JP2004258142A - Scanning confocal probe - Google Patents

Abstract

An object of the present invention is to provide a side-view scanning confocal probe that can simplify an assembling process including a positioning operation of a scanning mirror, and is reduced in size and diameter.
A scanning confocal probe includes a light beam incident end surface and a light beam exit end surface that are orthogonal to each other, a polarization separation surface having an angle of approximately 45 ° with either the light beam incidence end surface or the light beam exit end surface, and a polarization separation surface. A predetermined surface that forms an angle of approximately 45 ° and receives a light beam through the polarization separation surface, and is disposed such that the polarization separation surface is inclined at approximately 45 ° with respect to the direction of incidence of the light beam from the light source. A rectangular parallelepiped polarizing beam splitter; a polarizing unit disposed on a predetermined surface for changing the polarization state of the light beam; and a scanning unit mounted on the polarizing unit and scanning the light beam transmitted through the polarizing unit on the living tissue. The light beam from the light source is incident on the scanning means via the light beam incident end face, the deflection separation surface, and the polarizing means, is deflected by the scanning means, and is emitted from the light beam emitting end face. .
[Selection diagram] Fig. 1

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, and more particularly to a side-view scanning confocal probe for observing a living tissue from a side surface of the probe.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when a living tissue is inspected by a precision diagnostic test, a part of the living tissue to be inspected is collected using a treatment tool such as a cutting forceps, and then the inspection is performed outside the body. Therefore, the diagnosis time is lengthened, and the treatment cannot be quickly performed on the subject.
[0003]
2. Description of the Related Art In recent years, confocal probe devices that can observe a tomographic image of a living tissue have been widely used. The confocal probe device has a micro-machined miniature confocal probe used at the confocal microscope at the tip. The confocal probe device obtains a two-dimensional or three-dimensional observation image by causing a scanning mirror provided inside the probe to scan the observation target with laser light. Such an apparatus is disclosed, for example, in Patent Document 1 or Patent Document 2 below.
[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]
In the probe of the above-mentioned conventional confocal probe device, the scanning mirror is mounted in a cavity formed by cutting a semiconductor material such as a silicon substrate into a predetermined shape. The substrate on which the scanning mirror is mounted is mounted on the inner wall of the probe by a substrate mounting portion or the like. Therefore, the number of steps in the probe assembling operation increases, and each step becomes complicated. In particular, the scanning mirror is required to be positioned with high precision in relation to the optical system in another probe, but it is extremely difficult to mount the scanning mirror while positioning it with high precision in the cavity. Further, the substrate mounting portion is provided outside the scanning mirror with respect to the optical axis (on the inner wall side of the probe) with respect to the optical axis. For this reason, there is a disadvantage that the whole probe becomes large or the diameter becomes large.
[0006]
[Problems to be solved by the invention]
In view of the above circumstances, the present invention provides a side-view type scanning confocal probe that can simplify the assembly process including the positioning operation of the scanning mirror, and is reduced in size and diameter. The purpose is to:
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a scanning confocal probe according to the present invention is directed to a side view for observing a living tissue in a body cavity by irradiating a light beam from a light source in a direction substantially perpendicular to a direction of insertion into the body cavity. A scanning confocal probe of a type, in which a light beam incident end face and a light beam exit end face that are orthogonal to each other, a polarization separation surface having an angle of approximately 45 ° with either the light beam incidence end face or the light beam exit end face, A predetermined surface that forms an angle of approximately 45 ° and receives a light beam through the polarization separation surface, and is disposed such that the polarization separation surface is inclined at approximately 45 ° with respect to the direction of incidence of the light beam from the light source. A rectangular parallelepiped polarizing beam splitter, a polarizing unit disposed on a predetermined surface and changing a polarization state of a light beam, and a scanning unit mounted on the polarizing unit and scanning the light beam transmitted through the polarizing unit on the living tissue. And the luminous flux from the light source is Light-incident side, the deflection separation surface, incident on the scanning means through the polarizing means, after being deflected by said scanning means, characterized in that it is emitted from the light emission end surface.
