JP2817798B2 - Eye refractive power measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eye refractive power measuring device, and more particularly to an eye refractive power measuring device useful for children to infants.

[Prior Art] Conventionally, as an eye refractive power measuring device, there are a so-called subjective ophthalmoscope for measuring eye refractive power based on a response of a subject, a so-called auto-refractometer for objectively measuring an eye to be examined, and the like. Devices are known.

However, when measuring infants with this kind of device, it is not possible to measure with a subjective ophthalmoscope because of the lack of cooperation of infants, and the position of the eye to be examined must be fixed with a general auto-refractometer. However, in the case of infants, it is difficult to fix the position of the eye to be examined, and the measurement is extremely difficult.

In order to eliminate these drawbacks, a so-called photorefraction method is used in which the fundus of the subject's eye is illuminated with strobe light, the state of the luminous flux at the pupil of the subject's eye is photographed with a camera, and the eye refractive power of the subject's eye is measured from the result. Measurement methods have been proposed.

In this photorefraction method measurement, it is possible to measure sufficiently even if the optical axis of the eye to be examined is slightly shifted, and it is useful for measuring the eye refractive power of infants who have difficulty fixing the eye to be examined. It is supposed to be.

[Problems to be Solved by the Invention] However, in such a photorefraction type eye refractive power measuring apparatus, a strobe light source illuminates the optical axis of a camera from an oblique direction, and a pupil image at that time is simply taken. There is a problem that there is a diopter value that cannot be measured depending on the position of the light source, and that the measurable range is narrow.

Further, in this type of apparatus, measurement of astigmatism such as astigmatism degree and astigmatic axis angle has not been taken into consideration.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an eye-refractive-power measuring apparatus capable of obtaining a measurement result instantaneously and measuring an astigmatic degree, an astigmatic axis angle, and the like.

Means for Solving the Problems The present invention has a measurement light source, and a projection system for projecting a measurement light source image on the fundus of the eye to be inspected, and a fundus on a light receiving element arranged at a position substantially conjugate with the pupil of the eye to be inspected. And a light receiving system for guiding a reflected light flux from the eye refractive power measuring apparatus for measuring the eye refractive power of the eye to be examined from the light amount distribution of the pupil image of the eye to be examined formed on the light receiving element, A light source is configured to project a light beam from a plurality of meridians, and a mask plate is provided to select and transmit the plurality of light beams, and a part of a reflected light beam of each of the selected light beams in an optical path of the light receiving system. And a projection system for projecting a measurement light source image to the fundus of the eye to be examined, further comprising a side constant light source, and substantially conjugate with the pupil of the eye to be examined. And a light receiving system for guiding the reflected light flux from the fundus on the light receiving element arranged at the position In an eye-refractive-power measuring apparatus that measures the refractive power of an eye to be inspected from a light quantity distribution of a pupil image of the eye to be inspected formed on a light receiving element, the light source is a plurality of measurement lights in wavelength bands different from positions on a plurality of meridians. Is provided, and an edge-shaped light shielding member that shields a part of the reflected light beam of each wavelength body is provided in the optical path of the light receiving system, and the reflected light beam that has passed through the edge light shielding member is separated for each wavelength band. A dichroic mirror is provided.

[Operation] The state of blocking the light beam by the light blocking member differs depending on the difference in the eye refractive power of the eye to be examined. The light-shielded state corresponds to the eye refractive power, and the eye refractive power can be measured based on the state of the light beam projected on the light receiving element, that is, the light amount distribution. In addition, the astigmatism state can be specified by measuring the eye refractive power on a plurality of meridians. In the first invention, the light amount distribution of the plurality of meridians is temporally separated and measured. In the second invention, the measurement light flux is measured. Separate into different wavelengths and measure each.

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

Astigmatism is caused by a difference in eye refractive power (diopter value) at each meridian, and the state of astigmatism can be specified by measuring the sphericity S, the astigmatic degree C, and the astigmatic axis angle A. Further, Deoputa value D _theta and the spherical degree S at meridian arbitrary angle theta, astigmatic degree C, the relationship between the astigmatic axis angle A is represented by the following formula.

