JP2011050445A - Ophthalmologic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To observe or capture an appropriate cross-sectional image of an anterior ocular segment by projecting slit light with little unevenness of luminance. <P>SOLUTION: The ophthalmologic apparatus includes a projecting optical system having an illumination light source and a mask with a slit opening for projecting slit light toward the anterior ocular segment to be examined, and observes or captures a cross-sectional image of the anterior ocular segment by slit light. The projecting optical system includes a light scanning means for scanning in the longitudinal direction of the slit with the light emitted from the illumination light source. The ophthalmologic apparatus further includes an imaging optical system having an imaging element for capturing the cross-sectional image of the anterior ocular segment with the slit light. The light scanning means performs scanning at least once at a rate faster than a frame rate of the imaging element. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ophthalmologic apparatus for observing or photographing an anterior segment cross-sectional image.

  In an apparatus for projecting slit light onto the subject's eye and observing or photographing an anterior segment cross-sectional image, a plurality of light emitting diodes (LEDs) are arranged in the longitudinal direction of the slit in order to compensate for a shortage of light in the peripheral part of the slit light Those arranged in a plane are known. (For example, see Patent Document 1)

JP 2001-87226 A

  However, in the case of the above-described configuration, luminance unevenness may occur in the slit image by arranging a plurality of LEDs. In addition, if one of the plurality of LEDs fails and no longer emits light, it is difficult to notice the failure because the other LEDs can project the slit light itself.

  In view of the above problems, an object of the present invention is to provide an ophthalmologic apparatus capable of projecting slit light with little luminance unevenness and observing or photographing a suitable anterior segment cross-sectional image.

  In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) An illumination light source and a mask having a slit opening are provided, and a projection optical system that projects slit light toward the anterior ocular segment to be examined is provided, and an anterior segment cross-sectional image by the slit light is observed. Or in an ophthalmic device for photographing,
The projection optical system includes an optical scanning unit that scans light emitted from the illumination light source in a longitudinal direction of the slit.
(2) In the ophthalmic apparatus according to (1),
An imaging optical system having an imaging element that captures a cross-sectional image of the anterior segment by the slit light;
The optical scanning unit performs at least one optical scan at a rate faster than a frame rate of the image sensor.
(3) In the ophthalmologic apparatus of (2),
The optical scanning means is arranged between the illumination light source and the slit.
(4) In the ophthalmic apparatus according to (3),
The illumination light source is a visible light emitting diode.
(5) In the ophthalmic apparatus according to (4),
The light scanning means includes a light reflecting member, a motor, and a piston / crank mechanism connected to the light reflecting member and converting a rotational motion of the motor into a linear motion of the light reflecting member. Ophthalmic equipment.

  According to the present invention, it is possible to project slit light with little luminance unevenness and to observe or photograph a suitable anterior segment cross-sectional image.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a configuration when the optical system of the ophthalmologic apparatus is viewed from above. The present optical system includes an anterior ocular segment measurement optical system 90 for measuring ocular characteristics (for example, anterior chamber depth, corneal thickness, corneal curvature, etc.) of an anterior segment of a subject's eye, and an anterior segment front image. Are roughly divided into an anterior ocular segment imaging optical system 30, a fixation target projection optical system 40, and an alignment projection optical system 50. The following optical system is built in a housing (not shown). Further, the casing is three-dimensionally moved with respect to the subject's eye via an operation member (for example, a joystick) by driving a known alignment moving mechanism.

  The anterior segment measuring optical system 90 projects a slit light toward the anterior segment of the eye to be examined, and receives the anterior segment reflected light from the slit light projected by the projection optical system 90a. An imaging optical system 90b that captures a partial cross-sectional image.

  The projection optical system 90a includes a single illumination light source 91 that emits visible light (for example, a visible light emitting diode (LED)), a condensing lens 93, and a reflective member that can move in the optical axis direction L2 (arrow A direction). In the embodiment, a scanning mirror 94 is used), a moving mechanism 95 having a motor, a slit plate 96 as a mask in which a slit opening is formed, a dichroic mirror 97, a projection lens 47, a visible light reflection / red An externally transmitting dichroic mirror 33, an objective lens 32, and an optical filter 200 are included. The scanning mirror 94 is moved in the direction of the optical axis L2 by a moving mechanism 95 having a motor. In the present embodiment, the condensing lens 93 is used as a collimator lens that uses a divergent light beam emitted from a light source as a parallel light beam.

