JPH0381374B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an optical system for various eye examination apparatuses and optometry apparatuses such as fundus cameras, and particularly to an optical system for correcting diopter of an eye to be examined.

(Background of the Invention) As a diopter correction optical system for an optometrist, an internal focusing optical system with a simple configuration and less change in magnification due to diopter correction was disclosed in Japanese Patent Application Laid-Open No. 1983-1992 by the same applicant as the present application. It is known from the publication No.-91997. The internal focusing type diopter correction optical system disclosed herein further provides a second fundus image from the first fundus image formed by the objective lens.
The relay lens system for forming the fundus image is 2
Consisting of two positive lenses, the focal point of the positive lens on the patient's eye side matches the image-side focus of the objective lens, and the focal point of the composite system of both positive lenses is conjugate with the cornea of the patient's eye with respect to the objective lens. The lens was configured to match the position of the diaphragm located in the lens, and the diopter could be corrected by moving the rear positive lens along the optical axis. According to this,
It was possible to easily perform diopter correction with a small configuration without causing almost any change in the magnification of the second fundus image.

However, in the above known optical system,
The distance between the two relay lenses and the fundus image (film) is almost determined by the photographing angle of view of the objective lens and the screen size of the image plane, making it difficult to secure sufficient space on the image side. Therefore, it is necessary to insert various devices to provide various functions on the image side, such as a variable magnification optical system, a device for switching between two or more cameras, a side scope, and a finder optical system. The lack of optical path length has been an obstacle to increasing the functionality of optometry devices.

(Object of the Invention) The object of the present invention is to solve the above-mentioned drawbacks and to provide internal focusing diopter correction that can ensure a sufficient optical path length on the image side regardless of the shooting angle of view or image plane screen size. The objective is to provide an optical system.

(Summary of the Invention) A diopter correction optical system according to the present invention includes: an objective lens for forming an image of the fundus of an eye to be examined; an aperture diaphragm disposed at a position approximately conjugate with the pupil of the eye to be examined with respect to the objective lens; a relay lens system having a first positive lens and a second positive lens and disposed on the opposite side of the objective lens with respect to the aperture for re-imaging the fundus image formed by the objective lens; In the optometry apparatus, a negative lens is disposed between the diaphragm and the first positive lens, and the eye-side focus of the first positive lens is set to the image-side focus of a composite system of the objective lens and the negative lens. and a focal point on the eye side of the relay lens system formed by combining the first positive lens and the second positive lens is configured to match the position of the image of the aperture formed by the negative lens, and 2
A positive lens is provided movably on the optical axis with reference to the position arranged as described above, and diopter correction is performed by moving the second positive lens according to the diopter of the eye to be examined.

(Example) The present invention will be described below based on the configuration of the illustrated example.

FIG. 1 is a basic geometrical optical configuration diagram of a fundus camera using a diopter correction optical system according to the present invention. Light from the fundus R of the eye E to be examined passes through the pupil P and passes through the objective lens.
A first image I1 of the fundus is formed by Lo. This first fundus image I1 is formed at the back focal position of the objective lens Lo when the eye E to be examined is normal;
The position on the optical axis changes depending on the diopter of the eye to be examined, and the size also changes. The aperture Pc is located at a position conjugate with the pupil P of the eye to be examined with respect to the objective lens Lo, and is generally configured as an obliquely installed perforated reflector for supplying illumination light from an illumination optical system (not shown) to the fundus.
Alternatively, it is placed near this oblique reflecting mirror. The light flux from the first fundus image I1 is further apertured.
Pc, a second image I2 of the fundus is formed by a relay lens system LR consisting of a negative auxiliary objective lens La, a positive first lens L1, and a positive second lens L2 movable along the optical axis. Ru.

Here, the eye side focus of the first positive lens L1 is the image side focus of the composite system of the objective lens Lo and the negative auxiliary objective lens La, that is, the negative of the first fundus image I1 when the eye to be examined is an emmetropic eye. This corresponds to the position of the image I1' formed by the auxiliary objective lens La. Also, the first
Relay lens system LR consisting of a combination of a second positive lens
The focus on the subject's eye side matches the position of the image Pc' formed by the auxiliary objective lens La of the aperture Pc. That is, in this state, the relay lens system constitutes a telecentric system. Then, the second lens L2 moves along the optical axis based on the position in this state, thereby performing diopter correction.

Now, in the configuration shown in FIG. 1, if we assume that the image I' of the fundus image I formed by the negative auxiliary objective lens La is re-imaged by the first positive lens L1 and the second positive lens L2, then this The composition is the aforementioned Japanese Patent Application Publication No. 54
It can be explained in the same manner as the configuration disclosed in Japanese Patent No. -91997. In other words, the focal length of the composite system of objective lens Lo and negative auxiliary objective lens La is fo,
The projection magnification of the pupil P onto the aperture image Pc' by the composite system of the objective lens Lo and the negative auxiliary objective lens La is β, the focal length of the first positive lens L1 is f1, and the focal length of the second positive lens L2 is f2. , the first positive lens L1 and the second positive lens L1
The combined focal length with the positive lens L2 is f12, and the fundus image I by the auxiliary objective lens La is
From the 1' position, objective lens Lo and auxiliary objective lens La
Lo is the distance to the aperture image Pc' in the composite system with the aperture image Pc', l1 is the distance between this aperture image Pc' and the first positive lens, and l2 is the distance between the first positive lens L1 and the second positive lens L2, When the distance between the second positive lens L2 and the second fundus image I2 is 13, the following basic constitutive equation holds true as disclosed in Japanese Patent Laid-Open No. 54-91997.

