JPH0538329A - Ophthalmic image pick-up device - Google Patents

Abstract

(57) [Abstract] [Purpose] Even when the tilt angle of the subject is large, it is possible to obtain an image of uniform magnification focused on the entire screen. [Structure] A light flux reflected by an object SO is imaged on an image sensor 3 by a lens 1. The tilt angles of the lens 1 and the image pickup device 3 are changed according to the tilt angle of the subject SO with respect to the photographing optical axis O1, and since these constitute a Scheimpflug optical system, the image pickup device 3 focuses on all parts of the subject SO. The existing image is captured. Since the magnification of this image is different in each part, the magnification is corrected by the computer 5, and after correction, an image of uniform magnification focused on all the parts is output to the television monitor 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eye imaging device applicable to, for example, an intracorneal imaging device.

[0002]

2. Description of the Related Art Conventionally, for example, in a corneal endothelial cell imaging device, a photographing lens system is generally arranged perpendicularly to a photographing optical axis, and the reflection angle on the inner surface of the cornea is not so large. The separable range becomes narrower, and only the narrow area of the corneal endothelium can be used for focused imaging.

If the lens system is simply tilted in order to avoid this, there is a drawback in that it is difficult to accurately grasp the condition of the subject because the image pickup magnification is different in each part of the screen.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional example, and to provide an eye image pickup apparatus capable of obtaining an image of uniform magnification focused on the entire screen even if the tilt angle is large. To provide.

[0005]

In order to achieve the above object, an eye image pickup apparatus according to the present invention is an eye image pickup apparatus for picking up a predetermined portion of an eye to be inspected as a subject in an image pickup unit. And an image forming unit whose lens optical axis is rotationally displaced from the image capturing optical axis in accordance with the inclination from, and a unit for making the magnification constant at each position imaged through the image forming unit. It is what

[0006]

The eye image pickup apparatus having the above-mentioned structure adopts, for example, a Scheimpflug optical system, and makes the magnification of each part of the image constant by using a correction coefficient determined by the arrangement of the Scheimpflug optical system.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. FIG. 1 shows a block diagram of the first embodiment, in which the photographing optical axis O1
The lens 1 is arranged so as to face the subject SO arranged above, and the two-dimensional image pickup device 3 of the television camera 2 is arranged behind it. The output of the television camera 2 is connected to the image memory 4, the output of the image memory 4 is connected to the computer 5, and the output of the computer 5 is connected to the television monitor 6. The lens optical axis of the lens 1 and the image pickup element 3 can change the tilt angle with respect to the photographing optical axis O1, and constitute a Scheimpflug optical system for the subject SO at the time of image pickup.

The light flux reflected by the subject SO is imaged on the image pickup device 3 by the lens 1. In this Scheimpflug optical system, even if the subject SO is largely tilted with respect to the photographing optical axis O1, the lens 1 and the image sensor 3 are tilted with respect to the photographing optical axis O1 according to the tilt angle, and the entire subject SO is captured. It is possible to take an image that is in focus.

However, when the lens 1 is tilted with respect to the photographic optical axis O1 as shown in FIG. 1 and the image is taken, the magnification is different in each part of the image, so that, for example, as shown in FIG. When a subject SO is drawn, the image is reduced above the shooting optical axis O1, enlarged below the shooting optical axis O1, and further vertically if no magnification correction is performed. Therefore, it becomes difficult to accurately grasp the state of the subject SO.

Therefore, the computer 5 performs magnification correction on the image picked up by the image pickup device 3 by the method described below, and outputs the corrected image to the television monitor 6.

FIG. 3 is an explanatory view of the Scheimpflug optical system, in which the subject SO on the photographing optical axis O1, the lens 1, the image pickup device 3 are shown.
Is defined as points Pa, L, and Pb, and an intersection between the surface of the lens 1 and the extension line of the imaging surface of the image sensor 3 is defined as point P.
Distance PL, distance La between points Pa and L, distance Lb between points Pb and L
Then, the following equations (1) and (2) are established, and the relational expressions of the distances La and Lb
(3) is obtained. PL ＝ La ・ sin (φo −θa) / sin θa… (1) PL ＝ Lb ・ sin (φo + θb) ／ sin θb… (2) La ／ Lb ＝ (sin θa / sin θb) ・ {sin (φo + θb) / sin ( φo-θa)} (3) This La / Lb represents the magnification in the direction perpendicular to the paper surface.

