JPH0966031A - Fundus camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exactly perform focusing by letting by letting light flux hardly get vignetting even when an alignment is deviated by receiving light reflected from the eyeground at an array sensor respectively as plural pieces of light flux and finding a focus signal from its position information. SOLUTION: The light flux from a light source 23 for focusing passes through a dichroic mirror 18, switching mirror 6 and objective lens 7' and projects spot light on the eyeground Er. The light reflected from the eyeground Er is reflected on an aperture mirror 2 and a reflection plane 10a of a beam splitting member 10 and passed through a lens 13, diaphragm 14, separate prism 15 and lens 16, two light flux images are received at a linear CCD 17 and fetched into an arithmetic control means 24, their positions are analyzed and the refraction factor of the eye E to be checked is found. Besides, the position information of a focus lens 4 detected by an encoder 8 is fetched into the arithmetic control means 24, the measured refraction factor is arithmetically compared with a refraction factor corresponding to the position of the focus lens 4, and a split mark M generated by a signal emitting circuit is displayed while being superimposed on an eyeground image E'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera for photographing a fundus of an eye to be examined by photographing a plurality of light beams and performing alignment.

[0002]

[Prior art]

(1) Conventionally, when obtaining a focusing signal with an array sensor in a fundus camera, there are a method of receiving a single light flux that is not divided by a focusing sensor and a method of using a signal of an image sensor for fundus observation. Further, there is known a method in which a light beam projected from one position around the pupil passes through an imaging diaphragm and is then divided to receive light.

(2) Further, as a conventional method of displaying the direction and degree of focusing, a method of projecting a split light beam on the fundus and observing the image together with the fundus image, or focusing near the fundus image. There is a method of detecting and displaying whether or not there is.

[0004]

[Problems to be Solved by the Invention]

(B) However, in the above-mentioned conventional example (1), when a single light flux is received by the focusing sensor or when the signal of the image sensor for observation is used, the light flux is eclipsed when the alignment is misaligned. However, there is a problem that the focus cannot be detected.

(B) Further, in the above-mentioned conventional example (2),
When observing split light projected on the fundus, there is a drawback that it is difficult to see when the split image overlaps with a bright part such as the nipple, and when displaying the focus near the fundus image,
Since the direction and degree of focusing are unknown, it is difficult to perform positioning, and there is a problem that it is inconvenient to photograph an object in front of and behind the retina surface.

A first object of the present invention is to solve the above-mentioned problem (a).
SUMMARY OF THE INVENTION It is an object of the present invention to provide a fundus camera in which the light beam is hard to be eclipsed even if the alignment is deviated and the focus can be accurately focused.

A second object of the present invention is to solve the above problem (b).
It is an object of the present invention to provide a fundus camera which can be easily viewed and aligned regardless of the fundus of the eye.

[0008]

A fundus camera according to a first aspect of the invention for achieving the above object is a light splitting device for splitting an illumination optical system and a photographing optical system in the vicinity of a conjugate position with a pupil of an eye to be examined of an objective lens. In a fundus camera equipped with a member, a focused light beam is projected from the center of the pupil or from a plurality of positions around the pupil, and reflected light from the fundus is received by the array sensor as a plurality of light beams. It is characterized by having a detection means for obtaining a signal.

A fundus camera according to a second aspect of the present invention is a projection optical system for projecting a focused light beam onto the fundus of an eye to be inspected, and a light receiving optical system for dividing reflected light from the fundus into a plurality of light beams and receiving them by an array sensor. And a calculation means for calculating a focus state based on a signal of the light receiving optical system, and a display means for displaying a focus direction and degree calculated by the calculation means.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows a configuration diagram of a fundus camera of the first embodiment, in which an objective lens 1, a pupil Ei, a perforated mirror 2 near a conjugate position, and a pupil Ei are provided on an optical path O1 in front of an eye E to be examined.
The photographic diaphragm 3, the focus lens 4, the photographic lens 5, the switching mirror 6 that jumps up from the optical path O1 at the time of shooting, and the film 7 are sequentially arranged.
Is connected to the encoder 8.

A lens 9, a light splitting member 10 having a reflecting surface 10a for reflecting focused light, a lens 11, and a light source 12 such as a lamp or a strobe are sequentially arranged on an optical path O2 in the incident direction of the perforated mirror 2. The lens 13 is provided on the optical path O3 in the reflection direction of the light splitting member 10 as shown in FIG.
A diaphragm 1 having individual apertures 14a and 14b and conjugate with the pupil Ei
Separation prism 1 with 4 and 2 wedge prisms facing each other
5, a lens 16, and a linear CCD 17 conjugated to the standard eye fundus are sequentially arranged.

