JPH07248454A - Hard endoscope - Google Patents

Abstract

PURPOSE:To reduce the cost of a hard endoscope and to make the inserting part thereof disposable by constituting the hard endoscope of the inserting part and an eyepiece part of a television photographing device and constituting an optical system in the inserting part of a small number of optical elements. CONSTITUTION:This hard endoscope is constituted of the inserting part 1 inserted to an observing part and the eyepiece part 2 connected to the near end part on the side opposite to the side inserted with the inserting part 1 or the television photographing device provided with a photographing element or the like inside. Then, the primary formed image of an object is formed by an objective optical system 5 arranged in the inserting part 1 and light from the primary formed image is made parallel luminous flux by an eyepiece optical system arranged in the eyepiece part 2 or the image of the light is formed on an image pickup means by an image forming optical system in the television photographing device. Besides, the inserting part 1 and the eyepiece part 2 or the television photographing device are fitted in attachable and detachable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rigid endoscope (rigid endoscope) widely used in the medical field, and mainly to an inexpensive disposable rigid endoscope optical system.

[0002]

2. Description of the Related Art In recent years, a minimally invasive procedure using an endoscope and a dedicated treatment instrument has become widespread in the field of medical surgery. Conventionally, it becomes possible to treat diseases that require laparotomy with minimally invasiveness under the endoscope, and the social burden on the patient can be reduced by shortening the hospital stay, etc. Surgery is expected to continue developing.

An endoscope is divided into a flexible endoscope and a rigid endoscope depending on the structure of the insertion portion. Among them, a rigid endoscope having excellent image quality is used for endoscopic surgery.
Furthermore, since it can be autoclaved (steam sterilization), it has the advantage of using a rigid endoscope.

In recent years, nosocomial infections have become a serious problem, and sterilization of medical equipment is extremely important. Autoclave devices have become more widespread than other sterilization devices, and endoscopes have a structure that can be autoclaved. I need to.

Since the rigid endoscope does not have a soft portion, it is easy to obtain autoclave resistance in terms of material selection and structure. Therefore, a rigid endoscope having autoclave resistance is usually sterilized for each case, reused, and repeatedly used.

On the other hand, attempts have been made to dispose of the rigid endoscope itself in order to prevent hospital infection due to the rigid endoscope. In order to make such a disposable rigid endoscope, it is important to reduce the cost while ensuring the practicality.

FIG. 13 shows an observation optical system of a conventional rigid endoscope. In this conventional rigid endoscope, an objective optical system 12, a relay optical system 13, and an eyepiece optical system 14 are integrally housed in a main body 11. This conventional rigid endoscope transmits an object image by normally relaying the image of the object formed by the objective optical system 12 about three times by the relay optical system 13 and observing it through the eyepiece optical system 8. Has become.

[0008]

If the rigid endoscope as shown in FIG. 13 is to be disposable, the number of lenses in the disposable portion is too large, which causes a cost problem.

It is an object of the present invention to provide a rigid-mirror optical system in which the number of disposable lenses is extremely reduced and the increase in cost due to the disposable is extremely reduced.

[0010]

The rigid endoscope of the present invention comprises:
An insertion part that has a distal end (the end farthest from the observer) and a proximal end (the end closest to the observer), and inserts the distal end side into the observation site, and the proximal part of the insertion part. An eyepiece connected to the end, and an objective optical system is included in the insertion portion. The eyepiece directly receives the light from the primary imaging formed by the objective optical system and An optical system for emitting a parallel light beam is arranged, and the insertion part and the eyepiece part are detachable. Since the insertion portion and the eyepiece portion of the rigid endoscope of the present invention are attachable and detachable, the insertion portion that is contaminated by use can be removed from the eyepiece portion and disposed of.
Here, since only the objective optical system is housed in the insertion section, the number of lenses is extremely small, and the insertion section, that is, the disposable section can be constructed at low cost.

