JP3559341B2 - Stereoscopic endoscope - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a stereoscopic endoscope for observing and photographing an object three-dimensionally.
[0002]
[Prior art]
The stereoscopic endoscope has an objective lens system that forms an object image, a primary optical system that includes a relay lens system that transmits the image, and a pupil dividing unit that divides the image transmitted by the primary optical system into left and right, Equipped with a secondary optical system that observes or captures the two divided images, respectively, for medical use for observing a site in a body cavity, or industrial use for observing the inside of a machine such as an engine. Used. This type of stereoscopic endoscope is disclosed in, for example, Japanese Patent Application Laid-Open No. 6-194581.
[0003]
Conventional stereoscopic endoscopes use a reflection optical element such as a roof mirror or a reflecting prism as a pupil splitting unit, and each split light beam is reflected in a direction perpendicularly away from the optical axis of the primary optical system. You. The secondary optical system is provided with a pair of reflecting surfaces for reflecting the light beam reflected by the pupil dividing means again and directing it in the same direction.
[0004]
[Problems to be solved by the invention]
However, in a conventional stereoscopic endoscope, a pupil is divided by using a reflecting surface, and as described above, the separated luminous flux is directed perpendicular to the optical axis of the primary optical system and away from each other. Therefore, there is a problem that a space for disposing the secondary optical system for receiving the separated light beam becomes large.
[0005]
[Object of the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the related art, and provides a stereoscopic endoscope that can reduce the spread between optical paths after division and reduce the space for disposing a secondary optical system. With the goal.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a stereoscopic endoscope according to the present invention is arranged at a pupil position of a primary optical system having an objective lens system and a relay lens system arranged in order from the object side, and a pupil position of the primary optical system. A pupil splitting prism that splits the light beam in the pupil into two regions so that the object can be observed from different directions, and refracts the split light beam in different directions; and a pair of light beams that capture the light beam split by the pupil splitting prism. And a secondary optical system.
[0007]
【Example】
Hereinafter, embodiments of the stereoscopic endoscope according to the present invention will be described.
[0008]
Embodiment 1
As shown in FIG. 1, a stereoscopic endoscope according to a first embodiment includes a tubular insertion unit 1 inserted into a narrow space such as a body cavity, and an observation unit connected to a proximal end of the insertion unit 1. Unit 2.
[0009]
Inside the insertion section 1, a first relay including an objective lens system 11 configured of three groups and four lenses for forming an image of an object, and a plurality of lens systems for transmitting an image formed by the objective lens system 11 A lens system 12 and a second relay lens system 13 forming an exit pupil are arranged in this order from the object side, and these lens systems constitute a primary optical system 10.
[0010]
In the observation unit 2, a pair of wedge-shaped pupil splitting prisms 70 and 71 for dividing the light beam in the pupil into two regions and refracting the split light beam in different directions so that the object can be observed from different directions. Are arranged so as to coincide with the pupil position of the primary optical system 10, and a pair of secondary optical systems 30a and 30b that receive the light beams split by these pupil splitting prisms 70 and 71 are arranged.
[0011]
The pupil splitting prism 70 is configured as an achromatic prism in which two prisms 70a and 70b having different dispersion values are bonded together to reduce chromatic aberration. Similarly, the other pupil splitting prism 71 is also configured as an achromatic prism in which two prisms 71a and 71b are bonded.
[0012]
The conditions for achromatism are given by the following equations, where the apex angles of the respective prisms are A1 and A2, the dispersion values are V1 and V2, the refractive indices are N1 and N2, and the combined deflection angle of both prisms is Dt.
[0013]
(Equation 1)
A1 = Dt · V1 / ((N1-1) · (V1-V2))
A2 = Dt · V2 / ((N2-1) · (V2-V1))
[0014]
The pupil splitting prisms 70 and 71 divide the light beam that has reached the pupil of the primary optical system 10 into two components, left and right, so that stereoscopic viewing is possible, and separate each component from the optical axis Ax1 of the primary optical system 10. The wedges are arranged symmetrically with respect to the optical axis Ax1 with the tip side of the wedge facing the optical axis Ax1 of the primary optical system 10 so as to be refracted in the direction.
