JP2006314650A - Ophthalmic photography apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fundus photography apparatus which achieves downsizing and cost reduction with a simple structure, facilitates optical adjustment, and allows a user to perform satisfactorily simultaneous stereoscopic photography of the fundus. <P>SOLUTION: A photographing diaphragm 12 has openings 12a and 12b disposed at a position P substantially conjugate to the anterior ocular segment of the eye being examined. The photographing diaphragm is arranged on an object-side focal plane of an image-forming lens 13, and a lattice barrier 15 is arranged on an image-side focal plane of the image-forming lens. A fundus image is guided via the lattice barrier to an imaging plane of an imaging CCD 16. In the apparatus, the photographing diaphragm 12, the image-forming lens 13, the lattice barrier 15 and the CCD 16 are moved as a unit for focus adjustment. With such a configuration, the photographing diaphragm is always positioned on the object-side focal plane of the image-forming lens 13, and the optical system is kept telecentric even when the focus is adjusted in accordance with the diopter of the eye being examined. This eliminates a phenomenon of a stereoscopic view that becomes more concave or convex in the periphery of a screen. In addition, crosstalk of the right and left fundus images on an imaging plane is eliminated by arranging the lattice barrier, and a good fundus image for stereoscopic viewing is obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ophthalmologic photographing apparatus, and more particularly to an ophthalmic photographing apparatus provided with a photographing optical system capable of stereoscopic photographing a fundus of a subject's eye.

  In the conventional simultaneous stereoscopic fundus camera, as described in Patent Documents 1 and 2 below, the left and right images are positioned at a position conjugate with the anterior eye portion of the eye to be examined (conjugated with the pupil) with respect to the objective lens. A two-hole aperture having two left and right holes (openings) is provided, and each light beam from the fundus that has passed through the two holes is divided into two optical paths by a prism or the like, and a pair of right and left links The image is guided to each of the image optical systems, and is imaged on the film surface or on the left and right separate areas of the image pickup surface of the image pickup device or on the left and right image pickup devices.

  Further, Patent Document 3 discloses a configuration in which a fundus image is alternately incident on pixels of an image sensor and a stereoscopic image is captured using a cylindrical lens.

There is also known an ophthalmologic photographing apparatus that moves in conjunction with a focusing lens while maintaining a photographing aperture for removing reflected light from the anterior ocular segment to be examined at a position almost conjugate with the anterior ocular segment to be examined. (Patent Document 4).
Japanese Patent No. 2644217 Japanese Patent No. 2933995 Japanese Patent Laid-Open No. 10-165372 JP 2004-208744 A

  However, in the conventional configurations such as Patent Documents 1 and 2, since it is necessary to arrange the lenses of the pair of left and right imaging optical systems in the two left and right optical paths, the configuration is complicated and the apparatus becomes large, There is a problem that the optical adjustment of the left and right optical paths is complicated and takes time to adjust. In addition, since the left and right images are separately formed on the left and right regions or elements, there is a problem that it is necessary to accurately align the left and right images later.

  Also, in the configuration of Patent Document 3 and the like, two images (right image and left image) from the two-hole aperture are made to enter the pixels alternately in the imaging device. The right image and the left image are incident, and there is a problem that good stereoscopic viewing cannot be performed.

  Further, in the stereoscopic imaging of the fundus, it is necessary to consider the diopter difference of the eye to be examined. And the conjugate relationship with each other is broken, and the light that has passed through each hole of the two-hole aperture is not regularly guided alternately to the pixels of the image sensor.

  Even if a two-hole aperture is arranged on the image side focal plane of the focusing lens and a two-hole aperture is arranged on the object side focal plane of the imaging lens to constitute an image side telecentric optical system, the reference diopter (0 diopter) is telecentric on the image side, so accurate stereoscopic viewing is possible, but if the diopter is shifted to the plus side or minus side, the telecentric optical system cannot be maintained during focus adjustment, and the screen There is a problem that the periphery is stereoscopically viewed concavely or convexly.

  Therefore, the present invention solves the above-described problems, and can reduce the size and cost of the apparatus with a simple structure, and can easily perform optical adjustment, so that fundus photographing can be performed satisfactorily. It is an object to provide an apparatus.