A dichroic mirror 18, a lens 19, and a television camera 20 are sequentially arranged on the optical path O4 in the reflection direction of the switching mirror 6, and the dichroic mirror 18 is provided.
On the optical path O5 in the reflection direction, a small aperture diaphragm 21 that is substantially conjugate to the diaphragm 3, a lens 22, and a focusing light source 23 such as an LED having a different wavelength from the light source 12 are sequentially arranged. The outputs of the encoder 8, the television camera 20 and the linear CCD 17 are connected to the arithmetic control means 24 and the television monitor 25.

The light flux from the light source 12 is a lens 11, a light splitting member 10, a lens 9, a perforated mirror 2, and an objective lens 1.
The fundus Er of the eye E to be inspected is illuminated through. Reflected light from the fundus Er passes through the objective lens 1, the perforated mirror 2, the photographing diaphragm 3, the focus lens 4, and the photographing lens 5, is reflected by the switching mirror 6 during observation, passes through the dichroic mirror 18, and is reflected by the lens 19 at the fundus. The image is formed on the television camera 20, and the fundus image E ′ is displayed on the television monitor 25.
Then, at the time of photographing, the switching mirror 6 is flipped up and a fundus image is photographed on the film 7.

The light flux from the focusing light source 23 is reflected by the lens 2
2, a small aperture diaphragm 21, a dichroic mirror 18, a switching mirror 6, a taking lens 5, a focus lens 4, a diaphragm 3, a perforated mirror 2 and an objective lens 1 to project spot light onto the fundus. The reflected light from the fundus Er is reflected by the perforated mirror 2 and the reflecting surface 10a of the light splitting member 10, passes through the lens 13, the diaphragm 14, the separating prism 15 and the lens 16, and is reflected by the linear CCD 17 as shown in FIG. Two luminous flux 2
3'is received. The signal from the linear CCD 17 is taken into the arithmetic control means 24 including a symbol generating circuit, and the light flux image 2
The position of 3'is analyzed to obtain the refractive index of the eye E to be inspected.

On the other hand, the position information of the focus lens 4 detected by the encoder 8 is similarly taken into the arithmetic control means 24, and each position of the focus lens 4 is associated with the refraction index. The calculation control means 24 calculates the measured refraction index and the refraction index corresponding to the position of the focus lens 4.
The calculation is compared in step S3 and the split mark M as shown in FIG. 4 generated by the symbol generation circuit in the calculation control means 24 is displayed on the fundus oculi image E '. Figure 4 when the refraction index is correct
As shown in (a), the split mark M becomes a straight line, and depending on whether it is in front or behind, the split mark M is split leftward as shown in (b) or rightward as shown in (c). .

The degree of splitting of the split mark M changes in accordance with the difference in the refraction index, which makes it easy to focus because it is possible to see in what direction and to what extent it does not fit. You can also shoot. Further, since the split mark M is displayed as a character, edging and the like are easy, and the split mark M is not difficult to see even in the bright part of the fundus oculi image E ′.
Since the focused light is projected from the center of Ei, there is no possibility that the signal cannot be detected even if the subject's eye E moves a little.

Further, even if one of the light fluxes is deflected, if one of them is detected, the refraction degree can be calculated from the difference of the light flux from a predetermined position, and the split mark M can be displayed. It should be noted that if a stepping motor is attached instead of the encoder 8 and the focus lens 4 is driven based on the measured refraction index, autofocusing becomes possible, and it is possible to switch between manual and automatic modes. The split mark M may be displayed.

In the above description, the degree of refraction of one meridian is measured and focused, but the diaphragm 14 is the diaphragm 26 having four openings 26a to 26d as shown in FIG.
If the area CCD 27 shown in FIG. 6 is used in place of D17, the refractivity of two meridians can be measured. As shown in FIG. 6, the area CCD 27 includes the apertures 26 a of the diaphragm 26.
It is also possible to receive the four light fluxes 23 'from 26d to detect their positions, provide a cross cylinder in the vicinity of the diaphragm 3, and drive them from the difference in refraction of two meridians to correct astigmatism. it can.

FIG. 7 is a block diagram of the fundus camera of the second embodiment, in which the lens 13, the diaphragm 14, the lens 16, and the split prism 30 are provided on the optical path O3 in the reflecting direction of the reflecting surface 10a of the light dividing member 10. , Two openings 31 as shown in FIG.
A two-hole aperture 31 having a and 31b and a focusing light source 32 that emits light having a wavelength different from that of the light source 12 are sequentially arranged. Further, there is no member on the optical path O5 in the reflection direction of the half mirror 18 in FIG. 1, and the other parts have the same configuration as in FIG.

