JPH06245909A - Eye refractometer - Google Patents

Abstract

(57) [Summary] [Purpose] To make it possible to obtain an accurate eye refraction value with a simple structure, and also to cope with small pupils and opaque eyes. A light flux from a point light source 1 is projected onto a fundus Er of an eye E through a lens 2, a diaphragm 3 having a central aperture at a pupil conjugate position, a movable mirror 4, a half mirror 5 and an objective lens 6, and the fundus reflected light flux Is configured to be received by an objective lens 6, a half mirror 5, a diaphragm conjugate with a pupil Ep, an inverted conical prism 8 and a lens 9 and an optical position sensor 10 conjugated with an emmetropic fundus, and a ring on the optical position sensor 10. The eye refraction value is obtained by analyzing the position and shape of the light flux.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eye refractometer used for measuring an eye refraction value in an ophthalmology clinic or an eyeglass store.

[0002]

2. Description of the Related Art Among conventional autorefractometers, those using an optical position sensor have an advantage that the refractive power in each radial direction can be measured at the same time. In this type, the projection light beam and the reflected light beam are split by using a special optical member such as a perforated mirror provided at the pupil conjugate position. On the other hand, a method of splitting using a wavefront splitting member such as a half mirror is also disclosed in, for example, US Pat. No. 4,162,828.

[0003]

[Problems to be Solved by the Invention]

(1) The conventional system that separates the projected light flux and the reflected light flux with a perforated mirror or the like has a problem in downsizing of the optical system because the optical image becomes complicated. Further, since it is necessary to separate them on the pupil, it may not be possible to measure a cloudy eye or the like.
On the other hand, the method of separating by using the wavefront dividing member has a problem in the measurement range, accuracy, etc. because there is no light flux limiting means at the pupil conjugate position.

(2) Further, the conventional autorefractometer uses a very small part of the pupil for measurement, but since the refractive power generally has a non-uniform distribution in the pupil, the entire area is used. There is an inconvenience that the measured value is different from the subjective refraction measurement. On the other hand, subjective refraction measurement takes time, and there are problems that the response may not be reliable depending on the subject.

An object of the present invention is to solve the problem (1),
The projection light flux and the fundus reflected light flux can be separated without using a special optical member, which enables simplification and miniaturization of the structure, and also enables easy correspondence to small pupils and cloudy eyes. The present invention is to provide an eye refractometer.

Another object of the present invention is to provide an eye refractometer which solves the problem (2) and makes it possible to match the objective measurement value with the subjective measurement value and to perform an accurate refraction test in a short time. To provide.

[0007]

A first eye refractometer according to the present invention for achieving the above object comprises a wavefront dividing member for dividing a projected light beam and a fundus reflected light beam, a pupil of an eye to be examined, and a conjugate surface. , A projection optical system for projecting a light flux onto the fundus through the wavefront splitting member and the light flux limiting means, and an optical position sensor for reflecting the fundus reflected light through the wavefront splitting member and another light flux limiting means. And a light receiving optical system for receiving light, and the eye refraction value is obtained from the light beam position on the optical position sensor.

The second ocular refractometer includes an objective lens arranged so that the anterior segment of the eye to be examined is located at the front focal position, a convex lens, a diaphragm arranged at the rear focal position, and refraction in the direction perpendicular to the optical axis. And a wavefront splitting member that is disposed between the focus section and the subject's eye and splits the projection light beam and the fundus reflected light beam, and receives the fundus reflected light beam. And an optical refraction value is obtained from the position of the received light beam on the photoelectric array sensor and the position of the focusing portion.

The third eye refractometer includes an objective lens, an aperture arranged at a conjugate position with the anterior segment of the eye to be examined of the objective lens,
The projection light flux is disposed between the prism conjugate at the pupil conjugate position of the projection system and having a refracting action in the direction perpendicular to the optical axis, the focus lens movable in the optical axis direction, and the pupil conjugate position of the eye to be examined and the objective lens. And a wavefront splitting member for splitting the fundus reflected light flux, and a photoelectric array sensor for receiving the fundus reflected light flux that has passed through the focus lens, and from the received light flux position on the photoelectric array sensor and the position of the focus lens. It is characterized in that the eye refraction value is obtained.

[0010]

In the first eye refractometer having the above-mentioned structure, the reflected light from the fundus of the eye to be examined is split by the wavefront splitting member, and then received by the optical position sensor through the light flux limiting means at the pupil conjugate position. Since the position of the received light flux changes depending on the refractive power of the eye to be inspected, the eye refraction value is obtained by analyzing the position and shape of the received light flux.

