JP3000320B2 - Deep observation endoscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope for observing an inner surface of a body cavity of a living body, and more particularly to a deep observation endoscope capable of observing not only the inner surface of the body cavity but also a deeper portion than the surface. is there.

[0002]

2. Description of the Related Art Conventionally, a fiber scope using an optical fiber has been known as an endoscope for observing the inside of a specimen, that is, the inner surface of a body cavity of a living body.

In the fiber scope, an illumination light source and an image input means are disposed at one end of a flexible optical fiber, and an image input to the image input means is transmitted to the other end of the flexible optical fiber. Image output means for outputting to the outside through the one end is inserted into the body cavity, the illumination light emitted from the illumination light source is reflected on the inner surface of the body cavity, and the image by the reflected light is The image is input to the image input means and output from the image output means via an optical fiber extending to the outside of the body cavity, thereby observing the inner surface of the body cavity outside the body cavity in real time.

The fiber scope can perform not only the above-described real-time observation, but also a biopsy using a forceps channel and a treatment using electricity, microwaves, laser light, and the like. I have.

On the other hand, there is an electronic endoscope as an endoscope which makes full use of electronic technology and image processing technology which have been remarkably developed in recent years.

The electronic endoscope converts an endoscope image into an electric signal by using the image input means as a CCD in the fiber scope, and outputs the electric signal by an image output means via a transmission medium. Is used to reconstruct an image.

As described above, the electronic endoscope is excellent in communication and image processing such as filing and transfer of an image since an endoscope image can be captured as an electric signal.

[0008]

With the recent improvement in the technology of transendoscopic treatment and diagnosis, it is required that the endoscope collects various information.

[0009] For example, if aspect information of the lower layer part of the digestive organ mucosa can be collected, a lesion that cannot be seen from the surface can be found, so that early treatment by early detection can be expected.

However, in the conventional endoscope, the visible surface in the body cavity is simply observed by the reflected light, and it is not possible to obtain the required deep information in the body cavity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a deep observation endoscope capable of observing not only the surface inside a body cavity but also the shape of a deep part in view of the above circumstances.

[0012]

According to a first aspect of the present invention, there is provided a deep observation endoscope having an incident end through which light is incident, and an exit end through which the incident light exits. A flexible fiber bundle inserted into the specimen to be observed, a light source that causes light to enter the incident end of the fiber bundle, and light emitted from the exit end of the fiber bundle to the inside of the specimen. And an image forming means for obtaining a two-dimensional image of the inside of the specimen, wherein the light source comprises a frequency-swept single-frequency laser light source, and the image forming means is reflected by the inside of the specimen. The frequency at which the intensity repeats due to the difference in the depth inside the reflected sample by interfering the light and the light that has traveled a constant optical path length by dividing a part of the light before being reflected by the sample Image signal mixed with various difference frequency beat signals The obtained image signal forming means and the image reproducing means for reproducing an image of the reflecting surface of the specimen at a predetermined depth by separating and reproducing a difference frequency beat signal that repeats strength and weakness at a predetermined frequency from the image signal. It is characterized by becoming.

Further, the deep observation endoscope according to claim 2 is
2. The deep observation endoscope according to claim 1, wherein the image signal forming unit divides light before being incident on an incident end of the fiber bundle into two light beams whose polarization planes are substantially orthogonal to each other. First wavefront matching means for wavefront matching the two lights split by the optical path splitting means before being incident on the incident end of the fiber bundle, and wavefront matching emitted from the emission end of the fiber bundle. Second wavefront matching means for splitting the light into two lights whose polarization planes are substantially orthogonal to each other, and for wavefront matching the light that has been split and travels a fixed optical path length with the light reflected by irradiating the specimen. And polarization means for causing components in the same polarization direction of two lights wavefront matched by the second wavefront matching means to interfere with each other; and various kinds of difference frequency beat signals having different frequencies at which the intensity obtained by the interference is repeated. Detect 2 A frequency analysis means for separating a difference frequency beat signal that repeats strength at a predetermined frequency from the various difference frequency beat signals, and a strength analysis at the predetermined frequency. It is characterized by comprising reconstructing means for reconstructing an image of a specific deep portion of the sample from the difference frequency beat signal, and image output means for outputting an image reconstructed by the reconstructing means.

