JP2006187482A - Eye refracting power measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an eye refracting power measuring device by which a precise measuring result can be obtained. <P>SOLUTION: The eye refracting power measuring device objectively measuring the refracting power of an eye to be measured has a projecting optical system having a measuring light source emitting the light beam for measuring the eye refracting power and projecting a measuring light beam to the fundus of the eye to be measured, a light receiving optical system allowing a 2D imaging element to receive the reflected light from the fundus of the eye by the measuring light beam as a 2D pattern image, a calculating means calculating the eye refracting power of the eye to be measured from the 2D pattern image received in the 2D imaging element by the light receiving optical system, the measuring light source is a superluminescent diode or a laser diode having a central wavelength of 850 to 940 nm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an eye refractive power measuring apparatus that objectively measures the eye refractive power of a subject's eye.

A light beam for measuring eye refractive power is projected onto the fundus of the subject's eye, and reflected light from the fundus is received by the two-dimensional light receiving element, and a pattern image (ring pattern image or a plurality of dot pattern images) detected by the two-dimensional light receiving element is received. Etc.) is known (for example, see Patent Document 1). Conventionally, an LED (light emitting diode) has been used as a measurement light source of an apparatus having such a configuration.
JP-A-1-293841

  By the way, since the measurement light source and the two-dimensional light receiving element are placed at a position conjugate with the fundus (for example, when measuring the normal eye), when an LED is used as the measurement light source, the size of the spot image projected onto the fundus is large because the light source size is large. And the brightness of the measurement image is lowered. In addition, since the diameter of the measurement light beam becomes large, it is considered that scattering at each part (a crystalline lens, a vitreous body, etc.) in the eye due to the measurement light increases. Therefore, there is a problem that a lot of noise light is included in the measurement image and the measurement accuracy is deteriorated.

  In view of the above problems, it is an object of the present invention to provide an eye refractive power measuring apparatus capable of obtaining a highly accurate measurement result.

  The present invention is characterized by having the following configuration in order to solve the above-described problems.

(1) In an eye refractive power measurement apparatus that objectively measures the eye refractive power of the eye to be examined, a projection optical system that includes a measurement light source that emits a light flux for measuring eye refractive power and projects the measurement light flux on the fundus of the eye to be examined And a light receiving optical system that causes the two-dimensional image sensor to receive a reflected light beam from the fundus as a result of the measurement light beam, and the two-dimensional image received by the two-dimensional image sensor by the light receiving optical system. Computing means for computing the eye refractive power of the eye to be examined, and the measurement light source is a super luminescent diode or a laser diode, the center wavelength of which is 850 to 940 nm.
(2) The eye refractive power measuring device according to (1) obtains the intensity of the received light signal necessary for obtaining the eye refractive power from the two-dimensional pattern image received by the two-dimensional image sensor, and the two-dimensional Based on the wavelength region of the measurement light emitted by the measurement light source and the wavelength sensitivity characteristic of the two-dimensional image sensor, in order to suppress the received light signal that is a noise component included in the two-dimensional pattern image received by the image sensor. The imaging gain of the two-dimensional imaging device is set.
(3) In the eye refractive power measurement device according to (2), the two-dimensional pattern image received by the two-dimensional imaging device is a ring pattern image, and the setting of the imaging gain of the two-dimensional imaging device is the two-dimensional pattern image It is characterized by being performed so as to suppress noise components generated in the inner region.
(4) In the eye refractive power measurement device according to (2), the setting of the imaging gain is such that the waveform of each luminance signal when detecting the position of the two-dimensional pattern image received by the two-dimensional imaging device is the waveform of the luminance signal. It is characterized by being set to be symmetrical with respect to the peak.
(5) The eye refractive power measurement device according to (1) acquires a plurality of two-dimensional pattern images picked up by the two-dimensional light receiving element, and adds the processed images obtained by adding the plurality of image data. Arithmetic processing means for obtaining the eye refractive power of the eye to be examined based on the data.
(6) In the eye refractive power measurement device according to (5), before adding the image data to each other by the arithmetic processing unit, a measurement signal of a predetermined noise component is previously removed by subtraction processing for each image data. Subtracting means is provided.

