JPS61288823A - Apparatus for measuring eye refraction - 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 [Industrial Field of Application] The present invention relates to an eye refraction measuring device used in eye clinics, mirror shops, etc. to measure eye refractive power.

[Prior Art] Various refractometers have been used as eye refractive power measuring devices.Generally, when measuring eye refractive power, a predetermined index is projected onto the fundus of the eye to be examined. Measured values are obtained by receiving the reflected image with a detector and analyzing the data.

By the way, by measuring the refractive power in the three radial directions, it is possible to know the refractive power of all eyes, so recently we projected three patterns at different positions on the fundus, and the reflected light flux was approximately An apparatus is used in which the eye is taken out from a symmetrical position, guided onto a three-line sensor array, and the eye refractive power is determined from the position on the sensor array. However, although this method does not have any problems with the accuracy of the measured values, it has the drawback that it requires three line sensor arrays, which makes the structure a little complicated and the cost is high. .

[Object of the Invention] An object of the present invention is to provide an ocular refraction measuring device that eliminates the above-mentioned drawbacks, has a simple structure, is inexpensive, and can provide good measured values.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide a projection means for projecting each index in at least three radial directions onto the fundus of the eye using three light beams from a position away from the pupil center of the eye to be examined. a first light guiding means for extracting reflected light beams from positions substantially symmetrical with respect to the pupil center of each of the light beams; This is an eye refraction measuring device characterized by having a second light guiding means for converting three radial directions into a single radial direction for guiding onto a sensor array.

[Embodiments of the invention] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 is an optical layout diagram. On an optical axis 0 connecting a light source 1 such as an LED and the fundus Er of the eye E to be examined, there are polarizing prisms 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, and 4 are arranged on the optical axis 0 which connects a light source 1 such as an LED and the fundus Er of the eye E to be examined. A three/) plate 3, lens 4, aperture 5, lens 6, and objective lens 7 are arranged, and a half mirror 8 is arranged in the lower half of the light beam from the optical axis 01 between the lens 6 and the objective lens 7. There is. On the optical axis 02 reflected by this half mirror 8, there is a lens 9, an aperture diaphragm 10. A radial rotation/deviation prism 11 and a linear photosensor array 12 are arranged.

As shown in FIG. 2, the polarizing prism 2 is composed of three wedge prisms 2a, 2b, and 2C, and the light source 1
The light beams emitted from the wedge prisms 2a, 2b, 2c
It is divided into three parts by. FIG. 3 shows three slits 3a, 3b, and 3c of the slit plate 3, and the light beam divided into three by the polarizing prism 2 passes through each slit 7) 3a, 3b, and 3C of the slit plate 3, and passes through the lens 4. The image is formed on the aperture stop 5 by this.

In Figure 4, the opening is from the center to the upper half of the aperture stop 5)3
The light beams emitted from a, 3b, and 3c are transmitted through the corresponding apertures 5a.
, 5b, 5C, and is re-imaged by the objective lens 7 onto the pupil Hp of the eye E to be examined. It is arranged so as to be conjugate to Er.

The light beam reflected from the fundus Er is reflected by a half mirror 8 that reflects the light beam below the optical axis O1, and enters the aperture stop 10 via the lens 9. FIG. 5 shows a front view of the aperture stop 10, with three apertures 1 located at positions conjugate to the aperture stop 5.
It has 0a, 1Ob, and 10c. Each of these openings 1
The light beams that have passed through 0a, 10b, and 10c are rotationally deflected by a radial rotation/deflection prism 11 and guided onto a linear photosensor array 12 located at a position conjugate with the slit plate 3. In this way, corneal reflection can be avoided by sending light from one half of the pupil Ep to the fundus Er using the aperture diaphragm 5 and measuring the luminous flux emitted from the other half of the pupil Ep using the aperture diaphragm 10.

The fi W rotation/deflection prism 11 consists of three small prisms lla, llb, and 1lc (lla and llc are not shown) corresponding to the light beams passing through the apertures 10a, iob, and 10c of the aperture stop 10, and the aperture 10b. A small prism llb corresponding to the above is shown in FIG. The radial rotation zero deviation prism 11 has a radial rotation function and a deflection function, and the radial rotation function is performed by this small prism llb. In other words, when the light beam passing through the small prism llb is viewed within the plane of the paper in FIG. 90 around the axis
'When rotated, the direction of the image does not change within the plane of the paper, but is reversed within the plane perpendicular to the plane of the paper, resulting in the image being rotated 1800 times. This method utilizes the fact that when such a small prism llb is rotated around the optical axis, the image rotates around the same axis by twice the rotation angle. In addition, the deflection function is performed using a small prism l.
This can be achieved by appropriately setting the inclination of the incident/exit surface of lb.

In this way, the light flux passing through the aperture lOb is transmitted through the small prism l
The openings 10'a, 10 are rotationally displaced by the linear photosensor array 12 at predetermined positions on the linear photosensor array 12.
b, The passing light flux of 10C is imaged. Note that for one radius line, if rotational deviation is not performed, only two small prisms are required.

FIG. 7 shows a reflected image on the linear photosensor array 12 arranged at a predetermined position by the radial rotation/deviation prism 11, and the slit image 3A is the slit 3a, apertures 5a, 10a.
The slit image 3B is an image of the light flux that has passed through the slit 3b, the apertures 5b and 10b, and the slit image 3C is an image of the light flux that has passed through the slit 3C1 and the aperture 5C110c.

