JPH08107883A - Fundus camera - Google Patents

Abstract

(57) [Summary] [Purpose] With a simple configuration, astigmatism of the eye to be inspected is corrected to focus the fundus image. [Structure] During alignment and fundus observation, a light flux reflected by a fundus illuminating light source 12 on a fundus Er passes through a photographing diaphragm 4, is reflected by a flip-up mirror 8, and is captured by a television camera 16 as a fundus image Pr. The light flux from the focusing light source 14 is reflected by the small mirror 3 and illuminates the fundus Er of the eye E to be examined in a point shape. The reflected light flux on the fundus Er is captured by the television camera 16 as a focused light flux image Pf, and is displayed on the television monitor 18 together with the fundus image Pr. The signal control means 17 is the television monitor 1
The video signal of the central part of the screen is extracted from 8 and the focused light flux image
The two-dimensional position of Pf is detected, and the driving means 10 is controlled based on this position information to drive the cross cylinder lens 5 and the focusing lens 6 to correct astigmatism and focus.
When the subject is in focus, the flip-up mirror 8 is retracted from the optical path O1, and the fundus image Pr is recorded on the film 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera used in an ophthalmology clinic or the like.

[0002]

2. Description of the Related Art It is known that a conventional fundus camera performs a focusing operation by projecting a light beam on the fundus of an eye to be examined and receiving a reflected light beam at the fundus during alignment. The light flux projected onto the fundus is projected onto the fundus of the pupil of the eye to be examined from outside the pass region of the photographing light flux, and the fundus reflected light flux is received through the photographing diaphragm.

[0003]

However, in the above-mentioned conventional example, since only one-dimensional information of the fundus reflected light beam received at the time of focusing is used, astigmatism is corrected when the subject's eye has astigmatism. Because you can't
The focus cannot be adjusted properly.

Further, in order to separate the projection light beam for focusing and the photographing light beam on the pupil plane of the eye to be inspected, the projection optical system for focusing is not a fixed type but has a movable part, which complicates the structure. Has become.

A first object of the present invention is to provide a fundus camera capable of adjusting the focal length with high accuracy even in an eye to be inspected having astigmatism.

A second object of the present invention is to provide a fundus camera provided with focusing means having few mechanically movable parts and a simple structure.

[0007]

A fundus camera according to a first aspect of the present invention for achieving the above object is a projection optical system for projecting a light beam from the outside of a pass band of a photographing light beam onto a fundus of a subject's eye.
A light receiving optical system that causes the two-dimensional optical position sensor to receive the fundus reflected light by the light flux through a diaphragm that is conjugate with the pupil of the fundus imaging optical system, and a focusing unit that focuses by a signal from the two-dimensional optical position sensor. It is characterized by having.

The fundus camera according to the second aspect of the invention is a projection optical system for projecting a light beam from the outside of a pass band of a photographing light beam onto a fundus of a pupil of an eye to be examined through a fixed optical system, and a fundus reflected light by the light beam. It is characterized in that it has a light receiving optical system for allowing an optical position sensor to receive light through a diaphragm conjugate with a pupil in the photographing optical system, and a focusing means for focusing based on a signal from the optical position sensor.

[0009]

The fundus camera of the first invention having the above-mentioned structure is
The two-dimensional optical position sensor receives the reflected light beam from the fundus of the eye to be inspected by the projected light beam for focusing, and the focusing operation is performed based on this light receiving position.

Further, the fundus camera of the second invention projects a light beam for focusing from the outside of the pass band of the photographing light beam to the fundus of the eye to be inspected through the pupil of the eye to be inspected, and reflects the light beam reflected by the fundus. Light is received by the optical position sensor and focusing operation is performed based on the light receiving position.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. FIG. 1 is a configuration diagram of the first embodiment. An objective lens 1 is arranged on the optical path O1 of the eye E in the visual axis direction so as to face the eye E, and behind the objective lens 1, A perforated mirror 2, a small mirror 3 provided at the opening of the perforated mirror 2, an imaging diaphragm 4 conjugate with the fundus Er of the eye E to be examined,
A cross cylinder lens 5 composed of two cylindrical lenses having the same refractive power, a focusing lens 6, an imaging lens 7, a flip-up mirror 8, and a film 9 are sequentially arranged. The two cylindrical lenses of the cross cylinder lens 5 are rotated in opposite directions by the drive means 10, and the focusing lens 6
Are movable along the optical path O1.