  According to the present invention, an accurate measurement result can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an optical system and a control system of the eye refractive power measurement apparatus of the present embodiment. The measurement optical system 10 includes a projection optical system 10a that projects a spot-like light beam from the center of the pupil of the eye to be examined to the fundus, and a light receiving optical system 10b that extracts the reflected light from the periphery of the pupil in a ring shape. The projection optical system 10 a includes a measurement light source 11, a relay lens 12, a hall mirror 13, a prism 15 that is driven to rotate about the optical axis L 1 by a driving unit 23, and a measurement objective lens 14. And arranged in this order toward the eye to be examined.

  The measurement light source 11 used in the present embodiment uses a super luminescent diode (SLD) that emits light in the infrared region. An SLD having a center wavelength of 850 nm or more and 940 nm or less can be preferably used. More preferably, it is not less than 870 nm and not more than 900 nm. When the center wavelength is less than 850, visual observation can be performed during the measurement, so that it is difficult to apply the cloud to the eye to be examined during the measurement, which affects the measurement accuracy. In addition, when the center wavelength exceeds 940 nm, absorption by the crystalline lens or vitreous body increases, and the amount of measurement light reaching the fundus or reflected light from the fundus is reduced, and the amount of light necessary for measurement is secured. It becomes difficult. In the present embodiment, the SLD is used as the measurement light source 11 having strong directivity. However, the present invention is not limited to this, and for example, a laser diode (LD) or the like can be considered.

  The light source 11 has a conjugate relationship with the fundus of the eye to be examined, and the hole portion of the Hall mirror 13 has a conjugate relationship with the pupil. The prism 15 arranged in the common optical path of the projection optical system 10a and the light receiving optical system 10b is arranged at a position deviated from the position conjugate with the fundus of the eye E, and is a spec generated by using a light source having high coherence. In order to suppress noise, the passing light beam is rotated eccentrically with respect to the optical axis L1. The reflected light beam from the fundus passes through the same prism 15 as that of the projection optical system 10a, so that it is as if the projected light beam / reflected light beam (received light beam) on the pupil is not decentered in the subsequent optical system. . Instead of the prism 15, a plane parallel plate may be arranged obliquely on the optical axis L1. A beam splitter 29 is disposed between the measurement objective lens 14 and the eye to be examined.

  The light receiving optical system 10 b shares the objective lens 14, the prism 15, and the hall mirror 13 of the projection optical system 10 a, and is arranged in the reflection direction of the relay lens 16, the mirror 17, and the mirror 17 disposed on the optical path in the reflection direction of the hall mirror 13. A light receiving diaphragm 18 disposed in the optical path, a collimator lens 19, a ring lens 20 disposed at a position conjugate with the eye pupil to be examined, and a two-dimensional image sensor 22 such as an area CCD are provided. The light receiving diaphragm 18 and the two-dimensional image sensor 22 are in a conjugate relationship with the fundus of the eye to be examined. The two-dimensional image sensor 22 is connected to the control unit 70 via the frame memory 71.

  As shown in FIGS. 2A and 2B, the ring lens 20 includes a lens portion 20a in which a cylindrical lens is formed in a ring shape on a flat plate, and a light shielding material in which a coating for light shielding is applied in addition to the lens portion 20a. It is comprised from the part 20b. As a result, the ring pattern image is collected on the two-dimensional image sensor 22 arranged at the focal position. In the present embodiment, the ring lens 20 is configured to receive the ring pattern image by the ring lens 20. However, as the light receiving optical system, a Hartmann Shack plate having a configuration in which microlenses are arranged in a grid pattern. Alternatively, an optical system may be used in which the two-dimensional image sensor 22 receives a two-dimensional pattern image using a six-hole aperture and a deflecting prism.

