JP2001083077A - Optical-imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a light sectional image that is speedily continuous with improved S/N ratio in an OCT(optical coherent tomography) device with a replaceable probe. SOLUTION: An optical path length-varying mechanism 22 is composed of a light collimator 42 for converting into a beam shape, the light being emitted from a single-mode fiber 5, that is changed speedily by approximately several mm to detect scattering and reflection light from a specific range in the depth direction of an biological tissue, an acoustic optical deflector 43 for changing the direction of the light beam, a Fresnel lens 44 for allowing a light beam whose direction has been changed to be in parallel with the optical axis, a second Fresnel lens 46 for directing light in parallel with an optical axis 45 toward an acoustic optical deflector 47, the acoustic optical deflector 47 for allowing the light entering the acoustic optical deflector 47 to coincide with the light axis 45 again, a light collimator 48 for efficiently guiding light to a sixth signal-mode fiber, and a traveling stage, that can travel in the direction of the light axis being changed according to the length of the light-scanning probe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical imaging apparatus for irradiating a subject with light having low coherence and constructing a tomographic image inside the subject from information of light scattered and reflected on the subject.

[0002]

2. Description of the Related Art In recent years, in order to diagnose a lesion in a living tissue,
An OCT (optical coherent tomography) for constructing a tomographic image of the inside of a tissue using low interference light as a device for detecting and imaging the information inside the tissue by an optical method is disclosed in, for example, Japanese Patent Publication No. Hei 6-511213. Gazette, WO9
8/52021.

[0003] In Japanese Patent Application Laid-Open No. 6-511312, in order to detect scattered / reflected light from a specific depth of a living tissue, it is obtained by moving a reference mirror forward and backward. Further, in order to construct a tomographic image inside the living tissue, a tomographic image is constructed by scanning a light beam irradiating the living tissue and synchronizing the advance and retreat of the reference mirror.

On the other hand, WO98 / 52021 has several tens of K
An OCT device that can be driven at Hz has been proposed. WO9
In 8/52021, in order to detect scattered / reflected light from a specific depth of a living tissue, a light beam is spectrally decomposed by a diffraction grating or the like, and a galvanomirror or an AOM (Acoustic Optical Modulat) is used.
A method of changing the phase and the group velocity of the reference light by scanning the light beam with ions or the like is shown.

[0005]

However, in Japanese Patent Laid-Open Publication No. Hei 6-511312, a relatively heavy reference mirror is advanced and retracted by about 5 mm.
The driving is limited to about several tens Hz. For this reason, a continuous moving image cannot be obtained, and when diagnosing a living tissue, there is a problem of image quality deterioration due to blurring of an image due to movement of a heartbeat or the like.

In WO98 / 52021, low-interference light from a light source is split into two and guided to a subject and a reference arm. Furthermore, the reflected light from the subject and the reflected light from the reference arm are combined again,
A Michelson interferometer configured to receive the interference component with one photodetector is configured. The Michelson interferometer has a simple optical configuration, but has an S / N ratio because the interference light is received by one photodetector. Is low.

In the reference arm, the phase and group velocity are changed by displacing the mirror at a high speed with respect to the light beam. At this time, a Doppler shift occurs due to the phase change. Therefore, the interference signal can be detected with high sensitivity by optical heterodyne detection of the signal received by the photodetector.

However, in order to displace a galvanometer mirror or the like at high speed, it is necessary to drive the mirror with a sine function. In this case, the Doppler shift amount is displaced by a cosine function which is a derivative thereof, and furthermore, the optical heterodyne detection frequency fluctuates, so that the S / N is reduced or only a portion having a small displacement is detected, so that the efficiency is deteriorated. There was a problem.

The present invention has been made in view of the above circumstances, and provides an optical imaging apparatus capable of generating a high-speed continuous optical tomographic image with good S / N in an OCT apparatus capable of exchanging probes. It is intended to be.