Further, the optical path O2 in the incident direction of the perforated mirror 2
A lens 11 and a light source 12 for retinal illumination such as a halogen lamp or a strobe tube are arranged on the upper side, and a fixed optical member 13 and a light source 14 for focusing are arranged on an optical path O4 in the incident direction of the small mirror 3. . Further, a lens 15 and a television camera 16 are arranged on the optical path O5 in the reflection direction of the flip-up mirror 8, and the outputs of the television camera 16 are connected to a signal control means 17 and a television monitor 18, respectively. The output is connected to the driving means 10.

During alignment and fundus observation, the fundus illuminating light source 12 and the focusing light source 14 are turned on. The light flux from the fundus illuminating light source 12 passes through the lens 11, is reflected by the perforated mirror 2 and passes through the objective lens 1, and the subject's eye E
Illuminate the fundus Er of. The light flux reflected by the fundus Er returns through the same optical path, passes through the aperture of the perforated mirror 2, the photographing diaphragm 4, the cross cylinder lens 5, the focusing lens 6, and the imaging lens 7,
The light is reflected by the flip-up mirror 8, passes through the lens 15, and is captured by the television camera 16 as a fundus image Pr and displayed on the television monitor 18.

Further, the light beam emitted from the focusing light source 14 passes through the fixed optical member 13, is reflected by the small mirror 3 and passes through the objective lens 1, and illuminates the fundus Er of the eye E to be examined pointwise.
This reflected light flux at the fundus Er returns to the optical path in the same manner as the photographing light flux by the fundus illuminating light source 12, is reflected by the flip-up mirror 8, and is imaged by the lens 15 as a focused light flux image Pf by the television camera 16 to obtain a fundus image. It is displayed on the TV monitor 18 together with Pr. The signal control means 17 including a memory and a computer extracts the video signal of the central portion of the screen from the television camera 16, calculates the two-dimensional light receiving position of the focused light flux image Pf, and the driving means based on the calculation result. 10, the cross cylinder lens 5 and the focusing lens 6 are driven to correct astigmatism and focus.

FIG. 2 shows a light flux passage area on the pupil Ep plane of the eye E to be examined, and the fundus illumination light flux Lr from the fundus illumination light source 12 is shown.
Is imaged in a ring shape by the pupil Ep and projected on the fundus Er,
The reflected light flux at Er is taken out as the imaging light flux Lp from the inside of the fundus illuminating light flux Lr on the pupil Ep by the imaging diaphragm 4. Further, the focused light flux Lf from the focusing light source 14 passes through the region between the fundus illumination light flux Lr and the photographing light flux Lp, and in the focused state, the focused light flux image Pf on the fundus Er is the photographing light flux Lp. And an image is formed at a predetermined position on the line of intersection of the plane connecting the centers of the focused light flux Lf and the fundus Er surface.

In the defocused state, the focused light flux image Pf deviates from a predetermined position on the fundus Er along the line of intersection, and when the eye E to be inspected has astigmatism, the focused light flux Pf. Statue Pf
Leaves this line of intersection. The direction of separation is determined by whether the astigmatism of the eye E to be examined has a stronger vertical refractive power or a stronger horizontal refractive power. Therefore, the signal control means 17 controls the driving means 10 to rotate the two cylindrical lenses of the cross cylinder lens 5 in mutually opposite directions, so that the focused light flux image Pf is positioned in the above-mentioned intersection line in the vertical direction. Alternatively, astigmatism in the horizontal direction is generated to correct the astigmatism of the eye E, and the focusing lens 6 is further moved to the optical path O1.
The focused light beam image Pf is imaged at a predetermined position on the line of intersection, and the fundus image Pr is focused. When in focus, the flip-up mirror 8 is flipped up, and at the same time, the photographing light source of the fundus illumination light source 12 emits light to record the fundus image Pr on the film 9.

Here, the cross cylinder lens 5 may be omitted in order to simplify the structure. In this case, the astigmatism of the eye E to be inspected cannot be completely corrected, but since the light receiving position of the focused light flux image Pf is brought closest to the predetermined position, the focused light flux image Pf has a minimum circle of confusion on the fundus Er. The focusing lens 6 may be moved along the optical path O1 so as to form an image at a position.

