JP2000221416A - Optical path conversion optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compact optical path conversion optical system realizing the side vision at about 90 deg. and housed in one pipe by constituting the system of a 1st optical member, a 2nd optical member, a light shielding plate and a concave lens. SOLUTION: Light beams (a), (b) and (c) ((a) is a light beam along an optical axis O, (b) is either peripheral light beam and (c) is other peripheral light beam) from an examinee introduced in the 2nd optical member 2 through a cover glass CG, the concave lens L and an aperture SH1 are respectively reflected by 4th and 3rd reflection surfaces 2c and 2b, introduced in the 1st optical member 1 through a bonded surface 1d, and further reflected by 2nd and 1st reflection surfaces 1b and 1a and guided to an objective lens L1. Thus, a hard mirror capable of realizing the side vision at 90 deg. is provided. A field-direction conversion optical system consisting of the 1st and the 2nd optical members 1 and 2, the light shielding plate SH and the concave lens L is compactly housed in the pipe P so as to be fit to the outside shape of the tip part of the needle- like constituted mirror.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical path changing optical system,
In particular, the present invention relates to a visual field conversion optical system suitable for a side-view, front-oblique or rear-oblique rigid scope.

[0002]

2. Description of the Related Art Generally, a distal end portion of an endoscope is provided so that a lens system disposed inside the endoscope does not directly contact the outside air.
It must be sealed by a cover glass. Therefore, in any of the direct-viewing, oblique, and side-viewing types, it is required that the optical system be designed to be compact so as to fit in one pipe. Various proposals have hitherto been made to meet these demands.

[0003]

FIG. 7 shows, as a typical example of a conventional oblique optical system, a 70-degree oblique view conversion optical system disclosed in Japanese Patent Application Laid-Open No. 59-87403. In the prism system, side view (90-degree direction) cannot be realized. Since this to the side vision, and at the same time by changing the angle of the first reflecting surface R bending the optical axis in the direction of 90 degrees, the light along the upper surface of the parallel plate P ₁ of the top in the longitudinal direction The angle must be set so as to be parallel to the axis (emission optical axis) O, and the concave lens L
An optimal position is searched for so that the outer diameter of the optical axis does not interfere with the first reflecting surface R. Then, the position at which the optical axis bent by 90 degrees exits the prism P ₂ is positioned above the optical axis O. This is because the cover glass cannot be accommodated in the pipe when the concave lens L is placed thereon.

FIG. 8 shows a typical example of a conventional 90-degree side-view optical system disclosed in Japanese Patent Laid-Open No. 9-294709. In this example, a concave lens L on a side-view prism LP is shown. Is protruding significantly upwards and is not contained within a single pipe. Further, even if the exit surface of the prism parallel to the longitudinal direction in this prism shape is lowered, it is not possible to dispose the prism at a sufficiently lower position while avoiding interference with the outer diameter of the concave lens L disposed thereon. Also, in this example, the two prisms are bonded with an adhesive, and the total reflection or transmission is selectively used at the bonding surface according to the incident angle. However, if the thickness of the bonding agent is thin, light is not totally reflected. Therefore, the work of joining the parts is difficult and the workability is poor.

FIG. 9 shows a conventional perspective optical system disclosed in
110-degree rear view disclosed in
Although the field-of-view conversion optical system is shown, this system
Board P ₁Are arranged in parallel with the optical axis O while ensuring the predetermined optical performance.
Can not be placed, so side view (90 degrees) can be realized
Absent.

As described above, a field conversion optical system using a side-viewing prism and incorporating the entire related optical system in a single pipe has not yet been proposed. On the other hand, in brain surgery, minimally invasive surgery has been desired, and a technique of using a pinhole surgery to make a thin and deep hole in the brain and use an endoscope together under an operating microscope has been spreading. . The purpose of the combined use with the endoscope is to observe a blind spot of a microscope in a pinhole. At present, a 70-degree oblique view is used.
0 degree side viewing has come to be desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a compact optical path changing optical system which can be accommodated in a single pipe when viewed from the side at approximately 90 degrees. Is to provide.

[0008]

In order to achieve the above object, an optical path changing optical system according to the present invention is housed in an elongated housing, and traces an optical path from an exit side to an entrance side in reverse. A first optical member having a first reflecting surface for bending an optical axis along a longitudinal direction of the housing downward, and a second reflecting surface for bending an optical axis bent by the first reflecting surface forward and upward; and the housing. A third reflecting surface, which is accommodated in the first optical member and is disposed adjacent to the front of the first optical member and which bends an optical axis bent by the second reflecting surface downward, and an optical axis bent by the third reflecting surface And a fourth reflecting surface that bends a predetermined upward direction.

