JPS6018153A - Eye refraction measuring instrument - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ocular refractometer suitable for use in eye clinics, opticians, and the like.

Various types of conventional eye refractometers are used, but they generally have mechanically movable parts, making it difficult to visualize the structure.
There is a problem in that sufficient accuracy cannot be expected.

An object of the present invention is to provide an eye refraction measuring instrument that does not use conventional mechanical movable parts, has a simple structure, is low in cost, and has high accuracy. comprising a projection optical system that sequentially projects a pattern onto the fundus of the eye via at least three different positions, and a light receiving optical system that receives reflected light from the fundus with a position detection element,
This method is characterized in that an eye refraction value is calculated from two-dimensional positional information of the pattern image on the fundus.

The present invention will be explained in detail below based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which the fundus Ef of the eye E to be examined is
In a projection optical system for projecting a pattern onto a light source, three light sources 1a and 1b are placed at symmetrical positions with respect to the optical axis as shown in FIG.
After passing through a fundus conjugate diaphragm 4 having a circular opening pattern 40 shown in FIG. 3, a relay lens 5, and a pupil conjugate diaphragm 6 having three apertures 6a, 6b, 6c as shown in FIG. The light is deflected by the mirror 7 and reaches the fundus Ef from three different locations of the pupil Ep via the objective lens 8, and an open pattern 40 is projected onto the fundus Ef. on the other hand,
In the light-receiving optical system, the reflected light reflected by the fundus Ef passes through the objective lens 8 and the perforated mirror 7, and enters the aperture 90 in the center.
The light passes through a pupil conjugate aperture 9 and a relay lens 10, and is received by a two-dimensional position detection element 11 made of, for example, a semiconductor. Here, light'IQ 1 a, l
b, IC has an aperture of 6.9 and is conjugate with the pupil Ep, and the aperture 4 is placed at the back focal position of the objective lens 8, and is in a position conjugate with the fundus Ef of the emmetropic eye E and the detection element 11, respectively. It is said to be related.

In this embodiment, the image light of the opening pattern 40 is made to enter the subject's eye E from the periphery of the pupil Ep by the projection optical system, and the reflected light from the fundus Ef is extracted from the center of the pupil Ep by the light receiving optical system. Dimensional position detection: Light is received by the element 11, and pattern images P obtained on the detection element 11 are illustrated in FIGS. 6 to 9.

That is, when the fundus Ef is in the position of emmetropia, the pupil Ep
Since the lights that are sequentially incident from three points on the periphery of the eye all coincide at the fundus Ef, one pattern image P is formed on the detection element 11 as shown in FIG.

In addition, in the case of hyperopia, the light incident from the upper part of the pupil Ep, that is, the aperture 6a shown in FIG. Then, there are three pattern images Pa, Pb, and Pc, and the amount of blur of the pattern images Pa, Pb, and Pc increases.

Conversely, in the case of myopia, as shown in Figure 8, 3
The point pattern images Pa, Pb, and Pc are obtained, and their positions are symmetrical to those in the case of farsightedness. Furthermore, FIG. 9 shows a pattern image P of an astigmatic eye with farsightedness in the vertical direction and emmetropia in the horizontal direction. In this case, the pattern images Pb and Pc from the apertures 6b and 6C of the aperture 9 overlap on the fundus Ef, and the pattern images Pa from the aperture 6a do not overlap, but the pattern images Pa, Pb,
P-c will be somewhat elliptically blurred.

The two-dimensional position detecting element 11 may be a sensor array such as a so-called CCD, but it is preferable to use a semi-central position detecting element whose position information can be determined in an analog manner by the voltage relationship between both ends.

In this way, by sequentially lighting up the light sources 1'a, lb, and 1c, the positions of the pattern images Pa, Pb, and Pc on the respective detection elements 11 are detected, and the refractive state of the eye E to be examined is known. Can be done. In order to calculate the spherical power, astigmatic power, and astigmatic angle that indicate this refraction value, there are three unknowns, so it is necessary to make measurements by entering light from at least three locations. Note that errors due to the distance between the objective lens 8 and the eye E to be examined can be eliminated by making the input light from the open rotor pattern 40 parallel to the optical axis.

