JPH0496728A - Refraction force measuring device for eye - Google Patents

Abstract

PURPOSE:To carry out the measurement for degree of astigmatism, astigmatic axis angle, etc., by installing a calculation processing part for calculating the degree of sphericity, degree of astigmatism, and astigmatic axis angle of an inspected eye on the basis of each light quantity distribution information in two directions on a light receiving element in the case where a light shielding member is arranged in a prescribed longitudinal direction and each different lateral direction. CONSTITUTION:The light projection system 1 and the light receiving system 2 of a measurement device are arranged oppositely to an inspected eye 3, and when the upper half of the light flux of a measurement light original image 4 reflected by the eye bottom is shielded by the edge part 15 of a light shielding member 12, the reflected light flux which is light-shield is projected on a light receiving surface 9a by an objective lens 8, and the illuminance of the projected image gradually increases or reduces in the direction perpendicular to the edge ridge line. The illuminance signal at a kern point in the direction perpendicular to the edge ridge line which passes through the center of the projection image among the signals supplied from a light receiving element 9 is taken out, and the light quantity distribution is calculated by a calculator 13. Besides, the light receiving element 9 in the direction parallel to the edge ridge line which passes through the center of the taken-up image and the illuminance signals at the respective points are taken out, and the light quantity distribution is calculated similarly by the calculator 13. Accordingly, the measurement of the refraction force of the eye and the measurement of astigmatizm can be realized, and the results of the measurements can be obtained instantly.

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.

[Prior Art] Conventionally, eye refractive power measurement devices include a so-called subjective ophthalmoscope that measures eye refractive power based on the response of a test subject, and a so-called autorefractometer that measures the eye to be examined objectively. The device is known.

However, when measuring infants with this type of device,
Since the infant's cooperation cannot be obtained, a subjective ophthalmoscope can only perform measurements.Also, with a general autorefractometer, the position of the eye to be examined must be fixed, but 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, the so-called 7 method involves illuminating the fundus of the eye to be examined with a strobe light, photographing the state of the light flux at the pupil of the eye with a camera, and measuring the ocular refractive power of the eye to be examined from the results.
A measurement method based on otrefraction has been proposed.

In this photorefraction method of measurement, sufficient measurements can be made even if the optical axis of the eye to be examined is slightly shifted.
This method is said to be useful for measuring the eye refractive power of infants and young children in whom it is difficult to fix the subject's eye.

However, in the photorefraction type eye refractive power measurement device, the optical axis of the camera is illuminated with a strobe light source from an oblique direction, and the pupil image at that time is simply photographed. However, there are problems in that some diopter values cannot be measured depending on the position of the light source, and the measurable range is narrow.

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.

By the way, in the earlier application, Japanese Patent Application No. 1-24491, the present applicant projected a light source image onto the fundus of the eye to be examined, and blocked the light flux from the light source reflected on the fundus with an edge-shaped light shielding member. We proposed an eye refractive power measurement device that receives a dense light beam with a light receiving element and measures the eye refractive power based on the light intensity distribution of the light beam.
Solved the problem mentioned above.

The present invention is based on the invention related to the earlier application, and aims to provide an eye refractive power measuring device capable of measuring astigmatism degree, astigmatic axis angle, etc.

[Means for Solving the Problems J] The present invention includes a projection system for projecting a light source image onto the fundus of the eye to be examined, and an edge-shaped light shielding member for blocking part of the reflected light flux from the fundus of the eye to be examined. a light-receiving system for guiding the reflected light flux from the fundus of the eye to be examined via a light-shielding member onto a light-receiving element disposed at a position substantially conjugate with the pupil of the eye to be examined; and the light-shielding member is arranged in a predetermined meridian direction with respect to the eye to be examined. information on the light intensity distribution in at least two directions on the light-receiving element when the light-receiving element is placed, and information on the light-amount distribution in at least two directions on the light-receiving element when the light shielding member is disposed in a meridian direction different from the meridian direction. It is characterized by comprising a calculation processing unit for calculating the spherical power, astigmatic power, and astigmatic axis of optometry, and further includes a projection system for projecting a light source image onto the fundus of the examinee's eye, and the examinee's eye fundus. ! It has an edge-like light shielding member that blocks part of the light flux reflected from the fundus in at least two meridian directions, and the light flux reflected from the fundus of the eye to be examined is placed at a position substantially conjugate with the pupil of the eye to be examined via the light shielding member. a light-receiving system for guiding the light onto the light-receiving element; information on the light quantity distribution in at least two directions on the light-receiving element formed by the light flux that has passed through the light-shielding member in one meridian direction; An arithmetic processing unit for calculating the spherical power, astigmatic power, and astigmatic axis of the eye to be examined based on information on the light amount distribution in at least two directions on the light receiving element formed by the light beam. It is.

