JP2018196750A - Fundus image forming device - Google Patents

Abstract

To provide a fundus image forming device that solves the problem that when an oscillation plane mirror as an optical system mechanically driven is disposed between a first ellipse mirror and a second ellipse mirror, an overall size of the device increases, and maintenance becomes difficult.SOLUTION: In a fundus image forming device 100 that scans the ocular fundus of a subject with a beam light, a first reflector 120 and a second reflector 140 are disposed so that a second focal point of the first reflector and a third focal point of the second reflector coincide with each other. The ocular fundus of the subject is scanned with a beam light incident on the first focal point of the first reflector by a scan member through the first reflector, a half mirror 158, and a fourth focal point of the second reflector.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fundus image forming apparatus.

In a fundus scanning apparatus that scans the retina to form a fundus image of a subject, a laser beam is incident on a first elliptical mirror while being scanned in a vertical direction with a polygonal mirror, and reflected light from the first elliptical mirror is received. There is one in which a vibrating plane mirror is incident on a second elliptical mirror while being scanned in the horizontal direction, and reflected light from the second elliptical mirror is incident on a pupil of the subject (for example, see Patent Document 1).
Patent Document 1 Japanese Translation of PCT Publication No. 2009-543585

  However, in the above fundus scanning apparatus, since the vibration plane mirror as an optical system that is mechanically driven is arranged between the first elliptical mirror and the second elliptical mirror, the entire apparatus becomes larger, There is a problem that maintenance becomes difficult.

  According to a first aspect of the present invention, there is provided a fundus image forming apparatus that scans the fundus of a subject with light beams, and includes a light source that supplies light beams, a first focus, and a second focus. The first reflecting mirror that reflects the incident beam light so as to pass through the second focal point, the third focal point, and the fourth focal point, and reflects the beam light incident on the third focal point so as to pass through the fourth focal point. A second reflecting mirror; a half mirror disposed in an optical path between the first reflecting mirror and the second reflecting mirror; and a scanning member disposed at a first focal point of the first reflecting mirror. The second focal point of the mirror and the third focal point of the second reflecting mirror are arranged so as to coincide with each other, and light beams incident on the first focal point of the first reflecting mirror by the scanning member. The subject's fundus is scanned through the fourth focal point of the two reflectors.

  The outline of the above configuration does not enumerate all the features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

1 is a schematic diagram of a fundus image forming apparatus 100. FIG. FIG. 2 is a schematic diagram illustrating the arrangement of a scanning optical system 112. 2 is a schematic diagram illustrating an example of a two-dimensional scanning unit 130. FIG. FIG. 3 shows a schematic view of another fundus image forming apparatus 170. Furthermore, the schematic of another fundus image forming apparatus 180 is shown.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a schematic view of a fundus image forming apparatus 100. Although the xyz direction is defined in the direction shown in the figure, these are for illustrative purposes, and any of them may be a vertical direction or a horizontal direction.

  The fundus image forming apparatus 100 includes a light source 110, a half mirror 158, a scanning optical system 112, a detector 152, a control unit 154, and an image processing unit 156. The scanning optical system 112 includes a two-dimensional scanning unit 130, a first reflecting mirror 120, a planar reflecting mirror 150, and a second reflecting mirror 140.

  The light source 110 emits beam light 102 that irradiates the eye 10 of the subject. The wavelength of the beam light 102 may be selected according to the inspection target, and is, for example, an infrared region or a visible light region. Although one light source 110 is shown in the example shown in FIG. 1, a plurality of light sources that emit different wavelengths may be used. When a plurality of light sources are used, the light beams from the respective light sources are placed on the same optical path by the beam combiner. In addition, it is more preferable to use laser light as the beam light because the straightness is good.