The present invention is an ophthalmologic photographing apparatus for photographing an eye fundus to be examined with an electronic imaging means,
An objective lens that images reflected light from the fundus of the eye to be examined;
A first imaging lens disposed behind the objective lens;
A photographing aperture disposed on the image side focal plane of the first imaging lens;
A second imaging lens arranged so that the object-side focal plane coincides with the position of the photographing aperture;
An optical element that is disposed on the image side focal plane of the second imaging lens and guides the fundus image to an electronic imaging unit disposed at a position conjugate with the fundus;
A moving means for integrally moving the first imaging lens, the photographing aperture, the second imaging lens, the optical element, and the electronic imaging means along the optical axis;
The object-side focal plane of the objective lens coincides with the anterior ocular segment to be examined, and the first imaging lens, imaging diaphragm, second imaging lens, optical element, and electronic imaging means are integrated along the optical axis. It is characterized in that the focus adjustment is performed by moving the lens.

  According to the present invention, even when focus adjustment is performed according to the diopter difference of the eye to be inspected, the position of the imaging diaphragm arranged at a position conjugate with the anterior eye portion is always the object side of the second imaging lens. Since the telecentric optical system is maintained in the focal plane, there is no phenomenon of being stereoscopically viewed in a concave or convex shape at the periphery of the screen, and fundus images for the right eye and the left eye are displayed in a predetermined manner. By disposing the optical element that leads to the pixel column in front of the imaging unit, the right and left fundus images do not crosstalk on the imaging surface, and a good stereoscopic fundus image can be obtained.

  The present invention is an ophthalmologic photographing apparatus capable of performing stereo photography for stereoscopic viewing, and the present invention will be described in detail based on an embodiment in which the ophthalmologic photographing apparatus is a fundus camera with reference to the accompanying drawings.

  The fundus camera shown in FIG. 1 is provided with an illumination optical system that illuminates the fundus Er of the eye E, an imaging optical system that captures the illuminated fundus, and an observation optical system that observes the fundus. In the illumination optical system, the light emitted from the light source 1 such as a halogen lamp and the light reflected by the concave mirror 2 become infrared light through the visible cut infrared transmission filter 3 and pass through the strobe 4 and the condenser lens 5. The stereoscopic slit 6 arranged at a position conjugate with the anterior eye part (pupil) Ep of the eye E is illuminated. The illumination light from the slit 6 passes through the lens 7, is reflected by the perforated total reflection mirror 8 having a hole in the center, passes through the objective lens 9, and passes from the anterior segment Ep of the eye E to the fundus Er. Incident light and illuminate the fundus Er with infrared light.

  The reflected light from the fundus Er passes through the hole of the objective lens 9 and the perforated total reflection mirror 8 and passes through the imaging mask 10 that determines the imaging range on the fundus to the first imaging lens 11 as the focusing lens. Incident. The imaging mask 10 is disposed at a fundus conjugate position R between the objective lens 9 and the first imaging lens 11, and two circular apertures 12 a, An imaging stop (two-hole stop) 12 that has 12b and removes reflected light from the anterior segment is disposed. The fundus image that has passed through the photographing aperture 12 is separated into a right-eye light beam and a left-eye light beam by the openings 12 a and 12 b of the photographing aperture 12 and then enters the second imaging lens 13. The photographing aperture 12 is disposed on the object-side focal plane of the second imaging lens 13, and the light beam that has passed through the second imaging lens 13 is reflected by the return mirror 14 and is conjugated with the fundus Er and the imaging mask 10. The light enters the observation CCD 17 having sensitivity to the infrared light arranged at the position.

  When the return mirror 14 leaves the optical path, the light flux from the fundus enters the imaging CCD 16 sensitive to visible light as electronic imaging means arranged at a position conjugate with the fundus Er and the imaging mask 10. The photographing CCD 16 has a large number of pixels arranged in a matrix, and a lattice barrier 15 as an optical element is disposed in the vicinity of the imaging surface of the photographing CCD 16. The grating barrier 15 is a grating-type light shielding plate in which a plurality of slit-like openings are arranged in parallel at equal intervals, and is arranged on the image side focal plane of the second imaging lens 13. On the object-side focal plane, the photographing aperture 12 is arranged as described above to constitute a telecentric optical system.

  In FIG. 1, the photographing aperture 12 is illustrated so as to divide the light beam vertically in the drawing, and the extending direction of the slits of the grating barrier 15 is illustrated in a direction perpendicular to the paper surface. Actually, the photographing aperture 12 divides the light beam in the left-right direction (direction perpendicular to the paper surface in FIG. 1), and each slit of the lattice barrier 15 extends in a direction parallel to the paper surface.

  FIGS. 2 and 3 show the light path of the pupil image and the fundus image. To avoid complexity, the illumination optical system, the return mirror, and the observation optical system of the observation CCD 17 shown in FIG. 1 are omitted. ing.

