JPH0323835A - Apparatus for measuring eye refractive force - Google Patents

Abstract

PURPOSE:To make it possible to obtain in a moment a result of a measurement and to measure the degree of astigmatism, the axis angle of astigmatism, etc., by providing a mask plate selectively transmitting light fluxes from a plurality of longitudinal lines and providing a light protection member protecting a part of a reflected light flux of the each selected light flux in the light path of a light receiving system. CONSTITUTION:A light projection system 1 consists of a light source 4, a half mirror 5 reflecting a light flux from the light source to an examined eye 3 and a flare protecting device 28 set on the opposite side of the light source therefrom. The light source consists of an illuminant 15, an IR rays filter 16, a mask plate 17, a condenser 18, a diffuser panel 19 and a slit panel 20. A light receiving system 2 consists of an objective lens 8 and a light receiving element 9 and in a light path, an edge-like light protection member 12 protecting a half side of the light flux defining an optical axis of the objective lens as a boundary is positioned vertically to the optical axis at a position where an image of the light source is formed when the eye refractive force of the examined eye is at a level of a standard value 1. A condition where the light flux is protected by means of the light protection member is changed thereby depending on the difference in the eye refractive force of the examined eye. This condition of light protection corresponds to the eye refractive force and it is possible to measure the eye refractive force based on the light vol. distribution. In addition, the condition of astigmatism is measured by separating with time the light vol. distribution on a plurality of longitudinal lines.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an eye refractive power measuring device, and particularly to an eye refractive power measuring device that is useful for children and infants.

C. Prior Art] Conventionally, as an eye refractive power measuring device, there is a so-called subjective ophthalmoscope that measures the eye refractive power based on the response of the examinee, and a so-called autorefraction meter that measures the eye to be examined objectively. Such devices are known.

However, when measuring infants with this type of device,
Measurements cannot be performed with a subjective ophthalmoscope because the infant's cooperation cannot be obtained, and with a general autorefractometer, the position of the eye to be examined must be fixed, and in the case of infants, it is difficult to fix the position of the eye to be examined. It had the disadvantage that measurement was extremely difficult.

In order to eliminate these shortcomings, a so-called photographic method is used in which the fundus of the eye to be examined is illuminated with a robot light, the state of the light flux at the pupil of the eye to be examined is photographed with a camera, and the ocular refractive power of the eye to be examined is measured from the results. 1. A refraction measurement method has been proposed.

In this photo 1 - refraction method measurement, sufficient measurements can be made even if the optical axis of the eye to be examined is slightly shifted, and it is difficult to fix the eye to be examined when measuring the refractive power of an infant's eye. It is said to be useful for.

[Problems to be Solved by the Invention] However, in such a photorefraction type eye refractive power measurement device, a mask plate is provided that illuminates the optical axis of the camera with a strobe light source from an oblique direction and selectively transmits the strobe light. , characterized in that a light shielding member is provided in the optical path of the light receiving system to shield a part of the reflected light flux of each of the selected light fluxes, and further includes a measurement light source, and the measurement light source is provided at the fundus of the eye to be examined. It has a projection system for projecting an image, and a light receiving system for guiding the reflected light flux from the fundus onto a light receiving element placed at a position approximately conjugate with the pupil of the eye to be examined. In an eye refractive power measuring device that measures the eye refractive power of the eye to be examined from the light intensity distribution of the pupil image, the light source emits measuring light in different wavelength bands from positions on multiple meridians, and the light receiving system The present invention is characterized in that a light shielding member is provided in the optical path to shield a part of the reflected light beam in each wavelength band, and a dichroic mirror is provided to separate the reflected light beam that has passed through the light shielding member into each wavelength band.

[Operation] Depending on the difference in the eye refractive power of the eye to be examined, the state in which the light beam is blocked by the light blocking member differs. This state of light shielding corresponds to the eye's refractive power, and the problem is that the pupil image is simply taken at 5 o'clock when it is projected onto the light receiving element, and there are some diopter values that cannot be measured depending on the position of the light source, and the measurable range is narrow. have.