  On the optical axis L2 that is made coaxial with the optical axis L1 by the beam splitter 29, an objective lens 36, a half mirror 35, a dichroic mirror 34, a light projection lens 33, a fixation target 32, and a visible light source 31 are sequentially arranged. The fixation target optical system 30 is configured by the light source 31 to the observation system objective lens 36. The fixation target 32 performs clouding of the eye to be examined by moving in the direction of the optical axis L2. The light source 31 illuminates the fixation target 32, and the light flux from the fixation target 32 passes through the projection lens 33, the dichroic mirror 34, the half mirror 35, and the objective lens 36, and then is reflected by the beam splitter 29 toward the eye to be examined. . An alignment optical system 40 is provided on the reflection side of the dichroic mirror 34, and includes an alignment light source 41 and a light projection lens 42 that emit infrared light. The light beam from the light source 41 projects an alignment index on the eye cornea through the projection lens 42 and the dichroic mirror 34 to the beam splitter 29.

  On the reflection side of the half mirror 35, an imaging lens 51 and an area sensor 52 for observing the anterior eye part are arranged to constitute an observation optical system 50. The reflected light from the anterior segment including the alignment index is reflected by the beam splitter 29 and then received by the area sensor 52 via the lens 36, the half mirror 35, and the photographing lens 51. The output of the area sensor 52 is connected to the monitor 7 via the image processing unit 77, and an observation image is displayed.

  The operation of the apparatus having the above configuration will be described. At the time of measurement, the examiner adjusts the apparatus with respect to the eye E shown in FIG. 1 by operating a joystick (not shown) based on the anterior segment image and the alignment index displayed on the monitor 7. Then, the fixation target 32 is fixed with respect to the eye E, and when the alignment is in an appropriate state, the measurement start switch 73 is pressed to start measurement.

The control unit 70 turns on the light source 11 by the measurement start signal from the switch 73 and rotates the prism 15 at a high speed by the driving unit 23. Then, preliminary measurement for applying cloudlessness to the eye to be examined is performed, and after the fixation target 32 is once placed at a position conjugate with the fundus based on the refractive power obtained there, the control unit 70 performs an appropriate measurement. The fixation target 32 is moved so that the fog is applied by the amount of diopter. Thereby, this measurement is performed in the state which applied the cloud fog with respect to the eye to be examined.
If the measurement light of the measurement light source 11 is slightly visible when cloudless, the color scheme of the fixation target 32 can be determined so that the color of the measurement light is assimilated to the fixation target. For example, the fixation target 32 may be a red-based fixation target.

The infrared light emitted from the light source 11 forms a spot-like point light source image on the fundus of the eye E through the relay lens 12, the hall mirror 13, the prism 15, the objective lens 14, and the beam splitter 29. At this time, the pupil projection image (projected light beam on the pupil) of the hall portion of the hall mirror 13 is eccentrically rotated at high speed by the prism 15 rotating around the optical axis.
The point light source image projected onto the fundus is reflected and scattered, exits the eye E, passes through the beam splitter 29, is collected by the objective lens 14, and is rotated at a high speed by the prism 15, the hall mirror 13, and the relay lens. 16, the light is condensed again at the position of the light receiving aperture 18 via the mirror 17, and forms an image in a ring shape on the two-dimensional image sensor 22 by the collimator lens 19 and the ring lens 20. The output signal from the two-dimensional image sensor 22 is stored as image data by the frame memory 71. When the eye E is a normal eye, the fundus reflection light is incident on the ring lens 20 as a parallel light beam, and thus a ring image having the same size as the ring lens 20 is formed on the two-dimensional image sensor 22. On the other hand, when the eye E has a refractive error of the spherical refraction component, the ring diameter of the ring image formed on the two-dimensional image sensor 22 is proportional to the amount of deviation of the spherical refraction error (for a myopic eye). Smaller and larger for hyperopic eyes). When there is an astigmatism refraction error, the ring image formed on the two-dimensional image sensor 22 has an elliptical shape according to the astigmatism refraction error. Therefore, the control unit 70 can obtain the refraction error in each meridian direction by detecting the position of the ring image in each meridian direction based on the image data stored in the frame memory 71, and can perform a predetermined process on this. , The refractive values of S (spherical power), C (astigmatic power), and A (astigmatic axis angle) can be obtained. The ring image position can be detected from the center position of the edge of the ring image, the barycentric position of the luminance level, the peak position of the light amount level, or the like. In addition, the light source 11, the light receiving diaphragm 18, the lens 19, the ring lens 20, and the two-dimensional image sensor 22 are configured to be integrally movable in the optical axis direction, and the light source 11 and the two-dimensional image sensor 22 are retinal conjugate. The refraction value may be obtained from the amount of movement up to and the shape of the ring image.