According to the present invention, the optical path conversion optical system further includes a third optical member housed in the housing and disposed above the second optical member.

Further, according to the present invention, the second optical member and the third optical member are arranged with a slight air gap.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on illustrated embodiments. FIG. 1 is a longitudinal sectional view of a distal end portion of a rigid mirror in which a first embodiment of an optical path changing optical system according to the present invention is incorporated as a viewing direction changing optical system, and FIG. 2 is a bottom view of a light shielding plate. In the figure, T is a stainless steel tube configured as an elongated housing, GP is a guide pipe inserted and fixed in the stainless steel tube T, P is a pipe press-fitted in the guide pipe GP, and O is a longitudinal direction of the stainless steel tube T The optical axis (emission optical axis) 1 is fixed in the pipe P, and the first reflecting surface 1a for bending the optical axis O downward and the optical axis bent by the first reflecting surface 1a are positioned in front of the stainless steel tube T. The first optical member 2 having a second reflecting surface 1b to be bent and a spherical surface 1c concentric with the optical axis O is disposed on the front side of the first optical member 1 and joined to the joining surface 1d of the first optical member 1. The third reflecting surface 2b for bending the optical axis of the reflected light from the light introducing surface 2a and the second reflecting surface 1b introduced from the light introducing surface 2a downward, and the optical axis bent by the third reflecting surface 2b Side view SH, which is provided on the third reflecting surface 2b and allows the reflected light from the fourth reflecting surface 2c to pass therethrough, the second optical member having a fourth reflecting surface 2c that is bent in a direction perpendicular to the optical axis O. shading plate, L is the installed concave to match the opening SH ₁ on the light shielding plate SH, CG is a cover glass attached to a liquid-tight manner to stainless steel tubing T in alignment with the concave lens L having an aperture SH ₁ of , LG are light guides for guiding illumination light from a light source (not shown) to illuminate the field of view of the subject, L ₁
Is an objective lens fitted to the pipe P.

[0012] Here, although once separate the objective lens L ₁ and the field conversion optical system is sometimes collectively both is considered that the side-view type objective lens. Also, the configuration has been described from the first optical member 1 side for convenience, but since the endoscope is used so that light travels from the second optical member 2 to the first optical member 1, the actual optical path is This is the opposite of the description here.

In the above case, the first and second optical members 1, 2
Is composed of a prism of optical glass, the apex angle of the first optical member 1 (the angle between the first reflection surface 1a and the second reflection surface 1b) is 20 degrees, and the second reflection surface 1b is It has a parallel bottom. The optical axis bent at the first reflecting surface 1a has an inclination angle of 40 degrees with respect to the optical axis O. The refractive index of the first optical member 1 is set to 1.88, and the first reflecting surface 1a totally reflects between the air layer (refractive index 1.0) and the adhesive (refractive index 1.52). It has become. In the first reflecting surface 1a, the critical angle with air is 32 degrees, the critical angle with adhesive is 53 degrees, and the incident angle of light rays is 60 to 80 degrees, which is larger than any of the critical angles. As a result, the air part and the adhesive part are totally reflected. Further, since the position of the effective diameter at the time of reflection and the position of the effective diameter at the time of transmission can be separated at the boundary surface with the second optical member 2, the reflection at the boundary surface with the second optical member 2 is reflected on the first reflection surface 1 a. The bonding may be performed after depositing the metal film only on the portion.

The critical angle of the second reflection surface 1b with the air is 32 degrees, and the incident angle of the light beam is 40 degrees to 60 degrees, so that the light is totally reflected. Although a film may be deposited and reflected, in this embodiment, a metal film is intentionally applied within the effective diameter in order to transmit light other than the normal optical path and to reduce ghost and flare rays as much as possible. Outside the effective diameter, black paint is applied to shield light.

The second reflecting surface 1b with respect to the boundary between the joining surface 1d of the first optical member 1 and the light introducing surface 2a of the second optical member 2
The incident angle of the reflected light from the glass is 20 degrees to 40 degrees, and the critical angle between the adhesive and the glass is 52 degrees, so that the reflected light can pass through the boundary surface.

The second optical member 2 is a prism having an apex angle of 20 degrees and 25 degrees.
Since it is adhered to the first optical member 2 as a, the third reflection surface 2b is a surface parallel to the optical axis O. The angle formed between the optical axis bent by the second reflection surface 1b and the third reflection surface 2b is 40 degrees, and the refractive index of the second optical member 2 is set so that the light is totally reflected by the third reflection surface 2b. I have. That is, the angle formed by the reflected light from the second reflection surface 1b with respect to the axis perpendicular to the third reflection surface 2b is 40 degrees to 60 degrees, and the critical angle with air at the third reflection surface 2b is 32 degrees. There is total reflection. The optical axis bent at the third reflecting surface 2b has an apex angle of 2
The optical axis O is bent at a plane of 5 degrees (the fourth reflecting surface 2c).
Is deflected in a side viewing direction of 90 degrees. Fourth reflective surface 2
A metal film is deposited on c, and the optical axis bent here passes vertically through the third reflecting surface 2b. Thus transmitted light axis shielding plate SH opening SH ₁ and a concave lens L a through with a stainless tube T which is fixed to the cover glass C
G is transmitted.

[0017] Since this embodiment is constructed as described above, the cover glass CG, light a than the object introduced through the concave lens L and aperture SH ₁ to the second optical member 2,
b, c (a is light along the optical axis, b is one peripheral light, c
Indicates other ambient light) is reflected by the fourth reflecting surface 2c and the third reflecting surface 2b, respectively, as shown in FIG.
Is introduced into the first optical member 1 through the first lens unit 1 and further reflected by the second reflecting surface 1b and the first reflecting surface 1a.
Guided to ₁ . Thus, it is possible to provide a rigid endoscope that can be viewed 90 degrees sideways.

As is apparent from this description, the viewing direction changing optical system including the first optical member 1, the second optical member 2, the light shielding plate SH, and the concave lens L is suitable for, for example, the outer shape of the tip of the needle-shaped rigid mirror. The optical members can be compactly housed in the pipe P so that the optical members can be assembled in the pipe P in advance and fixed, and then the pipe P is pressed into the guide pipe GP to complete the assembly. This is extremely convenient in terms of manufacturing.

In the first embodiment, the position where the light is emitted from the first optical member 1 (the position of the third reflecting surface 2b) can be set at a position further below the extension of the optical axis O. It is. Further, by applying a metal film only to the effective diameter of the reflected light on the bonding surface between the first reflecting surface 1a and the second optical member 2, it is possible to completely eliminate the reflecting portion due to the adhesive, thereby achieving stable production. Will be possible. Further, even if the dimensions of the components vary due to the processing error of the optical member or the like, there is no problem in incorporating the optical member into the pipe P merely by moving the position of the concave lens L back and forth. Even if L moves back and forth, since the oblique surface (first reflecting surface 1a) of the optical member that interferes is located at a distance, there is no problem that assembly becomes impossible. In addition, since the intersection of the optical axis bent by the first reflection surface 1a and the second reflection surface 1b must be set to a position somewhat lower than the extension of the optical axis O, the top of the first optical member 1 The angle is preferably 15 degrees to 30 degrees, and more preferably about 20 degrees to 25 degrees in consideration of workability and a sufficient reduction in the position of the concave lens L. In addition, since the light-shielding plate SH is provided with a step in the thickness direction to serve as a spacer for forming an air layer on the third reflection surface 2b, it is possible to easily assemble the optical system.

FIG. 3 is a longitudinal sectional view of the tip of a rigid endoscope in which a second embodiment of the optical path changing optical system according to the present invention is incorporated as a viewing direction changing optical system. In this embodiment, the second optical member 2
The third embodiment is different from the first embodiment in that the third optical member 3 is interposed between the first lens and the concave lens L, and the second reflection surface 1b is configured to be a total reflection surface without a metal film. That is, in this embodiment, the third optical member 3 configured as a parallel plane plate is disposed on the third reflecting surface 2b of the second optical member 2 via the spacer SP bonded so as to avoid the effective diameter, and the concave lens L and the light shielding plate SH are provided on the third optical member 3. The reason why the air layer is provided between the second optical member 2 and the third optical member 3 by using the spacer SP is that the adhesive for fixing the concave lens L on the third optical member 3 is directly applied to the third reflecting surface 2.
This is to prevent light from being lost if the light is not reflected on the surface b without causing total reflection. As described above, since the second reflection surface 1b has no metal film and is not coated with a black paint, unnecessary light such as flare or ghost is likely to enter.
By arranging the light shielding plate SH as described above, flare and ghost are reduced.

