WO2000046626A1

WO2000046626A1 - Optical-path conversion optical system

Info

Publication number: WO2000046626A1
Application number: PCT/EP2000/000796
Authority: WO
Inventors: Susumu Takahashi
Original assignee: Olympus Winter & Ibe Gmbh
Priority date: 1999-02-03
Filing date: 2000-02-01
Publication date: 2000-08-10
Also published as: DE10080406T1; JP2000221416A

Abstract

Disclosed is a compact optical-path conversion system which is stored entirely within a tubular housing and allows side viewing at an angle of substantially 90 degrees. The optical-path conversion system consists of two prisms (1, 2) each with two reflecting surfaces (1a, 1b, 2b, 2c). The observed object light is reflected consecutively off each surface in the order fourth (2c), third (2b), second (1b), first (1a). The embodiments describe the use of the system in an endoscope and electronic camera. Details deal with avoiding flare and ghost images.

Description

[TITLE]

Opticai-path conversion optical system

[DETAILED DESCRIPTION OF INVENTION]

[0001]

[TECHNICAL FIELD]

This invention relates to the visual-field conversion optical system suitable for a hard optical-path conversion optical-system especially side-view, front perspective, or rear perspective type mirror etc. [0002] [PRIOR ART]

Generally, the point of an endoscope needs to seal with a cover glass so that the lens system arranged on the inside is not to touch the air of outdoor directly. Therefore, a compact design so that an optical system may be settled in one tube in the case of any formats, such as a direct-view, an perspective, and a side view, is required. In order to satisfy these demands, conventionally various proposals are performed.

[0003]

[PROBLEM ADDRESSED]

Fig. 7 shows the visual-field conversion optical system with perspective of a 70 degrees disclosed by the unexamined-Japanese-patent-No. 59-87403 gazette as an example of representation of a conventional perspective optical system. This prism system cannot perform a side view (the direction of 90 degrees). Because, in order to use it the into a side view, the angle of the first reflecting- surface R is changed and an optical axis is bent in a direction of 90 degrees. An angle must be set up so that the upper surface of parallel flat P1 of the upper part may become parallel to optical-axis O along the longitudinal direction (injection optical axis).

The optimum position is looked for so that the outer diameter of concave-lens L arranged the upper surface may not interfere with first reflecting-surface R.Therefore, the optical axis bent 90 degree positions an upper site against optical-axis O.Accordingly,when concave-lens L is set on it,a cover glass can not build in the pipe.

[0004]

Fig. 8 shows the example (unexamined-Japanese-patent-No. 9-294709 gazette) as representation of the side-view optical system of 90 degrees in conventionally.

In this example, concave-lens L on side-view prism LP is protruded largely upward. Therefore, this can not build in one tube.

Moreover, in this prism shape, the injection surface of a prism parallel to a longitudinal direction can be lowered.

It cannot arrange to a downward position sufficiently so that interference with the outer diameter of concave-lens L further arranged on optical-axis may be avoided. Moreover, junction of the two prisms is performed with the adhesive agent in this example.

The total reflection or the transmission is properly used depending on the projection angle at this adhesive surface.

However, if the thickness of an adhesive agent is thin, light will get lost without performing a total reflection. For this reason, the junction work of a component is difficult and operativity is bad.

[0005]

Fig. 9 shows the visual-field conversion optical system of 110 degrees disclosed by the unexamined-Japanese-patent-No. 60-64320 gazette as a conventional perspective optical system.

However, since parallel flat P1 cannot be arranged in this system with a predetermined optical-character ability in parallel with optical-axis O, a side view (90 degrees) is unrealisable.

[0006]

Thus, the visual-field conversion optical system with which the entire optical system using the side-view prism was built in one tube is not yet proposed conventionally.

On the one side, in brain-surgery surgery, low stress surgery is desired and is needed. The technique ( pinhole surgery is called) which opens a thin and deep hole in a brain and uses an endoscope together under an operation microscope has extended.

The objective which uses an endoscope together is the side wall observation which causeses the dead corner of the microscope within a pinhole.