  The slit plate 96 is disposed at a position conjugate with the anterior eye portion (for example, near the apex of the cornea or the front surface of the crystalline lens), and in FIG. 1, a slit opening whose horizontal direction is the longitudinal direction is formed. The scan mirror 94 is moved in the longitudinal direction of the slit of the slit plate 96 by the moving mechanism 95. In addition, it is better to use a monochromatic green light source or a blue light source as the light source 91, which has excellent scattering characteristics with respect to the anterior segment and reduces the consideration of lens aberration and the like.

  The scan mirror 94 and the moving mechanism 95 are used as an optical scanning unit that scans the light emitted from the light source 91 in the longitudinal direction of the slit. As shown in FIG. 2, the moving mechanism 95 includes a motor 100, a crankshaft 101, a connecting rod 102 that connects the crankshaft 101 and the piston 103, a piston 103, a connecting portion 104 that connects the mirror 94 and the piston 103. It is configured as a piston / crank mechanism. The piston 102 is arranged so that the moving direction is regulated in the direction of arrow A by a predetermined regulating member. When the motor 100 is driven and rotated, the crankshaft 101 and the connecting rod 102 convert the rotation of the motor 100 into linear motion and move the piston 103 in the direction of arrow A. The scanning mirror 94 coupled to the connecting portion 104 moves linearly in the optical axis direction L2 by the linear movement of the piston 103.

  The lenses 47 and 32 are disposed between the light source 91 and the optical filter 200, and condense light from the light source 91 on the cornea.

  The imaging optical system 90b includes a two-dimensional imaging device 99 and an imaging lens 98 that guides the reflected light from the anterior segment by the projection optical system 90a to the imaging device 99. The imaging optical system 90b is an anterior segment cross section based on the Scheimpflug principle. An image is captured. In FIG. 1, for convenience of explanation, the imaging optical system 90b is arranged on the right side when viewed from the subject, but actually, it is arranged below the projection optical system 90a. That is, the imaging optical system 90b is arranged such that its optical axis (imaging optical axis) intersects with the optical axis of the projection optical system 90a at a predetermined angle, and the optical cross section of the projection image by the projection optical system 90a and the object to be examined A lens system including the cornea of the human eye (the cornea and the imaging lens 98) and the imaging surface of the imaging element 99 are arranged in a shine-proof relationship. In this case, an optical arrangement in which a virtual image of an optical cross-sectional image due to the influence of refraction at the cornea, each extended surface of the main plane of the imaging lens 98 and the imaging surface of the imaging element 99 intersect at one intersection line (uniaxial), It has become. 1 shows a configuration in which the imaging optical system 90b is disposed below the projection optical system 90a. However, the configuration is not limited thereto, and the imaging optical system 90b is disposed above, to the right, and to the left of the projection optical system 90a. It may be configured (the slit direction of the slit plate 96 is changed correspondingly). The imaging optical system 90b may be configured to be able to rotate 360 degrees with respect to the optical axis of the projection optical system 90a.

  Note that a filter 92 that transmits only light (blue light) emitted from the light source 91 and used to capture the anterior segment cross-sectional image is disposed in front of the lens 98 (the subject eye E side). Yes.

  The alignment projection optical system 50 is an optical system that has a projection light source 51 (for example, λ = 970 nm) that emits infrared light and projects an alignment index onto the subject's cornea. And the alignment parameter | index projected on the cornea is used for position alignment (for example, automatic alignment, alignment detection, manual alignment, etc.) with respect to a subject's eye. In the present embodiment, the projection optical system 50 is an optical system that projects a ring index on the subject's eye cornea, and the ring index is projected onto the cornea of the subject's eye. Further, the light source 51 of the projection optical system 50 also serves as an anterior segment illumination that illuminates the anterior segment from an oblique direction.

  The anterior segment front imaging optical system 30 includes an objective lens 32, an imaging lens 37, a filter 34, and a two-dimensional imaging element 35. The filter 34 has an optical characteristic of transmitting light from the light source 40 and cutting light from the light source 91.