The rigid endoscope of the present invention has a structure as shown in FIG. 1, for example. In the figure, reference numeral 1 denotes a cylindrical insertion portion having a distal end 1a and a proximal end 1b, inside which an objective optical system 5 is arranged. Reference numeral 2 denotes an eyepiece portion that is detachably attached to the proximal end 1b of the insertion portion 1, and an eyepiece optical system 6 is provided inside. The plate-shaped members arranged before and after the eyepiece optical system 6 are cover glasses. This rigid endoscope is inserted into an observation site (not shown) such as the inside of a body cavity from the side of the distal end 1a of the insertion portion to observe an object. That is, the image of the object to be observed is formed by the objective optical system 5 in the vicinity of the proximal end 1b of the insertion portion (image I ₁ ). The light from this image enters the eyepiece optical system 6 attached to the proximal end of the insertion portion directly, that is, without passing through the relay optical system, and is recombined inside the eyepiece optical system by the front lens of the eyepiece optical system. It is imaged (Image I ₂ ). The light from the image I ₂ becomes a substantially parallel luminous flux and exits the eyepiece optical system 6, and the observer can see the image of the object by receiving this light.

FIG. 2 is a diagram showing the configuration of another example of the present invention. This example is for television shooting, and the configuration of the insertion section 1 is the same as that of FIG. 1, but instead of the eyepiece section 2, a television camera adapter 3 and a television camera 4 can be attached. The TV camera adapter 3 has an imaging optical system 7 inside, and the TV camera 4 has an imaging means such as a fixed imaging device inside. An image of the object is formed by the objective optical system 5 in the vicinity of the proximal end 1b of the insertion portion 1 (image I ₁ ). The light from this image enters the image forming optical system 7 of the TV camera adapter 3 directly, that is, without passing through the relay optical system, and the image of the object is re-imaged on the solid-state image sensor provided in the TV camera 4. To be done. This image is observed through display means such as a monitor TV. The TV camera adapter 3 and the TV camera 4 can also be attached to and detached from each other.

In these rigid endoscopes, the insertion portion 1 and the eyepiece portion 2 or the television camera adapter 3 can be attached and detached,
After being used for observation, the contaminated insert 1 can be removed from the eyepiece 2 and discarded. Also, the eyepiece 2, the adapter, and the television camera can be reused by attaching a new insertion part.

Incidentally, in these, as shown in FIG. 3, a sterilization cover 8 may be used to cover a portion other than the insertion portion 1, that is, a television camera adapter, a television camera, an eyepiece portion or the like. In FIG. 3, one end of the sterilization cover 8 is integrated with the insertion portion 1. Alternatively, the insertion portion 1 may be elastically fitted into the insertion portion 1, or the insertion portion 1 may be fixed by an appropriate fixing means.
It may be fixed to. The other end of the cover 8 has a large opening.

When the sterilization cover 8 is integrated with the insertion portion 1, the eyepiece portion can be removed by inserting the eyepiece portion or the like from the opening at the other end of the cover 8 and connecting it to the insertion portion 1. It is in a state of being covered with the sterilization cover 8. When the sterilization cover 8 and the insertion part 1 are separate bodies, the insertion part 1 and the eyepiece part are connected,
The sterilization cover 8 is put on the eyepiece or the like from the distal end of the insertion portion 1. As a result, the eyepiece and the like can be kept even cleaner. In FIG. 3, reference numeral 2 denotes the eyepiece portion shown in FIG. 1, but reference numeral 15 denotes a TV photographing adapter which can be attached to and detached from the eyepiece portion 2, and which is substantially parallel to the inside and which is emitted from the eyepiece optical system. An image forming optical system for forming an image of the light flux is arranged. The TV camera 4 is the same as that shown in FIG.

Next, each optical system used in the rigid endoscope of the present invention will be described in detail.

First, the objective optical system will be described. The objective optical system used in the rigid endoscope of the present invention is a very long optical system that extends substantially over the entire length of the insertion portion. Therefore, a conventional objective optical system for a rigid endoscope (an objective optical system for a rigid endoscope using a relay optical system for transmitting an image) is used. ) And the configuration is very different.

The objective optical system of the present invention has a first lens group having a negative power, which is arranged near the distal end 1a of the insertion portion 1, and a positive power which is arranged at an intermediate portion of the insertion portion 1. It is composed of a second lens group.

