JPH0792552B2 - Measuring endoscope - Google Patents

Description

TECHNICAL FIELD The present invention relates to a measuring endoscope.

[Conventional technology]

In recent years, endoscopes have been widely used in the medical field and industrial field. Then, the size of the lesion is measured with an endoscope in order to diagnose the lesion that has occurred on the inner wall surface of the stomach or to examine how the lesion changes over time. Often, it is necessary to know the distance to the lesion.

Therefore, as a measuring endoscope for performing these measurements, for example, one disclosed in Japanese Patent Laid-Open No. 60-237419 has an illumination composed of a lamp 1 and a light guide 2 as shown in FIG. 12 (A). Light source 3, illumination positive lens 4, and, for example, the twelfth light source disposed between the illumination light source 3 and the illumination positive lens 4.
(B) has an index plate 5 having one index line 5a orthogonal to the optical axis, and projects the light from the illumination light source 3 and the image of the horizontal index line 5a onto the object 6, respectively. And an illumination optical system for projecting, an objective lens 7, an image guide 8, and a focus having a reference index line 9a which is disposed close to the exit end of the image guide 8 and is orthogonal to the optical axis as shown in FIG. It has a plate 9 and an eyepiece lens 10, and is provided with an observation optical system arranged in parallel with the illumination optical system with a predetermined optical axis distance (parallax) 1. In this endoscope, the projection image 5a 'of the horizontal index line 5a on the object 6 is always on the optical axis of the illumination optical system, and the reference index line 9a is always on the optical axis of the observation optical system. As shown in FIG. 12D, the distance between the horizontal index line image 5a 'and the reference index line 9a seen in the observation field of view of the eyepiece is always between the optical axes of the illumination optical system and the observation optical system. The distance is l, and the size of the object on the object 6 is measured by using this as an object, and the object distance is also obtained from the value.

[Problems to be solved by the invention]

However, in general, in an endoscope, it is difficult to make the objective lens 7 provided therein a movable portion for focusing because it is required that the tip hard portion has a small diameter and a small size. While the F number of 7 is increased to 2 to 4 to increase the depth of field, the positive lens 4 for illumination is used.
Requires high brightness, and the illumination light is first focused and then irradiated over a wide range, so the F number is as small as 1 and the depth of field is very shallow, resulting in observation in the optical axis direction. Index line image only in a very limited area
There is a problem that the image of 5a 'cannot be sharply imaged, and the size of the object and the object distance can be accurately measured only in the narrow portion of the observable range.

In view of the above problems, the present invention provides a measurement endoscope that enables accurate measurement of the size and object distance of an object in the entire observable range in the optical axis direction or in a very wide area. To aim.

[Means and Actions for Solving Problems]

In the measuring endoscope according to the present invention, a plurality of indicators whose positions in the direction along the illumination optical axis are different between the illumination light source and the illumination positive lens system or which are continuous in the direction along the illumination optical axis are arranged. Then, any one or any part of the index is sharply imaged over the entire observable range in the optical axis direction or a very wide part.

Further, in the measuring endoscope according to the present invention, an index is arranged between the illumination light source and the illumination positive lens system, and the distance between the index and the illumination positive lens system in the optical axis direction is variable. The index is sharply imaged in the entire observable range in the optical axis direction or in a very wide area.

〔Example〕

Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

FIG. 1 is a diagram showing the structure of a field sequential irradiation type color electronic endoscope for measurement as a first embodiment of the present invention, in which 11 is a rigid tip portion, 12 is a flexible portion, and 13 is a light source. It is a video circuit unit.

In the light source / video circuit section 14, 14 is a light source lamp, 15 is a condenser lens for condensing the light from the light source lamp 14 on the incident end face of a light guide described later, and 16 is an appropriate light shield as shown in FIG. R (red), G arranged on the circumference with a part
A rotary filter 17 has a green filter, a B blue filter, and an infrared filter, which can be sequentially inserted into and removed from the optical path, and a motor 17 drives the rotary filter 16. In the flexible portion 12 and the tip hard portion 11, 18 is a light guide, 19 is adhered to the emission end face of the light guide 18, and the mesh of the emission end face is on the object due to the scattering action by total internal reflection. Single fiber, which prevents it from being projected
Reference numeral 20 denotes a positive lens for illumination that once converges the light emitted from the single fiber 19 and then diverges the light to illuminate the object 21. The above-mentioned members basically constitute the illumination optical system, and the light emitted from the light source lamp 14 is sequentially passed through the filters of the rotary filter 16 by the condenser lens 15 to the incident end face of the light guide 18 as respective colored lights. Each color light that has been made incident and emitted from the light guide 18 passes through the single fiber 19 and is sequentially irradiated onto the object 21 by the positive lens 20 for illumination.

