WO2020054012A1 - Tip member, endoscope optical system, endoscope, and endoscope system - Google Patents

Abstract

Provided are a tip member, an endoscope optical system, an endoscope, and an endoscope system, whereby an object positioned near the outer circumferential surface of a tip optical system or an object in contact with the outer circumferential surface of a tip optical system can be clearly observed. The tip member is connected to a holding member. The tip member 2 has a tip optical system 4. The tip optical system 4 has an inner surface 4b and an outer circumferential surface 4a. An end of the outer circumferential surface 4a is positioned upon an optical axis of the tip optical system 4. The inner surface 4b is positioned further on the holding member 6 side than the position of an end of the outer circumferential surface 4a. The inner surface 4b has a first region in contact with an end surface of the holding member 6. The area between the inner surface 4b and the outer circumferential surface 4a is filled with a transparent substance having a refractive index greater than 1 and fulfills conditional formulas (1), (2).　1.3 < N < 1.6 (1) 0.4 < L/d < 1.5 (2)

Description

End member, endoscope optical system, endoscope, and endoscope system

The present invention relates to a tip member, an endoscope optical system, an endoscope, and an endoscope system.

光学 As an optical device for observing the side, for example, there is an endoscope. As the observation with the endoscope, for example, there is an observation inside a body cavity and an observation inside a thin pipe. Such observation is performed in a small space. Therefore, the endoscope is required to have a smaller diameter of the insertion portion.

観 察 When observing the inside of a body cavity or the inside of a pipe, there may be a case where a granular material or an opaque liquid (hereinafter, referred to as “opaque substance”) exists between the object and the imaging optical system. Examples of the powder include sand and colloid. An opaque liquid is, for example, blood.

In this case, the illumination light hardly reaches the object, so that the object cannot be illuminated with sufficient brightness. In addition, since the amount of light incident on the imaging optical system from the object is reduced, it becomes difficult to observe the object.

装置 Patent Documents 1 to 4 disclose devices in which a transparent cylindrical member (hereinafter, referred to as a “cylindrical member”) is disposed at the tip of the insertion portion. In the devices disclosed in Patent Literatures 1 and 3, a lens cover is disposed at a distal end of a medical device. In the device disclosed in Patent Literature 2, a transparent cap is disposed at the distal end of the endoscope. In the device disclosed in Patent Document 4, a tip is arranged at the tip of an endoscope.

In the devices disclosed in Patent Documents 1 and 3, an offset can be provided between the device and the tissue by the lens cover. In the device disclosed in Patent Document 2, an opaque liquid can be removed by bringing a transparent cap into contact with an object. In the device disclosed in Patent Document 4, an offset can be provided between the device and the tissue by the tip.

Japanese Unexamined Patent Publication No. 2010-522585 JP-A-64-80335 U.S. Pat. No. 8,414,480 U.S. Pat. No. 8,932,208

照明 A lighting unit and an imaging optical system are arranged at the distal end of the medical device and the distal end of the endoscope. When the tubular member is disposed at the distal end, the illumination light is reflected on the inner surface of the tubular member. When the reflected illumination light enters the imaging optical system, flare occurs due to the incident light. Therefore, it is difficult to clearly observe the image of the object.

で は In the lens cover disclosed in Patent Document 1, the inner surface is a part of a spherical surface or a part of an elliptical surface. In this case, the illumination light reflected on the inner surface is likely to enter the imaging optical system. Therefore, flare is likely to occur. As a result, it is difficult to perform clear observation.

キ ャ ッ プ In the cap disclosed in Patent Document 2, the inner surface is a cylindrical surface. The bottom surface of the cylinder is a plane, and the plane faces the observation optical system. In this case, the illumination light reflected on the bottom surface easily enters the imaging optical system. Therefore, flare is likely to occur. As a result, it is difficult to clearly observe the image of the object.

レ ン ズ In the lens cover disclosed in Patent Document 3 and the chip disclosed in Patent Document 4, reflection of illumination light on the inner surface is considered. However, the imaging optical system has not been optimized. Therefore, it is difficult to clearly observe the image of the object.

The present invention has been made in view of such a problem, and clearly observes an object located in the vicinity of the outer peripheral surface of the tip optical system and an object in contact with the outer peripheral surface of the tip optical system. It is an object of the present invention to provide a tip member, an endoscope optical system, an endoscope, and an endoscope system that are capable of being operated.

In order to solve the above-described problems and achieve the object, a tip member according to at least some embodiments of the present invention includes:
A tip member connected to the holding member,
The tip member has a tip optical system,
The tip optical system has an inner surface and an outer peripheral surface,
One end of the outer peripheral surface is located on the optical axis of the tip optical system,
The inner surface is located closer to the holding member than the position of one end of the outer peripheral surface,
The inner surface has a first region in contact with the end surface of the holding member,
The space between the inner surface and the outer surface is filled with a transparent substance having a refractive index greater than 1.
It is characterized by satisfying the following conditional expressions (1) and (2).
1.3 <N <1.6 (1)
0.4 <L / d <1.5 (2)
here,
N is the refractive index of the transparent material at d-line,
L is the distance from one end to the first intersection,
d is the distance from one end to the second intersection,
A first intersection is an intersection between a predetermined line and the optical axis,
The predetermined line is a straight line that is in contact with the other end of the outer peripheral surface and is orthogonal to the optical axis;
The second intersection is the intersection between the inner surface and the optical axis,
It is.

An endoscope optical system according to at least some embodiments of the present invention includes:
The tip member described above,
An imaging optical system arranged on the holding member.

An endoscope according to at least some embodiments of the present invention includes:
The endoscope optical system described above, an image sensor,
Lighting part,
An insertion portion having a holding member,
The imaging optical system and the illumination unit are disposed inside the holding member.

An endoscope system according to at least some embodiments of the present invention includes:
The endoscope described above,
An image processing device;
And a light source device.

According to the present invention, a tip member capable of clearly observing an object located in the vicinity of the outer peripheral surface of the tip optical system or an object in contact with the outer peripheral surface of the tip optical system, an endoscope optical system , An endoscope, and an endoscope system.

It is a figure showing the tip member of this embodiment. It is a figure showing the 1st example of an illumination part. It is a figure showing the 2nd example of a lighting part. It is a figure showing flare light. FIG. 6 is a diagram illustrating parameters used in a conditional expression. FIG. 6 is a diagram illustrating parameters used in a conditional expression. It is a figure showing the 1st example of an outer peripheral surface. It is a figure showing the 2nd example of an outer peripheral surface. It is a graph which shows the relationship between the magnitude of flare light, and the vertex angle of a cone. FIG. 6 is a diagram illustrating parameters used in a conditional expression. FIG. 6 is a diagram illustrating parameters used in a conditional expression. It is a figure showing the tip member of this embodiment. It is a figure showing the 1st example of a tip member. It is a figure showing the 2nd example of a tip member. It is a figure showing the 3rd example of a tip member. It is a figure showing the 4th example of a tip member. It is a figure showing the 5th example of a tip member. It is a figure showing the 6th example of a tip member. FIG. 4 is a diagram illustrating an image forming relationship of an optical system having a field curvature aberration. FIG. 3 is a diagram illustrating a virtual image when an object plane is a plane. FIG. 3 is a diagram illustrating a virtual image when an object surface is a curved surface. FIG. 2 is a diagram illustrating a cross-sectional view of an endoscope optical system according to the present embodiment. FIG. 3 is a lens cross-sectional view of the imaging optical system according to the first embodiment. FIG. 9 is a lens cross-sectional view of an imaging optical system according to a second embodiment. FIG. 13 is a lens cross-sectional view of an imaging optical system according to a third embodiment. FIG. 14 is a sectional view of a lens of an imaging optical system according to a fourth embodiment. FIG. 14 is a lens cross-sectional view of an imaging optical system according to a fifth embodiment. FIG. 13 is a lens cross-sectional view of an imaging optical system according to a sixth embodiment. FIG. 14 is a lens cross-sectional view of the imaging optical system of Example 7; FIG. 14 is a lens cross-sectional view of an imaging optical system according to an eighth embodiment. FIG. 3 is an aberration diagram of the image forming optical system according to the first embodiment. FIG. 10 is an aberration diagram of the image forming optical system according to the second embodiment. FIG. 13 is an aberration diagram of the imaging optical system of the third embodiment. FIG. 13 is an aberration diagram of the image forming optical system according to the fourth embodiment. FIG. 15 is an aberration diagram of the imaging optical system of the fifth embodiment. FIG. 14 is an aberration diagram of the imaging optical system of the sixth embodiment. FIG. 14 is an aberration diagram of the image forming optical system according to the seventh embodiment. FIG. 15 is an aberration diagram of the imaging optical system of the eighth embodiment. FIG. 2 is a cross-sectional view of the endoscope optical system according to the first embodiment. FIG. 9 is a cross-sectional view of the endoscope optical system according to the second embodiment. FIG. 10 is a cross-sectional view of an endoscope optical system according to a third embodiment. FIG. 14 is a sectional view of an endoscope optical system according to a fourth embodiment. FIG. 14 is a sectional view of an endoscope optical system according to a fifth embodiment. FIG. 14 is a sectional view of an endoscope optical system according to a sixth embodiment. FIG. 14 is a sectional view of an endoscope optical system according to a seventh embodiment. FIG. 14 is a sectional view of an endoscope optical system according to an eighth embodiment. FIG. 19 is a sectional view of an endoscope optical system according to a ninth embodiment. FIG. 21 is a sectional view of an endoscope optical system according to a tenth embodiment. FIG. 21 is a sectional view of an endoscope optical system according to an eleventh embodiment. FIG. 21 is a sectional view of an endoscope optical system according to a twelfth embodiment. It is a figure showing an insertion part of an endoscope of this embodiment. It is a figure showing an example of an endoscope of this embodiment, and an example of an endoscope system.

立 ち Before describing the examples, the operation and effect of the embodiment according to an aspect of the present invention will be described. In describing the operation and effect of the present embodiment specifically, a specific example will be described. However, as in the case of the embodiments described later, the illustrated embodiments are only a part of the embodiments included in the present invention, and there are many variations in the embodiments. Therefore, the present invention is not limited to the illustrated embodiment.

The distal end member of the present embodiment is a distal end member connected to a holding member, the distal end member has a distal end optical system, the distal end optical system has an inner surface and an outer peripheral surface, and an outer peripheral surface. Is located on the optical axis of the tip optical system, the inner surface is located closer to the holding member than the position of the one end of the outer peripheral surface, and the inner surface has a first region in contact with the end surface of the holding member. The gap between the outer peripheral surface and the outer peripheral surface is filled with a transparent substance having a refractive index larger than 1, and satisfies the following conditional expressions (1) and (2).
1.3 <N <1.6 (1)
0.4 <L / d <1.5 (2)
here,
N is the refractive index of the transparent material at d-line,
L is the distance from one end to the first intersection,
d is the distance from one end to the second intersection,
A first intersection is an intersection between a predetermined line and the optical axis,
The predetermined line is a straight line that is in contact with the other end of the outer peripheral surface and is orthogonal to the optical axis;
The second intersection is the intersection between the inner surface and the optical axis,
It is.

FIG. 1 is a diagram showing a tip member of the present embodiment. The tip member of the present embodiment can be used for an endoscope optical system. Therefore, description will be made using the endoscope optical system.

The endoscope optical system 1 has a tip member 2 and an imaging optical system 3. The tip member 2 is connected to the holding member 6. The imaging optical system 3 is disposed on the holding member 6. In FIG. 1, the tip member 2 and the holding member 6 are illustrated in a separated state for easy viewing.

The tip member 2 has a tip optical system 4. The shape of the tip optical system 4 can be a shape having an axis of symmetry. By doing so, the tip optical system 4 can be easily manufactured. Further, the imaging performance of the imaging optical system 3 can be improved with a small number of lenses. When the shape of the tip optical system 4 has a symmetry axis, the symmetry axis can be regarded as the optical axis of the tip optical system 4.