U action By blocking a part of the reflected light flux from the fundus of the examined eye with the edge-shaped light shielding member, the pupil image projected onto the light receiving element has a light distribution according to the eye refractive power and a reflected light flux. It has a light amount distribution that is the sum of the light amount distribution due to astigmatism, which is unrelated to the fact that a part of the image is blocked. The light intensity distribution caused by astigmatism changes in a regulated manner with respect to the meridian angle, so by changing the arrangement of the light shielding member corresponding to at least two meridian directions and obtaining information on the light intensity distribution in at least two directions on the light receiving element, the eye to be examined can be adjusted. The spherical power, astigmatic power, and astigmatic axis can be calculated.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

The eye refractive power measurement device according to the earlier application (Japanese Patent Application No. 1-24491) uses an edge-shaped light shielding member to block the light beam from the light source that is reflected on the fundus of the eye, and receives the blocked light beam with a light-receiving element. This is used to measure refractive power, but when an obstructed light beam is received by a light receiving element, the light intensity distribution state on the light receiving element due to the effect of the interception is the eye refractive power in the direction perpendicular to the edge ridge line (meridian direction, y direction). It corresponds to By the way, astigmatism is
This is caused by the difference in eye refractive power (deopter value) at each meridian, and the state of astigmatism is specified by the degree of sphericity S, the degree of astigmatism C2, and the astigmatism axis angle A. Therefore, if the eye to be examined is a perfect sphere and there is no astigmatism, the light intensity distribution will be constant in the direction parallel to the edge ridgeline (incoming direction), and if a change in the light intensity distribution appears in the direction parallel to the edge, this light intensity distribution will be astigmatic. This is due to the influence of

Specific examples will be explained below with reference to FIGS. 1 to 3.

1 is a projection system for projecting a measurement 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 facing the eye 3 to be examined.

The projection system 1 has a slit-shaped light emitting section 4a having a required length that is perpendicular to the optical axis of the projection system and perpendicular to the edge of a light shielding member 12, which will be described later, and a measuring device that rotates in synchronization with the light shielding member 12. The projection system 1 consists of a light source 4 and a half mirror 5 for reflecting the light beam 11 from the measurement light source 4 toward the eye 3 to be examined. The light-receiving system 2 is composed of an objective lens 8 and a light-receiving element 9, and a light beam 10 from the fundus 7 passes through a half mirror 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, one side of the light beam 10 with the optical axis 0 of the objective lens 8 as a boundary is shaded at a position where a measurement light source image is formed when the eye refractive power of the eye 3 to be examined is the reference diopter value. An edge-shaped light shielding member 12 is arranged in a plane perpendicular to the optical axis.

The light shielding member 12 has an edge ridgeline 15a of an edge portion 15 aligned with the optical axis of the light receiving system 2, and is supported rotatably around the optical axis by rollers 20 and the like, and is rotated in synchronization with the measurement light source 4 as described above. It seems to rotate.

Further, a computing unit 13 is connected to the light receiving element 9, and the computing unit 3 stores data of the light receiving state of the light receiving element 9 at each ridge line in memory, performs further calculations, and outputs the result to a display 14. It has become.

The action will be explained below.

Astigmatism can be measured, for example, by measuring two meridians and the light intensity distribution in a direction perpendicular to each of the two meridians.

