WO2018225613A1

WO2018225613A1 - Imaging optical system and endoscope

Info

Publication number: WO2018225613A1
Application number: PCT/JP2018/020919
Authority: WO
Inventors: 菅武志
Original assignee: オリンパス株式会社
Priority date: 2017-06-07
Filing date: 2018-05-31
Publication date: 2018-12-13
Also published as: JP6501995B1; JPWO2018225613A1

Abstract

Provided are an imaging optical system that is for endoscope applications for steropsis and achieves both increased pixels and reduced flare, and an endoscope that has channels and achieves reduced flare. The imaging optical system is characterized by having two parallel optical systems OBJ-R, OBJ-L for imaging, and in that the flare aperture constitutions of the two optical systems OBJ-R, OBJ-L for imaging are different. In addition, the present invention is characterized by having the two optical systems OBJ-R, OBJ-L for imaging used for imaging for stereo viewing and a channel CH through which a treatment tool passes, and in that the gap between the optical axes Ax1, Ax2 for the two optical systems for imaging is 2 mm or less and the angle formed by a line joining the center of a line segment joining the centers of the lenses on the object side of the two optical systems for imaging and the centers of the channels and the line segment is within ±45°.

Description

Imaging optical system and endoscope

The present invention relates to an imaging optical system and an endoscope.

Conventionally, a stereoscopic observation system is known. The stereoscopic observation system uses a method in which two images with different parallax are imaged on an imaging surface of an imaging element on substantially the same plane for stereoscopic viewing. And in the structure of a prior art, in order to obtain two images from which parallax differs, it has two different optical systems (for example, refer patent document 1, 2).

JP 2014-046075 A JP 2006-288821 A

In the configuration of the prior art, flare may occur in the area between the two imaging optical systems. Such flare is undesirable because it degrades the quality of the observed image.

The present invention has been made in view of the above, and is an endoscope application for stereoscopic vision, and has an imaging optical system and a channel that achieve both high pixel count and flare reduction, and has reduced flare. An object is to provide an endoscope.

In order to solve the above-described problems and achieve the object, the present invention has two imaging optical systems arranged in parallel, and the configuration of the flare stop of the two imaging optical systems is different. It is an imaging optical system.

According to another aspect of the present invention, two imaging optical systems are arranged in parallel, and the diameter of the lens closest to the image side of one of the two imaging optical systems is the other optical system. An imaging optical system having a diameter larger than that of the lens closest to the image side of the system.

The present invention according to still another aspect includes two imaging optical systems used for imaging for stereoscopic observation and a channel through which a treatment tool is inserted, and the optical axes of the two imaging optical systems. Is 2 mm or less, and the angle between the line segment connecting the center of the line segment connecting the centers of the most object side lenses of the two imaging optical systems and the center of the channel, and the line segment is ± An endoscope characterized by being within 45 degrees.

The present invention is an endoscope application for stereoscopic vision, can provide an imaging optical system that achieves both high pixel count and flare reduction, and provides an endoscope having a channel and reduced flare. There is an effect that can be.

It is a figure which shows the lens cross-sectional structure of the imaging optical system which concerns on 1st Embodiment. It is a figure which shows the lens cross-sectional structure of the imaging optical system which concerns on 2nd Embodiment. (A) is a figure which shows the lens cross-sectional structure of the imaging optical system which concerns on 3rd Embodiment. (B) is a figure which shows the front structure of the one part lens of the imaging optical system which concerns on 3rd Embodiment. (A) is a figure which shows the front-end | tip structure seen from the front end side of the endoscope which concerns on 4th Embodiment. (B) is a figure which shows the whole endoscope apparatus. It is a figure which shows the lens cross-sectional structure of the optical system for imaging which concerns on each embodiment. It is a figure which shows the flare which generate | occur | produces in the conventional imaging optical system.

Hereinafter, a detailed description will be given based on the drawings according to the embodiment. In addition, this invention is not limited by this embodiment.

(First embodiment)
FIG. 1 is a diagram illustrating a lens cross-sectional configuration of the imaging optical system 100 according to the first embodiment. This embodiment has two imaging optical systems OBJ-R and OBJ-L arranged in parallel, and the configuration of the flare stop of the two imaging optical systems OBJ-R and OBJ-L is different. To do. For example, the optical system OBJ-R is an imaging optical system for the right eye. The optical system OBJ-L is an imaging optical system for the left eye.

The present embodiment and all of the second and third embodiments described below are imaging optical systems used for endoscope imaging for stereoscopic observation, and the lens L1 closest to the object side has two concave surface portions. This is one optical member having L11 and L12.

