JP2003005096A - Endoscopic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stereoscopic vision and measurement endoscope which makes a front end afocal adapter possible, is short in a rigid length, prevents dust from hindering observation and is free of the sense of discomfort in right and left images. SOLUTION: An objective optical system includes, successively from an object side toward an image side, a first unit 10, a second unit 20, a third unit 30 and an imaging unit. The first unit consists of negative lenses 101 and 103, the second unit consists of a first positive lens, the third unit consists of a second positive lens and the imaging unit consists of one imaging element 7. The first positive lens does not form the real image within the second unit the third unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope apparatus having an insertion portion with a small outer diameter including an objective optical system for measuring or stereoscopic vision.

[0002]

2. Description of the Related Art As applications of stereoscopic and measurement endoscopes, there are the following fields in industrial use.・ Inspection of cooling water supply pipes at nuclear power plants.・ Inspection of turbine blades of steam generators in power plants.・ Inspection of aircraft engine.

In the medical field, it has application to endoscopic surgery. In any case, it is possible to measure the size and depth of a wound, a crack, or an affected area without performing disassembly or abdominal laparotomy, and to perform repair or treatment safely and efficiently by using stereoscopic vision.

The conventional techniques of the stereoscopic endoscope and the measuring endoscope will be described with reference to FIGS. 8 to 13. Conventionally, when parallax is obtained for stereoscopic vision and measurement, it is widely known that two right and left identical optical systems are arranged in parallel. However, in reality, the left and right optical systems do not always have exactly the same images because there is always an error, and due to the relative difference between the left and right images, in the case of stereoscopic vision, the left and right images of the observer are fused. It may cause fatigue. Moreover, in the case of measurement, it causes a measurement error. Therefore, in order to suppress fatigue and errors, it is necessary to reduce the number of left and right optical components.

As means for solving this, there are the following two prior arts. Japanese Unexamined Patent Publication No. 8-122665 is shown in FIG. Japanese Patent Laid-Open No. 11-006967 is shown in FIG.

In these prior arts, the left and right optical systems are partly common to the left and right, and it can be expected to reduce errors. However, the aperture stop 55 is two apertures formed corresponding to the objective lenses arranged in parallel. Therefore, the deviation of the aperture position from the optical axis and the error of the left and right aperture shapes are
It is an error between the left and right images.

FIG. 8 shows a fourth embodiment of Japanese Patent Laid-Open No. 11-109257 as a prior art in which the aperture of the aperture stop is made one. The aperture stop 54 has one opening and solves the above-mentioned problems. This prior art is an advanced afocal adapter endoscope. An overall view of the distal afocal adapter endoscope is shown in FIG. 12 is an enlarged view of the tip portion. Further, FIG. 13 is a sectional view of the objective optical system at the tip. As shown in FIGS. 11 to 13, the distal afocal adapter 5 is detachable from the endoscope body 4.
As shown in FIG. 13, the master lens 6 includes the endoscope body 4
The focus position is adjusted to an object at infinity with respect to the image sensor 7.

The tip afocal adapter 5 is
It is possible to attach / detach at the position X on the object side of the master lens, by preparing different types of viewing angles and viewing directions suitable for the purpose of observation. FIG. 13A shows a state in which the tip afocal adapter 5 is attached. Figure 1 shows how it is removed
3 (b). The tip afocal adapter 5 is designed and designed so that when it is attached, it forms an image on the image pickup element so that the light rays emitted from each angle of view at the position X are approximately parallel rays (afocal) to the optical axis. To manufacture.

The tip afocal adapter type endoscope is
An expensive endoscope body can be commonly used for various observation purposes, which is economically advantageous. Further, since the attachment / detachment portion is afocal, the light flux diameter is large, and a real image is not formed, so that dust is less noticeable. Further, the influence of the focus shift due to the mounting position shift is small.