The tip optical system 4 has an outer peripheral surface 4a and an inner surface 4b. One end of the outer peripheral surface 4 a is located on the optical axis of the tip optical system 4. The inner surface 4b is positioned closer to the holding member 6 than one end of the outer peripheral surface 4a.

間隔 The distance between the outer peripheral surface 4a and the optical axis of the tip optical system 4 (hereinafter, referred to as “optical axis”) varies from one end to the other end. The range in which the interval changes may be a partial range between one end and the other end, or may be an entire range between one end and the other end. The outer peripheral surface 4a may include a shape in which the distance between the outer peripheral surface 4a and the optical axis gradually increases from one end to the other end (hereinafter, referred to as a “tapered shape”).

The inner surface 4b has a first region that is in contact with the end surface of the holding member 6. In FIG. 1, the end surface of the holding member 6 is a plane orthogonal to the optical axis. Therefore, the first region is formed by a plane orthogonal to the optical axis. Further, the parallel flat plate 5 is arranged in the same plane as the end surface of the holding member 6. Therefore, in FIG. 1, the entire inner surface 4b is a plane orthogonal to the optical axis.

In the tip optical system 4 shown in FIG. 1, the outer peripheral surface 4a has a conical surface and a cylindrical surface. However, the shape of the outer peripheral surface 4a is not limited to the shape shown in FIG. The inner surface 4b has a flat surface. However, the entire surface of the inner surface 4b may not be a flat surface.

で は In a conical surface, the distance between the surface and the central axis gradually increases from one end to the other end. Therefore, the conical surface can be regarded as a surface representing a tapered shape.

の 間 The space between the outer peripheral surface 4a and the inner surface 4b is filled with a transparent substance having a refractive index larger than 1.

As described above, in an environment where an opaque substance exists between the object and the imaging optical system, light incident on the imaging optical system from the object decreases. Therefore, it is difficult to clearly observe the object.

で も In order to clearly observe an object even in such an environment, it is necessary to reduce the number of opaque substances or eliminate the opaque substances. When the tip optical system 4 is used, the outer peripheral surface 4a may be located near the object, or the outer peripheral surface 4a may be brought into close contact with the object. In this manner, the number of opaque substances can be reduced or the opaque substances can be eliminated. As a result, the object can be clearly observed.

観 察 In observing an object using the endoscope optical system 1, the tip optical system 4 is moved closer to the object. When the tip optical system 4 contacts the object, the tip optical system 4 is further pushed. When the shape of the outer peripheral surface 4a is tapered, the distal end optical system 4 can be easily pushed toward the object.

(4) When the tip optical system 4 is pushed toward the object, the opaque substance is pushed away because the object approaches the tip optical system 4. That is, opaque substances are excluded. As a result, the outer peripheral surface 4a can be located near the object, or the outer peripheral surface 4a can be brought into close contact with the object.

物体 In order to observe an object, it is necessary to illuminate the object. The illumination of the object can be performed by the illumination unit. Hereinafter, an example of the lighting unit will be described. In the following example, the illumination unit is arranged at the insertion section of the endoscope. For example, a light guide or a light emitting diode (LED) is used for the lighting unit.

FIG. 2 is a diagram showing a first example of the lighting unit. The insertion section 10 has a holding member 11. The holding member 11 has an illumination unit 12 and a parallel flat plate 5. An imaging optical system (not shown) is arranged inside the holding member 11. The shape of the illumination unit 12 is a ring. The parallel plate 5 is located inside the illumination unit 12.

FIG. 3 is a diagram showing a second example of the illumination unit. The insertion section 20 has a holding member 11. The holding member 11 has an illumination unit 21 and the parallel flat plate 5. An imaging optical system (not shown) is arranged inside the holding member 11. The shape of the illumination unit 21 is a circle. The parallel flat plate 5 and the illumination unit 21 are arranged in parallel.

照明 Illumination light emitted from the illumination unit includes diffused light, convergent light, or diffused light and scattered light. By appropriately setting the size and position of the illumination, the entire field of view of the observation optical system (hereinafter, referred to as “field of view”) can be illuminated.

The illumination light passes through the inner surface 4b and enters the tip optical system 4. The illumination light incident on the tip optical system 4 exits from the outer peripheral surface 4a. Thereby, the object is illuminated.

Light reflected by the object (hereinafter, referred to as “imaging light”) passes through the outer peripheral surface 4 a and enters the tip optical system 4. The imaging light that has entered the tip optical system 4 exits from the inner surface 4b and enters the imaging optical system 3. Thereby, side view observation of the entire circumference can be performed. In addition, by pushing the tip optical system 4 against the object, it becomes possible to observe the object throughout the traveling direction.

先端 As shown in FIG. 1, the endoscope optical system 1 is provided with a distal end member 2. Therefore, the imaging light and the illumination light pass through the tip member 2. Here, the refractive index between the outer peripheral surface 4a and the inner surface 4b is larger than 1. Therefore, when the space between the outer peripheral surface 4a and the object is filled with air, the refractive index greatly changes from the outer peripheral surface 4a as a boundary.

フ レ Fresnel reflection occurs at the boundary where the refractive index changes. When the refractive index changes significantly, the light intensity of the light reflected by Fresnel reflection increases. Therefore, flare light is easily generated on the outer peripheral surface 4a.

FIG. 4 is a diagram showing flare light. FIG. 4A is a diagram illustrating a first example of flare light. FIG. 4B is a diagram illustrating a second example of the flare light. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

In the first example, the illumination light emitted from the illumination unit 12 passes through the inner surface 4b and enters the tip optical system 4. The illumination light incident on the tip optical system 4 reaches the outer peripheral surface 4a. Light transmission and light reflection occur on the outer peripheral surface 4a. The illumination light reflected on the outer peripheral surface 4a enters the outer peripheral surface 4a again. The incident position is a position different from the first reflected position.

(4) The illumination light incident on the outer peripheral surface 4a is reflected by the outer peripheral surface 4a. The illumination light reflected by the outer peripheral surface 4a further enters the outer peripheral surface 4a. The incident position is a position different from the first reflected position and the second reflected position. The illumination light incident on the outer peripheral surface 4a is reflected by the outer peripheral surface 4a.

の う ち Of the illumination light reflected three times by the outer peripheral surface 4a, a part of the illumination light is incident on the imaging optical system 3 as shown by a solid line. Thus, in the first example, flare light is generated by three reflections. As a result, flare occurs in the field of view.

In the second example, the illumination light emitted from the illumination unit 12 passes through the inner surface 4b and enters the tip optical system 4. The illumination light incident on the tip optical system 4 reaches the outer peripheral surface 4a. The illumination light reflected on the outer peripheral surface 4a enters the outer peripheral surface 4a again. The incident position is a position different from the first reflected position. The illumination light incident on the outer peripheral surface 4a is reflected by the outer peripheral surface 4a.

(4) Of the illumination light reflected twice by the outer peripheral surface 4a, a part of the illumination light enters the imaging optical system 3 as shown by a solid line. Thus, in the second example, flare light is generated by two reflections. As a result, flare occurs in the field of view.

光 The magnitude of the reflected light intensity is determined by the Fresnel reflectivity. Fresnel reflectivity depends on the refractive index difference and the angle. As the refractive index difference increases, the light intensity of the light reflected by Fresnel reflection increases.

外 周 As described above, the outer peripheral surface is located near the object, or the outer peripheral surface is in close contact with the object. Therefore, in order to suppress generation of flare light, it is important to appropriately set the refractive index of the transparent substance in consideration of this point.

か ら Thus, the tip member of the present embodiment satisfies conditional expression (1). By satisfying conditional expression (1), generation of flare light on the outer peripheral surface can be suppressed.

When the value exceeds the upper limit value of the conditional expression (1), the refractive index difference becomes large. In this case, the light intensity of light reflected by Fresnel reflection increases. Therefore, it becomes difficult to suppress generation of flare light.

If the value is below the lower limit value of the conditional expression (1), the strength and the transparency of the tip member decrease. Therefore, the practicality is reduced.

先端 As described above, when observing an object, the tip optical system comes into contact with the object. If the strength of the tip member is low, the outer peripheral surface is damaged by the impact at the time of contact. In some cases, the tip optical system may be pushed toward the object. If the strength of the tip member is low, the outer peripheral surface is damaged by friction with the object. In addition, if the transparency of the tip member is low, the object cannot be clearly observed.

透明 Examples of the transparent substance satisfying the conditional expression (1) include quartz glass, fluorine resin, polyurethane, and hard vinyl.

Also, when the space between the inner surface and the holding member is filled with air, the refractive index greatly changes at the inner surface. Therefore, flare light is likely to be generated even on the inner surface.

There are two areas on the inner surface. One area is an area through which the illumination light passes. The other region is a region through which the imaging light passes. Flare light is more likely to occur as the overlap between the two regions increases.

In order to suppress the generation of flare light on the inner surface, the overlap between the two regions may be reduced. The overlap between the two regions decreases as the distance between the inner surface and the holding member decreases. Therefore, it is important to bring the inner surface close to the holding member.

か ら Thus, the tip member of the present embodiment satisfies conditional expression (2). By satisfying conditional expression (2), generation of flare light on the inner surface can be suppressed.

Conditional expression (2) is a conditional expression representing the distance between the inner surface and the holding member. The closer the value is to 1, the closer the inner surface and the holding member are.

FIGS. 5 and 6 are diagrams showing parameters used in conditional expressions. FIG. 5A is a diagram illustrating a first example of the inner surface. FIG. 5B is a diagram illustrating a second example of the inner surface. FIG. 6 is a diagram illustrating a third example of the inner surface. The same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

で は In the first example, the endoscope optical system 30 has the distal end member 31 and the imaging optical system 3. The tip member 31 has a tip optical system 32.

The tip optical system 32 has an outer peripheral surface 32a and an inner surface 32b. One end PE of the outer peripheral surface 32a is located on the optical axis AX. The inner surface 32b is located closer to the holding member 6 than the position of the one end PE.

The inner surface 32b has a first inner surface 32b1, a second inner surface 32b2, and a third inner surface 32b3. The first inner surface 32b1 and the third inner surface 32b3 are flat surfaces. The second inner surface 32b2 is a side surface of the truncated cone.

The first inner surface 32b1 includes the optical axis AX. The second inner surface 32b2 is located outside the first inner surface 32b1. The third inner surface 32b3 is located outside the second inner surface 32b2.

The tip member 31 is connected to the holding member 6 via the third inner surface 32b3. Therefore, the first region is formed by the third inner surface 32b3.

L is the distance from one end PE to the first intersection P1. The first intersection point P1 is an intersection point between the predetermined line PL and the optical axis AX. The predetermined line PL is a straight line that is in contact with the other end PE ′ of the outer peripheral surface 32a and that is orthogonal to the optical axis AX.

D is the distance from one end PE to the second intersection P2. The second intersection P2 is an intersection between the inner surface 32b and the optical axis AX. In the first example, the first inner surface 32b1 includes the optical axis AX. Therefore, the second intersection P2 is an intersection between the first inner surface 32b1 and the optical axis AX.

で は In the first example, the second intersection P2 is closer to one end PE than the first intersection P1. In this case, since d <L, 1 <L / d.

で は In the second example, the second intersection P2 coincides with the first intersection P1. In this case, since d = L, L / d = 1.

で は In the third example, the endoscope optical system 40 has a tip member 41 and an imaging optical system 42. The tip member 41 has a tip optical system 43. The imaging optical system 42 has a lens 42a and a lens 42b.

The tip optical system 43 has an outer peripheral surface 43a and an inner surface 43b. One end PE of the outer peripheral surface 43a is located on the optical axis AX. The inner surface 43b is located closer to the holding member 6 than the position of the one end PE.

The inner surface 43b has a first inner surface 43b1, a second inner surface 43b2, and a third inner surface 43b3. The first inner surface 43b1 is a curved surface. The second inner surface 43b2 is a cylindrical surface. The third inner surface 43b3 is a flat surface.

The first inner surface 43b1 includes the optical axis AX. The second inner surface 43b2 is located outside the first inner surface 43b1. The third inner surface 43b3 is located outside the second inner surface 43b2.