  In addition, when a light source having a high brightness and high coherence like SLD is used without the prism 15, speckle noise is generated in the ring image received by the two-dimensional image sensor 22 due to scattering in the eye. However, in this embodiment, the spot light beam (point light source image) projected on the fundus of the subject's eye is rotated eccentrically at high speed (high-speed rotation of the prism 15). Therefore, speckle noise in the case of using a light source (SLD) with high coherence is neutralized during the imaging time of the two-dimensional imaging device 22, and the influence can be removed.

  Note that the SLD has a smaller light source size and higher directivity than an LED (light emitting diode), and therefore can realize a measurement light beam having a narrow light beam diameter. As a result, a small spot image is projected on the fundus of the eye to be examined, and scattering at each site in the eye is reduced. Therefore, the two-dimensional imaging element 22 that receives the reflected light has less noise and has a sharp thin ring width. The ring pattern image can be captured. The spot image projected onto the fundus has an SLD of about 10 μm in diameter and an LED of about 50 μm in diameter. When an LED is used as a measurement light source, the ring width is large and there are many around the ring image. The flare component is imaged. That is, compared with a device using an LED as a measurement light source, the device of the present embodiment can obtain a refractive power based on a sharp ring pattern image with less noise, and obtain an accurate measurement result with little measurement error. It becomes possible.

  When a light source having a small light source size such as SLD or LD and having high directivity is used as the measurement light source, the measurement light beam can be easily visually observed when the center wavelength is about 830 nm. For this reason, it is preferable to use a light beam on the longer wavelength side, but the wavelength sensitivity of the image sensor decreases as the wavelength shifts to the longer wavelength side. Therefore, in order to further increase the measurement accuracy, it is necessary to set the imaging gain of the two-dimensional image sensor 22 in consideration of the wavelength region of the measurement light source 11 and the wavelength sensitivity characteristics of the two-dimensional image sensor 22.

The setting of the imaging gain of the two-dimensional image sensor in the apparatus according to the present embodiment will be described below.
For example, when an imaging device having the characteristics shown in FIG. 3 is used, the sensitivity of 875 nm light is reduced by about 40% compared to 830 nm light. That is, when an 875 nm SLD is used as the measurement light source 11, the luminance signal detected by the two-dimensional image sensor 22 is reduced by 40%. As a result, the ring image becomes dark overall. For this reason, a method of increasing the imaging gain of the two-dimensional imaging device 22 by the amount of sensitivity reduction is conceivable (for example, if the light amount level is reduced by 40%, the gain may be increased by about 1.7 times). ). However, when the eye is measured by simply increasing the imaging gain by the shortage of the light amount, the necessary light amount can be obtained, but noise light (scattered light or reflected light from the crystalline lens or vitreous body in the eye) is detected. Was found to increase. More specifically, the noise component in the inner region tends to increase from the outer region of the ring pattern image, and the refraction value obtained shifts from the original value to the minus side (myopia direction) due to the influence of this noise component. Resulting in.

  FIG. 4A is a diagram (a position in the X direction and a luminance level in the Y direction) showing a part of the waveform of the luminance signal in the predetermined meridian direction in the ring image when many noise components are included. In this case, the waveform is asymmetrical, and the inclination of the waveform is gentle (the edge is steep). If the ring image position is detected from such a waveform, measurement errors are likely to occur due to the influence of noise. For example, when the obtained waveform is cut at the threshold value S and an intermediate point of the waveform at this cutting position is detected as the image position, if the waveform is left-right asymmetric, the threshold S is set according to the set position (S1, S2). The detection positions (A1, A2) of the image position will fluctuate. Further, the fact that the inclination of the waveform is reduced and the width of the luminance level at the threshold S is increased is also a factor for increasing the measurement error.