  When the alignment is completed, the object-side focal plane of the objective lens 9 becomes the anterior segment Ep or in the vicinity thereof, and the ray path of the pupil image at that time is shown in FIGS. 2 (A) and 3 (A). It is shown. Since the anterior eye portion is on the object side focal plane of the objective lens 9, the light beam forming the pupil image that has passed through the objective lens 9 becomes a telecentric light beam, and the pupil image is imaged by the first imaging lens 11. An image is formed at the position of the photographing aperture 12 arranged on the side focal plane. Therefore, the photographic stop 12 is at a position P conjugate with the pupil, and the photographic stop 12 is disposed on the object-side focal plane of the second imaging lens 13, and thus has passed through the second imaging lens 13. The light beam becomes a telecentric light beam. 2A shows light rays along the optical axis, the imaging aperture 12 is shown as a one-hole aperture with a hole in the center for convenience.

  On the other hand, the light path of the fundus image is shown in FIGS. 2B and 3B, and focus adjustment (focus adjustment) is performed at the position of the fundus image where the imaging mask 10 is formed by the objective lens 9. Thus, the fundus image is formed on the photographing CCD 16. Since the position of the fundus image formed by the objective lens 9 varies depending on the diopter of the eye to be examined, the imaging lens is moved in the optical axis direction so that the fundus image is formed on the photographing CCD 16. In the present invention, in order to maintain the pupil conjugate relationship shown in FIGS. 2A and 3A and the image-side telecentric optical system in the second imaging lens, The imaging lens 11, the imaging aperture 12, the second imaging lens 13, the grating barrier 15, the imaging CCD 16, and the return mirror 14 and the observation CCD 17 constituting the observation optical system shown in FIG. As indicated by a double arrow line, it is moved integrally in the optical axis direction by a moving means 20 such as a manual or motor drive. A portion moved by the moving means 20 is shown surrounded by a one-dot chain line in FIGS. 1 to 3, and in FIGS. 1 to 3, the position conjugate with the fundus is R and conjugate with the pupil. The position is indicated by P.

  Further, the configuration after the photographing aperture 12 is shown in detail in FIGS. As shown in FIG. 4, in the lattice barrier 15, the width H of each slit 15a extending perpendicularly to the paper surface is approximately the same as the pixel width H of the photographing CCD 16, and the slit pitch P of the lattice barrier 15 is the photographing. The pixel pitch of the CCD 16 is doubled, and the center position of each slit 15a of the lattice barrier 15 is arranged so as to substantially coincide with the boundary position between two adjacent pixels of the photographing CCD 16. In the same figure, D indicates the distance between the two apertures 12a and 12b of the photographing aperture 12, that is, the pupil division distance, and f indicates the focal length of the second imaging lens 13. As described above, The photographing aperture 12 is disposed on the object-side focal plane of the second imaging lens 13, and the grating barrier 15 is disposed on the image-side focal plane.

  In such a configuration, alignment is performed by turning on the light source 1, illuminating the fundus Er of the eye E with infrared light, and guiding the reflected light from the fundus to the observation CCD 17 and observing the image. Further, the moving means 20 moves the portions 10 to 17 surrounded by the one-dot chain line in FIGS. 1 to 3 along the optical axis to perform focusing.

  As shown in FIGS. 2 (A) and 3 (A), the alignment is performed so that the object-side focal plane of the objective lens 9 coincides with or is in the vicinity of the anterior segment (pupil) position. Is called. Further, focusing is performed by the moving means 20 using the imaging mask 10, the first imaging lens 11, the imaging aperture 12, the second imaging lens 13, the grating barrier 15, the imaging CCD 16, the return mirror 14, and the observation mirror. The CCD 17 is moved integrally so that the photographing mask 10 is positioned at the position of the fundus image formed by the objective lens 9 as shown in FIGS. 2 (B) and 3 (B). At this time, since the imaging mask 10 has a conjugate relationship between the observation CCD 17 and the imaging CCD 16, a clear fundus image is formed on the observation CCD 17 and it can be confirmed that the focus is in focus. When the return mirror 14 is separated from the optical path, a clear fundus image is taken on the photographing CCD 16.

  Thus, when the alignment and focusing are completed, the return mirror 14 is detached from the optical path, and the strobe 4 is emitted. The light flux from the fundus illuminated by the strobe light passes through the objective lens 9, the hole of the perforated total reflection mirror 8, the imaging mask 10, and the first imaging lens 11, and enters the imaging aperture 12. The light beam for right eye and the light beam for left eye are separated by 12a and 12b.