FIG. 4 is an explanatory view showing the relationship between the minute line segment A'of the object SO and the minute line segment B'on the image pickup device 3, wherein each of the minute line segments A'and B'is taken as the photographic optical axis O1. Let A and B be minute line segments projected on a plane perpendicular to
The length yA 'and yB' of B'and the length y of the minute line segments A and B
The relationship between A and yB is approximately given by the following equations (4) and (5), assuming that they are sufficiently small. yA = yA '・ sin (φo−θa) (4) yB = yB' ・ sin (φo + θb) (5)

Therefore, by substituting these equations (4) and (5) into equation (3), the lengths yA 'and yB' of the minute line segments A'and B '.
Relationship, that is, the imaging magnification m is given by the following equation (6). m = yA '/ yB' = sin θa ・ sin (φ + θb) ・ sin (φ + θb) / {sinθb ・ sin (φ−θa) ・ sin (φ−θa)}… (6)

That is, the magnification m is determined by θa, θb determined by the Scheimpflug optical system and the angle φ depending on the position on the image pickup device 3. Therefore, the photographing magnification at each position on the computer 5 can be corrected using this magnification m. Actually, it is convenient to previously calculate the relationship between θa, θb, φ and the magnification m and store them as a table inside the computer 5. If it is necessary to accurately detect the distance between two points on the captured image, it is preferable to consider the magnification m as a continuous value and perform integral using Equation (6).

FIG. 5 shows another form for keeping the magnification constant.
It shows an optical system that is not a Scheimpflug optical system, and when the inclination angle of the subject SO is θ, the lens 1 and the image pickup device 3 are parallel to the subject SO in order to focus on all parts of the inclination angle. As described above, they are arranged at the inclination angle θ. By this arrangement, the magnification is made uniform at each position on the screen.

The difference in magnification between the tilt direction and the direction perpendicular thereto caused by the optical system may be corrected by, for example, an image calculation process or an optical system in which a cylindrical lens is appropriately combined.

FIG. 6 is a block diagram of a second embodiment in which the present invention is applied to an intracorneal photographing apparatus. An eye E to be inspected has a contact lens 7 provided with a light shielding plate 7a at the center thereof, and the eye E to be inspected. E, the lens 9 is arranged on the optical axis O2 of the photographing light source 8 arranged to face the contact lens 7, and the lens 1 having a variable inclination angle is arranged on the lower optical axis O3 parallel to the optical axis O2. The image pickup device 3 of the television camera 2 is arranged, the output of the image pickup device 3 is connected to the image memory 4, the output of the image memory 4 is connected to the computer 5, and the output of the computer 5 is connected to the television monitor 6. .. As in the first embodiment, the lens 1 and the image pickup element 3 form a Scheimpflug optical system.

The luminous flux from the photographing light source 8 travels on the optical axis O2,
The eye E is reflected by the side surface of the contact lens 7 worn through the lens 9 and guided into the cornea Ec. The light flux reflected on the surface of the cornea Ec is absorbed by the light shielding plate 7a,
A part of the light flux entering the inside is reflected by the inner surface Ec ′, is also reflected by the side surface of the contact lens 7, travels on the optical axis O3, and is imaged on the image pickup element 3 by the lens 1. This image is picked up by the television camera 2, stored in the image memory 4, and then magnification-corrected by the computer 5, so that the endothelial cells Mc are displayed on the television monitor 6. Also in the case of this embodiment, the image magnification correction is performed by using the equation (6) in the first embodiment, and the image is uniformly focused on each part on the TV monitor 6 and the image of uniform magnification is observed. Therefore, it is convenient for diagnosis.