D _θ = S + C sin (θ−A) (1) Accordingly, if the diopter values of the three meridians θ ₁ , θ ₂ , and θ ₃ are obtained, the spherical power S, the astigmatic power S, and the astigmatic axis angle A are obtained. The state can be specified.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

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

The projection system 1 includes a light source 4, a half mirror 5 for reflecting a light beam 11 from the light source 4 toward the subject's eye 3, and a flare preventing device 28 disposed on the opposite side of the half mirror 5 from the light source. The projection system 1 projects a light beam 11 from the light source 4 through the pupil 6 onto the fundus 7 so as to form an image of the light source 4.

The light source 4 includes a light emitter 15 having a tungsten filament, an infrared filter 16, a mask plate 17, a condenser lens 18 such as a Fresnel lens, a diffusion plate 19, and a slit plate 20. The mask plate 17 is rotatably supported, and is provided with a light projecting window 21 that is widened toward the outer periphery on a required meridian. The mask plate 17 is rotated at a predetermined speed by a motor 22 as described later.

The slit plate 20 is located on six meridians equally dividing the center, and the slit holes 20a, 20b, 20c, which become wider toward the outer peripheral side,
20d, 20e, 20f are drilled. The flare preventer 28 will be described. A plurality of strip-shaped absorption plates 23 are arranged in parallel with each other in a posture in which the surface is inclined with respect to the optical axis of the projection system 1.
The absorption wall 24 is provided on the side opposite to the half mirror 5. Absorbing wall
Reference numeral 24 may be an inner surface of a lens barrel that houses the optical system.

An antireflection coat or a black antireflection paint is applied to both surfaces of the absorption plate 23 and the absorption wall 24.

The anti-flare device 28 attenuates the light from the light source 4 transmitted through the half mirror 5 by reflecting the light on the absorbing plate 23 and the absorbing wall 24 a plurality of times, and receives the light transmitted through the half mirror 5 by the light receiving system 3. To prevent it from being done.

The light receiving system 2 includes an objective lens 8 and a light receiving element 9, and a light beam 10 from the fundus 7 passes through the half mirror 5 and is guided onto the light receiving element 9.

The light receiving element 9 is an area CCD, an image pickup tube, or an aggregate of two or more light receiving elements. The light receiving surface 9a of the light receiving element 9 is disposed at a position conjugate with the pupil 6 of the eye 3 with respect to the objective lens 8.

In the optical path of the light receiving system 2, at a position where a light source image is formed when the eye refractive power of the eye 3 to be examined is a reference diopter value,
An edge-shaped light blocking member 12 for blocking one side of the light beam 10 with the optical axis O of the objective lens 8 as a boundary is disposed in a plane perpendicular to the optical axis.

The light shielding member 12 has edge-like ridgelines 25a, 25b, 25c,... Orthogonal to the meridians of the slit holes 20a, 20b, 20c,.
A square transmission hole 25 is formed.

Also, a video camera 26 in which the light receiving element 9 is incorporated.
The controller 27 extracts a signal from the light receiving element 9 by the control unit 27 and inputs the signal to the arithmetic unit 13 together with a video synchronization signal as a video signal for video.

The arithmetic unit 13 calculates the light receiving state of the light receiving element 9 based on the video signal, calculates the eye refractive power and the astigmatic state based on the light receiving state, and outputs the result to the display 14.

Further, the arithmetic unit 13 determines the rotation speed of the mask plate 17 of the light source 4 and
In order to synchronize with the video signal, the motor 22 is
The speed is controlled through. Reference numeral 30 denotes an encoder for detecting the rotation of the motor.

For the mask plate 17, a Hall element 31 is provided,
Further, a minute magnet 32 for speed detection and a minute magnet 33 for position detection corresponding to the slit position are perforated on the mask plate 17, and the Hall element 31 detects the minute magnets 32 and 33, and outputs a signal of the minute magnets 32 and 33. The data is input to the arithmetic unit 13.

 The operation will be described below.

As mentioned above, the measurement of astigmatism can be obtained by measuring the diopter value of three meridians. First, the measurement of the diopter value of one meridian will be described with reference to FIGS.

In the following description, it is assumed that the light projecting window 21 matches one of the slit holes, for example, 20a, and that the light beam is blocked by the edge-like ridgeline 25a of the light shielding member 12.

