WO2018088338A1

WO2018088338A1 - Scanning fundus photography device

Info

Publication number: WO2018088338A1
Application number: PCT/JP2017/039864
Authority: WO
Inventors: 鈴木　孝佳; 雄輝荒井
Original assignee: 興和株式会社
Priority date: 2016-11-08
Filing date: 2017-11-06
Publication date: 2018-05-17
Also published as: JPWO2018088338A1; JP7027326B2

Abstract

Provided is a scanning fundus photography device, which scans and projects slit light upon a fundus 6b of a subject eye 6, receives reflected light from the fundus 6b, and photographs the fundus 6b. This scanning fundus photography device comprises: an illumination optical system which irradiates an optical path segmenting device 2 with the slit light; an objective optical system, further comprising a first scan device 4 which scans the slit light in one direction, a first concave mirror 3 which propagates to the first scan device 4 the slit light which has entered thereupon through the optical path segmenting device 2, and a second concave mirror 5 which propagates to the fundus 6b the slit light which has been scanned with the first scan device 4; and a photographic optical system 7 which receives the reflected light from the fundus 6b which has entered via the optical path segmenting device 2. The first concave mirror 3 enlarges the fan angle of the slit light and relays same to the first scan device 4.

Description

Scanning fundus imaging device

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

Scanning fundus imaging apparatuses called SLO (Scanning Laser Ophthalmoscope) and L-SLO (Line-Scanning Laser Ophthalmoscope) are known as fundus imaging apparatuses for obtaining a fundus image having a high contrast and a wide angle.

For example, in Patent Document 1, laser light emitted from a laser light source is scanned at a high speed in one direction by a first scanning element 14 (polyhedral mirror), and the second scanning element is passed through a scanning compensation means 18 (slit mirror). 16 (vibration plane mirror), and the second scanning element scans the laser beam at a low speed in a direction perpendicular to the scanning direction of the first scanning element 14, thereby scanning the laser beam two-dimensionally. A configuration is disclosed in which the laser beam is reflected by the scanning movement means 20 (primary mirror) and projected onto the fundus.

Further, for example, in Patent Document 2, slit light irradiated using an LED light source 101 and a slit 102 is scanned by a scanning device 105 (galvanomirror), and passes through two optical lenses (a scanning lens 106 and an eyepiece lens 107). A configuration for projecting light onto the fundus is disclosed.

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

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

In addition, the method described in Patent Document 2 adopts an optical system using a lens and requires only one scanning device, so that it is an inexpensive configuration. It is technically difficult to take a wide-angle fundus image of 80 degrees or more. If an optical system using a lens is used to achieve wide-angle shooting with an angle of view of 80 degrees or more, the working length becomes short, the distance between the eye and the lens is narrow, and the operability is poor, and the eye or face of the subject. There is a possibility that a part of the device may come into contact. Further, if a working length with a margin is to be secured, there is a problem that the wide-angle lens has to be enlarged and the apparatus becomes expensive.

The present invention has been made in view of the above points, and provides a scanning fundus photographing apparatus capable of photographing a wide retinal range with high image quality with a configuration that is less expensive than a conventional apparatus. Objective.

In order to achieve the above object, the present invention is a line-scanning fundus imaging apparatus that scans slit light, projects light onto the fundus of the eye to be examined, receives reflected light from the fundus, and images the fundus. An illumination optical system that irradiates the slit light to the optical path dividing device, a first scanning device that scans the slit light in one direction, and the first scanning of the slit light that has entered through the optical path dividing device. An objective optical system having a first concave mirror that transmits to the device, and a second concave mirror that transmits the slit light scanned by the first scanning device to the fundus, and the light that has entered through the optical path splitting device A line-scanning fundus imaging apparatus comprising: an imaging optical system that receives reflected light from the fundus, wherein the first concave mirror increases the spread angle of the slit light (Invention 1). .

According to the above invention (Invention 1), it becomes possible to design a line scanning type fundus imaging apparatus 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. In other words, the objective optical system (the first concave mirror and the second concave mirror) is configured with a dedicated concave mirror to handle wide-angle slit light, but the illumination optical system and the photographing optical system are limited to narrow-angle slit light. In addition, since an expensive optical device such as a large lens is not required, a wide retinal range can be photographed with high image quality with a configuration that is cheaper than the conventional apparatus.