The edge portion 15 of the light shielding member 12 blocks the upper half of the light flux (hereinafter referred to as reflected light flux) of the measuring light developing 4 reflected at the fundus. The blocked reflected light beam is sent to the light receiving surface 9 by the objective lens 8.
a, and this projected image is perpendicular to the edge ridgeline (
The brightness gradually increases or decreases in the y-axis direction). (The direction of increase or decrease differs depending on whether the eye refractive power of the eye to be examined is larger or smaller than the reference diopter value).

Among the signals from the light-receiving element 9, brightness signals at each point passing through the center of the projected image and perpendicular to the edge ridge line (y-axis direction) are extracted, and the light amount distribution is calculated by the calculator 13.

Further, the brightness signals of each point of the light receiving element 9 passing through the center of the projected image (in the direction parallel to the edge ridge line (X-axis direction)) are taken out, and the light amount distribution is calculated in the same way by the calculator 13.

Below is the book! I1 The principle of the invention will be explained.

(1) First, consider that the eye to be examined is illuminated by a point light source. Then, a blurred elliptical light spot is generally formed on the fundus of the eye, and light from each point of this light spot is emitted from the pupil of the eye to be examined. Here, if we consider the light flux emitted from a single point on the pupil, we can form an elliptical cone-shaped light flux centered on the ray (hereinafter referred to as the central ray) that connects this point on the pupil and the center of the light spot on the fundus. (See Figure 4).

When the subject's eye has astigmatism, how the above-mentioned central ray changes depending on the refractive power of the subject's eye will be explained with reference to FIGS. 5 to 7.

In FIG. 5, X on the pupil of the subject's eye with the center of the pupil of the subject's eye as the origin and the astigmatism axis direction as the X axis.

The y-coordinate system is determined, and the coordinate system on the light source located at a distance from the pupil (coinciding with the position of the edge portion 15) is X,
In Figure 0, which is defined as the Y coordinate system, the (A> plane is the first focal plane that is conjugate with the fundus in the plane that includes the y-axis of the subject's eye and is located at a distance of h from the pupil, and the (B) plane is the subject's eye. It is assumed that the second focal plane is conjugate with the fundus in a plane including the X-axis of the optometry, and is located at a distance of 12 from the pupil.

Here, the central ray (solid line) that is emitted from a point light source (XI, Yr) and passes through the center of the pupil, and the central ray (dotted line) that is reflected at the fundus and passes through the point (xp, yp) on the pupil. Thinking 6 If we consider the central ray in a cross section including the y-axis as shown in FIG. 4, the ray passes through a constant position v1 on the first focal plane regardless of the position of y. Let v2 be the reaching height of this light beam on the second focal plane, and let Yc be the reaching height at the edge portion 15 surface. Further, as shown in FIG. 7, considering the central light beam in a cross section including the X-axis, the light beam passes through a constant position U2 on the second focal plane regardless of the position of Xp. The arrival height of this ray on the first focal plane is ul, edge part 1
Let the height reached on the 5th surface be Xc. Here, in Figure 6, from the similarity condition of the triangle formed by the solid and dotted rays and the coordinate axes, (Yr Yc)/yp = (L 1+)/I
+...(1) is obtained, and similarly from Fig. 7, (Xl-Xc)/xp = (L-12>/L...
(2) is obtained.

From these equations (1) and (2), the coordinate position of the point light source (X+Y+
) and the coordinate position (xp, yp) on the pupil, the coordinates (Xc, Yc) of the position where the central ray from the point on the pupil reaches the edge portion 15 surface are as follows: Xc = X+ + ( 1-L/12) XpYc = Y,
+(IL/lr)3'p''・(3).

Therefore, the light flux emitted from the point light source (x+, Yr) is reflected by the fundus 7 and exits from the point (XP, yp) on the pupil, on the edge portion 15 surface, at the point (Xc) determined by equation (3). , Yc), which is distributed in an elliptical manner.