  Therefore, in order to suppress the received light signal that becomes a noise component included in the two-dimensional pattern image received by the two-dimensional image sensor while obtaining the required intensity of the received light signal, the wavelength region of the measurement light source and 2 Based on the wavelength sensitivity characteristic of the two-dimensional image sensor 22, the gain of the two-dimensional image sensor 22 is adjusted (set). For example, the gain of the CCD camera is adjusted based on whether the waveform of the luminance signal when detecting the image position of the ring pattern image is substantially symmetric as shown in FIG. In this case, as the gain of the two-dimensional image sensor 22 is changed, a range in which the waveform of the luminance signal is symmetric with respect to the peak of the waveform may be set. As a method for obtaining the left-right symmetry of the waveform, for example, two different threshold values S1 and S2 are set for the waveform, and the position A1 with the intermediate point of the waveform obtained by the set threshold values S1 and S2 as the image position and A method is conceivable in which the deviation amount Δd of A2 is determined by whether or not it falls within a predetermined allowable value. In this way, by adjusting the gain so that a waveform that satisfies a predetermined standard can be obtained, the measurement accuracy is further improved by detecting the image position from the waveform of the luminance signal that is not easily affected by noise light. be able to. When the two-dimensional pattern image received by the two-dimensional image sensor 22 is a ring pattern image as in the present embodiment, the setting of the imaging gain of the two-dimensional image sensor is an inner area of the two-dimensional pattern image. What is necessary is just to adjust an imaging gain so that the noise component which arises in this may be suppressed.

  In addition, since the slope of the waveform becomes gentle when the noise component is included in the waveform signal, the slope of the waveform of the luminance signal may be considered in the gain adjustment. As a method of obtaining the slope of the waveform, for example, a method of selecting based on the differential coefficient f ′ of the waveform near the intermediate position between the peak and the minimum value of the waveform as shown in FIG. If the differential coefficient at that time is adjusted to be at least 2 or more, a waveform with a sharp edge (a waveform in which a noise component is suppressed) is obtained, and the measurement accuracy is further improved. In addition, there is a possibility that the detection of noise light may increase due to the reflection characteristics of the crystalline lens or vitreous body differing depending on the wavelength of the measurement light. It is effective in raising

  In the detection of the image position, it is possible to detect the image position from the peak position. However, as described above, the intermediate point of the waveform at the threshold S obtained by subtracting a predetermined luminance level from the peak value is used as the image position. By detecting, it is easy to obtain a stable measurement result. Also, when setting the threshold S, there is a large amount of variation even if the threshold S is too close to the peak, and even if the threshold S is too low, there is a high possibility that the variation will increase due to the influence of noise light. A position that avoids these is preferable.

  The SLD having a center wavelength of 850 nm to 940 nm is an ophthalmic apparatus that acquires the eye characteristics of the eye to be examined using low-coherent light, for example, an optical coherence tomography (OCT) using optical coherence tomography technology. It can also be applied as a light source. Conventionally, the ophthalmologic apparatus as described above has a problem that it is troublesome because the light from the light source can be seen when obtaining the eye characteristics. (For example, in the case of OCT, since the light emitted from the SLD light source scans in the vertical and horizontal directions at high speed, it is troublesome for the subject to see the scanning of the light.) By using an SLD with a center wavelength of 850 nm to 940 nm, the eye to be examined does not care about the light from the light source, the burden on the subject can be reduced, and the eye characteristics can be obtained with high accuracy. Note that when an SLD having a center wavelength of 850 nm to 940 nm is used in an optical coherence tomography (OCT), the resolution is considered to be lower than when an SLD having a center wavelength of around 830 nm is used. In this case, an SLD having a wide half-value width may be employed so as to compensate for the decrease in resolution.