The optical system for stereoscopic observation is an optical system OBJ-R and an optical system OBJ-L that generate two optical images having parallax with each other. For example, the optical system OBJ-R forms an image for the right eye, and the optical system OBJ-L forms an image for the left eye. The distance between the two optical axes Ax1 and Ax2 is 2 mm or less.

Also, according to a preferred aspect of the present embodiment, first, the two imaging optical systems OBJ-R and OBJ-L have the same configuration of the flare stop FS. Further, the flare stop FS3 is disposed only on the image side of the lens L5 closest to the image side of one optical system OBJ-L.

Here, generation of flare in the conventional imaging optical system will be described. FIG. 6 is a diagram showing flare generated in a conventional imaging optical system. In the optical system OBJ-R for the right eye and the optical system OBJ-L for the left eye, light rays RAY-R and RAY-L indicated by solid lines from an object (not shown) are incident on the imaging surface I to form an image. Form.
Here, for example, in the optical system OBJ-L for the left eye, the light ray RAYf indicated by the broken line is reflected by the side surface of the lens L5 and causes flare. In particular, when image quality is improved by using a large number of pixels by increasing the number of pixels in the image sensor, it is necessary to form an optical image in a wider range of the image sensor surface, and the image light rays RAY-L, RAY The position on the image plane of −R becomes high. Along with this, the height of the light beam at the lens L5 increases, so that the light is reflected on the side surface of the lens and becomes flare.

In contrast, in the present embodiment, as shown in FIG. 1, the flare stop FS3 is disposed only on the image side of the lens L5 closest to the image side of one optical system OBJ-L. Thereby, flare generated by reflection on the side surface of the lens L5 can be reduced. Therefore, the quality of the observation image can be improved.

(Second Embodiment)
FIG. 2 is a diagram illustrating a lens cross-sectional configuration of the imaging optical system according to the second embodiment. In the imaging optical system 200 according to the second embodiment, one optical system OBJ-R and the other optical system OBJ-L of the two optical systems OBJ-L and OBJ-R are the same in the optical system. Flare stops FS1 and FS2 are provided at the respective positions. The opening diameter (opening diameter) φ1 of the flare stop FS1 included in one optical system OBJ-L is preferably smaller than the opening diameter φ2 of the flare stop FS2 included in the other optical system OBJ-R.

The value of the opening diameter is shown below.
Flare stop FS1 opening diameter φ1 = 0.5 (mm)
Flare stop FS2 opening diameter φ2 = 0.7 (mm)

With such a configuration of the flare stop, a light beam having a high image height that is originally a flare is shielded by the flare stop FS1 having a smaller aperture diameter φ1. Thereby, generation | occurrence | production of flare can be reduced.

In this embodiment, the brightness of the image of the optical system having the smaller aperture diameter is reduced. For this reason, the brightness differs between the right eye image and the left eye image. Therefore, it is preferable to adjust the gain by electrically increasing the dark image. That is, if both the aperture diameters φ1 and φ2 are reduced, it is necessary to increase the electrical gain for both images, which causes a problem of increasing electrical noise. In this embodiment, this problem is avoided.

(Third embodiment)
FIG. 3A is a diagram illustrating a lens cross-sectional configuration of the imaging optical system 300 according to the third embodiment.

The present embodiment includes two imaging optical systems OBJ-R and OBJ-L in parallel, and one of the two imaging optical systems OBJ-R and OBJ-L. The diameter LL1 of the lens L5 closest to the image side is larger than the diameter LL2 of the lens L5 closest to the image side of the other optical system OBJ-L.

FIG. 3B is a diagram illustrating a front configuration of a part of lenses of the imaging optical system according to the third embodiment. The most image-side lens L5 of the two imaging optical systems OBJ-R and OBJ-L has a circularly symmetric shape with respect to the optical axes Ax1 and Ax2. The diameter of the lens L5 closest to the image side of the two imaging optical systems OBJ-R and OBJ-L is the distance LL from the optical axes Ax1 and Ax2 to the linear part D.

In the lens L5, the diameter LL1 is made larger than the diameter LL2. Thereby, even if the height of the light beam at the lens L5 increases due to the increase in the number of pixels, it is possible to reduce the reflection of the light beam on the side surface of the lens L5. As a result, flare can be reduced.

