JPH0735989A - Stereoscopic viewing endoscope - Google Patents

Abstract

PURPOSE:To provide a stereoscopic viewing endoscope capable of improving resolution in a vertical direction and making an operation part compact. CONSTITUTION:An image is formed on a CCD 2 by a pair of objective optical systems 5a and 5b relay optical systems 6a and 6b which are arranged to be separated in a horizontal direction, and anamorphic image formation lenses 33a and 33b which reduces the image formation magnification of an optical image transmitted by the relay optical systems 6a and 6b is made smaller in the horizontal direction than in a vertical direction; and right and left images formed to be long lengthwise on the CCD 2 and photoelectrically converted are elongated in the horizontal direction by a signal processor 32 so as to alternately fully display the right and the left images on a TV monitor 10, thereby realizing the stereoscopic vision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereoscopic endoscope capable of stereoscopic observation.

[0002]

2. Description of the Related Art Most endoscopes view an object to be examined, for example, the inside of a body cavity, as a plane without a sense of perspective. However, it has been difficult for a conventional endoscope to observe minute irregularities on the inner wall surface of a body cavity, which are very important as a diagnostic index. In order to deal with this, a stereoscopic endoscope has been proposed.

For example, Japanese Unexamined Patent Publication No. 57-69839 discloses a pair of two image guides each having an objective lens at one end and an eyepiece lens at the other end. In this stereoscopic endoscope, the two image guides as a pair are installed in the endoscope insertion portion so that the vergence angle between the optical axes of the pair of objective lenses becomes a stereoscopically viewable angle. The inside of the body cavity can be observed three-dimensionally.

The above-mentioned conventional stereoscopic endoscope is an example applied to a flexible endoscope, but as a stereoscopic rigid endoscope, two relay optical systems are arranged in parallel and two relay optical systems are arranged. There is a system that enables a stereoscopic observation by capturing an optical image obtained by a system with a CCD or the like. US Pat. No. 4,924,8
Japanese Patent Laid-Open No. 35-35 discloses that two light transmission means and two shutters are provided, and two light images obtained by these light transmission means are alternately shielded by a shutter to enable stereoscopic observation. There is.

As shown in FIG. 12, a first conventional rigid stereoscopic endoscope 1 is composed of a pair of optical systems and a pair of CCDs 2a and 2b as image pickup devices. The insertion portion 3 of the rigid stereoscopic endoscope 1 is provided with a pair of objective optical systems 5a and 5b for forming an image of the subject 4 in an observation window at the tip thereof. The pair of objective optical systems 5a and 5b are provided, for example, at intervals d in the left-right direction (horizontal direction) so as to obtain parallax that allows stereoscopic viewing.

Behind the objective optical systems 5a and 5b, relay optical systems 6a and 6 for transmitting left and right subject images, respectively.
b is arranged. A shield plate (not shown) is arranged between the relay optical systems 6a and 6b.

Behind the relay optical systems 6a and 6b, crank type relay optical systems 7a and 7b for transmitting the left and right subject images by changing their optical paths, respectively, and the CC
Image forming lenses 8a and 8b for forming the left and right images are arranged on D2a and 2b, respectively.

The left and right subject images picked up by the CCDs 2a and 2b are converted into electrical signals, processed by the signal processing device 9, and displayed on the TV monitor 10. Further, low-pass filters 11a and 11b made of crystal or the like are arranged immediately in front of the CCDs 2a and 2b to prevent generation of false signals (moire) between the subject 4 and the CCDs 2a and 2b.

As a method of observing a stereoscopic image, a left image and a right image are alternately switched and displayed on the TV monitor 10 at high speed, and a viewer wears special glasses to view the left image with the left eye and the right image with the right eye. There is a way to get a three-dimensional effect.

In recent years, two small image display devices such as a liquid crystal display are used to display a left image on one side and a right image on the other side, and observe each with a left eye and a right eye to obtain a stereoscopic effect. Methods have also been proposed. In order to obtain a normal stereoscopic effect in any of the display systems, it is necessary to focus on the center point of the left and right visual fields (the point where the optical axes of the left and right optical systems intersect). .