  Next, a second embodiment using the eye refractive power measurement apparatus of the present invention will be described. Since the optical system and the control system are the same as those shown in FIG. 1, the details thereof are omitted, and here, the image data obtained by a plurality of imaging operations are added to each other, and the refractive power of the eye to be examined is calculated. A method for obtaining the value will be described. In the present embodiment, the number of addition processes is 1-2. In this case, a ring image is continuously picked up by the two-dimensional image pickup device 22, and a plurality of pieces of image data for performing addition processing are stored in the frame memory 71. Here, the one-time imaging time of the two-dimensional imaging element 22 is 1/30 seconds, for example, and imaging is performed at a predetermined interval (in this embodiment, 1/30 second interval), and the obtained image data Are sequentially output to the frame memory 71. In the present embodiment, the ring images thus captured will be described as a first image, a second image, and a third image in the order of shooting. Note that the image data is stored in the frame memory 71 as data representing the luminance level of each pixel imaged by the two-dimensional image sensor 22 from 0 to 255.

  First, the control unit 70 performs a first addition process on the image data in the first image and the image data in the second image (see FIG. 6A). Furthermore, the control unit 70 performs a second addition process on the image data after the first addition process and the image data in the third image (see FIG. 6B). In the present embodiment, it is determined whether or not the luminance signal level (measurement signal level) based on the image data after the addition processing saturates the detection limit, and the number of addition processing is controlled based on the determination result ( (See FIG. 7). That is, when it is determined that the peak of the luminance signal in the image data after the second addition process is completely saturated, the refractive power calculation process is performed based on the image data at the time when the first addition process is performed. I do. Note that the addition processing refers to processing for matching the coordinate positions of different image data and adding luminance levels.

  As described above, when the refraction value is calculated based on the measurement image (ring image) after performing the addition process, it is not necessary to obtain the measurement result by one photographing, and thus the first embodiment Thus, compared with the case where a measurement image is obtained by one imaging, the light quantity and imaging gain of the measurement light source can be lowered. Noise light can be further suppressed by setting the measurement light quantity and imaging gain low. In the present embodiment, a plurality of pieces of image data acquired by the two-dimensional light receiving element 22 are stored in the frame memory 71 and then the addition process is performed. However, the image data already stored in the frame memory 71 and A configuration may be adopted in which addition processing is performed by superimposing image data acquired later on the same memory area.

In addition, if the image data that has been subjected to addition processing immediately before the luminance signal is excessively saturated is applied as image data used when calculating the refractive power, the contrast between the ring image itself and the noise component becomes clearer. Measurement accuracy increases. Note that if the luminance signal is saturated too much by a plurality of addition processes, the image position is detected in a form containing a lot of noise components, which affects the measurement accuracy (see FIG. 8). However, if the luminance signal waveform is slightly saturated as shown in FIG. 9 (the peak position is saturated, but the saturated region is small), noise components that affect measurement accuracy are included. It's hard to get it. In order to determine whether it is slightly saturated or excessively saturated, for example, the number of pixels (width region W in FIGS. 8 and 9) corresponding to the position where the luminance signal in the predetermined meridian direction is saturated is within a predetermined allowable range (allowable). It may be determined based on whether or not the number is exceeded.
In the present embodiment, the number of addition processes is one to two. However, such a configuration can also be applied to a case where three or more addition processes are performed.

  It should be noted that when measuring a subject such as a small amount of reflected light from the fundus, the light quantity of the measurement light source 11 may be increased. In this case, the light amount may be increased based on the peak position of the distribution of the light amount level of the image data in the first image. Thereby, even a subject with little fundus reflected light can measure the refractive index.

  Further, as one example of modification of the second embodiment, a plurality of image data obtained by photographing is preliminarily removed by a subtraction process, and the image data from which the noise component has been removed is added. You can also. FIG. 10A shows the waveform of the luminance signal of the image data in the first image. Here, the control unit 70 performs a process of subtracting the low level component (hatched portion) of the image data. Thereby, the low noise component around the ring image can be removed. FIG. 10B is a diagram illustrating a waveform after performing the subtraction process. Similarly, the subtraction process is performed on the image data in the second image and the third image in advance, and then the addition process is performed with the noise component removed by adding the image data to each other. Therefore, it is possible to further avoid the influence of measurement error due to noise light.