(2) In the above, we considered the central ray from one point on the pupil, but next we will consider the luminous flux (hereinafter referred to as a ray band), which is a collection of central rays from each point on a predetermined meridian on the pupil. .

If we consider a meridian direction tilted by θ from the X axis on the pupil as the predetermined meridian direction, the ray band, which is the diagonally shaded surface, rotates within the optical path from the pupil to the edge portion 15, as shown in FIG. The beam reaches the edge part 15 surface, and the cross section of this ray band on the edge part 15 surface becomes a straight line with a predetermined inclination.
On this straight line, the light beams distributed in an elliptical shape centered on the above-mentioned central ray are lined up.

(3) Next, FIG. 9 shows the state of the light flux on the edge portion 15 when the point light source (XI, Yr) moves along a predetermined direction (here, a direction perpendicular to the edge ridge line 15a).

In FIG. 9, θ6 indicates the inclination angle of the edge portion 15,
α indicates the cross-sectional straight line of the ray band on the edge surface mentioned above, and as mentioned above, the elliptical light flux centered on the central ray generated by the point light source on the optical axis is lined up on this straight line, and here the pupil When the point light source moves along the Y' direction perpendicular to the edge ridge line 15a, the elliptical light flux formed around the central ray will be α along the Y' direction.
It can be seen that the range cut by the edge portion 15 differs depending on (Xc, Yc).

A collection of these light beams determines the light amount distribution on the light receiving element 9 placed at a position conjugate with the pupil of the eye to be examined.

(4) Based on the points explained above, the light amount distribution of the pupil image of the subject's eye on the light receiving element 9 will be considered.

Below, the light spots on the fundus 7 caused by each point light source are as follows:
Assume that the illuminance when illuminating the pupil is E, and that there is no difference depending on the position of the point light source. Also, the direction of the edge ridge line 15a is θ
9, and the linear light source is arranged in a direction perpendicular to the edge ridge line 15a.

First, consider a coordinate system X'-Y' obtained by rotating the aforementioned coordinate system X-Y by 06. Then, if the above-mentioned equation (3) is expressed in this coordinate system X'-Y', then, Xc = Xr CO5θA +Y+ slnθ^
+ (L L/ + 2) Xp CO3θa+
(1-L/11) yP S group θ9...(
68) Yc =-X+ S! nθA +Y+C
O3θ^ (1-L/12)XP S group θ^ + (1-L/I+) 3'p CO3θ6...(6
B). In addition, in this coordinate system x'-y', the linear light source is parallel to Y', and its coordinates are X+ = X+ CO8θA + Y+ sln
θ^Yr'=-X, s group θA+YICO5θ9...(
7).

Based on these, the light amount distribution on the light receiving element 9 at a position conjugate with the pupil, which is generated by the light flux passing through the edge portion 15, is calculated.

FIG. 10 focuses on one point on the pupil based on FIG. 9, and shows the state of the light flux from this point on the edge portion 15, and this light flux is caused by the movement of the point light source. The beam moves along the direction Y' perpendicular to the edge ridge line 15a, the coordinate Yc' of the central ray changes, and the beam moves from a state where it is completely eclipsed by the edge part 15 to a position far away from the edge part. It turns out.

For the sake of explanation below, let us assume that the inclination of the elliptical beam is θ^ (indicating the astigmatic axis of the subject's eye), and consider the state in which the elliptical beam touches the edge ridge line 15a, and the distance between the edge ridge line 15a and the center ray at this time. Let be R<θA).

Here, the light 1 distribution f(Xp+y,) in the pupil image on the light receiving element generated by the light flux passing through the edge portion 15 is the above (3
), and the coordinate system X'-Y
' can be shown by the following integral formula.

Here, φ is the cross-sectional area of the elliptical light beam, Δφ is the cross-sectional area of the light beam that is not eclipsed by the edge portion 15, and E is a constant.
Integration is performed within the range of the linear light source 4.

f(xt, 3's) =E//[Δφ/φ] dY+' dX+...
(8) Here, with respect to the movement of X1', the proportion of the luminous flux that is affected by C does not change, so if the light source is a rectangle, the above equation (8) becomes f(xt, yp) 2EH,/"[ Δφ/φ]dY+ (9).