Furthermore, conventional devices of this type have not taken into account measurements of astigmatism, such as the degree of astigmatism and the angle of the astigmatism axis.

The present invention was made in view of the above-mentioned circumstances, and it is an object of the present invention to provide an eye refractive power measuring device that can obtain measurement results instantaneously and also measure the degree of astigmatism, astigmatic axis angle, etc.

1. Means for Solving the Problems] The present invention includes a projection system that includes a measurement light source and projects a measurement light source image onto the fundus of the eye to be examined, and a projection system that has a measurement light source and a projection system that projects the image of the measurement light source onto the fundus of the eye to be examined, and a fundus that is placed on a light-receiving element disposed at a substantially conjugate position with the pupil of the eye to be examined. In the eye refractive power measuring device which has a light receiving system for guiding the reflected light flux from the light receiving element and measures the eye refractive power of the eye to be examined from the light intensity distribution of the pupil image of the eye to be examined formed on the light receiving element, The eye refractive power can be measured based on the state of the light beam that is projected by the light source from a plurality of meridians, that is, the light intensity distribution. or,
Astigmatism can be identified by measuring the eye refractive power along multiple meridians, and in the first invention, the light intensity distribution for multiple meridians is measured separately in time, and in the second invention, the measurement light flux is divided into different wavelengths. Separate and measure each.

[Actual travel example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Astigmatism is caused by the difference in eye refractive power (diopter value) at each meridian, and the state of astigmatism is sphericity S, astigmatism C
, can be specified by measuring the astigmatic axis angle A. Further, the relationship between the deopter value D at a meridian of an arbitrary angle θ, the degree of sphericity S, the degree of astigmatism C, and the astigmatic axis angle A is expressed by the following formula.D. 9 = S0C Sin (θ-A) - (1)
Therefore, by calculating the teopter values of the three meridians θ1, θx, and θ3, the spherical power S, astigmatic power S, and astigmatic axis angle A can be determined, and the astigmatism state can be identified.6 Below, in Figures 1 to 4, A first embodiment of the present invention will now be described.

1 is a projection system for projecting a light source image onto the fundus 7 of the eye 3 to be examined; 2 is a light receiving system for receiving the light beam 10 reflected by the fundus 7; the projection system 1 and the light receiving system 2 are It is arranged opposite to the optometry clinic 3.

The projection system 1 includes a light source 4 and a half mirror 5 for reflecting the light beam 11 from the light source 4 toward the subject's eye 3 in the G direction, and a flare preventer 28 disposed opposite the light source of the half mirror 5.
The projection system 1 directs a light beam 11 from a light source 4 to a pupil 6.
An image of the light source 4 is projected onto the fundus 7 through the lens.

The light source 4 also includes a light emitting body 15 having tanksten filaments 1 to 1, an infrared filter 16, a mask plate 17,
It is composed of a condensing lens 18 such as a Fresnel lens, a diffuser plate 19, and a slit plate 20.

The mask plate 17 is rotatably supported and has a white and wide light projection window 21 formed on the outer peripheral side on a required meridian. Further, the light passes through the mask plate 5 and is guided onto the light receiving element 9.

The light-receiving element 9 is an area COD, an image pickup tube, or an assembly of two or more light-receiving elements, and the light-receiving surface 9a of the light-receiving element 9 is arranged at a conjugate position with the pupil 6 of the eye 3 to be examined with respect to the objective lens 8.

In the optical path of the light-receiving system 2, a single measurement of the light beam 10 is arranged with the optical axis O of the objective lens 8 as a boundary at a position where a light source image is formed when the eye refractive power of the eye 3 to be examined or the reference diopter value is used. An etched light shielding member 12 for shielding light is arranged in a plane perpendicular to the optical axis.

The light shielding member 12 has each of the slit holes 20a and 20b2.
Etched ridge lines 25a, 2 perpendicular to the meridian of 0c...
A hexagonal transparent hole 25 having a diameter of 5b, 25c, . . . is bored.

