JPH07124117A - Stereoscopic fundus camera - Google Patents

Abstract

PURPOSE:To easily and accurately judge an aligning state by providing a photodetecting means to detect incident light quantity on right and left photographic optical systems, a comparison means, a judging means to judge the normal/defective condition of the aligning state based on a comparison result, and an informing means to report a judged result. CONSTITUTION:Reflected light from an eyeground, after being reflected upward by return mirrors 22a, 22b, is introduced to relay lenses 23a, 23b, dichroic mirrors 24a, 24b, a mirror member 25, a deflection prism 26, and an image-forming lens 27, and is image-formed on right and left image pickup elements 28, respectively. Video signals from the image pickup elements 28 are digital-converted by an A/D converter 54 by making synchronize with a signal from a horizontal counter 53, and is fetched in memory 55. The memory 55 stores by cumulatively adding the light quantity of right and left photographic images on a horizontal scanning line by the control of a CPU 56, respectively. It is judged whether or not the light quantity difference of accumulated light quantity of right and left images is within a prescribed value, and when it is within a specific value, it is judged that alignment can be taken, and it is judged that a defective condition occurs when it is a value outside the specific value, then, judgement for the normal/defective condition is reported on a TV monitor, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simultaneous photographing type stereoscopic fundus camera, and more particularly to a mechanism for determining whether or not alignment between an eye to be inspected and an apparatus is good.

[0002]

2. Description of the Related Art A simultaneous photographing type stereoscopic fundus camera in which a reflected light beam from a fundus of an eye to be examined is divided by a two-hole diaphragm and each divided light beam is photographed by a pair of left and right photographing optical systems to obtain a pair of stereo images. It has been known. The examiner observes the fundus image (and the anterior segment) through the binocular eyepiece or monitor to determine empirically whether the alignment of the device with respect to the subject's eye is good or bad.

[0003]

The above-mentioned alignment method has an advantage that the alignment state can be judged quickly and simply, but since the observation image constantly changes, such as the blink of the eye to be inspected or the movement of the eyeball, Accurate judgment is difficult. Therefore, although the alignment is actually poor, it is not uncommon for the examiner to judge that the alignment is completed, and it is often seen by a photographer with little experience. There is a case where a good quality captured image cannot be obtained due to uneven light amount or flare light mixed in the captured image captured in the state of poor alignment, and re-imaging is required. In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a simultaneous photographing type stereoscopic fundus camera capable of easily and accurately determining the alignment state without requiring skill. A second object of the invention is to provide a fundus camera capable of preventing photographing in a poorly aligned state.

[0004]

The present invention is characterized by having the following constitution in order to achieve the above object. (1) In a stereoscopic fundus camera in which a reflected light beam from the fundus of the eye to be inspected is divided by a two-hole diaphragm, and the divided light beams are photographed by a pair of left and right photographing optical systems to obtain a pair of stereo images. A light detecting unit that detects the amount of light incident on the system, a comparing unit that compares the amount of light incident on the left and right imaging optical systems based on the detection result of the light detecting unit, and whether the alignment state is good or bad based on the comparison result of the comparing unit. It is characterized by having a judging means for judging and a notifying means for notifying the examiner of the judgment result of the judging means.

(2) The light detecting means of (1) is one image pickup device, and is characterized by having a light guiding optical system for guiding an illumination light flux from a pair of left and right photographing optical systems to the image pickup device.

(3) The light detecting means of (1) is an image pickup device, and the comparing means compares the accumulated light amounts on one horizontal scanning line of the image pickup device.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. [Structure] FIG. 1 is a schematic layout view of an optical system when an embodiment of the present invention is viewed from the side, and includes an illumination optical system, a photographing optical system, and an observation optical system. 2 is a sectional view taken along the line AA of the photographic optical system of FIG. 1 as seen from above, and FIG. 3 is a sectional view taken along the line BB of the portion of the observation optical system shown in FIG. 1 as seen from the left side. (Illumination optical system) 1 is a halogen lamp which is an illumination light source for observation, 2 is a condenser lens for a halogen lamp, and 3 is used when performing so-called non-mydriatic imaging using natural mydriasis in a dark place of a subject. Infrared filter for making the illumination light for observation invisible light, 4 is a flash lamp as an illumination light source for photographing, and 2'is a condenser lens for a flash lamp.