However, since a real image is formed on the final surface 9 of the objective lens, there are the following three problems. (1) Objective lenses 121 and 122 and relay lens 5
The total dimension of 0, 54, and 6 in the optical axis direction becomes long. This is a lens 12 with a positive focal length arranged in parallel at the tip.
Since the real images are formed at 1 and 122, the size of the objective lens directly increases the total length. At the tip of the insertion part,
It is not preferable because the portion that cannot be bent (hard length) becomes long. (2) If dust enters and adheres to the final surface 9 of the objective lens during manufacturing, it overlaps with the real image and is reflected in the image, which hinders stereoscopic vision and measurement, which is not preferable. (3) Since the real image is relayed and imaged on the image sensor, the image in the direction toward the central axis of the endoscope in the real image 9 is inverted by the image sensor 7 and imaged as an image in the direction outward. The left and right states of the image projected on the monitor are in a state in which the left and right states that are normally recognized by humans are replaced. That is, the image of the right eye becomes the image of the left eye on the monitor. Therefore, since the depth information is left-right reversed, the depth direction is reversed, and an inverse stereoscopic image is obtained, which is not preferable.

In summary of the above, the prior art has the following problems. In the prior art of, since the aperture stop 55 has two openings, there are left and right image errors. Moreover, the endoscope is neither a tip afocal nor an adapter type structure. The prior art of has a long rigid length,
The dust interferes with the observation and causes the problem of the inverse stereoscopic structure.

[0012]

DISCLOSURE OF THE INVENTION The present invention is capable of a tip afocal adapter, and at the same time, has a short hard length, does not hinder observation by dust, and does not cause reverse stereoscopic vision. The purpose is to provide an endoscope.

[0013]

SUMMARY OF THE INVENTION The present invention is an endoscope apparatus including an objective optical system for performing measurement or stereoscopic vision,
The objective optical system has a first first
A unit, a second unit, a third unit, and an imaging unit, wherein the first unit comprises a negative lens, the second unit comprises a first positive lens, and the third unit comprises a second positive lens, The image pickup unit includes one image pickup element, and the first positive lens does not form a real image in the second unit to the third unit.

Further, in the present invention, the condition that the second positive lens of the third unit can focus on an object at infinity and an object at about infinity is as follows. (1) is satisfied.

| Φa / φ | <0.1 (1) where φa is the combined power of the first unit and the second unit, and φ is the combined power of the first unit to the third unit Power.

Further, according to the present invention, there is provided a brightness diaphragm having one opening, and the brightness diaphragm is arranged at a position approximately at a rear focal point of the first positive lens of the second unit. And

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows the entire configuration of the endoscope objective optical system in the first embodiment.

The construction of this embodiment is such that, from the object side, a cover glass 51 for waterproofing and dustproofing, a first unit 10 in which two sets of lenses 101 and 102 having the same negative power are arranged in parallel, and a positive power. The second unit 20 of the lens, the third unit 30 of the lens of the positive power, and the image pickup unit including one image pickup device 7 as the image pickup means.

The angle of view of each of the two images is 60 °, and Fno.
It is 6.3. The negative lenses 101, 1 of the first unit 10
The configuration of No. 02 comprises, in order from the object side, a plano-concave lens 11 having a concave surface facing the image surface side and a meniscus concave lens 12 having a convex surface facing the image surface side, and a visual field mask 52 for determining a visual field range therebetween. is there. The visual field range and the visual field mask 52 have similar shapes. The visual field range has the shape and size as shown in FIG. 7 on the image sensor.

In the two sets of lenses 101 and 102, the distance between the straight lines (that is, the optical axes) passing through the centers of the radius of curvature of the respective surfaces is
It is 1.46 mm. In addition, two sets of lenses 101 and 10
In order to allow the two lenses to be arranged closer to each other in parallel, the inner side surfaces in contact with each other are cut off, and the lenses are machined so that the lens outer diameter shape becomes D-shaped when viewed from the optical axis direction.

The negative power (φ1) of the two sets of lenses 101 and 102 is -0.602 as a whole. The second unit 20 has, in order from the object side, a plano-convex lens 21 having a convex surface directed toward the image plane side, a cemented lens 22 having a concave and convex surface, and one aperture common to the two sets of lenses 101 and 102 of the first unit. The aperture stop 54 and the cover glass 25 form a part, and the aperture stop 54 and the cover glass 25 are in contact with each other.

The positive power (φ
2) is 0.232. The optical axis of the second unit (the straight line connecting the centers of the curvature radii of the respective surfaces) is decentered by 0.73 mm with respect to the optical axes of the two sets of lenses of the first unit. Further, the position of the aperture stop 54 is approximately the rear focus position of the entire second unit.

