JPS6039380B2 - Fundus camera with focusing system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fundus camera that allows extremely easy focusing.

When focusing with conventional fundus cameras, the examiner looks through the finder and focuses while observing the aerial image of the patient's fundus, which tends to cause eye adjustment errors and When the user becomes fatigued, the effect becomes quite large, often resulting in photographs with significantly degraded image quality.

For this reason, there is currently a limit to the number of images that can be taken per day in medical examinations and the like. On the other hand, recently, devices for observing the fundus image displayed on a cathode ray tube have appeared, and in this case, the resolution of the image pickup tube that uses visible light or infrared rays, and furthermore, the resolution of the image pickup tube, which is placed just in front of the image pickup tube, has been improved. Focusing accuracy may decrease due to the resolution of the intensifier. In order to deal with this kind of difficulty, Hondekaanin previously stated in Tokuto No. 49-123618 that when the index is focused on the fundus, it appears in its original form, and when it is out of focus, it appears deformed. We proposed a focusing device for a fundus camera that appears as follows.

An object of the present invention is to change the way the index image is deformed to enable more accurate focusing in accordance with individual characteristics or morning preferences.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, E is the subject's eyeball and Ef is the fundus of the eye. 1
2 is an objective lens of a fundus camera; 2 is a perforated mirror; the perforated mirror serves to guide fundus illumination light and remove light reflected from the cornea;

3 is a first relay lens, and 5 is a second relay lens.

- 4 is a movable reflecting plate for guiding the light beam from the index projection unit M, which will be described later, and 4a is a partial mirror as shown in FIG. Reference numeral 6 denotes a ring slit plate which, as is well known, serves to remove corneal reflected light together with a perforated mirror.

7 is a condenser lens that focuses light emitted from the strobe tube 8 and tungsten lamp 10 onto the ring slit plate 6; 9 is another condenser lens that superimposes the image of the lamp 10 on the strobe tube 8.

Here, numbers 3 to 10 are illumination optical units. Also, 1
1 is a relay lens, and 12 is a light-shielding plate provided with an annular light-transmitting portion, as shown in a plan view in FIG. Reference numeral 13 denotes an index plate, and the index plate 13 has an index 13b formed by a light shielding portion 13a, as shown in FIG.

Note that the index may be formed by a light-shielding portion. Reference numeral 14 denotes a micro prism plate, which is a square pyramid or a hexagonal pyramid as shown in FIG. 2, and the index plate 13 and the micro prism plate 14 are brought into close contact with each other.

16 is a diaphragm plate, 17 is a tungsten lamp, and a condenser lens 15 focuses the light emitted from the tungsten lamp 17 onto the index plate 13.

Also open ○Aperture plate 16 is a condenser lens 15, index plate 1
3, and is conjugate with the light shielding plate 12 with respect to the prism plate 14. The elements numbered 11 to 17 above constitute the index projection unit M, and this unit M is movable in the optical axis direction. On the other hand, 18 is a photographing lens, 19 is a reversing mirror,
20' is a field lens, 21 is a reflecting mirror, 22 is an ophthalmic lens, 23 is a shutter, 24 is a film surface, 2
5 is the examiner's eyes.

The elements 19 to 24 are integrated and can be moved in all directions along the optical axis as a unit N, and the units M and N move so that the film surface 24 and the index slope 13 always have a conjugate relationship with respect to the perforated mirror 2. and move. Incidentally, it is preferable that the magnification of the photographing lens with respect to the film plane and the magnification of the relay lenses 3 and 11 with respect to the index plate 13 are made equal so that the moving amounts of the units M and N are equal. In the above apparatus, fundus illumination during observation is performed using light from a tungsten lamp 10, and the light emitted from the lamp 10 is imaged on a ring slint plate 6 by condenser lenses 9 and 7, forming a ring-shaped light beam.

This ring-shaped light is once imaged on the perforated mirror 2 by the relay lenses 5 and 3, but a ring image is again formed near the cornea of the eye E to be examined by the objective lens 1, and the fundus is illuminated. The light reflected from the fundus Ef passes through the pupil of the eye E, passes through the hole of the rear perforated mirror 2 where an intermediate image is formed by the objective lens 1, and forms a fundus image on the film surface 24 by the photographing lens 18. do. The reversing mirror 19 reflects light onto the light during observation, and the reversing mirror 19 guides the light from the fundus to the finder section, and passes through the field lens 20, the reflective mirror 21, and the eyepiece 22 to the examiner's eye 25. The fundus of the eye is observed.

