JP2004154257A - Scanning confocal probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanning confocal probe with excellent temperature characteristics, capable of reducing the diameter of the probe and simplifying the manufacture and assembly processes. <P>SOLUTION: This scanning confocal probe has a scanning mirror for scanning the luminous flux irradiated from a light source in a biological tissue inside a celom, and also has a mounting substrate for mounting the scanning mirror in an optical path of the luminous flux. The mounting substrate is made of an optical material transmitting the luminous flux irradiated from the light source. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a scanning confocal probe capable of observing a tomographic image of a living tissue in a body cavity at a high magnification.
[0002]
[Prior art]
Conventionally, when a living tissue is inspected by a precision diagnostic test, a part of the living tissue to be inspected is cut off using a treatment tool such as cutting forceps to examine the inside of the living tissue, and the outside of the body is inspected. And inspected it. Therefore, the diagnosis time becomes long, and the patient cannot be treated promptly.
[0003]
In recent years, confocal probes capable of observing a tomographic image of a living tissue have been widely used. This confocal probe is a probe equipped with a small micro-machined confocal device used in a confocal microscope. The confocal device includes a scanning mirror, and the scanning mirror scans a laser beam with an observation target to obtain a two-dimensional or three-dimensional observation image (for example, see Patent Documents 1 and 2). ).
[0004]
[Patent Document 1]
Japanese Patent No. 3032720 (Items 3 to 5, FIGS. 1 to 5)
[Patent Document 2]
Japanese Patent No. 3052150 (Items 3, 4 and 1)
[0005]
[Problems to be solved by the invention]
The scanning mirror used in the above-described confocal device is mounted on a semiconductor material such as a silicon substrate. The board on which the scanning mirror is mounted is mounted in the apparatus by a board mounting section provided on the inner wall of the housing. However, since the substrate mounting portion is provided outside the scanning mirror with respect to the optical axis, there are disadvantages in that the device becomes large and the probe diameter tends to be large. Further, since each scanning mirror having a different scanning direction is mounted on a separate silicon substrate, there is a problem that the manufacturing and assembling processes are complicated and the cost is increased.
[0006]
When the expansion coefficient of an optical material such as BK7 or synthetic quartz used for each optical system is compared with the expansion coefficient of the silicon substrate, the expansion coefficient of the silicon substrate is several tens times larger. For this reason, the larger the temperature change received by the confocal device, the greater the amount of deviation in the positional relationship between each optical system and the scanning mirror due to the difference in the expansion rate, and the laser beam that scans the observation target. Is likely to deviate from the optical axis. That is, since the temperature characteristics are poor, it is difficult to obtain an accurate observation image when observing under conditions where the temperature around the probe is high.
[0007]
SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a scanning confocal probe which can be reduced in diameter, can simplify the manufacturing and assembling steps, and has excellent temperature characteristics.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, a scanning confocal probe according to one embodiment of the present invention is a scanning confocal probe having a scanning mirror that scans a light beam emitted from a light source to a living tissue in a body cavity, A mounting board for mounting a scanning mirror is provided in the optical path of the light beam. The mounting substrate is made of an optical material that transmits a light beam emitted from a light source. That is, by mounting the scanning mirror on a substrate made of an optical material (for example, BK7, synthetic quartz), the difference in expansion coefficient between each optical element provided in the probe and the substrate on which the scanning mirror is mounted is reduced. I do. As a result, even when the temperature change received by the probe is large, it is possible to suppress the amount of deviation of the positional relationship between each optical element and the scanning mirror due to the difference in the expansion coefficient, so that the temperature characteristics are improved. Furthermore, by disposing the substrate on which the scanning mirror is mounted in the optical path of the light beam emitted from the light source, the space used as the optical path and the space for disposing the mounting substrate can be used, so that the external shape of the probe A certain housing can be made smaller, and the diameter of the probe can be reduced.