(Fourth embodiment)
FIG. 4A is a diagram illustrating a distal end configuration viewed from the distal end side of an endoscope 400 according to the fourth embodiment. The present embodiment includes two imaging optical systems OBJ-L and OBJ-R used for imaging for stereoscopic observation, a channel CH through which a treatment tool is inserted, and illumination optical systems IL1 and IL2. The distance between the optical axes Ax1 and Ax2 of the two imaging optical systems OBJ-L and OBJ-R is 2 mm or less, and the center of the lens closest to the object of the two imaging optical systems OBJ-R and OBJ-L An angle α formed by a straight line connecting the center C1 of the line segment connecting the lines and the center C2 of the channel CH and the line segment is within ± 45 degrees.
(Endoscope explanation)
FIG. 4B is a diagram illustrating a schematic configuration of the endoscope apparatus 10 having the imaging optical system according to the embodiment. The endoscope apparatus 10 includes an endoscope 400 and an in vitro apparatus 7. The endoscope 400 includes an insertion unit 3, an operation unit 2, a connection cord unit 5, and a connector unit 6. The extracorporeal device 7 includes a power supply device, a video processor (not shown) that processes a video signal from the endoscope 400, and a display unit 8 that monitors and displays the video signal from the video processor.
The insertion portion 3 is an elongated and flexible member that can be inserted into a body cavity of a patient, and the distal end portion is a rigid distal rigid portion 1. A user (not shown) can perform various operations using an angle knob or the like provided in the operation unit 2.
Further, a connection cord portion 5 is extended from the operation portion 2. The connection cord portion 5 is connected to the in vitro device 7 via the connector 6.
The connection cord unit 5 communicates a power supply voltage signal from a power supply device or a video processor, a drive signal from an image sensor, and the like to an imaging system (not shown) built in the distal end rigid unit 1 and from the imaging system. The video signal is communicated to the video processor. Note that the video processor in the in-vitro device 7 can be connected to peripheral devices (not shown) such as a video printer and a recording device. The video processor can perform predetermined signal processing on the video signal from the imaging system and display an endoscopic image on the display screen (monitor) of the display unit 8.
Further, the endoscope 400 according to the present embodiment is not limited to the configuration in which the insertion portion 3 has flexibility. For example, a rigid endoscope in which the insertion portion 3 is not bent may be used.

In the upper gastrointestinal endoscope, it is common to insert and remove the treatment tool through the channel CH from a position obliquely below the screen side. This is in consideration of the operability of the treatment tool and the reduction of the endoscope diameter. As shown in FIGS. 4A and 6, when a bright spot exists in the parallax direction y, flare occurs only in the optical system closer to the bright spot.

A bright spot is generated when the treatment tool is irradiated with illumination light from the illumination optical systems IL1 and IL2. In other words, the treatment tool is made of a metal such as silver, and has a very high light reflectance as compared to the digestive tract tissue. For this reason, when a treatment tool such as a forceps is inserted and removed from the channel CH, the reflected light from the forceps becomes a strong luminescent spot. Therefore, a horizontal streaky flare occurs only in the left-eye imaging close to the forceps.

Also, according to a preferred aspect of the present embodiment, of the two imaging optical systems OBJ-R and OBJ-L, the imaging optical system OBJ-L close to the channel CH has a flare prevention unit. Preferably it is.

Here, the flare prevention unit is a configuration for reducing flare described in the first embodiment, the second embodiment, and the third embodiment.

Thereby, in the endoscope having the above-described imaging optical system, there is an effect that flare caused by a bright spot in the treatment instrument or the like can be reduced. In addition, each of the above-described embodiments has an effect that the parallax is short, the pixel size is increased, and flare can be reduced. That is, when the parallax is shortened, it is necessary to reduce the diameter (LL1 and LL2 in FIG. 3) of the lens L5 closest to the image side. However, when the lens diameter is reduced, as shown in FIG. 6, light is reflected from the side surface of the lens L5 and flare occurs. In this embodiment, attention is paid to the fact that bright spots (strong light) that cause flare are generated by the reflection of the treatment tool, and the channel for inserting / removing the treatment tool and the flare prevention unit are provided only in a specific optical system. By arranging, the above-mentioned operational effects are realized.

Hereinafter, each example will be described. FIG. 5 is a diagram showing a lens cross-sectional configuration of the imaging optical system according to each of the embodiments.

(Numerical example of optical system for imaging)
The lens data of the two imaging optical systems OBJ-R and OBJ-L in the first to fourth embodiments are the same. For this reason, data of one of the two imaging optical systems OBJ-R and OBJ-L is shown as a representative example below.

The imaging optical system includes, in order from the object side, a plano-concave first lens L1 having a negative refractive power with a concave surface facing the image side and a meniscus-shaped first lens having a negative refractive power with a concave surface facing the object side. Two lenses L2, a plano-convex third lens L3 having a positive refractive power with the plane facing the image side, a filter F1 that is a parallel plate, an aperture stop S, and a positive refraction with the plane facing the object side A fourth lens L4 having a planoconvex shape having power, a fifth lens L5 which is a cemented lens having a positive refractive power in which a biconvex positive lens and a negative meniscus lens having a convex surface facing the image side are cemented, and a cover glass F2 and a CCD cover glass CG.