In this case, the focused luminous flux is projected from the illumination optical path, received by the CCD television camera 20 for photographing, and the video signal is taken into the arithmetic control means 24 for focusing. The light flux from the focusing light source 32 passes through the two-hole diaphragm 31, the split prism 30, the lens 16, the diaphragm 14, and the lens 13 and is reflected by the reflecting surface 10a of the light splitting member 10 to surround the pupil Ei of the eye E to be examined. Two light fluxes are projected onto the fundus Er from the two positions. At this time, the openings 31a and 31b of the two-hole diaphragm 31
The respective luminous fluxes from are refracted by the prism 30 and pass through the aperture 14a or 14b of the diaphragm 14.

FIG. 9 shows a focused light flux image 31 'projected on the fundus.
(A) is emmetropia, (b) is hyperopia, and (c) is myopia. Further, FIG. 10 shows a television camera 20.
The image photographed in Fig. 2 shows a fundus image E'and a focused light flux image 31 'at the center of the fundus, and the position of the light flux image 31' is calculated from this video signal to obtain the refractivity.

FIG. 11 shows an image on the television monitor 25 at this time, and the light flux image 31 'becomes a split mark N in the display area L. In this case as well, even when one of the light fluxes is eclipsed, the degree of refraction can be obtained from the position of the other light flux, and the split mark N can be displayed.

When the fundus observation is performed by the optical viewfinder, an optical viewfinder is used instead of the television camera 20 shown in FIG. 1, and three LEs are provided at a conjugate position with the fundus Er in the optical system.
When D33, 34, and 35 are arranged, the focusing direction and degree can be displayed as shown in FIG. For example, the green LED 36 is turned on when focusing, and the red LEDs 35 and 37 are turned on when front focusing and rear focusing, respectively. Also, when they are almost matched, the red LED 35 and the green LED 36 or the green LED 36
And the red LED 37 may be alternately turned on.

[0024]

As described above, the fundus camera according to the first aspect of the invention receives the reflected light from the fundus at a plurality of positions and obtains the focusing signal from those positions, so that the luminous flux can be changed even if the alignment is deviated. There is no shading, and the focusing signal is always obtained from the remaining one light beam, so there is no failure in shooting.

In the fundus camera according to the second aspect of the invention, the fundus reflected light is divided into a plurality of luminous fluxes and received, and the focusing direction and degree are displayed, so that the focusing operation is facilitated and the retinal surface is displayed in front. It is also convenient when photographing a certain object, and can perform fundus photography in a wide range of applications.

Further, the first and second inventions have a simple structure because the focusing system has no movable part other than the focus lens.

[Brief description of drawings]

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

FIG. 2 is a front view of a two-hole aperture.

FIG. 3 is an explanatory diagram of a focusing light source image on a linear CCD.

FIG. 4 is an explanatory diagram of a split mark.

FIG. 5 is a front view of a four-hole diaphragm.

FIG. 6 is an explanatory diagram of a focusing light source image on an area CCD.

FIG. 7 is a configuration diagram of a second embodiment.

FIG. 8 is a front view of a two-hole diaphragm.

FIG. 9 is an explanatory diagram of focused light on a fundus image.

FIG. 10 is an explanatory diagram of a fundus image on a television camera.

FIG. 11 is an explanatory diagram of a fundus image on a television monitor.

FIG. 12 is an explanatory diagram of an LED showing a focusing direction and degree.

[Explanation of symbols]

 2 Perforated mirror 3, 14, 21, 31 Aperture 6 Switching mirror 7 Film 10 Light splitting member 12, 23, 32 Light source 15 Separation prism 17 CCD 18 Half mirror 20 Television camera 24 Arithmetic control means 25 Television monitor 30 Split prism

Claims (2)

[Claims] 1. A fundus camera having a light splitting member for splitting an illumination optical system and a photographing optical system in the vicinity of a conjugate position with a pupil of an eye to be inspected of an objective lens, wherein a plurality of focused light fluxes are provided from the center of the pupil or around the pupil. A fundus camera having a detecting means for projecting light from a spot, receiving reflected light from the fundus as a plurality of light beams by an array sensor, and obtaining a focusing signal from position information of the plurality of light beams. 2. A projection optical system for projecting a focused light beam onto the fundus of the eye to be inspected, a light receiving optical system for dividing reflected light from the fundus into a plurality of light beams and receiving them by an array sensor, and a signal of the light receiving optical system. A fundus camera comprising: a calculation unit that calculates a focus state based on the calculation unit; and a display unit that displays the direction and degree of the focus calculated by the calculation unit.