JPH07265267A - Eye measuring device - Google Patents

Abstract

PURPOSE:To measure eye refraction with high accuracy by guiding the fundus reflected light to a two-dimensional light position sensor via a light flux aperture arranged conjunctively to the pupil of an eye under inspection in optical paths split by a light splitting member, and determining the eye refraction value based on the output of the two-dimensional light position sensor. CONSTITUTION:The wavelength light from a refraction measuring light source 23 passes through a dichromic mirror 10 and is reflected on a dichroic mirror 17, and the light source 23 is image-formed near the rear side focal point of an objective lens 1. The light flux reflected on the fundus Er of an eye E under inspection is reflected on a perforated mirror 20, and it is projected on a two-dimensional array sensor 19 via a lens 25 through the openings of a six-hole aperture 24. The passed light fluxes from the openings 24a, 24d; 24b, 24e; 24c, 24f of the six-hole aperture 24 are projected on ruled lines AD, BE, CF on the sensor 19 via a cylinder lens 18, and the refracting power in each ruled line direction is measured based on the interval between two light spots on each ruled line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eye measuring device used for measuring an eye refraction value.

[0002]

2. Description of the Related Art Conventionally, there has been a demand for an eye measuring apparatus having a downsized structure, and in particular, an apparatus capable of performing highly accurate eye refraction measurement while achieving downsizing is desired.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an eye measuring device capable of highly accurate eye refraction measurement without downgrading the measurement accuracy while reducing the size of the structure.

[0004]

An eye measuring apparatus according to the present invention for achieving the above object comprises a light splitting member, and a projection system for projecting a point light beam through the light splitting member onto the fundus of the eye to be examined. A light beam diaphragm arranged at a position substantially conjugate with the subject's eye pupil in the optical path branched by the light splitting member, one two-dimensional optical position sensor, and a two-dimensional light beam from the fundus of the subject's eye projected as a point-like light beam by the projection system. It has a light receiving system for guiding the reflected light to the two-dimensional light position sensor through the light splitting member and the light beam diaphragm, and obtains an eye refraction value based on the position of the light beam detected by the two-dimensional light position sensor. It is characterized by

[0005]

In the eye measuring device having the above-described structure, the point light beam is projected onto the fundus of the eye to be examined through the light splitting member, and the fundus reflected light is conjugated with the pupil of the eye to be examined in the optical path split by the light splitting member. The light is guided to the two-dimensional optical position sensor through the light beam diaphragm disposed at, and the eye refraction value is obtained based on the light beam position on the two-dimensional optical position sensor.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. For example, FIG. 1 shows a first example for understanding the present invention, in which an objective lens 1 is arranged facing an eye E to be inspected,
Behind this objective lens 1, a diaphragm 2, a light splitting member 3,
4, a cylindrical lens 5a, a one-dimensional sensor array 6a including a CCD and the like are arranged. Further, the cylindrical lens 5b and the one-dimensional sensor array 6b are arranged in the reflecting direction of the light dividing member 3, and the cylindrical lens 5c and the one-dimensional sensor array 6c are arranged in the reflecting direction of the light dividing member 4. Further, as shown in FIG. 2 with the optical axis O as the center, six measurement light sources 7a to 7f are arranged at equal angles and equal distances. A point light source such as a light emitting diode is used as each of the measurement light sources 7a to 7f, and at least two point light sources are arranged in each of the three radial directions. The measurement light sources 7a and 7d, 7b and 7e, 7c and 7f are each radial line. They are arranged in the AD, BE, and CF directions. However,
When the alignment between the cornea Ec of the eye E to be inspected and the apparatus is matched, one light source 7 may be provided for each radial line.

The generatrix direction of the cylindrical lens 5a and the array arrangement direction of the one-dimensional array sensor 6a are in the radial line AD direction,
The cylindrical lens 5a functions to condense the light beam on the one-dimensional array sensor 6a. Similarly, the generatrix direction of the other cylindrical lens 5b and the arrangement direction of the one-dimensional array sensor 6b,
And the direction of the generatrix of the cylindrical lens 5c and the one-dimensional array sensor 6
The arrangement directions of c are the radial directions BE and CE, respectively. Further, the diaphragm 2 and each one-dimensional array sensor 7 are conjugated by each cylindrical lens 6 in a direction perpendicular to the generatrix of each cylindrical lens 6.

In this example, the measurement light sources 7a and 7d form virtual images 7A 'and 7D' on the cornea Ec of the eye E to be inspected, and these images 7A 'and 7D' are formed by the objective lens 1 and the diaphragm 2 and light. It is projected on the one-dimensional array sensor 6a through the dividing members 3 and 4 and the cylindrical lens 5a. Similarly, the images of the measurement light sources 7b and 7e are reflected by the light splitting member 3, pass through the cylindrical lens 5b, and are projected on the one-dimensional array sensor 6b. Further, the images of the measurement light sources 7c and 7f are also reflected by the light splitting member 4, pass through the cylindrical lens 5c, and are projected onto the one-dimensional array sensor 6c. In this case, it is desirable to arrange the diaphragm 2 in the vicinity of the rear focal position of the objective lens 1 in order to make it difficult to receive an error due to the working distance.