  As shown in FIG. 5A, the right-eye light beam (pupil image) indicated by the solid line passing through the opening 12a passes through the second imaging lens 13, and then becomes a substantially parallel light beam (telecentric light beam). After entering the slit 15a of the grating barrier 15, it enters the right eye pixel columns (portions filled with dots) R1 to R5 of the photographing CCD 16 shown in FIG. Further, the light beam (pupil image) for the left eye indicated by the dotted line passing through the opening 12 b passes through the second imaging lens 13 and becomes a substantially parallel light beam and a telecentric light beam. After entering the lens 15a, the light enters the left-eye pixel columns (white portions) L1 to L5 of the photographing CCD 16.

  Further, as shown in FIG. 5B, the fundus image for the right eye that passes through the opening 12a is formed on the pixel rows R1 to R5 of the photographing CCD 16, and the fundus for the left eye that passes through the opening 12b. An image is formed on the pixel rows L1 to L5. The arrangement of the pixel rows R1 to R5; L1 to L5 of the photographing CCD 16 is schematically shown in FIG.

  As described above, in the present invention, the focus adjustment is performed by the imaging mask 10, the first and second imaging lenses 11, 13, the imaging aperture 12, the grating barrier 15, and the imaging CCD 16 (and the return mirror 14 and the observation CCD 17). For example, even if the focus adjustment is performed according to the individual difference in the diopter of the eye to be examined, the position P (position of the photographing aperture 12) conjugate with the anterior eye portion is always the second. Since the telecentric optical system is maintained on the object side focal plane of the imaging lens 13, the phenomenon of being stereoscopically viewed in a concave shape or a convex shape in the periphery of the screen even on a flat surface is eliminated. Further, by arranging the lattice barrier 15 having the size as shown in FIG. 4 in the vicinity of the front surface of the photographing CCD 16, the fundus image that has passed through the one opening 12a of the photographing diaphragm 12 can be obtained. The fundus image that is incident on the right-eye pixel rows R1 to R5 and is not incident on the left-eye pixel rows L1 to L5 and passes through the other opening 12b is a left-eye pixel. Since it enters the rows L1 to L5 and does not enter the pixel rows R1 to R5 for the right eye, the right and left fundus images do not crosstalk on the imaging surface of the CCD, and good for stereoscopic viewing. Can be obtained.

  Note that the above-described grating barrier is an optical element made of a grating-type light shielding plate, but a lenticular type optical element can also be used instead, and examples thereof are shown in FIGS. 7A and 7B. Has been. In FIG. 7A, the lenticular prism 30 is used, the prism pitch (distance between the prism valleys) P is twice the pixel width H, and the apex of each prism 30a is adjacent to the CCD 16 for photographing. It arrange | positions so that the boundary between two pixels may correspond and the vertex of each prism 30a may be located in the image side focal plane of the 2nd imaging lens 13. FIG. FIG. 7B shows a case where a lenticular lens 31 is used. The lens pitch (distance between the valleys of the lens) P is twice the pixel width H, and the apex of each lens 31 a is that of the photographing CCD 16. They are arranged so as to coincide with the boundary between two adjacent pixels and so that the apex of each lens 31a is located on the image side focal plane of the second imaging lens 13. In any configuration, the fundus image that has passed through one aperture 12a of the photographing aperture 12 is deflected by the prism surface or the lens surface, and is imaged on the right-eye pixel row (shaded portion) every other row, The fundus image that has passed through the opening 12b is imaged on the left-eye pixel row (white portion) every other row, and the same effect is obtained when a lattice barrier is used.

  When a single-plate color CCD is used as the imaging means, each pixel usually has a color sensitivity as shown in FIG. 6B by a three-color filter. With such color characteristics, when the right eye image and the left eye image are obtained in every other pixel row as described above, for example, the left eye image is R and G, and the right eye image is , G and B, resulting in images of different colors on the left and right. Therefore, as shown in FIG. 6B, the fundus image from one aperture 12a of the photographing aperture is converted into two adjacent pixel rows (dots) of the color CCD 16 'by a lattice barrier (or lenticular lens or lenticular prism). The fundus image from the other opening 12b is guided to the two pixel columns (white portion) between them. For this reason, when a lattice slit is used, the slit width is doubled (2H), and the slit pitch is also doubled (4H). When a lenticular prism or a lenticular lens is used, the prism pitch or the prism pitch is doubled (4H). By doing in this way, the image of the same hue can be acquired on the left and right. Note that a pixel having R sensitivity in FIG. 6B also receives light in the infrared region.