Further, the video camera 26 into which the light receiving element 9 is introduced extracts a signal from the light receiving element 9 by the control section 27 and inputs it to the computing unit 13 as a video signal for video together with a video synchronizing signal.

A calculator 13 calculates the light receiving state of the light receiving element 9 based on the video signal, and based on the light receiving state, the eye refractor 917 is rotated at a predetermined speed by a motor 22 as described later. .

The slit plate 20 has holes 20a to the slit 1, which become wider toward the outer circumference, at positions on six meridian lines that equally divide the center.
The flare preventer 28 will be explained.

A plurality of strip-shaped absorption plates 23 are arranged in parallel with their surfaces inclined with respect to the optical axis of the projection system 1, and an absorption wall 24 is provided opposite to the half mirror 5 of the absorption plates 23.

The absorption wall 24 may be the inner surface of a lens barrel that houses the optical system.

Both surfaces of the absorption plate 23 and the absorption wall 24 are coated with antireflection coat I or black antireflection paint.

Such a flare preventer 28 attenuates the light from the light source 4 that has passed through the half mirror 5 by reflecting it multiple times on the absorption plate 23 and the absorption wall 24, and the light that has passed through the half mirror 5 is received by the light receiving system 3. Preventing damage.

The light-receiving system 2 is composed of an objective lens 8 and a light-receiving element 9, and is configured to calculate the half-mirror force and astigmatism state of the light beam 10 from the fundus 7 and output it to the display 14.

Further, the computing unit 13 controls the speed of the motor 22 via a drive unit 29 in order to synchronize the rotational speed of the mask plate 17 of the light source 4 with the video signal.

30 indicates an encoder for detecting the rotation of the motor.

A Hall element 31 is provided for the mask plate 17 (4-)
Also, a minute magnet 32 for speed detection and a minute magnet 33 for position detection corresponding to the slit position are drilled in the mask plate 17, and the Hall element 31 detects the minute magnets 32 and 33 and The signal is sent to the arithmetic unit 13
It is now possible to input the .

The action will be explained below.

As mentioned above, astigmatism can be measured by measuring the diopter values of three meridians, so first, the measurement of diopter values for one meridian will be explained with reference to FIGS. 5 to 1-3.

The following explanation assumes that a hole, for example 20a, matches the light projection window 21 and one of the slits 1, and the bundle of light 10 is blocked by the edge-like ridgeline 25a of the light blocking member 12. .

As shown in FIG. 5(^), when the diopter value of the eye 3 to be examined is negative compared to the reference diopter value, the image of the light source 4 is formed in front of the fundus 7, and this light beam forms an image in front of the fundus 7. Considering a light beam 10 reflected at one point on the optical axis on the illuminated fundus 7, this light beam 10 is reflected by the light shielding member 12.
The upper half (shaded area) of the light beam that is focused in front of the subject's eye 3, and projected onto the light receiving element 9 by the objective lens 8.
is shaded. On the other hand, as shown in FIG. 5(B), when the diopter value of the eye to be examined is the reference diopter value, the light beam 10 is focused on the light shielding member 12'', and the light beam 1
0 is not blocked by the light blocking member 12.

Further, as shown in FIG. 5(C), when the diopter value of the eye 3 to be examined is more positive than the reference diopter value, the image of the light source 4 is projected so as to form behind the fundus 7, and as described above. Similarly, the light beam 10 reflected by the fundus 7 is behind the light shielding member 12,
That is, with reference to the light-receiving element 9 and FIGS. 6(8) to 6([), the distribution of the amount of light formed on the light-receiving surface 9a will be explained.

In addition, in order to simplify the explanation in FIGS. 6(c) to (1)), the optical axis of the light source 4 and the optical axis of the light receiving system are aligned, and the light shielding member 12 and the objective lens 8 are aligned. I'm letting you do it. Therefore, the light source 4 and the objective lens 8 are shown superimposed at the same position, and the light shielding member 12 is omitted.