FIG. 7 shows the configuration of the third embodiment, in which the eye E to be inspected is equipped with a contact lens 7'having a mirror surface 7b on the side of the cornea Ec at the central portion, and the lens is placed on the optical axis O4. Instead of the lens 1 connected to the drive unit 10 and the image pickup device 3 of the second embodiment, a film 12 of a film camera 11 is arranged, and a motor drive 13 for winding the film 12 is arranged.
Is connected to the lens drive unit 10, the film 12 is wound by the motor drive 13, and at the same time, the lens 1 is moved by the motor drive 13 via the lens drive unit 10 in the optical axis O4 direction. The configuration is similar to that of the second embodiment.

In this embodiment, the luminous flux from the photographing light source 8 travels on the optical axis O2, is reflected by the side surface of the contact lens 7'worn by the eye E through the lens 9, and is guided into the cornea Ec. It The light beam reflected on the surface of the cornea Ec is reflected on the mirror surface 7b of the contact lens 7 ', and a part of the light beam incident on the inside of the cornea Ec is reflected on the inner surface Ec' and reflected on the mirror surface 7c.
Repeatedly reflected with b, finally reflected by the side surface of the contact lens 7 ′, goes out of the contact lens 7 ′ and advances along the optical axis O 4, and the lens 1 causes the film 12
Is imaged.

In this embodiment, the motor drive 1
In synchronism with the movement of the film camera 11 at 3, the lens 1 is moved by the motor drive 13 in one direction along the optical axis O3, and is reflected by the respective portions R1, R2, R3 of the inner surface Ec '. The light flux is sequentially received by different portions F1, F2, F3 of the film 12 as shown in FIG. 8, and continuous recording is performed. If similar image processing is performed, the corner portions F1, F2, F3 of the film 12
Magnification correction can be performed on each of the endothelial cell images captured in (1) as in the first embodiment. In addition, each part
Repeated reflections at R1, R2, and R3 reduce the amount of light received by the film 12, but there is no problem if the amount of illumination light is increased.

In the conventional intracorneal photographing apparatus, since the reflection angle on the inner surface of the cornea is not so large, the separable range between the corneal surface and the inner surface is narrow and only the narrow area of the corneal endothelium can be photographed. Since it is possible to illuminate and photograph from a direction that is largely inclined to the surface, it is possible to photograph a wide range. Note that an optical system other than the Scheimpflug optical system shown in FIG. 5 may be used as the corneal endothelium imaging device.

[0023]

As described above, according to the eye image pickup apparatus of the present invention, it is possible to obtain an image of uniform magnification focused on the entire screen even if the inclination angle of the subject is large.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a difference in magnification depending on a part of an image captured by an image sensor.

FIG. 3 is an explanatory diagram of a Scheimpflug optical system.

FIG. 4 is an explanatory diagram of magnifications of minute line segments on a subject and an image sensor.

FIG. 5 is an explanatory diagram of an image pickup optical system that is not a Scheimpflug optical system.

FIG. 6 is a configuration diagram of a second embodiment.

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

FIG. 8 is an explanatory diagram of a recording state of a film.

[Explanation of symbols]

 1, 9 lens 2 TV camera 3 image sensor 4 image memory 5 computer 6 TV monitor 7, 7'contact lens 8 imaging light source 10 lens drive unit 12 film 13 motor drive

Claims (4)

[Claims] 1. An image pickup device for an image pickup device, wherein an image pickup device picks up a predetermined region of an eye to be examined as a subject, the lens optical axis being rotationally displaced from the image pickup optical axis in correspondence with an inclination of the subject from a reference plane. And an image pickup device for an eye, which has a unit for making a magnification constant at each position imaged through the image forming unit. 2. The eye imaging apparatus according to claim 1, wherein the predetermined portion of the eye to be inspected is a corneal endothelium. 3. The image forming unit is a Scheimpflug optical system, and the unit for making the magnification constant at each position to be imaged uses the correction coefficient determined by the arrangement of the Scheimpflug optical system to obtain the magnification. The eye image pickup apparatus according to claim 1, wherein the image pickup apparatus is a calculation unit that makes the value constant. 4. A plane perpendicular to the optical axis of said image forming means and a subject are parallel to each other, and a means for keeping the magnification constant at each imaged position is the image forming surface of said image forming means. 2. The eye image pickup device according to claim 1, wherein the image pickup device is arranged so as to be arranged so as to be arranged in a plane that is perpendicular to the optical axis of and in parallel with the subject.