Let us consider the integral of equation (9) above by dividing it into ranges.

The range where the luminous flux is partially eclipsed by the edge portion 15, i.e. -R
The integral value at (θe)≦Yc′≦R(θA) is 2EHOR(θA) due to symmetry.

From formula (6B), the integral value in the range where the luminous flux is not eclipsed at all, that is, Yc'≧R(θA), is Y
r (LL/12)XP S group θ^+(
1-L/1+) yp cosθ, ≧R(θA)Io
From ≦Y+'≦I0, the value in this range of equation (9) is 2EHo (Io (I L/12 )Xp
Slnθ6+ (1-L/II) yp C03
oA −R(θ, )) (11) In the range where the luminous flux is completely eclipsed, that is, Yc′≦−R(θA), the value of equation (9) in this range is zero.

f (xp, y, ) = O - (12) Therefore, f (XP, yP) = Equation (10) 10 Equation (ii) - 2
EHo (Io-(1-L/12)XP si
nθ.

+(1-L/I+) 3'p CO3θ9)...
(13) Therefore, from equation (13), f (Xp, y
Since p ) is a linear expression of Xp and yp, the light amount distribution shows an inclined plane distribution.

Further, the light amount at the center coordinates (0, O) of the pupil is equal to the average value of the entire pupil light amount expressed by equation (14).

f (0,0) = (//f (xt, yp)dxp dyp
>1/πP2...(14) The light intensity distribution normalized by f (0, O) is expressed as fS(xp
lyp), fs(xp, yp) t(xp, yp)/f(0,0)=(Io
(IL/L) Xp S! nθ^+ (
1-L/1+) 3'p CO3θA l/I
o - (15).

Next, θ3 in equation (15) is the direction of the edge portion 15 (X'
It represents the direction of the astigmatism axis measured from the
Consider the '-Y' coordinate as a reference (device coordinate).

When a pupil image is captured by rotating the edge portion 15 by an angle θ from the
θ, −θ), and the pupil coordinate is
-Y' axis direction and set it as Xp'-yp' coordinate, XP = Xp CO8θA -yp Sinθ
^y, =x, sinθA yp' CO
3θA ・(16) Therefore, from equation (15), fs (xp, 'ip') = fIo + (at CO3θ + at Sinθ) xp
し(at sinθ+a, cosθ)3'p'l/I.

...(17) However, al = L ((1/12-1/II) 5in2θA
)/2...(18^) a2=L (2/L-(1/I,-)-1/12)+
(1/It -1/12)CO32θ6)/2...
・(18B) as = l, (2/L (1/li +1/12)
-(1/1.-1/12)CO32θ9)/2...
(18C) Therefore, pupil images are captured at two or more different angles θ, and the following quantity, which is the component of the gradient of each light intensity distribution fs (Xp, 3'p') in the direction of the XP13/P' coordinate axis, fS(xp, yp')/? xp=(a+c
osθ10a2S! nθ)/IO・, −(19)afs(
xp, yp')/ayp=(al sin
θ0as CO8θ) / 1. −(20) as the angle θ
4 for the unknowns a1, a2, and a3.
Since three equations are obtained, the above a I , a 2, a
s can be determined.

The spherical power S, the astigmatic power C1, and the astigmatic axis A are S=1/1.
．． , C=1/12-1/I, , A=θ^, so it is expressed as formula (18A) (18B) (18C)% formula % When al , at , and as are determined, the above formula Accordingly, the spherical power S, the astigmatic power C1, and the astigmatic axis A can be calculated, and the state of the astigmatic eye can be measured.

When the eye to be examined has only spherical power, it can be seen from equations (18A), %, and equations (19) and (20) that the gradient of the light amount is always in the direction perpendicular to the edge ridge line 15a.

In the above explanation, the center of the pupil and the rotation axis of the light shielding member 12 are on the same straight line, but the invention is not limited to this, and the imaging optical system and the visual axis do not need to be on the straight line either. do not have.