  The half mirror 158 functioning as a beam splitter transmits and reflects the beam light incident on the half mirror 158 at a ratio designed in advance. The half mirror 158 transmits the beam light 102 from the light source 110 and reflects the beam light 102 returned from the eye 10 to guide it to the detector 152. When the beam light 102 is multicolored, the half mirror 158 may be replaced with a plurality of dichroic mirrors corresponding to the respective wavelengths, and a plurality of detectors that receive reflected light from the respective dichroic mirrors may be provided.

  FIG. 2 is a schematic diagram for explaining the arrangement of the scanning optical system 112. For simplification, the two-dimensional scanning unit 130 is omitted.

  The first reflecting mirror 120 has a first focal point 122 and a second focal point 124. The first reflecting mirror 120 reflects the beam light 102 incident through the first focal point 122 so as to pass through the second focal point 124. An example of the first reflecting mirror 120 is an ellipsoidal reflecting mirror whose reflecting surface is a part of a spheroid obtained by rotating an ellipse having the first focal point 122 and the second focal point 124 as major axes around the major axis. .

  The second reflecting mirror 140 has a third focal point 142 and a fourth focal point 144. The second reflecting mirror 140 reflects the beam light 102 incident through the third focal point 142 so as to pass through the fourth focal point 144. An example of the second reflecting mirror 140 is an ellipsoidal reflecting mirror whose reflecting surface is a part of a spheroid obtained by rotating an ellipse having the major axis of the third focal point 142 and the fourth focal point 144 around the major axis. .

  The position of the third focal point 142 of the second reflecting mirror 140 and the position of the second focal point 124 of the first reflecting mirror 120 include the case where the respective positions completely coincide as shown in FIG. The above is the same, but includes the case where it inevitably deviates due to assembly errors.

  The plane reflecting mirror 150 is disposed at the position of the second focal point 124 of the first reflecting mirror 120. In the example shown in FIG. 2, the plane reflecting mirror 150 is a plane mirror, and the reflecting surface thereof is disposed so as to pass through the second focal point 124 and may be fixed at least during scanning of the beam light 102. It also includes being moved for optical adjustment after scanning. Ideally, the positional relationship between the plane reflecting mirror 150 and the first focal point 122, and the positional relationship between the second focal point 124 of the first reflecting mirror 120 and the third focal point 142 of the second reflecting mirror 140 are ideal. Although it is preferable to match each other, these positional relationships are allowed to match within a predetermined range. The range is a range in which, when the angle of the beam light is two-dimensionally scanned at the iris position of the eye to be examined, the scan beam light enters the eye pupil and does not interfere with the formation of the fundus image. It has become.

  The direction of the normal line C of the plane reflecting mirror 150 includes a line segment A connecting the first focus 122 and the second focus 124 and a line segment B connecting the third focus 142 and the fourth focus 144. Arranged in a direction that bisects the angle. Thereby, the planar reflecting mirror 150 reflects the beam light 102 reflected by the first reflecting mirror 120 toward the second reflecting mirror 140. In addition, when the line segment A and the line segment B are parallel, the direction orthogonal to those line segments should just be made into the normal line C.

  Note that the position of the plane reflecting mirror 150 can be minimized by being coincident with the second focal point 124 (third focal point 142) as illustrated. However, the position of the plane reflecting mirror 150 can be arranged away from the second focal point 124 (third 1422) as long as the above-described orientation is maintained. That is, for example, in the configuration shown in FIG. 2, the planar reflecting mirror 150 is translated to an arbitrary position unless the scanning beam light guided from the first reflecting mirror to the second reflecting mirror is partially blocked. Is possible. In this case, needless to say, the focal point of the other reflecting mirror coincides with the imaginary focal point of one reflecting mirror formed by the reflection of the planar reflecting mirror 150.

  The first reflecting mirror 120 and the second reflecting mirror 140 are arranged so that the reflecting surfaces and the rotation axes thereof are in the same direction, that is, the rotation axes are arranged substantially on the −y side with respect to the reflecting surfaces. In other words, due to the presence of the planar reflecting mirror 150, the first reflecting mirror 120 and the second reflecting mirror 140 are not opposed to each other. 2 and other drawings, the first reflecting mirror 120, the second reflecting mirror 140, and the like are shown as cross sections cut along a zy plane including the major axis.