FIG. 3 is an explanatory view of the cylindrical lens 5a and the one-dimensional array sensor 6a. Since the virtual images 7A 'and 7D' are images 7A "and 7D" on the one-dimensional array sensor 6a, their positions can be obtained. Good. The corneal shape such as the radius of curvature of the cornea and the corneal astigmatism can be measured from the positions on the three radial lines thus obtained.

Since the cornea Ec generally has astigmatism, it is assumed to be a spheroid. First, when there is no center of curvature of the cornea Ec on the optical axis O, the two images on the one-dimensional array sensor 7 are asymmetric with respect to the center. That is, the two images 7A ″, 7 shown in FIG.
The center coordinates of D "represent the eccentricity in the direction of the radial line AD, and represent the eccentricity in the two directions. Therefore, the two-dimensional center coordinates can measure the two-dimensional eccentricity.

Further, even if there is eccentricity, the image interval remains unchanged, and this interval is inversely proportional to the sum of the reflective spherical refractive power of the cornea Ec and its radial component of the reflective cylindrical refractive power. From this relationship, three relational expressions including the three radial lines will be obtained. Since the unknowns are the spherical power, the cylindrical power, and the angle, the spherical power, etc. should be calculated from these simultaneous equations. Is possible.

FIG. 4 shows a second example for understanding the present invention, where the same numbers as in FIG. 1 represent the same members.
In this embodiment, a cylindrical lens plate 8 is used instead of using the light splitting members 3 and 4 of FIG. As shown in FIG. 5, the cylindrical lens plate 8 has three radial lines AD, BE, CF.
Cylindrical lenses 8a to 8 each having a generatrix in the direction of
6 and has a wedge shape as shown in FIG. 6 and has a function of refracting the light beam in the optical axis O direction. As the optical position sensor, a two-dimensional area array sensor 9 such as a photographing CCD as shown in FIG. 7 is used.

An image 7A "is drawn on the lines of the radial lines AD, BE, CF.
Since 7D "and the like are projected, these images 7A" and 7D "
The corneal shape can be measured from the interval of as described above. The cylindrical lens plate 8 is arranged at positions where the light beams from the six light source images pass through the diaphragm 2 and are separated, and similarly, the diaphragm 2 and the area array sensor 9 are conjugated in the direction perpendicular to the generatrix. The deflecting action of the wedge-shaped cylindrical lenses 8a to 8f is useful for allowing the light flux of the enlarged image to enter the area sensor array 9 in order to improve the accuracy.

FIG. 8 shows an embodiment of the present invention. This embodiment has both the functions of eye refraction measurement and corneal shape measurement, and shares the light receiving portion. First, regarding the corneal shape measuring system, the measurement light sources 7a to 7d, which are point light sources, are arranged in the same manner as in the case of FIG. 1, but the dichroic mirror 10 is obliquely installed behind the objective lens 1 and its reflection is performed. A lens 11, a diaphragm 12, a cylindrical lens plate 13, and a lens 1 are provided on the side optical axis.
4 are sequentially arranged. A lens 16, a dichroic mirror 17, a cylindrical lens plate 18, and a two-dimensional array sensor 19 are sequentially arranged behind the lens 14 via a total reflection mirror 15 for optical path conversion.

Here, the diaphragm 12 is placed near the rear focal position of the optical system including the objective lens 1 and the lens 11, and the cylindrical lens plate 13 is the same as the cylindrical lens plate 8 shown in FIGS. With the same configuration, the deflection directions by the wedge shape are AD, BE, and CF directions. Lens 1
Reference numeral 4 is a field lens, on which a corneal image is projected, and the lens 16 is used to project a two-dimensional array sensor 19 on this surface.
It is designed to project on top. The dichroic mirror 17 has a characteristic of transmitting wavelength light from the measurement light sources 7a to 7d and the like. In addition, six measurement light sources 7a to 7
f will light up one by one. As shown in FIG. 9, the cylindrical lens plate 18 is composed of three cylindrical lenses 18a, 18b, and 18c having a generatrix in the measurement radial direction, is located near the two-dimensional array sensor 19, and collects light in the direction perpendicular to the generatrix. It has the function of shining.

The image projected on the two-dimensional array sensor 19 is, for example, as shown in FIG. 10, and since the light beam is projected on a specific radial line indicated by the same radial lines AD, BE, and CF as the measuring radial line, It is possible to measure the corneal shape from the distance between two light spots on these radial lines.

Next, regarding the eye refraction measurement system, the perforated mirror 20 behind the dichroic mirror 10 on the optical axis O is used.
Then, a diaphragm 21, a lens 22 and a refraction measuring light source 23 are sequentially arranged, and a 6-hole diaphragm 24, a lens 25, a prism plate 26 and a dichroic mirror 17 are arranged on the optical axis of the reflection side of the perforated mirror 20. ing.

