JP7027326B2 - Scanning fundus photography device - Google Patents

Description

The present invention relates to a scanning fundus photography apparatus that scans light with respect to the fundus and receives the reflected light from the fundus to photograph the fundus.

Scanning fundus photography devices called SLO (Scanning Laser Ophthalmoscope) and L-SLO (Line-Scanning Laser Ophthalmoscope) are known as fundus photography devices for obtaining wide-angle fundus images with high contrast.

For example, in Patent Document 1, the laser light emitted from the laser light source is scanned at high speed in one direction by the first scanning element 14 (multifaceted mirror), and the second scanning element is scanned via the scanning compensating means 18 (slit mirror). The laser light is scanned two-dimensionally by incident on 16 (vibration plane mirror) and the second scanning element scans the laser light at a low speed in a direction orthogonal to the scanning direction of the first scanning element 14, and the two-dimensional scanning is performed. A configuration is disclosed in which the laser light is reflected by the scanning moving means 20 (primary mirror) and projected onto the fundus of the eye.

Further, for example, in Patent Document 2, the slit light irradiated by the LED light source 101 and the slit 102 is scanned by the scanning device 105 (galvano mirror) and passed through two optical lenses (scanning lens 106 and eyepiece lens 107). A configuration is disclosed in which light is projected onto the fundus of the eye.

Japanese Patent No. 5330236 US Patent Publication 2015/0131050A1

However, in the method described in Patent Document 1, although an image having high contrast can be obtained because it is a point scanning method, on the other hand, a monochromatic image is basically taken because a laser is used as a light source. It becomes. Therefore, in order to realize a color image, it is necessary to mount a plurality of expensive laser light sources, and there is a problem that the device becomes an expensive configuration. Further, the laser light source has a problem that the wavelength width is narrow and the color reproducibility of the captured fundus image is poor.

Further, in the method described in Patent Document 2, an optical system using a lens is adopted, and since only one scanning device is required, the configuration is inexpensive, but on the other hand, the angle of view is configured by the lens. It is technically difficult to capture a wide-angle fundus image of 80 degrees or more. If an optical system using a lens is to be used for wide-angle photography with an angle of view of 80 degrees or more, the working length will be short, and the distance between the eye to be inspected and the lens will be narrow, resulting in poor operability. There is a possibility that a part of the device may come into contact with the lens. In order to secure a working length with a margin, there is no choice but to increase the size of the wide-angle lens, which causes a problem that the device becomes expensive.

The present invention has been made in view of such a point, and it is an object of the present invention to provide a scanning fundus photography apparatus capable of photographing a wide retina range with high image quality with a configuration inexpensiveer than that of a conventional apparatus. The purpose.

In order to achieve the above object, the present invention is a line scanning type fundus imaging device that scans slit light, projects light onto the fundus of the eye to be inspected, receives reflected light from the fundus, and photographs the fundus. The illumination optical system that irradiates the slit light to the optical path dividing device, the first scanning device that scans the slit light in one direction, and the slit light that enters through the optical path dividing device is scanned in the first scan. The objective optical system having a first concave mirror transmitted to the device, a second concave mirror transmitting the slit light scanned by the first scanning device to the fundus, and the light entering through the optical path dividing device. Provided is a line scanning type fundus imaging apparatus comprising a photographing optical system that receives light reflected from the fundus, and the first concave mirror expands the spread angle of the slit light (Invention 1).

According to the above invention (Invention 1), it is possible to design a line scanning fundus photography apparatus by taking advantage of the features of a lens optical system that handles narrow-angle slit light and a concave mirror optical system that handles wide-angle slit light. That is, the objective optical system (first concave mirror and second concave mirror) is composed of a dedicated concave mirror for handling wide-angle slit light, but the illumination optical system and the photographing optical system are limited to narrow-angle slit light. Therefore, since an expensive optical device such as a large lens is not required, it is possible to take a wide retinal range with high image quality with a configuration inexpensiveer than that of a conventional device.

