JPH0412724A - Measuring endoscope - Google Patents

Abstract

PURPOSE:To execute the detailed three-dimensional position measurement to a measuring object without executing a large scale correlation calculation by sweeping a sector light, processing an image of the sector light projected to the measuring object, and obtaining three-dimensional information of the measuring object. CONSTITUTION:An output signal of an image pickup element 51 being a part of an image pickup device 12 is subjected to processing such as amplification, etc., by a controller 52, sampled and quantized by an A/D converter 53, inputted to a computer 54 and various arithmetic processings are performed. On the other hand, a controller 56 applies a control signal for sweeping a sector light 14 to a sector light projecting device 55 (13), and outputs a signal for showing the sector light projecting direction to a computer 56. In such a state, by varying an intersection angle of the center line of the sector light 14 and a visual line of a camera to the tip side of the scope and sweeping the sector light 14, a measuring object is photographed, and by a trigonometrical survey principle between the sector light position and the image pickup position in an image, three-dimensional information of a measuring object is derived. Accordingly, the three-dimensional information of the measuring object is obtained densely without using a correlation operation between plural images, which necessitates a long processing time and a large-sized computer.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to improvement of a medical endoscope device,
More specifically, the present invention relates to a measuring endoscope that accurately measures the size and position of lesions such as polyps by obtaining three-dimensional information inside an organ, which is useful for diagnosis.

BACKGROUND OF THE INVENTION Endoscopes are essential for diagnosis of organs such as the stomach, intestines, or bladder. However, conventional endoscopes mainly rely on observation, making it difficult to accurately measure the size of lesions such as polyps. In other words, the doctor must estimate the three-dimensional information of the measurement object projected onto the two-dimensional plane based on intuition.
There are problems in that it requires the skill of a doctor, individual differences in measurement occur between doctors, and objective data cannot be obtained. Therefore, several endoscopes with additional measurement functions have been developed. Here, two representative examples of such endoscopes will be described as prior art, and their problems will be described. (Conventional Example 1) An endoscope that obtains three-dimensional information of a measurement target from multiple images from different viewpoints.An example of this conventional technology is Japanese Patent Application No. 1983-20]618
There is a number. This conventional technology performs stereoscopic viewing using a plurality of images taken from different viewpoints. The basic principle of this measurement method will be briefly explained using Fig. 2. In Fig. 2, 01 and O2 are the center positions of the objective lens, and C1vC2 is the image plane p1.1.
t is the center position, f is the focal length of the lens, and 1 is the distance between the centers of the two lenses. , A is a measurement point on the surface of the object to be measured, and ZA is the distance from a plane including C3 and O2 and parallel to the image plane P, , P to point A. In this case, point A appears at position a on the image plane pI, and at position a on the image plane p. Therefore, when the centers of these two images are superimposed, a, corresponds to the position of a, - on the image plane p. Applying the principle of trigonometric measurement to these two points a, a,'', △A O, O,
From the similarity relationship of and △02 a (-a 2, ZA= f -1/c1. (]) can be obtained. However, d is the distance between a and a. On the other hand, △○, c, a l and △O, H
From the similarity relationship of A, xA=e, + ZA/f (2), so
Substituting equation (1) into equation (2), xA=e, -1/d
a (3) and the horizontal position XA are found. Here, e is the distance between Ca1. The vertical position can also be determined in exactly the same way as the horizontal position. In this way, when corresponding points are determined for multiple images, three-dimensional information of the measurement points can be obtained from equations (1) and (3), and for example, the length between any two points can be determined. . This determination of corresponding points is performed by selecting a small region with the highest correlation from a plurality of images using Fourier transform or the like. Then, a method is used in which the interval between the selected small areas is determined by calculating the distance d between two pairs of corresponding points. When this method is used for an image consisting of several hundred horizontal and vertical images, there are problems such as not only a long processing time is required for correlation calculation, but also a large-sized computer is required. An endoscope to solve this problem was developed in the patent application filed in 1977-145.
619. This method improves the above drawback by having the operator teach measurement points to multiple (usually two) images displayed on a monitor, thereby omitting the correlation calculation for corresponding determination points. It is. This makes it possible to easily obtain three-dimensional information about the specified measurement point. However, there is a problem in that multiple teaching operations are required to obtain detailed three-dimensional information. In addition, this method requires accurate teaching on a pixel-by-pixel basis, which places a heavy burden on the operator, and there is also the problem that the teaching is not an objective measurement because the operator's subjectivity is involved. (Conventional Example 2) An endoscope that projects a two-dimensional spot light pattern to obtain three-dimensional information on the measurement target (this example of the conventional technology uses a
240831). As shown in FIG. 3, in this invention, a laser beam 32 emitted from a laser light source 31 is incident on a transmission type fiber diffraction grating 33, and two-dimensional spot beams 34 arranged in a matrix are projected onto a measurement target. . Then, an image on which this spot light pattern is projected is captured. The image of this spot light pattern consists of spots arranged in a matrix according to the shape of the object to be measured. Since the interval between the two images changes, three-dimensional information about the object to be measured can be obtained by determining the position of the spot light in the image. The basic principle of this measurement method will be briefly explained using FIG. 4. In FIG. 4, φ is the direction of the h-th order spot, and φゎ is the direction in which the h-th order spot is visible. The same symbols as in FIG. 2 are used for other parts. From Fig. 4, ZA is ZA=1/(tanθh −tanφh
)=l/(e,/f−tanφh) (4). On the other hand, regarding XA, the obtained ZA is expressed by the formula (
It can be found by substituting 2). Note that φ is obtained by φ,==5 in-'(h2./D) (5). Here, λ is the wavelength of the laser beam, and D is the pitch of the diffraction grating. As explained above, this method measures the spot light projection position. Therefore, only coarse three-dimensional information of the measurement target can be obtained. That is, there is a problem that the resolution is equal to the projection interval of the spotlight. As a result, when measuring the size of a polyp, for example, there is a drawback that accurate information cannot be obtained. Furthermore, in this method, it is necessary to accurately recognize the diffraction order of the spot light to be measured, that is, to calculate equation (4) using the correct φ7. Therefore, if this recognition is incorrect, ZA calculated by equation (4) will include a large error. For this reason, a method has been considered in which the diffraction grating is modified to brighten only the zero-order spot light, which serves as the reference for measurement. (Yamaguchi et al., Gastroentelionical
Endoscopy pp86B-874vol,
(25) 6. Jun, 1983) However,
Due to specular reflection of non-zero-order spot light or zero-order spot light being projected onto areas with low reflectance, spots of other orders may be mistakenly recognized as zero-order, or spot light of a certain order may be missing. It is expected that recognition of the order will fail, such as not being observed. The purpose of the present invention is to
An object of the present invention is to provide an endoscope that can perform detailed three-dimensional position measurement of a measurement target.