As shown in FIG. 4 (A), a virtual image I'of the object reduced to about the outer diameter of the lens or less is formed near the distal end 1a of the insertion portion 1 by the first lens group, and The virtual image I ′ is imaged by the second lens group to form a primary image I ₁ near the proximal end 1b of the insertion portion 1. When the aperture stop is not arranged in the optical system, the edge (side surface) of the lens of the second lens group or a part of the lens holding frame serves as the aperture stop. As shown in FIG. 4A, if the first lens unit is not arranged near the distal end 1a and has a negative power, the off-axis light beam cannot pass through the pipe, which is not preferable. If the second lens group does not have a positive power, image formation becomes difficult,
If this second lens group is not located at the intermediate portion of the insertion portion 1, off-axis light flux is eclipsed or NA is lowered, resulting in reduced brightness, which is not preferable.

It is desirable that the second lens group satisfy the following condition (1). (1) 0.7 <| β ₂ | <1.5 where β ₂ is the magnification of the second lens group when observing an object point at infinity.

Under the condition (1), if | β ₂ | is 0.7 or less, the luminous flux obtained on the object side becomes narrow and the brightness is lowered, which is not preferable. If | β ₂ | is 1.5 or more, off-axis light flux is eclipsed in the vicinity of the proximal end and the image is eclipsed, which is not preferable.

The position of the primary image formation of the objective optical system is preferably near the proximal end 1b of the insertion section 1. Therefore, it is preferable to satisfy the following condition (2). (2) 0.7 <L _i / L _e <1.5 where L _i is the distance from the first surface of the objective optical system to the primary image formation, and L _e is the effective length of the insertion portion. Here, the effective length of the insertion portion means the length of a portion having a small outer diameter to be inserted into the trailer curl or the sheath.

Under the above condition (2), when the value of L _i / L _e becomes 0.7 or less, the primary image formation I ₁ goes into the pipe of the insertion section 1, and as shown in FIG. The off-axis light beam is eclipsed by. Further, when the value of L _i / L _e is 1.5 or more, the luminous flux obtained on the object side becomes narrow and the NA becomes small, so that the brightness decreases.

In the objective optical system of the present invention, it is preferable that the first lens group and the second lens group have a simple structure with a small number of lenses in order to keep the cost of the insertion portion low. Therefore, it is preferable that the first lens group is a negative single lens having a concave surface on the image side in order to suppress off-axis aberrations. It is even more preferable that the object-side surface of this negative single lens is a flat surface. The second lens group is preferably a positive single lens or a positive cemented lens. The lens material may be glass or plastic.

FIG. 12 shows an example in which a perspective field conversion prism is arranged at the tip of the objective optical system of the rigid scope of the present invention, and one prism as shown is used. Usually, the field-of-view conversion prism uses two or more prisms, which is costly. 12
Since such a prism P is arranged after the first lens unit L ₁ and can be constituted by only one prism, the cost is low and it is particularly preferable when the insertion portion including this prism and the objective optical system is disposable.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rigid endoscope according to the present invention is shown in FIGS.
One of the features is that the objective optical system arranged in the insertion section 1 has a simple configuration as described above in order to make the insertion section 1 separable from the others so as to be disposable. . Each embodiment of the optical system of the present invention including this objective optical system will be described below.

