JPH0357426A - Eyeground inspection device - Google Patents

Abstract

PURPOSE:To eliminate a reflected light at the front eye part under an optimum condition with the luminous flux control means and to always obtain an eyeground image of a high contrast by receiving a reflected light from an eyeground scanned and illuminated with a first and a second optical deflectors, through a selected light shielding element. CONSTITUTION:The reflected light from an eyeground is reflected and led by an objective mirror 17, a mirror 16 and a galvanomirror 15, passes through a luminous flux separating means 12, and thereafter, is condensed onto the light receiving surface of a photodetector 21 such as a photoelectric multiplier by lenses 19, 20. Between the lenses 19, 20, a luminous flux control means 22 for eliminating an unnecessary reflected light by the front eye part of an eye 18 to be examined, and allowing only a reflected light from the eyeground to pass through is arranged. The luminous flux limiting means 22 has black spots of different sizes, etc., and can select arbitrarily one window plate by a turret type structure. Between the lens 20 and the photodetector 21, a detection opening 23 for eliminating an unnecessary scattered light from other part than the eyeground, and enhancing the contrast of an eyeground image is arranged, and also, in front of the photodetector 21, a filter 24 for allowing only a light beam of necessary wavelength to pass through is arranged. By the turret type structure, the filter of an arbitrary characteristic can be selected.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an ophthalmoscopy device, in particular, which uses a laser beam as a light source, deflects and scans the beam two-dimensionally, and irradiates the fundus of the eye to be examined. This article relates to an electronic optometry device that obtains fundus information by receiving, charging, converting, and processing reflected light from the ophthalmoscope, and is particularly concerned with improvements thereto. [Conventional technology 1] Conventionally, in order to examine the fundus of the eye, a method has been widely used in which a doctor directly observes the fundus of a patient using an instrument called an ophthalmoscope, and a method in which the fundus is photographed using a special camera called a fundus camera. It is. In addition, with the recent development of electronic technology, it is now possible to directly extract fundus information as an electrical signal using a photoelectric conversion element such as an image pickup tube instead of the photographic film of a conventional fundus camera, process and store it, or display it on a TV monitor. It is also being displayed on the screen. Under such circumstances, electronic optometry devices using laser scanning that were first developed in the United States (US Pat. No. 4,213,678 and Applied Optics
) Vol. l9 (+980) p. 2991
-) has many characteristics and is attracting attention. That is, C R T (Cathod
The light source 4 in the flying spot scanning type fundus imaging device (e-Ray Tube) was replaced with a laser, and the incident light was limited to a small area in the center of the pupil, and the reflected light from the fundus was diverted from a wide area around the pupil. By taking it out, photoelectrically converting it, and amplifying it, it is now possible to display a fundus image with a high signal-to-noise ratio in low illumination on a TV monitor in real time, and it is also possible to significantly reduce the amount of fluorescent agent injected intravenously in fluorescence fundus photography. This is what happened. In addition, by modulating the scanning light to be irradiated, the retinal function can be examined while observing the fundus image, in other words, it can be used as a fundus visual field/visual test.In addition, the deep focal depth of the laser beam, the removal of corneal reflection due to polarization, and the monochromaticity. It offers the possibility of becoming an extremely excellent diagnostic device in terms of its use and development into a treatment device FfIi (coagulator). This new type of optometry device has since undergone many additional trials and improvements by research groups in various countries, but the applicant has previously invented and developed a highly advanced, highly advanced optometry device and has filed an application. Japanese Patent Publication No. 64-58237
(see publication). According to this invention, a slit is arranged in front of a light receiving element that detects reflected light from the fundus, and the influence of unnecessary scattered light is eliminated by employing the detection slit and a peripheral optical system. Therefore, it is possible to obtain a fundus image with high contrast and a high signal-to-noise ratio using low-intensity illumination, and to realize a fundus examination device using laser scanning that has excellent reliability and operability. [Problems to be Solved by the Invention] However, according to subsequent experimental research by the present applicant, this type of device has problems in the anterior segment of the subject's eye when the subject has opacity, particularly in the cornea or crystalline lens. susceptible to reflected light,
It was found that the contrast of the obtained fundus image may decrease. That is, in this type of device, the incident laser light is limited to a small area at the center of the pupil, and the reflected light from the fundus is blocked at the center at a position conjugate with the pupil.