[0015]
Each of the secondary optical systems 30a and 30b includes an imaging lens system 32a and 32b, and image receiving elements 34a and 34b. Each light beam split into two regions by the pupil splitting prisms 70 and 71 passes through the imaging lens systems 32a and 32b, respectively, and forms an image on the imaging devices 34a and 34b such as a CCD. The imaging lens systems 32a and 32b are arranged obliquely with respect to the optical axis Ax1 of the primary optical system 10 so that their optical axes are parallel to the optical paths refracted by the pupil splitting prisms 70 and 71. The imaging devices 34a and 34b are arranged so that their light receiving surfaces are perpendicular to the optical axes of the imaging lens systems 32a and 32b.
[0016]
In order to enable stereoscopic viewing, it is necessary to observe one object from different directions, and for that purpose, it is necessary to guide light beams passing through different regions in the pupil to the left and right secondary optical systems. . Therefore, the pupil splitting prisms 70 and 71 are provided at the pupil position of the primary optical system 10 symmetrically with respect to the optical axis. Accordingly, the central axes of the light beams incident on the secondary optical systems 30a and 30b form a predetermined interval on the pupil, and a parallax corresponding to the interval can be provided between images captured by the respective image sensors. . The central axis of the light beam incident on the secondary optical system is defined as an axis passing through the position of the center of gravity of the cross section of the split light beam.
[0017]
Therefore, a stereoscopic image can be obtained by displaying images captured by the imaging devices 34a and 34b on separate displays, and observing each display separately with the right eye and the left eye. Further, an image captured by the image capturing means can be recorded by a VTR or the like while maintaining stereoscopic information.
[0018]
When the optical path is deflected by using the prism as described above, trapezoidal distortion occurs in an image formed on the image sensor. In this embodiment, trapezoidal distortion is corrected by performing image processing such as affine transformation on an image captured by an image sensor.
[0019]
According to the first embodiment, by using the prism as the pupil splitting element, the angle formed by the split light beams can be set to the minimum necessary, and the arrangement space of the secondary optical system can be suppressed smaller than before. . In particular, when an image is taken using an image sensor as in the first embodiment, unlike the case of direct observation with the naked eye, it is not necessary to adjust the axial interval of the secondary optical system to the interpupillary distance. The size of the observation unit 2 can be minimized in accordance with the size of the imaging unit and the size of the imaging device. In addition, since the optical axes of the secondary optical system do not need to be parallel, the configuration of the secondary optical system can be simplified to only the imaging lens and the imaging device.
[0020]
Embodiment 2
FIG. 2 is an overall explanatory diagram illustrating the stereoscopic endoscope according to the second embodiment. In the second embodiment, the pupil splitting prisms 70 and 71 are separated from each other so as to have an interval at the center, and the rectangular light shielding plate 22 is disposed so as to cover the interval. Other configurations are the same as those of the first embodiment. The embodiment in which the light-shielding plate 22 is arranged to shield the central part of the pupil, and the interval between the central axes of the light beams incident on the secondary optical systems 30a and 30b (interval of the incident axis) is not provided with the light-shielding plate 22. The value is set to be larger than in the case of 1.
[0021]
When the central axis interval of the light beam incident on the secondary optical system increases, the amount of light incident on the secondary optical system decreases.However, if the distance from the objective lens system to the object to be observed is the same, the expected angle with respect to the object is reduced. Since it becomes large, a three-dimensional appearance (degree of lifting) can be increased. Therefore, even when the object distance is longer, a three-dimensional effect can be obtained.
[0022]
As shown in FIG. 3, even when the pupil splitting prisms 70 and 71 are arranged in contact with each other in the same manner as in the first embodiment, a light shielding plate is provided on the side of the relay lens system 13 so as to cover the tip portions of the wedges of both prisms. By providing 22, it is possible to obtain the effect of increasing the interval between the incident axes, as in the second embodiment. In the case of the example of FIG. 3, if the width of the light-shielding plate 22 can be changed, the stereoscopic effect can be changed during observation.
[0023]
Also in the case of the second embodiment, since trapezoidal distortion occurs in the image on the image sensor, image processing such as affine transformation is required when displaying this.
[0024]
Embodiment 3
FIG. 4 is an overall explanatory diagram showing Embodiment 3 of the stereoscopic endoscope of the present invention. In this embodiment, each of the secondary optical systems 30a and 30b is configured to enable observation with the naked eye. Since the configuration of the insertion section 1 is the same as in the above embodiment, only the configuration of the observation section 2 will be described.
[0025]
A pair of pupil splitting prisms 70 and 71 as pupil splitting means are arranged in the observation unit 2 and a pair of secondary optical systems 30a and 30a receive light beams split by the pupil splitting prisms 70 and 71. 30b are arranged. Each of the secondary optical systems 30a and 30b includes optical path deflecting prisms 72a and 72b, imaging lens systems 32a and 32b, and eyepiece lens systems 33a and 33b.
[0026]
The light flux refracted by the pupil splitting prisms 70 and 71 and refracted in a direction away from the optical axis Ax1 is refracted by the optical path deflecting prisms 72a and 72b in a direction parallel to the optical axis Ax1 of the primary optical system 10 to form an imaging lens system. The light enters the left and right eyes of the observer via the eyepiece systems 33a and 33b, and the observer can observe the object three-dimensionally.
[0027]
The pupil splitting prisms 70 and 71 and the optical path deflecting prisms 72a and 72b are formed of the same material and have the same apex angle, and the chromatic aberration generated on one side can be canceled out on the other. It is not necessary to bond them for correction.
[0028]
When the prisms are used in combination in this manner, trapezoidal distortion does not occur and the optical axis of the secondary optical system can be made parallel, so that it can be directly observed with the naked eye.
[0029]
Also in the configuration of the third embodiment, a stereoscopic image is converted into a video signal as in the first and second embodiments by providing an image sensor at the image plane position of the imaging lens systems 32a and 32b instead of the eyepiece lens systems 33a and 33b. Can be taken out. In this case, image processing such as affine transformation for correcting trapezoidal distortion is unnecessary.
[0030]
Embodiment 4
FIG. 5 is an optical path diagram of a main part of a stereoscopic endoscope according to a fourth embodiment of the present invention. The pupil splitting prism 73 is a roof-type prism whose thickness in the optical axis direction decreases toward both ends with the optical axis Ax1 of the primary optical system as a center. The light beams incident on the incident end faces 73a and 73b are deflected toward the opposite sides from the incident side with the optical axis as a boundary, and the secondary optical systems 30a and 30a located on opposite sides of the respective surfaces with respect to the optical axis Ax1. 30b.
[0031]
The light beams incident on the secondary optical systems 30a and 30b are imaged on the imaging devices 34a and 34b by the imaging lenses 32a and 32b, respectively. In the fourth embodiment, since the image on the image sensor includes trapezoidal distortion, image processing such as affine transformation is required to correct this.
[0032]
FIG. 6 shows a modification of the fourth embodiment. In this example, a single optical path deflection prism 74 is disposed between the roof prism 73 and the imaging lenses 32a and 32b. The light beam incident on one incident end face 73a of the pupil splitting prism 23 is emitted from the exit end face 74a of the optical path deflecting prism 74 and is incident on the imaging lens 32a, and the light beam incident on the other incident end face 73b is emitted from the other The light exits from the end face 74b and enters the imaging lens 32b.
[0033]
Also in this example, the apex angle of the pupil splitting prism 73 and the apex angle of the optical path deflection prism 74 are set to be equal, and since each prism is formed of the same material, the optical axis of the secondary optical system is set to be parallel. In addition, chromatic aberration and trapezoidal distortion can be prevented.
[0034]
Embodiment 5
FIG. 7 is an explanatory diagram of an observation unit showing a fifth embodiment of the stereoscopic endoscope according to the present invention. In the stereoscopic configuration endoscope of the fifth embodiment, a rigid microscope for monocular vision is configured only by the insertion section 1 provided with the primary optical system 10, and the rigid mirror has a pupil dividing means, a secondary optical system, Is attached as an adapter for binocular vision. The optical configuration is the same as that of the first embodiment shown in FIG.
[0035]
A brim-shaped hood 14 that comes into contact with the periphery of the observer's eyes when observing with a single eye and blocks ambient light is attached to the base end side of the insertion section 1. The observation section 2 is fixed to the insertion section 1 via an attachment 50 attached to the hood 14.
[0036]
The attachment 50 is attached to the hood 14 from the observation unit 2 side and surrounds the hood 14 from the outside, an attachment piece 52 that comes into contact with the hood 14 from the object side and attaches to the attachment ring 51, and an attachment piece 52. And a fixing bolt 53 for fixing the fixing member 52 to the mounting ring 51.
[0037]
The mounting ring 51 includes a disk portion 51a having an opening formed in the center that contacts the hood 14, and a cylindrical portion 51b that is raised from the peripheral edge of the disk portion 51a toward the object side and surrounds the outer periphery of the hood 14. And a flange portion 51c formed from the object-side tip of the cylindrical portion toward the inner periphery. The attaching piece 52 is a small piece having an L-shaped cross section, and the hood 14 is applied to the mounting ring 51 at at least three locations in the circumferential direction.
[0038]
In addition, adjustment bolts 54 protruding toward the observation unit 2 side are fixed to three places in the circumferential direction on the outer peripheral portion of the surface of the mounting ring 51 on the observation unit 2 side. The observation section 2 has an outer flange 2b formed in a peripheral portion on the insertion section 1 side, and a through hole 2c through which the adjustment bolt 54 is inserted is formed in the outer flange 2b. The adjustment bolt 54 is fixed to the outer flange 2b by nuts 55 and 56 located on both sides of the outer flange 2b while being inserted into the through hole 2c, and the insertion portion 1 attached to the attachment 50 is attached to the observation portion 2. Fix for.
[0039]
In the fifth embodiment, the positional relationship between the attachment 50 and the observation unit 2 can be three-dimensionally adjusted by adjusting the positions of the nuts 55 and 56 screwed to the three adjustment bolts 54. it can.
[0040]
【The invention's effect】
As described above, according to the present invention, by using the refraction function of the prism to split the pupil, the spread angle of the split light beam can be made smaller than that using the reflection function. The space for disposing the next optical system can be reduced.
[Brief description of the drawings]
FIG. 1 is an overall plan view showing a first embodiment of a stereoscopic endoscope according to the present invention.
FIG. 2 is a plan view of an observation unit showing a stereoscopic endoscope according to a second embodiment of the present invention;
FIG. 3 is an optical path diagram of a main part showing a modification of the second embodiment.
FIG. 4 is an overall plan view showing Embodiment 3 of the stereoscopic endoscope of the present invention.
FIG. 5 is an optical path diagram of a main part of a stereoscopic endoscope according to a fourth embodiment of the present invention.
FIG. 6 is an optical path diagram of a main part showing a modification of the fourth embodiment.
FIG. 7 is a plan view of an observation unit showing a fifth embodiment of the stereoscopic endoscope according to the present invention;
[Explanation of symbols]
Reference Signs List 1 Insertion unit 2 Observation unit 10 Primary optical system 11 Objective lens system 12 First relay lens system 13 Second relay lens system 14 Hoods 30a, 30b Secondary optical systems 32a, 32b Imaging lens systems 34a, 34b Image sensor 70 , 71 Pupil splitting prism

Claims (10)

A primary optical system having an objective lens system and a relay lens system arranged in order from the object side,
A pupil splitting prism arranged at a pupil position of the primary optical system, splitting a light beam in the pupil into two regions so that the object can be observed from different directions, and refracting the split light beam in different directions;
A stereoscopic endoscope comprising: a pair of secondary optical systems for receiving the light beam split by the pupil splitting prism. The stereoscopic endoscope according to claim 1, wherein each of the pupil splitting prisms is configured by an achromatic prism that reduces chromatic aberration caused by the prism. The stereoscopic endoscope according to claim 1, wherein the pupil splitting prism includes a pair of wedge-shaped prisms arranged symmetrically about an optical axis of the primary optical system. 4. The wedge-shaped prism according to claim 3, wherein the wedge-shaped prism is disposed such that a tip end of the wedge is directed toward the optical axis so as to refract the split light beam in a direction away from an optical axis of the primary optical system. 5. A stereoscopic endoscope as described. The three-dimensional prism according to claim 1, wherein the pupil splitting prism is a roof-type prism whose thickness in the optical axis direction decreases with distance from the center with respect to the optical axis of the primary optical system. Endoscope. The stereoscopic vision according to claim 1, wherein the secondary optical system includes an optical path deflection prism that refracts a light beam refracted by the pupil splitting prism in a direction parallel to an optical axis of the primary optical system. Endoscope. The stereoscopic endoscope according to claim 6, wherein the optical path deflection prism has the same apex angle and material as the pupil division prism. The stereoscopic endoscope according to claim 6, wherein the optical path deflecting prism is disposed one by one in each of the secondary optical systems. 2. The stereoscopic vision according to claim 1, wherein the secondary optical system includes an imaging lens system that forms an image of each of the light beams split by the splitting prism, and an image sensor that captures the image. 3. Endoscope. 2. The secondary optical system according to claim 1, further comprising an imaging lens system configured to form an image of each of the light beams split by the splitting prism, and an eyepiece lens system configured to guide the image to an observer's eye. 3. A stereoscopic endoscope according to item 1.

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