  The spheroid of the first reflecting mirror 120 and the spheroid of the second reflecting mirror 140 have the same eccentricity. Since the eccentricity is equal to each other, the uniformity of the angle scanning of the light beam is maintained, and the fundus image obtained by the light beam scanning is not distorted. This will be described later. Further, the first reflecting mirror 120 and the second reflecting mirror 140 may be equal in size or different from each other as long as the light within a scanning range set by the two-dimensional scanning unit 130 can be reflected. May be. In the example of FIG. 2, the first reflecting mirror 120 on the side close to the light source 110 is smaller than the second reflecting mirror 140 on the side close to the eye 10. Thereby, the whole apparatus can be reduced in size.

  FIG. 3 is a schematic diagram illustrating an example of the two-dimensional scanning unit 130. The two-dimensional scanning unit 130 is rotatable about the x axis with respect to the main body 131, the frame 133 supported by the connecting portion 132 so as to be rotatable about the z axis with respect to the main body 131, and the frame 133. And a reflecting mirror 135 that is supported by the connecting portion 134 and reflects the beam light. The two-dimensional scanning unit 130 has a so-called gimbal structure, and is configured by, for example, MEMS, and is electrostatically driven by the control unit 154, for example.

  In the above configuration, the pupil 12 of the subject coincides with the fourth focus 144 of the second reflecting mirror 140 within a predetermined range (a range in which the light beam enters when the eye is placed near the fourth focus). So positioned. The control unit 154 emits the beam light 102 from the light source 110 and controls the amount of rotation of the two-dimensional scanning unit 130 to rotate the reflecting mirror 135 about the z axis and the x axis, thereby causing the light source 110 to emit light. The beam light 102 is scanned in the z direction and the x direction.

  The beam light 102 from the two-dimensional scanning unit 130 is reflected in the order of the first reflecting mirror 120, the planar reflecting mirror 150, and the second reflecting mirror 140, and reaches the retina through the pupil 12. The beam light 102 reflected from the retina traces the optical path in the reverse direction and reaches the half mirror 158. The light beam 102 reflected by the half mirror 158 is detected by the detector 152. The image processing unit 156 reconstructs the retina image two-dimensionally based on the amount of rotation of the two-dimensional scanning unit 130 controlled by the control unit 154 and the amount of light detected by the detector 152, and displays it on a monitor or the like. Output.

Here, the relationship between the change in the angle of the beam light emitted from the first focus 122 by the two-dimensional scanning unit 130 and the change in the angle of the beam light reflected by the first reflecting mirror 120 and incident on the second focus 124 will be considered. For example, as shown in FIG. 1, when the two-dimensional scanning unit 130 scans the beam light by an angle change θ ₁₁ around the x axis from a certain angle, the same angle change θ ₁₂ (that is, θ ₁₁₎ around the x axis. Suppose that the beam light is scanned by = θ ₁₂ ).

Since the change in the curvature of the reflection portion of the first reflecting mirror 120 is different in the above scanning, the respective angle changes θ ₂₁ and θ ₂₂ toward the second focus 124 with respect to the same angle changes θ ₁₁ and θ ₁₂ . Are generally different (ie, θ ₂₁ ≠ θ ₂₂ ). Each of the angles can be calculated geometrically, but θ ₂₁ <θ ₂₂ in the example of FIG.

In other words, the ratio between the angle change of the beam light emitted from the first focus 122 and the angle change of the beam light reflected by the first reflecting mirror 120 and incident on the second focus 124 corresponding to the angle change is non-uniform. (Θ ₁₁ / θ ₁₂ ≠ θ ₂₁ / θ ₂₂ ).