The tip member 41 is connected to the holding member 6 via the third inner surface 43b3. Therefore, the first region is formed by the third inner surface 43b3.

で は In the third example, the first inner surface 43b1 and the second inner surface 43b2 form a lens. In the endoscope optical system 40, the lens 42a is formed integrally with the distal end optical system 43. Further, the first inner surface 43b1 includes the optical axis AX. Therefore, the second intersection P2 is an intersection between the first inner surface 43b1 and the optical axis AX.

で は In the third example, the second intersection point P2 is farther from the one end PE than the first intersection point P1. In this case, since d> L, L / d <1.

で は In the first example, the illumination light emitted from the illumination unit 12 is applied to the first inner part 32b1. In the second example, the illumination light emitted from the illumination unit 12 is applied to the inner surface 4b. In the third example, the illumination light emitted from the illumination unit 12 is applied to the third inner 43b3.

で は In the first example, a space is formed between the emission end surface of the illumination unit 12 and the first inner surface 32b1. Therefore, an overlap occurs between the passage area of the illumination light and the passage area of the imaging light. In this case, a part of the illumination light reflected by the first inner surface 32b1 goes to the field of view of the imaging optical system.

In contrast, in the second example, no space is formed between the emission end face of the illumination unit 12 and the inner surface 4b. Therefore, no overlap occurs between the passage area of the illumination light and the passage area of the imaging light. In this case, the illumination light reflected by the inner surface 4b does not go to the visual field of the imaging optical system. As a result, flare light is less likely to be generated in the second example than in the first example. Also in the third example, as in the second example, flare light is less likely to be generated than in the first example.

By thus bringing the inner surface close to the holding member, it is possible to separate the passage area of the illumination light from the passage area of the imaging light. That is, the effect of suppressing the generation of flare light on the inner surface can be enhanced.

If the value is below the lower limit of conditional expression (2), the inner surface is located closer to the imaging optical system than the end surface of the holding member, and the distance between the inner surface and the holding member is too large. Therefore, it is difficult to easily connect the distal end member and the holding member.

If the value を exceeds the upper limit value of the conditional expression (2), the inner surface is located at one end side from the end surface of the holding member, and the distance between the inner surface and the holding member is too large. In this case, it is difficult to sufficiently separate the passing area of the illumination light and the passing area of the imaging light. Therefore, generation of flare light on the inner surface cannot be suppressed.

で は In the tip member of the present embodiment, the outer peripheral surface is preferably a surface including the side surface of the truncated cone.

FIG. 7 is a diagram showing a first example of the outer peripheral surface. FIG. 8 is a diagram illustrating a second example of the outer peripheral surface.

で は In the first example, the endoscope optical system 50 has the distal end member 51 and the imaging optical system 3. The tip member 51 has a tip optical system 52. The tip optical system 52 has an outer peripheral surface 52a and an inner surface 52b.

The outer peripheral surface 52a has a conical surface and a cylindrical surface. The inner surface 52b is a flat surface. A portion of the conical surface can be considered as the side of the truncated cone. Thus, the outer peripheral surface 52a is a surface including the side surface of the truncated cone.

で は In the second example, the endoscope optical system 55 has the distal end member 56 and the imaging optical system 3. The tip 56 has a tip optical system 57. The tip optical system 57 has an outer peripheral surface 57a and an inner surface 57b.

The outer peripheral surface 57a has a hemispherical surface, a side surface of a truncated cone, and a cylindrical surface. The inner surface 57b is a flat surface. The side of the truncated cone is part of the cone 58. Thus, the outer peripheral surface 57a is a surface including the side surface of the truncated cone.

In FIG. 8, the hemisphere is drawn large for easy viewing. However, the ratio of the hemispherical surface to the outer peripheral surface 57a is preferably as small as possible.

外 周 As described above, the outer peripheral surface is located near the object, or the outer peripheral surface is in close contact with the object. In this case, the outer peripheral surface comes into contact with a liquid, for example, water, or comes into contact with an object. The refractive index of water or the refractive index of an object is greater than one. In this case, the Fresnel reflectance on the outer peripheral surface is low. Therefore, generation of flare light on the outer peripheral surface is small. However, when the outer peripheral surface is a hemispherical surface, generation of flare light increases. For this reason, observation is hindered.

For example, the tip member can be attached to the insertion portion of the endoscope. In the endoscope, the tip member is used in the air until the tip member reaches the object. When the tip member is used in the air, the Fresnel reflectance on the outer peripheral surface is high. In this case, strong flare light is generated. Therefore, it is difficult to smoothly operate the endoscope until the distal end member reaches the object.

で は In the tip member of the present embodiment, the outer peripheral surface includes the side surface of the truncated cone. Therefore, generation of flare light can be suppressed even when the tip member is in the air. As a result, the operation of the endoscope can be performed smoothly.

In the tip member according to the present embodiment, the truncated cone is preferably a part of a cone satisfying the following conditional expression (3).
0 ° <θ <40 ° (3)
Where θ is the cone apex angle,
It is.

In the first example of the outer peripheral surface shown in FIG. 7, the cone forming the outer peripheral surface 52a is a cone that satisfies the conditional expression (3). Therefore, in the tip member 51, the truncated cone is a part of the cone satisfying the conditional expression (3). In the second example of the outer peripheral surface shown in FIG. 8, the cone 58 is a cone satisfying the conditional expression (3). Therefore, in the tip member 56, the truncated cone is a part of the cone satisfying the conditional expression (3).

As described above, in the tip member of the present embodiment, the truncated cone is a part of the cone satisfying the conditional expression (3). Therefore, the occurrence of flare can be further suppressed.

If the value exceeds the upper limit of conditional expression (3), the number of reflections of the illumination light on the outer peripheral surface is likely to be three. In this case, since the illumination light easily enters the imaging optical system, flare easily occurs.

FIG. 9 is a graph showing the relationship between the magnitude of flare light and the apex angle of a cone. The vertical axis is the peak irradiance of flare light (Watts / cm ² ). The horizontal axis is the angle of the apex of the cone. The unit of irradiance is Watts / cm ² , and the unit of apex angle is degree.

The magnitude of flare light is determined by simulation. In the simulation, the outer peripheral surface is assumed to be a conical surface.

大 き The magnitude of flare light is calculated based on ray tracing. Of the illumination light reflected on the outer peripheral surface, the magnitude of flare light is calculated based on light rays that pass through the imaging optical system and reach the image plane.

The flare light depends on the shape of the illumination unit and the relative position between the illumination unit and the imaging optical system. The simulation was performed for concentric arrangement and parallel arrangement. In the concentric arrangement, as shown in FIG. 2, the imaging optical system and the illumination unit are arranged concentrically. In the parallel arrangement, as shown in FIG. 3, the image forming optical system and the illumination unit are arranged in parallel.

The solid line indicates the simulation result in the concentric arrangement. The broken line shows the simulation result in the parallel arrangement. In the parallel arrangement, the distance between the imaging optical system and the illumination unit is 0.4 mm.

か ら From the graph shown in FIG. 9, it can be seen that if the vertex angle θ of the cone on the outer peripheral surface is 40 ° or less, the generation of flare light on the outer peripheral surface can be suppressed. Further, when the vertex angle θ of the cone on the outer peripheral surface is 20 ° or less, even if Fresnel reflection occurs on the outer peripheral surface, the flare light incident on the imaging optical system is very small.

It is preferable to satisfy the following conditional expression (3-1) instead of conditional expression (3).
0 ° <θ <20 ° (3-1)

In the tip member according to the present embodiment, the truncated cone is preferably a part of a cone satisfying the following conditional expression (3 ′).
60 ° <θ <70 ° (3 ')
Where θ is the cone apex angle,
It is.

わ か る As can be seen from the graph shown in FIG. 9, in the parallel arrangement, the vertex angle θ of the cone on the outer peripheral surface is 65 °, and the flare light decreases. In the parallel arrangement, the occurrence of flare light on the outer peripheral surface can be suppressed by satisfying conditional expression (3 ').

When the value is below the lower limit value of the conditional expression (3 ′), the number of reflections of the illumination light on the outer peripheral surface is likely to be three. In this case, since the illumination light easily enters the imaging optical system, flare easily occurs. When the value exceeds the upper limit value of the conditional expression (3 '), the number of reflections of the illumination light on the outer peripheral surface is likely to be two. In this case, since the illumination light easily enters the imaging optical system, flare easily occurs.

It is preferable that the tip member satisfying the conditional expression (3 ′) is combined with an imaging optical system satisfying the following conditional expression.
0 ° <2ω ≦ 70 °
here,
ω is the half angle of view of the imaging optical system,
It is.

In the distal end member of the present embodiment, the truncated cone is preferably a part of a cone satisfying the following conditional expression (3 ″).
110 ° <θ <180 ° (3 ”)
Where θ is the cone apex angle,
It is.

わ か る As can be seen from the graph shown in FIG. 9, in the parallel arrangement, flare light decreases when the vertex angle θ of the cone on the outer peripheral surface is 110 ° or more. In the concentric arrangement, flare light is reduced when the vertex angle θ of the cone on the outer peripheral surface is 120 ° or more.

If the value is below the lower limit of the conditional expression (3 ″), the vertex angle θ of the cone on the outer peripheral surface becomes close to 90 °, and therefore, the number of reflections of the illumination light on the outer peripheral surface is likely to be two. Since the illumination light easily enters the imaging optical system, flare easily occurs.

It is preferable that the following conditional expression (3 ″ -1) or (3 ″ -2) is satisfied instead of conditional expression (3 ″).
120 ° <θ (3 ”-1)
110 ° <θ <180 ° (3 ”-2)

In the tip member according to the present embodiment, the inner surface has a first region and a second region including an optical axis, and the second region includes a predetermined surface, and the predetermined surface includes the first surface. It is preferable to be located on one end side of the outer peripheral surface with respect to the region and satisfy the following conditional expression (4).
0 (1 / mm) ≦ C <5 (1 / mm) (4)
here,
C is the reciprocal of the predetermined interval,
The predetermined interval is an interval between the paraxial center of curvature of the predetermined surface and the first intersection,
It is.

で は In the tip member of the present embodiment, the inner surface has a first region and a second region including the optical axis.

The second area includes a predetermined surface. The predetermined surface is a flat surface or a curved surface. The predetermined surface can be represented by the magnitude of the paraxial curvature. When the paraxial curvature is infinite, the predetermined plane is a plane. In a plane, the paraxial center of curvature is located at infinity.

If the paraxial curvature is finite, the curved surface is a spherical surface or a surface that can be approximated by a spherical surface. An example of a surface that can be approximated by a spherical surface is an aspherical surface.

す る と When the tip member is connected to the holding member, the predetermined surface faces the imaging optical system. The predetermined surface is located closer to one end of the outer peripheral surface than the first region. Therefore, a space (hereinafter, referred to as “space A”) is formed between the predetermined surface and the imaging optical system.

場合 When the space A is filled with air, the illumination light is reflected on a predetermined surface. When the illumination light is reflected on a predetermined surface, a part of the illumination light enters the imaging optical system. Therefore, flare light is easily generated.

Conditional expression (4) is a conditional expression representing how far the paraxial center of curvature of the predetermined surface is away from the first region. By satisfying conditional expression (4), generation of flare light can be suppressed even when the inner surface has a predetermined surface.

FIG. 10 is a diagram showing parameters used in the conditional expression. As described later, the tip member may have a holding frame. Here, a description will be given using a tip member having a holding frame.

The tip member 60 has a tip optical system 61 and a holding frame 62. The tip optical system 61 and the holding frame 62 are integrally formed. The tip optical system 61 has an outer peripheral surface 61a and an inner surface 61b.

The outer peripheral surface 61a has a conical surface and a cylindrical surface. The inner surface 61b has a first inner surface 61b1, a second inner surface 61b2, and a third inner surface 61b3. The first inner surface 61b1 is a curved surface. The second inner surface 61b2 is a cylindrical surface. The third inner surface 61b3 is a flat surface.