  In this embodiment, addition processing is used. However, the accumulation time of the received light signal is variable, and the two-dimensional image sensor 22 that can accumulate for a long time is used. May be set to a predetermined time (for example, 100 ms at a time), and a ring image may be captured in a state where the amount of light source that causes noise light generation and the imaging gain of the two-dimensional imaging device are lowered. In this case, in order to obtain a measurement image immediately before saturation, for example, the control unit 70 analyzes a luminance signal in a predetermined meridian direction in image data when a ring image is captured, and gradually increases the accumulation time if the peak is low. The imaging may be repeated while increasing the length, and a predetermined measurement image may be obtained based on the refraction value. Further, if the ring image is excessively saturated, the imaging may be repeated while gradually shortening the accumulation time, and when a predetermined measurement image is obtained, the refraction value may be obtained based on this.

It is a schematic block diagram of the optical system and control system of the eye refractive power measuring apparatus of this embodiment. It is a figure explaining the structure of a ring lens. It is an example for demonstrating the wavelength sensitivity characteristic of a two-dimensional image sensor. It is a figure which shows a part of waveform of the luminance signal of a predetermined meridian direction. It is a figure for demonstrating the method to select based on the differential coefficient f 'of the waveform in the intermediate position vicinity of the peak and minimum value of a waveform. It is a figure for demonstrating an addition process. It is a flowchart explaining control of the frequency | count of an addition process. It is a figure when a luminance signal is saturated too much. It is a figure explaining when the waveform of a luminance signal is a slight saturation. It is a figure for demonstrating a subtraction process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Measurement optical system 10a Projection optical system 10b Light reception optical system 11 Measurement light source 20 Ring lens 22 Two-dimensional image sensor 30 Fixation target optical system 32 Fixation target 70 Control part 71 Frame memory

Claims (6)

In an eye refractive power measurement apparatus that objectively measures the eye refractive power of an eye to be examined, a projection optical system that includes a measurement light source that emits a light flux for measuring eye refractive power and projects the measurement light flux on the fundus of the eye to be examined, and A light receiving optical system that receives a reflected light beam from the fundus of the measurement light beam as a two-dimensional pattern image to the two-dimensional image sensor, and the two-dimensional pattern image received by the two-dimensional image sensor by the light receiving optical system. An eye refractive power measuring device, wherein the measuring light source is a super luminescent diode or a laser diode, the center wavelength of which is 850 to 940 nm. . The eye refractive power measuring device according to claim 1 obtains the intensity of a received light signal required for obtaining the eye refractive power from the two-dimensional pattern image received by the two-dimensional image sensor, and the two-dimensional image sensor. In order to suppress a received light signal that is a noise component included in the received two-dimensional pattern image, the two-dimensional image is obtained based on the wavelength region of the measurement light emitted from the measurement light source and the wavelength sensitivity characteristics of the two-dimensional image sensor. An eye refractive power measuring apparatus, wherein an imaging gain of an imaging element is set. 3. The eye refractive power measurement apparatus according to claim 2, wherein the two-dimensional pattern image received by the two-dimensional image sensor is a ring pattern image, and an imaging gain setting of the two-dimensional image sensor is an inner region of the two-dimensional pattern image. An eye refractive power measurement apparatus, which is performed so as to suppress a noise component generated in the eye. 3. The eye refractive power measurement apparatus according to claim 2, wherein the setting of the imaging gain is such that the waveform of each luminance signal at the time of detecting the position of the two-dimensional pattern image received by the two-dimensional imaging element is a boundary of the waveform peak. An eye refractive power measuring device is set so as to be symmetrical with respect to the left and right. The eye refractive power measurement apparatus according to claim 1 is based on image data that has been subjected to addition processing obtained by acquiring a plurality of two-dimensional pattern images captured by the two-dimensional light receiving element and adding the plurality of image data to each other. And an arithmetic processing means for obtaining the eye refractive power of the eye to be examined. 6. The eye refractive power measurement apparatus according to claim 5, wherein subtraction means for removing a measurement signal of a predetermined noise component in advance from each image data by subtraction before adding the image data to each other by the arithmetic processing means. An eye refractive power measuring device comprising: