JPH01200214A - Measuring endoscope device - Google Patents

Abstract

PURPOSE:To facilitate discrimination of a pattern on a picked-up image to precisely detect it by alternately irradiating it with an uniform light projecting means which generates a uniform quantity of light throughout the pattern and an emphasizing light projecting the pattern and an emphasizing light projecting means which emphasizes only a specific part. CONSTITUTION:An output laser light 29 of an oscillator 28 is separated to two kinds of irradiating light of the transmitted light and the reflected light by a chopper 30 rotated by a motor 31. The chopper 30 is provided with a slit part, a mirror part, and a shield area, and two kinds of impulsive irradiating light which are separated in accordance with rotation of the chopper 30 with respect to time are made incident on fiber input manipulators 33 independent of each other and pass two light guides 34 and are emitted from a diffraction grating 23 arranged in a front end part 21 of a scope 3. Since they pass different parts of the diffraction grating 24, they are projected to an object as two kinds of irradiating light one of which is the irradiating light having a uniform quantity of light and the other of which is the emphasizing light where a larger quantity of light is distributed to only a specific part.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention captures an image by irradiating it with a two-dimensional regular pattern of light, and non-contactly measures the irregularities of the subject based on the distortion of the pattern. The present invention relates to a measurement endoscope apparatus for carrying out a photographic process, and more specifically, to an improvement in the irradiation mechanism of the apparatus to make it easier to detect the pattern from a captured image of a subject.

(Prior art) A scope is introduced into the object to be observed, such as a mechanical device, an extinct object, or a human body, and an optical imaging system installed at the tip of the scope images one object 'j'' F inside the body cavity. [Endoscope devices are used in various fields.

This endoscope is equipped with a means for generating a two-dimensional regular pattern of light, such as a laser spot array, and projecting it onto the subject.The endoscope measures the distortion of the pattern in the captured image and measures the three-dimensional shape of each part of the subject's surface. There is a so-called measurement endoscope device that obtains information on the shape of irregularities, etc. = tn.

An example of a method for obtaining two-dimensional regular pattern light is shown in the 14th section.
For example, several meters of glass fibers 26a and 27a with a diameter of about 20 μm are arranged in parallel without any gaps.
A diffraction grating 23 is used, which is made by laminating two sheets 26 and 27 of about m square so that the fibers of each layer are orthogonal to each other.

As shown in FIG. 15, two laser beams emitted from the oscillator 28 of the laser light source are perpendicularly incident on the diffraction grating 23, so that an array of bright spots in the form of a square lattice (hereinafter referred to as spot light) is formed in front of the diffraction grating 23. 25 can be generated.

Using such a pattern light generating means, as shown in FIGS. 12 and 13, a spot light 25 is projected from the endoscope scope tip 21 onto the subject 24, and an imaging unit (for example, a solid-state image sensor) is projected with a parallax Pa. Photographs are taken using an element (CCD) 22.

Note that, although an optical system such as an objective lens is actually arranged just in front of the image pickup element 22, it is not shown here for the purpose of simplifying the explanation, and will be explained as one with the image pickup element 22. In FIG. 12, the distal end portion 21 of the endoscope includes an illumination hole into which an illumination light kite and an irradiation lens (not shown) are fitted, an air/water supply hole, a forceps hole which also serves as a suction hole, and the like.

The diffraction grating 23 and the light guide 34, which guides the irradiation light from a laser light source oscillator, etc. as a pattern projection light source inside the endoscope body, to the diffraction grating 23, use the forceps hole and its passage to It may be introduced up to the section 21, or it may be provided separately for exclusive use.

FIG. 11 shows how the spotlight 25 is applied to the subject 24 in this way.
This is an example of an image taken by projecting .

In addition to such spot light, a vertical striped pattern may be generated as a regular pattern of light and projected onto the subject. FIG. 10 is an example of an 11@L image created by vertical striped pattern light.

If the subject has irregularities, the parallax Pa will cause distortion in the pattern of the captured image. By measuring the degree of this distortion, it is possible to calculate the three-dimensional position of each point on the surface of the subject. Since the principle of this calculation is well known, its explanation will be omitted.

(Problem to be Solved by the Invention) However, in order to accurately detect pattern distortion as described above, calculation results may be affected if each point between the projected pattern and the pattern on the photographed image does not correspond correctly. Errors occur.

