JPH0355126B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an eye refractive power measurement device that objectively measures the refractive power of an eye. In particular, the present invention relates to an eye refractive power measuring device that projects a measurement target onto the fundus of an eye to be examined and determines the eye refractive power based on the state of formation of the target image on the fundus.

[Prior Art] As a conventional eye refractive power measuring device, there is one already proposed by the applicant in Japanese Patent Laid-Open No. 15839/1983. This eye refractive power measuring device includes a measurement target projection optical system for selectively projecting a pair of light beams from a measurement target onto the fundus of the eye to be examined, and means for rotating the pair of light beams around an optical axis. , a target is projected along the radial line, the imaging state of the target on the radial line is detected by a measurement target imaging optical system, and the detection signal is used to project the target on the radial line, and the detection signal is used to project the target on the radial line. This converts the refractive power of the subject's eye into the refractive power of the subject's eye.The structure is simplified and the measurement speed is fast.

[Disadvantages of conventional technology]

However, the above-mentioned eye refractive power measuring device is not designed to measure when the test subject blinks, and if the test subject blinks during measurement, it may be impossible to measure or may cause erroneous measurements. It was hot.

[Object of the present invention]

SUMMARY OF THE INVENTION An object of the present invention is to prevent erroneous measurements caused by blinking in a target projection type eye refractive power measurement apparatus as described above.

[Structure of the invention]

In order to achieve the above object, an eye refractive power measurement apparatus according to the present invention includes a plurality of targets, a measurement target projection optical system for projecting the light flux from the targets in at least four radial directions of the fundus of the eye to be examined, and a measurement target imaging optical system for forming a light beam from a measurement target image projected on a target image; a detection device for two-dimensionally detecting the position of the target image formed by the imaging optical system; measurement phase difference calculation means for calculating each of the measured phase differences in the at least four radial directions from the output; and approximate phase difference calculation for calculating an approximate phase difference curve according to the output of the detection device to obtain an approximate phase difference. means, deviation detection means for determining the difference between the measured phase difference and the approximate phase difference according to each radial direction, and comparison means for comparing the deviation detected by the deviation detection means with a predetermined maximum allowable deviation. , means for determining the eye refractive power by removing the corresponding measured phase difference when the output of the comparing means indicates a deviation exceeding the maximum allowable deviation.

The present invention is a measurement target projection method, which is applied to a type that detects the image formation position of the measurement target on the fundus in at least four radial directions. The measurement target may be moved along the optical axis, and the amount of change in the target image position before and after the movement is detected to determine the eye refractive power, or the measurement target may be moved along the optical axis along at least four radial lines. It can also be applied to a format in which the target image position is detected for each radial line by rotating the target image in the same direction.

Hereinafter, the measurement principle of the eye refractive power measuring device of the present invention will be explained with reference to the drawings. Referring to FIG. 1, a measurement target projection optical system consisting of a target T and an objective lens 2 is provided.
As shown by solid lines and dotted lines in the figure, the separated projection light beams are projected onto the fundus of the eye E to be examined along one radial line. For this purpose, for example, the target T is formed by a diaphragm aperture, two light sources I ₁ and I ₂ are provided behind the aperture and spaced apart in the radial direction with the optical axis in between, and the target T is illuminated through the lens 2. What is necessary is to project it onto the eye E to be examined. In the present invention, the projection of the target is performed along at least four radial lines, for example, by providing at least four sets of the above-mentioned light sources along at least four radial lines; Alternatively, the pair of light sources may be rotated around the optical axis and placed at positions along at least four radial lines. The reflected light from the fundus images O ₁ and O ₂ of the target T projected along each radial line is focused onto the light receiving surface of the detection device 4 by the lens 3 that constitutes the measurement target imaging optical system. imaged. The detection device 4 detects a target image in the fundus of the eye.
A signal related to the positions of O ₁ and O ₂ is output, and the output is input to the measured phase difference calculation means 5 and the approximate phase difference calculation means 6. The measurement phase difference calculation means 5 calculates a target image in each meridian from the output of the detection device 4.
As shown in Figure 2, the signals related to the distances O ₁ and O ₂ are measured using phase differences A, B, C, and D in the radial direction.
Output as . Approximate phase difference calculation means 6 approximately calculates and determines the phase difference in a range of 180° centered on the optical axis based on the output from detection device 4, as shown by E in FIG. Next, the outputs of the measured phase difference calculating means 5 and the approximate phase difference calculating means 6 are inputted to the deviation detecting means 7, and this deviation detecting means 7 calculates the measured phase differences A, B, C, D and the approximate phase difference in each meridian. E and a deviation signal corresponding to the difference is generated. This deviation signal is compared with the maximum permissible deviation signal in the comparing means 8, and when the deviation signal is large, the refractive power is determined based on the measured phase difference of the remaining radials excluding the measured phase difference of that radial. The refractive power determination means 9 performs this. For example, in FIG. 2, if the difference between the measured phase difference D and the approximate phase difference E is larger than the maximum allowable value, the eye refractive power is determined by the remaining measured phase differences A, B, and C.