In FIG. 6 (8) to ([), the refractive power D of the eye to be examined is the reference refractive power D. In the following explanation, all the reflected light flux from the fundus is reflected by the objective lens 8 on the light receiving surface 9aJ.
: shall be projected to.

The distance between the light source 4 and the pupil 6 of the eye to be examined is set to 2, and the refractive power of the eye to be examined where the image of this light source is focused on the fundus is the reference refractive power D. Then, it is.

FIG. 6(A) shows a point S on the axis of a slit-shaped light source 4 having a length I in the direction perpendicular to the optical axis when the refractive power of the eye to be examined is D (<D.). The luminous flux 1 is focused from 13 to 1 and projected onto the light receiving element 9 -lx.
0, a part of the light beam opposite to that shown in FIG. 5 (8) (the upper half in the figure) is blocked.

The light flux projected onto the light-receiving surface 9a changes in its light quantity distribution state depending on the magnitude and sign/minus of the diopter value of the eye to be examined 3 with respect to the reference diopter value, and the diopter value is determined based on this light quantity distribution state. .

The light-receiving element 9 is for detecting the light intensity distribution of the light flux formed on the light-receiving surface 9a, and the arithmetic unit 13 detects the distribution of the light flux formed on the light-receiving surface 9a based on the signal from the light-receiving element 9. It detects the light intensity distribution, determines whether the eye refractive power of the eye to be examined is positive or negative with respect to the reference diopter value, calculates its absolute value, and outputs the calculation result to the display 14.
4 displays the obtained results.

Incidentally, in the above embodiment, a half mirror is used as the beam separating means, or it goes without saying that various beam separating means such as a beam splitter 1 polarizing prism may be used.

? Point S indicates the projected light flux. The image is once formed on So', and is projected onto the fundus 7 of the subject's eye as a blurred image. D. As -D becomes larger, the projected area 7a becomes wider.

FIG. 6(B) shows the state of the light flux reflected from the light receiving system 2 and the fundus 7 of the eye to be examined.

As shown in FIG. 6(B), considering the light flux from the point I-■ at the end of the projection area on the fundus 7 of the subject's eye, the image of this point ■-
1' is imaged at a position 2' from the pupil of the eye to be examined, and this light beam is projected via the objective lens 8 onto a light receiving element 9'2 disposed at a position conjugate with the pupil 6 of the eye to be examined. Furthermore, this 9'
The relational expression between D and the refractive power D of the eye to be examined is as follows.

On the other hand, the spread width Δ at the etch of the light beam emitted from a single point in the fundus is shown in Figure 6 (
As is clear from B), Equation (1) and Equation (2)
From the formula, 14 is obtained, and the refractive power D of the eye 3 to be examined and the reference refractive power D.

The larger the difference, the larger the spread on the light shielding member 12.

Next, the spread of the light beam at the light receiving element 9'2 will be described. The light receiving element 9 is always arranged in a conjugate manner with the pupil of the eye to be examined with respect to the objective lens 8, regardless of the refractive power of the eye to be examined 3. If the diameter of the pupil of the eye to be examined 6 is U, and the magnification of the objective lens 8 is β, then On the light receiving element 9, a light beam is projected onto an area having a diameter of βU (which is not affected by the refractive power of the eye to be examined).

Also, the above I- with respect to the optical axis. Similarly, the light beam from point I, which is symmetrical to , forms an image ■ at the position Q' from the pupil 6 of the eye to be examined. ' Tie 1
After imaging, it is projected onto the same area βU on the light receiving element 9.

If the light source 4 is a point light source, all of the light beam will be blocked. Therefore, the etched light shielding member 12
Therefore, the light on the light receiving element 9 becomes darker as it goes upward, and the light amount becomes 0 at the point Pn, resulting in a light amount distribution with a constant slope.

In the above FIGS. 6(^) to (C), only the light beam emitted from one point on the optical axis of the light source 4 is shown, or one point S- at the end of the light source 4 is shown. (It becomes as shown in FIG. 6 (D) where the size of the light source is L. The light flux from this point S-1 is transmitted from point I-1 of the fundus 7 1 of the subject's eye shown in FIG. 6 (D). I. Projected onto the area of points, this ■ one.