In the above invention (Invention 1), the photographing optical system includes a line-shaped multi-light sensor that receives reflected light from the fundus, and the line-shaped multi-light sensor is synchronized with the first scanning device. You may make it operate | move (invention 2).

Moreover, in the said invention (invention 1), the said imaging | photography optical system rescans the reflected light from the said fundus, and receives the reflected light from the said fundus, and the said two-dimensional multi-optical sensor A second scanning device that is incident on the first scanning device, and the second scanning device performs 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). Furthermore, in the said invention (invention 4), the said 2nd scanning device is good also as what scans the said reflected light in multiple times, while the said 1st scanning device scans the said slit light once (invention 5). By dividing a wide retinal range spatially and photographing multiple times with a multi-light sensor, fundus photographing with a wide angle and high resolution becomes possible.

In the above inventions (Inventions 1 to 5), the optical path dividing device is disposed at the first focal point of the first concave mirror, the first scanning device is disposed at the second focal point, and the first focal point of the second concave mirror is 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 that the second focal point of the second concave mirror is located at the pupil position of the eye to be examined (invention 6). The smaller the patient's pupil diameter, the more difficult the fundus photographing at a wide angle is. However, 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 disposed at a pupil conjugate position of the eye to be examined (Invention 7).

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

According to the line scanning fundus photographing apparatus of the present invention, it is possible to photograph a wide retinal range with high image quality with a configuration that is less expensive than the conventional apparatus.

It is explanatory drawing which shows the optical structure of the line scanning type fundus imaging apparatus which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the optical structure of the objective optical system of the line scanning type fundus imaging apparatus which concerns on the 1st Embodiment in the state seen from the incident direction of slit light. It is explanatory drawing which shows the optical structure of the light-receiving part (shooting optical system) of the line scanning type fundus imaging apparatus according to the first embodiment. It is explanatory drawing which shows typically the structure and light beam path of the objective optical system of the line scanning type fundus imaging apparatus according to the first embodiment. It is explanatory drawing which shows the optical structure of the light-receiving part (imaging optical system) of the line scanning type fundus imaging apparatus which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows typically the light beam path of the reflected light in the line scanning type fundus imaging apparatus according to the second embodiment.

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

As shown in FIGS. 1 and 2, in the line-scanning fundus imaging apparatus according to the present embodiment, slit light from the slit light source 1 (illumination optical system) enters the beam splitter 2 (optical path splitting device), and the beam splitter 2 Is reflected by the first concave mirror 3 and enters the first scanning device 4. The slit light that is simultaneously reflected and scanned 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 examined, and is condensed 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 galvanometer 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 the 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 opposite direction of the arrow along the same optical path, and passes through the second concave mirror 5, the first scanning device 4, and the first concave mirror 3. Then, it is reflected by the beam splitter 2 and enters the light receiving unit 7 (imaging optical system). Since the fundus is illuminated with slit-shaped light, the fundus image formed on the light receiving unit 7 is also slit-shaped. When slit light is scanned by the first scanning device, the fundus portion corresponding to the scanning angle is illuminated in a slit shape, and slit-shaped fundus images are sequentially formed on the light receiving unit 7.

FIG. 3 shows an optical configuration of the light receiving unit 7 of the scanning fundus photographing apparatus according to the present embodiment. The reflected light from the fundus 6b that has entered the light receiving unit 7 is guided to the slit opening 7b by the first relay lens 7a, and the reflected light that has passed through the slit opening 7b passes through the second relay lens 7c, and is photoed by the camera lens 7e. The light enters the photoelectric conversion device 7f (light receiving means) formed 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. Thus, the luminance information of each point of the fundus 6b can be obtained by the photoelectric conversion device 7f. 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, a photographed image of the fundus oculi 6b can be formed. 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 this embodiment collimates light from, for example, a white LED light source, cuts it out at the slit opening, and irradiates the beam splitter 2 as slit light having a predetermined length in the horizontal direction. Configured to be.

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

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

As shown in FIG. 4, the beam splitter 2 is positioned at the first focal point 3 a of the first concave mirror 3, and the galvanometer mirror as the first scanning device 4 is disposed at the second focal point 3 b of the first concave mirror 3. In addition, a 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 to be examined is located at the second focal point 5b of the second concave mirror 5, so that the first 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.