Further, it is possible to perform a visual focusing operation instead of the automatic focusing operation. In this case, an alignment mark indicating the position of the focused light flux image Pf in a focused state is generated on the television monitor 18, and the examiner uses the cross cylinder so that the alignment mark and the focused light flux image Pf match. The lens 5 and the focusing lens 6 are adjusted.

However, this embodiment cannot detect astigmatism in the meridian direction perpendicular to the line connecting the center of the photographing light beam Lp and the center of the focused light beam Lf. To detect this astigmatism in the meridian direction, as shown in FIG. 3, two focused light beams La and Lb are incident from the pupil Ep of the eye E to be projected and projected onto the fundus Er, and as shown in FIG. This is possible by receiving the two focused light flux images Pa and Pb. Here, the line connecting the center of the photographing light flux Lp and the center of the focused light flux La is at a right angle to the line connecting the focused light fluxes Lp and Lb. In this case, use two focusing light sources or
The light flux from one focusing light source may be split into two by a diaphragm having two openings.

Then, in order to detect the two-dimensional light receiving positions of the focused light flux images Pa and Pb in the signal control means 17, the astigmatism and the astigmatism of the eye E to be inspected must be completely obtained from these position information. You can The signal control means 17 controls the driving means 10 based on this astigmatism information to rotate the two cylindrical lenses of the cross cylinder lens 5 in mutually opposite directions to completely correct the astigmatism of the eye E to be examined.

FIG. 5 is a block diagram showing only the main part of the second embodiment, and the other parts are the same as those of the first embodiment. On the optical path O4, the diloic prism 21 is arranged between the flip-up mirror 8 and the lens 15, and the lens 22 and the two-dimensional C are provided on the optical path O5 in the reflection direction of the diloic prism 21.
The CDs 23 are arranged, and the output of the two-dimensional CCD 23 is connected to the signal control means 17. In addition, a light source 1 for fundus illumination
2 and the focusing light source 14 emit light beams having different wavelengths, and the diloic prism 21 has a wavelength selection characteristic of transmitting the light beam of the fundus illuminating light source 12 and reflecting the light beam of the focusing light source 14. There is.

Therefore, only the fundus image Pr is picked up by the television camera 16, and the focused light flux Lf emitted from the focusing light source 14 is reflected by the diloic prism 21 and passes through the lens 22, as shown in FIG. Two-dimensional CCD as focused light flux image Pf
The light is received by 23. The signal control means 17 takes in the received light signal, obtains the two-dimensional receiving position of the focused light flux image Pf,
The cross cylinder lens 5 and the focusing lens 6 are driven so that the focused light flux image Pf is received at a predetermined position, and the fundus image Pr is focused.

Instead of the two-dimensional CCD 23, four light receiving elements 24a, 24b, 24c, 24 as shown in FIG. 7 are used.
It is also possible to use a photosensor 24 consisting of d.
The dividing lines of the light receiving elements 24a and 24b and 24d and 24c are perpendicular to the center lines of the focused light beams Lf and Lp. In this case, the focusing lens 6 is driven so that the sum of the light receiving signals of the pair of light receiving elements 24a and 24d of the photo sensor 24 and the sum b of the light receiving signals of the light receiving elements 24b and 24c are equal. Further, the cross cylinder lens 5 is driven so that the sum of the light receiving signals of the other pair of light receiving elements 24a and 24b is equal to the sum b of the light receiving signals of the light receiving elements 24d and 24c. When it comes to focus,
As shown in FIG. 7, the focused light flux image Pf is bisected by the boundary line of the light receiving elements 24 a, 24 b, 24 c, 24 d of the photo sensor 24.

FIG. 8 is a block diagram of only the essential parts of the third embodiment, which is a modification of the second embodiment shown in FIG. 5, in which the lens is formed in the optical path O5 in the reflection direction of the diloic prism 21. The wedge prism 2 in which two wedge prisms are arranged in opposite directions on a surface conjugate with the pupil Ep of the eye E behind the eye 22
5 is inserted. In this case, it becomes possible to focus only with the light flux that has passed through the photographing diaphragm 4.