On the other hand, the light from the illumination lamp 17 of the index projection unit M is partially restricted by the aperture diaphragm 16, and illuminates the index plate 13 placed near the microphone 0 prism 14 by the condenser lens 15.

This microprism has the function of dividing the incident light beam and bending the divided light beam in a direction according to the prism angle. The light that has passed through the indicator plate 13 and the microprism 14 passes through the perforated mirror 2 with respect to the relay lenses 3 and 11.
As shown in FIG. 2, one quadrangular pyramid microprism 14a, 14
Because it is deflected in four directions by b, 14c, and 14d, the fourth
As shown in the figure, there are four light beams 12a and 12 that match the prism angle.
b, 12c, and 12d reach the light shielding plate 12.

Therefore, the light that passes through the light shielding plate 12 is limited to only the light that is limited by the light-transmitting portion and the light that passes through, as shown by the shaded area in FIG. This light flux is once formed into an image near the mirror surface 4a of the reflector.
After reflection, the light passes through the relay lens 3, the perforated mirror 3, and the objective lens to reach the fundus Ef of the eye E to be examined. In this way, an image of the fat marker 13b is formed on the fundus Ef, but if the image is out of focus, the image will be separated depending on the shape of the microprism. This situation will be explained with reference to FIGS. 7 to 10. For convenience of explanation, it is assumed here that the size of the square pyramid of the microprism and the index are approximately the same. If the index plate is in a conjugate position with the fundus as shown in FIG. 8, the image of the index will appear on the fundus in its original form. If the conjugate position is shifted, image separation as shown in FIG. 9 or 10 will occur depending on whether the index image is formed on the front or back of the fundus.
Therefore, the examiner 25 looks through the blind eye lens 22 to visually check whether the index image is in its original shape, and moves the units M and N simultaneously until the target image is in focus. Can be combined.

Figure 11 shows the field of view in the finder when the camera is in focus. In this way, when the examiner confirms that the focus is in focus and presses the release button (not shown), the reflector 4 and reversing mirror 19 are retracted out of the optical path, a strobe tube is generated, and the shutter 23 is opened. The fundus image is imprinted on the film surface 24.

At this time, the luminous flux from the index projection unit M is not mixed into the illumination light beam, so that the image of the index is not imprinted on the film. In the device described above, the film surface 24 is slightly moved in the optical axis direction to focus the fundus camera, but the lens in the photographing optical path may also be moved for focusing.
In the case of a fundus camera, an imaging lens and an infrared imaging tube are placed at the position of the examiner 25, and infrared or near-infrared filters are provided in front of each of the lamps 10 and 17, and the fundus image is observed on a monitor. If the mirror surface portion 4a of the reflection plate 4 is made of a dichroic mirror that reflects infrared rays and transmits visible light, it is possible to carry out the photographing without retracting the reflection plate 4 from the optical path. Furthermore, in this embodiment, although the index plate 13 and the microprism plate 14 in the index projection unit M are provided in close contact with each other, the first
As shown in Figure 2, a plurality of light beams divided by the micro prism 14 may be projected onto the index plate 13 like a relay lens 26, or conversely, the image of the index plate may be projected onto the micro prism. .

FIG. 13 shows another embodiment of the invention. In the drawings, the same members as those in the embodiment of FIG. 1 are given the same numbers. 30 again
is a relay lens, and when in focus, the index plate 13 and the fundus Ef are connected to the relay lens 30 and the objective lens.
is conjugate. A condenser lens 31 forms images of the strobe tube 8 and tungsten lamp 10 onto the index plate 13 and the microprism plate 14.

30 is an infrared or near-infrared filter.

35 is a circular open square plate which, together with the ring slit plate 6, removes corneal reflected light.

36 is an imaging lens, 37 is an infrared vidicon, and a display monitor is omitted.

If the infrared filter 32 is removed and a visible light vidicon is installed instead of the infrared vidicon, normal light television observation can be performed, and if a camera tube with an image intensifier is used, weak light can be observed. It is also possible to observe the fundus using visible light. Further, the index plate 13 (FIG. 14) and the microprism plate 14, which has a size that covers at least the index portion 13a, are in close contact with each other, and move in conjunction with the unit N, so that the film surface 24 and the index plate 13 with respect to the perforated mirror are closely connected. Mechanically kept conjugate.