Further, 22 and 23 are infrared cut filters and visible cut filters that can be selectively inserted into and removed from the optical path between the light source lamp 14 and the condenser lens 15, respectively, and 24 is a single fiber 19 and a positive lens 20 for illumination. An index plate having a plurality of cross-shaped indexes 24a, 24b, 24c arranged between and having different positions in the optical axis direction, and the other part being formed as an infrared cut filter 24d made of a vapor deposition film or the like. However, these filters 22, 23, 24d have the transmission characteristics as shown in FIG. Therefore, when the infrared cut filter 22 is inserted in the optical path, since the light emitted from the light guide 18 is visible light and passes through the entire index plate 24, the index image is not projected on the object 21, but Instead of the visible cut filter 23
Is inserted into the optical path, the light emitted from the light guide 18 becomes infrared light and passes only the portions of the indexes 24a, 24b, 24c of the index plate 24, so that the index image is projected on the object 21. However, the positional relationship between the positive illumination lens 20 and the index plate 24 is determined so that any of the indicators 24a, 24b, 24c can be sharply imaged on the object 21 by the positive illumination lens 20. To do.

In the tip rigid portion 11, 25 is an objective lens, 26 is a diaphragm,
Reference numeral 27 denotes a solid-state image pickup element, which constitutes an image pickup optical system. In the light source / video circuit unit 13, 28 is a video circuit for converting the signal from the solid-state image pickup device 27 into an image signal in synchronization with the rotation of the rotary filter 16 and inputting it to the TV monitor 29. The reference index line on the screen of the TV monitor 29 at the position that matches the optical axis of the imaging optical system.
It is supposed to display 30. And these constitute an observation device together with the imaging optical system.

Since the first embodiment is constructed as described above, when the infrared cut filter 22 is inserted in the optical path, the object 21
Since only the visible light is radiated on the top and the index image is not projected, only the image by the visible light is displayed on the TV monitor 29, and normal observation can be performed. On the other hand, when the visible cut filter 23 is inserted in the optical path, the index image by infrared light is projected on the object 21, the index image 24a ″ is displayed on the screen of the TV monitor 29, and the reference index is displayed. The image 30 is also displayed.Therefore, if the image by the infrared light and the image by the immediately preceding visible light are superposed by the image processing by the video circuit 28, the interval between the index image 24a ″ and the reference index line 30 becomes the illumination optical. The size of the object on the object 21 can be measured as being equivalent to the distance 1 between the optical axes of the system and the image optical system.
Further, as is well known, a solid-state image pickup device in which an index image is captured depending on an object distance due to a parallax between an illumination optical system and an image pickup optical system.
Since the position on 27 changes, the distance between this position and the optical axis of the imaging optical system can be detected by image processing, and the object distance can be obtained from the value.

By the way, as pointed out in the conventional example, when there is only one index at the position along the illumination optical axis, the index image is sharply formed only in a very limited part of the observable range in the optical axis direction. There is a drawback that an image cannot be formed, and the size of the object can be accurately measured only in the narrow portion of the observable range.

However, in the first embodiment, a plurality of, for example, three indexes 24a, 24b, 24c whose positions in the optical axis direction are different are provided as single fibers 19.
Since it is arranged between (can be regarded as a light source for illumination) and the positive lens 20 for illumination, the above-mentioned drawbacks are eliminated. That is, the fifth
As shown in the figure, indicators 24a, 24b by the positive lens 20 for illumination,
Since the image forming positions of the images 24a ′, 24b ′, 24c ′ of 24c are distributed over a wide range in the optical axis direction, either the index in the entire observable range in the optical axis direction or in a very wide area is used. The image will be sharp. Therefore, it is possible to accurately measure the size and the object distance of the object in the entire observable range in the optical axis direction or in a very wide area.