As described above, the pattern light projection unit (diffraction grating 23)
Parallax Pa between the quadrant (image sensor 22 including lens etc.)
This causes distortion of the pattern light on the image, but this distortion appears only in the direction parallel to the parallax Pa (left-right direction in FIG. 11).

In determining each spot on the pattern, spot rows that are in the same series in the direction perpendicular to the parallax Pa (vertical direction in FIG. 11) are called, for example, the same order or homogeneous term. Then, the spot row located exactly in the center is set as the O-order term, and the +1st-order term, +2nd-order term, ..., the 11th-order term, -2nd-order term, etc. are sequentially added to the right side of Fig. 11, and the 11th-order term, -2nd order term, etc. to the left side of Fig. 11. Name and categorize.

At this time, if terms of any order are projected with approximately the same amount of light,
When a captured image is binarized and a pattern is detected, the patterns of any order have approximately the same size, making it difficult to distinguish the order. For this reason, in order to easily distinguish the order, conventionally, only spot sequences of a specific order, for example, the 0th order term, are
A method has been adopted in which the spotlight is projected with a larger amount of light than the spotlights of other orders.

However, the surface of the subject is naturally not flat;
The surface condition is not always suitable for photographing, as there are irregularities, distance, etc., and if it is an internal organ of a large tree, the mucous membrane may be wet. Therefore, when detecting patterns by binarization processing, emphasis is In some cases, the imaged pattern of the zero-order term may ooze out, making it difficult to separate it from the adjacent pattern of the ±1st-order term. Furthermore, since the light emitted from the same light source is projected by distributing a larger amount of light to the zero-order term, the light amount of the surrounding multi-order terms may be insufficient, which may result in spot detection failure. For this reason, the correspondence between each point on the image cannot be determined correctly, causing errors in measurement.

The present invention aims to solve this problem in view of the conventional circumstances, and emphatically projects a specific part of a pattern, for example, the O-order term, so that the pattern on the captured image can be easily distinguished. It is an object of the invention to provide a pattern light projection means for a measurement endoscope that is less likely to cause seepage or omission when detecting a pattern on an image.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve such an object, the measuring endoscope device according to the present invention has the following features: uniform light irradiation means for generating irradiation light with a substantially uniform amount of light; emphasis light irradiation means for generating irradiation light that emphasizes only a specific portion of the pattern by increasing the amount of light than other portions; and the emphasized light irradiation. and an irradiation switching means that temporally alternately switches and irradiates both the irradiation lights from the uniform light irradiation means.

(Function) According to the measurement endoscope device equipped with each of the constituent means as described above, as the two-dimensional regular pattern of irradiation light projected onto the subject, the uniform light irradiation means generates irradiation light over the entire pattern area. Two types of irradiation light can be used: irradiation light with a substantially uniform amount of light and irradiation light that is generated by the emphasis light irradiation means and emphasizes only a specific part of the pattern with a larger amount of light than the pond part. Then, by irradiating these two types of irradiation light by alternating temporally with the irradiation switching means and irradiating one symptom, the pattern photographing surface (' A and an image with enhanced light that makes it easy to distinguish specific parts of the pattern can be obtained.If you observe these two types of pattern #ii shadow images while comparing them, you can easily recognize the pattern. This makes it possible to more accurately measure the unevenness of the surface of the object.

In this way, it becomes possible to solve the above-mentioned problems.

(Example) Hereinafter, each example of the measuring endoscope apparatus to which the present invention is applied will be described in detail based on the drawings.

FIG. 1 is a block diagram showing the main structure of a measuring endoscope device according to an embodiment of the present invention.

In addition to the normal endoscope irradiation light source 1, it emits two types of irradiation light that has a two-dimensional regular pattern and has a substantially uniform amount of light over the entire area, and irradiation light that emphasizes a specific part. The pattern projection light source 2, which is the light source for the projection, is swerved.

In addition, the camera control unit (hereinafter abbreviated as CCU), which is a component of the main body of the endoscope device of Tsuzu 7, is
4, decoder 5, A/D 6, frame memory 7, D/A
8 and the monitor 9, various units for performing measurements, calculations, and displaying the results are provided.

That is, there is an A/D 10 that converts an analog video signal from the CCU 4 into a digital signal value, a uniform image memory 11 that stores an image taken with uniform irradiation light, and an enhanced image memory 12 that stores an image taken with emphasized light. . For example, 8 pixels per pixel are stored in both image memories 11 and 12.
A reference level generation unit 13 provides a reference level for binarization when converting image data with a bit depth into binary data of only 1 and 0 depending on whether it is larger or smaller than a predetermined level value. There is a comparison section 14 that compares this reference level with each of the above-mentioned image data, and a binarization processing section 15 that converts and holds the binary data represented by only 0 or 1 according to the comparison result.