[0010]

According to the present invention, there is provided an optical imaging apparatus for constructing a tomographic image of the subject by reflected / scattered light obtained by irradiating the subject with light having low coherence. A first light path means for guiding the low-coherence light from the light source to the subject and for guiding reflected / scattered light from the subject, and A first optical scanning means which is detachably connected to the first optical path means, guides the low coherence light to the subject, and can scan at least one-dimensionally; Light separating means for separating a part of the low coherence light from the light source and reflected / scattered light from the subject from the first light scanning means, and being separated by the light separating means; A second optical path means for guiding the light having low coherence, The reflection separated by means &
A third optical path means for guiding the scattered light, and a first optical path means for changing an optical path length provided on one of the second or third optical path means.
An optical path length adjusting mechanism having an optical path length changing means for adjusting an optical path length according to the optical path length of the first optical scanning means, and an optical path length adjusted by the optical path length adjusting mechanism. Coupling means for coupling the low-coherence light of the second optical path means and reflected / scattered light of the third optical path means to interfere with each other; and detection means for detecting interference by the coupling means as an interference signal. Image generating means for processing the interference signal detected by the detecting means to generate a tomographic image of the subject.

In the optical imaging apparatus according to the present invention, the coupling means adjusts the optical path length by the optical path length adjusting mechanism and reflects the low coherence light of the second optical path means and the reflection / reflection of the third optical path means. Coupling the scattered light and causing interference, the detection means detects the interference by the coupling means as an interference signal,
In the OCT apparatus capable of exchanging probes, the image generation unit performs signal processing on the interference signal detected by the detection unit to generate a tomographic image of the subject.
It is possible to generate a high-speed continuous optical tomographic image with good S / N.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows a configuration of an optical imaging apparatus according to a first embodiment of the present invention.

The optical imaging apparatus 1 according to the first embodiment
Is a low coherence light source 2 comprising a high-brightness light emitting diode (SLD), a broadband fiber light source, etc., and generating low interference light.
And a plurality of single mode fibers (3, 5, 2) arranged to transmit light and cause light interference.
8, 29), an optical system for guiding light into a living body, and a rotation driving device 7 and an optical scanning probe 6 for rotating and scanning low interference light, and a depth direction of the low interference light applied to the living body Optical path length variable mechanism 2 that changes the optical path length at high speed and minutely to detect the scattered / reflected light (return light) while changing the position
2, a photodetector (23, 24) for combining return light from the living body and low interference light (reference light) from the light source to convert the interference light into an electric signal, and a subtractor 31, and A signal processing circuit 32 for extracting a signal component corresponding to the return light intensity, a control device 35 for synchronizing the position of the return light in the depth direction of the optical path length variable mechanism 22 with the optical scanning position of the optical scanning probe 6, An image processing device 33 which detects a signal of the signal processing circuit 32 and forms an image while controlling the control device, and a monitor 34.

The low coherence light source 2 has a center wavelength of about 1300 nm and a coherence length of, for example, 10 to 2 nm.
It has a characteristic of low coherence that interferes only in a short distance range of about 0 μm.

That is, when this light is split into two light beams and recombined, the optical path difference interferes with each other within the range of the coherent distance, but does not interfere outside the range.

The low interference light from the low coherence light source 2 enters one end of the first single mode fiber 3 and is transmitted to the other end face. The first single mode fiber 3 is optically coupled to the second single mode fiber 5 by the first optical coupler 4 in the middle of the first single mode fiber 3.

That is, the first single mode fiber 3
A part of the light transmitted inside is transmitted to the second single mode fiber 5 by the first optical coupler unit 4.

A part of the low interference light that has passed through the first optical coupler 4 is transmitted to the distal end of the first single mode fiber 3 as it is, and is transmitted to the distal end of the optical scanning probe 6 via the rotation driving device 7. The living tissue 8 is irradiated while rotating and scanning from the part. The rotation driving device 7 drives the rotation scanning of the optical scanning probe 6.

The low-interference light applied to the living tissue 8 is reflected and scattered on the surface and inside of the tissue, and a part of the returned light returns to the first single mode fiber 3 via the opposite optical path. A part of the return light returning to the first single mode fiber 3 is transmitted to the second single mode 5 side by the first optical coupler unit 4 and arranged on the base end side of the second single mode fiber 5. Then, the light enters the phase modulation element 20.

The return light incident on the phase modulation element 20 is
Due to the Doppler effect caused by driving the phase modulation element 20 at a high speed (for example, 20 MHz), the frequency of light is shifted by about several tens KHz to several hundred MHz, and transmitted to the fifth single mode fiber 28.

On the other hand, part of the low-interference light input from the low-interference light source 2 to the first single-mode fiber 3 is transmitted to the second single-mode fiber 5 by the first coupler 4. This light is called reference light.

An optical path length variable mechanism 22 is connected to the other base end of the second single mode fiber 5, and the reference light is transmitted to the optical loop section 21 on the way, and is incident on the optical path length variable mechanism 22. Is done.