In the present invention, all or part of the phase difference calculation means, approximate phase difference calculation means, deviation detection means, comparison means, and refractive power determination means can be implemented by adding an appropriate program to one microcomputer. .

〔Effect of the invention〕

As described above, the present invention compares the measured phase differences obtained for at least four meridians with an approximate phase difference based on those phase differences, and the resulting deviation allows those measured phase differences to be It determines whether the eye can be used to determine refractive power, so even if the subject's eye blinks during the eye examination, the blinking will have a large effect on the determined eye refractive power, resulting in erroneous measurements. This can be prevented.

[Explanation of Examples]

Configuration of Optical System FIG. 3 is a schematic diagram of an optical system showing an embodiment of the present invention. The optical system shown in FIG. 3 includes a target projection optical system 50 that projects a measurement target onto the fundus of the eye to be examined, and a target light receiving optical system 52 that projects a measurement target image of the fundus of the eye to be examined onto a measurement optical system 51.
and a fixation target system 53 that fixes the line of sight of the eye to be examined.
and an aiming optical system 54 that indicates the positional relationship between the eye to be examined and this device, and each optical system will be explained in detail below.

As shown in FIG. 3, the target projection optical system 50 includes a pair of infrared light sources 11a and 11b arranged around the optical axis.
A condenser lens 12 that condenses the light from b
a, 12b, collimator lens 13 that creates parallel light
and a measurement target 1 having a circular aperture stop 14
5, an imaging lens 16, and a projection imaging lens 17
It is composed of a half mirror 18 relating to infrared light, and a dichroic mirror 19 having a characteristic of reflecting infrared light in the long wavelength region and transmitting visible light and infrared light in the vicinity thereof. The above pair of infrared light sources 1
1a and 11b are turned on alternately at high speed, and both the sources 11a and 11b are configured to be rotatable together around the optical axis, and the measurement target 15 is configured to be movable in the optical axis direction. . Light from a pair of infrared light sources 11a and 11b is focused by condensing lenses 12a and 12b, respectively, and further collimated by a collimator lens 13 and obliquely incident on a circular aperture stop 14. The light that has passed through the circular aperture diaphragm 14 is imaged at a point _P1 by the imaging lens 16, passes through the projection imaging lens 17, is reflected by the half mirror 18 and the dichroic mirror 19, and is directed to the eye E. incident on . Here, the images of the infrared light sources 11a and 11b are formed on the pupil position of the eye E to be examined, and the image of the circular aperture stop 14 of the measurement target 15 is formed on the fundus _P2 of the eye to be examined. Then, the measurement target 15 and the fundus P ₂ of the eye E to be examined
When they are in a conjugate positional relationship, the image of the circular aperture stop 14 illuminated by the light from the infrared light source 11a and the image of the circular aperture stop 14 illuminated by the light from the infrared light source 11b are , fundus P ₂
imaged at the same location. On the other hand, when the measurement target 5 and the fundus _P2 of the eye E to be examined are not in a conjugate positional relationship, the image of the circular aperture diaphragm 14 irradiated with light from each infrared light source is the separated two parts of the fundus _P2 . An image is formed in each location. In the present invention, it is determined whether the images on the fundus _P2 of the circular aperture diaphragm 14 of the measurement target 15 fixed on the optical axis match or are separated by alternately lighting the infrared light sources 11a and 11b, and the images are separated. When the eye is being examined, the separation distance is measured, and the refractive power of the eye to be examined is determined from that measurement location and the position of the measurement target at that time.