The first embodiment of the optical system used in the rigid endoscope of the present invention has a construction as shown in FIG. 5 and has the following data. First Example Object distance = -30 (observation diopter = ^-1 m ^-1 ), incident NA = 0.0032 angle of view = 60.2 ° (image height = 125) r ₁ = ∞ d ₁ = 0.8000 n ₁ = 1.80610 ν ₁ = 40.95 r ₂ = 5.1410 d ₂ = 167.5000 r ₃ = 87.8610 d ₃ = 2.0000 n ₂ = 1.51633 ν ₂ = 64.15 r ₄ = ∞ (aperture) d ₄ = 2.0000 n ₃ = 1.51633 ν ₃ = 64.15 r ₅ = -87.8610 d _{5 = 167.6300 r 6 = ∞ d} 6 = 30.0000 r 7 = 24.6552 d 7 = 3.0000 n 4 = 1.69680 ν 4 = 55.52 r 8 = -17.2217 d 8 = 1.0000 n 5 = 1.69895 ν 5 = 30.12 r 9 = -560.9511 d _{9 = 40.4125 r 10 = 8.8507 d} 10 = 3.0000 n 6 = 1.51633 ν 6 = 64.15 r 11 = -5.2344 d 11 = 1.0000 n 7 = 1.71736 ν 7 = 29.51 r 12 = 59.7461 d 12 = 1.0000 r 13 = 8.8507 d 13 = 3.0000 n ₈ = 1.51633 ν ₈ = 64.15 r ₁₄ = -5.2344 d ₁₄ = 1.0000 n ₉ = 1.71736 ν ₉ = 29.51 r ₁₅ = 59.7461 d ₁₅ = 15.5875 r ₁₆ = 23.5293 d ₁₆ = 3.0000 n ₁₀ = 1.51633 ν ₁₀ = 64.15 r ₁₇ = -24 _{.0097 d 17 = 8.0000 r 18 =} ∞ d 18 = 16.2546 r 19 = 21.2180 d 19 = 0.9000 n 11 = 1.78472 ν 11 = 25.71 r 20 = 8.1750 d 20 = 2.6000 n 12 = 1.66672 ν 12 = 48.32 r 21 = - 18.7960 β ₂ = -0.958, L _i = 339.6, L _e = 300, L _i / L _e = 1.132, where r ₁ , r ₂ , ... Are the radius of curvature of each lens surface, d
₁ , d ₂ , ... Is the thickness of each lens and the lens interval, n
₁ , n ₂ , ... Is the refractive index of each lens, ν ₁ , ν ₂ ,.
Is the Abbe number of each lens.

In the above data, r _{1 to} r ₅ are objective optical systems, r _{7 to} r ₂₁ are eyepiece optical systems, r ₄ = ∞ is a virtual diaphragm, r ₆ = ∞ is a primary image formation, and r ₁₈ = ∞ is the secondary image formation.

In the first embodiment, the objective optical system is arranged on the insertion side and the eyepiece optical system is arranged on the eyepiece side with the primary image formation (r ₆ ) as a boundary. In this embodiment, since the relay optical system is not used, the number of lenses is greatly reduced by that amount, only the objective optical system exists in the insertion portion, and the number of lenses is extremely small. Further, the aberrations of the optical system including the objective optical system and the eyepiece optical system of the first embodiment are as shown in FIG. 9 and are well corrected. In FIG. 9, the horizontal axis of spherical aberration, astigmatism, and coma is represented by diopter.

FIG. 6 shows a second embodiment of the optical system used in the present invention. This second embodiment is used for the rigid endoscope of the present invention of the type shown in FIG. The rigid endoscope shown in FIG. 2 is used by connecting the TV camera adapter 3 to the insertion portion 1 and further connecting the TV camera 4 as described above. Is a disposable item. The television camera adapter and the television camera may be integrated into a television camera having an imaging optical system, and the insertion portion 1 may be detachably attached to the television camera, and the insertion portion may be separated from the camera after use and may be disposable. In these first and second embodiments,
The objective optical system is composed of a first lens group of a plano-concave single lens and a second lens group of a biconvex single lens, and multi-component glass is assumed as the material of these lenses. Further, since the biconvex lens of the second lens group is a symmetrical lens having the same radius of curvature on both surfaces, it is not necessary to distinguish between the front and the back during assembly. However, since the second lens group has a magnification close to unity and corresponds to an aperture stop, even if an asymmetrical lens, such as a plano-convex lens, is arranged with its front and back reversed, variation in aberration does not pose a problem. Therefore, even if the second lens group has an asymmetrical shape, it may be assembled without worrying about the orientation.

In these embodiments, the plano-concave lens of the first lens group is made of glass having a high refractive index and medium dispersion, and the plano-convex lens of the second lens group is made of glass having a low refractive index and low dispersion. That is, the refractive index and Abbe number of the first lens group are n ₁ and ν ₁ ,
When the refractive index and the Abbe number of the lens group are n ₂ and ν ₂ , the following condition (3) is satisfied. (3) n ₁ > n ₂ , ν ₁ <ν _{2 For} the first lens group, glass with a high refractive index is suitable for weakening the curvature of the concave surface, and dispersion is not too large to suppress chromatic aberration of magnification. Glass is suitable. The second lens group need not have a low refractive index in the case of a single lens, but it is desirable to use low dispersion glass in order to suppress the occurrence of axial chromatic aberration.