The incident angle and the reflection angle are equal to the plane mirror. Therefore, if the angle changes of the reflection at the planar reflecting mirror 150 with respect to the angle changes θ ₂₁ and θ ₂₂ are θ ₃₁ and θ ₃₂ , respectively, θ ₂₁ = θ ₃₁ and θ ₂₂ = θ ₃₂ are obtained.

In the present embodiment, the spheroid of the first reflecting mirror 120 and the spheroid of the second reflecting mirror 140 have the same eccentricity, and the plane reflecting mirror 150 has a normal C direction in the direction of the line. The angle formed by the segment A and the segment B is arranged in a direction that bisects the angle. From the above, θ ₁₁ / θ ₁₂ = θ ₄₁ / θ ₄₂ is obtained. In other words, the ratio between the change in the angle of the beam light emitted from the first focus 122 and the change in the angle of the beam light incident on the fourth focus 144 corresponding to the change in angle is uniform. Obviously, θ ₁₁ = θ ₄₁ and θ ₁₂ = θ ₄₂ .

  According to the above configuration, the two-dimensional image of the retina can be reconstructed without distortion with respect to the rotation amount of the two-dimensional scanning unit 130. Further, since the two-dimensional scanning unit 130 is responsible for two-dimensional scanning, and the shared focal point of the first reflecting mirror 120 and the second reflecting mirror 140 has no mechanically movable part during scanning, the entire apparatus is Simplification and miniaturization can be achieved.

  FIG. 4 is a schematic view of another fundus image forming apparatus 170. In the fundus image forming apparatus 170, the same components as those in the fundus image forming apparatus 100 in FIG.

  The scanning optical system 173 of the fundus image forming apparatus 170 has a half mirror 172 at the position and the direction instead of the plane reflecting mirror 150 of FIG. The half mirror 172 reflects the beam light 102 from the first reflecting mirror and guides it to the second reflecting mirror 140, and also reflects a part of the beam light 102 from which the reflected light from the fundus returns through the second reflecting mirror 140. To Penetrate.

  Furthermore, in place of the detector 152 of the fundus image forming apparatus 100, the fundus image forming apparatus 170 is provided with a light intensity sensor 174 on the opposite side of the half mirror 172 from the second reflecting mirror 140. The light intensity sensor 174 (eg, a photodiode) detects the intensity of the beam light 102 that has passed through the half mirror 172.

  With the above configuration, the retina image can be generated based on the light intensity detected by the light intensity sensor 174 in response to the two-dimensional scanning of the beam light 102 by the two-dimensional scanning unit 130. As for the position of the half mirror 172, the arrangement direction of the line segment A connecting the first focal point 122 and the second focal point 124 is similar to that of the planar reflecting mirror 150 shown in FIGS. As long as the angle formed by the line segment B connecting the three focal points 142 and the fourth focal point 144 is arranged in a direction that bisects the angle, the focal points can be arranged out of the focal position.

  FIG. 5 shows a schematic view of still another fundus image forming apparatus 180. In the fundus image forming apparatus 170, the same components as those in the fundus image forming apparatus 100 in FIG.

  In the scanning optical system 184 of the fundus image forming apparatus 180, the first reflecting mirror 120 and the second reflecting mirror 140 are arranged to face each other. The second focal point 124 of the first reflecting mirror 120 and the third focal point 142 of the second reflecting mirror 140 are arranged on the same straight line. In other words, the rotation axes of the elliptical mirror as the first reflecting mirror 120 and the elliptical mirror as the second reflecting mirror 140 coincide. In this configuration, unlike the fundus image forming apparatus 100, no optical member is disposed in the optical path reaching the first reflecting mirror 120 and the second reflecting mirror 140.

  With the above configuration, a two-dimensional image of the retina can be reconstructed without distortion using fewer optical members.