When the release button is pressed, the index plate 13 and the microprism plate 14 are retracted out of the optical path in the direction of the white arrow immediately before the strobe tube 8 emits light. In the above-described device, the light emitted from the lamp 10 is divided into a plurality of light beams (four directions in the case of a square key prism) by the microprism plate 14, and illuminates the index plate.

FIG. 15 is a plan view of the ring slit plate 6, and the light beam passing through this ring slit is the light beam in the area where the slit and four light beams overlap, as shown by diagonal lines in FIG. , are incident on the subject's eye in four different directions without interfering with each other.

On the other hand, reflected light generated at the fundus passes through the objective lens 1, photographing lens 18, reversing mirror 19, field lens 20, reflecting mirror 21, and photographing lens 36, and forms an image on the pseudo-twill surface of the vidicon 37. Therefore, the examiner looking at the image on the monitor (not shown) observes the original or deformed index image, and if the index image is deformed, unit N and index plate 1
Adjust the focus by moving 3 and adjust the index image as much as possible to its original shape. When the focus is confirmed by visual confirmation of the index image, press the reset button, the index plate 13 and prism plate 14 will unite and retreat out of the optical path, and after the reversing mirror 19 has rotated, The strobe tube 8 emits light and images the fundus of the eye onto the film surface 24.

On the other hand, FIG. 17 shows a system corresponding to the index projection unit N in FIG. 1, which includes four lenses (15a, 15b, 15c, 15
d, two of which are not shown) and lamps (17a, 17b, 17
(c, 17d, two of which are not shown) provides a light beam in four directions, and has an effect similar to a microprism consisting of a four-sided pyramid, but the microprism is smaller than that of such a structure. If a prism is used, it has the advantage of being much smaller.

The present invention described above is a fundus camera that keeps the image plane constant and mechanically interlocks and adjusts the index so that the relationship between the index and the fundus is always equal to the relationship between the image plane and the fundus. A microprism is used to generate multiple component light beams containing information about 4.
・It has an effect that corresponds to the type and individuality of each person.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an embodiment of the present invention. FIG. 2 is a plan view of a microprism which is a component of the embodiment, FIG. 3 is a plan view of an index plate, and FIG. 4 is a plan view of a ring slit plate. FIG. 5 is an explanatory diagram of the action of the ring slit plate and the microprism. FIG. 6 is a plan view of the reflector. FIG. 7, FIG. 8, FIG. 9, and FIG. 10 are diagrams for explaining the correspondence between the focus state and the index image. FIG. 11 is a diagram showing the field of view when looking through the finder, and FIG. 12 is a modified diagram of the index projection unit. FIG. 13 is a side sectional view showing another embodiment. FIG. 14 is a plan view of the index plate, and FIG. 15 is a plan view of the ring slit plate. FIG. 16 is a diagram explaining the action of the IJ ring slit plate and the microprism. FIG. 17 is an exemplary diagram for comparing index projection units. In the figure, 1 is an objective lens, 2 is a perforated mirror, 3 and 30 are relay lenses, and 6
1 is a ring slit plate, 1 is a relay lens, 12 is a light-shielding plate with an annular transparent part, 13 is an index plate, 14' is a micro prism, and 10 and 17 are tungsten lamps. Traditional map, 2 maps, multiple maps, 4 maps, grandsons, 5 maps, multiple maps, 8 maps? ``Double brother'〃Zutsume'' ``Dear brother's drawings''

Claims (1)

[Scope of Claims] 1. A fundus having a focusing system in which the index image projected onto the fundus appears in its original form when it is focused on the fundus, and appears deformed when it is out of focus. A fundus camera equipped with a focusing optical system characterized in that the optical system for projecting an index image has a microprism. 2. The microprism is provided on the side of an optical system for observing and photographing the fundus of the eye, and is disposed in the optical system for guiding fundus illumination light. A fundus camera equipped with a focusing optical system. 3. The target image projection light flux from the target image projection optical unit containing a built-in microprism is guided to the optical system provided on the side of the optical system for observing and photographing the fundus, and for transmitting the fundus illumination light. A fundus camera equipped with a focusing optical system according to claim 1, which emits light.