[0008]
By arranging a polarizing beam splitter for guiding the light beam for the side view in the light path of the light beam from the light source, the space used as the light path and the space for arranging the scanning means can be shared. Therefore, the size of the outer casing of the probe can be reduced, and the probe can be reduced in size and diameter.
[0009]
In addition, the scanning confocal probe further includes a light condensing unit that condenses the light flux emitted from the polarization beam splitter on a living tissue in the body cavity. It is preferable that the light converging means be provided with a diffractive surface on the light beam exit end face of the polarizing beam splitter, thereby saving space.
[0010]
Further, it is desirable that the scanning means is disposed at a position where the light is focused when a parallel light beam is incident on the light-collecting means from the living tissue side. As a result, the scanning unit and the condensing unit have a telecentric relationship, and the light beam enters the living tissue, which is the observation site, at right angles. Therefore, a brighter and more detailed image can be observed while suppressing the light amount loss.
[0011]
According to the scanning confocal probe of the fifth aspect, it is desirable that the scanning means has a two-axis scanning mirror that scans the light beam in the first direction and the second direction orthogonal to the first direction. .
[0012]
When the light from the light source is s-polarized light, a plane parallel to the light-emitting end face may be set as the predetermined plane. When the light from the light source is p-polarized light, the plane perpendicular to the light-emitting end face may be the predetermined plane. By mounting the scanning means on any surface of the polarizing beam splitter, relative positioning between the scanning means and the polarizing beam splitter can be easily and accurately performed. Thus, the manufacturing and assembling steps of the probe can be simplified.
[0013]
According to the eighth aspect of the present invention, the polarization beam splitter can be formed in a substantially regular hexahedron shape. Further, the polarizing means is a λ / 4 wavelength plate.
[0014]
The scanning confocal probe according to claim 10 is provided so as to remove reflected light other than reflected light from the object-side focal plane of the light condensing means, out of the reflected light reflected by the living tissue. Has a pinhole. The pinhole is the end face of the single mode optical fiber on which the light beam from the object-side focal position of the light collecting means is incident. That is, by arranging the end face of the single mode optical fiber having a small core diameter at a position conjugate with the object side focal position of the light condensing means, the optical fiber has a function of a pinhole used in a confocal optical system, It is possible to have a function of transmitting an observation image obtained by the confocal optical system to an external device such as a processor.
[0015]
Further, a confocal endoscope apparatus including the scanning confocal probe according to any one of the above, based on a light source for irradiating the living tissue, and reflected light of the living tissue transmitted from the scanning confocal probe And an image signal generation unit that generates an image signal.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram showing a schematic configuration of a scanning confocal probe device 500 according to an embodiment of the present invention. The scanning confocal probe device 500 includes the scanning confocal probe 100, a processor 300, and a monitor 400.
[0017]
The 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.
[0018]
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.
[0019]
The laser light source 310 has a light source unit and a Brewster window. The Brewster window is arranged so that a light beam oscillated from the light source unit becomes an s-polarized light beam with respect to a polarization separation film of the polarization beam splitter 130 described later.
[0020]
The laser light source 310 oscillates a He-Ne laser having an oscillation wavelength of 632 nm. Here, 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.
[0021]
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.
[0022]
The probe 100 includes a polarization maintaining fiber 110, a GRIN lens (or a collimating lens) 120, a polarization beam splitter 130, a micro mirror 140, a λ / 4 wavelength plate 150, and a cable 160. The polarization preserving fiber 110, the GRIN lens 120, and the polarization beam splitter 130 are installed and fixed along the inner wall of the probe 100 molded in a predetermined shape in advance. Therefore, relative positioning between the members can be performed very easily and with high accuracy. Note that the probe 100 is of a side-view type that irradiates a light beam from the light source 310 in a direction substantially orthogonal to the direction of insertion into the body cavity, that is, observes the observation site from the side of the probe.
[0023]
Probe 100 is electrically and optically connected to processor 300 by cable 160. The polarization maintaining fiber 110 is a single mode fiber that transmits a single mode. The polarization maintaining fiber 110 is disposed so as to pass through the inside of the cable 160 from the end of the cable 160 on the processor 300 side and enter the inside of the probe 100. That is, the polarization maintaining fiber 110 transmits the light beam output from the processor 300 toward the GRIN lens 120. In the cable 160, the polarization maintaining fiber 110 is covered by a jacket 160a.