The arithmetic unit 13 calculates not only the eye refractive power but also the spherical power S,
Calculate astigmatism power C1 astigmatism axis A and display the result H14
to be displayed.

Note that various configurations are possible for measuring the light amount distribution in the X-axis direction and the y-axis direction at two positions with different edges.

11 to 13 show a second embodiment.

A rectangular hole is bored in the light shielding member 17, and the four sides of the core are edge ridgelines 15a, 75b, 15c, and 15d, and the light source 16 also has the ridgelines 15a, 15b, 15c,
Slit-shaped light emitting parts 16a and 16b corresponding to 15d
, 16c, and 16d are provided.

Select two of the light emitting parts 16a, 16b, 16c, and 16d, excluding those on the same meridian, turn them on one by one, and measure the light intensity distribution in the directions perpendicular and parallel to the edge ridge line in the same way as above. By determining the inclination angle of the light amount distribution, the spherical power S, the astigmatic power C2, and the astigmatic axis A can be calculated.

Furthermore, by sequentially lighting up all the light-emitting parts 16a, 16b, 16c, and 16d, and then averaging the measurement results along the same meridian, measurement errors due to the effects of pine hair, turbidity of the crystal zone, etc. can be eliminated. It is possible to improve measurement accuracy. Also, when using an LED etc. for the light emitting part, 1
If lights 6a, 16c, 16b, and 16d are turned on in this order, the time difference in data acquisition in the same meridian direction can be reduced.

Further, FIGS. 14 and 15 show a third embodiment,
This embodiment has the same configuration as the light source 16 shown in the second embodiment, and each light source section 16a.

16b... has a light source 16' that does not blink, and a light shielding member 17 that is the same as that shown in the second embodiment, and each light source section is provided between the light shielding member 17 and the objective lens 8. A beam separating means, for example, a deflection prism 19, is provided to separate the beams from the light receiving system 2 from the optical axis, that is, to separate them in a direction away from the optical axis.

The deflection prism 19 includes each light source section 16a, 16b...
Prism pieces 19a19tl corresponding to the above are assembled radially around the optical axis.

In this embodiment, since the light beams from the respective light source sections 16a, 16b, etc. are projected onto different positions on the light receiving surface 9a, the scene distribution is determined in the same manner as described above at each projected portion of the light receiving surface 9a. By determining the above, the light intensity distribution in a plurality of meridian directions can be determined at the same time, and the degree of sphericity S, the astigmatic power C1, and the astigmatic axis angle A can also be determined at the same time.

Furthermore, FIG. 16 shows a fourth embodiment.

A light source 4 is disposed at a position facing the eye 3 to be examined, and the light receiving systems 2x and 2y having optical axes that intersect with the optical axis in a plane including the light source 4 and the optical axis of the eye 3 to be examined are connected to the eye 3 to be examined. Arrange sequentially from the side. Therefore, a half mirror 5x is placed on the optical axis of the eye 3 to be examined.
, 5y are arranged, and the light flux from the fundus 7 is sent to the light receiving system 2x, 2y.
Split reflection towards.

Here, the light-receiving surfaces 9xa and 9ya of the light-receiving elements 9x and 9y of the light-receiving systems 2x and 2y are the objective lenses 8x and 9ya as in the previous embodiment.
, 8y is a conjugate position with the pupil 6 of the subject's eye 3, and the 2
The light shielding members 12x and 12y are placed in the optical paths of the two light receiving systems 2x and 2y at the same positions as in the embodiment described above, and the light shielding member 12Y is positioned at a position rotated by 90 degrees from the light shielding member 12X with respect to the optical axis.

With such a configuration, the light amount distribution obtained from the light reception results of the light receiving elements 9x and 9y becomes a value related to two meridian directions, and can be measured simultaneously.

In the embodiment shown in FIG. 16, the light receiving systems 2x, 2
y have exactly the same configuration, the direction of split reflection by the half mirror is changed by 90 degrees with respect to the optical axis of the eye to be examined 3, and the light receiving system 2x
, 2y are arranged radially with respect to the optical axis of the eye 3 to be examined, it is possible to similarly obtain the light amount distribution inclination angle in the two meridian directions.