In such a rigid stereoscopic endoscope 1, (1) two CCDs 2a and 2b are required, which is expensive and the distance L between the optical paths incident on each CCD 2a and 2b.
Needs to be set to a value equal to or larger than the value at which the two CCDs 2a and 2b can be arranged, which increases the size of the operation unit at hand. (2) Since each optical component is completely independent, for example, a low-pass filter such as a crystal arranged immediately before each CCD 2a (or 2b) is required twice, which is expensive.

Therefore, in the conventional example shown in FIG. 13, the common CCD 2 is used to solve the above-mentioned drawback. A second conventional rigid stereoscopic endoscope 21 shown in FIG.
In the rigid stereoscopic endoscope 1 of FIG. 12, the relay optical systems 6a and 6b are common, and the relay optical systems 6a and 6b are common.
The imaging lenses 23a and 23b, which are housed in the operation unit 22 and form left and right images, are disposed behind the common CC.
Left and right images are formed on D2.

The left and right subject images picked up by the CCD 2 are converted into electric signals, processed by the signal processing device 24, and displayed on the TV monitor 10. As described above, in the second conventional example, the single CCD 2 eliminates the need for the crank-type relay optical system, and
Only one low-pass filter 11 arranged just before CD2 is required. Further, the operation unit 22 can be downsized.

[0014]

FIG. 14 is a view of the CCD 2 viewed from the optical axis direction. At this time, in the second conventional example, as shown in FIG. In order to image the field masks 24a and 24b of b so that they do not overlap with each other, it is inevitable that the field masks 24a and 24b are imaged on the vertical side of the CCD 2 to be considerably small.

When such a small image is photoelectrically converted, the number of pixels contained in the field masks 24a and 24b is reduced, so that the resolution of the image is lowered. The CCD 2 in FIG. 14 is shown in the case of the high-definition specification with an aspect ratio of 16: 9, but even with this, it is impossible to make the TV monitor 10 full screen.

It is possible to make a full screen by using a special image pickup device having a larger aspect ratio.
If the light-receiving surface becomes long, the effect of downsizing the operating portion becomes insufficient.

As described above, it is difficult for the conventional configuration to achieve both miniaturization of the operating portion and maintenance of resolution.

The present invention has been made in view of the above points, and an object of the present invention is to provide a stereoscopic endoscope in which the resolution in the vertical direction can be improved and the operating portion on the near side can be made compact.

[0019]

[Means and Action for Solving the Problems] An image forming optical system for forming a pair of object images having a parallax in the horizontal direction for stereoscopic vision, and an image pickup device for photoelectrically converting the formed optical image. In the stereoscopic endoscope having, by forming an anamorphic optical element for making the horizontal image forming magnification smaller than the vertical image forming magnification in the image forming optical system, an image is formed on the image pickup element. It is possible to increase the vertical resolution by increasing the number of pixels in the vertical direction used to photoelectrically convert an optical image, and at the same time, the hand-side operation unit side can be downsized and the signal processing system performs expansion processing. This makes it possible to display a full-resolution endoscopic image with a high resolution.

[0020]

Embodiments of the present invention will be specifically described below with reference to the drawings. 1 to 6 relate to a first embodiment of the present invention, FIG. 1 shows a rigid stereoscopic endoscope according to the first embodiment of the present invention, and FIG. 2 shows an anamorphic imaging lens. 3 shows a field mask and a field mask image, and FIG. 4 shows a CCD.
FIG. 5 shows an image formed on the TV monitor, FIG. 5 shows an image displayed on the TV monitor, and FIG. 6 shows a configuration of the signal processing device.

The stereoscopic endoscope device 30 shown in FIG. 1 is a rigid stereoscopic endoscope 31 of the first embodiment, and a signal processing device 3 for performing signal processing on the CCD 2 of the rigid stereoscopic endoscope 31.
2 and a TV monitor 1 for displaying the signal-processed video signal
0, and a light source device (not shown) that supplies illumination light to a light guide (not shown) of the rigid stereoscopic endoscope 31.

The rigid stereoscopic endoscope 31 of the first embodiment is shown in FIG.
In the rigid stereoscopic endoscope 21 of No. 3, the imaging lens 23
The anamorphic imaging lenses 33a and 33b as shown in FIG. 2 are used as a and 23b. It should be noted that FIG. 1 is a view of a pair of objective optical systems 5a, 5b, etc., which are arranged in the left-right direction (horizontal direction) at regular intervals (so as to obtain a parallax capable of stereoscopic vision) as viewed from the vertical direction. As shown, the plane of FIG. 1 is parallel to the horizontal direction.