The reference light incident on the variable optical path length mechanism 22 changes its optical path length according to the length of the optical scanning probe by the variable optical path length mechanism 22 and at the same time, in the depth direction of the living tissue, that is, in the optical axis direction. In order to detect scattered / reflected light from a specific range, after changing it several mm at high speed,
The light is transmitted to the sixth single mode fiber 29.

The loop section 21 is set so that the optical paths of the return light and the reference light incident on the first and second detectors 23 and 24 are substantially equal.

The return light and the reference light transmitted to the fifth and sixth single mode fibers 28 and 29 are:
The light is combined / branched again by the second optical coupler unit 30, is incident on the first and second photodetectors 23 and 24, and is converted into an electric signal. At this time, the first and second detectors 23 and 24
The light components having the same optical path lengths of the return light and the reference light incident on each other interfere with each other.

Further, the first and second photodetectors 23, 2
4 is connected to a differentiator 31 to cancel the offset component of light, that is, the DC component other than the interference signal,
By detecting the frequency difference (beat signal) modulated by the phase modulation element 20 by the signal processing circuit 32, an electric signal corresponding to the return light can be extracted with high sensitivity.

A method of canceling a DC component by using two photodetectors and a differentiator is well known as balance detection. A method of modulating one light (here, return light) by a phase modulation element and taking a beat to improve detection sensitivity is well known as optical heterodyne detection.

The electric signal corresponding to the return light is constructed as a tomographic image by the image processing device 33 and displayed on the monitor 34.

In order to construct a tomographic image, it is necessary to know the position of the return light accurately. For this reason, the control device 35 controls the variable optical path length mechanism 22 and the rotary driving device 7 to adjust the position of the return light.

FIG. 2 is a configuration diagram showing the configuration of the optical scanning probe 6 and the rotary driving device 7. As shown in FIG. 2, in the rotation driving device 7, an optical rotary joint 9 for coupling the first single mode fiber 3 and the third single mode fiber 10 so that light can be transmitted between a non-rotating portion and a rotating portion. Are connected by The third single mode fiber 10 is connected to a fourth single mode fiber 12 disposed in the optical scanning probe 6 by an optical connector 11.
And optically coupled.

An optical unit 13 containing a GRIN (GRadient INdex) lens and a prism is optically coupled to the tip side of the fourth single mode fiber 12, and the low interference light is transmitted in the axial direction of the optical scanning probe 6. Irradiated perpendicularly.

On the other hand, the rotating part of the optical rotary joint 9 has a motor 15 and an encoder 16 rotatably connected via a belt 17. Further, a rotating shaft 14 is coupled to a rotating portion of the optical rotary joint 9, and transmits a rotating force to the transmission connector 18 and the flexible shaft 19. The optical unit 13 is joined to the tip of the flexible shaft 19.

That is, by rotating the motor 15, the rotating portion of the optical rotary joint 9 and the rotating shaft 1 are rotated.
4 rotates, and this rotational force is transmitted to the transmission connector 18 and the flexible shaft 19, and the optical unit 13 integrated therewith can be rotationally scanned.

Since the encoder 16 generates a signal corresponding to the rotational position and speed, the rotary drive controller 2
Reference numeral 7 receives a signal from the encoder, and controls the motor 15 so that the rotational position and the speed have specific values.

The transmission connector 1 of the optical scanning probe 6
8, the flexible shaft 19 and the optical unit 13 are covered with a connector cover 25 and an optically transparent sheath 26.

FIG. 3 is an explanatory view in which the optical scanning probe of FIG. 1 is used in combination with an endoscope. The optical scanning probe 6 according to the first embodiment includes an endoscope 36 as shown in FIG.
Through the forceps insertion channel 37 through the forceps insertion channel, and from the distal end opening near the distal end portion 38 of the endoscope.

The endoscope 36 has an elongated insertion portion 39 so that it can be easily inserted into a body cavity. An operation portion 40 is provided at the rear end of the insertion portion 39, and is disposed on the operation portion 40. By moving an operation lever (not shown), the bending angle of the bending portion 41 on the distal end side of the insertion portion can be controlled. That is, as shown in the figure, the bending portion 4 of the endoscope 36 is operated by the operation lever.
By manipulating the bending angle of 1, the optical scanning probe 6
Place in close proximity to