In the above invention (Invention 1), the photographing optical system includes a line-shaped multi-optical sensor that receives the reflected light from the fundus, and the line-shaped multi-optical sensor synchronizes with the first scanning device. It may be made to work (Invention 2).

Further, in the above invention (Invention 1), the photographing optical system rescanns the two-dimensional multi-optical sensor that receives the reflected light from the fundus and the two-dimensional multi-optical sensor that rescans the reflected light from the fundus. A second scanning device may be provided, and the second scanning device may perform a scanning operation in a direction parallel to each other in synchronization with the scanning operation of the first scanning device (Invention 3).

In the above invention (Invention 3), the scanning angle of the second scanning device may be smaller than the scanning angle of the first scanning device (Invention 4). Further, in the above invention (Invention 4), the second scanning device may scan the reflected light a plurality of times while the first scanning device scans the slit light once (Invention 5). By spatially dividing a wide retinal area and taking multiple images with a multi-optical sensor, it is possible to take a wide-angle and high-resolution fundus image.

In the above inventions (Inventions 1 to 5), the optical path dividing device is arranged at the first focal point of the first concave mirror, the first scanning device is arranged at the second focal point, and the first focal point of the second concave mirror is the said. It is preferable that the second focal point of the second concave mirror coincides with the second focal point of the first concave mirror and is located at the pupil position of the eye to be inspected (Invention 6). The smaller the pupil diameter of a patient, the more difficult it is to take a wide-angle fundus photograph, but according to the above invention (Invention 6), this is possible.

In the above inventions (Inventions 3 to 5), it is preferable that the second scanning device is arranged at the pupil conjugate position of the eye to be inspected (Invention 7).

In the above inventions (Inventions 1 to 7), it is preferable that the photographing optical system has a slit opening at the fundus conjugate position of the eye to be inspected (Invention 8). Since the slit openings arranged in this way allow light reflected from the fundus to pass through but do not allow light from other than the fundus to pass through, a high-contrast fundus image can be obtained.

According to the line scanning fundus photography apparatus of the present invention, it is possible to photograph a wide retina range with high image quality with a configuration inexpensiveer than that of the conventional apparatus.

It is explanatory drawing which shows the optical structure of the line scanning type fundus photography apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the optical structure of the objective optical system of the line scanning fundus photography apparatus which concerns on the 1st Embodiment in the state which was seen from the incident direction of the slit light. It is explanatory drawing which shows the optical structure of the light receiving part (photographing optical system) of the line scanning type fundus photography apparatus which concerns on the 1st Embodiment. It is explanatory drawing which shows typically the structure of the objective optical system and the ray optical path of the line scanning fundus photography apparatus which concerns on the 1st Embodiment. It is explanatory drawing which shows the optical structure of the light receiving part (photographing optical system) of the line scanning type fundus photography apparatus which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows typically the light path of the reflected light in the line scanning type fundus photography apparatus which concerns on the 2nd Embodiment.

(First Embodiment)
Hereinafter, the first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a basic optical configuration of the line scanning fundus photography apparatus according to the present embodiment, and FIG. 2 shows an optical configuration of an objective optical system of the line scanning fundus photography apparatus according to the present embodiment. Is shown in the state seen from the incident direction of the slit light (the state seen from the direction of the arrow A in FIG. 1).

As shown in FIGS. 1 and 2, in the line scanning type fundus imaging apparatus according to the present embodiment, the slit light from the slit light source 1 (illumination optical system) is incident on the beam splitter 2 (optical path splitting device), and the beam splitter 2 is used. The slit light transmitted through the above is reflected by the first concave mirror 3 and incident on the first scanning device 4. The slit light scanned at the same time as being reflected by the first scanning device 4 is reflected by the second concave mirror 5, passes through the pupil 6a of the eye 6 to be inspected, and is focused on the fundus 6b. The spreading direction of the slit light is perpendicular to the scanning direction of the first scanning device 4 (for example, a galvano mirror). The spreading direction of the slit light in FIG. 1 is a direction perpendicular to the paper surface, and the spreading direction of the slit light in FIG. 2 is a left-right direction.