The other constructions and operations of the second embodiment are the same as those of the first embodiment, and will not be described. However, in the second embodiment, the second reflection surface 1b is a total reflection surface. The reflectivity is improved and bright observation is possible. Further, the exit position from the prism, that is, the position of the third reflection surface 2b of the second optical member 2 can be set to be substantially the same as the extension of the optical axis O. Also, even if there is some variation in dimensions due to processing errors and the like of the first and second optical members prism,
There is no problem that the concave lens L moves forward and backward, so that they do not enter the pipe P. Further, even if the concave lens L moves forward and backward, the slope (first reflection surface 1a) that interferes is far away. There is no hindrance to assembly.

In the first and second embodiments, the side view, that is, the case where the incident direction is perpendicular to the exit direction, which has conventionally been difficult to make thin, has been described. However, the present invention is not limited to this. It is possible to provide an optical path conversion optical system that performs various viewing direction conversions. An example will be described below.

FIG. 4 is a sectional view showing a main part of a third embodiment of the optical path changing optical system according to the present invention. In this embodiment, the first optical member is the same as that of the above-described embodiment, and the third optical surface 2b and the fourth optical surface 2c of the second optical member 2 are made parallel to each other, which is the second optical member. Although the exit surface of the prism is formed as a surface different from the third reflection surface, in this configuration, the incident direction is substantially parallel to the optical path from the second reflection surface 1b to the third reflection surface 2b. , A so-called oblique optical system can be realized. In this case, if the third reflection surface 2b and the fourth reflection surface 2c are configured to form an angle, the perspective direction, that is, the direction of the incident optical path changes according to the angle. conventionally,
As described above, not only was it difficult to reduce the thickness of the side-view type, but as is clear from FIGS. In addition, separate parts are required if the viewing directions are different between perspectives. On the other hand, according to the present invention, as described above, the first optical member can be used in common to form various side-view type viewing direction changing optical systems. It is extremely useful in such aspects.

FIG. 5A shows an optical path changing optical system according to the present invention.
It is sectional drawing which shows the principal part of 4th Example. This example
Is that the number of reflections in the second optical member 2 is increased.
Different from the three embodiments. In this case, the second optical member 2 is
The reflection surface R compared to the third embodiment.₁And R_Two
Is increasing. This is the distance from the incident optical path to the exit optical path.
This is useful when you want to take longer. In this example,
Reflective surface R₁Is on the same plane as the third reflection surface 2b, and this surface
And reflective surface R_TwoAre parallel, but the variation shown in FIG.
As in the example, the reflection surface R_TwoIs the third reflecting surface 2b and the reflecting surface R₁
May be inclined with respect to the plane on which there is. In this variant
Is the reflection surface R₁And the surface on which the third reflecting surface 2b is located, and the reflecting surface R
_TwoIs closer to the incident side with respect to the surface where the fourth reflection surface 2c is located.
However, in this configuration, each reflecting surface
Use this effect as the reflection angle gradually decreases
To set various angles between the incident direction and the exit direction
be able to. In this embodiment and the modification, the reflecting surface R₁
And third reflecting surface 2b, reflecting surface R _TwoAnd the fourth reflecting surface 2c are respectively
It is configured to be on the same plane, but one prism
If you try to construct an optical member that
The shape may be complicated and the production may be difficult.
Alternatively, a plurality of prisms may be used.

As is clear from the above description, the optical path changing optical system according to the present invention does not become thicker than the thickness of the first optical member 1, so that it can be an extremely thin optical system. Therefore, the present invention can be widely applied not only to a viewing direction changing optical system of an endoscope such as a rigid endoscope but also to an optical path changing optical system of various optical devices. FIG. 6 is a schematic sectional view showing an example in which the optical path changing optical system described in the first embodiment is used in an electronic camera. In the figure, F represents a finder optical system, OP is the optical path conversion optical system according to the present invention, L ₁ is an objective lens formed of a binding positive lens, IS is an image sensor. As described above, if the optical path conversion optical system OP is used upright, the image sensor IS is arranged on the emission optical path, and these and the finder optical system F are housed in one housing, an ultra-thin electronic camera is obtained. I can do it.

As described above, the optical path conversion optical system of the present invention has the following features in addition to the features described in the claims. (1) When an optical path is traced backward from the exit side to the incident side, a first reflection surface that reflects the exit optical path obliquely in a direction opposite to the incident optical path and an optical path that is reflected by the first reflection surface is an incident optical path. A first optical member having a second reflecting surface that reflects obliquely in the direction of, and obliquely reflects the optical path reflected by the second reflecting surface directly or in the opposite direction to the incident optical path via the reflecting surface. An optical path conversion optical system having different incident and outgoing directions, comprising a second optical member having a third reflecting surface to be turned on and a fourth reflecting surface for directing the optical path reflected by the third reflecting surface to the incident direction.