FIG. 4 is a configuration diagram showing the configuration of the optical path length varying mechanism of FIG. As shown in FIG.
Is to change light emitted from the second single-mode fiber 5 into a beam, which changes at high speed by several mm to detect scattered / reflected light from a specific range in the depth direction of the living tissue, that is, in the optical axis direction. An optical collimator 42, a first acousto-optic deflector 43 for changing the direction of the light beam, and a first Fresnel lens 44 for making the light beam whose direction has been changed parallel to the optical axis 45. A second beam for directing light parallel to the optical axis 45 to the second acousto-optic deflector 47.
Lens 46 and the second acousto-optic deflector 4
A second acousto-optic deflector 47 for aligning the light incident on the optical axis 45 with the optical axis 45 again; a second optical collimator 48 for efficiently guiding the light to the sixth single mode fiber 29; A moving stage 49 that can be moved in the optical axis direction to be changed according to the length of the scanning probe.

Here, the Fresnel lenses 44 and 46 are thin lenses made of many ring-shaped prisms.

The second single mode fiber 5, the first optical collimator 42, the first acousto-optic deflector 43, and the Fresnel lens 44 are fixed to the moving stage 49, and move integrally. That is, the change in the optical path length due to the difference in the length of the optical scanning probe is adjusted by the moving stage 49.

FIG. 5 shows the details of the acousto-optic deflectors 43 and 47. An acousto-optic deflector is an optical element that induces a change in the refractive index by applying ultrasonic waves to a substance, and controls the direction of a light beam from a phenomenon in which light is diffracted. The acousto-optic deflector 43 (47) includes a transducer 43a made of LiNbO3 or the like that generates ultrasonic waves, an optical material 43b made of fused quartz, tellurite glass, gallium phosphide, indium phosphide, or the like, and a sound absorbing material 43c. . For example, when the light beam 43d is incident on the optical material 43b and the ultrasonic wave f1 is applied to the transducer 43a, the first-order diffracted light 43e is generated due to the change in the refractive index generated in the optical material 43b, and the first-order diffracted light θ1 is It is expressed by an equation.

Θ1 = λ0 × f1 / v (1) where λ0 is the wavelength of light in a vacuum, f1 is the ultrasonic frequency, and v is the speed of sound.

When the ultrasonic frequency is further changed by Δf from f1, the displacement angle Δθ becomes Δθ = λ0 × Δf / v (2).

The change in the optical path length will be described with reference to FIG. As shown in FIG. 6, the acousto-optic deflector 43 and the Fresnel lens 44 are arranged so as to have the focal length L of the Fresnel lens 44, and the optical path length a when the acousto-optic deflector 43 deflects from the optical axis 45 by θ2. The difference from the optical path length b when deflected by Δθ than θ2 is as follows: ba = L / cos θ2−L / cos (θ2 + Δθ) (3)

That is, the second single mode fiber 5
Is converted into a beam by the first optical collimator 42, and the direction of the light beam is changed by the first acousto-optic deflector 43. Furthermore, by making the light beam whose direction has been changed by the first Fresnel lens 44 parallel to the optical axis 45, an optical path length change corresponding to the equation (3) occurs.

In the present embodiment, the light is guided to the sixth single mode fiber 29 by the action opposite to that described above. In this case, the change in the optical path length is twice that of the equation (3). At this time, changes in the optical path length when light is scanned under the following conditions are as shown in FIG.

V = 5.1 km / s λ0 = 1.3 μm L = 20 cm Δf = 300 MHz / 15 μs (for example, changing the frequency in a sawtooth waveform) θ2 = 0 °, that is, when light is scanned from the optical axis 45, The optical path changes as shown in FIG. 7A, and when the light is scanned with an offset of θ2 = 7 ° with respect to the optical axis 45, the optical path changes as shown in FIG. 7B. θ2
The displacement of the optical path length when = 0 ° is about 1.2 mm, whereas the displacement of the optical path length when θ2 = 7 ° is 5 mm.

On the other hand, the change in the optical path length is more constant when θ2 = 7 ° than when θ2 = 0 °. That is, by giving an offset such as θ2 = 7 °, a large displacement of the optical path length and a linear displacement can be obtained, and a good interference signal can be obtained. Therefore, in the present embodiment, θ2 is set to 7 °.

As described above, in this embodiment, only the frequency of the ultrasonic wave input to the acousto-optic deflectors 43 and 47 is changed, and it can be driven at a higher speed than a conventional mechanical scanning means such as a motor. Can be generated with good S / N.

Further, the linearity of the optical path length change is high and the efficiency is high. In the conventional sin drive, near 90 ° and 270 °, the nonlinearity of the optical path length is high, which causes a reduction in efficiency and a reduction in S / N.