In the present condition, the perspective of70 degrees is used. However, the side view of 90 degrees is desired from the ease of an orientation.

[0007]

This invention is performed in consideration of the above situations. That objective offers the compact optical-path conversion optical system which can be built in one tube at the substantially side view of 90 degrees.

[0008] [SOLUTION OF THE INVENTION]

In order to attain the above-mentioned objective, an optical-path conversion optical system according to the invention contained in the long and slender housing and comprising the first optical member provided with the first reflecting surface which bends downward the optical axis along the longitudinal direction of the housing when an optical path is conversely followed toward an incidence side from an injection side, and the second reflecting surface which bends the optical axis bent by the first reflecting surface to the front upper part, and the second optical member contained in the housing and adjacently arranged ahead of the first optical member and comprising a third reflecting surface bending downward the optical axis bent by the second reflecting surface, and the fourth reflecting surface bending the optical axis bent by the third reflecting surface to the predetermined upper part.

[0009]

According to this invention, then optical-path conversion optical system further comprises the third optical member contained in the housing and arranged on the upper part of the second optical member.

[0010]

Moreover, according to this invention, the second optical member and the third optical member are arranged small air spaces.

[0011] [Embodiment]

Hereafter, the embodiment of this invention explains based on the example . Fig. 1 is a longitudinal sectional view of the hard mirror point which the optical- path conversion optical system of the first example according this invention is built in a conversion optical system with the direction of a visual field. Fig. 2 is a bottom view of a shading board.

In the figure.T is the stainless-steel tube comprised as a long and slender housing .

GP is inserted within stainless-steel tube T, And it is the fixed guide tube. P is the tube inspissated in the guide tube GP. O is an optical axis (injection optical axis) along the longitudinal direction of stainless-steel tube T.

1 is the first optical member fixed in tube P.and provided a first reflecting- surface 1 a which bends downward optical-axis O , second reflecting-surface 1 b which bends the optical axis bent by first reflecting-surface 1 a ahead of stainless-steel tube T, and optical-axis 0 and spherical-surface 1c of the same core as optical-axis O.

2 is the second optical member arranged on the front side of the first optical member 1 and provided an optical guide surface 2a by which junction was performed to the bonding planes 1d of the first optical member 1 , third reflecting-surface 2b which bends downward the optical axis of the reflected light of second reflecting-surface 1 b guided from the optical guide surface 2a, and fourth reflecting-surface 2c which bends the optical axis bent by third reflecting-surface 2b for the direction of side view, i.e., an orthogonal direction with optical-axis O.

SH is a shading board provided on third reflecting-surface 2b and having the aperture SH1 for passing reflected light from fourth reflecting-surface 2c .

L is the concave lens installed so that it might adjust with an aperture SH1 on the shading board SH.

CG is the cover glass which adjusts in concave-lens L and was mounted stainless-steel tube T at the fluid-tight manner.

LG is a light guide for leading an illumination light from a light source(not- shown), in order to illuminate the field-of-view range of an examined object.

L1 is the objective lens fitted by tube P.

[0012]

In addition, the objective lens L1 and the visual-field conversion optical system are divided.

However, the both may be observe a side-view type objective lens.

Moreover, the concept was explained from side of the first optical-member 1 for convenience.

However, it is used so that a light may progress from the second optical member 2 to the first optical member 1 in the endoscope.

Therefore, the actual optical path is contrary to explanation herein as mentioned later.

[0013] In the above-mentioned case, the first and the second optical member 1 and 2 consist of the prism of an optical glass.

The top angle (angle of first reflecting-surface 1 a between second reflecting- surface 1 b ) of the first optical member 1 is 20 degrees. Second reflecting-surface 1 b comprises a base parallel to optical-axis O. The optical axis bent by first reflecting-surface 1 a is the inclination with angle of 40 degrees to optical-axis O.

The refractive index of the first optical member 1 is set 1.88. The total reflection of the first reflecting-surface 1 a is performed between an air space (refractive index 1.0) and an adhesive agent (refractive index 1.52). Moreover, in reflecting-surface 1 a, the critical angle with air is 32 degrees. The critical angle with an adhesive agent is 53 degrees. The projection angle of a light ray is 60 degrees or 80 degrees. Therefore, it has an angle larger than an any critical angle. Therefore, a total reflection is performed in an air part and an adhesive-agent part.