Reference numeral 5 is a beam splitter, 6 is a condenser lens, and 7 is a ring slit which is a ring-shaped aperture stop. The shape of the ring slit 7 is shown in FIG. 8
Is a mirror for changing the direction of the optical path, and 9 is an illumination system relay.
Reference numeral 10 denotes a lens having a small black spot in the center thereof for removing harmful light, 11 an illumination system relay lens, and 12 a perforated mirror having an opening for photographing light flux in the center. The halogen lamp 1 for observation and the flash lamp 4 for photographing are arranged at conjugate positions by the condenser lenses 2 and 2 ', and both light fluxes are coaxially combined via the beam splitter 5 to illuminate the ring slit 7. . Ring slit 7
The luminous flux of the
An intermediate image is formed in the vicinity of the opening of No. 2 and is reflected by the mirror surface of the donut shape, becomes coaxial with the optical axis of the objective lens shown in 13, and the image of the ring slit 7 is formed in the vicinity of the pupil of the eye 14 to be inspected. An image is formed and diffused in the eye 14 to be inspected to illuminate the fundus.

(Photographing optical system) 13 is an objective lens which is also used as an illumination optical system, and 15 is a two-hole diaphragm which divides a light beam into left and right for stereoscopic observation and photographing. The two-hole aperture 15 is shown in FIG. Reference numerals 16 and 17 denote light beam separating prisms, and 16 has a function of switching the left and right of the divided light beam so as to prevent the stereo image from becoming an inverse stereoscopic body, and 17 has a function of keeping the subsequent light beams in parallel at a predetermined interval. Fulfill
Reference numeral 18 is a relay lens, and 19 is a focusing lens, which is movable in the optical axis direction and enables adjustment according to the refractive power of the eye to be inspected. Numeral 22 is a return mirror for the observation optical system, which retreats to the position indicated by the broken line during photographing. An image forming lens 20 forms an image of the fundus on the film surface of 21. The reflected light from the fundus of the eye 14 to be examined forms an inverted intermediate image at the point C by the eye lens to be examined and the objective lens 13 and then passes through the aperture of the perforated mirror 12 to separate the light flux by the two-hole diaphragm 15. Will be
Since this two-hole diaphragm is arranged so as to be conjugate with the pupil of the eye to be inspected through the objective lens 13, the light beams divided into right and left for stereo on the pupil are matched at point C and separated again. That is, the size of the light flux for photographing is practically determined on the pupil plane. Further, as described above, the image of the ring slit 7 of the illumination optical system is formed in the vicinity of the pupil of the subject's eye 14.
Since the ring slit 7 and the two-hole diaphragm 15 are located at substantially conjugate positions on the pupil in this way, when the ring slit and the two-hole diaphragm on the pupil plane are overlapped, the result is as shown in FIG. Four
Reference numeral 1 is the aperture of the two-hole diaphragm 15, and 42 is the slit image of the ring slit 7.

The fundus illumination luminous flux by the ring slit 7 is
The illumination light flux is introduced by utilizing a portion on the pupil plane that does not interfere with the photographing light flux, that is, a portion mainly above and below the vertical dimension of the two light fluxes. In this embodiment, as shown in FIG. 7A, the shape of the ring slit 7 is designed so that the larger the diameter of the mydriasis, the more the light quantity enters the fundus. Even when the pupil diameter of the eye to be inspected is not sufficient and the two light fluxes 41 for photographing are full left and right as shown in FIG. 7-b, the light can be introduced from the upper and lower portions shown by 43. In the photographing optical system, the reflected light from the fundus of the eye 14 to be examined forms an inverted intermediate image at the point C by the objective lens 13, and then passes through the aperture of the perforated mirror 12, and the light flux is emitted by the two-hole diaphragm 15. To be separated. The light flux that has passed through the two-hole diaphragm and has been made parallel by the light flux separation prisms 16 and 17a, 17b is received by the relay lenses 18a, 18b, and the forward lens.
The imaging lens 2 passes through the cassing lenses 19a and 19b.
Left and right images are formed on the film surface 21 at 0a and 20b. For the fundus illumination of the eye to be inspected, the light flux from the halogen lamp 1 is used as the invisible light to the eye to be inspected by the infrared filter 3 at the time of non-mydriatic observation, but the flash lamp 3 is synchronized with the exit of the return mirror 22 at the time of photographing. Since it is used after being used, a sufficient amount of light can be obtained for instant shooting.