The focused light flux Lf reflected by the diloic prism 21 passes through the lens 22, is divided into two by the wedge prism 25, and is received by the two-dimensional CCD 23 as focused light flux images Qa and Qb, respectively. When the fundus image Pr is out of focus when there is no astigmatism in the eye E to be inspected, the focused light flux images Qa and Qb are divided in the vertical direction from the predetermined distance determined by the wedge angle as shown in FIG. It shifts.

On the other hand, when the eye E to be inspected has astigmatism, the focused light flux images Qa and Qb are displaced in the left and right directions as shown in FIG. The signal control means 17 obtains the two-dimensional light receiving positions of the focused light beam images Qa and Qb, respectively, and adjusts the cross cylinder lens 5 to correct the lateral shift of the focused light beam images Qa and Qb, and then to focus. The lens 6 is adjusted to correct the vertical shift of the focused light beam images Qa and Qb, and the fundus image Pr is focused.

In the above description, the focused light flux Lf is reflected by the small mirror 3 and projected onto the fundus Er of the eye E to be examined, but it is reflected by the perforated mirror 2 through a part of the illumination optical path O2. Alternatively, the image may be projected onto the fundus Er of the eye E to be inspected. In particular, in the third embodiment of FIG. 8, it is also possible to project the focused light flux Lf over the ring-shaped fundus illumination light flux Lr as shown in FIG. By projecting the focused light flux Lf so as to pass through the inside of the fundus illumination light flux Lr, the focused light flux Lf comes closer to the photographing light flux Lp than the fundus illumination light flux Lr. It has the advantage that it is difficult to receive.

[0028]

As described above, since the fundus camera according to the first aspect of the invention detects the two-dimensional light receiving position of the fundus reflected light beam due to the focused light beam, the astigmatism of the eye to be examined is corrected and the fundus image is corrected. You can focus on.

Further, since the fundus camera according to the second aspect of the invention projects the focused light beam through the fixed optical system, there is no movable part and the structure can be simplified.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is a fundus illuminating light flux on a pupil of a subject's eye, a photographing light flux,
It is explanatory drawing of a focused light beam.

FIG. 3 is a fundus illuminating light flux on a pupil of a subject's eye, a photographing light flux,
It is explanatory drawing of a focused light beam.

FIG. 4 is an explanatory diagram of a fundus image and two focused light flux images.

FIG. 5 is a configuration diagram of only a main part of a second embodiment.

FIG. 6 is a front view of a two-dimensional CCD receiving a focused light beam image.

FIG. 7 is a front view of a photo sensor receiving a focused light flux image.

FIG. 8 is a configuration diagram of only a main part of a third embodiment.

FIG. 9 is a front view of a two-dimensional CCD that receives two focused light flux images when the subject's eye has no astigmatism.

FIG. 10 is a front view of a two-dimensional CCD that receives two focused light flux images when the subject's eye has astigmatism.

[Explanation of symbols]

 3 Small mirror 5 Cross cylinder lens 6 Focusing lens 9 Film 12 Light source for fundus illumination 14 Focusing light source 16 TV camera 17 Signal control means 18 TV monitor 21 Diloic prism 23 Two-dimensional CCD 24 Photo sensor 25 Wedge prism

Claims (4)

[Claims] 1. A projection optical system for projecting a light beam from the outside of a pass band of a photographing light beam onto a fundus of a subject's eye, and a fundus reflected light by the light beam is two-dimensionally emitted through a diaphragm conjugate with a pupil of the fundus photographing optical system. A fundus camera having a light receiving optical system for receiving light from a position sensor and a focusing means for focusing with a signal from the two-dimensional light position sensor. 2. The fundus camera according to claim 1, wherein the two-dimensional optical position sensor is an image sensor that captures a fundus image. 3. A projection optical system for projecting a light flux from a pass-through area of a photographing light flux on a fundus of a subject's eye to a fundus through a fixed optical system, and fundus reflected light by the light flux is not conjugate with a pupil in the fundus photographing optical system. A fundus camera comprising: a light-receiving optical system that causes an optical position sensor to receive light through a diaphragm; and focusing means that focuses on the basis of a signal from the optical position sensor. 4. The fundus camera according to claim 3, wherein the optical position sensor is an image sensor that captures a fundus image.