[Means to solve the problem]

The present invention provides a means for emitting a narrow beam of light, a means for converting the emitted narrow beam of light into a fan-shaped light, and a center line of the fan-shaped light intersects with the visual axis of the camera, and measurement is performed by changing the angle of this intersection. The distal end of the scope is equipped with a fan-shaped projection means consisting of a means for sweeping fan-shaped light projected onto the object, and an imaging means for taking an image of the measurement object and the projected waist, and a fan-shaped projection means configured to sweep the fan-shaped light projected onto the object, and an imaging means for taking an image of the measurement object and the projected waist. The apparatus has an image processing means for obtaining three-dimensional information of the measurement target based on the position of the projected pickpocket light on the image.

[Effect]

According to the above configuration, the object to be measured is imaged by sweeping the fan-shaped light by changing the intersection angle between the center line of the fan-shaped light and the visual axis of the camera on the distal end side of the scope, and the position of the fan-shaped light in the captured image is The three-dimensional information of the measurement target can be obtained by applying the principle of triangulation between the camera and the imaging position.

【Example】

Hereinafter, the present invention will be specifically explained with reference to the drawings. FIG. 1, FIG. 5, FIG. 6, and FIG. 7 are diagrams for explaining the present invention in detail. FIG. 1 is a general view of the distal end of a measuring endoscope, and shows an example of a side-viewing endoscope. 11
12 is a main body, 12 is an imaging device including an objective lens, an image sensor, etc., 13 is a fan-shaped light projection device, 14 is a projected fan-shaped light, and 15 is an illumination device. However, only one fan-shaped light is projected at each moment, and this fan-shaped light is swept. 14 is an overwritten version of this. FIG. 5 shows a block diagram. The output signal of an image sensor 51 such as a CCD, which is a part of FIG. 54. This computer performs various calculation processes described below. On the other hand, the controller 56 provides a fan troll signal to the fan-shaped light projection device 55 to perform a sweep as indicated by reference numeral 14 in FIG. 1, and outputs a signal indicating the fan-shaped light projection direction to the computer 54. FIGS. 6 and 7 show means for emitting a narrow beam, means for converting this beam into fan-shaped light, and means for sweeping the fan-shaped light, which constitute the fan-shaped light projection device. FIG. 6 is a sectional view taken along a plane defined by the center line of the fan-shaped light and the camera viewing axis, and FIG. 7 is a sectional view taken in a direction perpendicular to the plane. In both figures, 61 is a fiber for transmitting measurement light, and 62 is a lens for converting this light into fan-shaped light. This lens creates fan-shaped light 63 focused in the sweeping direction. The fan-shaped light 63 is reflected by a rotating mirror 64, and due to this rotation, the fan-shaped light 65 is swept and projected onto the measurement target. The 6th is the scope body shown in FIG. 11. The rotating shaft 67 provides rotational movement to the rotating mirror 64 via the gear 66 . This causes the rotating mirror to rotate and the fan-shaped light to be swept. The rotating shaft 67 is driven by a motor mounted inside the scope or at hand. Using the embodiment described above, an image processing means for obtaining three-dimensional information of the measurement object from the position on the image of the fan-shaped light projected onto the measurement object will be explained. FIG. 8 is a diagram for explaining the measurement principle, in which the rotating mirror rotates around the rotation center R. The fan-shaped light enters the center R and is swept. In FIG. 8, point A is an arbitrary point on the fan-shaped sales, and calculations are performed in the same way for all points forming the fan-shaped light. By simple geometrical calculations similar to those shown in FIG. 2, ZA is determined to be 6° tanφ. When ZA is determined, the horizontal position XA is a xA= ZA
Calculated in (7). Regarding the vertical position, e
By using the position of the fan-shaped light in the direction perpendicular to the optical axis instead of , it can be obtained similarly to equation (7). In equation (6), l, s, and f are measured in advance, and φ is obtained from the rotation angle and gear ratio of the motor. Note that detailed three-dimensional information of the measurement target can be obtained by making φ smaller than the imaging time interval. An embodiment of the image processing means based on the above measurement principle will be described. FIG. 9 is a flowchart of the embodiment. Step 101: The imaging device images the measurement target onto which the fan-shaped light is projected. As mentioned above, the captured image is sent to the controller,