As shown in FIG. 3, the target light receiving optical system 52 is formed on the reflected optical path of the dichroic mirror 19 and the transmitted optical path of the half mirror 18, and includes a light receiving objective lens 20, a mirror 21, and a light receiving objective lens 20. It is composed of a corneal reflected light blocking diaphragm 22 and a relay lens 23, which are arranged at a position conjugate with the cornea of the eye to be examined. As shown in FIG. 4, the corneal reflected light blocking diaphragm 22 is a diaphragm plate having a substantially circular hole in the center and protruding light blocking portions 22a and 22b formed at two symmetrical locations with respect to the optical axis passing position. be. Further, the corneal reflected light blocking diaphragm 22 is
When the infrared light sources 11a and 11b rotate around the optical axis, they are configured to rotate in conjunction with this rotational movement. Further, the corneal reflected light blocking diaphragm 22 is arranged at the front focal point of the relay lens 23, and the projection optical system using the relay lens 23 is configured as a telecentric optical system. The relay lens 23 is
It is configured to be movable in the optical axis direction in conjunction with the measurement target.

In the above configuration, the measurement target image of the fundus P ₂ of the eye to be examined is reflected by the dichroic mirror 19, passes through the half mirror 18, and is then transferred to the light receiving objective lens 20, the mirror 21, and the relay lens 23, which will be explained in detail later. It is projected into the measuring optical system 51. At this time, the harmful reflected light from the cornea of the eye to be examined is removed by the protruding light shielding portion 22a of the reflected light blocking diaphragm 22,
22b. Furthermore, since the corneal reflected light blocking diaphragm 22 and the relay lens 23 constitute a telecentric optical system, the measurement target image formed on the measurement optical system 51 is formed by a luminous flux consisting of principal rays parallel to the optical axis. The central position of the circular hole image, which is the measurement target image, does not shift even before and after the imaging position.

As shown in FIG. 5, the measuring optical system 51 includes an X-direction detection system 86 consisting of a half mirror 55, a mirror 56, a relay lens 57, a mirror 58, a chopper 59, a condenser lens 60, and a light receiving element 61; a mirror 62 provided on the reflected optical path;
Y-direction detection system 87 consisting of a relay lens 63, a chopper 59, a condensing lens 64, and a light receiving element 65
and a reference signal generation system 88 consisting of a light emitting element 66, condensing lenses 67 and 68, and a light receiving element 69. The chopper 59 has a group of continuous slits in the circumferential direction and rotates around the optical axis.

In the above configuration, the measurement target image of the fundus P ₂ of the eye to be examined is projected near the upper part 59 a of the chopper 59 by the target light receiving optical system 52 and the X-direction detection system 86 . At the same time, a measurement target image of the fundus P ₂ of the eye to be examined is projected near the side portion 59b of the chopper 59 by the target light receiving optical system 52 and the Y-direction detection system 87.
Here, if the measurement target 15 and the fundus _P2 of the eye to be examined are not in a conjugate relationship, circular aperture images 30a, 30b and 30a', formed by the light from the infrared light sources 11a and 11b, as shown in FIG. 30
b' is projected onto the slit group separated by Δx in the X direction and Δy in the Y direction. When the infrared light source 11a is turned on and the circular aperture image 30a produced by the light is scanned by the chopper 59, the signal from the light receiving element 61 and the signal from the light receiving element 61 when the infrared light source 11b is turned on and the circular aperture image 30b produced by the light are scanned by the chopper 59. Therefore, Δx is calculated from the phase difference with the signal from the light receiving element 61 during scanning. Similarly, circular aperture image 3
From the phase difference of the signal from the light receiving element 65 when the chopper 59 scans 0a' and 30b',
Calculate y. Here, the measurement target 15
and the fundus _P2 of the eye to be examined, the degree of astigmatism of the eye E to be examined, and the circular aperture image 30 on the stopper 59.
The relationship between a and 30b will be explained. Light sources 11a, 11
b are arranged side by side at positions rotated by θ from the vertical direction. That is, it is assumed that the measurement radial direction is a direction rotated by θ from the vertical direction.