[0024]
The GRIN lens 120 is a lens formed from an optical material having a refractive index having a gradient inside the medium, and functions as a collimator lens. That is, the light beam emitted from the polarization maintaining fiber 110 enters the GRIN lens 120, becomes a parallel light beam, and is emitted toward the polarization beam splitter 130. The parallel luminous flux emitted from the GRIN lens 120 enters the polarizing beam splitter 130 via the surface 130a at an incident angle of 0 °. In this specification, of the surfaces of the polarization beam splitter 130, the surface 130a on which the light beam from the light source 310 is incident is referred to as a light beam incident end surface for convenience.
[0025]
The polarizing beam splitter 130 is provided as a light guiding unit that bends the optical path of the incident light beam at a right angle. The polarization beam splitter 130 has a substantially regular hexahedron shape in which two inclined prisms each having a right-angled isosceles triangle on the bottom surface are bonded to each other. The bonding surface 130b of the polarization beam splitter 130 is provided with a polarizing film and functions as a polarization separation surface. The polarization beam splitter 130 is disposed such that the polarization splitting surface 130b forms an angle of 45 degrees with the optical path of the light beam incident via the light beam incident end surface 130a. The polarization beam splitter 130 is formed of a glass material such as BK7 or synthetic quartz.
[0026]
The polarization separation surface 130b has a characteristic of reflecting s-polarized light of linearly polarized light and transmitting p-polarized light. Therefore, the light beam (s-polarized light) incident through the light beam incident end surface 130a is reflected by the polarization separation surface 130b and guided to the surface 130c. The reflection angle at this time is 45 °.
[0027]
The surface 130c is orthogonal to the light-incident end surface 130a and intersects the polarization splitting surface 130b at 45 °. On the surface 130c, the λ / 4 wavelength plate 150 is provided. The λ / 4 wavelength plate 150 converts the linearly polarized light beam into a circularly polarized light beam, and converts the circularly polarized light beam into a linearly polarized light beam.
[0028]
A micro mirror 140 is mounted on the λ / 4 wavelength plate 150. The micro mirror 140 includes a mirror unit (not shown) and a support base (not shown) for rotatably holding the mirror unit. The micro mirror 140 is mounted on the polarization beam splitter 130 by joining the support base to the λ / 4 wavelength plate 150. The micromirror 140 scans the incident light beam in the X direction and the Y direction orthogonal to the X direction at the same time as the mirror section rotates under the control of the CPU 340. That is, the micro mirror 140 used in the present embodiment is of a two-axis scanning type. Note that the X direction and the Y direction are directions orthogonal to the optical axis of the objective lens 150 described later. The plane defined by the X direction and the Y direction substantially matches the surface of the observation site 10.
[0029]
As described above, the polarizing beam splitter 130 functions not only to bend the optical path of the incident light beam but also as a mounting unit for mounting the λ / 4 wavelength plate 150 and the micro mirror 140. As described above, the polarization beam splitter 130 is installed and fixed on the inner wall of the probe 100, so that relative positioning with other optical members is performed with high accuracy. Accordingly, the λ / 4 wavelength plate 150 and the micromirror 140 are positioned on the surface 130c of the polarizing beam splitter 140 at the same time as the positioning. Therefore, the burden on manufacturing the probe 100 can be reduced.
[0030]
The s-polarized light beam incident on the surface 130 c is converted into a circularly-polarized light beam by the λ / 4 wavelength plate 190 and guided to the micromirror 140. The parallel light beam of the circularly polarized light guided to the micromirror 140 is deflected by the micromirror 140 and again passes through the λ / 4 wavelength plate 190 to become a parallel light beam in a p-polarized state. Since the polarization splitting surface 130b has the property of transmitting p-polarized light as described above, the parallel light beam of p-polarized light transmitted through the λ / 4 wavelength plate 190 is transmitted through the polarization splitting surface 130b and guided to the surface 130d. In the present specification, of the surfaces of the polarization beam splitter 130, the surface 130d from which the parallel light beam is emitted via the micromirror 140 is referred to as a light beam emission end surface for convenience.