In the above, the frame sequential irradiation type color electronic endoscope is taken as an example,
A mosaic filter type color electronic endoscope may be used.
Further, ultraviolet light may be used instead of infrared light for the projection of the index image. Further, instead of fixing the single fiber to the exit end face of the light guide, the image of the exit end face of the light guide projected by the positive lens for illumination is not clearly identified within the observable range in the optical axis direction, that is, blurring occurs. The positional relationship between the positive lens for illumination and the exit end surface of the light guide may be determined so as to be imaged. Needless to say, the number of indexes is increased in proportion to the size of the observation range.

Next, various modified examples of the index and their image forming states will be described. In FIG. 6 (A), 31 is three horizontal linear markers 31 engraved or colored at different positions in the illumination optical axis direction.
The index plate having a, 31b, 31c, and the index image in the observation visual field is as shown in FIG. 6 (B).

In this case, if the intervals between the indexes 31a, 31b, 31c are too wide, there is a region where the index image is too blurred and cannot be seen, and the region cannot be measured. Therefore, the interval of each index is always
Even if there is some blur, it is necessary to set it so that it can be seen with the object. From this, the greater the number of indices and the narrower the distance between them, the more chances of observing the indices of sharper imaging.

FIG. 7 shows an example in which such an idea is developed and the indexes in FIG. 6 are connected in the optical axis direction. In FIG. 7 (A), reference numeral 32 is an index plate formed by engraving or coloring continuous indexes 32a in the illumination optical axis direction, and the index image in the observation visual field is as shown in FIG. 7 (B). In addition, there is an advantage that any part of the index 32a is always imaged on the object.

By the way, if the index is linear, the peripheral portion of the index image becomes invisible due to field curvature aberration, and FIG. 8 shows an example in which this is solved. That is, 33 is an index body in which three curved markers 33a, 33b, 33c along the spherical surface are engraved or colored at different positions in the illumination optical axis direction, and in this case, the index image 33a due to field curvature aberration. ′, 33b ′, 33c ′ become linear and the peripheral part of the image becomes visible.

FIG. 9 shows an example using the fact that the positive lens 20 for illumination has a very shallow depth of field. That is, this is a plurality of indices a ₁ , b
_Even if the magnification changes due to the fact that ₁ , ₁ , c ₁ , ... Are spaced at a predetermined distance in the direction along the illumination optical axis and the imaging position is different, these images a ₁ ′, b ₁ ′, c ₁ ′,. distance from the optical axis of ‥ is arranged set apart from the optical axis to be the same, yet these indicators relates to the optical axis _{a 1, b 1, c 1} , index a ₂ in ‥‥ symmetrical positions, b ₂ , c
It consists of _two , .... Then, because the depth of field of the positive lens for illumination 20 is very shallow, only a specific index pair is sharply imaged on the object for a certain object distance, and all other index pairs are blurred. Therefore, the object distance (magnification) can be obtained depending on which index pair forms a sharp image. In other words, the index image is used as a scale for measuring the object distance. Further, according to this example, each index image pair a ₁ ′,
a ₂ ′; b ₁ ′, b ₂ ′; c ₁ ′, c ₂ ′; The distance between the two is constant, so if the distance is used as a finger for measuring the size of an object, It is not necessary to provide a focusing screen having a reference index line in an optical system or the like.

FIG. 10 shows an essential part of the second embodiment, in which the index plate 34 having one index 34a or the illuminating positive lens 20 is made movable and the distance between the illuminating positive lens 20 and the index 23a is set. The index image 34a 'is made variable so that the image forming position of the index image 34a' in the optical axis direction is made variable so that a sharp index image 34a 'can be obtained in the entire observation range in the optical axis direction. It enables measurement. Also, a positive lens for illumination 20
Has a very shallow depth of field, so the focus or index image 34a '
The object distance (magnification) in the focused state can be obtained by the amount of movement of the positive lens 20 for illumination or the index plate 34 that is moved to form an image on the object, and it is possible to measure the size of the object. is there. In this case, since the depth of field of the illumination positive lens 20 is shallower than that of the objective lens, the accuracy is higher than that when the objective lens is used. Further, by increasing the movement amount of the positive lens for illumination 20 or the index plate 34 so that the image forming position of the index image is brought out of the depth of field of the objective lens, when the index is unnecessary such as during normal observation. It is convenient because you can erase the index image.