(Observation Optical System) The observation optical system includes the objective lens 13 of the photographing optical system to the focusing lenses 19a and 19a.
The optical system up to b is shared. Reference numerals 23a and 23b are relay lenses, 24a and 24b are mirrors for directing a light beam inward for the purpose of narrowing the optical axis, 25 is a mirror member for directing a light beam upward, and 26 is a left and right side of two images. It is a thin deflection prism for aligning positions. Reference numeral 27 is an imaging lens of the observation optical system, and 28 is an image pickup device for a TV camera such as a CCD. The reflected light from the fundus guided through the objective lens 13 to the focusing lenses 19a and 19b is the return mirror at the position indicated by the solid line except when photographing.
After being reflected upward by 22a and 22b, the relay
Lenses 23a, 23b, dichroic mirror-24a,
It is guided to the mirror 24 b, the mirror member 25, the deflection prism 26, and the imaging lens 27, and forms an image on the image pickup device 28 that is conjugate with the film surface 21.

FIG. 8 shows an example of a TV monitor screen display of an image captured by a TV camera, which is a pair of left and right image displays used for stereoscopic photography. In this embodiment, one TV
An example of a camera and one TV monitor is shown, but changes such as using dedicated TV cameras for each of the left and right and sharing only the TV monitor via the image synthesizing circuit, or using multiple TV monitors No problem whatsoever. [Block Diagram of Alignment Judgment Mechanism] FIG. 9 is a block diagram of the alignment judgment mechanism. Reference numeral 50 is a reference clock generator, and 51 is a frequency divider for giving a vertical synchronizing signal. 5
Reference numeral 2 denotes a vertical counter, and the vertical counter 52 gives a count start signal to the horizontal counter 53 at the start of horizontal scanning at a predetermined distance from the vertical scanning start position. The horizontal scanning line used for alignment determination is preferably located at a position crossing the macula.

The video signal from the image pickup device 28 is converted into a digital signal by the A / D converter 54 in synchronism with the signal of the horizontal counter 53, and is stored in the memory 55. Under the control of the CPU 56, the memory 55 cumulatively adds and stores the respective light amounts of the left and right picked-up images on the horizontal scanning line.
In the apparatus of the embodiment having the above configuration, the alignment method will be described next based on the flowcharts of FIGS. The optical system main body is housed in a casing and is mounted on an operation table that moves on a fixed table via a sliding mechanism. The photographer fixes the subject on the chin rest fixed to the fixing base. Turn on the halogen lamp 1, which is the illumination light source for observation,
The eye 14 to be inspected is illuminated. The photographer operates the operation console while looking at the observation image appearing on the TV monitor (see FIG. 8),
Move the optical system body forward, backward, left and right, up and down with respect to the eye,
Alignment is performed so that a predetermined positional relationship is established.

The alignment is determined as follows. FIG. 12 is a diagram for explaining the alignment determination. The upper part of the figure is an example of an image captured by the image sensor 28, the left side is an image by the left optical system, and the right side is an image by the right optical system. The initial position of the scanning signal of the image sensor 28 is confirmed. The vertical counter 52 operates to count the vertical clock for ΔV, and at the position where ΔV is reached, the horizontal counter 53 and the horizontal counter 53 are started at the same time. The video signal is A / D converted in synchronization with the horizontal counter 53, and the A / D converted value is cumulatively added to the memory 55 under the control of the CPU 56. The lower part of FIG. 12 shows ΔV from the upper end of the drawing (vertical scanning start position).
Video signal for one horizontal scanning line of the shifted position is shown, In one horizontal scanning period (t ₀ -t _3), the input image signal from t ₀ to t ₁ is by the left optical system, from t ₁ t ₂
Is a left / right image separation range, and t ₂ to t ₃ are input image signals from the right optical system. The cumulative addition sum of horizontal scanning from t ₀ to t ₁ is stored in the memory 55 as the total left optical system light amount (SUML). The cumulative addition buffer in the memory 55 is cleared, the horizontal clock A / D-converts the light amount from t ₂ to t _3, sequentially cumulatively adds, and the cumulative addition total is stored in the memory 55 (SUMR).