Further, a light shielding plate 53 is installed in contact with the plane of the plano-convex lens of the second unit. The light shielding plate 53 has an effect of cutting flare light generated at the edges and edges of the two sets of lenses of the first unit when strong reflected light comes in from the object side. The shape of the hole of the light shielding plate is similar to the visual field range of FIG. 7.

By the way, the combined power is as follows. Paraxial calculation is used for the calculation. Since the first unit is eccentric, the calculation is performed in a state where the first unit is slid in the direction perpendicular to the optical axis and the optical axes of the second unit and the third unit are aligned. The combined power φa (0.0263) of the first unit and the second unit is φa / φ = 0.02 with respect to the total power φ (1.03) of the first unit to the third unit.
It becomes 6.

Therefore, since it is smaller than 0.1, the outgoing light flux of each field angle in the second unit becomes approximately afocal. The third unit 30 includes a cover glass 35 and an uneven cemented lens 31 in order from the object side, and the whole has a positive power (φ3) of 0.389. The infrared cut filter 41 is arranged on the object side with respect to the image pickup device 7 to which the infrared cut filter 41 is joined. The optical axis of the third unit is collinear with the optical axis of the second unit. Seen from the image sensor,
Only the third unit is set so that it will focus on infinity.

The process of image formation in the optical system of the first embodiment will be described below. First, a light ray from an object is captured at a desired angle of view by the plano-concave lens 11 of the first unit negative lens. Next, by the action of the second concave meniscus lens 12, the chief ray of each field angle emitted from the first unit is made substantially parallel to the optical axis, and the exit pupil of the first unit is made to be approximately infinity. Further, the second unit can make the entrance pupil of the second unit approximately infinity by placing the brightness diaphragm 54 near the rear focus position.

From the above, the light beam transmitted through the first unit can be transmitted to the third unit without restriction by the brightness diaphragm having one common aperture. Since the light flux from the second unit is approximately an afocal light flux, it passes through the third unit whose focus is adjusted to approximately infinity and generates two images having a parallax with respect to one object on the image sensor. .

The third unit and the image pickup device are permanently installed in the main body of the endoscope apparatus, and the first unit is located at the position indicated by X in FIG.
The unit and the second unit can be attached and detached as the tip afocal adapter 5. The present embodiment is an endoscope in which the distal afocal adapter 5 is replaced for use. Since the attachment / detachment portion is an afocal light flux portion, dust on the attachment / detachment portion is inconspicuous, and it is possible to reduce the focus shift due to the looseness of the attachment / detachment mechanism.

In this embodiment, since the second unit and the third unit that form two images for stereoscopic vision are common components and the aperture of the aperture stop is also common, the error between the left and right images is reduced. It can be made smaller.

Further, in this embodiment, since the first unit is a negative lens, the first unit is a positive lens, and the first unit is different from the conventional system shown in FIG. 8 for forming a real image. Since it is short, the hard length can be shortened.

The meniscus concave lens 12 having a convex surface facing the image plane side in the first unit has a shape close to a concentric circle with the centers of curvature of the respective surfaces approaching each other. As a result, in the manufacturing process,
When it is difficult to suppress the eccentricity with respect to the outer diameter, a method of dividing into plano-concave lenses and plano-convex lenses to suppress the eccentricity and manufacturing them, and then joining them into one component may be considered.

The term "lens" used in the present invention does not refer to only a single lens, but also refers to a single lens, a combination of single lenses, a cemented lens, and a combination thereof.

Finally, FIG. 14 shows an example of the frame structure of the entire adapter equipped with this optical system. In the tip afocal adapter 5, the first unit 10 and the second unit 2
0, the third unit 30 is arranged at the tip of the endoscope apparatus body 4, and the adapter can be attached and detached at the X position by the screw of the knurl 8. <Lens Data of First Example> Angle of view: 60 ° Fno. : 6.3 ・ The third unit to the sixth face are the first unit, and the distance between the two sets of negative lenses is 1.46 mm. -The seventh surface to the fourteenth surface are decentered by 0.73 mm with respect to the two sets of negative lenses of the second unit and the first unit. -The 15th to 19th surface is the third unit.・ Φ1: −0.602 φ2: 0.232 φ3: 0.
389-φa: 0.0263 φ: 1.03 φa / φ:
0.026 ・ R: radius of curvature, d: surface spacing, n: refractive index, ν: Abbe number, INF: surface representing R nd ν object distance 11.5000 1 INF 0.4000 1.51633 64.1 2 INF 0.0500 3 INF 0.3000 1.88300 40.8 4 1.75546 0.5000 5 -1.27304 0.9500 1.88300 40.8 6 -2.23382 0.1530 7 INF 1.0000 1.77250 49.6 8 -4.59900 1.1132 9 12.48876 1.2000 1.72916 54.7 10 -2.22927 0.4000 1.80518 25.4 11 -12.78262 2.3216 (brightness diaphragm) INF 0.0300 13 INF 0.4000 1.51633 64.1 14 INF 0.1000 15 INF 0.4000 1.51633 64.1 16 INF 0.1000 17 2.36086 0.4000 1.84666 23.8 18 0.87942 1.0000 1.72916 54.7 19 -3.74638 0.6003 20 INF 1.6000 1.51400 75.0 21 INF 0.5000 1.49700 81.6 22 INF 0.0300 (imaging element surface) (second embodiment) Second The configuration of the endoscope objective optical system in the example is shown in FIG.