In this embodiment, when the index plate 34 is moved, there is an advantage that the light distribution state of the illumination does not change. Further, the focal length of the positive lens for illumination may be variable only for the purpose of obtaining a sharp index image 34a 'in the entire observation range in the optical axis direction.

FIG. 11 (A) shows an application example of the second embodiment, 35 is an image guide, 36 is an eyepiece lens, and 37 is an image guide.
A focusing screen (see FIG. 11 (B)), which is disposed between the exit end of 35 and the eyepiece lens 36, and has a cross reference index 37a in the center and slits 37b in the periphery (see FIG. 11 (B)), and 38 is the focus. On the eyepiece side of the plate 37, which is arranged rotatably around the optical axis, has a notch 38a in the peripheral portion, and moves in the optical axis direction of the focusing plate 34 through an interlocking mechanism composed of a wire 39, a reel 40, etc. It is a ring (FIG. 11 (B)) that is rotated in conjunction with movement. According to this example, the ring 38 rotates in response to the movement of the index plate 34 for focusing, that is, the image of the index image on the object in the optical axis direction, and the notch 38a is formed in front of the slit 37b. Slit 37b visible through eyepiece 36 as it moves
Varies depending on the focusing operation. That is, since the length of the slit 37b changes according to the change in the object distance,
It is possible to cause an object pointing with a length corresponding to the object distance to appear next to the object image in the field of view.

Needless to say, in each of the above examples, an LED, a semiconductor laser, a light bulb, or the like may be used instead of the light guide. Further, the index can be made of an electrochromic element, liquid crystal or the like, and can be turned on or off as needed.

〔The invention's effect〕

As described above, the measuring endoscope according to the present invention is extremely important in practical use because it enables accurate measurement of the size of an object and the object distance in the entire observable range in the optical axis direction or in a very wide area. Have advantages.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of a measuring endoscope according to the present invention, FIGS. 2 and 3 are front views of a rotary filter and an index plate of the first embodiment, respectively. Is a graph showing the transmission characteristics of the filters of the first embodiment, FIG. 5 is a diagram showing the image formation state of the index image of the first embodiment, and FIGS. 6 to 9 are various modifications of the indexes. FIG. 10 is a diagram showing the essential parts of the second embodiment, FIG. 11 is a diagram showing an application example of the second embodiment, and FIG. 12 is a configuration and index of the conventional example. It is a figure which shows how a board, a focusing screen, and the index in an observation visual field look. 11 …… Hard tip part, 12 …… Flexible part, 13 …… Light source / video circuit part, 14 …… Light source lamp, 15 …… Condensing lens, 16 …… Rotating filter, 17 …… Motor, 18,36 ...... Light guide, 19 …… Single fiber, 20 …… Lighting positive lens, 21 ・ ・ ・
… Object, 22 …… Infrared cut filter, 23 …… Visible cut filter, 24, 31, 32, 34 …… Index plate, 25 …… Objective lens, 26 …… Stopper, 27 …… Solid-state image sensor, 28… … Video circuit, 29 …… TV monitor, 30 …… Reference index line, 33 …… Indicator, 35 …… Image guide, 37 …… Focus plate, 38 …… Ring, 39 …… Wire, 40 …… Reel.

Claims (2)

[Claims] 1. An illumination optical system having an illuminating light source and an illuminating positive lens system for projecting light from the illuminating light source onto an object through the illuminating positive lens system, and an objective lens. In an endoscope having an observing or photographing optical system arranged in parallel with the illuminating optical system, in a direction along the illuminating optical axis between the illuminating light source and the illuminating positive lens system. An endoscope for measurement, wherein a plurality of indices at different positions or continuous indices are arranged in a direction along an illumination optical axis. 2. An illuminating optical system having an illuminating light source and an illuminating positive lens system for projecting light from the illuminating light source onto an object via the illuminating positive lens system, and an objective lens. In an endoscope having an observing or photographing optical system provided in parallel with the illumination optical system, an index is arranged between the illumination light source and the illumination positive lens system, and the index is provided. An endoscope for measurement, wherein an interval between the positive lens system for illumination and the positive lens system for illumination is variable.