Moreover, the position of the effective diameter at the time of reflection and the effective diameter at the time of a transmission can be isolated at the interface boundary with the second optical member 2.

Therefore, after depositing a metal film only to the reflecting part of the interface boundary with the second optical member 2 on first reflecting-surface 1 a, it may be made to perform junction.

[0014]

In second reflecting-surface 1 b, the critical angle with air is 32 degrees. Because the projection angle of a light ray is the angle of 40 degrees or 60 degrees, the total reflection of the light is performed.Therefore,the total reflection may performed or a metal film may be deposited to make reflection. In order to lose the light ray with which a light transmits except the optical path of a normal and produces a ghost and a flare in this example, it applies a metal film in an effective diameter.

And a black coating material is painted and shaded out of an effective diameter.

[0015]

The projection angle of the reflected light from second reflecting-surface 1 b to the interface boundary with the bonding plane id of the first optical member 1 and guide optical surface 2a of the second optical member 2 is 20 degrees or 40 degrees.

Since the critical angle of an adhesive agent and glass is 52 degrees, the reflected light can perform the transmission of the interface boundary.

[0016]

The second optical member 2 is a prism with which a top angle consists of 20 degrees and 25 degrees.

Because the surface with top angle of 20 degrees is bonded to the first optical member 2 as optical guide surface 2a, third reflecting-surface 2b is a surface parallel to optical-axis O.

The angle of the optical axis which was bent at second reflecting-surface 1 b and third reflecting-surface 2b is 40 degrees.

The refractive index of the second optical member 2 is set up so that a total reflection may be performed at third reflecting-surface 2b.

That is, the angle of the reflected light from second reflecting-surface 1 b to an shaft perpendicular to third reflecting-surface 2b is 40 degrees or 60 degrees.

In third reflecting-surface 2b, because the critical angle with air is 32 degrees, the total reflection of the light is performed.

The optical axis bent at third reflecting-surface 2b is bent on the surface of 25 degrees of a top angle (fourth reflecting-surface 2c).

And a deflection is performed in the direction of a side view of 90 degrees to optical-axis O.

Because fourth reflecting-surface 2c is depositing a metal film, the bent optical axis performs perpendicularly the transmission in the third reflecting-surface 2b.

In this way, the transmitted optical axis performs the transmission in the cover glass CG fixed by stainless-steel tube T through the aperture SH1 and concave-lens L of the shading board SH.

[0017]

This example is comprised as mentioned above.

Therefore, the lights a, b, and c (a shows light along an optical axis,b shows one peripheral light and c shows the other peripheral light) from the examined object guided within the second optical member 2 via cover-glass CG, concave- lens L, and the aperture SH1 are reflected by fourth reflecting-surface 2c and third reflecting-surface 2b such as illustration, respectively.

And, a light is guided within the first optical member 1 via bonding planes 1 d.

Furthermore the light was reflected at second reflecting-surface 1 b and first reflecting-surface 1 a to guide to an objective lens L1.

In this way, the hard mirror in which a side view is possible 90 degrees is obtained .

[0018]

The conversion optical system of the direction of a visual field which consists of the first optical member 1 , the second optical member 2, the shading board SH, and concave-lens L clearly by above-mentioned explanation can be contained in a compact within tube P so that the appearance of a needlelike hard mirror point may be adapted.

Moreover, after including these optical members beforehand within tube P and fixing, an assembly can be completed only by inspissating the tube P within the guide tube GP. Therefore, it is extremely convenient for manufacture.

[0019]

In the first above-mentioned example.the shot position (position of third reflecting-surface 2b) of the light from the first optical member 1 is possible to set a lower position from the extension line of optical-axis O. Moreover, a metal film is first applied only to the effective diameter of reflected light at the adhesive surface of first reflecting-surface 1 a and the second optical member 2. In this way, manufacture is stably possible because the reflecting part by the adhesive agent can completely be eliminated. Moreover, even when variation is in the size of a component according to the process error of an optical member etc., the position of concave-lens L moves only forward and backward.