The reflected light from one point is the pupil 6 of the eye to be examined, as described above.
At a distance of Q' from I. ,I.

After forming an image, it is projected onto a region having a diameter of βU on the light receiving element 9. Here, the point S- at the end of the light source 4,
Of the light beams emitted from the light receiving element 9, the light beams incident on the end position P-1 of the light beam projection on the light receiving element 9 are the light beams in the shaded area B in FIG. 6(D).

17 Each point ■- from the fundus 7 when the light shielding member 12 is not provided. , . . . Io, .

Here, in order to consider the light quantity distribution on the light receiving element 9, the end position P- of the light beam projection position on the light receiving element 9. , that is, a locus centered on the optical axis? The luminous flux incident on the position is limited to the luminous flux within the range indicated by the diagonal line A in FIG. 6(C). Similarly, the above-mentioned P- with respect to the optical axis. Considering the luminous flux incident on the position Hp2 which is symmetrical to the position, the luminous flux is limited to the range of the diagonal line A'. As a result, if an etched light shielding member 12 is placed at a distance Q from the pupil 6 of the eye to be examined (a position conjugate with the light source 4), P- on the light receiving element 9 is placed. . The light flux incident on the position P- is not blocked by the light shielding member 12. The light beam is gradually blocked as it moves upward from the position of P.
.

At the position P9, half of the luminous flux is blocked, and at the position P9, the S-. Considering the light flux from one point So of the light source 4 which is symmetrical to the point , and considering the light flux incident on the point P-7 on the light receiving element 9, it becomes the light flux in the shaded area C in FIG. 6([). In this way, when considering the light source 4 as having a certain size, the amount of light at one point on the light receiving element 9 must be considered as the sum of the luminous fluxes from each point of the light source 4.

FIG. 7 (^) shows P- on the light receiving element 9 based on this idea. The light beams incident on the position S-1 are shown superimposed, and P- is the light beam emitted from the position S-1 on the light source. The light flux incident on the position So is in the area B (see Fig. 6 (D)), and as the position on the light source goes upward, the light flux also moves upward, and at the light source position So on the axis,
(see Figure 6(C)), and S on the light source. At the position , the light beam is in the area C (see FIG. 6 ([)). Therefore, the amount of light at point P-1 on the light receiving element 9 is:
It can be considered as the sum of these luminous fluxes.

Here, a schematic diagram showing the amount of light at a point P-1 on the light receiving element 9 when the light shielding member 12 is placed at a distance Q from the pupil 6 of the eye to be examined is shown in FIG. 7 (8).

FIG. 7(8) shows how the light beam is blocked by the light blocking member 12 as the position on the light source changes. The horizontal axis of Fig. 7 (B) is the coordinate position of the light source,
The vertical axis indicates the amount of light, and considering the light flux from each point on the light source, the light flux at the coordinate position is not blocked by the light shielding member 12, and when it passes the 0 point of the coordinate position, it is gradually blocked,
All of the light flux is blocked at the position Δ (the above-mentioned spread of the light flux). Figure 7 (B) shows the contribution of the amount of light from each point on the light source, where k is the amount of light from each point on the light source when the light is not blocked. P-. This corresponds to the light amount value at the point. This area value T is as follows.

Similarly, other points on the light receiving element will also be considered. Is Fig. 8 (8) the center on the light receiving element? A from the point o
The light flux from the point P-■ on the light source in the shaded area "C" is shown as the light flux in the shaded area C''. In this case, Fig. 9 (B
), the light beam is not blocked from each point of the light source to the point Pゎ of the light receiving element, and after passing the 1∆ position, the light beam is gradually blocked, and at the 0 position, all the light beams are blocked. The light beam will be blocked, and the area value will be calculated as follows.

As can be seen from the results of these equations (6), (7), and (8), the light M value on the light receiving element 9 gradually decreases from the bottom to the top. When the light intensity distribution on the light receiving element is illustrated, it changes linearly as shown in FIG.