The second ocular refractometer is provided with a focus section consisting of a convex lens, an aperture stop and a prism in the optical path, and the focus section is moved to bring about a focus, which is obtained by the position of the focus section and the photoelectric array sensor. The eye refraction value is obtained from the position of the fundus reflected light flux.

Further, the third eye refractometer is provided with a diaphragm, a prism, and a focus lens in the optical path, and the focus lens is moved to bring the focus into focus. The position of the focus lens and the fundus reflected light flux obtained by the photoelectric array sensor The eye refraction value is obtained from the position.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. FIG. 1 shows a first embodiment, and a lens 2, a diaphragm 3 having a central aperture conjugate with a pupil Ep of the eye E, a movable mirror 4, and a half are provided on an optical path O1 from the point light source 1 to the eye E. The projection optical system is configured by arranging the mirror 5 and the objective lens 6, and the reflection point P of the movable mirror 4 is located at the rear focus position of the objective lens 6. Further, on the optical path O2 behind the half mirror 5, there is an optical position sensor 10 including a diaphragm 7 having a ring-shaped aperture conjugate with the pupil Ep, an inverted conical prism 8, a lens 9, and a CCD image pickup element conjugate with the stereoscopic fundus.
Are arranged to form a light receiving optical system. A wavefront splitting member such as a polarizing prism may be used instead of the half mirror 5.

The projected light flux from the point light source 1 reaches the eye E through the lens 2, the diaphragm 3, the movable mirror 4, the half mirror 5 and the objective lens 6, and the fundus reflected light flux reflected by the fundus Er is the objective lens 6. Then, the light is received on the optical position sensor 10 through the half mirror 5, the diaphragm 7 conjugate with the pupil Ep, the inverted conical prism 8 and the lens 9.

Here, since the diaphragm 7 has a ring-shaped opening, a ring light flux R as shown in FIG. 2 is received on the optical position sensor 10. The ring light flux R changes in size depending on the eye refraction value and becomes an ellipse when there is astigmatism. Therefore, the eye refraction value can be obtained by inputting the signal to the computer and analyzing the shape. For the calculation, for example, the elliptical shape may be analyzed by obtaining the intersections of the lines A, B, C, D passing through the center point O shown in FIG.

3 (a) and 3 (b) exemplify the projected light beam L1 and the reflected light beam L2 on the pupil Ep plane, and FIG. 3 (b) shows the case where the turbidity G exists at the center of the pupil Ep. Since it is impossible to project from the center, it is necessary to tilt the movable mirror 4 to remove the position of the projected light flux L1 from the turbidity G. Since the position of the movable mirror 4 is conjugate to the optical position sensor 10, the light beam position on the optical position sensor 10 remains unchanged even if the movable mirror 4 is tilted.

The diaphragm 7 may be a diaphragm having, for example, six openings on the circumference. In this case, if the inverted conical prism 8 is composed of six wedge prisms, six spot light beams are received on the optical position sensor 10. Therefore, these light beam positions are calculated to obtain the eye refraction value. You can

FIG. 4 shows a second embodiment, and the same symbols as in FIG. 1 represent the same or equivalent members. In this case,
The conical prism 11 and the diaphragm plate 12 are arranged on the optical path O1 at the pupil conjugate position of the projection optical system, and the central aperture diaphragm 13 is arranged on the optical path O2 at the pupil conjugate position of the light receiving optical system.
As shown in FIG. 5, the ring diaphragm plate 12 of the projection optical system has two large and small ring diaphragms 12a and 12b. A shaft 15 of the diaphragm plate 12 is rotated by a solenoid 15 to rotate the ring diaphragm 12a. , 12b are switched according to the pupil diameter and used.

In the second embodiment, the case where the area sensor is used as the optical position sensor 10 has been shown, but a line sensor may be used as long as the measurement can be performed only in the meridian direction. Further, the half mirror 5 is used as the light splitting member for splitting the projection light flux L1 and the fundus reflected light flux L2 in the embodiment, but a member splitting by polarized light may be used, and this light splitting member is provided in front of the objective lens 6. May be provided. In any case, no special optical member is required for splitting the projection light beam L1 and the fundus reflected light beam L2, and therefore the configuration is significantly simplified. Moreover, since it is not necessary to separate the projected light flux L1 and the fundus reflected light flux L2 on the pupil plane, it is possible to easily deal with small pupils and opaque eyes.

FIG. 6 shows a third embodiment, in which the lens 2 is provided on the optical path O3 from the point light source 21 such as an LED to the eye E to be examined.
2, and the diaphragm 24 having the optical axis light shielding member 23 and the lens 2
A projection-side focus unit 26, which is integrated with 5, and a mirror 27, an objective lens 28, and a half mirror 29 are arranged. On the optical path O4 behind the half mirror 29, the objective lens 30, the light receiving side focus unit 34 in which the lens 31, the diaphragm 32 and the separation prism 33 are integrated and interlocks with the projection side focus unit 26, the lens 35, CC.
A photoelectric array sensor 36 made of D or the like is arranged.