The difference between this embodiment and the first embodiment is that there is no cover glass at the tip and the lens construction of each of the first to third units. Therefore, the difference from the first embodiment will be described below.

The angle of view of each of the two images is 65 °, and Fno.
It is 6.4. The negative lenses 101, 1 of the first unit 10
The configuration of No. 02 includes, in order from the object side, a plano-concave lens 11 having a concave surface facing the image side, and a cemented lens 13 of a biconcave lens and a biconvex lens having negative power as a whole. A visual field mask 52 is sandwiched between them.

The distance between the optical axes of the negative lenses 101 and 102 in parallel is 1.46 mm, and the total power is (φ1) -0.64.
It is 1. The second unit 20 includes, in order from the object side, a biconvex lens 23, a cemented lens 24 having a negative power as a whole, and a cemented lens 2 having a positive power as a whole.
6 and two negative lenses 1 arranged in parallel in the first unit
The aperture stop 54 has a common aperture for 01 and 102, and the cover glass 25 in contact with the aperture stop.

Positive power (φ2) 0.234 as a whole
Is. The optical axis of the second unit is 0.73 with respect to the optical axes of the two sets of lenses 101 and 102 of the first unit.
mm eccentric. The combined power φa (0.0282) of the first and second units is φa / φ = 0.026 with respect to the total power φ (1.07) of the first to third units. The exit light flux at the corner becomes approximately afocal. The third unit 30 includes, in order from the object side, the cover glass 35 and the concave and convex cemented lens 31.
, And a biconvex lens 32, and the overall positive power (φ
3) 0.388.

The feature of the image formation of the second embodiment is that the negative lens of the first unit is a cemented lens having a negative power as a whole, so that the occurrence of chromatic aberration can be suppressed. . Further, since the second unit has the three-group configuration including the negative lens group, astigmatism and field curvature can be corrected well. Furthermore, since the third unit is made up of two groups, the aberration of the third unit alone is good. <Lens Data of Second Example> Angle of view: 65 ° Fno. 6.4: The first unit is the first unit from the first surface to the fifth surface, and the gap between the two negative lenses is 1.46 mm. The sixth to sixteenth surfaces are decentered by 0.73 mm with respect to the two sets of negative lenses of the second unit and the first unit. -The 17th to 23rd surface is the third unit. -Φ1: -0.641 φ2: 0.234 φ3: 0.
388 ・ φa: 0.0282 φ: 1.07 φa / φ:
0.026 ・ R: radius of curvature, d: surface spacing, n: refractive index, ν: Abbe number surface R d n ν object distance 10.3938 1 INF 0.3000 1.83481 42.7 2 1.92150 0.3529 3 -1.48425 0.3000 1.83481 42.7 4 4.85836 0.8000 1.69895 30.1 5 -2.70463 1.0204 6 16.94334 0.8000 1.88300 40.8 7 -24.31827 2.0375 8 2.23356 1.2000 1.77250 49.6 9 -10.41313 0.3000 1.59270 35.3 10 1.06742 0.7941 11 1.64417 0.8800 1.77250 49.6 12 -2.50406 0.3200 1.64769 33.8 13 1.76130 0.6180 (Aperture) INF 0.0163 15 INF 64.1 16 INF 0.1000 17 INF 0.4000 1.51633 64.1 18 INF 0.1000 19 3.87761 0.4000 1.84666 23.8 20 1.30626 1.1000 1.72000 50.2 21 -11.89684 0.6003 22 4.64203 1.0000 1.77250 49.6 23 -5.57008 0.1000 24 INF 1.6000 1.51400 75.0 25 INF 0.5000 1.49700 81.6 26 INF 0.0300 (Imaging Element Surface) (Third Embodiment) FIGS. 3 and 4 show the configuration of the optical system of the third embodiment.
Shown in. FIG. 4 is a side view of FIG.