[0031]
A diffraction surface D is provided on the light beam exit end surface 130d. The parallel luminous flux incident on the surface 130d is condensed by the diffraction surface D, and focuses on the surface portion or tomographic portion of the observed portion 10. The transparent plane parallel plate 170 is provided to protect the light emitting end face 130c and the diffraction surface D provided on the end face 130c.
[0032]
In the present embodiment, the micromirror 140 is disposed at a position having a telecentric relationship with the diffraction surface D so that light is incident on the observation site 10 which is the focal plane at a substantially right angle. Specifically, a focal position micromirror 140 when a parallel light beam is incident on the diffraction surface D from the observation site 10 side is provided. Thereby, the light flux does not obliquely enter the observation site 10, and the light amount loss is reduced.
[0033]
The light beam condensed at the observation site 10 is reflected at the observation site 10 and enters the objective lens 150. Then, the light is converted into a parallel light beam by the objective lens 150, and enters the GRIN lens 120 via the same optical path as described above.
[0034]
The polarization maintaining fiber 110 is a single mode fiber as described above. Therefore, the core diameter is very small, about 3 to 9 μm, though it varies depending on the wavelength used. The end face 110a of the polarization maintaining fiber 110 is disposed at a position conjugate with the object-side focal position of the objective lens 150. In other words, of the light beams incident on the GRIN lens 120, only 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 polarization maintaining fiber 110 and is received by the light receiving element 330 via the coupler 320.
[0035]
In addition, the reflected light of the observation site 10 other than the reflected light from the object-side focal plane on the diffraction plane D is not focused on the end face 110 a and does not enter the polarization maintaining fiber 110, and is not transmitted to the processor 300. That is, in this embodiment, the end face 110 a of the polarization preserving fiber 110 is formed by the function of a pinhole for blocking light other than the reflected light from the object-side focal plane of the objective lens 150 and the optical system of the scanning confocal probe 100. It also has a function of transmitting the obtained observation image to the processor 300.
[0036]
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 150 generated by the scanning confocal probe 100 is displayed on the monitor.
[0037]
The surgeon operates the operation panel 360 included in the processor 300 to make settings related to images, such as the scanning direction and the scanning angle of the micro mirror 140. For example, by changing the scanning angle of the micromirror 140 (that is, the range of the laser beam scanned at the observation site 10), the field of view of the observation 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.
[0038]
Information input to the operation panel 360 by the operator is transmitted to the CPU 350. The CPU 350 controls the driving of the micro mirror 140 based on the transmitted information. When the micromirror 140 is driven, the laser beam scans the observed portion 10 in the X direction or the Y direction as described above. Then, the reflected light of the scanned portion is transmitted to the processor 300 as an observation image. Thereby, the surgeon can selectively observe the image obtained by the scanning confocal probe 100.
[0039]
According to the configuration of the above embodiment, even when the polarization beam splitter 130 is displaced, the optical axis of the GRIN lens 120 and the diffraction surface D do not deviate, so that the reliability of the device is improved.
[0040]
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.
[0041]
For example, in the above embodiment, the light beam from the light source 310 is s-polarized light with respect to the polarization splitting surface of the polarization beam splitter 130, but p-polarized light may be used. In this case, in the polarization beam splitter 130, the λ / 4 wavelength plate 150 and the micro mirror 140 may be provided not on the surface 130c but on the surface 130e facing the light beam incident end surface 130a.
[0042]
Further, the configuration of the polarizing beam splitter 130 is not limited to the above-described configuration (substantially regular hexahedral shape), and the angle between the light-incident end face and the light-exit end face is orthogonal to the light-incident end face or the light-exit end face is 45 °. The shape may be a rectangular parallelepiped provided with a polarization splitting surface such that
[0043]
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.