  Regarding the projection optical system 40, the light of the fixation target 46 illuminated by the fixation light source (visible light source) 45 passes through the dichroic mirror 97, passes through the projection lens 47, and is then reflected by the dichroic mirror 33. Then, the light travels toward the subject's eye E through the objective lens 32 and the optical filter 200. The examiner performs the measurement while fixing the fixation target 46 to the subject's eye. The optical members from the fixation light source 45 to the objective lens 32 described above form the fixation target projection optical system 40.

  The control unit 70 controls the entire apparatus and calculates measurement results. The control unit 70 is connected to the light source 91, the light source 45, the light source 51, the image sensor 35, the image sensor 99, the monitor 71, the motor 100, and the like. Here, the imaging signal output from the imaging element 35 is subjected to image processing by the control unit 70 and displayed on the monitor 71. Further, the control unit 70 detects the alignment state with respect to the subject's eye based on the imaging signal output from the imaging device 35.

  FIG. 3 is a schematic configuration diagram for explaining the configuration of the optical filter 200, FIG. 3 (a) is a front view, and FIG. 3 (b) is a side view. The optical filter 200 has a single substrate 201 (for example, a glass substrate) having optical characteristics that transmits visible light and infrared light, and is disposed on the subject side of the objective lens 32. The substrate 201 has a slit 202 (a white portion) that transmits light from the light source 91 toward the subject's eye, and other necessary light (for example, front light) that does not transmit light from the light source 91. And a filter portion 203 provided with a coating 203a (hatched portion) having a characteristic of transmitting eye observation light, alignment light, fixation light flux, and the like).

  The operation of the apparatus having the above configuration will be described. When alignment with the measurement optical axis L1 for the subject's eye using the anterior segment front imaging optical system 30 is performed and a trigger signal for performing anterior segment cross-section imaging is generated, the light source 91 is turned on. The light emitted from the light source 91 passes through the condenser lens 93 and is reflected by the scanning mirror 94 provided with the moving mechanism 95. The light reflected by the scanning mirror 94 passes through the slit plate 96 and becomes slit light. The slit light is reflected by the dichroic mirror 97, converted into a substantially parallel light beam by the lens 47, reflected by the dichroic mirror 33, converged by the objective lens 32, and then passed through the slit portion 202 of the optical filter 200. Focused on top.

  Here, when the control unit 70 controls the driving of the motor 100 and moves the scanning mirror 94 in the optical axis direction, the center of the LED light (mainly in the longitudinal direction of the slit plate 96) depending on the position of the scanning mirror 94. Light beam) moves (see FIG. 1). Utilizing this, the scanning mirror 94 is reciprocated at high speed, so that irradiation at the center position where the brightness of the slit light is highest in the entire longitudinal direction of the slit plate 96 becomes possible. In addition, the center position of the brightness of the slit light is scanned on the anterior eye portion and continuously changes by the scanning of the slit light as described above, and thus, for example, when a plurality of LED light sources are arranged, Spot light unevenness is eliminated, and uniform slit light can be obtained.

  The slit cross-sectional image formed on the anterior eye part is imaged by the image sensor 99 via the filter 92 and the lens 98. Note that the scanning speed of the scanning mirror needs to be set so that at least one scan can be performed before the image pickup device 99 acquires an image of one frame. In this case, the control unit 70 may perform one optical scanning (preferably, reciprocating scanning) at a rate faster than at least the frame rate of the image sensor 99.

  In order to capture a cross-sectional image of the eye, it is preferable to capture in a short time. The reason is that the subject cannot completely stop the movement of the eyes, so that the image is blurred and a clear photographed image cannot be obtained. Therefore, it is better to finish shooting one frame at 20 mmsec or less. Under this condition, if one reciprocal scan is performed for one frame, it is necessary to perform a reciprocating motion of 3000 reciprocations per minute. To design as a device, there are 5000 reciprocations or more in consideration of the safety factor. It is better. In this case, for example, the configuration shown in FIG. 1 of this embodiment suitable for high-speed movement of the optical member may be used.

  In this embodiment, at least one scan is performed for photographing one frame. However, the present invention is not limited to this. One scan is performed between several frames and several frames are added. One scan may be used.

  And the control part 70 analyzes the cross-sectional image data acquired by the image pick-up element 99, and calculates the eye characteristic (corneal thickness, anterior chamber depth, corneal curvature) of an anterior eye part. Then, the anterior segment cross-sectional image and the measurement result are displayed on the monitor 71.