f1=lo+l1=-β・fo+l1 f2=f1・f12/β・fo l2=f1−f1/β・fo(f12−f1) f3=f2 In this configuration, the negative auxiliary objective lens La Although the fundus image is slightly reduced,
In order to get closer to the relay lens system LR, the secondary image I2 of the fundus is enlarged, and it is also possible to ensure a large distance between the relay lens LR and the secondary image, that is, the focal length of the second lens. .

In order to set the final magnification of the secondary image to a predetermined value, the focal length and position of the negative lens La as an auxiliary objective lens can be arbitrarily selected, and the angle of view and screen size of the image plane can be selected arbitrarily. 2nd regardless of
The focal length of the positive lens can be increased, and a sufficient image-side space can be secured.

Note that it is also possible to enlarge the back focus of the relay lens system by placing the negative auxiliary objective lens La on the side of the eye to be examined of the aperture Pc.
As mentioned above, since the illumination light to the fundus is supplied from the vicinity of the aperture Pc toward the eye E to be examined, if an auxiliary objective lens is provided on the eye side of the aperture Pc, flare will occur here, so in practice, It is necessary to arrange the auxiliary objective lens La between the aperture Pc and the relay lens system.

FIG. 2 is a schematic configuration diagram of an example of a fundus camera configured based on the internal focusing optical system of the ophthalmoscopy apparatus according to the present invention, which can take pictures by alternately using two cameras, and also allows observation with a finder. . Among the members in FIG. 2, those having the same functions as those in FIG. 1 are given the same reference numerals. In the fundus camera shown in Figure 2, a variable magnification system LV consisting of a positive lens L3 and a negative lens L4 is removably installed on the image side of the relay lens LR. Indicates the state in which photography is performed. For this reason,
As shown in the photographing optical path shown in the figure, the photographing angle of view of the fundus is converted from θ shown in FIG. 1 to a smaller value θ'. A first swinging mirror M1 and a second swinging mirror M2 are arranged behind the variable power system LV. First swinging mirror M
The light beam reflected by the mirror M4 is condensed to form a second fundus image I1', and is then reflected by the eyepiece L7 through the field lens L6 disposed near this, and then by the examiner's eye Eo. be observed.
Further, the second oscillating mirror M2 is normally retracted to the position shown by the dotted line in the figure, and at this time the second fundus image I2 is formed on the film surface of the first camera. When the second oscillating mirror M2 is inserted at the position indicated by the solid line in the figure, a second fundus image I2'' is formed, and a third fundus image I3 is formed by the relay lens L5 via the mirror M3. It is formed on the film surface of the second camera.

In addition, in the fundus camera shown in Fig. 2, there is an auxiliary objective lens La and a first positive lens L of the relay lens system.
1, as shown by the dotted line, there is a strong diopter correction lens or a cylindrical lens L for astigmatism correction.
1' is provided in a removable manner. As described above, by moving the second positive lens L2 of the relay lens system along the optical axis, the diopter of the eye to be examined is corrected, and both the first and second cameras Also, with the finder, it is possible to photograph and observe a clear fundus image.

(Effects of the Invention) As described above, by using the internal focusing optical system of the optometry apparatus according to the present invention, a sufficient optical path length can be secured on the image side regardless of the shooting angle of view or the screen size of the image plane. It is possible to take pictures with a plurality of cameras and provide a viewfinder, etc., which greatly contributes to the multifunctionality of the optometry device.

[Brief explanation of drawings]

FIG. 1 is a basic geometrical optical configuration diagram of an internal focusing optical system of an optometry apparatus according to the present invention, and FIG. 2 is a schematic configuration diagram of an embodiment of the present invention. [Explanation of symbols of main parts], E... Eye to be examined, Lo
...Objective lens, La...Negative auxiliary objective lens,
LR...Relay lens system, L1...First positive lens,
L2...Second positive lens, Pc...Aperture, Pc'...Image of the aperture, I1...First fundus image.

Claims (1)

[Claims] 1. An objective lens for forming an image of the fundus of the eye to be examined, an aperture disposed at a position approximately conjugate with the pupil of the eye to be examined with respect to the objective lens, a first positive lens, a second positive lens, and the aperture. In an optometry apparatus having a relay lens system disposed on the opposite side to the objective lens, a negative lens is disposed between the aperture and the first positive lens, and a focal point of the first positive lens on the eye side to be examined is coincides with the image-side focal point of the composite system of the objective lens and the negative lens, and the first
A relay lens system consisting of a positive lens and the second positive lens is configured so that the focal point on the subject's eye side coincides with the position of the image of the diaphragm formed by the negative lens, and the second positive lens is configured as described above. 1. An internal focusing optical system for an optometry apparatus, characterized in that the internal focusing optical system is movable on an optical axis with reference to a disposed position.