In the above description, the spread on the light shielding member 12 was explained based on the light beam emitted from one point on the fundus of the eye.

21 points P. The light flux incident on the light source is shown in the same way as in FIG. The luminous flux incident on the point is B. Shaded area, center S of light source-L
. A from the point of view. In the shaded area, the luminous flux from 87 points on the light source is C. The amount of light incident on the center of the light receiving element 9 corresponds to the area To of the shaded area in FIG. 8(B). In other words, the light beams incident on the center point of the light receiving element from each point of the light source are blocked, and when the area value is calculated in the same manner as described above, it becomes the following value.

Similarly, point p on the light receiving element. Figure 9 (8) and Figure 9 (8) show the state of the luminous flux incident on the point and the light amount value at this point.
). In FIG. 9(A), among the light fluxes from point S-1 on the light source, the light flux incident on point P5 is in the shaded area B', the center value D on the light source. If the deviation ΔD of the diopter value of the eye to be examined with respect to is more than a predetermined amount, a linear change as shown in FIG. 13 is not shown. This will be explained as shown in FIGS. 7 and 8. As mentioned above (B), No. 9
14, FIG. 15, and FIG. 16, respectively, and this light amount change does not show a linear change as shown in FIG. 10.

Next, if the refractive power of the eye to be examined is the standard value as shown in FIG. 5(B), and if the refractive power of the eye to be examined is more positive than the standard value as shown in FIG. 5(C), the same applies as above. In this case, if the refractive power of the eye to be examined is the reference value, it will be a uniform distribution, as shown in Figure 11, and if the refractive power of the eye to be examined is positive, it will be The distribution state is opposite to that shown in FIG.

The slope of the above-mentioned light quantity distribution or diopter value (refractive power) is expressed, and the direction of the slope: ] or the positive or negative value of the diopter value is expressed. This will be explained below with reference to FIG.

The spread Δ of the luminous flux described above, that is, the amount of blur ΔG,
) From equation (7), ΔfuΔD Therefore, equation (11) is the reference diopter value D. It is possible to determine the difference ΔD in diopter value of the eye to be examined from the difference ΔD in diopter value of the eye to be examined. Therefore, the diopter value D of the eye to be examined can be calculated using the following formula.

D=D. 1 ΔD = - (12), and each scan is performed using the same J9J (No. g (hereinafter referred to as video signal)
is started by. Therefore, in order to obtain a signal for one screen (one frame), two video signals are generated, and these video signals are equidistant in time.

The speed control of the motor described below is performed using this video signal as a reference so that the number of speed detection signals transmitted from the pole element 31 becomes a predetermined value.

In Figures 17 (FA), (B), and (C), the two stages show the video signal, and the lower stage shows the speed detection pulse signal.

When the motor 22 starts rotating, the rotation speed is low and the speed detection pulse is smaller than a predetermined value for a video signal corresponding to one frame (in the figure, eight frames per pulse). Therefore, the computing unit 13 issues a command to the drive unit 29 to increase the speed. The drive unit 29 increases the speed of the motor 22 based on the command, and monitors based on the signal from the encoder 30 whether the speed of the motor 22 matches the command.

25 Is it possible to obtain the deopter value for one meridian as described above? The deopter value for the other two meridians can be determined by rotating the mask plate and adjusting the position of the mask plate to, for example, 60 degrees.
° Next, when 1206 is reached, the light flux from the light source 4 may be obtained by being sequentially blocked by the etched ridge lines 25b, 25c, . . . of the light blocking member 12.

That is, by selecting the three slit holes of the slit plate 20 and the three etched ridge lines of the light shielding member 12 and measuring the diopter value at each position, the spherical power S and the astigmatic power C can be determined by the above equation (1). , the astigmatic axis angle A can be immediately determined.

Next, speed control of the motor 22 will be explained using FIGS. 17(A), 17(B), and 17(C).

Here, the motor 22 will be explained as a pulse motor.