  Since the configuration as described above requires only one LED, heat generation can be minimized, and a more compact design than a xenon / high pressure lamp is possible. In addition, since uneven brightness can be reduced as compared with a light source using a plurality of LEDs, uniform illumination light can be obtained.

  In the above-described configuration, the collimator lens is used as the condenser lens 93 so that the slit plate 96 is irradiated with a parallel light beam. For this reason, it is possible to avoid luminance unevenness due to a change in the condensing position with respect to the slit plate 96 due to the movement of the scan mirror 94.

  In the above configuration, a lens system that irradiates the slit plate 96 with a convergent light beam may be used. For example, a cylinder lens that converges a light beam in a direction perpendicular to the longitudinal direction of the slit may be provided between the condenser lens 93 and the light source 91. In this case, it is preferable that the focal length of the cylinder lens is long. This is because the distance between the cylinder lens and the slit 96 changes due to the movement of the scan mirror 94, and if the focal distance is short, there is a possibility that the luminance unevenness due to the change of the condensing position in the optical axis direction may be large. .

  In the above description, the scan mirror 94 is used as a reflection member that can move in the optical axis direction L2. However, the present invention is not limited to this, and other reflection members such as a prism may be used.

In the above description, the scanning mirror 94 is provided with the moving mechanism 95, and only the scanning mirror 94 is moved to move the measurement light. However, the present invention is not limited to this. The condensing lens 93 and the scanning mirror 94 may be integrally reciprocated.

  In addition, a mechanism that can arbitrarily adjust the angle of reflection of the illumination light by using a mechanism that can arbitrarily adjust the angle of the scanning mirror 94 may be used. In this case, in order to efficiently use the illumination light from the light source 91, as shown in FIG. 4, a lens 110 is installed between the slit plate 96 and the scanning mirror 94, and each scanning light incident on the slit plate 96. The principal rays may be parallel to each other. Further, the condensing lens 93 having a long focal length may be used without providing the lens 110, and the distance between the mirror 94 and the slit 96 may be increased.

  In the above configuration, the optical scanning unit is provided between the light source 91 and the slit plate 96. However, it may be in the optical path of the projection optical system 90a, and is disposed between the slit plate 96 and the eye to be examined. It may be a configuration. In this case, since the slit image is moved on the anterior segment, it is better that the scanning speed is high.

  Further, in the above configuration, the light scanning unit is used as the light reflecting member and the driving unit that linearly moves or rotates the light reflecting member. However, the present invention is not limited thereto. For example, an acousto-optic light deflection element (AOD) that performs optical scanning by deflecting illumination light from the light source 91 may be used. Of course, the illumination light may be scanned by a configuration in which only the LED light source 91 is moved at high speed in the longitudinal direction of the slit.

It is a schematic block diagram shown about the optical system of an ophthalmologic apparatus. It is a schematic block diagram shown about the moving mechanism provided with the reflection member. It is a schematic block diagram explaining the structure of an optical filter. It is the schematic which showed the angle change of the reflection member by a moving mechanism.

90a Projection optical system 90b Imaging optical system 91 Light source 94 Scan mirror 95 Moving mechanism 96 Slit plate 99 Image sensor

Claims (5)

An illumination light source and a mask having a slit opening are provided, and includes a projection optical system that projects slit light toward the anterior ocular segment to be examined, and observes or shoots an anterior segment cross-sectional image of the slit light In ophthalmic equipment,
The ophthalmologic apparatus, wherein the projection optical system includes an optical scanning unit that scans light emitted from the illumination light source in a longitudinal direction of the slit. The ophthalmic device according to claim 1.
An imaging optical system having an imaging element that captures a cross-sectional image of the anterior segment by the slit light;
The ophthalmologic apparatus, wherein the optical scanning unit performs at least one optical scan at a rate faster than a frame rate of the image sensor. The ophthalmic apparatus according to claim 2.
The ophthalmologic apparatus, wherein the light scanning unit is disposed between the illumination light source and the slit. The ophthalmic device according to claim 3.
The ophthalmologic apparatus, wherein the illumination light source is one visible light emitting diode. The ophthalmic device according to claim 4.
The optical scanning unit includes a light reflecting member, a motor, and a piston / crank mechanism connected to the light reflecting member and converting a rotational motion of the motor into a linear motion of the light reflecting member. Ophthalmic equipment.

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