There is a thinning processing section 16 and a spot center detection section 17 that detect the center point (or center line) of the pattern based on the binarized image obtained in this way.

Further, there is a calculation unit 18 that calculates the three-dimensional coordinate value of each point from the amount of distortion of the coordinate value of the center point of this pattern etc. from the original pattern. There is an output processing unit 19 that forms a display image edited into numerical information or an easily recognizable figure from the calculated three-dimensional coordinate values of each point, and displays it on the monitor 9.

FIG. 2 is a diagram showing an example of the internal configuration of the pattern projection light source 2 described above.

As an example of the configuration of a means for generating two types of irradiation light, ie, irradiation light with a substantially uniform amount over the entire area and irradiation light with an emphasis on a specific part, as shown in FIG. , the output laser beam 29 is transmitted or reflected by a chopper 30 rotated by a motor 31.
It is separated into two irradiation lights.

FIG. 3 shows an example of the shape of this chopper 30.

A slit 30a and a mirror 30b of the same shape are provided line-symmetrically on the left and right sides of a disk-shaped chopper 30.

The slit 30a is a notch that allows the two laser beams to pass through as is, and the mirror 30b is a mirror that reflects the laser beam 29 and changes the direction of the optical axis. Moreover, the remaining portion other than this is a shielding area that shields the two laser beams and prevents them from being output in either direction.

This disk-shaped chopper 30 rotates continuously, for example, counterclockwise in FIG. 3, with the center point of the circle as the rotation center.

When the chopper 30 is rotated by the motor 31, for example, counterclockwise in FIG. 3, the laser beam 29 that has reached the chopper 30 is transmitted through the slit 30a and goes straight, and is reflected at right angles in the mirror 30b. The light is then reflected again at right angles by the mirror 32 to become light having an axis parallel to the original optical axis. Further, when the laser beam 29 is not located in either area, the laser beam 29 is blocked and is not output.

In this way, two pulsed irradiation lights are generated which are separated into two different paths and are also temporally separated.

These two irradiation lights enter separate fiber manipulators 33, are guided by two light guides 34, and reach a diffraction grating 23 disposed at the tip 21 of the scope 3. By passing through different parts of this diffraction grating 23, one is irradiated light with a substantially uniform amount of light, and the other is emphasized light with a large amount of light distributed only to a specific part of the two-dimensional regular pattern. Two types of irradiation light with different light intensity distributions are irradiated onto the subject.

In addition, this chopper 30 and motor 31 are integrated,
It is configured to be movable diagonally in the upper right and lower left directions in FIG. 3 by a drive unit such as a second motor (not shown).

When the chopper 30 and the motor 31 are moved together in the diagonal direction in the figure, the laser beam 29 from the oscillator 28 reaches a portion near or around the center of rotation of the chopper 30. When the two laser beams reach a portion close to the rotation center of the chopper 30, as is clear from FIG. The pulse width becomes shorter. Further, when the laser beam 29 reaches the peripheral part of the chopper 30, the mirror 3
The proportion of time reflected and transmitted by 0b and slit 30a increases, and the pulse width of the irradiated light increases.

For example, a laser beam 2 is placed on a circumference R with a radius r shown in FIG.
When the laser beam 29 reaches the lower part of the circumference R, the light is blocked and no irradiation light is generated. When the chopper 30 rotates in the direction of the arrow in the figure, the laser beam 29 is transmitted to the mirror 30b of the circumference R.
The irradiation light reaches the area and produces a substantially uniform amount of irradiation light. When the chopper 30 rotates further, it reaches the shielding area again and no longer emits light. Then, when entering the region of the slit 30a, irradiation light as the other emphasis light is generated. In this way, two types of pulsed irradiation light can be generated.

FIG. 4 is a diagram showing an example of the output timing of the two types of irradiation light generated by the rotation of the chopper 30 described above.

The operation method of the image sensor 22 in this embodiment device is as follows:
For example, ODD/EVE using frequency interleaving method
If one frame image is composed of two N fields, for example, an image using uniform illumination light is captured in the ODD field, and an image using emphasized light is captured in the EVEN field for comparison. be able to. The output timing example of the irradiation light in FIG. 4 assumes such a system, and furthermore, by moving the part where the laser light 29 is applied to the chopper 30, the pulse width of the uniform light and emphasized light can be changed. It changes from long to short.