[0009]
In the scanning confocal probe, the scanning mirror includes a first scanning mirror that scans a light beam emitted from a light source in a predetermined direction and a second scanning mirror that scans a light beam in a direction orthogonal to the first scanning mirror. And two scanning mirrors. Each scanning mirror is mounted on the same optical element substrate. That is, since the number of substrates on which the scanning mirror is mounted can be reduced, the manufacturing and assembling steps can be simplified.
[0010]
Further, the scanning confocal probe has an objective optical system for condensing a light beam emitted from a light source on a living tissue, and the objective optical system and the mounting substrate are made of the same material. That is, since there is no difference in the expansion coefficient between each optical element provided in the probe and the substrate on which the scanning mirror is mounted, the temperature characteristics are improved.
[0011]
Further, the scanning confocal probe has a pinhole arranged to remove reflected light other than reflected light from the object-side focal plane of the objective optical system, out of reflected light reflected by the living tissue. The pinhole is an end face of the single mode optical fiber on which a light beam from the object-side focal position of the objective optical system enters. That is, by arranging the end face of a single mode optical fiber having a small core diameter at a position conjugate with the object-side focal position of the objective optical system, this optical fiber has the same function as a pinhole used in a confocal optical system. It is possible to have a function of transmitting an observation image obtained by the focusing optical system to an external device such as a processor.
[0012]
In addition, a confocal endoscope apparatus including the scanning confocal probe according to any one of the above, based on a light source that irradiates a living tissue, and a reflected light of a subject guided from the scanning confocal probe. And an image signal generation unit for generating an image signal.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram showing a configuration of a scanning confocal probe device 500 according to the first embodiment of the present invention. The scanning confocal probe device 500 includes the scanning confocal probe 100, a processor 300, and a monitor 400.
[0014]
An operator can insert the scanning confocal probe 100 into a forceps channel of an endoscope (not shown) or the like, and obtain an observation image of a body cavity through the probe. The observation image obtained by the probe is subjected to image processing by the processor 300 and displayed on the monitor 400.
[0015]
The processor 300 includes a laser light source 310, a coupler 320, a light receiving element 330, a CPU 340, an image processing circuit 350, and an operation panel 360.
[0016]
The laser light source 310 oscillates a He-Ne laser having an oscillation wavelength of 632 nm. The shorter the wavelength of the laser light source used for the confocal optical system, the higher the resolution can be obtained. That is, the laser light source 310 is not limited to the He-Ne laser, but may be, for example, a short wavelength Ar ⁺ laser.
[0017]
The light beam oscillated from the laser light source 310 is guided to the scanning confocal probe 100 via a coupler 320 as an optical splitter.
[0018]
The scanning confocal probe 100 includes an optical fiber 110, a GRIN lens 120, a glass substrate 130, micro mirrors 140 and 150, and an objective lens 170.
[0019]
The optical fiber 110 is a single mode fiber that transmits a single mode. The optical fiber 110 transmits the light beam output from the processor 300 toward the GRIN lens 120.
[0020]
The GRIN lens 120 is a lens molded from an optical material whose refractive index has a gradient inside the medium. The light beam emitted from the optical fiber 110 is incident on the GRIN lens 120, becomes a parallel light beam, and is emitted toward the glass substrate 130.
[0021]
The glass substrate 130 is a substrate for mounting a micromirror, and has a mounting surface 130a on which the micromirror 140 is mounted and a mounting surface 130b on which the micromirror 150 is mounted. The glass substrate 130 is formed of a glass material such as BK7 or synthetic quartz used for an optical element, and the mounting surface thereof is set at 45 degrees with respect to the optical axis in the optical path of the parallel light beam emitted from the GRIN lens 120. It is arranged to tilt. Note that the angle formed between the micromirror mounting surface and the optical axis is not limited to 45 degrees, and may be changed as appropriate depending on various conditions such as the refractive index of the glass substrate 130 and the space in the probe.