The slit light projected on the fundus 6b is reflected by the fundus 6b, and the reflected light from the fundus 6b travels in the same optical path in the direction opposite to the arrow, and the second concave mirror 5, the first scanning device 4, and the first concave mirror 3 are used. After that, it is reflected by the beam splitter 2 and incident on the light receiving unit 7 (photographing optical system). Since the fundus is illuminated with slit-shaped light, the fundus image formed on the light receiving portion 7 also has a slit-like shape. When the slit light is scanned by the first scanning device, the portion of the fundus corresponding to the scanning angle is illuminated in a slit shape, and the slit-shaped fundus image is sequentially imaged on the light receiving portion 7.

FIG. 3 illustrates the optical configuration of the light receiving unit 7 of the scanning fundus photography apparatus according to the present embodiment. The reflected light from the fundus 6b incident on the light receiving portion 7 is guided to the slit opening 7b by the first relay lens 7a, and the reflected light passing through the slit opening 7b passes through the second relay lens 7c and is photographed by the camera lens 7e. It is incident on the photoelectric conversion device 7f (light receiving means) composed of a diode. The photoelectric conversion device 7f is a line-shaped multi-optical sensor, for example, a line camera in which photodiodes are arranged in a one-dimensional line shape. In this way, the luminance information of each point of the fundus 6b can be obtained by the photoelectric conversion device 7f. Then, a photographed image of the fundus 6b can be formed based on the obtained luminance information, that is, the output intensity of the photoelectric conversion device 7f and the scanning position information of the scanning device. The photographed fundus 6b is stored in a storage device (not shown), displayed on a display (not shown), or printed by a printer (not shown).

The slit light source 1 in the present embodiment collimates the light from, for example, a white LED light source, cuts it at the slit opening, and irradiates the beam splitter 2 with the light passing through the slit as slit light having a predetermined length in the horizontal direction. Is configured to be.

The configuration from the beam splitter 2 to the pupil 6a of the eye 6 to be inspected is the objective optical system of the scanning type fundus photographing apparatus according to the present embodiment, and the projection optical path of the slit light emitted from the slit light source 1 and the fundus 6b. It is a common optical path for the light receiving path of the reflected light. FIG. 4 shows a schematic diagram of the optical arrangement of the objective optical system. In FIG. 4, the light rays are shown to be transmitted in one direction so that the flow of the light rays can be easily understood. Therefore, although it is described that the light rays are transmitted by the first concave mirror 3 and the second concave mirror 5, the actual light rays are reflected by each concave mirror. In this objective optical system, the first concave mirror 3 relays the slit light from the beam splitter 2 located at the first pupil position to the first scanning device 4 located at the second pupil position. The spread angle of the slit light is enlarged by the first concave mirror 3. For example, the slit light incident on the first concave mirror 3 is a light beam having a spread angle of 50 degrees (θ1 in the figure), and the slit light reflected by the first concave mirror 3 has a spread angle of 150 degrees (θ2 in the figure). It is enlarged and transmitted to the first scanning device 4. Further, the first concave mirror 3 can be, for example, a slit-shaped elliptical mirror extending in the horizontal direction.

The first scanning device 4 is composed of a galvano mirror, and the wide-angle slit light reflected by the first concave mirror 3 is scanned at a low speed in the vertical direction (direction perpendicular to the longitudinal direction of the slit light) by the first scanning device 4. Is incident on the second concave mirror 5.

The second concave mirror 5 relays the slit light scanned by the first scanning device 4 located at the second pupil position to the pupil 6a of the eye 6 located at the third pupil position, and the scanned slit. The light is reflected by the second concave mirror 5, focused on the pupil 6a of the eye 6 to be inspected, and projected onto the fundus 6b. The second concave mirror 5 can be, for example, a wide-angle elliptical mirror.