FIG. 2 (a) is a view as seen from the vertical direction of the paper surface in FIG. 1, and FIG. 2 (b) is a view as seen from below in the paper surface in FIG. Reference numeral 3 in FIGS. 2A and 2B
The final relay image shown by 4 is the relay optical system 6a, 6b in FIG.
This is the image of the subject transmitted by.

The final relay image 34 is divided into images 35A and 35B having different horizontal and vertical image forming magnifications (magnifications of formed images) on the CCD image pickup surface 2A by the anamorphic image forming lens 33a. Become. As described above, the circular visual field mask 3 has different imaging magnifications in the horizontal and vertical directions.
The case of 6 will be further described.

A circular visual field mask 36 (see FIG. 3A) is arranged at the position of the final relay image 34, and the CCD image pickup surface 2A at the image forming position with respect to the mask 35.
Anamorphic image forming lenses 33a and 33b are set so that the image forming magnifications in the horizontal direction and the vertical direction are different from each other.

More specifically, as shown in FIG.
Mask image 36A that is vertically formed on the CCD image pickup surface 2A
As described above, the image forming magnification in the horizontal direction is set to be smaller than the image forming magnification in the vertical direction. 2 (a),
Also in (b), the images 35A and 35B on the CCD image pickup surface 2A with respect to the final relay image 34 have a relationship of the length of the image 35A <the length of the image 35B. That is, the anamorphic imaging lenses 33a and 33b perform a process of optically compressing an image in the left-right direction (relative to the up-down direction).

As in the case of FIG. 13, in the case of the CCD 2 having the aspect ratio of 16: 9 of the high definition, the circular visual field masks 36, 36 arranged at the positions of the final relay images 34, 34 are the CCD image pickup surface 2A. Then, as shown in FIG. 4, a mask image 36A which is vertically long and is formed so as to be separated from each other in the left and right directions is
Can be 36A.

When the CCD 2 having an aspect ratio of 16: 9 has an equivalent aspect ratio of 24: 9 (that is, 8: 3), full display can be performed on the TV monitor 10 having an aspect ratio of 4: 3.

In this embodiment, the anamorphic image forming lenses 33a and 33b are used to optically compress the image in the horizontal direction (relative to the vertical direction) to 2/3, and the CCD 2 captures the image. The aspect ratio of surface 2A is equivalently 2
It has a function equivalent to that of a CCD having an aspect ratio of 4: 9.

The image on the image pickup surface 2A is photoelectrically converted into an image signal by the CCD 2, and the image signal is expanded in the horizontal direction by a signal processing device 32 described later to 3/2 to obtain the original aspect ratio. After the returning process is performed, the mask diameter can be displayed on a substantially full screen on the TV monitor 10 that stereoscopically views as shown in FIG. Reference numeral 37 of FIG. 5 is a mask image displayed.

FIG. 6 shows the configuration of the signal processing device 32 which performs the signal processing for displaying in this way. Imaging lens 33
The images formed by a and 33b are photoelectrically converted by the CCD 2, read by application of a drive signal from the CCD driver 41, amplified by the preamplifier 42, and γ
The correction circuit 43 performs gamma correction, and the white balance circuit 44 performs white balance.

The output signal of the white balance circuit 44 is converted into a digital signal by an A / D converter (not shown) and then divided by the first changeover switch 45 into image information of the optical path a and the optical path b. Image memory 46a
Is stored in the image memory 46b on the optical path b side. The first changeover switch 45 is changed over by a switching signal from the timing generator 47, for example, in half of the horizontal read period in which the CCD 2 is read horizontally in a line.

The image memories 46a and 46b respectively store the image information 48 as shown in FIG. 6B obtained by horizontally dividing the image of FIG. 4 into two equal parts. Memory 46
The image information stored in a and 46b are read out, and the image information selected by the second changeover switch 49 is input to the horizontal expansion circuit 50.

The second selector switch 49 is switched by the timing generator 47 at regular intervals.
The image input to the horizontal direction expansion circuit 50 is expanded in the horizontal direction (horizontal direction). This expansion processing is processing for returning an optically compressed image. Therefore, when the image is expanded by the horizontal expansion circuit 50, the image of FIG. 6B becomes the image information 51 shown in FIG. 6C, for example.