The second inner surface 61b2 is located outside the first inner surface 61b1. The third inner surface 61b3 is located outside the second inner surface 61b2.

The third inner surface 61b3 is in contact with the end surface of the holding member 6. Therefore, the first region is formed by the third inner surface 61b3. Further, the first inner surface 61b1 includes the optical axis AX. Therefore, the second region is formed by the first inner surface 61b1. The second inner surface 61b2 can be included in the second region.

The first inner surface 61b1 is located at one end PE side of the third inner surface 61b3. In a state where the optical axis AX coincides with the optical axis of the imaging optical system, the first inner surface 61b1 faces the imaging optical system.

The first inner surface 61b1 is a predetermined surface. As described above, the predetermined surface is a flat surface or a curved surface. In the tip optical system 61, the first inner surface 61b1 is a curved surface. The first inner surface 61b1 includes a spherical surface 63. The center of the paraxial curvature of the spherical surface 63 is located on the optical axis AX. In FIG. 10, the position of the paraxial curvature center is indicated by P3.

C is the reciprocal of the predetermined interval Δ. The predetermined interval Δ is an interval between the position P3 and the first intersection P1. The first intersection point P1 is an intersection point between the predetermined line PL and the optical axis AX. The predetermined line PL is a straight line that is in contact with the other end PE ′ and is orthogonal to the optical axis AX.

で は In the tip optical system 61, the predetermined line PL overlaps the third inner surface 61b3. As described above, the third inner surface 61b3 is a surface that forms the first region. Therefore, it can be said that the predetermined line PL is a straight line that is in contact with the first region and is orthogonal to the optical axis AX.

When the value exceeds the upper limit value of the conditional expression (4), a part of the illumination light reflected on the inner surface 61 b directly enters the imaging optical system 3. Thus, flare light is generated by one reflection. As a result, flare occurs in the field of view. Further, since the number of reflections is one, particularly strong flare occurs.

For example, when C = ∞, Δ = 0. When Δ = 0, the paraxial center of curvature of the predetermined surface coincides with the third intersection. In this case, the angle of view in the space A and the angle of view in the tip optical system can be made the same. However, the illumination light reflected on the predetermined surface is all incident on the imaging optical system. When the value exceeds the upper limit value of the conditional expression (4), the state approaches C = ∞. Therefore, it is not preferable that the value exceeds the upper limit of conditional expression (4).

It is preferable that the following conditional expression (4 ′) is satisfied instead of conditional expression (4).
0 (1 / mm) ≦ C <0.1 (1 / mm) (4 ′)

When the condition (4 ') is satisfied, the paraxial center of curvature of the curved surface can be separated from the first intersection by 10 mm or more. As a result, flare light incident on the imaging optical system can be reduced.

場合 When the tip optical system and the holding frame are integrally formed, the boundary between the tip optical system and the holding frame, that is, the other end of the tip optical system does not physically exist. In this case, the other end of the tip optical system can be determined based on, for example, the first region. The first region is located on the same plane as the other end of the tip optical system. The virtual plane is a plane that includes the first region and is orthogonal to the optical axis. The other end of the tip optical system is an intersection between the virtual surface and the outer peripheral surface.

It is preferable that the tip member of the present embodiment satisfies the following conditional expression (5).
0 <L / D <1.5 (5)
here,
L is the distance from one end to the first intersection,
D is the outer diameter of the tip optical system,
A first intersection is an intersection between a predetermined line and the optical axis,
The predetermined line is a straight line that is in contact with the other end of the outer peripheral surface and is orthogonal to the optical axis;
It is.

Conditional expression (5) is a conditional expression relating to the hard length. In particular, when the endoscope optical system according to the present embodiment is used for a flexible endoscope, it is preferable to satisfy the conditional expression (5).

FIG. 11 is a diagram showing parameters used in the conditional expression. The same components as those in FIG. 7 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 11, the tip member 51 and the holding member 6 are illustrated in a separated state for easy viewing.

The endoscope optical system 50 has the distal end member 51 and the imaging optical system 3. The tip member 51 has a tip optical system 52. The tip optical system 52 has an outer peripheral surface 52a and an inner surface 52b. The outer peripheral surface 52a has a conical surface and a cylindrical surface. The inner surface 52b is a flat surface.

Ｌ As described above, L is the distance from one end PE to the first intersection P1. D is the outer diameter of the tip optical system 52. The outer diameter of the tip optical system 52 can be regarded as the cross-sectional length of the outer peripheral surface 52a. The cross-sectional length of the outer peripheral surface 52a may vary depending on the position in the optical axis direction. In this case, the maximum cross-sectional length among the cross-sectional lengths of the outer peripheral surface 52a may be set to the outer diameter of the tip optical system 52.

As described above, the flexible endoscope is used, for example, for bronchial observation, blood vessel observation, and urology observation. The flexible endoscope is also used for observation and inspection in otolaryngology. In these observations, the objects are often thin, meandering lumens.

で By satisfying conditional expression (5), the total length of the tip optical system is shortened. In this case, for example, the hard length of the flexible endoscope can be shortened. If the hard length can be shortened, a large bending angle can be obtained with a small turning radius. Therefore, when inserting the flexible endoscope into the lumen, the distal end of the endoscope can easily reach the end of the object.

If the value exceeds the upper limit of conditional expression (5), the entire length of the tip optical system becomes longer. In this case, the rigid length of the flexible endoscope becomes longer. Therefore, the distal end of the endoscope cannot reach the end of the bronchus or the end of the blood vessel.

It is preferable that the tip member of the present embodiment satisfies the following conditional expression (5 ′).
1.5 <L / D <10 (5 ′)
here,
L is the distance from one end to the first intersection,
D is the outer diameter of the tip optical system,
A first intersection is an intersection between a predetermined line and the optical axis,
The predetermined line is in contact with the other end region of the outer peripheral surface, and is a straight line orthogonal to the optical axis;
It is.

Conditional expression (5 ') is a conditional expression relating to the hard length. In particular, when the endoscope optical system according to the present embodiment is used for a rigid endoscope, it is preferable to satisfy the conditional expression (5 ').

If the conditional expression (5 ') is satisfied, the total length of the tip optical system becomes longer. As the total length of the tip optical system increases, the hard length increases. In particular, in the case of a rigid endoscope, an instrument used for a surgical operation, or an instrument used for puncturing, the endoscope or the instrument is moved linearly. If the hard length is long, linear movement can be performed stably.

In the tip member according to the present embodiment, the inner surface has a first region and a second region including an optical axis, the second region includes a predetermined surface, and the predetermined surface is the first region. More preferably, it is located on one end side of the outer peripheral surface.

FIG. 12 is a diagram showing a tip member of the present embodiment. The same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

The endoscope optical system 70 includes the distal end member 71 and the imaging optical system 3. The tip member 71 has a tip optical system 72. The tip optical system 72 has an outer peripheral surface 72a and an inner surface 72b.

The outer peripheral surface 72a has a conical surface and a cylindrical surface. The inner surface 72b has a first inner surface 72b1, a second inner surface 72b2, and a third inner surface 72b3. The first inner surface 72b1 and the third inner surface 72b3 are flat surfaces. The second inner surface 72b2 is a cylindrical surface.

The second inner surface 72b2 is located outside the first inner surface 72b1. The third inner surface 72b3 is located outside the second inner surface 72b2.

で は In the tip optical system 72, the third inner surface 72b3 is in contact with the end surface of the holding member 6. Therefore, the first region is formed by the third inner surface 72b3. Further, the first inner surface 72b1 includes the optical axis AX. Therefore, the second region is formed by the first inner surface 72b1. The second inner surface 72b2 can be included in the second region.

The first inner surface 72b1 is located closer to one end of the outer peripheral surface 72a than the third inner surface 72b3. When the optical axis and the optical axis of the imaging optical system match, the first inner surface 72b1 faces the imaging optical system 3.

The first inner surface 72b1 is a predetermined surface. The predetermined surface is a flat surface or a curved surface. In the tip optical system 72, the first inner surface 72b1 is a flat surface.

When the tip member 71 is connected to the holding member 6, a space A is formed between the first inner surface 72b1 and the imaging optical system 3. The space A is surrounded by the first inner surface 72b1, the second inner surface 72b2, the parallel flat plate 5, and the end surface of the holding member 6. As described below, the space A can be filled with the liquid 73, for example.

先端 The distal end member of the present embodiment preferably has a holding frame, and the holding frame is preferably located at the other end of the outer peripheral surface.

FIG. 13 is a diagram showing a first example of the tip member. The tip member 80 has a tip optical system 81 and a holding frame 82. The tip optical system 81 and the holding frame 82 are integrally formed.

The tip optical system 81 has an outer peripheral surface 81a and an inner surface 81b. The outer peripheral surface 81a has a first outer peripheral surface 81a1 and a second outer peripheral surface 81a2. The first outer peripheral surface 81a1 is a hemispherical surface. The second outer peripheral surface 81a2 is a cylindrical surface. The inner surface 81b is a flat surface.

The holding frame 82 has an outer peripheral surface 82a and an inner peripheral surface 82b. The outer peripheral surface 82a and the inner peripheral surface 82b are cylindrical surfaces.

FIG. 14 is a diagram showing a second example of the distal end member. The tip member 90 has a tip optical system 91 and a holding frame 82. The tip optical system 91 and the holding frame 82 are integrally formed. Since the holding frame 82 is the same as that of the first example, the description is omitted.

The tip optical system 91 has an outer peripheral surface 91a and an inner surface 91b. The outer peripheral surface 91a has a first outer peripheral surface 91a1 and a second outer peripheral surface 91a2. The first outer peripheral surface 91a1 is a hemispherical surface. The second outer peripheral surface 91a2 is a side surface of a truncated cone.

FIG. 15 is a view showing a third example of the tip member. The tip member 100 has a tip optical system 101 and a holding frame 102. The tip optical system 101 and the holding frame 102 are integrally formed.

The tip optical system 101 has an outer peripheral surface 101a and an inner surface 101b. The outer peripheral surface 101a has a first outer peripheral surface 101a1 and a second outer peripheral surface 101a2. The first outer peripheral surface 101a1 is a hemispherical surface. The second outer peripheral surface 101a2 is a side surface of a truncated cone. The inner surface 101b is a flat surface.

The holding frame 102 has an outer peripheral surface 102a and an inner peripheral surface 102b. The outer peripheral surface 102a is a side surface of a truncated cone. The inner peripheral surface 102b is a cylindrical surface. The shape of the holding frame 112 is a tapered shape.

FIG. 16 is a view showing a fourth example of the tip member. The tip member 110 has a tip optical system 111 and a holding frame 112. The tip optical system 111 and the holding frame 112 are integrally formed.

The tip optical system 111 has an outer peripheral surface 111a and an inner surface 111b. The outer peripheral surface 111a is an elliptical surface. The inner surface 111b is a flat surface.

The holding frame 112 has an outer peripheral surface 112a and an inner peripheral surface 112b. The outer peripheral surface 112a is an elliptical surface. The inner peripheral surface 112b is a cylindrical surface. The shape of the holding frame 112 is a tapered shape.

FIG. 17 is a diagram showing a fifth example of the tip member. The tip member 120 has a tip optical system 81 and a holding frame 121. The tip optical system 81 and the holding frame 121 are integrally formed. Since the tip optical system 81 is the same as that of the first example, the description is omitted.

The holding frame 121 has an outer peripheral surface 121a and an inner peripheral surface 121b. The outer peripheral surface 121a is a cylindrical surface. The shape of the inner peripheral surface 121b is a shape in which a screw is formed on a cylindrical surface.

FIG. 18 is a diagram showing a sixth example of the distal end member. The tip member 130 has a tip optical system 131.

The tip optical system 131 has an outer peripheral surface 131a and an inner surface 131b. The outer peripheral surface 131a has a first outer peripheral surface 131a1 and a second outer peripheral surface 131a2. The first outer peripheral surface 131a1 is a hemispherical surface. The second outer peripheral surface 131a2 is a cylindrical surface.