As shown in FIG. 4, a beam splitter 2 is located at the first focal point 3a of the first concave mirror 3, and the galvano mirror, which is the first scanning device 4, is arranged at the second focal point 3b of the first concave mirror 3. Further, since the galvano mirror, which is the first scanning device 4, is arranged at the first focal point 5a of the second concave mirror 5, and the pupil 6a of the eye 6 is located at the second focal point 5b of the second concave mirror 5, the first focal point 6a is located. The second focal point 3b of the concave mirror 3 and the first focal point 5a of the second concave mirror 5 are at the same position.

With such an objective optical system configuration, the slit light, which is a light ray having a narrow angle (for example, 50 degrees), can be magnified by the first concave mirror 3 to obtain a slit light having a wide angle (for example, 150 degrees). .. This eliminates the need to handle wide-angle slit light in the illumination optical system (slit light source 1) and the photographing optical system (light receiving unit 7), thus eliminating the need for a lens having a large and complicated configuration for supporting wide-angle slit light. With a configuration that is cheaper than the device, it is possible to shoot a wide range of retina with high image quality.

The slit light projected to the fundus 6b is reflected by the fundus 6b, and the reflected light from the fundus 6b travels in the same light path as the slit light in the opposite direction as shown in FIG. It is reflected by the beam splitter 2 through the device 4 and the first concave mirror 3, and is incident on the light receiving unit 7.

As shown in FIG. 3, the reflected light incident on the light receiving portion 7 is collected by the first relay lens 7a into the slit opening 7b located on the fundus conjugate surface, passes through the slit opening 7b, and passes through the second relay lens 7c. Then, the camera lens 7e forms a slit-shaped fundus image on the photoelectric conversion device 7f, which is a line-shaped multi-optical sensor. The fundus is scanned and photographed by the photoelectric conversion device 7f in synchronization with the scanning of the first scanning device 4. The acquired fundus images are arranged based on the scanning position information of the first scanning device 4, and it is possible to obtain a two-dimensional wide-range fundus image.

In the light receiving portion 7, the slit opening 7b is arranged at a position conjugate with the fundus 6b of the eye 6 to be inspected. By guiding the reflected light to the slit opening 7b arranged in this way, the light (stray light) unnecessary for measurement generated around the fundus image is removed by the slit opening 7b, and a high-contrast fundus image can be taken. can.

(Second embodiment)
Subsequently, a second embodiment of the present invention will be described in detail with reference to the drawings. The line scanning fundus photography apparatus according to the second embodiment replaces the light receiving unit 7 of the line scanning fundus photography apparatus according to the first embodiment with a light receiving unit 7A having a different optical configuration. FIG. 5 illustrates the optical configuration of the light receiving unit 7A according to the present embodiment. Since the configuration other than the light receiving unit 7A is the same as that of the first embodiment, the description thereof will be omitted.

As shown in FIG. 5, the reflected light from the fundus 6b incident on the light receiving portion 7A is collected by the first relay lens 7Aa into the slit opening 7Ab, and the reflected light passing through the slit opening 7Ab passes through the second relay lens 7Ac. Then, it is incident on the second scanning device 7Ad. The second scanning device 7Ad is composed of a galvano mirror, and the reflected light passing through the slit opening 7Ab is scanned at a low speed in the vertical direction (direction perpendicular to the longitudinal direction of the slit light) by the second scanning device 7Ae. Is incident on. The first relay lens 7Aa and the second relay lens 7Ac are spherical lens groups having the same focal length, and are arranged facing each other. Further, a beam splitter 2 is arranged at the front focal position of the first relay lens 7Aa, and a slit opening 7Ab is arranged at the posterior focal position. Similarly, the slit opening 7Ab is arranged at the front focal position of the second relay lens 7Ac, and the second scanning device 7Ad (galvano mirror) is arranged at the posterior focal position. The reflected light scanned by the second scanning device 7Ad is incident on the photoelectric conversion device 7Af configured by the photodiode by the camera lens 7Ae. The photoelectric conversion device 7Af is a two-dimensional multi-optical sensor, for example, a CCD camera in which photodiodes are arranged in a two-dimensional area.