Further, in the deep observation endoscope according to the third aspect, in the deep observation endoscope according to the second aspect, the second wavefront matching means, the polarization means, and the two-dimensional light intensity detection means are integrated. And rotating means for rotating about an axis substantially parallel to an optical path of light emitted from the emission end.

According to a fourth aspect of the present invention, in the deep observation endoscope according to the first aspect, the fiber bundle comprises a single mode image fiber bundle,
Scanning means for sequentially irradiating the frequency-swept single-frequency laser light to the input ends of a plurality of fibers constituting the image fiber bundle, and the image signal forming means being arranged in an optical path of the image fiber; The laser light incident from the incident end of the optical fiber is divided into light that travels a constant optical path length and light that exits from the exit end of the image fiber, and the light that travels the constant optical path length and the image fiber A fiber interference system that interferes with light emitted from the specimen and reflected by the specimen and incident on the image fiber again from the emission end, and various kinds of difference frequency beat signals having different frequencies that repeat the strength obtained by the interference are output. And a two-dimensional light intensity detecting means for detecting a predetermined frequency from the various difference frequency beat signals. Frequency analysis means for classifying a difference frequency beat signal repeating strength and strength, reconstructing means for reconstructing an image of a specific deep portion of the specimen from the difference frequency beat signal repeating strength and strength at the predetermined frequency, and reconstructing means by the reconstruction means. Image output means for outputting the configured image.

[0016]

In the deep observation endoscope according to the present invention, a frequency-swept single-frequency laser light source emits laser light whose frequency is temporally swept, and the emitted laser light is emitted from the incident end of the fiber bundle. The fiber bundle enters the fiber bundle and is inserted into the specimen. The fiber bundle is emitted from the exit end of the fiber bundle to irradiate the inside of the specimen.

At this time, the laser light emitted from the laser light source is emitted before irradiating the inside of the sample, that is, immediately after being emitted from the laser light source, in the fiber bundle, or immediately after emitted from the fiber bundle. The laser beam is divided so that a part of the laser beam does not irradiate the inside of the sample and travels a constant optical path length.

On the other hand, the laser beam emitted from the exit end of the fiber bundle and irradiating the inside of the specimen is reflected by the surface inside the specimen and several layers of reflecting surfaces in the deep part, and the surface and the deep part inside the specimen are reflected by the image forming means. The plurality of laser beams reflected by the multiple reflecting surfaces and the laser beams traveling along the divided constant optical path length interfere with each other.

Here, the laser light reflected by the surface inside the specimen or the deep reflecting surface has a different optical path length depending on the difference in the depth to the reflected reflecting surface, that is, reaches the image forming means. The time it takes to do so varies.

At this time, since the frequency of the laser light source is temporally swept, when the laser light reflected by the different reflecting surfaces inside the specimen reaches the image forming means,
The frequency of the laser light that has traveled a fixed optical path length is determined from the difference between the optical path lengths of the two laser lights and a function of the frequency with respect to the time of the frequency sweep.

As described above, the frequency of the laser light that travels a constant optical path length and reaches the image forming means is different from the frequency of the laser light that is reflected by a different reflection surface inside the sample and reaches the image forming means. Therefore, when these two laser lights are interfered by the image forming means, a difference frequency beat signal is generated due to the difference between the frequencies of these two laser lights.