The data of the optical system of the second embodiment, which is the entire optical system including the objective optical system and the imaging optical system of the present invention, is as follows. Second embodiment Object distance = -30, incident NA = 0.0033 (F number = 28.574) Angle of view = 61.3 ° (image height = 3.27) r ₁ = ∞ d ₁ = 0.8000 n ₁ = 1.80610 ν ₁ ＝ 40.95 r ₂ ＝ 5.1410 d ₂ = 167.5000 r ₃ = 87.8610 d ₃ = 2.0000 n ₂ = 1.51633 v ₂ = 64.15 r ₄ = ∞ (diaphragm) d ₄ = 2.0000 n ₃ = 1.51633 v ₃ = 64.15 r ₅ = -87.8610 d ₅ = 167.6300 r _{6 = ∞ d 6 = 30.0000 r} 7 = 25.3040 d 7 = 3.0000 n 4 = 1.69680 ν 4 = 55.52 r 8 = -15.5040 d 8 = 1.0000 n 5 = 1.69895 ν 5 = 30.12 r 9 = ∞ d 9 = 45.2800 r 10 _{= 9.0340 d 10 = 3.0000 n 6} = 1.51633 ν 6 = 64.15 r 11 = -5.9710 d 11 = 1.0000 n 7 = 1.71736 ν 7 = 29.51 r 12 = 49.0230 d 12 = 1.0000 r 13 = 9.0340 d 13 = 3.0000 n 8 = 1.51633 ν ₈ = 64.15 r ₁₄ = -5.9710 d ₁₄ = 1.0000 n ₉ = 1.71736 ν ₉ = 29.51 r ₁₅ = 49.0230 β ₂ = -0.958, L _i = 339.6, L _e = 300, L _i / L _e = 1.132 The data of the second embodiment In the motor, r _{1 to} r ₅ are objective optical systems, and r _{7 to} r ₁₅ are image forming optical systems for television cameras. Further, r ₄ is a virtual diaphragm, and r ₆ is a primary image formation.

The objective optical system of the second embodiment is exactly the same as the objective optical system of the first embodiment. Therefore, in this embodiment as well, there is no relay optical system, and the number of lenses arranged in the insertion portion is extremely small. The aberration status of the optical system of this example (the entire optical system combining the objective optical system and the imaging optical system) is well corrected as shown in FIG.

FIGS. 7 and 8 show the third and fourth embodiments of the optical system of the rigid endoscope of the present invention, respectively. The data for these examples are as follows: Third Embodiment object distance = -30, incident NA = 0.002, angle _{= 70 ° r 1 = ∞ d} 1 = 0.8000 n 1 = 1.49216 ν 1 = 57.50 r 2 = 1.6894 ( aspherical) d ₂ = 167.5000 r ₃ = 83.1893 d ₃ = 2.0000 n ₂ = 1.49216 ν ₂ = 57.50 r ₄ = ∞ (aperture) d ₄ = 2.0000 n ₃ = 1.49216 ν ₃ = 57.50 r ₅ = -83.1893 d ₅ = 167.5000 r ₆ = ∞ β ₂ =- 0.978, L _i = 339.8, L _e = 300, L _i / L _e = 1.133 Aspherical surface coefficient P = 0.0500 4th Example Object distance = -30, incident NA = 0.0033, angle of view = 60 ° r ₁ = ∞ d ₁ = 0.8000 n ₁ = 1.80610 ν ₁ = 40.95 r ₂ = 5.1692 d ₂ = 167.5 000 r ₃ = 71.8444 d ₃ = 1.0000 n ₂ = 1.64769 ν ₂ = 33.80 r ₄ = 29.4929 (aperture) d ₄ = 3.0000 n ₃ = 1.51633 ν ₃ = 64.15 r ₅ = -71.8444 d ₅ = 167.5000 r ₆ = ∞ β ₂ = -0.957, L _i = 339.8, L _e = 300, L _i / L _e = 1.133 FIGS. 7, 8 and the above data are All show only objective optics A. In the data of the third embodiment, r ₄ is the virtual diaphragm and r ₆ is the first image formation. Also, in the data of the fourth embodiment, there is a virtual stop at r ₄ and r ₆ is the first image.