The inner surface 131b is a flat surface, and the metal film 132 is formed on the surface. The tip member 130 can be connected to the holding member by soldering or metal brazing.

内 It is preferable that the endoscope optical system of the present embodiment include the distal end member of the present embodiment and an imaging optical system arranged on the holding member.

As shown in FIG. 1, the endoscope optical system 1 has a distal end member 2 and an imaging optical system 3. The imaging optical system 3 is held by a holding member 6. The endoscope optical system 1 is formed by connecting the distal end member 2 and the holding member 6.

In the endoscope optical system according to the present embodiment, the first region is a region formed by a plane, the end surface of the holding member in contact with the first region is a plane, and the two planes are The plane is preferably orthogonal to the optical axis.

こ と Thus, the tip member and the holding member can be easily and accurately connected. An imaging optical system is held by the holding member. If the tip member and the holding member can be connected with high accuracy, the eccentricity generated between the tip member and the imaging optical system can be reduced. As a result, occurrence of various aberrations can be suppressed. Further, it is possible to obtain a desired visual field and a desired optical performance.

(4) When the tip member can be attached to and detached from the holding member, the optical performance is reduced even if attachment and detachment are repeated. Further, even if the tip member is replaced with another tip member, a desired visual field and a desired optical performance can be obtained.

The inner surface can have a first region and a second region including the optical axis. In this case, the second region can also be a region formed by a plane. In this case, the entire inner surface becomes a plane. By doing so, the tip member and the holding member can be easily and accurately connected.

The second region can be a region formed by a curved surface. However, when the curvature of the curved surface is large, the eccentricity generated between the tip member and the imaging optical system increases. In this case, in order to connect the tip member and the holding member with high accuracy, the connection mechanism needs to have high accuracy. Therefore, it is preferable to use a curved surface having a small curvature.

In the endoscope optical system of the present embodiment, the inner surface has a first region and a second region including an optical axis, and the second region includes a predetermined surface, and the predetermined surface is It is preferable that a refractive index difference suppression unit is provided on one end side of the outer peripheral surface with respect to the first area and between the predetermined surface and the imaging optical system.

で は In the endoscope optical system of the present embodiment, the tip member 71 shown in FIG. 12 can be used. As shown in FIG. 12, when the tip member 71 is connected to the holding member 6, a space A is formed between the first inner surface 72b1 and the imaging optical system 3. The space A is surrounded by the first inner surface 72b1, the second inner surface 72b2, the parallel flat plate 5, and the end surface of the holding member 6.

場合 When the space A is filled with air, light rays exceeding the critical angle do not enter the imaging optical system. For example, when the tip optical system is formed of a material having a refractive index of 1.51, the critical angle is 41 °. Therefore, in the tip optical system, a light ray having a half angle of view of 41 ° or more cannot be incident on the imaging optical system.

Therefore, a space A is provided with a refractive index difference suppressing portion. In this manner, a light ray having an angle of view of 41 ° or more can be made incident on the imaging optical system. As a result, the field of view can be further expanded.

で は In the endoscope optical system of the present embodiment, it is preferable that the refractive index difference suppressing section is filled with a liquid having a refractive index of 1.3 or more.

By filling the space A with the liquid 73, total reflection on the first inner surface 72b1 can be prevented. The liquid 73 preferably has a refractive index of 1.3 or more. For example, water can be used as the liquid 73.

臨界 When the space A is filled with water, the critical angle becomes 61 °. In this case, light rays having an angle of view of up to 61 ° can be incident on the imaging optical system. As a result, a field of view with a total angle of view of 122 ° can be realized.

　ｒ_ｉは、ｉ番目の透過面の曲率半径、
　ｎ’_ｉは、ｉ番目の透過面の射出側における屈折率、
　ｎ_ｉは、ｉ番目の透過面の入射側における屈折率、
　ｎ’は、像空間の屈折率、
　ｉは、透過面の番号、
　ｋは、透過面の総数、
である。 In the endoscope optical system according to the present embodiment, it is preferable that the imaging optical system includes only the transmission surface, has a field curvature aberration, and satisfies the following conditional expression (6).
-10 <P '<-0.8 (6)
Here, P ′ is a Petzval sum and is represented by the following equation:

r _i is the radius of curvature of the i-th transmission surface,
n ′ _i is the refractive index on the exit side of the i-th transmission surface,
_ni is the refractive index on the incident side of the i-th transmission surface;
n ′ is the refractive index of the image space,
i is the number of the transmission surface,
k is the total number of transmission surfaces,
It is.

As shown in FIG. 1, the endoscope optical system 1 has a distal end member 2 and an imaging optical system 3. The imaging optical system 3 includes only a transmission surface. The tip member 2 has a tip optical system 4. The tip optical system 4 has an outer peripheral surface 4a and an inner surface 4b.

As described above, in an environment where an opaque substance exists between the object and the imaging optical system, light incident on the imaging optical system from the object decreases. Therefore, it is difficult to clearly observe the object.

で も In order to clearly observe an object even in such an environment, it is necessary to reduce the number of opaque substances or eliminate the opaque substances. When the tip optical system 4 is used, the outer peripheral surface 4a may be located near the object, or the outer peripheral surface 4a may be brought into close contact with the object. In this manner, the number of opaque substances can be reduced or the opaque substances can be eliminated. As a result, the object can be clearly observed.

観 察 In observing an object using the endoscope optical system 1, the tip optical system 4 is moved closer to the object. When the tip optical system 4 contacts the object, the tip optical system 4 is further pushed. When the shape of the outer peripheral surface 4a is tapered, the distal end optical system 4 can be easily pushed toward the object.

(4) When the tip optical system 4 is pushed toward the object, the opaque substance is pushed away because the object approaches the tip optical system 4. That is, opaque substances are excluded. As a result, the outer peripheral surface 4a can be located near the object, or the outer peripheral surface 4a can be brought into close contact with the object.

In a normal optical system, it is assumed that the object plane is a plane perpendicular to the optical axis. For observation of an object, an image sensor can be used. Normally, the imaging surface of the imaging device is a flat surface and is located perpendicular to the optical axis. For this reason, in a general optical system, occurrence of field curvature aberration is suppressed.

On the other hand, in the endoscope optical system 1, the object plane is located near the outer peripheral surface 4a or on the outer peripheral surface 4a. Since the outer peripheral surface 4a has a tapered shape, the object surface is parallel to the outer peripheral surface 4a. In this case, the object plane does not become a plane perpendicular to the optical axis. Therefore, it is preferable that the imaging optical system 3 has a curvature of field.

FIG. 19 is a diagram showing an image forming relationship of an optical system having a field curvature aberration. FIG. 19A shows a case where the object surface is a plane, and FIG. 19B shows a case where the object surface is a curved surface.

The sign of the Petzval sum indicates the direction in which the curvature of field occurs, and the value indicates the amount of occurrence of the curvature of field. Generally, in an optical system having a positive refractive power, the sign of the Petzval sum is negative. In an optical system in which the sign of the Petzval sum is minus, as shown in FIG. 19A, when the object plane OB is a plane, a curved surface with a concave surface facing the object side is formed on the image plane I.

In an optical system, the object and the image can be reversed. Therefore, when the object plane OB in FIG. 19A is regarded as an image plane and the image plane I is regarded as an object plane, as shown in FIG. 19B, the object plane OB is a curved surface with a concave surface facing the image side. become. On the other hand, the image plane I becomes a plane. As described above, in an optical system in which the sign of the Petzval sum is minus, a curved object can be formed on a plane. It is preferable that the object surface OB be a curved surface with the concave surface facing the image side, since the focusing range is widened.

で は In the endoscope optical system of the present embodiment, an optical system in which the sign of the Petzval sum is minus is used for the imaging optical system 3. Since the imaging optical system 3 has a curvature of field, an image of the object surface can be formed on a plane even if the object surface is a curved surface.

In order to form a clear image of the object in a wider range, it is desirable that the imaging optical system 3 generate an appropriate amount of curvature of field. That is, it is desirable to make the value of Petzval sum appropriate.

In the endoscope optical system according to the present embodiment, an image of an object is formed via a liquid. Therefore, it is desirable that the value of the Petzval sum in the imaging optical system 3 be determined in consideration of the fact that an image of the object is formed via the liquid.

In the endoscope optical system of the present embodiment, an image of an object is formed with the object surface along the outer peripheral surface 4a. Therefore, it is desirable that the value of the Petzval sum in the imaging optical system 3 be determined in consideration of the fact that an image of an object is formed with the object surface along the outer peripheral surface 4a.

か ら Thus, the endoscope optical system of the present embodiment satisfies the conditional expression (6). Conditional expression (6) indicates the curvature of the image plane when there is no astigmatism. By satisfying conditional expression (6), a clear image can be formed from the center to the periphery of the visual field.

In the endoscope optical system of the present embodiment, the value of the Petzval sum is such that the space from the object to the imaging optical system 3 and the space from the imaging optical system 3 to the image are both filled with air. It is calculated by In calculating the Petzval sum, the distal end optical system 4 is excluded from the endoscope optical system 1. Therefore, the value of Petzval sum is calculated only from the imaging optical system 3.

If the value is below the lower limit of conditional expression (6), the curvature on the object plane will be too large. In this case, the curvature toward the image side becomes excessive in the peripheral portion of the object plane. That is, each point in the peripheral portion is shifted from the optimum object point position.

(4) If each point on the object plane matches the optimum position, the image of the object plane formed on the image plane becomes a plane. However, when each point in the peripheral portion deviates from the optimum object point position, the image of the object formed on the image plane does not become a plane. As a result, a clear image cannot be formed from the center of the visual field to the periphery.

When the value exceeds the upper limit value of the conditional expression (6), the curvature on the object surface becomes too small. In this case, the curvature toward the image side is insufficient around the object facing surface. That is, each point in the peripheral portion is shifted from the optimum object point position. Therefore, a clear image cannot be formed from the center of the visual field to the periphery.

は In the endoscope optical system according to the present embodiment, the imaging optical system has a curvature of field, and satisfies the conditional expression (6). Therefore, an object located near the outer peripheral surface of the distal end optical system or an object in contact with the outer peripheral surface of the distal end optical system can be clearly observed.

先端 In the tip member of the present embodiment, the shape of the outer peripheral surface is tapered. However, in the tapered shape, the imaging light is obliquely incident on the outer peripheral surface. Therefore, aberration occurs.

The outer peripheral surface can be a surface having a symmetry axis. In this case, the outer peripheral surface becomes a rotationally symmetric surface with respect to the optical axis. An example of a rotationally symmetric surface with respect to the optical axis is a spherical surface. Aberrations occurring on a spherical surface are less complicated than aberrations occurring on a non-rotationally symmetric surface.

However, in the tip member of the present embodiment, the outer peripheral surface is not spherical. For example, the outer peripheral surface includes a tapered shape. For this reason, more complicated eccentric aberration occurs as compared with a spherical surface.

で は In a tapered shape, for example, a shape including a side surface of a truncated cone, the cross-sectional shape in a plane orthogonal to the optical axis is a circle. The radius of curvature of the circle changes in the optical axis direction. Particularly on the outer peripheral surface, the radius of curvature at one end is much smaller than the radius of curvature at the other end. Therefore, very large astigmatism occurs on the outer peripheral surface.

FIG. 20 is a diagram showing a virtual image when the object plane is a plane. FIG. 21 is a diagram illustrating a virtual image when the object surface is a curved surface. 20 and 21, the outer peripheral surface 4a is a side surface of a truncated cone. The object plane OB is separated from the entrance pupil of the imaging optical system 3 by 0.7 mm.

Light beam Lam, light beam Lbm, light beam Lcm, light beam Lam ', light beam Lbm', and light beam Lcm 'are light beams in a meridional section. The light beam Lbs and the light beam Lbs' are light beams in a sagittal section.

The light beam Lam, the light beam Lbm, the light beam Lcm, and the light beam Lbs are light beams that indicate the object plane OB. The light beam Lam ', the light beam Lbm', and the light beam Lcm 'are light beams showing a virtual image Imeri in the meridional section. The light beam Lbs' is a light beam showing a virtual image Isagi in a sagittal section.