[0022]
The parallel light beam emitted from the GRIN lens 120 enters the mounting surface 130b of the glass substrate 130, is refracted, and is guided to the micro mirror 140 mounted on the mounting surface 130a.
[0023]
FIG. 2 is a diagram showing the configuration of the micro mirrors 140 and 150. Each of the micro mirrors 140 and 150 has a plate 161, a torsion bar 162, and a pointing frame 163 integrally formed by etching from a silicon plate. Further, the plate 161 has a mirror 164 formed by depositing a reflective film (for example, aluminum, gold, a dielectric multilayer film, or the like) at the center thereof. Further, on the plate 161, the torsion bar 162, and the indication frame 163, a planar coil 165 made of a copper thin film is provided. Further, a yoke portion 166 composed of a permanent magnet and a yoke is provided in parallel with the longitudinal direction of the torsion bar 162.
[0024]
The yoke part 166 generates a magnetic field in a direction (X ′ direction in FIG. 2) substantially parallel to the plate 161 and substantially perpendicular to the longitudinal direction of the torsion bar 162. When a driving current is supplied from a power supply (not shown) to the planar coil 165, driving forces having different directions in the Z ′ direction, that is, torques are generated on two sides of the plate 161 parallel to the torsion bar 162 according to Fleming's left hand rule. I do. The torque generated at this time increases in proportion to the increase in the drive current supplied to the planar coil 165.
[0025]
The plate 161 swings in the direction of the arrow A in the figure according to the generated torque. At this time, since the plate 161 and the torsion bar 162 are integrally formed, the torsion bar 162 is twisted to generate a spring reaction force. As a result, the plate 161 rotates to an angle at which the torque and the spring reaction force are balanced. Then, when the plate 161 reaches an angle at which the forces are balanced, the plate 161 stops at that angle.
[0026]
The micromirror 140 and the micromirror 150 are disposed such that their torsion bars are orthogonal to each other. When the plate of the micromirror 140 rotates, the laser light scans the observed portion 10 in the X direction, and when the plate of the micromirror 150 rotates, the laser light scans the observed portion 10 in the Y direction. Is done. Here, the X and Y directions are directions orthogonal to the optical axis, and indicate a plane direction with respect to the observed portion 10.
[0027]
The micromirrors 140 and 150 have two detection coils (not shown) on the opposite side of the surface of the plate 161 on which the planar coil 165 is provided. The detection current for detecting the displacement angle of the plate 161 is superimposed on the drive current flowing through the plane coil 165 and flows. Based on this detection current, an induced voltage due to mutual inductance between the planar coil 165 and each detection coil is generated in each detection coil.
[0028]
The two detection coils are disposed equidistant from the planar coil 165, respectively. That is, when the plate 161 is in a horizontal state (a state in which no torque is generated), the difference between the induced voltages is zero. However, when the plate 161 swings, one of the detection coils approaches the plane coil 165 and the other detection coil separates from the plane coil 165, so that a difference occurs between the induced voltages generated in the detection coils. That is, by detecting the change in the induced voltage, the displacement angle of the micromirror can be detected.
[0029]
The parallel light flux guided to the micromirror 140 exits the mounting surface 130a, is reflected by the micromirror 140, reenters the mounting surface 130a, and is guided to the micromirror 150. Then, the parallel light beam reflected by the micro mirror 150 exits the mounting surface 130a and is guided to the objective lens 170.
[0030]
The objective lens 170 is formed of the same optical material as the glass substrate 130, for example, a glass material such as BK7 or synthetic quartz. The parallel luminous flux emitted from the mounting surface 130a is focused on the surface portion or tomographic portion of the observed portion 10 via the objective lens 170.
[0031]
The light beam emitted to the observation site 10 is reflected by the observation site 10 and enters the objective lens 170. The light is converted into a parallel light beam by the objective lens 170, and enters the GRIN lens 120 via the same optical path as described above.