Lens 22, lens 35 and objective lens 28
And the objective lens 30 are the same, and the point light source 21
And the photoelectric array sensor 36 are conjugate with respect to the half mirror 29. Further, the diaphragm 23 and the diaphragm 32 shown in FIGS. 7A and 7B are located at the rear focal positions of the lens 26 and the lens 31, respectively, and the pupil Ep is located at the front focal position of the objective lens 28 and the objective lens 30. .

The light beam from the point light source 21 is collimated by the lens 22 and then passes through the projection side focus unit 26.
The light flux that has passed through the projection-side focus unit 26 is reflected by the mirror 27, then passes through the objective lens 28, and is reflected by the half mirror 29 to project a spot light flux onto the fundus Er of the eye E to be inspected. Part of the light flux reflected from the fundus of the eye is the half mirror 2.
9. The lens 31, the diaphragm 32, and the separation prism 33 of the light-receiving side focus unit 34, passing through the objective lens 30.
6 through the lens 35 on the photoelectric array sensor 36.
Each spot light beam is received.

7 (a) and 7 (b) show the shapes of the diaphragm 23 and the diaphragm 32, respectively, and show the focus unit 26 on the projection side.
The optical axis shading portion 24 of the diaphragm 23 plays a role of removing corneal reflected light. The optical axis light shielding unit 24 is a diaphragm 3 on the light receiving side.
However, there is a risk that the measurement light beam may be eclipsed.
As shown in FIG. 8, the separation prism 33 is composed of six wedge prisms symmetrical about the optical axis, and has a function of separating a light beam for each meridian.

Therefore, the photoelectric array sensor 36 is shown in FIG.
As shown in FIG. 6, six spot light beams S1 to S6 are received.
The projection-side focus unit 26 and the light-reception-side focus unit 34 are integrally moved in the respective optical axis directions as indicated by an arrow F, and the point light source 21 and the photoelectric array sensor 36 are focused so as to be conjugated with the fundus Er. It Then, the eye refraction value is calculated by the computer from the position and the spot light beam position.

Spot light flux S1 on the photoelectric array sensor 36
The distance between S4 and S4 changes linearly with respect to the diopter of the refractive index of the eye E when the eye E is in focus. In the measurement, for example, while focusing on the signal on the line H, the focus is focused, and when the spot light flux is best matched, the light is stopped, and the six spot light fluxes are
By calculating the positions of S1 to S6, the eye refraction value including astigmatism can be obtained.

If there is astigmatism, the other spots are slightly blurred but their center of gravity is calculated. The other two pairs of spot intervals with respect to the focused horizontal spot pair similarly change in a linear relationship with the diopter change.

In this embodiment, unlike the conventional case, it is not determined only from the position of the focus lens.
Since both the spot position and the lens position are used, the focus can be calculated accurately without making the focus so strict.

A conical prism may be used in place of the separating prism 33 shown in FIG. 6, but in this case, the light beam has a ring shape, and therefore its shape may be analyzed. Further, the separating prism 33 may be provided near the diaphragm 23 on the projection side, and in this case, six spots are projected on the fundus.

The aperture 23 has a very small diameter, for example 1 mm.
In the following cases, since there is almost no blur, the projection optical system does not necessarily need to be focused. In that case, it suffices to focus only on the light receiving side. Further, the half mirror 29 of FIG. 6 may be replaced with a prism, but in that case, it is necessary to tilt the surface to fly the reflected light. If the position is placed behind the objective lens 28 and the objective lens 30, it is possible to use only one objective lens, but it is necessary to take measures against surface reflection due to this.

FIG. 10 shows a fourth embodiment, which is a point light source 41.
The focus lens 4 is provided on the optical path O5 from the eye E to the subject E.
2, a diaphragm 43, a lens 44, a mirror 45, a half mirror 46, and an objective lens 47 are arranged, and a lens 48, a diaphragm 49, a separation prism 50, and a focus lens 42 are integrated in an optical path O6 behind the half mirror 46. A focus lens 51 and a photoelectric sensor array 52 are arranged.
The diaphragm 43 on the projection side and the diaphragm 49 on the light receiving side are the pupils.
It is located at the conjugate position with Ep.

In this case, the light flux from the point light source 41 has a focus lens 42, a diaphragm 43, a lens 44, and a mirror 4.
5, through the half mirror 46 and the objective lens 47, is projected onto the fundus Er of the eye E to be examined, and the reflected light flux from the fundus of the eye passes through the objective lens 47, the half mirror 46, the lens 48, the diaphragm 49, the separation prism 50, and the focus lens 51, and is photoelectrically converted. The light is received by the array sensor 52.