Only light from the area around the pupil is detected. Therefore, in the case of a subject with a sufficiently transparent anterior segment of the subject's eye, the area that blocks the center of the reflected light flux from the base of the eye may be quite small, but in the case of a subject with anterior segment opacity, etc. In this case, the area must be relatively large. Furthermore, since the light reflected from the anterior segment of the eye is different from the light reflected from the cornea and from the crystalline lens, the light reflected from either of these parts must be sufficiently blocked. If the reflected light from the anterior segment of the eye is insufficiently blocked, the unnecessary reflected light will mix into the detected light, reducing the contrast of the fundus image. Furthermore, the light-shielding area necessary to perform this light-shielding must be determined in consideration of the mydriatic state of the pupil of the eye to be examined, and the area must be set to the minimum value in order to avoid reducing the amount of detected light and lowering the S/N ratio. It is desirable that the size be the same.
In the optical system of the device disclosed in Japanese Patent Application Laid-Open No. 64-58237, light reflected from the pupil is removed by a small mirror placed at a position conjugate with the anterior segment (pupil) of the subject's eye. However, since this mirror plays the role of separating the laser beam irradiated to the fundus of the eye and the detection light reflected from the fundus, there are severe restrictions on the optical system, and it is said that this mirror can be used selectively and flexibly depending on the characteristics of the anterior segment of the eye being examined. 6 On the other hand, in the device disclosed in Japanese Patent Application Laid-open No. 64-58237, the laser beam was ultimately irradiated onto the subject's eye using an objective lens, but since it was a lens, it was necessary to The reflected light from the sensor will mix into the detected light, reducing the contrast of the image. For this reason, the influence of the reflected light was removed by using sunspots, but this type of sunspots also block part of the signal light from the fundus that should be detected, resulting in a decrease in the amount of detected light and a decrease in the S/N ratio. In addition, the positioning adjustment is also difficult.

The purpose of the present invention has been made to solve the above-mentioned problems, so that it is possible to optimally adjust the removal of the anterior segment reflected light according to the conditions of the subject, there is little loss in the amount of detected light, and the cornea and crystalline lens are Our objective is to realize a new practical ophthalmoscopy device using laser scanning that can obtain high-contrast fundus images even in patients with opacity. [A Thousand Steps to Solve the Problems] In order to solve these problems, the present invention aims to two-dimensionally scan laser light from a laser light source, irradiate the fundus of the eye to be examined, and detect the reflection from the fundus. A fundus examination apparatus that obtains fundus information by receiving light with a light-receiving element and photoelectrically converting it, includes a laser light source that generates laser light of a single or multiple wavelengths, and scans the laser light in one direction at a predetermined frequency. a first optical deflector for scanning the laser beam at a frequency lower than the frequency in a direction perpendicular to the scanning direction of the first optical deflector; A light flux limiting means is provided which is located at a position optically substantially conjugate with the anterior segment of the eye and is composed of a plurality of selectable light shielding elements each having a different light shielding property, and is scanned by the first and second optical deflectors. A configuration was adopted in which the reflected light from the illuminated fundus of the eye was received through the selected light shielding element. Furthermore, in the present invention, the fundus of the eye is scanned two-dimensionally with laser light from a laser light source, and the fundus of the eye to be examined is irradiated, and the reflected light from the fundus is received by a light receiving element and photoelectrically converted, thereby obtaining fundus information. The inspection device includes: a laser light source that generates laser light of a single wavelength or a plurality of wavelengths; a first optical deflector that scans the laser light in one direction at a predetermined frequency; a second optical deflector for scanning at a frequency lower than the frequency in a direction perpendicular to the scanning direction of the optical deflector; and a two-dimensional scanning light generated by the optical deflector to the fundus of the eye to be examined. an objective mirror for irradiation; a light flux limiting means having a plurality of selectable light-shielding elements each having a different light-shielding property and located at a position optically conjugate or nearly conjugate with the anterior segment of the eye to be examined; and a fundus of the eye to be examined. We also adopted a configuration with a detection aperture located at an almost optically