[0032]
Since the optical fiber 110 is a single mode fiber as described above, its core diameter is about 3 to 9 μm (depending on the wavelength used) and is very small. The end face 110 a of the optical fiber 110 is disposed at a position conjugate with the object-side focal position of the objective lens 170. In other words, of the light beams incident on the GRIN lens 120, the reflected light of the light beam focused on the observed portion 10 is focused on the end face 110a. The light beam focused on the end face 110a enters the optical fiber 110, and is received by the light receiving element 330 via the coupler 320.
[0033]
However, the reflected light of the observation site 10 other than the reflected light from the object-side focal plane of the objective lens 170 is not focused on the end face 110 a and does not enter the optical fiber 110, and thus is not transmitted to the processor 300. That is, the optical fiber 110 transmits only the reflected light of the observation site 10 on the focal plane of the objective lens 170 to the processor 300. That is, in this embodiment, the end face 110 a of the optical fiber 110 is obtained by the function of a pinhole that blocks light other than the reflected light from the object-side focal plane of the objective lens 170 and the optical system of the scanning confocal probe 100. And a function of transmitting the observed image to the processor 300.
[0034]
Further, since a pinhole, that is, an aperture stop is provided on the focal plane of the GRIN lens 120, the optical system in the probe is a telecentric optical system, and the loss of light amount is extremely small.
[0035]
The light beam received by the light receiving element 330 is photoelectrically converted into an image signal, which is output to the image processing circuit 350. The image processing circuit 350 performs predetermined image processing on the image signal and converts the image signal into various video signals such as a composite video signal, an RGB signal, and an S video signal. Then, when these video signals are output to the monitor 400, an observation image of the observation site 10 on the focal plane of the objective lens 170 generated by the scanning confocal probe 100 is displayed on the monitor.
[0036]
An operator can selectively observe an image obtained by the scanning confocal probe 100 by operating the operation panel 360 provided in the processor 300.
[0037]
Information input to the operation panel 360 by the operator is transmitted to the CPU 350. CPU 350 drives micromirror 140 and micromirror 150 based on the transmitted information. When the micromirror 140 or the micromirror 150 is driven, as described above, the laser beam scans the observed portion 10 in the X direction or the Y direction (that is, the plane direction). Then, the reflected light of the scanned portion is transmitted to the processor 300 as an observation image.
[0038]
Further, by changing the scanning angle of the micromirror (that is, the range of the laser beam scanned at the observed portion 10), the visual field of the observed image can be easily changed. When the scanning angle is small, the observation image is a small area, and when the scanning angle is large, the observation image is a large area.
[0039]
FIG. 3 is a block diagram showing a configuration of a scanning confocal probe device 500y according to the second embodiment of the present invention. In the scanning confocal probe device 500y, the same components as those of the scanning confocal probe device 500 of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. I do. The scanning confocal probe device 500y includes a scanning confocal probe 100y, a processor 300, and a monitor 400.
[0040]
In this embodiment, a two-dimensional image of a living tissue is obtained using one micromirror. That is, the micromirror 150 of the first embodiment is configured by replacing it with a biaxial scanning micromirror 150y (that is, one that operates simultaneously in the X direction and the Y direction) 150y. At this time, the micromirror 140 according to the first embodiment is replaced with a mirror (for example, a metal single-layer film or a dielectric multilayer film) 140y.
[0041]
The light beam emitted from the laser light source 310 enters the glass substrate 130 via the optical fiber 110 and the GRIN lens 120. A mirror 140 is bonded to a mounting surface 130a of the glass substrate 130, and a micro mirror 150y is mounted on the mounting surface 130b. The light beam incident on the glass substrate 130 is reflected by the mirror 140y and guided to the micro mirror 150y. Then, this light beam is scanned in the X direction and the Y direction with respect to the observed portion 10 by the micro mirror 150y. The reflected light from the observation site 10 is subjected to image processing by the processor 300 as in the first embodiment, and a two-dimensional image of the observation site 10 is displayed on the monitor 400. In the second embodiment, the mirror is bonded to the mounting surface 130a and the micro mirror is mounted on the mounting surface 130b. However, the micro mirror is mounted on the mounting surface 130a, and the mirror is mounted on the mounting surface 130b. May be adhered.