  In the above embodiment, the image captured by the photographing CCD 16 can be displayed in a stereoscopic manner on a display means such as a commercially available lenticular monitor or a parallax barrier monitor, and is stereoscopically viewed using polarized glasses. be able to.

  In the above-described embodiment, the imaging diaphragm 12, the grating barrier 15, the lenticular prism 30, or the lenticular lens 31 disposed in front of the imaging CCD 16 can be detachably provided on the optical path. In that case, monocular imaging can be performed by detaching these elements from the optical path. In this case, the photographing diaphragm 12 is replaced with a one-hole photographing diaphragm, and the slit 6 disposed in the illumination optical system is replaced with a monocular illumination slit.

It is an optical arrangement | positioning figure which showed the optical system of the ophthalmologic imaging device of this invention. (A) is explanatory drawing which shows the light path of a pupil image, (B) is explanatory drawing which shows the light path of a fundus image. (A) is explanatory drawing which shows the path | route of the chief ray on the basis of a pupil image, (B) is explanatory drawing which shows the path | route of the chief ray on the basis of a fundus image. It is explanatory drawing which showed in detail the path | route of the light ray which passes the opening of an imaging stop. (A) is an explanatory view showing a ray path of a pupil image passing through the aperture of the imaging stop, and (B) is an explanatory view showing a ray path of a fundus image passing through the opening of the imaging aperture. (A) is explanatory drawing which shows arrangement | positioning of the pixel row | line | column of imaging CCD, (B) is explanatory drawing which shows arrangement | positioning of the pixel row | line of color CCD. It is explanatory drawing which shows a light beam path when a lenticular type optical element is arrange | positioned in front of CCD for imaging | photography.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 Objective lens 10 Imaging mask 11 1st imaging lens 12 Imaging diaphragm 13 2nd imaging lens 15 Lattice barrier 16 CCD for imaging | photography
17 CCD for observation
20 Moving means 30 Lenticular prism 31 Lenticular lens

Claims (8)

An ophthalmologic photographing apparatus for photographing an eye fundus of a subject with an electronic imaging means,
An objective lens that images reflected light from the fundus of the eye to be examined;
A first imaging lens disposed behind the objective lens;
A photographing aperture disposed on the image side focal plane of the first imaging lens;
A second imaging lens arranged so that the object-side focal plane coincides with the position of the photographing aperture;
An optical element that is disposed on the image side focal plane of the second imaging lens and guides the fundus image to an electronic imaging unit disposed at a position conjugate with the fundus;
A moving means for integrally moving the first imaging lens, the photographing aperture, the second imaging lens, the optical element, and the electronic imaging means along the optical axis;
The object-side focal plane of the objective lens coincides with the anterior ocular segment to be examined, and the first imaging lens, imaging diaphragm, second imaging lens, optical element, and electronic imaging means are integrated along the optical axis. The ophthalmologic photographing apparatus is characterized in that the focus adjustment is performed by moving it with the lens.   The photographing aperture is a diaphragm having two apertures, and the optical element guides the fundus image from one aperture of the imaging aperture to every other pixel column of the electronic imaging unit, and the fundus image from the other aperture. The ophthalmologic photographing apparatus according to claim 1, wherein the first to second pixel lines are led to a pixel line between every other pixel line.   The photographing aperture is a diaphragm having two apertures, and the optical element guides the fundus image from one aperture of the imaging aperture to every two adjacent pixel columns of the electronic imaging unit, and the other aperture. 2. The ophthalmologic photographing apparatus according to claim 1, wherein the fundus image is guided to two pixel columns between the two pixel columns.   The ophthalmologic photographing apparatus according to any one of claims 1 to 3, wherein a photographing mask for determining a photographing range on the fundus is arranged at a fundus conjugate position in front of the first imaging lens.   The ophthalmologic photographing apparatus according to claim 4, wherein the photographing mask is moved in conjunction with a moving means.   The ophthalmologic photographing apparatus according to any one of claims 1 to 5, wherein the photographing aperture and the optical element are provided so as to be detachable from an optical path.   The ophthalmologic photographing apparatus according to any one of claims 1 to 6, wherein the optical element is a lattice type light shielding plate having a plurality of slit-shaped openings.   The ophthalmologic photographing apparatus according to any one of claims 1 to 6, wherein the optical element is a lenticular optical element.

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