As described above, various frequencies of the difference frequency beat signal are generated due to the difference in the depth of the reflection surface inside the specimen. The laser beam reflected at a predetermined depth inside the sample is selected by separating the difference frequency beat signal having a predetermined frequency from the various difference frequency beat signals having different frequencies generated by the image reproducing means. In addition, light absorption information of the specimen at that depth can be obtained from the intensity of the reflected laser light. Therefore, a two-dimensional planar image of a predetermined deep portion is obtained from the reflected light by the image reproducing means.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a deep observation endoscope according to the present invention. The illustrated endoscope includes a frequency-swept single-frequency laser light source 1 and a single-mode fiber that emits laser light from an emission end inserted into a body cavity with laser light emitted from the laser light source 1 incident on an incidence end. 3 is provided.

Here, the laser light source 1 and the fiber 3
Between the half-wave plate 4 and the polarizing beam splitter 5 for dividing the laser beam a ₁ emitted from the laser light source 1 into two laser beams a ₂ and a ₃ whose polarization planes are substantially orthogonal to each other. Optical path dividing means, and the two laser beams a ₂
And a polarization beam splitter 6 is disposed to a ₃ as the wavefront matching means for wavefront matching on the same axis.

The laser beam a ₅ guided to the specimen 2 in the body cavity through the single mode fiber 3 is split into two laser beams a ₆ and a ₇ whose polarization planes are substantially orthogonal to each other. one of a polarizing beam splitter 7 and two quarter-wave plate 9, 9 'the laser beam a ₆ and a ₇ as the second wavefront matching means for again WFM,
The laser beam a ₆ is split into the optical path by the polarizing beam splitter 7 and travels along one of the optical paths.
A mirror 8 for maintaining a constant optical path length of ₆ is provided.

Further, the components of the same polarization direction of the two laser beams a ₆ and a ₇ whose polarization planes are substantially orthogonal to each other and whose wavefronts are matched by the polarization beam splitter 7 are allowed to pass through to interfere with each other. a polarizing plate 10, and a parallel operation type image sensor 11 for detecting the difference frequency beat signal of a wide laser beam a ₈ which is the interference is formed.

Further, a parallel frequency analyzing means 12 for separating a difference frequency beat signal which repeats strength and weakness at a predetermined frequency from various kinds of difference frequency beat signals obtained by the parallel operation type image sensor 11, The apparatus includes a reconstructing unit 13 for reconstructing a plane image or the like of a specific deep portion of the specimen 2 from the intensity of the frequency beat signal, and an image output unit 14 for visually outputting the reconstructed plane image or the like.

Next, the operation of this embodiment will be described.

As shown in FIG. 2, a laser beam a ₁ whose frequency is swept in a triangular wave form is emitted from the laser light source 1, and the laser beam a ₁ is polarized by a half-wave plate 4 and a polarizing beam splitter 5 at the next stage. Are substantially orthogonal, and are divided into _two laser beams a ₂ and a ₃ traveling in two optical paths.

The two divided laser beams a ₂ and a ₃ are subjected to wavefront matching by the polarization beam splitter 6.

The laser light a ₄ whose wavefront has been matched is applied to the lens 15.
And enters the single mode fiber 3, propagates inside the fiber 3, and is guided into the body cavity.

The laser light guided into the body cavity is a lens
16 is a parallel light a ₅ by, is divided into the laser beam a ₇ for irradiating the specimen 2 by the polarization beam splitter 7 and the laser beam a ₆ traveling a predetermined optical path length.

After the laser beam a ₆ traveling the above-mentioned constant optical path length passes through the reflection surface of the polarizing beam splitter 7,
The polarized beam splitter 7 is reflected by the mirror 8
Is reflected by the reflecting surface of This is because while the laser beam a ₆ reciprocates between the polarizing beam splitter 7 and the mirror 8,
/ 4 polarization plane of the laser beam a ₆ for the wavelength plate 9 to pass twice because that is rotated 90 °.

On the other hand, the laser beam a ₇ irradiating the specimen 2 is reflected by each of the reflective surfaces L ₁ , L ₂ , L ₃ , L ₄ of the specimen 2, and the respective reflected lights are reflected. The process proceeds to the polarization beam splitter 7.