[0042]
FIG. 4 is a block diagram showing the configuration of a scanning confocal probe device 500z according to the third embodiment of the present invention. In the scanning confocal probe device 500z, the same components as those of the scanning confocal probe device 500 of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. I do. The scanning confocal probe device 500z includes a scanning confocal probe 100z, a processor 300z, and a monitor 400.
[0043]
The processor 300z has a laser light source 310z having a Brewster window, and a polarization splitting film (not shown) is disposed near the laser light source 310z. The Brewster window and the polarization separation film are arranged such that the light beam oscillated from the laser light source 310z becomes an s-polarized light beam with respect to the polarization separation film. Therefore, the light beam emitted from the laser light source 310z is converted into a light beam having s-polarized light.
[0044]
The light beam emitted from the laser light source 310z enters the optical fiber 110 in the scanning confocal probe 100z via the coupler 320. The light beam emitted from the optical fiber 110 is converted into a parallel light beam by the GRIN lens 120 and guided to the polarization beam splitter cube 180.
[0045]
The polarizing beam splitter cube 180 has a polarizing film 181, and the polarizing film 181 is disposed so as to form an angle of 45 degrees with the optical axis. The polarizing film 181 has a property of reflecting s-polarized light of linearly polarized light and transmitting p-polarized light.
[0046]
Further, a λ / 4 wavelength plate 190 and a λ / 4 wavelength plate 191 are attached to each surface of the polarization beam splitter cube 180 located in a direction parallel to the optical axis direction. The λ / 4 wavelength plates 190 and 191 convert the linearly polarized light beam into a circularly polarized light beam, and convert the circularly polarized light beam into a linearly polarized light beam.
[0047]
The parallel light beam of the s-polarized light guided to the polarization beam splitter cube 180 is bent by 90 degrees by the polarizing film 181 and guided to the λ / 4 wavelength plate 190. The parallel light beam passes through the λ / 4 wavelength plate 190, is converted into a circularly polarized parallel light beam by the λ / 4 wavelength plate 190, and is guided to the micro mirror 140.
[0048]
The parallel light beam of the circularly polarized light guided to the micromirror 140 is reflected by the mirror of the micromirror 140, passes through the λ / 4 wavelength plate 190 again, and becomes a parallel light beam in a p-polarized state. Since the polarizing film 181 has the property of transmitting p-polarized light as described above, this parallel light beam of p-polarized light passes through the polarizing film 181 and is guided to the λ / 4 wavelength plate 191.
[0049]
The p-polarized parallel light beam guided to the λ / 4 wavelength plate 191 passes through the λ / 4 wavelength plate 191, is converted into a circularly polarized light parallel light beam by the λ / 4 wavelength plate 191, and is guided to the micromirror 150. . Then, this circularly polarized parallel light beam is reflected by the mirror of the micromirror 150, passes through the λ / 4 wavelength plate 191 again, and becomes an s-polarized parallel light beam.
[0050]
The parallel light flux of the s-polarized light is bent by 90 degrees by the polarizing film 181 and guided to the objective lens 170. Then, the parallel light flux is focused on the surface portion or the tomographic portion of the observed portion 10 via the objective lens 170.
[0051]
Then, similarly to the first embodiment, the light beam emitted to the observation site 10 is reflected at the observation site 10 and enters the objective lens 170. Then, the light beam is converted into a parallel light beam by the objective lens 170, enters the GRIN lens 120 via the same optical path as described above, and at the end face 110a of the optical fiber 110, only the reflected light of the focal plane of the objective lens 170 is transmitted to the processor 300z. Then, predetermined image processing is performed in the processor 300z, and an image of only the focused part of the observed part 10 without blur or flare is displayed on the monitor 400.