The luminous flux Lam is a luminous flux when the angle of view is 9 °. The light beam Lbm and the light beam Lbs are light beams when the angle of view is 19 °. The light flux Lcm is a light flux when the angle of view is 29 °.

A case where the imaging optical system 3 has no field curvature aberration will be described with reference to FIG. When the object plane OB is a plane, as shown in FIG. 20, due to the aberration generated on the outer peripheral surface 4a, in the meridional section, as the angle of view becomes larger, the virtual image Imeri moves away from the entrance pupil of the imaging optical system 3. To go. Therefore, as the angle of view increases, the virtual image Imeri moves away from the outer peripheral surface 4a.

Further, on the outer peripheral surface 4a, the radius of curvature in the meridional section and the radius of curvature in the sagittal section are different. In this case, the convergence position PLbm 'of the light beam Lbm' is different from the convergence position of the light beam Lbs'. That is, astigmatism occurs. Therefore, the position of the virtual image Imeri is different from the position of the virtual image Isagi.

A case where the imaging optical system 3 has a curvature of field will be described with reference to FIG. In this case, the object surface OB can be regarded as a curved surface. Here, the object surface OB is a spherical surface having a radius of 0.4 mm with the concave surface facing the entrance pupil side.

In the case where the object surface OB is a curved surface, the object surface OB is curved along the outer peripheral surface 4a. In this case, each point on the object plane OB is located substantially along the outer peripheral surface 4a. As a result, the virtual image also becomes a curved surface with the convex surface facing the entrance pupil side of the imaging optical system 3.

As shown in FIG. 21, in the meridional section, as the angle of view increases, the virtual image Imeri approaches the entrance pupil of the imaging optical system 3. Therefore, as the angle of view increases, the virtual image Imeri approaches the outer peripheral surface 4a as compared to FIG.

As described above, the radius of curvature in the meridional section and the radius of curvature in the sagittal section are different on the outer peripheral surface 4a. In this case, the convergence position PLbm 'of the light beam Lbm' is different from the convergence position of the light beam Lbs'. That is, astigmatism occurs. Therefore, the position of the virtual image Imeri is different from the position of the virtual image Isagi.

However, when the imaging optical system 3 has field curvature aberration, the amount of astigmatism is smaller than that in FIG. 20, as shown in FIG. As described above, if the imaging optical system 3 is provided with the field curvature aberration, the shape of the virtual image can be made suitable for imaging. The shape suitable for imaging is a shape in which a clear image can be captured by a planar imaging device.

In addition, since the virtual image has a shape along the outer peripheral surface 4a, astigmatism generated by the outer peripheral surface 4a can be reduced.

分 か る As can be understood from the above description, when astigmatism is large, it is difficult to form a clear object image. In order to reduce astigmatism, it is preferable that the imaging optical system has a curvature of field. As described above, in the endoscope optical system according to the present embodiment, since the imaging optical system has the curvature of field, astigmatism can be reduced. As a result, a clear object image can be easily formed.

In the endoscope optical system of the present embodiment, the inner surface has a first region and a second region including an optical axis, and the second region has a curved surface with a concave surface facing the imaging optical system. It is preferred to have.

FIG. 22 is a cross-sectional view of the endoscope optical system according to the present embodiment. The endoscope optical system 140 has a tip member 141 and an imaging optical system 144.

The tip member 141 has a tip optical system 142 and a holding frame 143. The tip optical system 142 has an outer peripheral surface 142a and an inner surface 142b.

The outer peripheral surface 142a is a conical surface. The inner surface 142b has a first inner surface 142b1, a second inner surface 142b2, and a third inner surface 142b3. The first inner surface 142b1 and the second inner surface 142b2 are curved surfaces. The third inner surface 142b3 is a flat surface.

The second inner surface 142b2 is located outside the first inner surface 142b1. The third inner surface 142b3 is located outside the second inner surface 142b2.

で は In the tip optical system 142, the third inner surface 142b3 is in contact with the end surface of the holding member. Therefore, the first region is formed by the third inner surface 142b3. The first inner surface 142b1 includes the optical axis. Therefore, the second region is formed by the curved surface 142b1.

The first inner surface 142b1 has a concave surface facing the entrance pupil of the imaging optical system 144. Thus, the second region has a curved surface with the concave surface facing the imaging optical system side 144.

The first inner surface 142b1 can be a concave surface centered on the entrance pupil of the imaging optical system 144. In this case, a wide angle of view can be secured. Further, when the tip member 141 is detachable from the holding member, it is possible to eliminate a change in the angle of view due to the detachment.

The second inner surface 142b2 can be included in the second region. The second inner surface 142b2 has a concave surface facing the illumination unit. This makes it possible to increase the illumination angle of the illumination light.

(4) When the imaging optical system 144 and the illumination unit are arranged concentrically, the second inner surface 142b2 may be a toric surface.

Hereinafter, embodiments of the imaging optical system used in the endoscope optical system will be described in detail with reference to the drawings. The present invention is not limited by the embodiment.

FIG. 23 shows a lens cross-sectional view of the imaging optical system of the first embodiment. The imaging optical system according to the first embodiment includes a biconvex lens L1. The aperture stop S is arranged on the object side surface of the biconvex lens L1. It is preferable that the biconvex lens L1 is a ball lens.

FIG. 24 shows a lens cross-sectional view of the imaging optical system of the second embodiment. The imaging optical system according to the second embodiment includes a plano-convex lens L1 and a convex-plano lens L2. The plano-convex lens L1 is located on the image side, and the convex-plano lens L2 is located on the object side. The aperture stop S is arranged on the object side surface of the convex flat lens L2.

FIG. 25 shows a lens cross-sectional view of the imaging optical system of the third embodiment. The imaging optical system according to the third embodiment includes a plano-convex lens L1 and a plano-convex lens L2. The plano-convex lens L1 is located on the image side, and the convex-plano lens L2 is located on the object side. The aperture stop S is arranged on the object side surface of the convex flat lens L2.

FIG. 26 shows a lens cross-sectional view of the imaging optical system of the fourth embodiment. The imaging optical system according to the fourth embodiment includes a plano-convex lens L1 and a convex-plano lens L2. The plano-convex lens L1 is located on the image side, and the convex-plano lens L2 is located on the object side. The aperture stop S is arranged on the object side of the convex flat lens L2.

FIG. 27 shows a lens cross-sectional view of the imaging optical system of the fifth embodiment. The imaging optical system according to the fifth example includes a plano-convex lens L1 and a convex-plano lens L2. The plano-convex lens L1 is located on the image side, and the convex-plano lens L2 is located on the object side. The aperture stop S is arranged on the object side of the convex flat lens L2.

FIG. 28 shows a lens cross-sectional view of the imaging optical system of the sixth embodiment. The imaging optical system of the sixth embodiment includes a plano-convex lens L1 and a convex-plano lens L2. The plano-convex lens L1 is located on the image side, and the convex-plano lens L2 is located on the object side. The aperture stop S is arranged on the object side of the convex flat lens L2.

FIG. 29 shows a lens cross-sectional view of the imaging optical system of the seventh embodiment. The imaging optical system of the seventh embodiment includes a plano-convex lens L1 and a plano-convex lens L2. The plano-convex lens L1 is located on the image side, and the convex-plano lens L2 is located on the object side. The aperture stop S is arranged on the object side of the convex flat lens L2.

The convex lens L2 and the aperture stop S are filled with water. The space between the aperture stop S and the object plane is filled with a medium having a refractive index of 1.5163.

FIG. 30 shows a lens cross-sectional view of the imaging optical system of the eighth embodiment. The imaging optical system of Example 8 has a plano-convex lens L1 and a convex-plano lens L2. The plano-convex lens L1 is located on the image side, and the convex-plano lens L2 is located on the object side. The aperture stop S is arranged on the object side of the convex flat lens L2.

The convex lens L2 and the aperture stop S are filled with water. The space between the aperture stop S and the object plane is filled with a medium having a refractive index of 1.5163.

数 値 Numerical data of each of the above embodiments is shown below. In the surface data, r is the radius of curvature of each lens surface, d is the distance between each lens surface, nd is the refractive index of the d-line of each lens, and vd is the Abbe number of each lens. The stop is an aperture stop. Numerical data is data at the time of reverse tracking. In reverse tracing, light rays are traced from the image plane to the object plane.

各種 In various data, f is the focal length of the entire system, ω is a half angle of view, IH is the image height, and φap is the diameter of the stop. The image height IH represents the outer diameter of the annular image.

Numerical example 1
Unit: mm

Surface data surface number r d nd νd
Image plane ∞ 0.110
1 0.300 0.600 1.883 40.8
2 -0.300 0.000
3 (aperture) ∞ 1.135
Object plane ∞

Various data f 0.319
ω 36.5 °
φap 0.06
IH 0.36

Numerical example 2
Unit: mm

Surface data surface number r d nd νd
Image plane ∞ 0.070
1 ∞ 0.350 1.8830 40.8
2 -0.350 0.010
3 0.350 0.350 1.8830 40.8
4 ∞ 0.000
5 (aperture) ∞ 0.664
Object plane ∞

Various data f 0.200
ω 43.6 °
φap 0.06
IH 0.26

Numerical example 3
Unit: mm

Surface data surface number r d nd νd
Image plane ∞ 0.030
1 ∞ 0.300 1.8830 40.8
2 -0.400 0.010
3 0.200 0.200 1.8830 40.8
4 ∞ 0.000
5 (aperture) ∞ 0.580
Object plane ∞


Various data f 0.152
ω 63.3 °
φap 0.06
IH 0.30

Numerical example 4
Unit: mm

Surface data surface number r d nd νd
Image plane ∞ 0.070
1 ∞ 0.400 1.8830 40.8
2 -0.460 0.010
3 0.274 0.300 1.8830 40.8
4 ∞ 0.010
5 (aperture) ∞ 0.439
Object plane ∞

Various data f 0.196
ω 47.3 °
φap 0.06
IH 0.30

Numerical example 5
Unit: mm

Surface data surface number r d nd νd
Image plane ∞ 0.070
1 ∞ 0.400 1.8830 40.8
2 -0.376 0.010
3 0.227 0.200 1.8830 40.8
4 ∞ 0.010
5 (aperture) ∞ 0.648
Object plane ∞

Various data f 0.237
ω 32.4 °
φap 0.06
IH 0.30

Numerical example 6
Unit: mm

Surface data surface number r d nd νd
Image plane ∞ 0.070
1 ∞ 0.400 1.5163 64.1
2 -0.312 0.010
3 0.224 0.200 1.6516 58.6
4 ∞ 0.010
5 (aperture) ∞ 0.496
Object plane ∞

Various data f 0.221
ω 35.3 °
φap 0.06
IH 0.30

Numerical example 7
Unit: mm

Surface data surface number r d nd νd
Image plane ∞ 0.030
1 ∞ 0.250 1.8830 40.8
2 -0.350 0.010
3 0.160 0.200 1.8830 40.8
4 ∞ 0.010 1.3330 55.7
5 (aperture) ∞ 0.566 1.5163 64.1
Object plane ∞

Various data f 0.191 (in 1.5163)
ω 46.8 ° (in 1.5163)
φap 0.06
IH 0.30

Numerical example 8
Unit: mm

Surface data surface number r d nd νd
Image plane ∞ 0.030
1 ∞ 0.250 2.0033 28.3
2 -0.350 0.010
3 0.175 0.200 1.8830 40.8
4 ∞ 0.010 1.3330 55.7
5 (aperture) ∞ 0.772 1.5163 64.1
Object plane ∞

Various data f 0.194 (in 1.5163)
ω 45.4 ° (in 1.5163)
φap 0.06
IH 0.30

Next, the values of the conditional expressions in each embodiment are shown below.
Example 1 Example 2 Example 3 Example 4
(5) P '-3.14 -2.69 -3.53 -2.74

Example 5 Example 6 Example 7 Example 8
(5) P '-2.65 -2.86 -4.28 -4.12

FIGS. 31 to 38 show aberration diagrams of the respective embodiments. The aberration diagrams of each embodiment will be described. (A) shows spherical aberration (SA), (b) shows astigmatism (AS), and (c) shows distortion (DT).