(1) When the measurement target 15 and the fundus _P2 of the eye to be examined are in a conjugate relationship, and the eye E to be examined does not have astigmatism, as shown in FIG.
On the top, circular aperture images 30a and 30b are projected to overlap at the optical axis passing position. That is, △x
=Δy=0.

(2) When the measurement target 15 and the fundus P ₂ of the eye to be examined are not in a conjugate relationship and the eye E to be examined does not include astigmatism or includes astigmatism, the diameter measured by the main axis of the eye E and the light sources 11a and 11b. When the line directions match, as shown in FIG. 7B, circular aperture images 30a and 3 are formed on the chopper 59.
0b is projected separately in the measurement radial direction.

(3) When the measurement target 15 and the fundus P ₂ of the eye to be examined are not in a conjugate relationship, the eye E to be examined includes astigmatism, and the main meridian of the eye E to be examined and the direction of the measurement meridian consisting of the light sources 11a and 11b are different. In Figure 7C
As shown in FIG. 2, circular aperture images 30a and 30b are separately projected on the chopper 59 in the measurement radial direction and in a direction perpendicular thereto.

In this example, as shown in Fig. 7, the separation amounts △x and △y in the horizontal and vertical directions are detected, and the detection results are converted into separation amounts in the measurement radial direction. It detects eye refractive power.

By performing the above conversion, the light sources 11a, 1
By simply rotating 1b, the eye refractive power in each measurement radial direction can be determined.

As shown in FIG. 3, the fixation target system 53 includes a visible light source 31, a condenser lens 32, a fixation target 33 movable in the optical axis direction, a mirror 34, a projection lens 35, and a red light source that reflects visible light. It is composed of a dichroic mirror 36 that transmits external light.

In the above configuration, the light from the visible light source 31 is directed to the fixation target 33 via the condensing lens 32.
irradiate. The light from the fixation target 33 passes through a mirror 34, a projection lens 35, a dichroic mirror 36, and the dichroic mirror 9, and is projected onto the eye E to be examined. The subject is
The collimation direction is fixed by gazing at the fixation target 33. Furthermore, the eye to be examined is required to always be in a far viewing state, and the fixation target 33 is movable in the optical axis direction and adjusted to a position where the eye to be examined is in a far viewing state.

The aiming optical system 54 includes a projection lens 36a, a half mirror 37, and an image pickup tube 38, which are provided on the transmission optical path of the half mirror 19 and the dichroic mirror 36, and a light source 40 and a condenser on the reflection optical axis of the half mirror 37. Optical lens 41, collimating plate 42,
It has a mirror 44 and a projection lens 45. The image pickup tube 38 is connected to a monitor television 39. As shown in FIG. 8, the collimating plate 42 has a collimating scale 43 having a circle in the center and radiation around the circle.

In the aiming optical system configured as above,
On the image pickup tube 38, an image of the anterior segment of the eye E to be examined by the projection lens 36a and an image of the collimation scale 43 by the projection lens 45 are projected in a superimposed manner. The examiner looks at the monitor television 39 and sees that the center of the pupil image of the eye to be examined and the image of the collimation scale 43 match, and the optical axis of the eye to be examined and the optical axes of the target projection optical system 50 and the target light receiving optical system 52 are aligned. Move the device vertically, horizontally, and horizontally relative to the eye to be examined so that the

Next, the configuration of the electric circuit of this device will be explained based on the block diagram of FIG. The control circuit 101 includes a power switch 102, a measurement switch 103, a chopper drive circuit 104, a light source drive circuit 105, a measurement target drive circuit 106, a fixation target drive circuit 107, and a measurement target light source rotation drive circuit 1.
08, it is connected to the measurement detection section 109 and the arithmetic processing section 110, and controls these according to a predetermined program.