The difference from the first embodiment is that a visual field direction changing prism 56 is provided instead of the cover glass, and the first unit is composed of one plano-concave lens with a concave surface facing the object side. That is, the third unit has the same configuration as that of the second embodiment.

Therefore, the structure and effect peculiar to the third embodiment will be described below. The first unit is composed of one plano-concave lens 14 each having a concave surface facing the object side. As a result, not only the number of parts is reduced and the cost is reduced, but also the assemblability is improved.

Further, in addition to the method of polishing and assembling two plano-concave lenses arranged in parallel one by one, it is advantageous for cost reduction to make two glass-molded lenses at a time by die pressing. is there.

Further, since the field mask 52 is installed on the plane side of the plano-concave lens 14 of the first unit, the light shielding plate 5 for cutting flare light described in the first and second embodiments.
Since it also has the function of 3, it is preferable because the structure is simple. <Lens Data of Third Example> Angle of view: 63 ° Fno. : 6.3-The first unit is from the fourth surface to the fifth surface, and the distance between the two sets of negative lenses is 1.46 mm. The sixth to thirteenth surfaces are decentered by 0.73 mm with respect to the two sets of negative lenses of the second unit and the first unit. -The 14th to 20th surface is the third unit. -Φ1: -0.495 φ2: 0.234 φ3: 0.
388 ・ φa: 0.0324 φ: 0.826 φa / φ:
0.039 ・ R: radius of curvature, d: surface spacing, n: refractive index, ν: Abbe number surface R dn ν object distance 8.5000 1 INF 2.2000 1.88300 40.8 2 INF 2.2000 1.88300 40.8 3 INF 0.4500 4 -1.78343 0.5000 1.88300 40.8 5 INF 2.0323 6 INF 1.0000 1.77250 49.6 7 -5.70060 0.1000 8 4.25418 1.2000 1.72916 54.7 9 -6.44107 0.4000 1.80518 25.4 10 9.34839 2.7488 (Aperture) INF 0.0300 12 INF 0.4000 1.51633 64.1 13 INF 0.1000 14 INF 0.4000 1.51633 64.1 15 INF 0.1000 16 3.87761 0.4000 1.84666 23.8 17 1.30626 1.1000 1.72000 50.2 18 -11.89684 0.6003 19 4.64203 1.0000 1.77250 49.6 20 -5.57008 0.1000 21 INF 1.6000 1.51400 75.0 22 INF 0.5000 1.49700 81.6 23 INF 0.0300 (Image sensor surface) (Fourth embodiment) Within the fourth embodiment The overall configuration of the endoscope objective optical system is shown in FIG.

The structure of the present embodiment has a first unit 10 in which two sets of lenses 101 and 102 having the same negative power are arranged in parallel in order from the object side, and a second unit 20 of a lens having a positive power. A brightness diaphragm 55 having two openings,
It is composed of a third unit 30 of a lens having a positive power and the image pickup device 7.

The construction of the negative lens of the first unit 10 consists of one plano-concave lens with the concave surface facing the image side, and the field mask 52 is provided immediately after that. The optical axis interval of the parallel negative lenses is 1.46 mm. Power (φ1) is -0.61
It is 0. The field mask also serves as the light shielding plate 53 that cuts flare light in the first embodiment.

The second unit comprises, in order from the object side, a biconvex lens 27, a biconvex lens 28, a biconcave lens 29a, and
A brightness diaphragm plate 55 having a waterproof and dustproof cover glass 25 and having two openings is provided in contact with the object side plane of the cover glass. It has a positive power (φ2) of 0.241 as a whole. The optical axis of the second unit is
The two negative lenses 101 and 102 of the first unit are decentered by 0.73 mm with respect to the optical axes. The combined power φa (0.0321) of the first and second units is the first
Since φa / φ = 0.030 with respect to the power φ (1.06) of the entire unit to the third unit, the exit light flux of each angle of view in the second unit is approximately afocal. The third unit includes, in order from the object side, the cover glass 35 and the concave and convex cemented lens 31.
Composed of. Total positive power (φ3) 0.400
Is.