That is, the image of FIG. 6B obtained by compressing the circular visual field mask image in the horizontal direction is subjected to the expansion processing to obtain the image of FIG.
As shown in (c), the circular visual field mask image is restored. The digital image expanded by the horizontal expansion circuit 50 is converted into an analog signal by a D / A converter (not shown) and is output to the TV monitor 10 as a standard video signal together with a synchronization signal (not shown). The image on the b side is displayed alternately in, for example, one field period of 1/60 sec or one frame period of 1/30 sec.

In this embodiment, the TV monitor 10 is formed by, for example, a stereoscopic monitor by switching the polarization direction using a liquid crystal polarization plate 52, and an image displayed on the display surface of the TV monitor unit 53 is a liquid crystal polarization liquid crystal display facing the display surface. Observed through plate 52.

The liquid crystal polarizing plate 52 is applied with a pulsed drive signal which becomes "H" and "L" in one field or one frame period from the polarizing plate driver 54 in synchronization with the alternately displayed images. The liquid crystal polarization plate 52 has a vertical polarization direction when an image on the optical path a side, that is, the right image is displayed, and a horizontal polarization direction when an image on the optical path a side, that is, the left image is displayed. become.

The observer uses polarizing glasses 55 having polarizing plates set to have a vertical polarization direction on the right eye side and a horizontal polarization direction on the left eye side, so that the right image is viewed by the right eye. , The image can be observed independently by the left eye.

According to this embodiment, the common CCD 2 is formed by using the anamorphic image forming lenses 33a and 33b.
The image is formed such that the image is short in the horizontal direction and long in the vertical direction, and the CCD 2 having an aspect having an imaging area for two display surfaces of the TV monitor 10 is equivalently realized.

Therefore, the right and left images picked up by the CCD 2 can be fully displayed as they are by passing through the horizontal expansion circuit 50. Therefore, for example, in FIG.
Even if the right and left images are imaged by using the full vertical imaging frame as shown in FIG. 5, the captured right or left image can be displayed as it is on the display surface of the TV monitor 10 as shown in FIG. Therefore, it is possible to prevent the resolution from decreasing in the vertical direction.

Further, since the rigid stereoscopic endoscope 31 itself has a construction in which the imaging lenses 23a and 23b in the second conventional example are replaced with anamorphic imaging lenses 33a and 33b, the operating portion 22 is used. Can be miniaturized and can be manufactured with almost no increase in manufacturing cost.

In the first embodiment, the entire image of the field mask 36 is C by the anamorphic image forming lenses 33a and 33b.
Although the case where the image can be formed on the CD 2 is shown, it is also possible to form the image on the CCD 2 not on the entire image of the visual field mask 36 but on a portion except for both ends in the vertical direction as shown in FIG. 7, for example.

When an image is formed on the image pickup surface 2A of the CCD 2 as shown in FIG. 7, an image of a circular area in which both ends in the vertical direction are cut off is displayed on the display surface of the TV monitor 10 as shown in FIG. Will be done. In this case, a part of the image is kicked, but the number of pixels included in the mask image increases, so that an image with better resolution can be observed.

FIG. 9 shows a stereoscopic endoscope apparatus 60 according to a second embodiment of the present invention. This stereoscopic endoscope apparatus 60 is a second endoscope apparatus.
The rigid stereoscopic endoscope 61 and the rigid stereoscopic endoscope 6 of the embodiment.
1, a signal processing device 62 that performs signal processing for 1, a TV monitor 10, and a light source device (not shown).

This embodiment is similar to the first embodiment, for example, C
An anamorphic optical system is arranged in front of the CD2, but in this embodiment, one anamorphic image forming lens 63 is used in common.

Although not described in the first embodiment, the subject 4
When stereoscopically viewing, the stereoscopic effect changes depending on the size of the convergence angles of the left and right observation optical axes, so it is important to determine the size of the convergence angle. As in this embodiment, T
In the device for observing the image displayed on the V monitor 10, the final stereoscopic effect is determined by the positional relationship between the image displayed on the monitor and the eyes of the observer, and the left and right images displayed on the monitor are determined. The positional relationship changes depending on the convergence angle α at the subject position. When focus adjustment is performed, for example, when the object distance becomes long, the convergence angle at the subject position becomes small (α ′) as shown in FIG. The shift in the field of view changes the stereoscopic effect. As the stereoscopic effect changes as the focus changes, it is hard to see, so in order to prevent the apparent stereoscopic effect from changing on the monitor screen, use the focus adjustment in conjunction with
It is necessary to move the left and right image positions on the monitor screen.