The two types of irradiation light thus obtained are guided to the distal end portion 21 of the endoscope 3 by separate light guides 33 and reach the diffraction grating 23.

- As a method of obtaining two types of pattern projection irradiation light, uniform and emphasized, using the diffraction gratings 23, for example, as shown in FIG. There is.

As shown in FIG. 5, when the laser beam guided by the light guide 33 hits the center of the diffraction grating 23, an approximately uniform square lattice-shaped bright spot array (
Spot light) is obtained, and a subject image as shown in FIG. 7 is obtained Lm (i).

Furthermore, when the end of the diffraction grating 23 is irradiated with light as shown in FIG. ), the irradiated light on the right side of the figure is diffracted only in the vertical direction in the figure and travels straight without being affected in the horizontal direction, so that only the central part of the pattern, that is, the O-th order term, is emphasized. FIG. 8 shows an example of imaging using this emphasized projection pattern irradiation light. The large black circle near the center of FIG. 8 is the 0th-order term that is emphasized and projected.

In this way, two types of irradiation light can be guided using two light guides, and two types of projection patterns can be obtained. Note that the diameter of the Lye I-Guide 1 is about 50 μm, and even if two of them are used, the inner diameter of the endoscope's I-G introduction part will not be affected.

The reflected light projected onto the subject and reflected from the surface is captured by an image sensor 22 disposed at the distal end 21 of the endoscope 3.
The light enters the camera, is imaged, and is sent as an electrical signal to the camera control unit (CCU) 4 shown in FIG. C.C.
U4 performs signal processing on this electricity No. 13, and converts it into, for example, a luminance signal E111 of an analog video signal and two color difference signals (Ey-
Er) and (Ey-Eb).

For example, the luminance signal [y of the analog video signal outputted from the CCUd is the A/D1. Digitized by O.
The irradiation and tm ('A) are stored in the uniform image memory 11 or the emphasized image memory 12 in synchronization with the timing of A.

When the two fields of ODD/EVEN are imaged and the image data is stored in the two memories, pattern detection and three-dimensional position calculation processing based on the amount of distortion are performed.

First, the reference level generation unit 13 outputs a reference level for binary conversion when converting into binary data of only 1 and 0. With respect to this reference level, the value of each pixel of the image data stored in both the image memories, the uniform image memory 11 that stores images taken with uniform irradiation light and the emphasized image memory 12 that stores images with emphasized light, is calculated by the comparing section. It is compared by 14. Depending on the comparison result, the binary data is converted into binary data represented by only 0 or 1 by the binarization processing unit 15 and is held.

Based on the binarized image obtained in this way, the thinning processing unit 16
In this step, thinning processing is performed to reduce the peripheral portion of a data area having a value of 1.

Furthermore, the spot center detecting section 17 detects the center point (or center line) of the pattern, and determines the center point (or center line) of each corresponding pattern of the two types of detected images.

Then, in the calculation unit 18, the three-dimensional coordinate value of each point is calculated from the amount of distortion between the coordinate value of the center point of the pattern, etc., and the corresponding point of the original pattern.

Here, the relationship between the spot light coordinate and the distance of the corresponding point on the surface of the subject is as follows:
(h), the center coordinate is Xc, the viewing angle is 2β, and the 12th
In the figure, the corresponding point on the surface of the subject of order h and the image sensor 2
Let θh be the angle formed by the line connecting the center point O of 2 and the Z axis at the center of the screen: tanθh = (Xs(h) −x
C) Represented by tanβ/Xc.

Also, the vertical distance 7h to the object surface of the 11th order term is; Zh
It is expressed as =Pa/(tanθh −tanψh). Here, Pa is the parallax and ψh is the diffraction angle of the h-order term.

Furthermore, if d is the distance between the irradiation center of the end of the diffraction grating that is guided and irradiated by the light guide for emphasized irradiation light and the irradiation center of the center of the diffraction grating by the light guide for uniform irradiation light, then The actual coordinates of the zero-order term position due to the emphasized irradiation light and the zero-order term position due to the uniform light are deviated by a value δ expressed by δ−d/(20tanβ)−Ps. For this reason, it is necessary to shift the coordinate values of each order term by the emphasized irradiation light by the above value δ.