As shown in FIG. 5A, when the diopter value of the subject's eye 3 is a negative diopter value 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 causes Considering a light beam 10 reflected at one point on the optical axis among the illuminated eyelets 7, the light beam 10 is condensed in front of the light shielding member 12, that is, on the side of the subject's eye 3, and is reflected by the objective lens 8. The upper half (hatched portion) of the light beam projected on the light receiving element 9 is shielded. On the other hand, as shown in FIG. 5B, when the diopter value of the subject's eye is the reference diopter value,
Is focused on the light shielding member 12, and the light flux 10 is a light shielding member.
Unobstructed by 12.

As shown in FIG. 5 (C), when the diopter value of the eye 3 is more positive than the reference diopter value, the image of the light source 4 is projected so as to form an image behind the fundus 7, and as described above. Similarly, the light beam 10 reflected by the fundus 7 is collected behind the light blocking member 12, that is, on the light receiving element 9 side, and the light beam 10 projected on the light receiving element 9 is a portion opposite to that of FIG. The light flux (the upper half in the figure) is shielded.

Thus, the light flux projected on the light receiving surface 9a changes its light quantity distribution state with respect to the reference diopter value depending on the magnitude of the diopter value of the eye to be inspected 3 and the sign thereof, and the diopter value is determined based on this light quantity distribution state.

The light receiving element 9 is for detecting the light amount distribution of the light beam formed on the light receiving surface 9a, and the arithmetic unit 13 is configured to detect the light amount distribution of the light beam formed on the light receiving surface 9a based on the signal from the light receiving element 9. Detects the light amount distribution, determines whether the eye refractive power of the subject's eye is positive or negative with respect to the reference diopter value, calculates the absolute value, outputs the calculation result to the display 14, and the display 14 calculates Display the results.

In the above embodiment, a half mirror is used as a light beam separating means. However, it is a matter of course that various light beam separating means such as a beam splitter and a polarizing prism are used.

In the following, with reference to FIGS. 6 (A) to 6 (E), a description will be given of the light amount distribution state of the light beam formed on the light receiving surface 9a.

In order to simplify the description in FIGS. 6 (A) to 6 (E), the optical axis of the light source 4 and the optical axis of the light receiving system are matched, and the light shielding member 12 and the objective lens 8 are matched. I have. For this reason, the light source 4 and the objective lens 8 are shown superimposed at the same position, and the light shielding member 12 is omitted.

Figure 6 (A) ~ (E) light receiving surface shows a case where the refractive power D of the eye is negative with respect to the reference power D _0, the following description by all objective lens 8 reflected light beam from the fundus It shall be projected on 9a.

Assuming that the distance between the light source 4 and the pupil 6 of the subject's eye is set to 1 and the refractive power of the subject's eye at which the image of this light source is focused on the fundus is the reference refractive power D ₀ It is.

FIG. 6A shows a case where the refractive power of the eye to be inspected is D (<D ₀ ) from one point S ₀ on the axis of the light source 4 on the slit having a length L in the direction perpendicular to the optical axis. Indicates the projected light flux,
The image of the point S ₀ is once formed on S ₀ ′,
Projected as a blurred image. Region 7a where D ₀ -D is projected in accordance with increase becomes wider.

FIG. 6B shows the state of the light beam 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 luminous flux from the point I- _n at the end of the projection area on the fundus 7 of the eye to be inspected, the image I- _n 'of this point is considered.
Is imaged at a position 1 'away 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 arranged at a position conjugate with the pupil 6 of the eye to be examined. The relational expression between l 'and the refractive power D of the eye to be examined is as follows.

On the other hand, when the pupil diameter of the eye to be examined is u, the spread width Δ of the light beam emitted from one point on the fundus on the edge is as shown in FIG. From the equations (1) and (2). Thus, as the difference between the refractive power D of the eye 3 to be examined and the reference refractive power D ₀ increases, the spread on the light shielding member 12 increases.

Next, the spread of the light beam on the light receiving element 9 will be described. The light receiving element 9 is always irrespective of the refractive power of the eye 3 to be inspected.
Assuming that the diameter of the pupil 6 of the eye to be examined is u and the magnification of the objective lens 8 is β, the region of the diameter of βu on the light receiving element 9 (the refractive power of the eye to be examined) Is unaffected by the light beam.