Image signal or light receiving state of light receiving element 9, light receiving surface 9aJ:
It is obtained by scanning the optical/electronic signal at each point and making it correspond to the position of each point. Normal scanning is divided into odd numbered and even numbered scanning lines and the speed of the motor 22 is set to a predetermined value. Then, the video signal and the rotational position of the mask plate 20 are synchronized. This is to ensure that a portion of the light beam of the captured image signal is accurately blocked by the light blocking member 12 when the image signal is captured.

Assume that there is a time difference of Δt between the video signal and the speed detection pulse when the speeds are synchronized (Figure 17 (B)
).

The arithmetic unit 13 calculates the time difference Δ1, and performs speed control so that ΔL is eliminated. There are various ways to control the speed. For example, from the time when synchronization is applied, the pulse interval for driving the motor is decreased for a predetermined period of time (increasing the speed), the next video signal, or the next video signal. The Δt is set to zero at the time of the signal.

When the video signal and the speed and rotational position of the mask plate 20 are synchronized, when the detection signal of the position detection magnet 32 is input from the Hall element 31, the image signal for one frame at that time is captured. 26 The above-mentioned light amount distribution is obtained from the image signal, and the eye refractive power and astigmatism state are further measured.

The position detection signal from the Hall element 31 is transmitted to each slit hole 2.
Since it is emitted corresponding to 0a, 20b, 20c, etc., it is possible to measure data at 3 meridians and 6 locations.

Note that the slit holes 20a, 20b, 20c...
The light projection window 21 has a so-called elongated trapezoidal shape (each end face should be curved).This is because the light intensity distribution is measured in the above measurement, so that the light intensity on the center side and the peripheral side is made uniform. There are things.

Next, a second practical example will be explained with reference to FIGS. 18 to 20.

In FIG. 18, the same parts as those shown in FIG. 1 are given the same reference numerals.

In the second embodiment, the light source 4 is formed into an ellipse including a light emitting body 15, a diffusion plate 19, and a slit 1 to a plate 35 which also serve as wavelength selection filters.

The slit plate 35 has slit window portions 35a, 35+), 35 corresponding to the slit holes in a transparent plate such as glass.
The light receiving element 9Z is arranged so as to be able to receive the light reflected by the C mirror 9y, and the light reflected by the tychroic mirror 92, respectively, and these light receiving elements 9x, 9y9Z are arranged so that they can receive the light reflected by the mirror 9y, and the light receiving element 9Z receives the light reflected by the mirror 9y. Needless to say, it is arranged at a position conjugate with the pupil 6 of the eye 3 to be examined.

In this embodiment, the light receiving element 9x has an etched ridge line 25a.
The light receiving element 9y receives the reflected light beam of only 800 to 840 nm that is blocked by the etched ridge line 25b, and the light intensity distribution of the light beam is determined. is the etch-like ridge line 2
Only the wavelengths of 8130 to 920 nm, which are blocked by 5c, are received, and light intensity distributions at different meridian positions are obtained.

The computing unit 13 can determine the eye refractive power in the three meridian directions based on these three kinds of light intensity distributions, and can also measure the astigmatism state.

Note that the selection of the wavelengths described above is just an example, and various selections may be made as long as they do not interfere.Two wavelengths are provided on a meridian dividing the center into three equal parts, and the other portions are made opaque. Next, each slit 1 to window portion 35a, 35b, 35
c is coated, and the slit window portion 35c is 880~
Filter that transmits a wavelength of 920 nm, slit window part 3
5b is 840-880n. A filter that transmits only m wavelengths, and a filter that transmits only wavelengths of 800 to 840 nm.

The shape of the transmission hole 25 formed in the light shielding member 12 is, for example, triangular, corresponding to the arrangement of the windows 35a, 35b, and 35c in the slit 1.

Next, two tychroic mirrors 36y and 36z are disposed on the anti-light-shielding member 12 of the objective lens 8 with their reflecting directions changed. One dichroic mirror 36V is 88
The mirror 362 is configured to reflect only wavelengths from 0 to 920 nm, and the other guichroic mirror 362 is configured to reflect only wavelengths from 840 to 880 nm.