conjugate position. In addition, a fundus examination device that scans the laser light from a laser light source two-dimensionally and irradiates the fundus of the eye to be examined, and obtains bright fundus information by receiving the reflected light from the fundus with a light receiving element and photoelectrically converting it. a laser light source that generates laser light of a single wavelength or a plurality of wavelengths; a first optical deflector for scanning the laser light in one direction at a predetermined frequency; a second optical deflector for scanning at a frequency lower than the frequency in a direction perpendicular to the scanning direction of the instrument; and a second optical deflector for separating light irradiated onto the fundus of the eye to be examined and light reflected from the fundus from each other. Do they each have different separation characteristics? A configuration including a beam separation means consisting of a selectable beam separation element with a number of 3 f, and a plurality of selectable optical filters each having a different band characteristic and arranged in front of a light receiving element that receives reflected light from the fundus of the eye. is also adopted. [
Effect] According to the above configuration, the reflected light at the anterior segment of the eye can be eliminated under optimal conditions by the light flux limiting means according to the characteristics of the subject's eye, so a fundus image with high contrast can always be obtained. It also has high operability, as the beam separation means and filter can be easily selected and set depending on the imaging purpose. Furthermore, by using an objective mirror, there is no need for a black dot to remove surface reflections, as is the case with objective lenses, and the efficiency of the optical system is high, resulting in high image quality with SNi5 and good contrast, including the effect of the detection aperture. It is possible to realize the following imaging functions. [Example] Hereinafter, the present invention will be explained in detail based on the example shown in FIGS. 1 to 5. FIG. 1 shows the overall schematic configuration of the optical system of the bottom inspection device according to the present invention. In FIG.
- Ne) or a laser light source such as a semiconductor. A laser beam 2 from a laser light source is expanded to a predetermined size by a beam expander 3, then reflected by a mirror 4, and enters a lens 5. The lens 5 has an acousto-optic deflection element (acousto-optic deflection element) following it.
A reflector (hereinafter referred to as AOD) 6 is used to shape and input a laser beam into a rectangular aperture, and includes a combination of multiple cylindrical lenses. Prisms 7 and 8 are placed before and after the AOD 6 in order to correct the light wavelength dependence of the incident angle and output angle of the AOD with respect to the laser beam. However, this prism is not necessarily necessary when using only a monochromatic laser beam. The AOD operates according to signal source 6″;
For example, 15.75k, which corresponds to the horizontal scanning of a normal TV.
} Deflect and scan the laser beam at a frequency of lz. AOD
The laser beam that has been deflected in a one-dimensional direction (horizontal direction) is shaped by a lens 9 having a configuration similar to that of the lens 5 from a rectangular beam suitable for the aperture of the AOD to an original circular beam. The scanning light emitted from lens 9 is transmitted to lens 10.
, 11, part of it is reflected by the subsequent thousand light beam separation stages l2, and part of it passes through. As will be explained later, the ten-stage beam splitter l2 is composed of a flat plate type non-polarizing beam splitter, a polarizing beam splitter, a dichroic mirror, etc., and any one of them can be selected as necessary using a turret type structure. It has become.

The laser light that has passed through the thousand beam separation stages l2 enters a light receiving element l3 such as a photodiode, and its output signal is used to monitor the amount of laser light. On the other hand, the laser beam reflected by the beam separation means l2 is transmitted to the galvanometer 14.
guided by a mirror (galvano mirror) 15 attached to the Galvanometer mirror l5 operates according to signal source 14'';
For example, a laser beam is deflected and scanned at a frequency of 60Hz, which corresponds to the vertical scanning of a television, and the scanning direction is A.
It is perpendicular to the scanning direction by OD6. Therefore, a two-dimensional laser raster corresponding to the television scanning line is formed, which is reflected by the mirror I6 and the objective mirror I7, and is projected onto the fundus through the center of the pupil of the eye 18 to be examined. The reflected light from the fundus, indicated by the dotted line in FIG. 1, returns to the objective mirror 17. It is reflected by a mirror 16 and a galvanometer mirror 15 and guided, and after passing through a thousand light beam separation stages 12, a lens 19
．． 20, the electrons are collected on the light receiving surface of a light receiving element 2l such as a photomultiplier tube. In such an optical system using the objective mirror 17, the present applicant previously proposed Japanese Patent Application Laid-open No. 64-58.