[0044]
Further, in the above-described embodiment, the diffraction surface D as the light condensing means is integrally formed on the light beam exit end face 130d of the polarization beam splitter 130. However, the same effect as in the above-described embodiment can be obtained by using another light condensing means. Obtainable. For example, an objective lens may be provided on the optical path of the light beam emitted from the light beam exit end face of the polarizing beam splitter 130. At this time, it is preferable to use the objective lens made of the same material as the polarization beam splitter 130. Thereby, the difference between the expansion coefficients of the optical elements is reduced. As a result, even when the temperature change applied to the probe is large, the amount of deviation in the positional relationship between the optical elements due to the difference in expansion coefficient can be suppressed, and the temperature characteristics are improved.
[0045]
【The invention's effect】
As described above, in the scanning confocal probe and the scanning confocal probe device of the present invention, the polarization beam splitter, which is the light guide means and on which the scanning means is mounted, is disposed in the space used as the optical path. Therefore, the space used as the optical path and the mounting space for the scanning means can be shared, and the space can be saved. Thus, the outer shape of the housing of the probe can be reduced, and the diameter of the probe can be easily reduced.
[0046]
Further, by mounting the scanning means on the surface of the polarizing beam splitter, positioning between the optical members can be performed easily and with high accuracy. Accordingly, it is possible to reduce the number of probe assembling steps and the assembling time, which leads to cost reduction.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a scanning confocal probe device according to an embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 100 scanning confocal probe 130 polarizing beam splitter 300 processor 500 scanning confocal probe device

Claims (11)

A side-view type scanning confocal probe for observing a living tissue in the body cavity by irradiating a light beam from a light source in a direction substantially perpendicular to an insertion direction into the body cavity,
A light beam incident end surface and a light beam exit end surface that are orthogonal to each other, a polarization separation surface having an angle of approximately 45 ° with either the light beam incident end surface or the light beam exit end surface, and an angle of approximately 45 ° with the polarization separation surface; A predetermined surface on which the light beam enters through the polarization splitting surface; and a rectangular parallelepiped polarized light disposed so that the polarization splitting surface is inclined at approximately 45 ° with respect to the incident direction of the light beam from the light source. A beam splitter,
Polarizing means disposed on the predetermined surface, for changing the polarization state of the incident light beam,
Scanning means attached to the polarizing means, and scans the light flux after passing through the polarizing means on the living tissue,
The light beam from the light source is incident on the scanning unit via the light beam incident end face, the deflection separation surface, and the polarizing unit, and after being deflected by the scanning unit, is emitted from the light beam exit end surface. Features a scanning confocal probe. The scanning confocal probe according to claim 1,
A scanning confocal probe, further comprising a light condensing means for condensing the light flux emitted from the polarizing beam splitter on a living tissue in the body cavity. The scanning confocal probe according to claim 2,
A scanning confocal probe, wherein the light condensing means is a diffraction surface provided on the light-emitting end face. The scanning confocal probe according to claim 2 or 3,
The scanning confocal probe, wherein the scanning means is disposed at a position where the light is focused when a parallel light beam is incident on the light-collecting means from the living tissue side. The scanning confocal probe according to any one of claims 1 to 4,
A scanning confocal probe, characterized in that the scanning means has a biaxial scanning mirror for scanning the light beam in a first direction and a second direction orthogonal to the first direction. The scanning confocal probe according to any one of claims 1 to 5,
A scanning confocal probe, wherein the predetermined surface and the light-emitting end surface are parallel to each other. The scanning confocal probe according to any one of claims 1 to 5,
A scanning confocal probe, wherein the predetermined surface is orthogonal to the light emitting end surface. The scanning confocal probe according to any one of claims 1 to 7,
A scanning confocal probe, wherein the polarizing beam splitter is a substantially regular hexahedron. The scanning confocal probe according to any one of claims 1 to 8,
A scanning confocal probe, wherein the polarizing means is a λ / 4 wavelength plate. The scanning confocal probe according to any one of claims 1 to 9,
Among the reflected light reflected by the living tissue, a pinhole arranged to remove reflected light other than reflected light from the object-side focal plane of the light-collecting means,
A scanning confocal probe, 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 condensing means is incident. A scanning confocal probe according to any one of claims 1 to 10,
A light source for irradiating a light beam for illuminating living tissue;
A scanning confocal probe device, comprising: an image signal generating unit that generates an image signal based on reflected light of the living tissue transmitted by the scanning confocal probe.

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