Therefore, there is no problem to build in an optical member within tube P. Moreover, even when concave-lens L moves forward and backward, the inclined plane (first reflecting-surface 1 a) of an optical member in which it interferes is in a separated position. Therefore, an assembly is not impossible. Moreover, in order to perform the intersection position of the optical axis bent at first reflecting-surface 1 a and second reflecting-surface 1b to a position to some extent lower than the extension line of optical-axis O.the top angle of the first optical member 1 has 15 degrees or 30 degrees, desirablely Furthermore.when considering workability and lowering the position of concave- lens L sufficiently, about 20 degrees or about 25 degrees are more desirable. In addition, the shading board SH composes the spacer for making an air space on third reflecting-surface 2b with the difference in level in the thickness direction. Therefore.the assembly of an optical system may be easily.

[0020]

Fig. 3 is a longitudinal sectional view of the hard mirror point which built in the optical-path conversion optical system of the second example according to this invention as a conversion optical system of the direction of a visual field.

In this example, the third optical member 3 interposes between the second optical member 2 and concave-lens L,and second reflecting-surface 1 b has not metal film.

Therefore, it is different from the first example at the point which comprises a total-reflection surface is composed by these component.

That is, the third optical member 3 which is composed as a plane-parallel plate via spacer SP which avoids an effective diameter and was bonded on third reflecting-surface 2b of the second optical member 2 is arranged.

Concave-lens L and the shading board SH are installed on this third optical member 3.

An air layer is formed between the second optical member 2 and the third optical member 3 by being used spacer SP.

The reason is as follows.

If the adhesive agent for fixing concave-lens L on the third optical member 3 is directly attached on third reflecting-surface 2b, a light will cause a quantity-of- light loss without performing a total reflection.

There is no metal film on second reflecting-surface 1 b as mentioned above, and the black coating material is not applied. Therefore, the unnecessary light which causes a flare and a ghost is simple to enter. However, a flare and a ghost can be made small by arranging the third optical member 3 and the shading board SH as mentioned above.

[0021 ]

Because other components and effects of the second example are the same as that of the first example, an explanation is not omitted.

Since second reflecting-surface 1 b is a total-reflection surface in the second example, a reflecting rate improves and the bright observation is possible.

Moreover, the shot position from a prism, i.e., position of third reflecting-surface

2b of the second optical member 2 can set as the almost same position as the extension line of optical-axis O.

Even when some variations are in a size according to the process error etc, of the prism which are the first and a second optical member, the position of concave-lens L moves only forward and backward.

Therefore, there is no problem in which these built into tube P.

Moreover even when a concave lens moves forward and backward, the inclined plane (first reflecting-surface 1a) in which it interferes is separated. For this reason, trouble is not caused to an assembly.

[0022]

In conventionally, the side view which the direction of incidence, and the direction of an injection is the perpendicular can compose with thin component in the first and the second example.

However, this invention is not limited to this and can offer the opticai-path conversion optical system which performs the various direction conversion of a visual field. That example is shown below.

[0023]

Fig. 4 is a sectional view showing the principal part of the third example of the optical-path conversion optical system according to this invention. A first optical member in this example uses the same member as an example as stated above.

In the example, third reflecting-surface 2b and fourth reflecting-surface 2c of the second optical member 2 are made into a parallel and the injection surface of the prism which is the second optical member is formed the surface other than the third reflecting surface.

However.in with this component, the direction of incidence is substantially parallel the optical path which reaches in third refiecting-surface 2b from second reflecting-surface 1 b. Therefore, the so-called perspective optical system is realisable. If the third reflecting-surface 2b and fourth reflecting- surface 2c comprises with an angle in this case, the variation of the direction of an perspective, i.e., the direction of an incident-light path will be performed depending on the angle. Conventionally, in such as previous statement, a side-view type was not only difficult to compose thinly, but a side view and an perspective does not have common property in the shape of an optical component clearly from Figs. 7 or 9 and they needed to manufacture completely separately, respectively.