The three-dimensional coordinate values of each point calculated in this way are edited into numerical information or easily recognizable figures in one output processing section. The easily recognizable display image thus formed is displayed on the monitor 9.

Note that the present invention is not limited to the configuration of the above-described embodiment, and can of course be applied to, for example, a vertical striped projection pattern as shown in FIG. In addition, the method of obtaining two types of irradiation light is not limited to the above-mentioned one configuration example, but it is also possible to distribute the two types of irradiation light by disposing a swingable mirror or the like on the optical axis of the laser beam, for example. Alternatively, a configuration may be adopted in which a plurality of oscillators or the like that generate laser light are provided and oscillated separately. Of course, the shape of the chopper 30 described above is just an example, and is not limited to this shape. Furthermore, methods for achieving a two-dimensional regular pattern of projected light include not only the method described above that utilizes a diffraction grating structure in which sheets of transmission glass fibers are arranged in parallel in a single layer are stacked vertically and horizontally. It is of course possible to use other methods such as a deformed grid. Further, the imaging method is not limited to the above-mentioned field method, but is also applicable to other methods such as a frame method and a frame sequential method.

[Effect of the invention] As explained in detail above, the total effect of this invention is as follows.
An endoscope device projects a two-dimensional regular pattern of irradiation light onto a subject, with uniform irradiation light having an approximately uniform amount of light over the entire area, and a certain part of the pattern having a larger amount of light than other parts. There are two types of irradiation light, ie, an emphasis irradiation light that has a ray of light, and a irradiation light that has a radial effect.

For this reason, it is possible to extract patterns by capturing images using these two types of irradiation light and comparing and corresponding them.In images captured using 9-enhanced light, it is easier to distinguish specific parts of the pattern, and the projected pattern You will be able to respond without error. On the other hand, there may be adverse effects such as the imaged pattern in a specific part due to emphasis seeping out or merging with adjacent patterns, or missing patterns due to lack of light in other parts that are not emphasized, by comparing them with images taken under uniform light. By doing so, it becomes possible to accurately detect patterns. In this way, the shape of the object surface can be measured more easily and quickly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a measuring endoscope device according to an embodiment of the present invention, and FIG. Figure 3 is a diagram showing an example of the shape of the chopper in the same configuration example, Figure 4 is a timing diagram of irradiation and imaging in the same configuration example, and Figure 5 is a diagram showing an example of the shape of the chopper in the same configuration example.
The figure is an explanatory diagram with the irradiation light applied to the central part of the fiber diffraction grating, Figure 6 is an explanatory diagram with the irradiation light applied to the end of the diffraction grating, and Figures 7 and 8 are the illustrations shown in Figures 5 and 6, respectively. FIG. 9 is an explanatory diagram of an example of a captured image of a projection pattern corresponding to
10 is a diagram showing an example of an image photographed by a vertical striped pattern of projection light, FIG. 11 is a diagram showing an example of one photographic surface by spot light, and FIG. 12 and FIG. Figure 13 is a diagram of the relationship between the tip of the endoscope and the subject.
FIGS. 14 and 15 are explanatory diagrams of the structure of the fiber diffraction grating and the state of spot light generation. 1... Light source 2... Pattern projection light source 3... Scope 4... Camera control unit 5...
・Decoder 6...A/D 7...Frame memory 8...D/A 9...Monitor 10...A
/D 11... Uniform image memory 12... Enhanced image memory 13... Reference level generation section 14... Comparison section 15... Binarization processing section 16... Thinning processing section 17...・Spot center detection section 18... Calculation section
One... Output processing section 20... Lens 21...
Endoscope scope tip 22...imaging element 23...
- Diffraction grating 24... Subject 25... Spot light 26.27...-dimensional fiber diffraction grating 26a, 2
7a...Glass fiber 28...Oscillator 2
9...Laser light

Claims (1)

[Claims] (1) In a measurement endoscope device that projects illumination light having a two-dimensional regular pattern onto a subject and recognizes the unevenness of the subject from the distortion of the pattern on an image of the reflected light, the pattern uniform light irradiation means that generates irradiation light with a substantially uniform amount of light over the entire area; and emphasis light irradiation means that generates irradiation light that emphasizes only a specific part of the pattern by increasing the amount of light than other parts; A measurement endoscope apparatus comprising: an irradiation switching means that temporally alternately switches and irradiates both the irradiation light from the emphasized light irradiation means and the uniform light irradiation means.