L1-L6 lens PL parallel plate PR optical path conversion element C1, C2 cover glass IS image sensor I optical image (imaging surface)
I1 First optical image I2 Second optical image BAL _Lens frame P _in1 and P _in2 Point on inner surface of lens frame BAL
P1 position (predetermined position)
LB _flar Stray light LB _{ax On-} axis light flux LB _offax Off-axis light flux S Brightness stop ST1 First aperture ST2 Second aperture S _PLf Object side _{surface of} parallel plate PL S _PRr Image side surface 1, 20 of optical path conversion element PR 30 Light-shielding member 2, 31 Opaque flat plate 3, 21 1st opening part 4, 22 2nd opening part 10 Light-shielding area 11 Light-shielding part 12 1st opening part 13 2nd opening part 32 3rd opening part 33 Fourth aperture 40 Brightness diaphragm 41 Opaque flat plates 42, 43 Aperture AX1f First optical axis AX2f Second optical axis AX1r First optical axis AX2r Second optical axis

Claims (7)

A first optical system disposed in the first optical path and generating a first optical image;
A second optical system arranged in the second optical path to generate a second optical image;
An image pickup device for picking up the first optical image and the second optical image,
A parallel plate and an optical path conversion element are located in each of the first optical path and the second optical path,
The parallel plate and the optical path conversion element are integrated,
The parallel plate is composed of a single member,
The predetermined position is an arbitrary position between the object side surface of the parallel plate and the image side surface of the optical path conversion element,
In the first optical system and the second optical system, the chief ray height of the off- axis light flux is the lowest at the predetermined position,
The first opening is located in the first optical path,
The second opening is located in the second optical path,
The first opening and the second opening are both located closer to the object side than the predetermined position or closer to the image side than the predetermined position ,
Wherein the predetermined position, the stereoscopic endoscope imaging apparatus characterized that you have been disposed aperture stop. The imaging device for a stereoscopic endoscope according to claim 1, wherein the first opening and the second opening are located closer to the object side than the predetermined position. The imaging device for a stereoscopic endoscope according to claim 2, wherein the first opening and the second opening are located on an object side surface of the parallel plate. The imaging device for a stereoscopic endoscope according to claim 1, wherein the first opening and the second opening are located closer to the image side than the predetermined position. The imaging device for a stereoscopic endoscope according to claim 4, wherein the first opening and the second opening are located on an image side surface of the optical path conversion element. A first optical system disposed in the first optical path and generating a first optical image;
A second optical system arranged in the second optical path to generate a second optical image,
A parallel plate and an optical path conversion element are located in each of the first optical path and the second optical path,
The parallel plate and the optical path conversion element are integrated,
The parallel plate is composed of a single member,
The predetermined position is an arbitrary position between the object side surface of the parallel plate and the image side surface of the optical path conversion element,
In the first optical system and the second optical system, the chief ray height of the off-axis light flux is the lowest at the predetermined position,
The first opening is located in the first optical path,
The second opening is located in the second optical path,
The first opening and the second opening are both located closer to the object side than the predetermined position or closer to the image side than the predetermined position,
An objective optical system for a stereoscopic endoscope, wherein an aperture stop is arranged at the predetermined position. A stereoscopic endoscope comprising the objective optical system for a stereoscopic endoscope according to claim 6.

Images