FIG. 8 is a block diagram showing a first modification of the electro-optical deflectors 43 and 47 as the optical scanning means in FIG.

The electro-optical deflector 148 according to the first modification includes:
Like the acousto-optic deflectors 43 and 47, the optical element is capable of changing the direction of light. A similar effect can be obtained by disposing an electro-optic deflector 148 in the optical path length variable mechanism 22 instead of the acousto-optic deflectors 43 and 47.

As shown in FIG. 8, the electro-optic deflector 148 has electro-optic crystals 149 and 150 attached to each other with their optical axes opposite to each other, and electrodes 151 and 152 are attached to the upper and lower sides. When light having a light beam diameter D is incident on the electro-optic crystal 149 side and an applied voltage V is applied to the electrodes 151 and 152, a change in the refractive index Δn occurs between the electro-optic crystals 49 and 50, and as a result, the optical axis becomes Displaced by Δθ.

The following relational expression exists between Δθ and the distance L between the electro-optic crystal and the light beam diameter D. Δθ = sin ⁻¹ (2ΔnL / D) (4) Here, Δn changes according to the applied voltage V. That is, by changing the applied voltage V, the direction of light can be changed.

FIG. 9 shows a hologram scanner 5 of a second modification of the electro-optical deflectors 43 and 47, which are the optical scanning means in FIG.
FIG. The hologram scanner 53 is an optical element that can change the direction of light, similarly to the acousto-optic deflectors 43 and 47. FIG. 9A is a diagram of the hologram scanner 53 viewed from the lateral direction.
9B is a diagram viewed from the direction B in FIG. 9A, that is, from above, and FIG. 9C is a diagram viewed from the direction C in FIG. 9A, that is, from the right.

As shown in FIG. 9, in a hologram scanner 53 of a second modification, a plurality of hologram elements 55 are arranged concentrically on a rotating disk 54, and the rotating disk is rotated by a motor 56. When the light beam 57 is incident on the hologram element 55, the light beam 57 changes its direction like the light beam 58 due to the diffraction effect. Further, when the rotating disk is rotated by the motor 56, the light beam is shifted from the light beams 58 to 5 corresponding to the incident position of the hologram element 55.
9, the angle can be changed. A linear grating and a hologram lens can be used as the hologram element.

The hologram scanner 5 of the second modified example
3 is cheaper than an acousto-optic device or an electro-optic device.

FIG. 10 shows a first example of the variable optical path length mechanism 22 of FIG.
It is a block diagram which shows the modification of. Here, portions different from the optical path length variable mechanism 22 will be described, and the same portions will be denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 10, the variable optical path length mechanism 60 of the first modification of the variable optical path length mechanism 22 includes first and second convex lenses 6 instead of the Fresnel lenses 44 and 46.
1, 62 are arranged. Further, a stepped optical block 63 is arranged between the first and second convex lenses 61 and 62.

As shown in FIG. 11, the optical block 63 is formed by bonding a micro prism array 64 and a triangular prism 65 together. For example, a micro prism array has a refractive index n = 1.5, an angle θ = 9.5 °, and a pitch p =
It has 200 prisms of 0.3 mm arranged side by side. The triangular prism 65 has a refractive index n = 1.5 and a length 1 = 6.
0 mm and thickness d = 10 mm.

The light emitted from the single mode fiber 5 is converted into a light beam having a diameter of about 0.2 mm by the first optical collimator 42, and the direction of the light beam is changed by the first acousto-optic deflector 43. Further, the light beam whose direction has been changed by the first convex lens 61 is made parallel to the optical axis 45. Further, the parallel light is transmitted through the optical block 63.

At this time, when light is scanned on the optical block 63 by the first acousto-optic deflector 43 as in the optical path 66, the optical path length changes in accordance with the scanning position.

For example, the optical path difference of the light transmitted through the positions 66a and 66b is the optical path difference transmitted through the optical block.
It is a refractive index difference, and in the above case, d × (n−1.0) = 6.
0 × (1,5-1,0) = 5 mm, and the resolution is 25 μm per pitch from 200 prisms. Further, the light transmitted through the optical block 63 is transmitted to the second convex lens 6.
The light enters the second acousto-optic deflector 47 at one point and is guided to the sixth single mode fiber 29 similarly to the optical path length variable mechanism 22 (see FIG. 10).