It goes without saying that the light receiving element 9x receives the light transmitted through the tychroic mirrors 9y and 9z, and the light receiving element 92 receives the tichroic light.

[Effects of the Invention] As described above, according to the present invention, it is possible to measure diopter values for a plurality of meridians, it is possible to measure astigmatism, and since the light receiving system uses a light receiving element, the measurement results are instantaneously obtained. It exhibits excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram showing the first embodiment of the present invention;
The figure is a view taken along the line A-A in Figure 1, Figure 3 is a view taken along the line B-B in Figure 1, Figure 4 is a view taken along the line C-C in Figure 1, and Figure 5 (A) (
B) (C) is an explanatory diagram showing the difference in the state of the light flux due to the difference in the diopter value of the eye to be examined in this example, and Figure 6 (^) (B) TC) (D) (E) is the light receiving system. and an explanatory diagram showing the state of the reflected light flux from the fundus of the eye to be examined, FIG. 7 (8)
, FIG. 8(A), FIG. 9(A) is an explanatory diagram showing the state of the reflected light flux at each point of the light source reaching the light receiving element, FIG. 7(B),
Fig. 8 CB) and Fig. 9 (B) are explanatory diagrams showing changes in the light intensity of each luminous flux when blocked by a light shielding member, Fig. 30 Fig. 10, Fig. 11, and Fig. 12 are light reception corresponding to diopter values. Fig. 13 is an explanatory diagram that does not show the light intensity distribution state on the surface, and is an explanation of the case where the diopter value is determined from the light intensity distribution state [2
I. FIGS. 14, 15, and 16 are explanatory diagrams showing changes in the amount of light of each light beam when blocked by the light shielding member when the spread width Δ on the light shielding member is larger than 1/2 the size of the light source, Figure 17 (^) (B) (C) is a timing diagram for explaining motor control, Figure 18 is a basic horizontal diagram showing the second embodiment, Figure 19 is the DD of Figure 18. 20 is a view taken along the line E--E in FIG. 18. 1 is a projection system, 2 is a light receiving system, 3 is an eye to be examined, 4 is a light source, 5 is a half mirror, 8 is an objective lens, 9 is a light receiving element, 12 is a light shielding member, 17 is a mask plate, 2035 is a slit plate, 3
6y, 36z indicate dichroic mirrors, 31 2 2 2 2 2 2 Figure 14 Light amount Figure 15 Light amount ↑

Claims (1)

[Scope of Claims] 1) A projection system that includes a measurement light source and projects an image of the measurement light source onto the fundus of the eye to be examined, and a light flux reflected from the fundus onto a light-receiving element disposed at a substantially conjugate position with the pupil of the eye to be examined. In an eye refractive power measuring device that has a light receiving system for guiding the eye and measures the eye refractive power of the eye to be examined based on the light intensity distribution of the pupil image of the eye to be examined formed on the light receiving element, the light source is located on a plurality of meridians. a light shielding member configured to project a plurality of light beams and selectively transmitting the plurality of light beams, and providing a mask plate for selectively transmitting the plurality of light beams, and blocking a part of the reflected light beam of each of the selected light beams in the optical path of the light receiving system; An eye refractive power measuring device characterized by being provided with. 2) A projection system that includes a measurement light source and projects an image of the measurement light source onto the fundus of the eye to be examined, and a light receiving system that guides the reflected light flux from the fundus onto a light receiving element placed at a position approximately conjugate with the pupil of the eye to be examined. In an eye refractive power measuring device that measures the eye refractive power of the eye to be examined based on the light intensity distribution of the pupil image of the eye to be examined formed on the light receiving element, the light source has different wavelengths from positions on multiple meridians. a dichroic mirror configured to emit measurement light of a band, a light shielding member for blocking a part of the reflected light flux of each wavelength band in the optical path of the light receiving system, and separating the reflected light flux passing through the light shielding member into each wavelength band; An eye refractive power measuring device characterized by being provided with.