By adopting such an objective optical system configuration, the slit light, which is a light beam with a narrow angle (for example, 50 degrees), can be converted into a wide angle (for example, 150 degrees) slit light by multiplying the magnification by the first concave mirror 3. . This eliminates the need to handle wide-angle slit light in the illumination optical system (slit light source 1) and photographing optical system (light-receiving unit 7), so that a lens having a large and complicated configuration for dealing with wide-angle slit light becomes unnecessary. With a configuration that is cheaper than the apparatus, it is possible to capture a wide retinal range with high image quality.

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

As shown in FIG. 3, the reflected light incident on the light receiving unit 7 is condensed by the first relay lens 7a on the slit opening 7b located on the fundus conjugate surface, passes through the slit opening 7b, and passes through the second relay lens 7c. As a result, a slit-like fundus image is formed on the photoelectric conversion device 7f, which is a line-shaped multi-optical sensor, by the camera lens 7e. The fundus is scanned and photographed by the photoelectric conversion device 7 f 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 a fundus image in a wide two-dimensional range can be obtained.

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

(Second Embodiment)
Next, a second embodiment of the present invention will be described in detail based on the drawings. The line-scanning fundus imaging apparatus according to the second embodiment is obtained by replacing the light-receiving unit 7 of the line-scanning fundus imaging apparatus according to the first embodiment with a light-receiving unit 7A having a different optical configuration. FIG. 5 illustrates an 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 is 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 to the slit opening 7Ab, and the reflected light that has passed through the slit opening 7Ab passes through the second relay lens 7Ac. Then, the light enters the second scanning device 7Ad. The second scanning device 7Ad is configured by a galvanometer mirror, and the reflected light that has passed 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 7Ad. 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 to face each other. Further, the beam splitter 2 is disposed at the front focal position of the first relay lens 7Aa, and the slit opening 7Ab is disposed at the rear focal position. Similarly, the slit opening 7Ab is disposed at the front focal position of the second relay lens 7Ac, and the second scanning device 7Ad (galvano mirror) is disposed at the rear focal position. The reflected light scanned by the second scanning device 7Ad is incident on the photoelectric conversion device 7Af formed of a 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 unit 7A, the slit opening 7Ab is disposed at a position conjugate with the fundus 6b of the eye 6 to be examined. By guiding the reflected light to the slit opening 7Ab arranged in this way, light (stray light) generated around the fundus image is removed by the slit opening 7Ab, and a fundus image with high contrast can be photographed. it can.

In the light receiving unit 7A, the second scanning device 7Ad is disposed at a position conjugate with the pupil 6a of the eye 6 to be examined. The scanning operation of the second scanning device 7Ad is synchronized with the scanning operation of the first scanning device 4. In this way, luminance information of each point on the fundus 6b can be obtained by the photoelectric conversion device 7Af. 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, a photographed image of the fundus oculi 6b can be formed. 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, an area-shaped multi-photosensor (photoelectric conversion device 7Af used in the second embodiment) ) Is generally widespread and has many high-resolution and inexpensive devices, but requires the second scanning device 7Ad. In that respect, the first embodiment has a feature that the configuration is simple because the second scanning device 7Ad is unnecessary. On the other hand, the line-shaped multi-light sensor has a smaller degree of freedom of selection than the area-shaped multi-light sensor. Therefore, neither the first embodiment nor the second embodiment is superior, and each has advantages and disadvantages. Therefore, which light receiving unit configuration should be selected according to the surrounding circumstances.

Here, the synchronization of the scanning operation does not necessarily mean that the scanning is performed at the same scanning speed and the same scanning angle. For example, the second scanning device 7Ad is greater than the scanning angle of the galvanometer mirror that is the first scanning device 4. The second scanning device 7Ad performs three scanning operations while the first scanning device 4 performs one scanning operation, for example, by reducing the scanning angle of the galvanometer mirror, and the second scanning device 4 This means that the scanning operation by the scanning device 7Ad is performed at a timing maintaining a certain relationship.