10 to 12M show a second embodiment of the present invention, in which the open ropacoon 41 of the fundus conjugate diaphragm 4 is square and blurred as shown in FIG. 1O, and the two-dimensional position detection element 11 is as shown in FIG. 11. As shown, a four-element photodetector consisting of four photodiodes lla, 11b, lie, and lid arranged in a ``ta'' shape is used. FIG. 812 shows a state in which pattern images Pa, Pb, and Pc are incident on the detection element 11.

In this case, as in the first embodiment, if the eye is emmetropic, the square pattern images Pa', Pb, and Pc overlap at the center, and the same signal is output from each of the diodes lla to lid. However, the pattern images Pa, Pb, and Pc are the first
As shown in Figure 2, if the output signal is off-center, there will be a magnitude relationship between the output signals of the diodes lla to lid.
This allows the positions of the pattern images Pa, Pb, and Pc to be detected.

FIG. 13 shows a third embodiment of the present invention, in which opening patterns 12a and 12b of the fundus conjugate diaphragm 12, which corresponds to the diaphragm 4 in FIG. 1, are mutually arranged as shown in FIG. It consists of two slits that are at right angles. Further, for detection, two one-dimensional position detector elements 13 and 14 are arranged so that their extension lines are perpendicular to each other. These position sensing elements 13, 14 may be digital or analog one-dimensional position sensing devices using array elements. Immediately in front of the detection element 13.14, a cylindrical lens 15.16 having a generatrix in the length direction of the detection element 13.14 is added in order to focus light in a direction unrelated to measurement.

FIG. 15 shows the pattern images Pa and Pb formed on the position detection elements 13 and 14, and by numerically determining these positions, the same measurements as in the previous example can be avoided. obtain.

As described above, the ocular refractometer according to the present invention has no mechanically movable parts, and the overall structure can be easily miniaturized.
There are advantages to rapid measurement. Furthermore, since errors caused by the distance between the eye to be examined and the objective lens can be removed by making the incident light from the open rotor pattern parallel to the optical axis, it has the advantage of high measurement accuracy.

[Brief explanation of the drawing]

The drawings show an embodiment of the ocular refractometer according to the present invention, and the first
The figure is a diagram of the failure of the first embodiment, Figure 2 is a layout diagram of the light source, Figures 3 to 5 are front views of the aperture, and Figures 6 to 9 are explanations of pattern images on the detection element. 10 is a front view of the fundus conjugate aperture of the second embodiment, FIG.
14 is a front view of a fundus conjugate aperture, and FIG. 15 is an explanatory diagram of a pattern image on a detection element. 1a, lb, and IQ are light sources; 4 is a fundus conjugate aperture; 6.
9.12 is the pupil conjugate aperture, 40.41.6a, 6b, 6c
, 12a, l 2. b is an open rotor pattern, 7 is a mirror with a hole, 8 is an objective lens, 11 is a two-dimensional position detection element,
lla, llb, 11c, lid are photodiodes,
13.14 is a one-dimensional position detection element, 15.16 is a cylindrical lens, E is the eye to be examined, EP is the pupil, Ef is the fundus, and Pa, Pb, and Pc are pattern images. Patent applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] 1. A projection optical system that sequentially projects a pattern onto the fundus of the eye via at least three different positions of the pupil of the eye to be examined, and a position detection element that receives reflected light from the eye and the fundus. 1. An eye refraction measuring instrument comprising a light receiving optical system, and calculating an eye refraction value from two-dimensional positional information of the pattern image on the fundus. 2. The ocular refractometer according to claim 1, wherein the projection optical system sequentially projects a pattern onto the fundus of the eye using three light sources that are sequentially turned on. 3. The pattern is projected from three points on the periphery of the pupil of the eye to be examined, and the reflected light from the fundus is extracted from the center of the pupil and received by a two-dimensional position detection element. The ocular refraction measuring device described in Section 1. 4. The pattern has a square shape, the pattern is projected from three points on the periphery of the pupil, and the reflected light from the fundus is extracted from the center of the pupil and received by a detection element having four elements arranged in a plane. An eye refractometer according to claim 1, wherein the ocular refractometer is configured to: 5. The pattern consists of two rectangular slits at right angles to each other, the pattern is projected from three points on the periphery of the pupil, and the reflected light from the fundus is extracted from the center of the pupil. The eye refraction measuring device according to claim 1, wherein light is received by a plurality of partial element 1δ detection elements. 6. The eye refractometer according to claim 5, wherein a silitoric lens having a generatrix in the direction of the detection position is disposed in front of the two one-dimensional position detection elements.