The separate component was required when the direction of a visual field was different between perspectives.

On the other hand, according to this invention, the first optical member can be manufactued commmonly as above mentioned .

And the conversion optical system of the various direction of a side-view type visual field can be composed.

Therefore, it is extremely useful in terms of common of a component, or common of a manufacture process.

[0024]

Fig. 5 (a) is a sectional view showing the principal part of the optical-path conversion optical system of the fourth example according to this invention.

In this example, it is different from the third example to increase the frequency of reflection within the second optical member 2.

In this case, the second optical member 2 is a prism.

Compared with the third example, reflecting surfaces R1 and R2 increase.

This is useful to take a long distance from an incident-light path to an injection optical path.

In this example, a reflecting surface R1 is an identical surface with third reflecting-surface 2b.

This surface and reflecting surface R2 are parallel.

However, a reflecting surface R2 may be inclined to the existing surface of third reflecting-surface 2b and the reflecting surface R1 such as the modification shown in Fig. 5 (b).

In this modification, the space of the existing surface of a reflecting surface R1 and third reflecting-surface 2b and the existing surface of a reflecting surface

R2 and fourth reflecting-surface 2c is narrow with approaching an incidence side.

However, because the angle of reflection in each reflecting surface becomes small gradually in this component.

The angle of the direction of incidence between the direction of an injection can also be set up variously using the effect. In this example and modification, a reflecting surface R1 and third reflecting- surface 2b ,the reflecting surface R2 and fourth reflecting-surface 2c may consist in an identical surface, respectively.

However, when it comprises the optical member with many frequencies of reflection with one prism, a shape is complicated and manufacture is difficult. Therefore, it may be made to compose from a multiple prism depending on necessity.

[0025]

By the above explanation, clearly, as the optical-path conversion optical system according to this invention is not thick more than the thickness of the first optical member 1 , it can form an extremely thin optical system.

Therefore, this invention is not only used as an optical-path conversion optical system of the conversion optical system of the direction of a visual field of endoscopes, such as a hard mirror, but is applied a various optical instrument.

Fig. 6 is a schematic sectional view showing an example which utilised the optical-path conversion optical system explained in the first example for the electron camera.

In the figure, F is a finder optical system .

OP is an optical-path conversion optical system based on this invention.

L1 is the objective lens which consists of a joint positive lens.

IS is an image sensor.

In this way, the optical-path conversion optical system OP is assembled with a stand.

Image sensor IS is arranged on an injection optical path.

If these and finder optical-system F are built in one housing, a ultra-thin type electron camera will be obtained.

[0026]

As explained above, the optical-path conversion optical system of this invention has the following characteristic as well as the characteristic described in the claim.

(1 ) The optical-path conversion optical system with which the direction of the incidence and the direction of the injection differ from each other and comprising the first optical member provided with the first reflecting surface which reflects an injection optical path against an incident-light path in a reverse and diagonal direction, and the second reflecting surface which reflects diagonally the optical path reflected at the first reflecting surface in the direction of an incident-light path when following an optical path conversely toward an incidence side from an injection side ,and the second optical member provided with the third reflecting surface which are diagonally reflected the optical path reflected at the second reflecting surface in a reverse direction against an incident-light path via a reflecting surface directly or indirectly,and the fourth reflecting surface which directs the optical path reflected at the third reflecting surface against the direction of the incidence. [0027]

(2) An optical-path conversion optical system described in above-mentioned

(1 ), wherein the second reflecting surface and the third reflecting surface are arranged in parallel on an injection optical path substantially.and the direction of incidence and the direction of an injection cross orthogonally .substantially.

[0028]

(3) An optical-path conversion optical system described in above-mentioned

0). or (2) wherein the first and second optical member are any prisms.

[0029]

(4) An optical-path conversion optical system described in above-mentioned (3) whichin the plane of incidence of the second optical member and the third reflecting surface is in an identical surface.

[0030]

(5) An optical-path conversion optical system described in above-mentioned (3) wherein the plane of incidence of the second optical member and the third reflecting surface are inclined to have a predetermined angle.