In the objective optical system, the first scanning device 4 plays a role of illuminating incident slit light at a target position. On the other hand, as shown in FIG. 6, the first scanning device 4 performs rescanning on the reflected light from the fundus 6 b of the eye 6 to be examined. By 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 light advances to the first concave mirror 3. Further, the path of the reflected light is reflected by the first concave mirror 3 and passes through the optical path splitting device (beam splitter 2) to the light receiving unit 7A as a light beam having no scanning position information. Therefore, the second scanning device 7Ad is configured to scan the reflected light again in the light receiving unit 7A, and the second scanning device 7Ad performs the scanning operation in synchronization with the scanning operation of the first scanning device 4. It becomes possible to give the reflected light again scanning position information relating to the position scanned by the one scanning device 4 in the vertical direction. As a result, the reflected light is projected onto the area-shaped multi-light sensor 7Af and formed as a scanned two-dimensional wide-angle fundus image.

Further, the scanning angle of the second scanning device 7Ad (the swing angle of the galvano mirror) is made smaller than the scanning angle of the first scanning device 4 (the swing angle of the galvano mirror), and the first scanning device 4 emits the slit light once. During the scanning, the second scanning device 7Ad scans the reflected light a plurality of times to form a captured image of the fundus 6b, thereby narrowing the imaging range per image and capturing a high-resolution fundus image. be able to.

For example, while the slit light is scanned once by the first scanning device 4, the reflected light is scanned three times by the second scanning device 7Ad, and the camera lens 7Ae and the photoelectric conversion device 7Af are synchronized with the scanning of the second scanning device 7Ad. If the shutter is released three times with a CCD camera configured as follows, three fundus images obtained by dividing the desired imaging target area of the fundus 6b into three can be taken. 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.

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

For example, the beam splitter 2 which is an optical path dividing device may be changed to a perforated mirror or the like. When a perforated mirror is used as an optical path dividing device, slit light is incident from a hole portion of the perforated mirror, and reflected light from the fundus is guided to the photographing optical system using a ring-shaped mirror surface. Thereby, since light projection and light reception can be spatially separated on the surface of the optical path dividing device, there is an effect of removing harmful light generated by the eye or the like with a perforated mirror.

1 Slit light source (illumination optical system)
2 Beam splitter (optical path splitting device)
DESCRIPTION OF SYMBOLS 3 1st concave mirror 4 1st scanning device 5 2nd concave mirror 6 Eye to be examined 6a Pupil 6b Fundus 7, 7A Light-receiving part (imaging optical system)
7a, 7Aa First relay lens 7b, 7Ab Slit aperture 7c, 7Ac Second relay lens 7Ad Second scanning device 7e, 7Ae Camera lens 7f, 7Af Photoelectric conversion device

Claims

A line-scanning fundus imaging device that scans slit light, projects light on the fundus of the subject's eye, receives reflected light from the fundus, and images the fundus,
An illumination optical system for irradiating the slit light to the optical path dividing device;
The first scanning device that scans the slit light in one direction, the first concave mirror that transmits the slit light that has entered through the optical path dividing device to the first scanning device, and the first scanning device. An objective optical system having a second concave mirror that transmits the slit light to the fundus,
An imaging optical system that receives reflected light from the fundus that has entered through the optical path splitting device, and
The line-scanning fundus imaging apparatus, wherein the first concave mirror increases a spread angle of the slit light.
The imaging optical system includes a line-shaped multi-light sensor that receives reflected light from the fundus.
The line-scanning fundus imaging apparatus according to claim 1, wherein the line-shaped multi-optical sensor operates in synchronization with the first scanning device.
The imaging optical system includes a two-dimensional multi-light sensor that receives reflected light from the fundus, and a second scanning device that re-scans the reflected light from the fundus and enters the two-dimensional multi-photo sensor.
The line-scanning fundus imaging apparatus according to claim 1, wherein the second scanning device performs a scanning operation in a direction parallel to each other in synchronization with the scanning operation of the first scanning device.
The line-scanning fundus imaging apparatus according to claim 3, wherein a scanning angle of the second scanning device is smaller than a scanning angle of the first scanning device.
The line-scanning fundus imaging 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 splitting device is disposed at a first focal point of the first concave mirror, and the first scanning device is disposed at a second focal point;
The first focal point of the second concave mirror coincides with the second focal point of the first concave mirror;
6. The line-scanning fundus imaging apparatus according to claim 1, wherein the second focal point of the second concave mirror is located at a pupil position of the eye to be examined.
6. The line-scanning fundus imaging apparatus according to claim 3, wherein the second scanning device is disposed at a pupil conjugate position of the eye to be examined.
The line scanning fundus imaging apparatus according to any one of claims 1 to 7, wherein the imaging optical system has a slit opening at a fundus conjugate position of an eye to be examined.