A plastic lens is used in the objective optical system of the third embodiment, and the material thereof may be an acrylic material, but other plastics may be used as long as it is a low dispersion optical material. The first lens group is a plano-concave single lens, and the concave surface on the image side is an aspherical surface whose curvature is weakened toward the periphery from the optical axis. The reason for using the aspherical surface whose curvature becomes weaker from the optical axis to the periphery is to correct astigmatism and distortion by this aspherical surface. If the optical system is composed of only spherical surfaces, astigmatism will be largely corrected and overcorrected, and barrel distortion will occur. The distortion at the maximum image height in the primary image formation of the third embodiment is corrected to -1%. The second lens group is a biconvex single lens having the same radius of curvature on both surfaces.

The aspherical surface shape of this embodiment is expressed by the following equation.

Here, z is the distance in the optical axis direction with respect to the intersection of the surface and the optical axis, y is the distance from the optical axis, r is the radius of curvature of the reference spherical surface, and p is a parameter indicating the shape of the quadric surface. Is.

This aspherical surface has no higher-order terms, has a simple shape, and makes an aspherical lens inexpensive.

In the objective optical system of the fourth embodiment, the first lens group is a plano-concave single lens, and the second lens group is a biconvex cemented lens. The objective optical system of the fourth embodiment uses one more lens by using the cemented lens for the second lens group, but has an advantage that axial chromatic aberration and spherical aberration can be corrected well. The cemented lens may be composed of a positive lens having a relatively low refractive index and low dispersion and a negative lens having a high refractive index and high dispersion.

That is, when the positive lens refractive index and Abbe number of this cemented lens are n _p and ν _p , respectively, and the negative lens refractive index and Abbe number are n _N and ν _N , the following condition (4) is satisfied.
To be satisfied. (4) n _p <n _N , ν _p > ν _{N Further, in} this cemented lens, the negative lens may be positioned on the object side as shown in FIG. 8, or the negative lens may be positioned on the image side. May be. The cemented lens may have a plano-convex shape or a meniscus shape instead of the concavo-convex shape as in the embodiment.

Next, the frame structure of the objective optical system is as shown in FIG. 11, for example. In this figure, the observation system tube 9 is composed of a single pipe that holds the objective optical system, and the outer diameter of the lens is fitted into the pipe, and the spacer 10 is used to fix the lens. The spacer 10 is made of metal or synthetic resin, and its inner surface is preferably roughened, and more preferably black. If the inner surface of the spacer is a mirror surface and has a high reflectance, the light reflected by the inner surface of the spacer reaches the image plane and flares, which is not preferable.

Next, the eyepiece optical system and the imaging optical system in the optical system of the present invention will be described respectively. The eyepiece optical system used in the rigid endoscope of the present invention has a configuration (r _{7 to} r shown in FIG. 5, for example.
₂₁ ), this optical system is the primary image formation I ₂ by the objective optical system.
It has the role of a magnifying glass to see (r ₆ ). However, since the primary image formation by the objective optical system is an inverted image, it is necessary to obtain an erect image by the entire optical system including the objective optical system. Therefore, in the eyepiece optical system used in the present invention, image transmission is performed once in the eyepiece optical system to form a secondary image formation I ₂ (r ₁₈ ).
The next image formation I ₂ is observed. That is, unless the secondary image formation I ₂ is formed in the eyepiece optical system, the observed image becomes an inverted image, which is not preferable. Further, since the objective optical system has a simple structure, it is difficult to sufficiently correct the aberration by the objective optical system itself. Therefore, in the optical system of the present invention, aberration correction is performed by the entire optical system including the objective optical system and the eyepiece optical system. In other words, the aberration that cannot be corrected by the objective optical system is focused on.