The wavelength light from the refraction measuring light source 23 passes through the dichroic mirror 10 and is reflected by the dichroic mirror 17. Refraction measuring light source 23
A point light source such as a light emitting diode is used for this, and it is desirable that this is arranged conjugate with the fundus Er of the eye E to be emmetropic. The refraction measuring light source 23 is imaged by the lens 22 near the rear focus of the objective lens 1. The diaphragm 21 has an opening at the center and is substantially conjugate with the pupil of the eye E to be examined. Also, 6
As shown in FIG. 11, the aperture stop 24 has six openings 24a to 24f that are equidistant and equiangular with respect to the optical axis, and are similarly arranged conjugate to the pupil. Prism plate 26
Is the six wedge prisms 26a to 26f as shown in FIG.
The two-dimensional array sensor 19 is conjugate with the refraction measuring light source 23 when the refracting powers of the cylindrical lenses 18a, 18b, and 18c are not taken into consideration.

The luminous flux reflected from the fundus Er of the eye E to be examined is reflected by the perforated mirror 20, passes through the opening of the 6-hole diaphragm 24, and is projected onto the two-dimensional array sensor 19 by the lens 25. In this case, since the 6-hole diaphragm 24 is conjugate to the pupil,
The reflected light can be taken out from six places around the pupil in the direction of the three-diameter line.

If the prism plate 26 is not provided, the six light beams from the fundus Er of the eye E to be emmetropic will be concentrated at one point in the center, but the prism plate 26 independently measures the positions of these six light beams. It separates on the two-dimensional array sensor 19 so that it can be deflected in each direction of the cylindrical lenses 18a, 18b, 18c. For example, the light flux emitted from the openings 24a and 24d of the 6-hole diaphragm 2a reaches the radial line AD on the two-dimensional array sensor 19 through the cylindrical lens 18a. Light fluxes from the openings 24b and 24e of the 6-hole diaphragm 24 pass through the cylindrical lens 18b and reach the radial line BE,
Similarly, since the light fluxes from the openings 24c and 24f reach the radial lines CF, the refracting power in each radial direction can be measured from the interval between the two light spots on each radial line. That is, if the refractive power in the radial direction is obtained and the change in the radial direction is assumed to be sinusoidal,
An eye refraction value composed of a spherical power, an astigmatic degree, and an astigmatic angle can be obtained.

Although the above-mentioned embodiment shows the case of the three-diameter wire, it goes without saying that the same is applicable to the three-diameter wire or more. Further, although the case where the array position sensor is used as the optical position sensor has been described, an analog type optical position sensor such as a semiconductor optical position detector (position detector) may be used.

[0022]

As described above, the eye measuring apparatus according to the present invention can be miniaturized by the structure in which the luminous flux position is detected by one two-dimensional optical position sensor for the fundus reflected light.
The point-like light flux makes it difficult for the light flux position on the light receiving surface to be affected by the unevenness of the fundus, and the light flux diaphragm located at a position approximately conjugate to the pupil more effectively removes harmful light such as the anterior eye part and possibly glasses. By doing so, it is possible to prevent an error that is likely to occur due to the spread of the light receiving surface, and to realize high-precision measurement without deteriorating the measurement accuracy while reducing the size.

[Brief description of drawings]

FIG. 1 is an optical configuration diagram of a first example.

FIG. 2 is a front view of an arrangement example of measurement light sources.

FIG. 3 is an explanatory diagram of a relationship between a cylindrical lens and a one-dimensional array sensor.

FIG. 4 is a configuration diagram of a second example.

FIG. 5 is a front view of a cylindrical lens plate.

FIG. 6 is a side view.

FIG. 7 is an explanatory diagram of light spots on the area array sensor.

FIG. 8 is a configuration diagram of an embodiment.

FIG. 9 is a front view of a cylindrical lens plate.

FIG. 10 is an explanatory diagram of a relationship between an array sensor and a light spot.

FIG. 11 is a front view of a 6-hole diaphragm.

FIG. 12 is a front view of a prism plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 12,21 Stopper 7a-7f Measurement light source 13,18 Cylindrical lens plate 19 Two-dimensional area array sensor 10,17 Dichroic mirror 20 Perforated mirror 23 Refraction measurement light source 24 6-hole stop

Claims (1)

[Claims] 1. A light splitting member, a projection system for projecting a point-like light flux onto the fundus of the eye to be examined via the light splitting member, and an optical path branched by the light splitting member at a position substantially conjugate to the pupil of the eye to be examined. The arranged light beam diaphragm, one two-dimensional optical position sensor,
The two-dimensional light position has a light receiving system that guides the reflected light from the fundus of the subject's eye that is projected as a point-like light beam by the projection system to the two-dimensional light position sensor via the light splitting member and the light beam diaphragm. An eye measuring device characterized by obtaining an eye refraction value based on a position of a light beam detected by a sensor.