Hereinafter, embodiments of the endoscope optical system will be described in detail with reference to the drawings. The present invention is not limited by the embodiment.

FIG. 39 shows a cross-sectional view of the endoscope optical system according to the first embodiment. The endoscope optical system 150 according to the first embodiment includes a distal end member 151 and an imaging optical system 154. The imaging optical system according to the first embodiment is used as the imaging optical system 154.

However, in the imaging optical system 154, the value of d0 is changed from 1.135 mm to 1.14 mm with respect to the imaging optical system of the first embodiment. d0 is the distance from the object plane to the aperture stop.

The tip member 151 has a tip optical system 152 and a holding frame 153. The tip optical system 152 has an outer peripheral surface 152a and an inner surface 152b. The outer peripheral surface 152a is a conical surface. The inner surface 152b is a flat surface.

FIG. 40 shows a cross-sectional view of the endoscope optical system according to the second embodiment. The endoscope optical system 160 according to the second embodiment includes a tip member 161 and an imaging optical system 164. The imaging optical system according to the first embodiment is used as the imaging optical system 164.

However, in the imaging optical system 164, the value of d0 is changed from 1.135 mm to 3.29 mm with respect to the imaging optical system of the first embodiment. Further, the value of d3 is changed from 0.11 mm to 0.05 mm. d3 is the distance from the most image side surface of the imaging optical system 154 to the image surface.

The tip member 161 has a tip optical system 162 and a holding frame 163. The tip optical system 162 has an outer peripheral surface 162a and an inner surface 162b. The outer peripheral surface 162a has a hemispherical surface, a conical surface, and a cylindrical surface. The inner surface 162b is a flat surface.

FIG. 41 is a cross-sectional view of the endoscope optical system according to the third embodiment. The endoscope optical system 170 according to the third embodiment includes a tip member 171 and an imaging optical system 174. The imaging optical system according to the first embodiment is used as the imaging optical system 174.

However, in the imaging optical system 174, the value of d0 is changed from 1.135 mm to 4.84 mm with respect to the imaging optical system of the first embodiment. Also, the value of d3 has been changed from 0.11 mm to 0.04 mm.

The tip member 171 has a tip optical system 172 and a holding frame 173. The tip optical system 172 has an outer peripheral surface 172a and an inner surface 172b. The outer peripheral surface 172a has a hemispherical surface, a conical surface, and a cylindrical surface. The inner surface 172b is a flat surface.

FIG. 42 is a cross-sectional view of the endoscope optical system according to the fourth embodiment. The endoscope optical system 180 according to the fourth embodiment includes a distal end member 181 and an imaging optical system 184. The imaging optical system according to the second embodiment is used as the imaging optical system 184.

The tip member 181 has a tip optical system 182 and a holding frame 183. The tip optical system 182 has an outer peripheral surface 182a and an inner surface 182b. The outer peripheral surface 182a is a conical surface. The inner surface 182b is a flat surface.

FIG. 43 shows a sectional view of the endoscope optical system of the fifth embodiment. The endoscope optical system 190 according to the fifth embodiment includes a distal end member 191 and an imaging optical system 194. The imaging optical system according to the third embodiment is used as the imaging optical system 194.

The tip member 191 has a tip optical system 192 and a holding frame 193. The tip optical system 192 has an outer peripheral surface 192a and an inner surface 192b. The outer peripheral surface 192a is a conical surface. The inner surface 192b is a flat surface.

FIG. 44 shows a cross-sectional view of the endoscope optical system of the sixth embodiment. The endoscope optical system 200 according to the sixth embodiment includes a distal end member 201 and an imaging optical system 204. The imaging optical system according to the fourth embodiment is used as the imaging optical system 204.

The tip member 201 has a tip optical system 202 and a holding frame 203. The tip optical system 202 has an outer peripheral surface 202a and an inner surface 202b. The outer peripheral surface 202a has a conical surface and a cylindrical surface. The inner surface 202b has a curved surface, a frustoconical side surface, and a flat surface. The curved surface is a part of the spherical surface.

FIG. 45 is a cross-sectional view of the endoscope optical system according to the seventh embodiment. The endoscope optical system 210 according to the seventh embodiment includes a distal end member 211 and an imaging optical system 214. The imaging optical system according to the fifth embodiment is used as the imaging optical system 214.

The tip member 211 has a tip optical system 212 and a holding frame 213. The tip optical system 212 has an outer peripheral surface 212a and an inner surface 212b. The outer peripheral surface 212a has a conical surface and a cylindrical surface. The inner surface 212b has a curved surface, a cylindrical surface, and a flat surface. The curved surface is a part of the ellipsoid.

FIG. 46 shows a cross-sectional view of the endoscope optical system of the eighth embodiment. The endoscope optical system 220 according to the eighth embodiment includes a distal end member 221 and an imaging optical system 224. The imaging optical system of Example 6 is used as the imaging optical system 224.

The tip member 221 has a tip optical system 222 and a holding frame 223. The tip optical system 222 has an outer peripheral surface 222a and an inner surface 222b. The outer peripheral surface 222a has a conical surface and a cylindrical surface. The inner surface 222b has a curved surface, a frustoconical side surface, and a flat surface. The curved surface is a part of the ellipsoid.

FIG. 47 shows a sectional view of the endoscope optical system of the ninth embodiment. The endoscope optical system 230 according to the ninth embodiment includes a tip member 231 and an imaging optical system 234. The imaging optical system 234 has two lenses.

The tip member 231 has a tip optical system 232 and a holding frame 233. The tip optical system 232 has an outer peripheral surface 232a and an inner surface 232b. The outer peripheral surface 232a is a conical surface. The inner surface 232b has a curved surface, a cylindrical surface, and a flat surface.

In the tip optical system 232, a lens is formed by the curved surface and the cylindrical surface. In the endoscope optical system 230, a part of the lens of the imaging optical system 234 is formed integrally with the tip optical system 232.

FIG. 48 is a sectional view of the endoscope optical system according to the tenth embodiment. The endoscope optical system 240 according to the tenth embodiment includes a tip member 241 and an imaging optical system 244. The imaging optical system according to the fourth embodiment is used as the imaging optical system 244.

The tip member 241 has a tip optical system 242 and a holding frame 243. The tip optical system 242 has an outer peripheral surface 242a and an inner surface 242b. The outer peripheral surface 242a has a conical surface and a cylindrical surface. The inner surface 242b has a curved surface, a frustoconical side surface, and a flat surface. The curved surface is a part of the spherical surface. The curved surface is provided at a position facing the imaging optical system 244 and at a position facing the illumination unit.

FIG. 49 shows a sectional view of the endoscope optical system of the eleventh embodiment. The endoscope optical system 250 according to the eleventh embodiment includes a tip member 251 and an imaging optical system 254. The imaging optical system according to the seventh embodiment is used as the imaging optical system 254.

The tip member 251 has a tip optical system 252 and a holding frame 253. The tip optical system 252 has an outer peripheral surface 252a and an inner surface 252b. The outer peripheral surface 252a is a conical surface. The inner surface 252b is a flat surface.

の 間 The space between the inner surface 252b and the imaging optical system 254 is filled with water. Thereby, in the endoscope optical system 250, an angle of view of 90 ° or more is ensured in the distal end optical system 252.

The object is illuminated with the light emitted from the illumination unit 255. The illumination unit 255 has an LED.

FIG. 50 is a sectional view of the endoscope optical system according to the twelfth embodiment. The endoscope optical system 260 according to the twelfth embodiment includes a tip member 261 and an imaging optical system 264. The imaging optical system of Example 8 is used for the imaging optical system 264.

The tip member 261 has a tip optical system 262 and a holding frame 263. The tip optical system 262 has an outer peripheral surface 262a and an inner surface 262b. The outer peripheral surface 262a has a conical surface and a cylindrical surface. The inner surface 262b is a flat surface.

の 間 The space between the inner surface 262b and the imaging optical system 264 is filled with water. Thereby, in the endoscope optical system 260, an angle of view of 90 ° or more is ensured in the distal end optical system 262.

Next, the values of the conditional expressions in each embodiment are shown below. -(Hyphen) indicates that there is no corresponding configuration.
Example 1 Example 2 Example 3 Example 4
(1) N 1.51633 1.51633 1.51633 1.51633
(2) L / d 1 1 1 1
(3) θ-20 10-
(3 ') θ 60--65
(3 ”) θ----
(4) C 0 0 0 0
(6) L / D 0.87--0.77
(6 ') L / D-2.75 4.83-

Example 5 Example 6 Example 7 Example 8
(1) N 1.51633 1.51633 1.51633 1.51633
(2) L / d 1 1.21 1.54 1.39
(3) θ----
(3 ') θ 65 65 60 60
(3 ”) θ----
(4) C 0 140.84 2.44 3.23
(6) L / D 0.79 1.16 1.36 1.25
(6 ') L / D----

Example 9 Example 10 Example 11 Example 12
(1) N 1.51633 1.51633 1.51633 1.51633
(2) L / d 0.86 1.21 1 1
(3) θ----
(3 ') θ 65 65 60-
(3 ”) θ---140
(4) C--0 0
(6) L / D 0.79 1.16 0.86 0.57
(6 ') L / D----

The parameter values of each embodiment are shown below. φ is the inner diameter of the tip optical system.
Example 1 Example 2 Example 3 Example 4
L 1.30 4.13 7.25 1.16
d 1.30 4.13 7.25 1.16
D 1.50 1.50 1.50 1.50
φ 1 1 1 1

Example 5 Example 6 Example 7 Example 8
L 1.18 1.39 1.63 1.50
d 1.18 1.15 1.06 1.08
D 1.50 1.20 1.20 1.20
φ 1

Example 9 Example 10 Example 11 Example 12
L 1.18 1.39 0.60 0.63
d 1.38 1.15 0.60 0.63
D 1.50 1.20 0.70 1.10

The endoscope according to the present embodiment includes the endoscope optical system according to the present embodiment, an imaging element, an illumination unit, and an insertion unit having a holding member, and the imaging optical system and the illumination unit , And arranged inside the holding member.

FIG. 51 is a diagram showing an insertion portion of the endoscope. The insertion section 270 has an endoscope optical system, an illumination section, and the holding member 11. The endoscope optical system has a tip member 271 and a parallel flat plate 5. The imaging optical system and the illumination unit are disposed inside the holding member 11. In FIG. 51, the imaging optical system and the illumination unit are not shown.

鉗 A forceps hole 272 is provided in the insertion section shown in FIG. Therefore, the endoscope optical system is arranged at a position away from the central axis of the insertion section.

In the endoscope of the present embodiment, flare is likely to occur due to the illumination light reflected on the outer peripheral surface. However, since the endoscope according to the present embodiment includes the above-described endoscope optical system, the occurrence of flare can be suppressed.

Therefore, with the endoscope of the present embodiment, an object located near the outer peripheral surface of the distal end optical system or an object in contact with the outer peripheral surface of the distal end optical system can be clearly observed.

In the above description, the imaging optical system is treated as an optical system for forming an optical image of an object. However, the imaging optical system can be used as a scanning optical system that scans illumination light.

In FIG. 51, for example, the imaging optical system 3 shown in FIG. 1 can be used as an imaging optical system (not shown). As shown in FIG. 19, light from one point on the object plane OB is condensed on one point on the image plane I. This means that, when the light source is arranged at one point on the image plane I, the light emitted from the light source is collected at one point on the object plane OB.

Therefore, for example, a point light source is arranged at the position of the image plane I. In this way, one point on the object plane OB can be illuminated. Further, by receiving light from one illuminated point, it is possible to acquire information on one point on the object plane OB. The light from the object plane OB may be provided, for example, by arranging a light receiving element at the location of the illumination unit.