Here, the lenses 44 and 48 collimate the light flux into parallel light. This acts to balance the change of the spot light flux on the photoelectric array sensor 52 with respect to the plus side diopter and the minus side diopter. The focus lenses 42 and 51 are integrally moved in each optical axis direction, and the point light source 41 and the photoelectric array sensor 52 are focused so as to be conjugated with the fundus Er. The eye refraction value is obtained from the six spot positions on the photoelectric array sensor 52 and the focus lens position at that time, as in the case of the embodiment shown in FIG. As described above, the change in the spot distance at the in-focus position changes in the same amount in the positive and negative sides in the same direction, but the change is not linear with respect to diopter.

However, for a certain focus lens position, the spot spacing changes linearly with diopter changes. Therefore, as in the case of the embodiment of FIG. 6, for example, at a position where the horizontal spot pair is substantially focused,
The eye refraction value can be obtained by calculating the distance between the other two pairs of spot positions.

The separation prism 50 is a diaphragm 4 on the projection side.
You may arrange | position in the vicinity of 3. Further, if the light flux on one side is made thin, it is not necessary to focus. In the case of the embodiments shown in FIGS. 6 and 10, since the objective measurement can be performed using the entire pupil area, accurate measurement values can be obtained.

[0035]

As described above, the first ocular refractometer according to the present invention does not require a special optical member for splitting the projection light beam and the fundus reflection light beam, so that the structure is simplified and the cost is reduced. It is also advantageous for downsizing. Further, since it is not necessary to separate the projected light flux and the fundus reflected light flux on the pupil plane, it is possible to deal with small pupils and opaque eyes.

Further, the second and third eye refractometers can objectively measure the entire pupil area and can obtain accurate measured values in a short time.

[Brief description of drawings]

FIG. 1 is an optical layout diagram of a first embodiment.

FIG. 2 is an explanatory diagram of a fundus reflected light flux on an optical position sensor.

FIG. 3 is an explanatory diagram of a projected light flux on a pupil plane and a fundus reflected light flux.

FIG. 4 is an optical layout diagram of a second embodiment.

FIG. 5 is an explanatory diagram of a diaphragm.

FIG. 6 is an optical layout diagram of a third embodiment.

FIG. 7 is an explanatory diagram of a pupil conjugate diaphragm.

FIG. 8 is an explanatory diagram of a separation prism.

FIG. 9 is an explanatory diagram of a fundus reflected light flux on the photoelectric array sensor.

FIG. 10 is an optical layout diagram of a fourth embodiment.

[Explanation of symbols]

 1, 21, 41 Point light source 5, 29, 46 Half mirror 10 Optical position sensor 11 Conical prism 12 Aperture plate 26 Projection side focus unit 31 Light receiving side focus unit 36, 52 Photoelectric array sensor 42, 51 Focus lens

Claims (3)

[Claims] 1. A wavefront splitting member for splitting a projected light flux and a fundus reflected light flux, a light flux limiting means arranged on a conjugate plane with a pupil of an eye to be examined, and a light flux projected on a fundus through the wavefront splitting member and the light flux limiting means. Projection optical system, and a light receiving optical system for receiving the fundus reflected light to the optical position sensor via the wavefront splitting member and another light beam limiting means, and the eye refraction value from the light beam position on the optical position sensor. An eye refractometer that is characterized by seeking. 2. An optical system comprising an objective lens arranged so that the anterior segment of the eye to be examined is at the front focal position, a convex lens, a diaphragm disposed at the rear focal position, and a prism refracting in the direction perpendicular to the optical axis. A focus unit that can move in the axial direction,
A wavefront splitting member, which is disposed between the focus section and the eye to be examined, splits a projection light beam and a fundus reflected light beam, and a photoelectric array sensor for receiving the fundus reflected light beam, and a light receiving unit on the photoelectric array sensor An eye refractometer, wherein an eye refraction value is obtained from a light beam position and a position of the focusing portion. 3. An objective lens, a diaphragm arranged in a conjugate position with an anterior segment of an eye to be inspected of the objective lens, and a prism located at a pupil conjugate position of a projection system and having a refracting action in a direction perpendicular to an optical axis,
A focus lens that is movable in the optical axis direction, a wavefront splitting member that is provided between the eye to be inspected and a pupil conjugate position of the objective lens, and splits a projection light beam and a fundus reflected light beam, and a fundus that has passed through the focus lens. An eye refractometer, comprising: a photoelectric array sensor for receiving a reflected light beam; and obtaining an eye refraction value from the position of the received light beam on the photoelectric array sensor and the position of the focus lens.