The image is stored in the computer's image memory via an A/D converter. The fan-shaped light image stored in the image memory is shown in FIG. The image is sampled into several hundred pixels in both the x and y directions, and the brightness is quantized into 100 to several 100 gradations. Step 102: Fan-shaped light projection direction input The fan-shaped light projection direction necessary for calculating the three-dimensional position of the fan-shaped light projection position is input from the controller 56 to the calculator 54 shown in FIG.
Enter. Step 103: Detecting the position of the fan-shaped light The position of the fan-shaped light in the image shown in FIG. 10 is detected. In FIG. 10, a U coordinate e6 is detected for each V coordinate, which is a sample point in the spreading direction of the fan-shaped light. Here, the U coordinate is parallel to the X coordinate, and the ■ coordinate is parallel to the X coordinate. Normally, fan-shaped light is distributed over multiple pixels even in the focused direction. Therefore, the coordinates of the brightest pixel, which is the center position, is used as the position of the fan-shaped light. In particular, when highly accurate measurement is required, for example, Japanese Patent Application No. 60-244051
The fan-shaped light position can be accurately determined using the method shown in the above issue. Step 104 - Three-dimensional position measurement The fan-shaped light projection direction φ obtained in step 102 and Step 10
Substituting the fan-shaped light position detected in step 3 into equation (6), the distance Z
Calculate A. Next, the horizontal position XA is calculated using equation (7). The vertical position is obtained by substituting v, , in place of e6 in equation (7). The above steps 101 to 104 are repeated until the fan-shaped light sweeps the entire screen. Note that steps 101 to 103 may be repeated, all fan-shaped light positions may be stored in memory, and finally step 104 may be processed all at once.

【Effect of the invention】

As described above, the measurement endoscope of the present invention obtains three-dimensional information of the measurement target by sweeping the fan-shaped light and processing the image of the fan-shaped light projected onto the measurement target. Therefore, compared to conventional measurement endoscopes, it has the advantage of being able to obtain detailed three-dimensional information about the measurement target without using correlation calculations between multiple images that require long processing times and large computers. There is. As a result, it becomes possible to accurately obtain the size and shape of lesions such as polyps, which are important for organ diagnosis.

[Brief explanation of the drawing]

Figure 1 shows an overview of the distal end of the measuring endoscope of the present invention. Figure 2 shows the measurement principle of a conventional endoscope that obtains three-dimensional information of a measurement target from multiple images from different viewpoints. Diagrams for explaining, Figures 3 and 4 are diagrams for explaining a conventional endoscope that projects a two-dimensional spot light pattern to obtain three-dimensional information of a measurement target. Fig. 4 is a diagram for explaining the measurement principle; Fig. 5 is a block diagram of the present invention; Figs. 6 and 7 are the measurement endoscope and Shubbu of the present invention. FIG. 6 is a side view, FIG. 7 is a front view, and FIG. 8 is a diagram for explaining the measurement principle of the measurement endoscope of the present invention. , Fig. 9 is a flowchart for obtaining three-dimensional information of a measurement target from a captured image, and Fig. 1o is a diagram showing an example of an image obtained by capturing a fan-shaped light stored in an image memory. be. 11... Endoscope main body, 12... Imaging device consisting of an objective lens, image sensor, etc., 13 - Fan-shaped light projection device,
14... Fan-shaped light, 15... Lighting device, 61...
...Fiber for transmitting light for measurement 62...
... Lens for converting into fan-shaped light, 63 Fan-shaped light, 6
4... Rotating mirror 65... Swept fan-shaped light, 6
6... Gear, 67... Rotating shaft, 68... Endoscope body. Figure 1 Figure 3 Figure 2 Figure 4 Figure 5 Figure 7 Figure 9 Figure 8 Coordinates

Claims (1)

[Claims] Means for emitting a narrow beam of light, means for converting the emitted narrow beam of light into a fan-shaped light, a center line of the fan-shaped light intersects with the visual axis of the camera, and the angle of this intersection is changed. a fan-shaped projection means comprising a means for sweeping a fan-shaped light projected onto a measuring object; and an imaging means for taking an image of the measuring object and the projected fan light at the distal end of the scope; A measurement endoscope comprising an image processing means for obtaining three-dimensional information of a measurement target based on a position on an image of a slit light projected onto the target.