The pitch of the optical block, the number of prisms,
The length and thickness are not limited to these values, and the resolution and the scanning range can be changed by changing these values.

In the variable optical path length mechanism 66 of the first modification of the variable optical path length mechanism 22, the maximum optical path difference can be easily changed by changing the optical block.

(Second Embodiment) FIG. 12 shows a second embodiment of the present invention.
The configuration of the optical path length varying mechanism according to the embodiment is shown.
Will be described, and the same portions will be denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 12, the optical path length varying mechanism 67 of the present embodiment has a first cylindrical lens 68 for fanning out the light emitted from the second single mode fiber 5 and the fan-like spreading. The second to make the light parallel
, A rotatable rotating disk 70 having a plurality of elongated slit holes 71a-71h (see FIG. 13) that transmit a part of the parallel light 72 and turn into a light beam 73, and an optical block. 63 and the light beam 7
A third cylindrical lens 74 for causing the third light 3 to enter the sixth single mode fiber 29 and a second collimator 48 are provided.

The first cylindrical lens 68 is formed by bonding convex and concave cylindrical lenses in a 90 ° direction so as to convert light into a thin fan shape.

First, the light emitted from the second single-mode fiber 5 is fan-shaped by a first cylindrical lens 68 and further expanded by a second cylindrical lens 6.
At 9, the fan-shaped spread light is changed to parallel light 72.

As shown in FIG. 13, the rotary disk 70 has a plurality of long slit holes 71a-71h. When the rotary disk 70 is rotated, the slit holes cross the parallel light 72. As a result, the light transmitted through the rotary disk 70 is converted into a light beam 73, and the light beam 73 is converted into an optical block 6 by the rotation angle.
3 can be scanned.

For example, the slits of the rotating disk 70 are about 0.1 mm in width and about 10 mm in length, and eight slits are radially arranged at equal intervals. This rotating disk is
Rotating at 000 rpm allows 3200 scans / sec.

In the case where one screen is composed of 512 scanning lines, the rate is 6.25 screens / sec. The width, length, number of slits, and number of rotations of the rotating disk are not limited to these values, and the scanning speed can be changed by changing these values.

The light beam 73 scanned at high speed in this manner
Is transmitted through the optical block 63, and the optical path changes according to the incident position. Further, the beam light 73 is guided to the sixth single mode fiber 29 by the cylindrical lens 74 and the second collimator 48.

FIG. 14 is a block diagram showing a modification of the rotary disk shown in FIG. A plurality of minute bin holes 76 are formed in the second rotating disk 75, and the holes
2, the position is shifted. In other words, by rotating the second rotating disk 75, FIG.
Light can be scanned like the light beam 73 of FIG. Such a rotating disk is commonly known as a Nipkow disk.

As described above, in this embodiment, expensive components such as an acousto-optic deflector are not required, and the light scanning range is wide and the resolution can be increased. ).

(Third Embodiment) FIG. 15 shows a third embodiment of the present invention.
FIG. 4 is a configuration diagram showing a configuration of an optical path length variable mechanism according to the embodiment. Here, portions different from the optical path length variable mechanism 22 will be described, and the same portions will be denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 15, the variable optical path length mechanism 77 of the present embodiment comprises a first collimator 42 for converting light emitted from the second single mode fiber 5 into a light beam 78, Third rotating disk 79 to which optical blocks 63a to 63d equivalent to the block 63 are fixed.
(See FIG. 16).

In this embodiment, the light beam 78 does not change and is always on the optical axis. When the optical blocks 63a to 63d cross the beam light, the optical path length can be changed.

In this embodiment, an example is shown in which four optical blocks are arranged. However, by increasing the number of blocks, the number of scanning lines per rotation of the rotating disk can be increased.

As described above, in this embodiment, an expensive component such as an acousto-optic deflector becomes unnecessary, and the S / N can be increased without a decrease in the light intensity of the light beam.

[Appendix] (Appendix 1) An optical imaging apparatus which irradiates the subject with light having low coherence and constructs a tomographic image of the subject from information on reflected / scattered light reflected / scattered from the subject. A light source that generates the low-interference light, a first optical path unit that guides light from the light source to the subject, and the low-interference light that is connected to the first optical path unit and receives the low-interference light. An optical scanning probe that guides light to a sample and is at least one-dimensionally scannable and detachable, and a light separation unit that separates low interference light from the light source and reflected / scattered light returned from the subject, respectively A second optical path for guiding the low interference light separated by the light separating means, a third optical path for guiding the reflected / scattered light separated by the light separating means, Or provided in one of the third optical paths To vary the optical path length of the low interference light or reflected / scattered light,
A first optical path length varying means comprising an optical scanning means for changing the direction of the light beam and an optical element for changing the optical path length in accordance with the direction; A variable optical path length mechanism comprising a second optical path length changing means, a low interference light of the second optical path and a reflection / reflection of the third optical path.
Coupling means for coupling and interfering scattered light, detection means for detecting the interference by the coupling means as an interference signal, signal processing of the interference signal detected by the detection means to generate a tomographic image of the subject An optical imaging apparatus comprising: an image generating unit.