The CPU 56 determines whether or not the light amount difference (| SUMR-SUMML |) of the accumulated light amounts of the left and right images is within a predetermined value (allowable value). If it is within the predetermined value, it is determined that the alignment is OK, and if it is out of the predetermined value. Is determined to be defective in alignment. FIG. 13 shows an example of poor alignment. Since the alignment of the imaging optical axis with respect to the eye to be inspected is poor, there is a clear difference in the amount of incident light between the left and right optical systems. The value of the difference between the cumulative addition results of the respective video signals becomes a large value, and it can be seen that the alignment is defective. FIG. 14 is a diagram showing another example of poor alignment. Since the alignment of the photographing optical axis with respect to the subject's eye is poor, flare due to ambient light has occurred in the right optical system. Also in this case,
The light amount cumulative addition value in the right optical system is obviously larger than the light amount cumulative addition value in the left optical system, and it can be determined that the alignment is defective. The judgment of the quality of the alignment thus obtained is notified to the examiner by a TV monitor or an alarm.
When alignment (and focusing) is completed and a shooting button (not shown) is pressed, the return mirror 22 retreats to the position of the broken line, the xenon flash lamp 4 emits light in conjunction, and the amount of light required for the film surface 21 is the fundus. It is given to and photographed. It should be noted that even if the photographing trigger switch is pressed, if the alignment determination signal is defective, it may not be activated. Further, not only the cumulative light amount of one scanning line but also the cumulative light amount of a plurality of scanning lines may be compared.

[0016]

According to the present invention, in a simultaneous photographing type stereoscopic fundus camera which requires accurate alignment with respect to the eye to be inspected, the quality of alignment can be accurately judged in a short time. -It is effective for rings. Also,
Since there is no unevenness in the amount of light on the left and right images, it is extremely convenient for diagnosis and analysis.

[Brief description of drawings]

FIG. 1 is a schematic layout diagram of an optical system when an embodiment is viewed from the side.

FIG. 2 is a cross-sectional view taken along the line AA of the photographing optical system of FIG. 1 as seen from above.

3 is a BB view of the observation optical system portion of FIG. 1 as seen from the left side.
FIG.

FIG. 4 is a diagram showing a shape of a ring slit 7.

FIG. 5 is a diagram showing the shape of a two-hole diaphragm 15.

FIG. 6 shows a ring slit 7 and a two-hole diaphragm 15 on the pupil plane.
It is a figure which shows the state which overlapped.

FIG. 7-a is a diagram showing a portion for introducing a fundus illumination light flux.

FIG. 7-b is a diagram showing a portion for introducing a fundus illumination light flux.

FIG. 8 is a diagram showing an example of a TV monitor screen display of an image of the fundus captured by a TV camera.

FIG. 9 is a block diagram of an alignment determination mechanism.

FIG. 10 is a flowchart for explaining an alignment method.

FIG. 11 is a flowchart for explaining an alignment method.

FIG. 12 is a diagram for explaining alignment determination.

FIG. 13 is a diagram showing an example of defective alignment.

FIG. 14 is a diagram showing another example of misalignment.

[Explanation of symbols]

 7 Ring slit 15 Two-hole diaphragm 21 Film surface 26 Declination prism 28 Image sensor 50 Reference clock generator 51 Frequency divider 52 Vertical counter 53 Horizontal counter 54 A / D converter 55 Memory 56 CPU

Claims (3)

[Claims] 1. A stereoscopic fundus camera in which a reflected light beam from a fundus of an eye to be inspected is divided by a two-hole diaphragm and each divided light beam is photographed by a pair of left and right photographing optical systems to obtain a pair of stereo images. Light detecting means for detecting the amount of incident light on the photographing optical system, comparing means for comparing the amount of incident light on the left and right photographing optical systems based on the detection result of the light detecting means, and the alignment state based on the comparison result of the comparing means. A stereoscopic fundus camera, comprising: a determination unit that determines pass / fail, and a notification unit that notifies an examiner of a determination result of the determination unit. 2. The stereoscopic fundus camera, wherein the light detecting means of claim 1 is one image pickup device and has a light guiding optical system for guiding an illumination light flux from a pair of left and right photographing optical systems to the image pickup device. . 3. The stereoscopic fundus camera according to claim 1, wherein the light detecting means is an image pickup device, and the comparing means compares the accumulated light amount on one horizontal scanning line of the image pickup device.