The construction of the second unit is two biconvex lenses having positive power and one biconcave lens having negative power from the object side. Can be made closer to the optical axis, and the height of the aperture stop can be set to the position of this embodiment. As a result, the outer diameter of the third unit can be reduced, and an image can be formed without the light beam being eclipsed when the adapter is attached. The total length can be further shortened by configuring the optical parts of the tip adapter part with a small number of 5 points. <Lens Data of Fourth Example> Angle of view: 62 ° Fno. : 6.8-The first unit is the first unit from the first surface to the second surface, and the distance between the two negative lenses is 1.46 mm. -The third to eleventh surfaces are decentered by 0.73 mm with respect to the two sets of negative lenses of the second unit and the first unit. -The 12th to 16th surfaces are the third unit. -The aperture aperture is eccentric by 0.32 mm with respect to the optical axis of the second unit.・ Φ1: −0.610 φ2: 0.241 φ3: 0.
400 ・ φa: 0.0321 φ: 1.06 φa / φ:
0.030 ・ R: radius of curvature, d: surface spacing, n: refractive index, ν: Abbe number surface R dn ν object distance 11.7000 1 INF 0.3000 1.83481 42.7 2 1.36754 4.4836 3 4.00526 0.8000 1.72916 54.7 4 -14.46178 0.0500 5 2.78222 0.8000 1.77250 49.6 6 -20.03219 0.1000 7 -5.18445 0.6000 1.64769 33.8 8 1.68565 0.1500 (Aperture) INF 0.0300 10 INF 0.3000 1.51633 64.1 11 INF 0.1000 12 INF 0.3000 1.51633 64.1 13 INF 0.1000 14 2.32417 0.3000 1.84666 23.8 15 0.95341 0.8000 1.72916 54.7 16 -3.97083 0.5920 17 INF 1.6000 1.51400 75.0 18 INF 0.5000 1.49700 81.6 19 INF 0.0700 (imaging element surface) (Fifth Embodiment) FIG. 6 shows the overall configuration of the endoscope objective optical system in the fifth embodiment.

The lens configurations of the second unit 20 and the third unit 30 are different from those in the fourth embodiment. Also, the aperture stop 55
The configuration in which is arranged on the most object side of the second unit is different from the first to fourth embodiments.

Therefore, the structure and effect peculiar to the fifth embodiment will be described below. The second unit 20 is, in order from the object side,
An aperture stop 55 having two openings and a biconvex lens 2
7. A cemented lens 29b of a convex lens having a convex surface on the object side and a concave lens having a concave surface on the image side, and a cover glass 25.

Since the aperture stop 55 has two openings, it is not necessary to provide it at the rear focal position of the second unit.
Therefore, it may be put forward. By arranging the aperture stop 55 on the most object side of the second unit 20, the ray height of the first unit is lowered, and the lens outer diameter of the first unit can be reduced.

By having the cemented lens in the second unit, with the tip afocal adapter 5 attached, compared to the fourth embodiment, with respect to the eccentricity error of each lens that occurs during manufacturing, The influence is small and the assemblability can be improved.

The combined power φa of the adapter 5 composed of the first unit 10 and the second unit 20 becomes φa / φ = 0.018 with respect to the total power φ of the first unit to the third unit, The adapter has an afocal configuration.

The third unit comprises a cover glass 35, a negative and positive cemented lens 31, and a biconvex lens 32. Third
By forming the unit into two groups, the imaging performance of the master lens can be improved and the performance when the adapter is attached can be improved.