Further, after the imaging from the light beam is similarly examined eye pupil 6 'image I _n to the position of' l from the I _-n symmetrical point I _n with respect to the optical axis, the same area on the light receiving element 9 projected onto βu. Light source 4
As a point light source, when that there is no light blocking member 12 is, those points I _-n from these fundus _{7, ... I 0, ... I} n, the integral of the light beam from determining the light intensity distribution on the light receiving element 9 It is.

Here, in order to consider the light amount distribution on the light receiving element 9, the light flux incident on the end position P _-n of the light beam projection position on the light receiving element 9, that is, the coordinate position -βu / 2 centered on the optical axis. Considering the above, the light beam incident on this position is limited to the light beam in the range of the oblique line A in FIG. 6 (C).
Similarly, considering the light flux incident on the position _Pn symmetrical to the P- _n position with respect to the optical axis, the light flux is limited to the light flux in the range of the hatched line A '. When an edge-shaped light-blocking member 12 that blocks one light beam A ′ of the optical axis is arranged at a distance of 1 from the pupil 6 of the eye to be examined (a position conjugate with the light source 4), P ₋ light beam incident on the position of the _n is not blocked by the light shielding member 12, the light beam toward the upper position from the position of the P _-n is gradually shading, half of the light beam is blocked by the center P ₀ position, P _n In this position, all the light beams are blocked. Therefore, the edge-shaped light shielding member 12
As a result, the light becomes darker on the light receiving element 9 as it goes upward, and the light quantity distribution has a constant slope where the light quantity becomes 0 at the point _Pn .

6 (A) to 6 (C) show only a light beam emitted from one point on the optical axis of the light source 4, but one point S- _n at the end of the light source 4 (L is the size of the light source) Considering the luminous flux from the point (-L / 2 coordinate position), the result is as shown in FIG. 6D. Light beam from the point S _-n are projected from I _-n point on the fundus 7, as shown in FIG. 6 (D) in the region of I _n points,
The I _-n point, the reflected light from I _n points, after forming an image of, I _n '' I _n at a distance of 'l from the eye pupil 6 in the same manner as described above, the light receiving element 9 on Is projected onto a region having a diameter of βu. Here, of the luminous fluxes emitted from the point S- _n at the end of the light source 4, the luminous flux incident on the end position P- _n of the luminous flux projection on the light receiving element is the luminous flux in the shaded area B in FIG. 6 (D). It is what becomes.

Further, the S consider the light beam from one point S _n of the point symmetrical with the light source 4 _-n, of which Figure 6 given the light beam incident on the point P _-n on the light receiving element 9 C of (E) It becomes the light flux in the shaded area. As described above, when the light source 4 is considered to have a certain size, the amount of light at one point on the light receiving element 9 must be considered as the sum of the light flux from each point of the light source 4.

FIG. 7 (A) shows the respective light beams incident on the position P- _n on the light receiving element 9 based on this concept, and shows the light beams emitted from the position S- _n on the light source. Of which P _-n
Is incident on the area B (FIG. 6 (D)).
), The light beam also moves upward as the position on the light source goes upward, and at the light source position S ₀ on the axis, it becomes a light beam in the area A (see FIG. 6 (C)), the light beam C region at the position of S _n (see FIG. 6 (E)). Therefore, the light quantity at the point P- _n on the light receiving element 9 can be considered as the sum of these light fluxes.

Here, FIG. 7A is a schematic diagram showing the light quantity at the point P- _n on the light receiving element 9 when the light shielding member 12 is arranged at a position of a distance 1 from the pupil 6 of the eye to be examined. FIG. 7A shows how the light beam is blocked by the light blocking member 12 as the position on the light source changes. In FIG. 7B, the horizontal axis represents the coordinate position on the light source, and the vertical axis represents the light amount. Considering the light flux from each point on the light source, -L / 2 (L is the light source The luminous flux from the (point) point to the 0 point is not blocked by the light blocking member 12, but is gradually blocked after the 0 point of the coordinate position, and all the luminous flux is blocked at the position of Δ (the spread of the luminous flux described above). It will be. Here, FIG. 7 (B) shows the contribution of the light amount from each point on the light source, where k is the light amount from each point on the light source in the case where the light is not shielded. This corresponds to the light amount value at the point P- _n . This area value T is as follows.