In the light receiving portion 7A, the slit opening 7Ab is arranged at a position conjugate with the fundus 6b of the eye 6 to be inspected. By guiding the reflected light to the slit opening 7Ab arranged in this way, the light (stray light) unnecessary for measurement generated around the fundus image is removed by the slit opening 7Ab, and a high-contrast fundus image can be taken. can.

In the light receiving unit 7A, the second scanning device 7Ad is arranged at a position conjugate with the pupil 6a of the eye 6 to be inspected. Further, the scanning operation of the second scanning device 7Ad is synchronized with the scanning operation of the first scanning device 4. In this way, the luminance information of each point of the fundus 6b can be obtained by the photoelectric conversion device 7Af. Then, a photographed image of the fundus 6b can be formed based on the obtained luminance information, that is, the output intensity of the photoelectric conversion device 7Af and the scanning position information of the two scanning devices. The photographed fundus 6b is stored in a storage device (not shown), displayed on a display (not shown), or printed by a printer (not shown).

Comparing the configuration of the light receiving unit 7 according to the first embodiment with the configuration of the light receiving unit 7A according to the second embodiment, the area-shaped multi-optical sensor (photoelectric conversion device 7Af) used in the second embodiment is compared. ) Is widely used in general, and many of them have high resolution and are inexpensive, but a second scanning device 7Ad is required. In that respect, the first embodiment has a feature that the configuration is simplified because the second scanning device 7Ad is not required. On the other hand, the line-shaped multi-optical sensor has less freedom of selection than the area-shaped multi-optical sensor. Therefore, which of the first embodiment and the second embodiment is not superior, and each has advantages and disadvantages. Therefore, it should be selected which light receiving unit is configured according to the surrounding circumstances.

Here, synchronization of scanning operations does not necessarily mean scanning at the same scanning speed and the same scanning angle, and is, for example, the second scanning device 7Ad rather than the scanning angle of the galvano mirror which is the first scanning device 4. The scanning operation by the first scanning device 4 and the second scanning operation such that the scanning angle of the galvano mirror is reduced and the second scanning device 7Ad performs three scanning operations while the first scanning device 4 performs one scanning operation. This means that the scanning operation by the scanning device 7Ad is performed at a timing that maintains a certain relationship.

In the objective optical system, the first scanning device 4 plays a role of illuminating the incident slit light at a target position. On the other hand, as shown in FIG. 6, the first scanning device 4 rescans the reflected light from the fundus 6b of the eye 6 to be inspected. Due to this rescanning, the reflected light follows the same path as the incident slit light, so that the scanning position information with respect to the fundus is lost and the process proceeds to the first concave mirror 3. Further, the path of the reflected light is reflected by the first concave mirror 3, passes through the optical path splitting device (beam splitter 2), and heads toward the light receiving unit 7A as a light ray having no scanning position information. Therefore, in the light receiving unit 7A, the second scanning device 7Ad is configured to scan the reflected light again, and the second scanning device 7Ad performs the scanning operation in synchronization with the scanning operation of the first scanning device 4. 1 It is possible to give the reflected light the scanning position information regarding the position scanned in the vertical direction by the scanning device 4 again. As a result, the reflected light is projected onto the area-shaped multi-optical sensor 7Af and imaged as a scanned two-dimensional wide-angle fundus image.

Further, the scanning angle of the second scanning device 7Ad (swing angle of the galvano mirror) is made smaller than the scanning angle of the first scanning device 4 (swing angle of the galvano mirror), and the slit light is emitted once by the first scanning device 4. By scanning the reflected light multiple times with the second scanning device 7Ad during scanning to form a photographed image of the fundus 6b, the imaging range per image is narrowed and a high-resolution image of the fundus is captured. be able to.