The chopper drive circuit 104 is connected to and drives a motor 112 that rotates the chopper 19. The light source driving circuit 105 is connected to the reference signal light emitting element 26 and the measurement target light sources 1a and 1b, and lights them. Measurement target drive circuit 1
06 is connected to and drives a motor 114 that moves the measurement target 5 on the optical axis. A fixation target drive circuit 107 is connected to and drives a motor 116 that moves the fixation target on the optical axis. The measurement target light source rotation drive circuit 108 is connected to a motor 118 that rotates the measurement target 5 around the optical axis. The light receiving element 29 receives the light emitted by the reference signal light emitting element 26 and passing through the chopper 19.
A reference signal is input to the amplifier circuit 120. The amplifier circuit 120 includes a waveform shaping circuit 122 and a waveform shaping circuit 1.
22 is connected to a first phase difference detection circuit 124 and a second phase difference detection circuit 126. A light receiving element 21 receives the light emitted by the measurement target light sources 1a and 1b and passes through the upper part 19a of the chopper 19.
is connected to an amplifier circuit 127, and the amplifier circuit 127 is further connected to an AGC circuit 128;
is connected to the waveform shaping circuit 130, and the waveform shaping circuit 130 is connected to the first phase difference detection circuit 124. Similarly, the light receiving element 25 that receives the light emitted by the measurement target light sources 1a and 1b and passed through the side part 19b of the chopper 19 is connected to an amplifier circuit 132, and the amplifier circuit 132 is further connected to the AGC circuit 134.
The AGC circuit 134 connects the waveform shaping circuit 136 to
The waveform shaping circuit 136 is the second phase difference detection circuit 126
is connected to. The first phase difference detection circuit 124 detects the phase difference between the reference rectangular wave output from the waveform shaping circuit 122 and the rectangular wave output from the waveform shaping circuit 130, and outputs it as a phase difference signal Xa. Similarly,
The second phase difference detection circuit 126 is a waveform shaping circuit 122
The phase difference between the reference rectangular wave output by the waveform shaping circuit 136 and the rectangular wave output by the waveform shaping circuit 136 is detected, and a phase difference signal is generated.
Output as Ya. First phase difference detection circuit 124
and the second phase difference detection circuit 126 are connected to a measurement phase difference calculation circuit 138, and the measurement phase difference calculation circuit 138 is further connected to the calculation processing section 110.

The measurement phase difference calculation circuit 138 operates on the light emitting element 1
The measured phase difference Δx between the phase difference signals Xa and Xb output by the first phase difference detection circuit 124 when the light emitting elements 1a and 11b are turned on, and the second phase difference detection circuit when the light emitting elements 11a and 11b are also turned on. The measured phase difference ΔY between the phase difference signals Ya and Yb outputted by 126 is calculated.

This measured phase difference △X, △Y is shown in FIG.
This corresponds to the separation amounts Δx and Δy of the circular aperture images 30a and 30b in the X and Y directions. Arithmetic processing unit 11
0 is the separation amount in the measurement meridian direction from the rotational position angle θi of the measurement target light source, which is a signal from the target light source drive circuit, and the measurement phase differences △Xi, △Yi using the following equation (5). Corresponding measurement phase difference△
pθi is calculated according to the following equation (5).

△pθi = △Xicosθi + △Ysinθi (1) This measured phase difference △pθi is converted to the separation amount △ of the circular hole aperture image in the measurement meridian direction, and the following principle is used to calculate the refractive power from this separation amount △. The refractive power Dθ of the eye to be examined in the measurement meridian direction θ is calculated according to the formula.

△=mfx (Dθ−DT) (2) Where, m: Imaging magnification of the aperture for the eye to be examined f: Focal length of the relay lens x: Distance between two light beams in the pupil of the eye to be examined DT: Diopter conversion value in at least four meridian directions.
Calculate D〓(D〓 ₁ , D〓 ₂ , D〓 ₃ , D〓 ₄ ). This D〓 ₁
，
D〓 ₂ , D〓 ₃ , D〓 ₄ are spherical power A, astigmatic power B,
When the astigmatic axis is α, it is expressed by the following equation.

D〓 ₁ =A+Bcos2(θ ₁ −α) D〓 ₂ =A+Bcos2(θ ₂ −α) D〓 ₃ =A+Bcos2(θ ₃ −α) D〓 ₄ =A+Bcos2(θ ₄ −α) (3) From this result , spherical power A, astigmatic power B, and astigmatic axis α are determined and output to the display 142.

In the above method, the spherical power A, the astigmatic power B, and the astigmatic axis α are calculated only from the measured phase difference △pθi corresponding to the amount of separation in the measured meridian direction, but the astigmatic power B and the astigmatic axis α are calculated as follows. The calculation method is valid. That is, from the measured phase difference △Xi, △Yi
In addition to calculating the phase difference △pθi corresponding to the separation amount in the measurement meridian direction according to equation (5), the measurement phase difference △PII corresponding to the separation amount in the direction perpendicular to the measurement meridian direction is calculated according to the following equation. .