(2) The optical path according to the above (1), wherein the second reflection surface and the third reflection surface are arranged substantially in parallel with the exit optical path, and the incident direction and the exit direction are substantially orthogonal. Conversion optics.

(3) The optical path conversion optical system according to (1) or (2), wherein the first and second optical members are both prisms.

(4) The optical path changing optical system according to (3), wherein the incident surface of the second optical member and the third reflecting surface are on the same surface.

(5) The optical path conversion optical system according to (3), wherein the incident surface of the second optical member and the third reflecting surface are inclined so as to form a predetermined angle.

(6) When the optical path is traced backward from the exit side to the entrance side, the first reflection surface that reflects the exit optical path obliquely in the direction opposite to the incident optical path, and the optical path that is reflected by the first reflection surface. A first prism having a second reflecting surface obliquely reflecting in the direction of the incident light path, and reflecting the light path reflected by the second reflecting surface either directly or obliquely in the opposite direction to the incident light path via the reflecting surface. And a second prism having a fourth reflecting surface for directing the optical path reflected by the third reflecting surface in the incident direction, and an angle between the first reflecting surface and the second reflecting surface. The first prism is constant, by selectively combining the second prism having a different angle between the third reflection surface and the fourth reflection surface, a plurality of different angles formed between the incident direction and the emission direction. Method of configuring optical path conversion optical system for configuring optical path conversion optical system

[0032]

As described above, according to the present invention, a compact and ultra-thin optical path changing optical system can be provided.
In particular, it is possible to provide a viewing direction changing optical system that can be accommodated in a very fine pipe when applied to a rigid mirror or the like that is viewed from the side (90 degrees) or oblique (70 to 110 degrees).

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a distal end portion of a rigid mirror in which a first embodiment of an optical path changing optical system according to the present invention is incorporated as a viewing direction changing optical system.

FIG. 2 is a bottom view of the light shielding plate used in the first embodiment.

FIG. 3 is a longitudinal sectional view of a distal end portion of a rigid endoscope in which a second embodiment of the optical path changing optical system according to the present invention is incorporated as a viewing direction changing optical system.

FIG. 4 is a sectional view of a main part of a third embodiment of the optical path changing optical system according to the present invention.

FIG. 5A is a sectional view of a main part of a fourth embodiment of an optical path changing optical system according to the present invention, and FIG. 5B is a sectional view showing a modified example thereof.

FIG. 6 is a schematic sectional view showing an example in which the first embodiment of the present invention is applied to an electronic camera.

FIG. 7 is a cross-sectional view of a main part showing a typical example of a conventional 70-degree oblique view conversion optical system.

FIG. 8 is a cross-sectional view of a main part showing a typical example of a conventional 90-degree side-view visual field conversion optical system.

FIG. 9 is a cross-sectional view of a main part showing a typical example of a conventional field-of-view conversion optical system for 110-degree rear view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 First optical member 1a First reflecting surface 1b Second reflecting surface 1c Spherical surface 1d Joining surface 2 Second optical member 2a Light introducing surface 2b Third reflecting surface 2c Fourth reflecting surface 2d Emission surface 3 Third optical member SH Light shielding plate SH ₁ aperture L concave lens L ₁ objective lens CG cover glass P pipe T stainless tube 1G light guide O emission optical axis SP spacer R, R ₁ , R ₂ reflection surface F finder OP optical path conversion optical system IS image sensor

Claims (3)

[Claims] A first reflecting surface which is housed in an elongated housing and bends an optical axis along a longitudinal direction of the housing downward when the optical path traces the light path from the exit side to the entrance side in reverse. A first optical member having a second reflecting surface that bends the optical axis bent by the first reflecting surface forward and upward, and is housed in the housing and is disposed adjacent to and in front of the first optical member, A second optical member having a third reflecting surface for bending the optical axis bent by the second reflecting surface downward and a fourth reflecting surface for bending the optical axis bent by the third reflecting surface upward by a predetermined amount; An optical path conversion optical system characterized by the above-mentioned. 2. The optical path changing optical system according to claim 1, further comprising a third optical member housed in said housing and disposed above said second optical member. 3. The optical path conversion optical system according to claim 2, wherein the second optical member and the third optical member are arranged with a slight air gap.