<Lens Data of Fifth Embodiment> Angle of view: 61 ° Fno. : 6.6-The first unit is the first unit from the first surface to the second surface, and the distance between the two negative lenses is 1.46 mm. -The third to tenth surfaces are decentered by 0.73 mm with respect to the two sets of negative lenses of the second unit and the first unit. -The 11th to 17th surface is the third unit. The apertures of the aperture stop are decentered by 0.73 mm with respect to the optical axis of the second unit.・ Φ1: −0.610 φ2: 0.231 φ3: 0.
388-φa: 0.0186 φ: 1.04 φa / φ:
0.018 ・ R: radius of curvature, d: surface spacing, n: refractive index, ν: Abbe number surface R d n ν object distance 11.7000 1 INF 0.3000 1.83481 42.7 2 1.36754 4.1111 (aperture) INF 0.0000 4 14.47189 0.8000 1.72916 54.7 5 -5.45097 0.0500 6 3.13076 1.3000 1.77250 49.6 7 9.87579 0.5500 1.64769 33.8 8 1.88234 0.1549 9 INF 0.4000 1.51633 64.1 10 INF 0.1000 11 INF 0.4000 1.51633 64.1 12 INF 0.1000 13 3.87761 0.4000 1.84666 23.8 14 1.30626 1.1000 1.72000 50.2 15 -11.89684 0.60000 16 4.63 420 49.6 17 -5.57008 0.1000 18 INF 1.6000 1.51400 75.0 19 INF 0.5000 1.49700 81.6 20 INF 0.0300 21INF (Imaging element surface) Currently, the size of the effective imaging range of the imaging element is approximately 2 vertical.
Although a product having a width of about 2.5 mm and a width of about 2.5 mm is manufactured, in the near future, the size will be reduced to half or less with the same number of pixels in the vertical and horizontal directions.
A size of 2.5 mm or less is assumed.

As described above, the endoscope apparatus according to the present invention has the following features. (1) An endoscope apparatus including an objective optical system for performing measurement or stereoscopic vision, wherein the objective optical system sequentially goes from an object side toward an image side, and includes a first unit, a second unit, and a third unit. A first lens unit, a second lens unit, a third lens unit, and an image pickup unit, the first unit includes a negative lens, the second unit includes a first positive lens, the third unit includes a second positive lens, and the image pickup unit includes one image pickup device. The endoscope device, wherein the first positive lens does not form a real image in the second unit to the third unit. (2) The second positive lens of the third unit can focus on an object at approximately infinity, and the following conditions (1) can be used to focus on an object at approximately infinity.
The endoscope apparatus according to item (1), which satisfies the formula.

| Φa / φ | <0.1 (1) where φa is a combined power of the first unit and the second unit, and φ is a combination of the first unit to the third unit Power. (3) An aperture stop having one aperture is provided, and the aperture stop is arranged at an approximately rear focus position of the first positive lens of the second unit (2).
The endoscope apparatus according to the item. (4) The negative lens of the first unit is a pair of negative lenses, the pair of negative lenses are arranged close to each other in parallel, and the optical axis of the first positive lens of the second unit is: The negative lens is eccentrically arranged with respect to the optical axis of at least one of the pair of negative lenses (3).
The endoscope apparatus according to the item. (5) The endoscope apparatus according to item (4), wherein the pair of negative lenses includes a lens having a concave surface facing the object side. (6) Each of the pair of negative lenses includes a first concave lens and a second concave lens, and the first concave lens is a single lens or a cemented lens with a final surface on the image side facing the concave surface toward the image side. The endoscope device according to item (4), wherein the second concave lens is a single lens or a cemented lens whose final surface on the image side is convex on the image side. (7) The pair of negative lenses have cutout portions on their respective side surfaces, and the pair of negative lenses are in contact with each other at the cutout portions so that the distances between the outer diameter centers of the pair of negative lenses are different from each other. The endoscope device according to item (4), which is smaller than the sum of the radii. (8) The endoscope apparatus according to the item (2), which has a brightness diaphragm having two openings, and the brightness diaphragm is arranged either before or after the second unit. (9) The negative lens of the first unit is a pair of negative lenses, the pair of negative lenses are arranged in close proximity to each other, and the optical axis of the first positive lens of the second unit is The endoscope apparatus according to item (8), wherein the endoscope device is arranged eccentrically with respect to the optical axis of at least one negative lens of the pair of negative lenses. (10) The pair of negative lenses each have a cutout portion on each side surface, and the pair of negative lenses are in contact with each other at the cutout portions so that the distances between the outer diameter centers of the pair of negative lenses are different from each other. The endoscope device according to the item (9), which is smaller than the sum of the radii of (11) The first positive lens of the second unit is the first
The first lens has a positive power and the surface closest to the object side is convex toward the object side, and the second lens has a negative power and the surface closest to the image side is negative. The endoscope apparatus according to item (9), which is concave on the image side. (12) The endoscope apparatus according to item (1), wherein a cover glass is provided on the object side of the first unit. (13) The endoscope apparatus according to item (1), wherein a visual field direction conversion prism is provided on the object side of the first unit. (14) The endoscope apparatus according to item (1), wherein a visual field mask is provided on the first unit, and the visual field mask corresponds to the negative lens of the first unit. (15) The endoscope apparatus according to item (1), wherein a flare stop is provided in the second unit. (16) The endoscope apparatus according to item (1), wherein the set of the first unit and the second unit is an adapter and is attachable to and detachable from the third unit. (17) An aperture stop is arranged integrally with a cover glass provided on the image side of the adapter (1
The endoscope apparatus according to the item 6). (18) The endoscope apparatus according to item (16), wherein a cover glass is provided on the object side of the third unit. (19) The endoscope apparatus according to any one of items (1) to (18), wherein the size of the effective image pickup range of the one image pickup device is 2 mm × 2.5 mm or less.