ΔP⊥i=−ΔXisinθi+ΔYicosθi (4) The resulting calculated ΔP⊥i is expressed by the following equation (8) similarly to equation (3).

△P⊥ ₁ = Bcos2 (θ _{1 -} α) △P⊥ ₂ = Bcos2 (θ _{2 -} α) △P⊥ ₃ = Bcos2 (θ ₃ - α) △P⊥ ₄ = Bcos2 (θ _{4 -} α) (5 ) That is, ΔP⊥i obtained by this calculation is not affected by the spherical power A. This means that it is not affected by the accommodation of the eye to be examined, that is, by fluctuations in the spherical power A during the measurement period. If the astigmatism degree B and astigmatism axis α are determined from equation (5), it is possible to obtain highly accurate detection results for the astigmatism power B and astigmatism axis α without being influenced by the measurement of the subject during the measurement period. be. Note that in this case as well, equations (1) and (3) are used to calculate the spherical power A.

The operation of the electric circuit configured as described above is as follows. The power switch 102 is turned on, and the optical axis of the subject is made to coincide with the optical axes of the target projection optical system 50 and the target light receiving optical system 52 using the aiming optical system 54. Further, the control circuit 101 rotates the chopper 19, turns on the reference light emitting element 26, and turns on the light sources 1a and 1b of the target projection optical system alternately. These rotations and lighting continue until the measurement is completed. Furthermore, under the control of the control circuit 101, the measurement target drive circuit 106 drives the motor 114 to move the measurement target 15 to a predetermined position, for example, +6 diopters, and the fixation target drive circuit 107 drives the motor 116 to fix the measurement target 15. The visual target 33 is moved to a predetermined position, for example, +20 diopters, and the measurement target light source rotation drive circuit 108 drives the motor 118 to rotate the light sources 11a and 11b of the measurement target 15 vertically (rotation angle θ=0°). ) rotationally move to the position. This completes the preparation for preliminary measurement.

Next, under the control of the control circuit 101, the light receiving element 6
1, 65, and 69 receive the respective signal lights,
According to the circuit configuration described above, the arithmetic processing unit 110 calculates a phase difference ΔPθo corresponding to the amount of separation of the circular hole aperture images in the meridian plane (θ=0°). This ΔPθo is converted into a separation amount of the hole aperture image, and the refractive power of the eye to be examined in the meridian plane (θ=0°) is calculated based on the position of the measurement target 15 at that time. This calculation result is converted into the amount of movement of the measurement target 15 and input to the control circuit 101. Based on this signal, the control circuit 101 controls the measurement target drive circuit 106, and the motor 114 moves the measurement target 15 to a position corresponding to the refractive power of the eye to be examined in the measurement meridian direction at θ=0°, that is, when the measurement target 15 and the fundus of the eye to be examined are almost conjugate. The measurement target 15 is moved to a related position farther from the position of the measurement target 15. In this state, the measurement target 15 and fixation target 33 are fixed, and the following main measurement begins. The position of the measurement target 15, which has been moved and fixed as a result of the preliminary measurement, is not changed during the main measurement.

The preliminary measurement described above is effective for further improving the accuracy of the following main measurement by setting the position of the measurement target 15 at a substantially conjugate position of the fundus of the eye to be examined.

In this measurement, the detection described in the preliminary measurement is performed in the same way. In this measurement, the measurement target light source rotation drive circuit 108 drives the motor 118 in response to a signal from the control circuit 101, and sequentially rotates the measurement target light sources 11a and 11b around the optical axis, thereby changing the measurement phase difference in the measurement radial direction. Dθ is calculated by the measurement phase difference calculation circuit 138. This measurement is performed in at least four radial directions, and the phase differences at that time are indicated by P〓 ₁ , P〓 ₂ , P〓 ₃ , and P〓 ₄ . The calculation processing flowchart of the calculation processing unit 110 at the time of this measurement is the 10th
As shown in the figure.