Similarly, other points on the light receiving element will be considered. Figure 8 (A) have the meanings indicated in the same manner as Figure 7 the light beam incident on the center point P ₀ on the light receiving element (A), an inner P of the light beam from a point S _-n on the light source _The light flux incident on the point _{0 is} a shaded area of B ₀ , the light flux from the point S ₀ on the light source is the shaded area of A ₀ , and the light flux from the point S _n on the light source is the light flux of the shaded area C _0. is intended, the amount of light incident on the center of the light receiving element 9 will correspond to the area T ₀ of the hatched region of the Figure the 8 (B). That is, considering the light flux incident on the center point of the light receiving element from each point of the light source, -Δ /
The luminous flux is not blocked until the position of 2, and after passing the -Δ / 2 position, the luminous flux is gradually blocked, and all the luminous flux is blocked at the position of Δ / 2. The following values are calculated.

Similarly, FIGS. 9 (A) and 9 (B) show the state of the light beam incident on the point _Pn on the light receiving element and the light amount value at this point. FIG. 9 (A), the hatched A "is the light beam incident on the point of the inner P _n of the light beam from the point S _-n on the light source is shaded region of B ', the center point S ₀ on the light source The luminous flux from the point P- _n on the area and the light source is shown as a luminous flux in the hatched area C ". In this case, as shown in FIG. 9 (B), considering the light flux incident from each point of the light source to the point P _n of the light receiving element,
From the position of -L / 2 on the light source to the position of -Δ, the light beam is not blocked, and after passing the -Δ position, the light beam is gradually blocked, and all the light beams are blocked at the position of 0, When this area value is calculated, the following value is obtained.

As can be seen from the results of these equations (6), (7), and (8), the light amount value on the light receiving element 9 gradually decreases as going upward from below. The light intensity distribution on the element changes linearly as shown in FIG.

In the above description, the description has been made on the assumption that the spread width Δ on the light blocking member 12 when considering the light flux emitted from one point of the fundus is smaller than 1/2 of the size L of the light source. It is.

However In other words, when the deviation ΔD of the diopter value of the subject's eye with respect to the reference diopter value D ₀ is equal to or larger than a predetermined amount,
A linear change as shown in the figure is not shown. This will be described with reference to FIGS. 7 and 8. As aforementioned In the case of FIG. 7, FIGS. 7 (B), 8 (B), and 9 (B) are as shown in FIGS. 14, 15, and 16, respectively. It does not show a linear change as shown in FIG.

Next, when the refractive power of the eye to be examined shown in FIG. 5B is a reference value, and when the refractive power of the eye to be examined shown in FIG. The light amount distribution on the light receiving element 9 can be considered. In this case, when the refractive power of the eye to be examined is a reference value, as shown in FIG. The distribution is opposite to that shown in FIG.

The diopter value (refractive power) is the slope of the light amount distribution described above.
And the direction of the slope represents the sign of the diopter value. This will be described below with reference to FIG.

The slope of the light distribution Is defined as The spread Δ of the light beam, that is, the amount of blur Δ, is given by the above equation (5). Therefore, from equation (7) Thus, equation (11) gives the deviation ΔD of the diopter value of the subject's eye with respect to the reference diopter value D ₀ . Are proportional. Therefore, from the light intensity distribution To obtain the deviation ΔD of the diopter value of the subject's eye.
Can be obtained. Therefore, the diopter value D of the subject's eye can be obtained by the following equation.

D = D _o + ΔD (12) Although the diopter value for one meridian can be obtained as described above, the diopter value for the other two meridians is obtained by rotating the mask plate and setting the position of the mask plate to 60, for example.
{Next, when it reaches 120}, the light beam from the light source 4
The second edge-shaped ridge lines 25b, 25c,...

That is, three slit holes of the slit plate 20 and three edge-shaped ridge lines of the light shielding member 12 are selected, and a diopter value at each position is measured. As a result, the spherical power S, the astigmatic power C, The astigmatic axis angle A is immediately determined.