Also, the YAG laser cut coating is applied to the object side of the infrared absorption filter F1, and the LD laser cut coating is applied to the image side. Further, the cover glass F2 and the CCD cover glass CG are joined. d16 is an adhesive layer.

The numerical data of each of the above examples is shown below. Symbols r are the radii of curvature of the lens surfaces, d is the spacing between the lens surfaces, ne is the refractive index of the e-line of each lens, νd is the Abbe number of each lens, and Fno is the F number. The diaphragm is a brightness diaphragm.

Numerical example 1
Unit mm

Surface data Surface number r d ne νd
1 ∞ 0.35 1.88815 40.76
2 0.592 0.564 1
3 -1.522 0.46 1.85504 23.78
4 -2.406 0.04 1
5 4.079 0.63 1.85504 23.78
6 ∞ 0.03 1
7 ∞ 0.4 1.49557 75.00
8 ∞ 0.38 1
9 (Aperture) ∞ 0.03 1
10 ∞ 0.42 1.75453 35.33
11 -1.717 0.437 1
12 1.381 0.82 1.69979 55.53
13 -0.907 0.36 1.93429 18.90
14 -4.334 0.38 1
15 ∞ 0.5 1.51825 64.14
16 ∞ 0.01 1.515 64.00
17 ∞ 0.35 1.507 63.26
Image plane ∞

Various data focal length 0.43
Maximum image height 0.429
Angle of View 163.4
Fno 3.77
Object distance 7.25

Note that the above-described imaging optical system may satisfy a plurality of configurations at the same time. This is preferable for obtaining a good imaging optical system and endoscope. Moreover, the combination of a preferable structure is arbitrary.
Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and may be implemented by appropriately combining the configurations of these embodiments without departing from the spirit of the present invention. The form is also within the scope of the present invention. For example, the optical system can be variously modified. The optical system may be a zoom optical system having a movable part. In this embodiment, the lens L1 is formed by one optical member, but the two optical systems may be formed by separate members. Further, the lenses L1 to L3 may be a common lens in the two optical systems. In that case, the distance between the optical axes of the lens L4 and the lens L5 may be set to 2 mm or less.

As described above, the present invention is an endoscope application for stereoscopic vision, and is useful for an endoscope that has an imaging optical system and a channel that achieve both high pixel count and flare reduction, and has reduced flare. .

100, 200, 300 Imaging optical system 400 Endoscope L1-L5 Lens Ax1, Ax2 Optical axis S Brightness diaphragm F1 Filter F2 Cover glass CG CCD cover glass L11, L12 Concave surface FS, FS1, FS2, FS3 Flare diaphragm OBJ- R, OBJ-L Optical system for imaging
IL1, IL2 Illumination optical system CH channel φ1, φ2 Aperture diameter LL1, LL2 Diameter

Claims

Having two imaging optical systems in parallel;
An imaging optical system, wherein the two imaging optical systems have different flare aperture configurations.
2. The imaging optical system according to claim 1, wherein a flare stop is disposed only on the image side of the lens closest to the image side of one of the optical systems.
The one optical system and the other optical system each have a flare stop at the same position in the optical system,
The imaging optical system according to claim 1, wherein an aperture diameter of the flare stop included in one of the optical systems is smaller than an aperture diameter of the flare stop included in the other optical system.
Having two imaging optical systems in parallel;
An imaging optical system, wherein a diameter of a lens closest to the image side of one of the two optical systems for imaging is larger than a diameter of a lens closest to the image side of the other optical system.
The most image-side lens of the two imaging optical systems has a linear portion obtained by linearly cutting a circular arc portion in the parallax direction among shapes that are circularly symmetric with respect to the optical axis,
The imaging optical system according to claim 4, wherein the diameter of the lens closest to the image side of the two imaging optical systems is a distance from an optical axis to the linear portion.
Two imaging optical systems used for imaging for stereoscopic observation;
A channel through which the treatment tool is inserted,
The distance between the optical axes of the two imaging optical systems is 2 mm or less,
The angle formed by the straight line connecting the center of the line segment connecting the centers of the most object side lenses of the two imaging optical systems and the center of the channel and the line segment is within ± 45 degrees. An endoscope characterized by that.
The endoscope according to claim 6, wherein, of the two imaging optical systems, the imaging optical system close to the channel includes a flare prevention unit.