(Additional Item 2) In the additional item 1, the first
The optical scanning means of the optical path length varying means is an angle changing means for changing the angle of the light beam.

(Additional Item 3) The optical scanning means according to Additional Item 2, wherein the light beam is changed from a specific angle from the optical axis of the light beam.

(Additional Item 4) In Additional Item 2, the angle changing means includes any one of AOD, EOD, and holographic scanner.

(Additional Item 5) In the additional item 1, the first
The optical element of the optical path length varying means includes a Fresnel lens.

(Additional Item 6) In the additional item 1, the first
The optical element of the optical path length varying means is a combination of an optical lens and a step-shaped optical block having different optical distances.

(Appendix 7) In an optical imaging apparatus for irradiating a subject with light having low coherence and constructing a tomographic image of the subject from information on reflected / scattered light reflected / scattered from the subject, A light source that emits light of low coherence; a first optical path unit that guides light from the light source to the subject; and a light source that connects to the first optical path unit and guides the low interference light to the subject. An optical scanning probe that can be scanned and detached at least one-dimensionally, and a light separating unit that separates the low interference light from the light source and the reflected and scattered light returned from the subject, and the light A second optical path for guiding the low interference light separated by the separating means, a third optical path for guiding the reflected / scattered light separated by the light separating means, and the second or third light path. Said low interference provided on one side of the optical path Alternatively, in order to change the optical path length of the reflected / scattered light, the optical beam is converted into a slender shape, a part of the light is extracted, and the position is changed to change the optical path length according to the position. Element consisting of
A variable optical path length mechanism comprising: a variable optical path length means; a second optical path length changing means corresponding to an individual difference in the optical path length of the optical scanning probe; a low interference light of the second optical path and a third optical path; Coupling means for coupling the reflected and scattered light of the interference, detection means for detecting the interference by the coupling means as an interference signal,
An optical imaging apparatus, comprising: image processing means for processing the interference signal detected by the detection means to generate a tomographic image of the subject.

(Additional Item 8) In the additional item 7, the first
The optical path length varying means is a beam shape changing means for changing a light beam into an elongated shape and a rotatable disk having a plurality of holes in a disk.

(Supplementary note 9) In Supplementary note 8, the rotatable disk includes a plurality of slits.

(Supplementary note 10) In Supplementary note 8, the rotatable disk includes a plurality of pinholes.

(Appendix 11) In an optical imaging apparatus for irradiating a subject with light having low coherence and constructing a tomographic image of the subject from information on reflected / scattered light reflected / scattered from the subject, A light source for generating light of low coherence; first optical path means for guiding light from the light source to the subject; and connecting the first optical path means for guiding the low interference light to the subject. An optical scanning probe that emits light and is at least one-dimensionally scannable and detachable, a light separating unit that separates the low interference light from the light source and the reflected / scattered light returned from the subject, A second optical path for guiding the low interference light separated by the light separating means,
A third optical path for guiding the reflected / scattered light separated by the light separating means, and an optical path length of the low interference light or the reflected / scattered light provided on one of the second or third optical paths. An optical element that traverses the light beam to be variable,
An optical path length varying mechanism comprising first optical path length varying means for varying the optical path length in accordance with the position of the optical element, and second optical path length varying means for varying the individual optical path length of the optical scanning probe. And the low interference light of the second optical path and the reflection of the third optical path.
Coupling means for coupling and interfering scattered light, detection means for detecting the interference by the coupling means as an interference signal, signal processing of the interference signal detected by the detection means to generate a tomographic image of the subject An optical imaging device, comprising: an image generation unit.

(Additional Item 12) In the additional item 11, the optical element of the first optical path length varying means is a stepped optical block having different movable optical distances.

(Additional Item 13) In the additional item 12, a plurality of the optical blocks are attached to the rotatable disk.