For example, in the first embodiment of the optical system of the present invention, since the objective optical system is composed of only a single lens, the axial chromatic aberration is insufficiently corrected. In order to correct this with the eyepiece optical system, at least two cemented lenses are used in the eyepiece optical system to overcorrect the axial chromatic aberration in the eyepiece optical system, thereby eliminating the axial chromatic aberration in the undercorrected objective optical system. The axial chromatic aberration of the eyepiece optical system, which is overcorrected, is corrected so that the axial chromatic aberration of the entire optical system is favorably corrected.

Further, in order to keep the cost of the objective optical system low, if the precision of the parts is lowered, the fluctuation of the position of the primary image formation in the optical axis direction becomes large and the focus precision deteriorates. In order to correct this, it is desirable to provide a focusing mechanism in the eyepiece optical system. As a focusing mechanism by the eyepiece optical system, it is possible to move the entire eyepiece optical system along the optical axis and inner focus for moving a part of the lenses in the eyepiece optical system along the optical axis.

Further, it is desirable to provide a field stop for the secondary image formation I ₂ or the primary image formation I ₁ . By providing this field stop at the above position, it is possible to prevent the boundary of the field of vision from becoming unclear, and to prevent flare due to light from outside the field of view.

Next, in the rigid endoscope of the present invention, an image forming optical system used in the case of a method of observing on a television monitor will be described. This imaging optical system is, for example, r in FIG.
Shows in ₇ ~r _15, 1 by the objective optical system image formation I ₁
It has a role of relaying (r ₆ ) to the image pickup surface of the solid-state image pickup device. Similar to the above-mentioned eyepiece optical system, aberration correction is performed in the entire optical system including the objective optical system and the imaging optical system. Therefore, aberrations that cannot be corrected by the objective optical system are mainly corrected. In particular, the axial chromatic aberration is overcorrected by using at least two cemented lenses in the imaging optical system, which corrects the undercorrected axial chromatic aberration of the objective optical system to obtain the axial chromatic aberration of the entire optical system. Is corrected well.

Also in the case of a rigid endoscope which is observed on this television monitor, it is preferable that the television camera adapter is provided with a focusing mechanism. As the focusing mechanism, either a method of extending the entire image forming optical system or an inner focus method using some lenses of the image forming optical system is possible. Further, by providing a diaphragm at the primary image forming position, the boundary of the visual field can be made clear and flare can be prevented.

The above-described rigid endoscope of the present invention is mainly configured to make a part (insertion portion) of the component disposable, but the rigid endoscope to be repeatedly used without being disposable is also used. The structure of the invention can be applied, thereby making it a low-cost rigid endoscope. In that case, for example, in the configuration shown in FIG. 1, the insertion section 1 and the eyepiece section 2 may have an integral structure that cannot be separated. Further, in the case of the configuration shown in FIG. 2, the insertion portion 1 and the television camera adapter 3 may be integrally structured so that they cannot be separated. Further, all of the insertion section 1, the TV camera adapter 3, and the TV camera 4 including the TV camera 4 may be an inseparable integral structure.

That is, the photographing section and the insertion section, which are integrally formed and include the image forming optical system 7 and the solid-state image pickup device, may have a non-separable integral structure.

Even in the case of the rigid mirror which can be repeatedly used as described above, the reduction of the number of optical elements by omitting the relay lens is advantageous in terms of cost and assembly.

The present invention includes not only the rigid endoscope described in the claims but also the embodiments described in (1) to (10) below.

(1) In the above-mentioned objective optical system, the first lens group forms a virtual image in the vicinity of the distal end of the insertion part, which is reduced to a size equal to or smaller than the outer diameter of the first lens group,
The rigid endoscope according to claim 3, wherein the second lens group forms a primary image of an object near the proximal end of the insertion portion.

(2) The rigid endoscope described in the item (1), which satisfies the following condition (1), where β ₂ is the magnification of the second lens group with respect to the object point at infinity. (1) 0.7 <| β ₂ | <1.5 (3) Let L _{i be} the distance from the first surface of the objective optical system to the primary image formation, and let L _{e be} the effective length of the insertion portion. At the time, the rigid endoscope described in the item (1), which satisfies the following condition (2). (2) 0.7 <L _i / L _e <1.5 (4) The first lens group is a single lens having a concave surface on the image side. The rigid endoscope described in (1), (2), or (3) of the above.