Next, using FIGS. 17 (A), (B) and (C) together, the motor
The speed control of No. 22 will be described.

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

It is obtained by scanning the image signal or light receiving state of the light receiving element 9 on the light receiving surface 9a and associating the light / electrically changed signal at each point with the position of each point. The scanning is divided into an odd number and an even number, and each scan is started by a synchronization signal (hereinafter, video signal) disclosed by the scan. Therefore, 1
In order to obtain a signal for a screen (one frame), two video signals are emitted, and these video signals are equally spaced in time.

The motor speed control described below is such that the number of transmissions of the speed detection signal from the Hall element 31 becomes a predetermined value based on the video signal.

17 (A), 17 (B) and 17 (C), the upper part shows a video signal, and the lower part shows a speed detection pulse signal.

When the motor 22 starts to rotate, the number of rotations is low, and the speed detection pulse is smaller than a predetermined value for the video signal corresponding to one frame (8 frames per pulse in the figure). Therefore, the computing unit 13 issues a command to the driving unit 29 to increase the speed. The drive unit 29 is driven by the motor
The speed of the motor 22 is increased, and whether or not the speed of the motor 22 matches the command is monitored based on a signal from the encoder 30.

When the speed of the motor 22 reaches a predetermined value, the rotation positions of the video signal and the mask plate 20 are synchronized. This is to ensure that the captured image signal is in a state where a part of the light beam is accurately shielded by the light shielding member 12 when the image signal is captured.

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

The computing unit 13 calculates the time difference of Δt, and performs speed control so that Δt is eliminated. Various methods of speed control are conceivable. For example, the pulse interval for driving the motor is reduced (increased speed) for a predetermined time from the time of synchronization, and the next video signal or the next video signal is used. At this time, the aforementioned Δt is set to zero.

When the video signal and the speed and rotation position of the mask plate 20 are synchronized, the position detecting magnet is
When 32 detection signals are input, the image signal for one frame at that time is taken in, the light amount distribution described above is obtained from the image signal, and the eye refractive power and the astigmatic state are measured.

The position detection signal from the Hall element 31 is
Since it is emitted corresponding to a, 20b, 20c,..., data at three meridians and six places can be measured.

Incidentally, the slit holes 20a, 20b, 20c..., And the light projecting window 21 have a so-called elongated trapezoidal shape (each end face is preferably a curved line). This is because the measurement measures a light amount distribution.
This is for equalizing the light amount on the center side and the peripheral side.

Next, a second embodiment will be described with reference to FIGS.

In FIG. 18, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

In the second embodiment, the light source 4 is composed of the light emitter 15, the diffusion plate 19, and the slit plate 35 which also serves as a wavelength selection filter.

The slit plate 35 is provided on a transparent plate made of glass or the like on a meridian in which slit windows 35a, 35b and 35c corresponding to the slit holes are equally divided into three at the center, and the other portions are opaque. Next, each slit window 35a, 35b, 35c is coated, the slit window 35c is a filter that transmits 880 to 920 nm wavelength, the slit window 35b is a filter that transmits only 840 to 880 nm wavelength, and the slit window is 35a is a filter that transmits only the wavelength of 880 to 840 nm.

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

Next, the two dichroic mirrors 36y and 36z are arranged on the reflected light member 12 side of the objective lens 8 in different directions of reflection. One dichroic mirror 36y reflects only the wavelength of 880-920 nm, and the other dichroic mirror 36y
z reflects only the wavelength of 840 to 880 nm.

The light receiving element 9x is arranged to receive the light transmitted through the dichroic mirrors 9y and 9z, the light receiving element 9y is arranged to receive the light reflected by the dichroic mirror 9y, and the light receiving element 9z is arranged to receive the light reflected by the dichroic mirror 9z. Needless to say, the light receiving surfaces of these light receiving elements 9x, 9y, 9z are arranged at positions conjugate with the pupil 6 of the eye 3 to be examined with respect to the objective lens 8.

In this embodiment, the light receiving element 9x receives the reflected light flux of only 800 to 840 nm, which is shielded by the edge-like ridgeline 25a, and the light amount distribution by the light flux is obtained.
Receives reflected light of only 840-880 nm shielded by 25b,
The light receiving element 9z is 880 to 920 nm which is shielded from light by the edge-like ridgeline 25c.
, And light amount distributions with different meridian positions are obtained.