Unlike the optical system shown in Japanese Patent No. 237, there is no need for a black dot to eliminate surface reflection of the objective lens, and there is no problem with light quantity loss or positioning due to a black dot.

Between the lenses 19 and 20, a luminous flux limiting stage 22 is arranged to remove unnecessary reflected light from the anterior segment of the eye 18 to be examined and to allow only reflected light from the fundus to pass through. Luminous flux limiting means 22
As will be explained later, it is composed of multiple transparent window plates with sunspots etc. of different sizes, and one window plate can be arbitrarily selected from among the plurality using a turret-type structure similar to the 1,000-stage luminous flux separation l2. It looks like this. A detection aperture (slit) 23 is arranged between the lens 20 and the light receiving element 21 to eliminate unnecessary scattered light from sources other than the fundus and to increase the contrast of the fundus image. A filter 24 is arranged to allow only light to pass through. The filter 24 has a turret structure similar to the light beam separation stage 12i5 and the optical limiter 22,
Filters with arbitrary characteristics can be selected.
Furthermore, as is clear from Fig. 1, the galvanometer mirror 15
The light flux limiting means 2215 and the light receiving element l3 are connected to the eye to be examined l8.
It is placed at a position that is optically conjugate with the pupil of the eye. Further, the light receiving surface of the light receiving element 2l is located at a position optically conjugate with the pupil of the eye to be examined.
Or be placed nearby. FIG. 2 is a configuration diagram that reproduces the optical system shown in FIG. 1 already explained, especially the light receiving system, in a form closer to the actual arrangement than in FIG. 1. In Figure 2, AOD (second
The laser beam is deflected in a one-dimensional (horizontal) direction by a beam splitter (not shown), enters the lens 11, is reflected by a thousand beam separation stages l2, and is guided to a galvanometer mirror l5. The galvano mirror 15 deflects the laser beam in a direction (vertical direction) perpendicular to the scanning direction by the AOD, and a two-dimensional laser raster is generated. In Figure 2, the scanning direction by the AOD (
The term "horizontal direction" means perpendicular to the paper surface of FIG. 2, while the scanning direction (vertical direction) by the galvanometer mirror 15 means horizontal to the paper surface of FIG. Galvano mirror 15
The laser beam reflected by the fundus is guided by mirror l6 and objective mirror 17 and irradiated onto the fundus of the eye to be examined l8, and the reflected light from the fundus (indicated by dotted lines in FIG. 2) is guided by mirror l6 and objective mirror 17. , returns through 15. The reflected light from the fundus after passing through the thousand light beam separation stages l2 and being separated from the incident light passes through the lens 19, the light beam limiting means 22, the lens 20, the slit 23, and the filter 24, and is guided to the light receiving element 2l. An image signal is obtained through photoelectric conversion. In Fig. 2, the reflected light from the fundus of the eye, indicated by the dotted line from the galvanometer mirror 15 to the light receiving element 2l, is scanned only in the horizontal direction, so the light flux is aligned along the central axis of the optical system, as if It is depicted as unscanned. As is clear from this figure, the slit 23
is arranged at a position optically conjugate with the fundus of the eye 18 to be examined, and plays the role of specifically removing unnecessary scattered light from the ocular optical system. As already mentioned, luminous flux separation means! 2. Both the light flux limiting means 22 and the filter 24 have a turret-type structure having a plurality of optical components with different characteristics, and each of the light flux limiting means 22 and the filter 24 has a turret-type structure having a plurality of optical components having different characteristics.
It rotates around ′, making it easy to select optical components with optimal characteristics as needed. Figure 3 specifically shows the configuration of the 1,000-stage beam separation l2. In Fig. 3, three types of optical components are shown, and the google clock mirror 12a is used, for example, when performing fluorescence fundus photography using Ar laser light with a wavelength of 488 nm as a light source. be. This dichroic mirror preferably has characteristics such that it reflects 99% or more of light with a wavelength of about 500 nm or less, and transmits 90% or more of light with a wavelength longer than that. The second polarization beam splitter 12b is, for example, a 514.