[0056]

According to the present invention, a distal afocal adapter is possible, and at the same time, the rigid length is short, dust does not interfere with observation, and stereoscopic and measurement endoscopes without discomfort in the left and right images. Can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical system according to a first example.

FIG. 2 is a sectional view of an optical system according to a second example.

FIG. 3 is a sectional view of an optical system according to a third embodiment.

FIG. 4 is a side sectional view of an optical system according to a third embodiment.

FIG. 5 is a sectional view of an optical system according to a fourth example.

FIG. 6 is a sectional view of an optical system according to a fifth embodiment.

FIG. 7 is a diagram showing a visual field range on an image sensor in each example.

FIG. 8 is a sectional view of an optical system of a conventional example (JP-A-11-109257).

FIG. 9 is a sectional view of an optical system of a conventional example (JP-A-8-122665).

FIG. 10 is a sectional view of an optical system of a conventional example (JP-A-11-006967).

FIG. 11 is an external view of a distal afocal adapter type endoscope apparatus.

FIG. 12 is a diagram showing a distal end portion of a distal afocal adapter type endoscope apparatus.

FIG. 13 is a cross-sectional view of an optical system of a distal afocal adapter type endoscope device.

FIG. 14 is a cross-sectional view showing an example of the frame configuration of the entire adapter in which the optical system of the first embodiment is mounted.

[Explanation of symbols]

4 Endoscope body 5 adapter 7 Image sensor 8 knurled 10 First unit 11,14 Plano-concave lens 12 Meniscus concave lens 13, 22, 24, 26, 29b, 31 cemented lens 20 Second Unit 21 Plano-convex lens 23, 27, 28, 32 biconvex lens 25, 35, 51 cover glass 29a biconcave lens 30 Third Unit 41 infrared cut filter 52 Field mask 53 Light shield 54, 55 Brightness diaphragm 56 View direction conversion prism 101, 102 negative lens

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI theme code (reference) G02B 23/24 G02B 23/24 B C G03B 35/10 G03B 35/10 F term (reference) 2H040 AA00 AA01 BA15 CA23 CA24 DA13 DA52 GA03 2H059 AA08 2H087 KA10 NA00 PA05 PA07 PA16 PA19 PB07 PB11 QA03 QA07 QA18 QA21 QA22 QA25 QA34 QA41 QA42 QA46 RA32 RA37 RA42 RA43 RA44 4C061 BB06 CC06 FF40 LL02H47H

Claims (3)

[Claims] 1. An endoscope apparatus including an objective optical system for performing measurement or stereoscopic vision, the objective optical system including a first unit and a second unit in order from an object side toward an image side. A third unit and an imaging unit are included, the first unit includes a negative lens, the second unit includes a first positive lens, the third unit includes a second positive lens, and the imaging unit includes one. An endoscope apparatus comprising an image pickup device, wherein the first positive lens does not form a real image in the second unit to the third unit. 2. The second positive lens of the third unit is capable of focusing on an infinitely distant object, and the following condition (1) is provided as a condition for focusing on an infinitely distant object. The endoscopic device according to claim 1, wherein the formula is satisfied. | Φa / φ | <0.1 (1) where φa is the combined power of the first unit and the second unit, and φ is the combined power of the first unit to the third unit . 3. An aperture stop having one aperture, wherein the aperture stop is arranged at a position approximately at a rear focal point of the first positive lens of the second unit. The endoscope apparatus according to 2.