The arithmetic unit 13 can determine the eye refractive power in the three meridian directions from these three types of light amount distributions, and can further measure the astigmatic state.

Note that the above-described wavelength selection is an example, and it goes without saying that various selections can be made as long as they do not interfere with each other.

[Effects of the Invention] As described above, according to the present invention, diopter values for a plurality of meridians can be measured, measurement for astigmatism is realized, and the light receiving system uses a light receiving element. It has an excellent effect of being obtained.

[Brief description of the drawings]

FIG. 1 is a basic structural diagram showing a first embodiment of the present invention, and FIG.
FIG. 1 is a view taken along the line AA of FIG. 1, FIG. 3 is a view taken along the line BB of FIG. 1, FIG. 4 is a view taken along the line CC of FIG. 1, and FIG.
FIGS. 6 (B) and (C) are explanatory views showing the difference in the state of the light beam due to the difference in the diopter value of the eye to be examined in this embodiment. FIGS. 6 (A), (B), (C), (D) and (E) FIG. 7 (A) is an explanatory view showing the state of the light beam reflected from the light receiving system and the fundus of the subject's eye.
8 (A) and 9 (A) are explanatory diagrams showing the state of the reflected light flux at each point of the light source reaching the light receiving element, and FIGS. 7 (B), 8 (B) and 9 ( FIG. 10B is an explanatory view showing a change in the amount of light of each light beam when the light beam is blocked by the light blocking member.
FIG. 12, FIG. 12 is an explanatory diagram showing the light amount distribution state on the light receiving surface corresponding to the diopter value, and FIG. 13 is an explanatory diagram for obtaining the diopter value from the light amount distribution state, FIG. 14, FIG.
FIG. 16 is an explanatory view showing a change in the amount of light of each light beam when light is shielded by the light-shielding member when the spread width Δ on the light-shielding member is larger than 1/2 of the light source, and FIGS. 17 (A) and 17 (B).
(C) is a timing diagram for explaining motor control, FIG. 18 is a basic configuration diagram showing the second embodiment, and FIG.
FIG. 20 is a view as seen from an arrow D, and FIG. 20 is a view as seen from an arrow EE in FIG. 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, and 20 and 35 are slit plates. , 36y and 36z indicate dichroic mirrors.

Continued on the front page (72) Inventor Ikuo Kitao 75-1, Hasunuma-cho, Itabashi-ku, Tokyo Inside Topcon Corporation (72) Inventor Hiroaki Ogushi 75-1, Hasunuma-cho, Itabashi-ku, Tokyo Inside Topcon Corporation (56) Reference Literature Optics Vol. 18, No. 10, PP. 545-546 (58) Fields investigated (Int. Cl. ⁶ , DB name) A61B 3/103

Claims (2)

(57) [Claims] A projection system for projecting a measurement light source image on the fundus of the eye to be inspected; and a guide system for guiding a reflected light beam from the fundus onto a light receiving element disposed at a position substantially conjugate with the pupil of the eye to be inspected. A light-receiving system, wherein the light source emits a light beam from a plurality of meridians in an eye-refractive-power measuring apparatus that measures the eye refractive power of the subject's eye from the light amount distribution of the pupil image of the subject's eye formed on the light-receiving element. An edge-shaped light-shielding member configured to project and provide a mask plate that selectively transmits the plurality of light beams, and shields a part of the reflected light beam of each of the selected light beams in an optical path of the light receiving system; An eye refractive power measurement device, comprising: A projection system for projecting a measurement light source image on the fundus of the eye to be examined, and a light guide for guiding a reflected light beam from the fundus onto a light receiving element arranged at a position substantially conjugate with the pupil of the eye to be examined. A light-receiving system, the eye-refractive-power measuring device that measures the eye refractive power of the subject's eye from the light amount distribution of the pupil image of the subject's eye formed on the light-receiving element; An edge-shaped light-shielding member is provided in the optical path of the light receiving system so as to emit measurement light in different wavelength bands, and a reflected light beam passing through the edge-shaped light-shielding member is provided. A dichroic mirror for separating the light for each wavelength band.