(5) Claims 1, 2, or 3 in the claims, wherein the second lens group is a single lens or a cemented lens.
Alternatively, the rigid endoscope described in (1), (2), (3) or (4) above.

(6) The rigid endoscope described in the item (5), wherein the second lens group is a single lens and satisfies the following condition. (3) n ₁ > n ₂ , ν ₁ <ν ₂ (7) The above second lens group is a cemented lens of a positive lens and a negative lens, and satisfies the following condition (4): (5)
The rigid endoscope described in paragraph. (4) n _N > n _p , ν _N <ν _p (8) The optical system of the eyepiece described above allows the whole or a part of the optical system to move along the optical axis for focusing. The rigid endoscope according to claim 1 in the range of.

(9) An optical system in which the optical system of the eyepiece section receives the light from the primary image formation by the objective optical system to form the secondary image formation of the object and the light from the secondary image formation. 1. An optical system for converting a light beam into a substantially parallel light beam.
Rigid endoscope described in.

(10) The television photographing device comprises an adapter section including at least a part of an image forming optical system, and a television camera head detachable from the adapter and including the image pickup means. Claim 2 in the range of
Rigid endoscope described in.

[0058]

According to the rigid endoscope of the present invention, the insertion portion has a simple structure, and in particular, an optical system which does not use a relay optical system in the endoscope optical system and has a simple objective optical system is required. The performance is obtained and the cost of the disposable insertion part is reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a rigid endoscope of the present invention.

FIG. 2 is a diagram showing another example of the rigid endoscope of the present invention.

FIG. 3 is a diagram showing a configuration using a sterilizing cover for the rigid endoscope shown in FIG.

FIG. 4 is a diagram showing a relationship between a lens arrangement of an objective optical system used in a rigid endoscope and a position of primary image formation.

FIG. 5 is a diagram showing the configuration of a first embodiment of the optical system of the rigid endoscope of the present invention.

FIG. 6 is a diagram showing a configuration of a second embodiment of the optical system of the rigid endoscope of the present invention.

FIG. 7 is a diagram showing the configuration of a third embodiment of the optical system of the rigid endoscope of the present invention.

FIG. 8 is a diagram showing the configuration of a fourth embodiment of the optical system of the rigid endoscope of the present invention.

FIG. 9 is an aberration curve diagram of the first example.

FIG. 10 is an aberration curve diagram of the second embodiment.

FIG. 11 is a view showing an example of the frame structure of the insertion portion of the rigid endoscope of the present invention.

FIG. 12 is a diagram showing an example of a prism for perspective use used in the objective optical system of the rigid endoscope of the present invention.

FIG. 13 is a diagram showing a configuration of a conventional rigid endoscope.

[Explanation of symbols]

Adapter 1 insertion portion 2 eyepiece 3 television camera 4 television camera 5 objective optical system 6 eyepiece optical system 7 forming optical system I ₁ 1 primary image

Claims (3)

[Claims] 1. An insertion part having a distal end and a proximal end, which is inserted into an observation site from the distal end side, and an eyepiece connected to the proximal end of the insertion part. An objective optical system is included in the insertion portion, a primary image formation of an object is formed by the objective optical system, and the objective optical system is formed in the eyepiece portion.
A rigid endoscope in which an eyepiece optical system that directly receives the light from the next image formation and emits the light as a substantially parallel light beam is arranged, and the insertion portion and the eyepiece portion are detachably configured. 2. An insertion section having a distal end and a proximal end, the insertion section being inserted into the observation site from the distal end side, and a television photographing device connected to the proximal end of the insertion section. An objective optical system is included in the insertion portion, and a primary image formation of an object is formed by the objective optical system. The television photographing device receives the light from the primary image formation formed by the objective optical system. A rigid endoscope in which an optical system that directly receives and forms an image on an image pickup means in the television photographing device is arranged, and the insertion section and the television photographing device are detachably configured. 3. The objective optical system comprises a negative first lens group arranged near the distal end of the insertion section and a positive second lens group arranged in the middle section of the insertion section. Or the rigid endoscope of 2.