  In any of the above-described embodiments, the first reflecting mirror 120 and the second reflecting mirror 140 have a shape in which a part of the spheroid is a reflecting surface. One or both of these may be replaced with other shapes. For example, a part of the first paraboloid rotating body having the first focal point 122 as a focal point and a part of the second paraboloid rotating body having the second focal point 124 as a focal point are combined to form the first reflecting mirror 120. Also good. Similarly, the second reflecting mirror 140 may be a combination of a part of two paraboloid rotating bodies.

  In the configuration of the above embodiment, elliptical mirrors having the same eccentricity are used as the first reflecting mirror 120 and the second reflecting mirror 140, respectively. However, the configuration is configured by combining two parabolic mirrors and a two-dimensional scanning mirror. It is also possible to do. The two-dimensional scanning mirror of the beam light is placed on the focal point of the first parabolic mirror, and the pupil 12 of the subject is positioned at the focal position of the next parabolic mirror. In the reflection of one parabolic mirror, the angle scanning of the beam light is non-uniform, as in the case of one elliptical mirror, but by combining two identical parabolic mirrors, the angular scanning of the beam light is non-uniform. It is possible to cancel the sex. Also with this configuration, it is possible to obtain a clear image with little distortion in the fundus image.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

  10 eyes, 12 pupils, 100 fundus image forming apparatus, 102 beam light, 110 light source, 112 scanning optical system, 120 first reflecting mirror, 122 first focus, 124 second focus, 130 two-dimensional scanning unit, 131 main body, 132 Connecting part, 133 frame, 134 connecting part, 135 reflecting mirror, 140 second reflecting mirror, 142 third focus, 144 fourth focus, 150 plane reflecting mirror, 152 detector, 154 control part, 156 image processing part, 158 Half mirror, 170 fundus image forming apparatus, 172 half mirror, 173 scanning optical system, 174 light intensity sensor, 180 fundus image forming apparatus, 184 scanning optical system

Claims (9)

A fundus image forming apparatus that scans the fundus of a subject with beam light,
A light source for supplying the light beam;
A first reflecting mirror having a first focal point and a second focal point, and reflecting the beam light incident on the first focal point so as to pass through the second focal point;
A second reflecting mirror having a third focus and a fourth focus, and reflecting the beam light incident on the third focus so as to pass through the fourth focus;
A half mirror disposed in an optical path between the first reflecting mirror and the second reflecting mirror;
A scanning member disposed at the first focal point of the first reflecting mirror,
The second focal point of the first reflecting mirror and the third focal point of the second reflecting mirror are aligned with each other;
The scanning light is incident on the first focal point of the first reflecting mirror by the scanning member, and passes through the fourth focal point of the subject through the first reflecting mirror, the half mirror, and the second focal point of the subject. A fundus image forming apparatus that scans the fundus.   The fundus image forming apparatus according to claim 1, wherein the half mirror transmits a part of light on an optical path passing through the second reflecting mirror.   3. The fundus image forming apparatus according to claim 1, further comprising a detection unit configured to detect the beam light transmitted through the half mirror on an optical path of the half mirror passing through the second reflecting mirror.   The fundus image forming apparatus according to claim 3, further comprising an image processing unit that generates a retina image based on a signal from the detection unit.   The half mirror has a normal as a direction that bisects an angle formed by a line segment connecting the first focus and the second focus and a line segment connecting the third focus and the fourth focus. The fundus image forming apparatus according to any one of claims 1 to 4.   The fundus image forming apparatus according to claim 1, wherein each of the first reflecting mirror and the second reflecting mirror has a part of a spheroid as a reflecting surface.   The fundus image forming apparatus according to claim 6, wherein the first reflecting mirror and the second reflecting mirror have a part of a spheroid having an equal eccentricity as a reflecting surface.   The fundus image forming apparatus according to claim 1, wherein the first reflecting mirror is smaller than the second reflecting mirror.   The fundus image forming apparatus according to any one of claims 1 to 8, wherein the half mirror transmits and reflects incident light at a predesigned rate.

Images