[0031]

(6) A composition method of a plural of an optical-path conversion optical system which angle of the direction of the incidence between the direction of the injection differ from and comprising the first prism provided with the first reflecting surface which reflects an injection optical path against an incident- light path in a reverse direction and diagonally, and the second reflecting surface which reflects diagonally the optical path reflected at the first reflecting surface for the direction of an incident-light path when following an optical path conversely toward an incidence side from an injection side,, and the second prism provided with the third reflecting surface which are diagonally reflected the optical path reflected at the second reflecting surface in a reverse direction against an incident-light path via a reflecting surface directly or indirectly.and the fourth reflecting surface which directs the optical path reflected at the third reflecting surface for the direction of the incidence, the second prism with which the angle of the third reflecting surface between the fourth reflecting surface is different is combined selectively with the first prism which angle of the first reflecting surface between the second reflecting surface is constant.

[0032]

[EFFECT OF THE INVENTION]

According to this invention, a compact and ultra-thin type optical-path conversion optical system can be offered.

When applying to the hard mirror of a side view (90 degrees) or an perspective (70 or 110 degrees) etc. especially, the accomodatable direction conversion optical system of a visual field can be offered also in the tube of an extra-fine.

[BRIEF EXPLANATION OF DRAWINGS] [FIGURE 1]

It is the longitudinal sectional view of the hard mirror point which built in the first example of the optical-path conversion optical system by this invention as a direction conversion optical system of a visual field.

[FIGURE 2]

It is the bottom view of the shading board used for the first example.

[FIGURE 3]

It is the longitudinal sectional view of the hard mirror point which built in the second example of the optical-path conversion optical system by this invention as a direction conversion optical system of a visual field. [FIGURE 4]

It is the principal-part sectional view of the third example of the optical-path conversion optical system by this invention.

[FIGURE 5]

(a) is the principal-part sectional view of the fourth example of the optical-path conversion optical system by this invention, (b) is the sectional view showing that modification.

[FIGURE 6]

It is the schematic sectional view showing an example which utilised the first example of this invention for the electron camera.

[FIGURE 7]

It is the principal-part sectional view showing the example of representation of the visual-field conversion optical system of an perspective 70 conventional degrees.

[FIGURE 8]

It is the principal-part sectional view showing the example of representation of the visual-field conversion optical system of a side view 90 conventional degrees.

[FIGURE 9]

It is the conventional principal-part sectional view showing the example of representation of a rear viewing visual-field conversion optical system 110 degrees.

[EXPLANATION OF DRAWING]

1 First Optical Member

1 a The first reflecting surface

1 b The second reflecting surface 1c Spherical surface

1d Bonding plane

2 Second Optical Member 2a Optical guide surface

2b The third reflecting surface

2c The fourth reflecting surface

2d Radiation surface

3 Third Optical Member

SH Shading board

SH1 Aperture

L Concave lens

L1 Objective lens

CG Cover glass

P Pipe

T Stainless-steel tube

1 G Light guide

O Injection optical axis

SP Spacer

R, R1 , R2 Reflecting surface

F Finder

OP Optical-path conversion optical system

IS Image sensor

Claims

[CLAIMS] [CLAIM 1]

An optical-path conversion optical system contained in the long and slender housing and comprising the first optical member provided with the first reflecting surface which bends downward the optical axis along the longitudinal direction of the housing when an optical path is conversely followed toward an incidence side from an injection side, and the second reflecting surface which bends the optical axis bent by the first reflecting surface to the front upper part, and the second optical member contained in the housing and adjacently arranged ahead of the first optical member and comprising a third reflecting surface bending downward the optical axis bent by the second reflecting surface, and the fourth reflecting surface bending the optical axis bent by the third reflecting surface to the predetermined upper part.

[CLAIM 2]

An optical-path conversion optical system described in Claim 1 wherein further comprising the third optical member contained in the housing and arranged on the upper part of the second optical member.

[CLAIM 3]

An optical-path conversion optical system described in Claim 1 wherein the second optical member and the third optical member are arranged small air spaces.