Furthermore, by moving the point light source, information on the entire object plane OB can be obtained. The point light source may be moved, for example, by moving the end of one optical fiber in the plane of the image plane I. The movement of the end of the optical fiber can be realized, for example, by disposing an actuator near the end of the optical fiber. The movement trajectory of the optical fiber can be, for example, spiral.

The light source arranged at the position of the image plane I may be any light source as long as it can be regarded as a point light source. If the size of the light emitting surface of the optical fiber is large enough to be regarded as a point light source, the light emitting surface can also be called a point light source. For example, a single mode fiber can be used as the optical fiber.

光 The light exit surface of the fiber bundle may be arranged at the position of the image plane. In the fiber bundle, a plurality of optical fibers are bundled into one. By changing the optical fiber on which the illumination light is incident, the movement of the point light source can be realized without moving the optical fiber.

In the endoscope of the present embodiment, the distal end of the insertion portion has a connection portion, the distal end member has a connection portion, and the distal end member can be attached to and detached from the insertion portion via the two connection portions. preferable.

According to the endoscope of the present embodiment, a clear image can be obtained in the side viewing direction at the time of observation, even though the diameter of the insertion portion is small.

(4) Since the connection portion is provided in each of the distal end member and the insertion portion of the endoscope, the distal end member can be attached to and detached from the insertion portion. At one end of the tip member, a tip optical system is located. Therefore, the tip optical system can also be attached to and detached from the insertion section. Thus, according to the endoscope of the present embodiment, the tip member can be replaced.

先端 As described above, the distal end member may have the distal end optical system and the holding frame. The tip optical system and the holding frame may be separable. In this case, for the holding frame and the tip optical system, for example, the shape, size, thickness, or material can be variously changed. Therefore, a plurality of tip members having different specifications can be prepared. By doing so, observation can be performed with the tip member suitable for observation.

In the endoscope of the present embodiment, it is preferable that the distal end optical system is always fixed to the distal end of the insertion section.

According to the endoscope of the present embodiment, a clear image can be obtained in the side viewing direction at the time of observation, even though the diameter of the insertion portion is small.

高 い Further, since the distal end member is always fixed to the distal end of the insertion portion, high airtightness can be maintained. Therefore, according to the endoscope of the present embodiment, the imaging optical system can be protected from dirt and the like.

内 The endoscope system according to the present embodiment includes the endoscope described above, an image processing device, and a light source device.

FIG. 52 is a diagram showing an example of an endoscope and an example of an endoscope system. FIG. 52A is a diagram illustrating a rigid endoscope, and FIG. 52B is a diagram illustrating a flexible endoscope system.

よ う As shown in FIG. 52 (a), an endoscope optical system 281 is arranged at the distal end of the insertion section of the endoscope 280. The endoscope optical system of the present embodiment can be used as the endoscope optical system 281. Further, the insertion section has an image sensor. Thus, an image in the side viewing direction can be obtained in all directions. Therefore, various parts can be imaged from an angle different from that of a conventional endoscope.

Further, as shown in FIG. 52 (b), an endoscope optical system 291 is arranged at the distal end of the insertion section of the endoscope 290. The endoscope optical system of the present embodiment can be used as the endoscope optical system 291. Further, the insertion section has an image sensor. Thus, an image in the side viewing direction can be obtained in all directions. Therefore, various parts can be imaged from an angle different from that of a conventional endoscope.

The acquired image can be displayed on the display device 293 via the image processing device 292. The image processing device 292 can perform various image processing.

で は In the endoscope optical system 281 and the endoscope optical system 281, the distal end member may be replaceable with respect to the insertion portion, or may be constantly fixed to the insertion portion.

場合 When the tip member is detachable from the insertion portion, the tip member can be replaced. For example, if a plurality of tip members having different optical specifications are prepared, observation can be performed with a tip member suitable for observation.

As described above, the present invention provides a distal member capable of clearly observing an object located near the outer peripheral surface of the distal optical system or an object in contact with the outer peripheral surface of the distal optical system. Suitable for mirror optics, endoscopes, and endoscope systems.

Reference Signs List 1 endoscope optical system 2 tip member 3 imaging optical system 4 tip optical system 4a outer peripheral surface 4b inner surface 5 parallel plate 6 holding member 10, 20 insertion part 11 holding member 12, 21 illumination unit 30, 40, 50, 55, 70 Endoscope optical system 31, 41, 51, 56, 60, 71 Tip member 32, 43, 52, 57, 61, 72 Tip optical system 32a, 43a, 52a, 57a, 61a, 72a Outer peripheral surface 32b, 43b, 53b, 57b, 61b, 72b Inner surface 32b1, 43b1, 61b1, 72b1 First inner surface 32b2, 43b2, 61b2, 72b2 Second inner surface 32b3, 43b3, 61b3, 72b3 Third inner surface 42 Imaging optical system 42a, 42b Lens 58 Cone 62 Holding frame 63 Spherical surface 73 Liquid 80, 90, 100, 110, 120, 130 Tip member 81, 91, 101 , 111, 131 tip optical systems 82, 102, 112, 121, holding frame 81a, 91a, 101a, 111a, 131a outer peripheral surface 81a1, 91a1, 101a1, 131a1 first outer peripheral surface 81a2, 91a2, 101a2, 131a2 second outer peripheral surface 81b, 91b, 101b, 111b, 131b Inner surface 82a, 102a, 112a, 121a, Outer surface 82b, 102b, 112b, 121b, Inner surface 132 Metal film
140 endoscope optical system 141 distal end member 142 distal end optical system 142a outer peripheral surface 142b inner surface 142b1 first inner surface 142b2 second inner surface 142b3 third inner surface 143 holding frame 144 imaging optical system 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, endoscope optical system 151, 161, 171, 181, 191, 201, 211, 221, 231, 241, 251, 261, tip member 152, 162, 172, 182 , 192, 202, 212, 222, 232, 242, 252, 262, tip optical systems 152a, 162a, 172a, 182a, 192a, 202a, 212a, 222a, 232a, 242a, 252a, 262a, outer peripheral surfaces 152b, 162b, 172b, 182b, 192b , 202b, 212b, 222b, 232b, 242b, 252b, 262b, inner surfaces 153, 163, 173, 183, 193, 203, 213, 223, 233, 243, 253, 263, holding frames 154, 164, 174, 184, 194, 204, 214, 224, 234, 244, 254, 264, imaging optical system 255 illumination unit 270 insertion unit 271 tip member 272 forceps hole 280 endoscope 281 endoscope optical system 290 endoscope 291 endoscope Optical system 292 Image processing device 293 Display device AX, AXo Optical axis PE One end of outer peripheral surface PE 'The other end of outer peripheral surface P1 First intersection point P2 Second intersection point P3 Position of paraxial curvature center PL Predetermined line Δ Predetermined Spacing OB Object plane I Image plane θ Conical apex angle Lam, Lbm, Lcm, Lam ′, Lbm ′, Luminous flux Lcm ′ Merge Light beam Lbs in null section, the virtual image L1, L2 lens S aperture stop in the virtual image Isagi sagittal section in the light beam Imeri meridional section in Lbs' sagittal section

Claims (19)

A tip member connected to the holding member,
The tip member has a tip optical system,
The tip optical system has an inner surface and an outer peripheral surface,
One end of the outer peripheral surface is located on the optical axis of the tip optical system,
The inner surface is located closer to the holding member than one end of the outer peripheral surface,
The inner surface has a first region in contact with an end surface of the holding member,
The space between the inner surface and the outer peripheral surface is filled with a transparent substance having a refractive index greater than 1.
A tip member satisfying the following conditional expressions (1) and (2).
1.3 <N <1.6 (1)
0.4 <L / d <1.5 (2)
here,
N is the refractive index of the transparent substance at d-line,
L is the distance from the one end to the first intersection;
d is the distance from the one end to the second intersection;
The first intersection is an intersection between a predetermined line and the optical axis;
The predetermined line is in contact with the other end of the outer peripheral surface, and a straight line orthogonal to the optical axis;
The second intersection is an intersection between the inner surface and the optical axis,
It is. The tip member according to claim 1, wherein the outer peripheral surface is a surface including a side surface of a truncated cone. The tip member according to claim 2, wherein the truncated cone is a part of a cone satisfying the following conditional expression (3).
0 ° <θ <40 ° (3)
Where θ is the apex angle of the cone,
It is. The tip member according to claim 2, wherein the truncated cone is a part of a cone satisfying the following conditional expression (3 ').
60 ° <θ <70 ° (3 ')
Where θ is the apex angle of the cone,
It is. The tip member according to claim 2, wherein the truncated cone is a part of a cone satisfying the following conditional expression (3 ").
110 ° <θ <180 ° (3 ”)
Where θ is the apex angle of the cone,
It is. The inner surface has the first region and a second region including the optical axis,
The second area includes a predetermined surface,
The predetermined surface is located closer to one end of the outer peripheral surface than the first region,
The tip member according to claim 1, wherein the following conditional expression (4) is satisfied.
0 (1 / mm) ≦ C <5 (1 / mm) (4)
here,
C is the reciprocal of the predetermined interval,
The predetermined interval is an interval between the paraxial center of curvature of the predetermined surface and the first intersection;
It is. The tip member according to claim 1, wherein the following conditional expression (5) is satisfied.
0 <L / D <1.5 (5)
here,
L is a distance from the one end to the first intersection;
D is the outer diameter of the tip optical system,
The first intersection is an intersection between the predetermined line and the optical axis,
The predetermined line is in contact with the other end of the outer peripheral surface, and a straight line orthogonal to the optical axis;
It is. The tip member according to claim 1, wherein the following conditional expression (5 ') is satisfied.
1.5 <L / D <10 (5 ′)
here,
L is a distance from the one end to the first intersection;
D is the outer diameter of the tip optical system,
The first intersection is an intersection between the predetermined line and the optical axis,
The predetermined line is in contact with the other end region of the outer peripheral surface, and is a straight line orthogonal to the optical axis;
It is. Has a holding frame,
The tip member according to claim 1, wherein the holding frame is located at the other end of the outer peripheral surface. A tip member according to any one of claims 1 to 9,
An endoscope optical system, comprising: an imaging optical system arranged on the holding member. The first region is a region formed by a plane,
An end face of the holding member in contact with the first region is a flat surface,
The endoscope optical system according to claim 10, wherein the two planes are planes orthogonal to an optical axis of the tip optical system. The inner surface has the first region and a second region including the optical axis,
The second area includes a predetermined surface,
The predetermined surface is located closer to one end of the outer peripheral surface than the first region,
The endoscope optical system according to claim 10, wherein a refractive index difference suppression unit is provided between the predetermined surface and the imaging optical system. 13. The endoscope optical system according to claim 12, wherein the refractive index difference suppressing section is filled with a liquid having a refractive index of 1.3 or more. The imaging optical system includes only a transmission surface and has a field curvature aberration,
The endoscope optical system according to claim 10, wherein the following conditional expression (6) is satisfied.
-10 <P '<-0.8 (6)
Here, P ′ is a Petzval sum and is represented by the following equation:

r _i is the radius of curvature of the i-th transmission surface,
n ′ _i is the refractive index on the exit side of the i-th transmission surface,
_ni is the refractive index on the incident side of the i-th transmission surface;
n ′ is the refractive index of the image space,
i is the number of the transmission surface,
k is the total number of transmission surfaces,
It is. The inner surface has the first region and a second region including the optical axis,
The endoscope optical system according to claim 10, wherein the second region has a curved surface with a concave surface facing the imaging optical system. An endoscope optical system according to any one of claims 10 to 15, and an image sensor,
Lighting part,
An insertion portion having the holding member,
The endoscope, wherein the imaging optical system and the illumination unit are arranged inside the holding member. The distal end of the insertion portion has a connection portion,
The tip member has a connection portion,
The endoscope according to claim 16, wherein the distal end member is attached to and detached from the insertion portion via the two connection portions. 17. The endoscope according to claim 16, wherein the distal end optical system is always fixed to a distal end of the insertion section. An endoscope according to any one of claims 16 to 18,
An image processing device;
An endoscope system comprising: a light source device.

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