It has the characteristic of reflecting the S-polarized component and transmitting the P-polarized component of light with a wavelength of 5 nm, and is used when imaging the fundus in a monochromatic manner, especially taking into account the polarization characteristics. The third non-polarizing beam splitter 12c has characteristics such that, for example, about 25% of the light is reflected and about 75% of the light is transmitted regardless of the wavelength or polarization component.

Claims (1)

[Scope of Claims] 1) Two-dimensional scanning of laser light from a laser light source is applied to the fundus of the eye to be examined, and the reflected light from the fundus is received by a light-receiving element and photoelectrically converted to obtain fundus information. A fundus examination apparatus comprising: a laser light source that generates laser light of a single wavelength or a plurality of wavelengths; a first optical deflector that scans the laser light in one direction at a predetermined frequency; a second optical deflector for scanning at a frequency lower than the frequency in a direction perpendicular to the scanning direction of the first optical deflector; is provided with a light flux limiting means consisting of a plurality of selectable light shielding elements having different light shielding properties, and the light flux limiting means is configured to pass the reflected light from the fundus scanned and illuminated by the first and second light deflectors to the selected light shielding element. An ophthalmoscopy device characterized by receiving light through the ophthalmoscope. 2) The light flux limiting means is a rotating disc having a plurality of light shielding elements arranged at predetermined intervals around the periphery, and one light shielding element is inserted into the optical path as the disc rotates. The fundus examination device according to item 1. 3) The fundus examination apparatus according to claim 1 or 2, wherein the light shielding element is composed of a transparent window plate having sunspots of different sizes. 4) A light beam separating means is provided for separating the light irradiated onto the fundus of the eye to be examined and the light reflected from the fundus, and the light beam separating means is composed of a plurality of selectable light beam separating elements having different optical characteristics. The fundus examination apparatus according to any one of claims 1 to 3, characterized in that: 5) The fundus examination apparatus according to claim 4, wherein the beam separating means includes a beam separating element such as a dichroic mirror, a polarizing beam splitter, and a non-polarizing beam splitter. 6) A filter means having a plurality of selectable filter elements having different band characteristics is arranged in front of the light receiving element, and the filter element is selected according to the selected beam splitting element. The fundus examination device according to any one of Items 1 to 5. 7) In a fundus examination device that two-dimensionally scans a laser beam from a laser light source and irradiates the fundus of the eye to be examined, and obtains fundus information by receiving and photoelectrically converting the reflected light from the fundus with a light receiving element, a laser light source that generates laser light with a single wavelength or a plurality of wavelengths; a first optical deflector that scans the laser light in one direction at a predetermined frequency; a second optical deflector for scanning at a frequency lower than the frequency in a direction perpendicular to the scanning direction; and a second optical deflector for irradiating the fundus of the subject's eye with the two-dimensional scanning light generated by the optical deflector. an objective mirror; a light flux limiting means having a plurality of selectable light-shielding elements each having a different light-shielding property; A fundus examination device comprising a detection aperture arranged at a conjugate position. 8) In a fundus examination device that two-dimensionally scans laser light from a laser light source and irradiates the fundus of the eye to be examined, and obtains fundus information by receiving reflected light from the fundus with a light receiving element and photoelectrically converting it, a laser light source that generates laser light with a single wavelength or a plurality of wavelengths; a first optical deflector that scans the laser light in one direction at a predetermined frequency; a second optical deflector for scanning at a frequency lower than the frequency in a direction perpendicular to the scanning direction; and a second optical deflector for separating the irradiated light to the fundus of the examined eye and the reflected light from the fundus from each other. A beam separating means consisting of a plurality of selectable beam separating elements having different separation characteristics; and a plurality of selectable optical filters each having a different band characteristic and arranged in front of a light receiving element that receives reflected light from the fundus of the eye. An ophthalmoscopy device characterized by having the following.