(Additional Item 14) In Additional Items 1, 7, and 11, the second optical path length varying means is means for changing the distance in the optical axis direction with respect to a light beam parallel to the optical axis. .

[0095]

As described above, according to the present invention, the coupling means has the second optical path length adjusted by the optical path length adjusting mechanism.
The light having low coherence of the light path means and the reflected / scattered light of the third light path means are combined and caused to interfere with each other, the detection means detects the interference by the combining means as an interference signal, and the image generation means is detected by the detection means. Since the tomographic image of the subject is generated by signal processing of the interference signal, the OCT device capable of exchanging probes can produce an optical tomographic image that is continuous at a high speed with good S / N. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an optical imaging device according to a first embodiment of the present invention;

FIG. 2 is a configuration diagram showing a configuration of an optical scanning probe and a rotation driving device.

FIG. 3 is an explanatory view in which the optical scanning probe of FIG. 1 is used in combination with an endoscope;

FIG. 4 is a configuration diagram showing a configuration of an optical path length varying mechanism in FIG. 1;

FIG. 5 is a configuration diagram illustrating an optical scanning unit in FIG. 4;

FIG. 6 is an explanatory diagram for explaining the operation of the optical path length varying mechanism of FIG. 4;

FIG. 7 is an explanatory diagram for explaining the operation of the variable optical path length mechanism of FIG. 4;

FIG. 8 is a configuration diagram showing a first modification of the optical scanning unit of FIG.

FIG. 9 is a configuration diagram showing a second modification of the optical scanning unit of FIG.

FIG. 10 is a configuration diagram showing a first modification of the optical path length varying mechanism of FIG. 1;

FIG. 11 is a configuration diagram illustrating an optical block in FIG. 10;

FIG. 12 is a configuration diagram showing a configuration of an optical path length variable mechanism according to a second embodiment of the present invention.

FIG. 13 is a configuration diagram illustrating the rotating disk of FIG. 12;

FIG. 14 is a configuration diagram showing a modification of the rotating disk of FIG. 12;

FIG. 15 is a configuration diagram showing a configuration of an optical path length varying mechanism according to a third embodiment of the present invention.

FIG. 16 is an explanatory diagram illustrating the rotating disk of FIG. 15;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical imaging device 2 ... Low coherence light source 3, 5, 28, 29 ... Single mode fiber 4, 30 ... Optical coupler part 6 ... Optical scanning probe 7 ... Rotation drive device 22 ... Optical path length variable mechanism

Continuation of the front page (72) Inventor Tadafumi Hirata 2-43-2 Hatagaya, Shibuya-ku, Tokyo F-term in Olympus Optical Co., Ltd. (reference) 2G059 AA05 BB08 BB12 EE09 EE11 FF01 GG02 GG06 GG09 HH01 JJ11 JJ17 JJ30 KK01 LL01 LL02 MM01 PP04

Claims (3)

[Claims] 1. A light source that supplies the low coherence light for constructing a tomographic image of the test object by reflected / scattered light obtained by irradiating the test object with low coherence light; A first optical path means for guiding the low coherence light to the subject and guiding reflected / scattered light from the subject; and detachably connected to the first optical path means. A first optical scanning unit that guides the low-interference light to the subject and scans at least one-dimensionally; and the low-interference light source provided in the middle of the first optical scanning unit. Light separating means for separating a part of the light having a low intensity and light reflected and scattered from the subject from the first light scanning means; and guiding the light having low coherence separated by the light separating means. A second optical path means, and the reflected / scattered light separated by the light separating means. A third optical path unit that emits light, a first optical path length changing unit that changes an optical path length provided on one of the second and third optical path units, and an optical path length of the first optical scanning unit. An optical path length adjusting mechanism having second optical path length changing means for adjusting an optical path length; and the second optical path length adjusted by the optical path length adjusting mechanism.
Coupling means for coupling the low coherent light of the optical path means and reflected / scattered light of the third optical path means to cause interference; detection means for detecting interference by the coupling means as an interference signal; and detection means An image generating means for performing signal processing on the interference signal detected by the method to generate a tomographic image of the subject. 2. The first optical path length changing unit includes: a second optical scanning unit that changes a direction of low coherence light or reflected / scattered light separated by the light separating unit; and the second light. 2. An optical element having a different optical path length according to a direction selected by the scanning means.
The optical imaging device according to item 1. 3. The optical imaging apparatus according to claim 1, wherein the second optical path length changing means changes the distance in the optical axis direction for light parallel to the optical axis.