[0052]
In the first embodiment, the configuration of the present invention can be realized with a small number of components without using a λ / 4 wavelength plate, so that the cost of the confocal probe can be reduced.
[0053]
In addition, even if the mounting substrate (the polarization beam splitter cube 180) is displaced in the third embodiment, the optical axis of the GRIN lens 120 and the objective lens 170 does not deviate, so that the reliability of the device is improved. I do.
[0054]
The above is the embodiment of the present invention. The present invention is not limited to these embodiments, and can be modified in various ranges.
[0055]
In this embodiment, the observation image of the observed portion 10 obtained by the confocal optical system is a two-dimensional image obtained by using a micromirror that scans the laser light in the XY directions. A micro mirror that scans in the depth direction of the site 10 may be added to obtain a three-dimensional image.
[0056]
Further, in this embodiment, a He-Ne laser is used as a light source for irradiating the observation site 10, but an ultra-high pressure mercury lamp that irradiates short-wavelength light including near ultraviolet light may be used as the light source. . In this case, it is possible to observe the fluorescence emitted from the observation site 10.
[0057]
【The invention's effect】
As described above, the scanning confocal probe and the scanning confocal probe device of the present invention have an optical element substrate on which a micromirror made of an optical material that transmits a light beam is mounted. For this reason, the difference in expansion coefficient between each optical element provided in the probe and the substrate on which the micromirror is mounted is reduced. As a result, even when the temperature change received by the probe is large, it is possible to suppress the amount of displacement of the positional relationship between each optical element and the micromirror due to the difference in expansion coefficient, and thus the temperature characteristics are improved.
[0058]
The optical element substrate is disposed in the optical path of the light beam emitted from the light source. Therefore, a space used as an optical path and a space for disposing the mounting substrate can be used, and space can be saved. As a result, the outer casing of the probe can be reduced in size, and the diameter of the probe can be easily reduced.
[0059]
Further, since a plurality of micromirrors can be mounted on a common substrate, it is possible to reduce the number of parts, the number of assembling steps, and the assembling time, leading to cost reduction.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a scanning confocal probe device according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of a micromirror used in an embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a scanning confocal probe device according to a second embodiment of the present invention.
FIG. 4 is a block diagram illustrating a configuration of a scanning confocal probe device according to a third embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 100 scanning confocal probe 300 processor 500 scanning confocal probe device

Claims (5)

A scanning confocal probe having a scanning mirror that scans a light beam emitted from a light source to a living tissue in a body cavity,
The scanning confocal probe has a mounting board for mounting the scanning mirror in an optical path of the light beam,
The scanning confocal probe, wherein the mounting substrate is made of an optical material that transmits the light beam. A first scanning mirror that scans the light beam in a predetermined direction;
A second scanning mirror that scans the light beam in a direction orthogonal to the first scanning mirror.
The scanning confocal probe according to claim 1, wherein the first scanning mirror and the second scanning mirror are mounted on the same mounting substrate. The scanning confocal probe has an objective optical system that focuses the light beam on the living tissue,
The scanning confocal probe according to claim 1, wherein the objective optical system and the mounting substrate are made of the same material. The scanning confocal probe has a pinhole disposed to remove reflected light other than the reflected light from the object-side focal plane of the objective optical system, of the reflected light reflected by the living tissue,
The scanning confocal probe according to claim 3, wherein the pinhole is an end face of a single mode optical fiber on which a light beam from an object-side focal position of the objective optical system is incident. A scanning confocal probe according to any one of claims 1 to 4,
A light source for irradiating living tissue,
An image signal generation unit that generates an image signal based on reflected light of the living tissue guided from the scanning confocal probe.

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