[0036] The respective reflection surfaces L ₁ of the sample 2 laser beam a ₇ emitted from the polarization beam splitter 7 at this time is from the outgoing the polarization beam splitter 7, ..., the polarization beam is reflected by the L ₄ The time required to reach the splitter 7 depends on the depth of each reflection surface of the specimen 2.

A plurality of reflected laser beams obtained by being reflected by the respective reflecting surfaces L ₁ , L ₂ , L ₃ , and L ₄ are sequentially wavefronted by the polarizing beam splitter 7 with the laser beam traveling through the above-mentioned constant optical path length. The frequency of the laser light that has been matched, but has traveled a constant optical path length in which the plurality of reflected laser lights are wavefront matched depends on the depth of each of the reflective surfaces and changes continuously according to the frequency sweep waveform shown in FIG. ing.

As described above, the laser light sequentially wavefront-matched passes through the polarizing plate 10, and the same polarization direction components of the two laser lights before wavefront matching interfere with each other. A difference frequency beat signal that repeats strength and strength at a frequency corresponding to the difference between the frequencies of the two laser beams is generated. Various kinds of difference frequency beat signals are generated such that the intensity repeats at different frequencies for each of the reflection surfaces L ₁ , L ₂ , L ₃ and L ₄ . Furthermore, the above-mentioned various kinds of difference frequency beat signals are detected by the parallel operation type image sensor 11, and the parallel frequency analysis means 12 repeats the difference frequency beat signal at a specific frequency, that is, the specimen reflected at a specific depth of the specimen. The light absorption information at a specific depth of Further reconstruction means
13 to calculate the depth of the sample from the frequency of the difference frequency beat signal of the specific frequency, obtain the light absorption information of the sample 2 from the detection intensity of the difference frequency beat signal, and determine the depth position of the sample. Image output means for reconstructing a planar image
By 14, the plane image is visually output.

Further, the parallel frequency analysis means 12
If all the difference frequency beat signals are separated and the depth and light absorption information of the specimen 2 are calculated by the reconstructing means 13, a tomographic image of the observed part of the specimen 2 can be obtained.

FIG. 3 is a block diagram showing a second embodiment of the present invention. The illustrated endoscope includes a frequency-swept single-frequency laser light source 1 and a single light source that emits laser light emitted from the laser light source 1 from an incident end and emits the laser light from an emission end inserted into a body cavity. And a mode image fiber 23.

Further, between the laser light source 1 and the single-mode image fiber 23, a laser for emitting the laser light emitted from the laser light source 1 sequentially to the incident ends of a plurality of fibers constituting the image fiber 23. Optical scanning means 24 is provided.

Further, the laser beam incident from the incident end of the image fiber 23 is split into light for traveling a predetermined optical path length and light emitted from the output end of the image fiber 23, The light that has traveled the optical path length is emitted from the image fiber 23, is reflected by the sample 22, and is returned from the emission end to the image fiber.
A fiber interference system 25 is provided that causes the reflected light incident on the fiber 23 to interfere with the reflected light and emit the reflected light from the fiber 23.

Further, an image sensor 26 for detecting various kinds of difference frequency beat signals of the interfering laser light emitted from the fiber interference system 25 is provided.

Further, a time-series frequency analyzing means 27 for classifying a difference frequency beat signal which repeats strength at a predetermined frequency from the various difference frequency beat signals, and a sample 22 based on the difference frequency beat signal repeating strength and strength at the predetermined frequency. A reconstructing means 13 for reconstructing an image at a specific deep portion of the image forming apparatus, and an image output means 14 for outputting an image reconstructed by the reconstructing means 13.

Next, the operation of this embodiment will be described.