The main measurement is started, and the measured phase difference of each radial line is inputted from the measured phase difference calculation circuit 138 as described above, and this becomes the first step. In the second step, the coefficient B of the above-mentioned equation (5) is determined from each measured phase difference by the method of least squares, and the curve determined by this is an approximate phase difference curve. Applies to. The third step is to calculate an approximate phase difference in the radial direction with the measured phase difference based on the obtained approximate phase difference curve in order to compare the measured phase difference with the approximate phase difference.Approximate phase difference calculation means Applies to. The fourth step is to find the deviation between the measured phase difference and the approximate phase difference for each radius line by subtraction. The fifth step is to determine whether or not the obtained deviation is larger than a predetermined maximum allowable deviation, and to extract it.

Measured phase differences that deviate from the normal value caused by blinking of the subject's eye will be extracted in this step. In the sixth step, the measured phase difference of the radius line that caused the deviation extracted in the fifth step is deleted. In the seventh step, the remaining measured phase difference after deletion, that is, the number of detected values when no blinking occurs, is counted, and it is determined whether it is 3 or more. If the number is 3 or more, the process proceeds to the eighth step, but if it is less than 3, the refractive power cannot be determined by the least squares method, so the process returns to the first step and is remeasured. In the eighth step, using the remaining measured phase difference, an approximate phase difference curve is again calculated by the least squares method using equation (3) or equations (3) and (5).
In the ninth step, the refractive power (spherical power A, astigmatic power B, astigmatic axis α) is calculated and determined from the approximate phase difference curve. The tenth step is to appropriately display the determined refractive power.

In this embodiment, preliminary measurements were carried out in one meridian direction, but it goes without saying that measurements may be carried out in two or more meridian directions. Furthermore, after performing a preliminary measurement in one meridian direction, it is also possible to perform preliminary measurements again in two or more meridian directions to further improve the accuracy of the main measurement. Further, in this example, preliminary measurements are performed before the main measurements, but even if the main measurements are directly performed without performing the preliminary measurements, the present invention can be effectively implemented and the effects of the present invention can be achieved. can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram for explaining the operating principle of the present invention, FIG. 2 is a diagram for explaining signal processing in the present invention, FIG. 3 is an optical diagram of an embodiment of the present invention, and FIG. 3 is a front view of the corneal reflected light blocking diaphragm of the embodiment, FIG. 5 is an optical diagram of the measurement optical system, FIG. 6 is an explanatory diagram of the measurement principle of the measurement optical system shown in FIG. 5, and FIG.
The figure is also an explanatory diagram of the measurement principle of the measurement optical system, No. 8
The figure is a front view of the fixation target of this embodiment, and FIG. 9 is a block diagram of the electric circuit used in this embodiment.
FIG. 10 is a flowchart showing the operation of the arithmetic processing circuit. 11a, 11b... Infrared light source, 14... Circular aperture stop, 17... Projection imaging lens, 18...
Half mirror related to infrared light, 19... Dichroic mirror, 61... Light receiving element, 69... Light receiving element, 50... Target projection optical system, 51...
Measurement optical system, 52...Target light receiving optical system, 5
3... Fixation target system, 54... Aiming optical system, 101
... Control circuit, 102 ... Power switch, 103
...Measurement switch, 104...Chopper drive circuit, 105...Light source drive circuit, 106...Measurement target drive circuit, 107...Fixation target drive circuit, 108...Measurement target light source rotation drive circuit, 109...Measurement Detection unit, 110...Arithmetic processing unit, 142...Display device.

Claims (1)

[Claims] 1. A measurement target projection optical system for projecting the light flux from the measurement target onto at least four meridians of the fundus of the eye to be examined; and a measurement target imaging optical system for forming the light flux from the measurement target image projected onto the fundus. , a detection device that two-dimensionally detects the position of the target image formed by the imaging optical system; and a measurement phase difference calculation that calculates measurement phase differences in the at least four radial directions from the output of the detection device. means, approximate phase difference calculation means for calculating an approximate phase difference according to the output of the detection device to obtain an approximate phase difference, and deviation detection means for calculating a difference between a measured phase difference and an approximate phase difference in each radial direction. and comparing means for comparing the deviation detected by the deviation detecting means with a predetermined maximum allowable deviation, and when the output of the comparing means indicates a deviation exceeding the maximum allowable deviation, a corresponding measured phase difference. 1. An eye refractive power measuring device comprising means for determining the refractive power of an eye to be examined using the remaining measured phase difference.