Therefore, a movement amount detecting means 64 for detecting the displacement amount (movement amount) of the imaging lens 63 at the time of focusing adjustment is provided.

A position signal corresponding to the moving amount of the imaging lens 63 detected by the moving amount detecting means 64 is input to the signal processing device 62, and the distance to the person 4 is calculated by this position signal and calculated. The distance s between the optical field a on the CCD 2 surface and the visual field center of the optical path b necessary to keep the angle α constant according to the distance is calculated, and the optical path a and the optical path b on the CCD 2 surface where the image is actually formed are calculated. The signal processing device 62 corrects so that the distance between the visual field centers becomes equal to this distance s.

This correction can be performed by adjusting the timing of reading the right image and the left image stored in the image memories 46a and 46b in the horizontal direction, or by performing a correction process such as shifting the delay time through a tapped delay line. it can. This signal processing device 62 has a configuration in which a correction processing function is added to the signal processing device 32 of the first embodiment. Further, as can be seen from a comparison between FIG. 1 and FIG. 9, in FIG. 9, the image forming position on the CCD 2 is switched to the left and right as compared with the case of FIG. 1, so that the switch 45 or 49 in FIG. .

In addition to the functions and effects of the first embodiment, this embodiment can maintain a constant stereoscopic effect even if the distance to the subject 4 changes.

Further, the anamorphic optical element is not limited to being provided at the position where the image forming optical system is arranged, and the objective optical systems 5a and 5b and the relay optical systems 6a and 6b are not limited thereto.
Can be used for, and the effect in that case is almost the same. FIG. 10 shows a rigid stereoscopic endoscope 71 according to the third embodiment of the present invention.

The rigid stereoscopic endoscope 71 according to the third embodiment.
Uses the pupil division type.

That is, in this embodiment, the objective optical system 5,
The relay optical system 6 has only one set, and realizes stereoscopic vision using the pupil division prism 72. That is, the exit light from the relay optical system 6 is split by the pupil splitting prism 72 into two light beams centered on a position away from the common optical axis of the objective optical system 5 and the relay optical system 6, and each light beam has a CCD 2 The subject image is formed on the top.

Also in this case, the anamorphic optical element may be placed at any position such as the objective optical system 5, the relay optical system 6 or the imaging lens 23. Of course, the reflecting surface and the refracting surface of the pupil division prism 72 may be curved surfaces, and these surfaces may have the function of the anamorphic optical system. In FIG. 10, an anamorphic imaging lens 73 is used as an example.

In an image pickup apparatus using a solid-state image pickup device such as a CCD, an optical system requires an optical low-pass filter using a birefringent plate, a diffraction grating, a phase grating, and the like.

In the case of the third embodiment, since the left and right optical systems are common, this low-pass filter can also be common. In FIG. 10, a desired effect is obtained by arranging the birefringent plate at the first and second image forming positions (not shown). Even if a low-pass filter including a diffraction grating, a phase grating, a mountain prism, etc. is arranged at the first and second pupil positions, the desired effect can be obtained.

FIG. 11 shows a rigid stereoscopic endoscope 81 according to the fourth embodiment of the present invention. In this embodiment, for example, the third embodiment has a structure in which the rigid stereoscopic endoscope body 82 and the TV camera section 83 can be separated and attached.

The rigid stereoscopic endoscope body 82 is the objective optical system 5
A sapphire glass 84 is attached in front of the first lens of FIG. 1 to protect the observation window, and a sapphire glass 85 is attached to the second image forming position by the relay optical system 6.
The eyepiece window is protected. A screw portion is provided on the outer peripheral surface of the eyepiece window so that the TV camera portion 83 can be detachably attached.

Sapphire glass 8 as shown in FIG.
When protected with 4, 85, since the sapphire glass 84, 85 has very good chemical resistance, the stereoscopic endoscope body 82 to be inserted into the body cavity and the TV camera section 83 on the side of the hand operation section.
If the structure can be removed, sterilization and disinfection and cleaning functions can be improved. That is, the side of the stereoscopic endoscope main body 82, which is easily polluted, can be more reliably sterilized by an autoclave device or the like, or can be more reliably sterilized by an antiseptic solution, or washed.

Furthermore, since sapphire glass also has a birefringence as a low-pass filter, it is convenient because it can also serve as its function. Note that an optical element that is not a birefringent substance may be used instead of the sapphire glass 84 that protects the observation window. Incidentally, for example, in the first embodiment, the CCD 2 has the structure shown in FIG.
As shown in FIG. 4, the circular field mask is imaged vertically long (horizontal direction is ⅔ of vertical direction), and in this state, the number of pixels actually used in the horizontal direction is smaller than that in the vertical direction.

An anamorphic optical element which forms an image so as to expand or expand in the horizontal direction rather than that shown in FIG. 4 may be used so that pixels in the horizontal direction can be effectively used. By doing so, pixels in the horizontal direction can be effectively used, and an image with high resolution in the horizontal direction can be obtained. In this case, in the signal processing system, the magnification for expanding the image in the horizontal direction may be reduced.

That is, the invention is not limited to the anamorphic optical element having the image forming magnification (the horizontal direction is ⅔ of the vertical direction) described in the first embodiment, and if the left and right images do not overlap, A larger image magnification in the horizontal direction may be used. Further, as described below, an anamorphic optical element having a smaller horizontal image formation magnification may be used depending on the aspect ratio of the CCD.

In the first embodiment and the like, the case of the CCD 2 of the high-definition specification has been described, but C of other aspect ratios is used.
The same applies to a CD. For example, in the case of a CCD having a shorter aspect ratio in the horizontal direction, by using an anamorphic optical element such that the horizontal image forming magnification is made smaller than the vertical image forming magnification as compared with the case of the high definition specification. , A captured image that can be fully displayed on a TV monitor can be obtained.

It should be noted that different embodiments can be constructed by partially combining the above-mentioned embodiments, and these also belong to the present invention.

[0065]

As described above, according to the present invention, the resolution in the vertical direction can be improved by using the anamorphic optical element which makes the horizontal image forming magnification smaller than the vertical image forming magnification. It enables downsizing of the operation part at hand and reduction of the number of optical parts.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a rigid stereoscopic endoscope according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an anamorphic imaging lens.

FIG. 3 is an explanatory view showing a visual field mask and a visual field mask image.

FIG. 4 is an explanatory diagram showing an image formed on a CCD.

FIG. 5 is an explanatory diagram showing an image displayed on a TV monitor.

FIG. 6 is a block diagram showing a configuration of a signal processing device.

FIG. 7 is an explanatory diagram showing a visual field mask image in a modification of the first embodiment.

8 is an explanatory diagram showing an image displayed on the TV monitor in the case of FIG. 7. FIG.

FIG. 9 is a configuration diagram showing a rigid stereoscopic endoscope according to a second embodiment of the present invention.

FIG. 10 is a configuration diagram showing a rigid stereoscopic endoscope according to a third embodiment of the present invention.

FIG. 11 is a configuration diagram showing a rigid stereoscopic endoscope according to a fourth embodiment of the present invention.

FIG. 12 is a configuration diagram showing a rigid stereoscopic endoscope of a first conventional example.

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

FIG. 14 is an explanatory diagram of a CCD according to a second conventional example when viewed from the optical axis direction.

FIG. 15 is an explanatory diagram showing a state in which a visual field mask is displayed on a TV monitor.

[Explanation of symbols]

 2 ... CCD 3 ... Insertion part 4 ... Subject 5a, 5b ... Objective optical system 6a, 6b ... Relay optical system 10 ... TV monitor 11 ... Low-pass filter 22 ... Operation part 30 ... Stereoscopic endoscope device 31 ... Hard stereoscopic vision Scope 32 ... Signal processing device 33a, 33b ... Anamorphic imaging lens 46a, 46b ... Image memory 50 ... Horizontal expansion circuit

Claims (1)

[Claims] 1. A stereoscopic endoscope having an image forming optical system for forming a pair of subject images having a parallax in the horizontal direction for stereoscopic view, and an image pickup device for photoelectrically converting the formed optical image. 3. The stereoscopic endoscope according to claim 1, wherein an anamorphic optical element is provided in the image forming optical system to make the image forming magnification in the horizontal direction smaller than the image forming magnification in the vertical direction.