As shown in FIG. 2, a laser light whose frequency has been swept in a triangular wave form is emitted from the laser light source 1, and the emitted laser light is incident on a plurality of fiber bundles constituting the image fiber 23 by a scanning means 24. Are sequentially guided.

The laser light guided to the image fiber 23 travels inside each fiber bundle, and the fiber interference system 25
As a result, the laser beam is split into a laser beam that travels a fixed optical path length and a laser beam that travels to the exit end of the fiber bundle.

FIG. 4 is a simplified view in which a part of a plurality of fiber bundles constituting the image fiber 23 is emphasized for explanation of the operation.

That is, the laser beam incident on the fiber 23a by the scanning means 24 is converted into a fiber interference system comprising a well-known optical coupler.
The laser beam 25 is divided into a laser beam traveling along an optical path (fiber 23b) for irradiating the specimen 22 and a laser beam traveling along an optical path (fiber 23c) having a constant optical path length.

The laser light traveling along the optical path (fiber 23b) for irradiating the specimen 22 is emitted from the exit end of the fiber 23b and is reflected by the surface of the specimen 22 or a multilayer reflective surface at a deep portion to form a plurality of reflected lights. The light enters the fiber 23b again from the exit end of the fiber 23b and reaches the fiber interference system 25.

On the other hand, an optical path having a constant optical path length (fiber 23c
) Is reflected by the mirror and reaches the fiber interference system 25, and the laser beam traveling along the optical path having the constant optical path length is determined by the time difference between the plurality of reflected lights reaching the fiber interference system 25. The frequency of the light changes continuously.

For this reason, when each of the reflected lights interferes with the laser light traveling along the optical path having a constant optical path length by the fiber interference system 25, various types of difference frequency beat signals having different frequencies that repeat strong and weak are generated. The various difference frequency beat signals are guided to the image sensor 26 by the fiber 23d.

By the same operation as described above, the image sensor 26 detects the various kinds of difference frequency beat signals in the order in which the scanning means 24 scans the image fiber 23.

Further, a predetermined difference frequency beat signal is discriminated from the difference frequency beat signals of various frequencies detected by the image sensor 26 by the time series frequency analysis means 27 synchronized with the scanning.

The operation of the reconstructing means 13 and the image output means 14 is the same as the action of the reconstructing means 13 and the image output means 14 in the embodiment shown in FIG.

The deep observation endoscope according to the present embodiment can observe a planar image or a tomographic image at an arbitrary deep part of the specimen 22 by the above-described operation.

FIG. 5 is a block diagram showing a third embodiment of the present invention. The illustrated deep observation endoscope comprises a polarizing beam splitter 7, quarter-wave plates 9 and 9 ', a mirror 8 and a polarizing plate 10 inserted into the body cavity in the embodiment shown in FIG.
1 except that a rotation means 100 for integrally rotating an optical system comprising a parallel operation type image sensor 11 and a lens 16 around an axis substantially parallel to an optical path emitted from the emission end is provided. The configuration is the same as that of the illustrated embodiment.

The operation of this embodiment is the same as that of the embodiment shown in FIG. 1 except that the rotating means 100 radially scans the lumen-shaped specimen 32 with the fiber 3 as the center. A total of 32 tomographic images can be obtained.

[0059]

As described in detail above, the deep observation endoscope of the present invention observes a deep part in a body cavity, which cannot be observed with a conventional endoscope, as a plane image or tomographic image of a specific depth. It is useful in that a deep lesion in a body cavity can be found at an early stage.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a deep observation endoscope according to the present invention.

FIG. 2 is a waveform diagram showing a frequency sweep waveform of a frequency sweep single frequency laser light source used in an embodiment of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the deep observation endoscope according to the present invention;

FIG. 4 is a simplified diagram of the second embodiment shown in FIG.

FIG. 5 is a block diagram showing a third embodiment of the deep observation endoscope according to the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Frequency sweep single frequency laser light source 2, 22, 32 samples 3 Single mode fiber 4 1/2 wavelength plate 5, 6, 7 Polarization beam splitter 8 Mirror 9, 9, 1/4 wavelength plate 10 Polarizer 11 Parallel operation type Image sensor 12 Parallel frequency analysis means 13 Reconstruction means 14 Image output means 23 Single mode image fiber 23a to 23d fiber 24 Laser light scanning means 25 Fiber interference system 26 Image sensor 27 Time series frequency analysis means 100 Rotation means

Claims (4)

(57) [Claims] 1. A flexible fiber bundle having an incident end through which light is incident and an exit end through which the incident light exits, the exit end being inserted into the inside of a specimen to be observed, A light source that causes light to enter the incident end of the fiber bundle; and image forming means that irradiates the inside of the specimen with light emitted from the exit end of the fiber bundle and obtains a two-dimensional image of the inside of the specimen. In the endoscope, the light source includes a frequency-swept single-frequency laser light source, and the image forming unit divides a part of the light reflected by the inside of the specimen and a part of the light before being reflected by the specimen to be constant. An image signal forming means for obtaining an image signal in which various kinds of difference frequency beat signals having different frequencies repeating strong and weak due to the difference in the depth of the reflected sample by interfering with the light having advanced the optical path length, A predetermined frequency from the image signal By performing the reproduction on the fractionating difference frequency beat signal varies in intensity, deep observation endoscope characterized by comprising the image reproducing means for reproducing the image of the reflecting surface of a predetermined depth of the specimen. 2. An image signal forming unit, wherein the image signal forming unit divides light before being incident on an incident end of the fiber bundle into two light beams whose polarization planes are substantially orthogonal to each other; First wavefront matching means for wavefront matching the two lights before being incident on the incident end of the fiber bundle, and the polarization plane of the wavefront matched light emitted from the emission end of the fiber bundle being substantially orthogonal. Second wavefront matching means for performing wavefront matching between the light that has been split and travels a predetermined optical path length and the light reflected by irradiating the specimen, and the second wavefront matching. Polarizing means for interfering components of the same polarization direction of two lights wavefront-matched by means, and two-dimensional light intensity detection for detecting various kinds of difference frequency beat signals having different frequencies of repeating strong and weak obtained by the interference. Means, A frequency analysis unit that classifies a difference frequency beat signal that repeats strength at a predetermined frequency from the various difference frequency beat signals; and a specification of the sample from the difference frequency beat signal that repeats strength at the predetermined frequency. 2. A deep observation endoscope according to claim 1, comprising: a reconstructing means for reconstructing a deep image, and an image output means for outputting an image reconstructed by said reconstructing means. 3. A rotation for integrally rotating the second wavefront matching means, the polarization means, and the two-dimensional light intensity detection means around an axis substantially parallel to an optical path of light emitted from the emission end. 3. The deep observation endoscope according to claim 2, further comprising means. 4. The fiber bundle comprises a single-mode image fiber bundle, and the image signal forming means causes the frequency-swept single-frequency laser light to sequentially enter incident ends of a plurality of fibers constituting the image fiber bundle. Scanning means, which is arranged in the optical path of the image fiber, splits laser light incident from the incident end of the image fiber into light that travels a constant optical path length and light that exits from the exit end of the image fiber. And a fiber interference system for interfering the light that has traveled the predetermined optical path length with the light emitted from the image fiber, reflected by the sample, and again incident on the image fiber from the emission end. Two-dimensional light intensity detecting means for detecting various kinds of difference frequency beat signals having different frequencies repeating the strength obtained by The image reproducing means, a frequency analysis means for separating a difference frequency beat signal that repeats strength at a predetermined frequency from the various difference frequency beat signals, and the difference frequency beat signal repeating strength and weakness at the predetermined frequency. 2. A deep observation endoscope according to claim 1, comprising: reconstructing means for reconstructing an image of a specific deep portion of the sample; and image output means for outputting an image reconstructed by the reconstructing means.