By the way, when the standard emmetropic eye is the eye to be examined, by appropriately selecting the rotation angle and the incident/exit surface angle of the radial rotation/deviation prism 11, the reflected image on the linear photosensor array 12 can be formed. It can be placed at predetermined positions with intervals. In this way, the deflection prism 11 during radial rotation
When the following conditions are set and another eye E is placed, the position of the reflected image moves according to the difference in refractive power with the emmetropic eye in each radial direction, so each reflected image 3A, 3B, 3C The position of is the data for knowing each refractive power. That is, the refraction value in the direction of the aperture 5a and lOa is determined at the position of the 1 reflected image 3A, and the refraction value of the images 3B and 3C
Then, the openings 5b, 10b direction, and opening 5C110c, respectively.
The refraction value of the direction will be found.

By the way, since the refraction value change in the radial direction of the eye is considered to be sinusoidal, if the refraction values in the three radial directions are known, the refraction values in the other radial directions can also be calculated, and the refraction value of the subject @E, That is, the spherical power, the astigmatism number, and the astigmatism angle can be calculated.

FIG. 8 shows the light source of the second embodiment, and the first
In place of the light source l in the embodiment, three light sources 13a, 13b,
13c are arranged and are turned on in sequence.

In this embodiment, three light sources 13a, 13b, 13
Because c.

The polarizing prism 2 that splits the luminous flux into three directions may be removed, but other than the polarizing prism 2, the radial rotation ψ deviation prism 1 is used.
The second embodiment has the same structure as the first embodiment, except that the angle of incidence and exit plane 1 and the length of the linear photosensor array 12 are changed.

The three light sources 13a, 13b, and 13c are turned on in sequence,
Three slits 3a, 3b, 3 of the slit plate 3, respectively.
c, and three slit images are sequentially formed on the linear photosensor array 12 in the same manner as in the first embodiment. In this way, since the three slit images are formed on the linear photosensor array 12 not simultaneously but sequentially, there is no need to shift the positions of the three slit images as in the first embodiment. 3-light TX13 a, 1 for emmetropic eyes
Adjust the entrance/exit surface angle of the radial rotation/deviation prism 11 so that when 3b and 13c are sequentially turned on, the reflected images in the three radial directions are formed at the same position on the linear photosensor array 12. If this is done, the refractive power in the three radial directions can be determined based on the deviation of the reflected image in the three radial directions from the reference position when the eye E is placed.

In this second embodiment, the number of light sources must be increased compared to the first embodiment, but in return, the sensor array 12
Since the upper slit image can be reduced to one, the length of the sensor array can be shortened.

As the aperture stop 5, three apertures 5a, 5b, and 5c are arranged at equal intervals as shown in FIG.

As shown in FIG. 10, the aperture diaphragm lO is
b, 5c and an aperture 1 provided at a symmetrical position with respect to the optical axis O1.
0a, 10b, loc, but in this case it is preferable to use a perforated mirror instead of the half mirror 8.

[Effects of the Invention] As explained above, the ocular refraction measuring device according to the present invention has a prism having a radial rotation function and a deflection function installed in the light beam of the fundus reflected light, thereby converting one reflected light receiving surface into one reflected light receiving surface. It can be made into a linear photo sensor array, which simplifies the structure and improves operability. By shortening the required length of the linear photo sensor array, it is possible to perform accurate measurements with inexpensive equipment. It becomes possible.

[Brief explanation of drawings]

The drawings show an embodiment of the eye refraction measuring device according to the present invention, in which Fig. 1 is an optical layout diagram, Fig. 2 is a front view of a polarizing prism, Fig. 3 is a front view of a slit plate, and Fig. 4 is a front view of a polarizing prism. The figure shows a front view of an aperture stop with three apertures in the upper half, Figure 5 is a front view of an aperture stop with three apertures in the lower half, and Figure 6 shows the light flux passing through the image rotation prism. Explanatory diagram of the state of
The figure shows the distribution of slit images on a linear photosensor array. FIG. 8 is a layout diagram of three light sources according to another embodiment, and FIGS. 9 and 10 are front views of an aperture stop according to another embodiment. 1 and 13 are light sources, 2 is a polarizing prism, 3 is a slit plate, 5 and 10 are aperture stops, 8 is a half mirror, 111 is a radial rotation function prism, and 12 is a linear photosensor array. Patent applicant Canon Co., Ltd. Figure 1

Claims (1)

[Claims] 1. At least 3 points from a position away from the pupil center of the eye to be examined.
a projection means for projecting each index in the radial direction onto the fundus of the eye using three light beams; a first light guide means for taking out the reflected light beam from a position approximately symmetrical with respect to the pupil center of each of the light beams; and a second light guiding means for converting three radial directions into a single radial direction for guiding each of the reflected light beams guided by the light guiding means onto one linear photosensor array. An eye refraction measurement device. 2. The projection means includes a light source, a polarizing prism consisting of three wedge prisms, a slit plate having three slits, and a slit plate located at a position conjugate to the pupil of the eye to be examined, and three wedge prisms located away from the center. The eye refraction measuring device according to claim 1, further comprising a first diaphragm having an aperture. 3. The first light guiding means includes a half mirror that reflects a light beam on one half of the optical axis, and a second diaphragm having an opening at a position symmetrical to the first diaphragm. 1st
The ocular refraction measuring device described in Section 1. 4. The eye refraction measuring device according to claim 1, wherein the second light guiding means has a meridian rotation and deflection function for at least two meridians. 5. The ocular refraction measuring device according to claim 2, wherein the light source is one, and three fundus reflection images are simultaneously obtained on the linear photosensor array. 6. Claim 2, wherein the number of light sources is three, and by sequentially lighting up the three light sources, fundus reflection images are sequentially obtained one by one on the linear photosensor array. The ocular refraction measuring device described in .