For example, while the first scanning device 4 scans the slit light once, the second scanning device 7Ad scans the reflected light three times, and the camera lens 7Ae and the photoelectric conversion device 7Af are scanned in accordance with the scanning of the second scanning device 7Ad. If the shutter is released three times with a CCD camera composed of the above, it is possible to take three images of the fundus, which is obtained by dividing the desired imaging target area of the fundus 6b into three. By joining these three fundus images by image processing, it is possible to obtain one high-resolution fundus image that covers the entire imaging target area of the fundus 6b.

Although the scanning ophthalmologic imaging apparatus according to the present invention has been described above with reference to the drawings, the present invention is not limited to the above embodiment, and various modifications can be made.

For example, the beam splitter 2 which is an optical path splitting device may be changed to a perforated mirror or the like. When the perforated mirror is used as an optical path dividing device, slit light enters through the hole of the perforated mirror and the reflected light from the fundus is guided to the photographing optical system by using the ring-shaped mirror surface. As a result, the projected light and the received light can be spatially separated on the surface of the optical path dividing device, so that there is an effect of removing harmful light generated by the eyes or the like by a perforated mirror.

1 Slit light source (illumination optical system)
2 Beam splitter (optical path splitting device)
3 1st concave mirror 4 1st scanning device 5 2nd concave mirror 6 Eye to be inspected 6a Eye 6b Fundus 7, 7A Light receiving part (photographing optical system)
7a, 7Aa 1st relay lens 7b, 7Ab Slit opening 7c, 7Ac 2nd relay lens 7Ad 2nd scanning device 7e, 7Ae Camera lens 7f, 7Af Photoelectric conversion device

Claims (8)

A line-scanning fundus photography device that scans slit light, projects light onto the fundus of the eye to be inspected, receives reflected light from the fundus, and photographs the fundus.
An illumination optical system that irradiates the optical path dividing device with the slit light,
The first scanning device that scans the slit light in one direction, the first concave mirror that transmits the slit light that enters through the optical path dividing device to the first scanning device, and the first scanning device scan the light. An objective optical system having a second concave mirror that transmits the slit light to the fundus, and an objective optical system.
It is provided with a photographing optical system that receives the reflected light from the fundus that has entered through the optical path dividing device.
A line scanning fundus photography apparatus, wherein the first concave mirror expands the spread angle of the slit light. The photographing optical system includes a line-shaped multi-optical sensor that receives the reflected light from the fundus.
The line-scanning fundus photography apparatus according to claim 1, wherein the line-shaped multi-optical sensor operates in synchronization with the first scanning device. The photographing optical system includes a two-dimensional multi-optical sensor that receives the reflected light from the fundus, and a second scanning device that rescans the reflected light from the fundus and causes the reflected light to be incident on the two-dimensional multi-optical sensor.
The line scanning fundus photography apparatus according to claim 1, wherein the second scanning device performs a scanning operation in synchronization with the scanning operation of the first scanning device. The line scanning fundus photography apparatus according to claim 3, wherein the scanning angle of the second scanning device is smaller than the scanning angle of the first scanning device. The line-scanning fundus photography apparatus according to claim 4, wherein the second scanning device scans the reflected light a plurality of times while the first scanning device scans the slit light once. The optical path dividing device is arranged at the first focal point of the first concave mirror, and the first scanning device is arranged at the second focal point.
The first focus of the second concave mirror coincides with the second focus of the first concave mirror.
The line scanning fundus photography apparatus according to any one of claims 1 to 5, wherein the second focal point of the second concave mirror is located at the pupil position of the eye to be inspected. The line scanning fundus photography apparatus according to any one of claims 3 to 5, wherein the second scanning device is arranged at a pupil conjugate position of the eye to be inspected. The line scanning fundus photography apparatus according to any one of claims 1 to 7, wherein the photographing optical system has a slit opening at a fundus conjugate position of the eye to be inspected.

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