In addition, in the first, second, third, and fourth embodiments described above, in order to identify the astigmatism state, it is sufficient to obtain the light intensity distribution for two meridians, but the scene distribution for three or more meridians can be determined for each meridian. If the values are determined and averaged, the measurement accuracy will be further improved.

In the above embodiment, a half mirror was used as the beam separating means of the projection system, but it goes without saying that various beam separating means such as a beam splitter 5 and a polarizing prism may be used.

Furthermore, in the above embodiment, the necessary information is extracted from the light intensity distribution in the direction perpendicular to the edge ridgeline and the light intensity distribution in parallel, or it is of course possible to obtain information for specifying the astigmatism state even in any two directions. can.

U Effects of the invention As described above, according to the present invention, it is possible to measure not only eye refractive power but also astigmatism, and since the light receiving system uses a light receiving element, measurement results can be obtained instantly. It has a great effect.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram showing the first embodiment of the present invention;
The figures are a view taken along the line A-A in FIG. 1, FIG. 3 is a view taken along the line B-B in FIG. Figures 6 and 7 are explanatory diagrams showing the state of reflected light from the fundus when the eye to be examined has astigmatism, respectively. Figure 8 is an explanatory diagram showing the twisting of the reflected light beam, and Figure 9 is a shading diagram. An explanatory diagram showing the state of the reflected light flux on the member, FIG. 10 is an explanatory diagram showing the relationship between the reflected light flux on a line perpendicular to the edge ridgeline and the edge member, and FIG. 11 is a basic diagram showing the second embodiment. The configuration diagram, Figure 12 is a view taken along the line C-C in Figure 11, and Figure 13.
The figure is a view taken along the line DD in FIG. 11, FIG. 14 is a basic configuration diagram showing the third embodiment, and FIG. 15 is a view taken along the line EE in FIG. 14.
FIG. 16 is a basic configuration diagram showing the fourth embodiment. 1 is the projection system, 2.2x, 2y is the light receiving system, 3 is the eye to be examined,
4.16.16' is a light source, 5, 5x, 5y are half mirrors, 8, 8x, 8y are objective lenses, 9.9x, 9y are light receiving elements, 12, 12X, 12y, 17 is a light shielding member, 1
9 indicates a deflection prism. Patent applicant Dobcon Co., Ltd.

Claims (1)

[Scope of Claims] 1) A projection system for projecting a light source image onto the fundus of the eye to be examined, and an edge-shaped light shielding member for blocking a part of the reflected light flux from the fundus of the eye to be examined; a light-receiving system for guiding the reflected light flux from the fundus of the eye to be examined onto a light-receiving element placed at a position substantially conjugate with the pupil of the eye to be examined; and a light-receiving element when the light shielding member is placed in a predetermined meridian direction with respect to the eye to be examined. The spherical dioptric power of the eye to be examined is determined based on each light amount distribution information in at least two directions above and each light amount distribution information in at least two directions on the light receiving element when the light shielding member is arranged in a meridian direction different from the meridian direction. An eye refractive power measuring device characterized by comprising a calculation processing unit for calculating an astigmatic power and an astigmatic axis. 2) It has a projection system for projecting a light source image onto the fundus of the subject's eye, and an edge-shaped light shielding member that blocks part of the reflected light flux from the fundus of the subject's eye in at least two meridian directions, and a light receiving system for guiding the reflected light flux from the fundus of the subject's eye onto a light receiving element disposed at a position substantially conjugate with the pupil of the subject's eye, and at least one on the light receiving element formed by the light flux transmitted through the light shielding member in one meridian direction. Based on each light amount distribution information in two directions and each light amount distribution information in at least two directions on the light receiving element formed by the light flux transmitted through the light shielding member in the other meridian direction, the spherical power, astigmatic power, and astigmatism of the eye to be examined are determined. An eye refractive power measuring device characterized by comprising a calculation processing section for calculating an axis.