CN114159020A - Refractometer, ophthalmological biological multi-parameter measuring instrument and measuring method - Google Patents
Refractometer, ophthalmological biological multi-parameter measuring instrument and measuring method Download PDFInfo
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Abstract
The invention relates to an optometry instrument and an ophthalmologic biological multi-parameter measuring instrument, which comprise a detection light source optical path system, a sample arm optical path system, a reference arm optical path system, a photoelectric detection acquisition system and an imaging system. A optometry instrument and a method for measuring ophthalmic biological multiparameters by an ophthalmic biological multiparameter measuring instrument comprise the following steps of firstly, acquiring signals of each part of an eye; step two, performing band-pass filtering processing on the signals; step three, performing Hilbert transform on the signal; step four, removing the frequency of the burr noise signal; and step five, calculating the distance between the corresponding signals. A method for measuring diopter by an optometry instrument and an ophthalmologic biological multi-parameter measuring instrument comprises the following steps of firstly, acquiring a reference light spot array image and a light spot array image to be measured by an imaging device; step two, noise suppression is carried out, and the centroid position of each light spot is obtained; step three, determining the offset of the centroid of the light spot; step four, calculating the wavefront slope; fifthly, fitting wavefront aberration; and step six, calculating the diopter of the human eyes.
Description
Technical Field
The invention relates to the field of optics, in particular to an optometry instrument, an ophthalmological biological multi-parameter measuring instrument and a measuring method.
Background
Myopia has become a major public health problem affecting the eye health of teenagers in China. According to the white paper published by the national visual health of the Beijing university China health development research center, the myopia in China becomes a national disease, and one person in every three persons is a myopia patient. The prevention and monitoring of myopia can effectively reduce the harm caused by myopia. At present, the main tools for vision screening are an optometry instrument and an ophthalmological biological multi-parameter measuring instrument, the refraction and astigmatism conditions of eyeballs are measured through the optometry instrument, and the ophthalmological biological multi-parameter measuring instrument judges true and false myopia.
An optometer is an important auxiliary medical detection means in ophthalmology or spectacle shops, and transmits a beam of infrared light source to pass through the cornea, crystalline lens and retina of human eyes, and then the infrared light source is reflected back to an optical system, and finally the optical signal is received by a camera and converted into an electric signal to obtain data such as a sphere lens, a cylindrical lens, an axial position and the like, and finally the diopter of the measured eye is obtained according to the data, so that accurate lens correction power is provided for ametropia of the eye.
The ophthalmic biological multiparameter measuring instrument is an instrument capable of simultaneously measuring the corneal length, anterior chamber depth, crystal thickness, vitreous body thickness and ocular axial length of an eye. The length of the axis of the eye plays a key role in judging the true and false myopia of the eyeball, and meanwhile, the health screening and development trend of the eyesight is well monitored, and generally, the myopia degree is increased by about 200-300 degrees when the length of the axis of the eye is increased by 1 mm; parameters such as corneal thickness, anterior chamber depth and lens thickness play a key role in calculating diopter before cataract extraction and intraocular artificial lens transplantation.
The prior technical patents of the ophthalmological biological multi-parameter measuring instrument mainly comprise an optical coherence biological measuring instrument and a method (CN 102551654B) for carrying out the biological measurement of eyes, and a system and a method (CN 102727172A) for measuring eyeball parameters by using a weak coherence technique to measure the thickness of the cornea, the thickness of the crystalline lens and the like of the eyes; the prior patent technology of the refractometer mainly comprises a refractometer (CN 110558931A), a full-automatic computerized refractometer (CN 111281333A) based on a Hartmann array, a medical refractometer and a refracturing method (CN 104274152A) thereof. These patents are all based on the unique technical function scheme of the eye biological parameter measuring instrument and the optometry instrument.
The existing ophthalmological biological multi-parameter measuring instrument can measure the cornea length, the anterior chamber depth, the crystal thickness, the vitreous body thickness and the eye axis length of an eye; refractometers are capable of measuring the refractive condition of the eye, but no instrument exists that combines the functions of both simultaneously.
Disclosure of Invention
Aiming at the technical problems in the prior art, one of the purposes of the invention is as follows: the utility model provides an optometry appearance and biological multi-parameter measuring apparatu of ophthalmology, it can realize that same instrument can both optometry and can carry out biological multi-parameter measurement of ophthalmology.
Aiming at the technical problems in the prior art, the second purpose of the invention is as follows: an optometry instrument and a method for measuring ophthalmic biological multiparameters by using the measuring instrument of the application are provided, which can realize the measurement of ophthalmic biological multiparameters by using the measuring instrument of the application.
Aiming at the technical problems in the prior art, the second purpose of the invention is as follows: a refractometer and a method for measuring diopter by an ophthalmological biological multi-parameter measuring instrument are provided, which can realize the measurement of human eye diopter by using the measuring instrument of the application.
In order to achieve the purpose, the invention adopts the following technical scheme:
an optometry instrument and an ophthalmological biological multi-parameter measuring instrument comprise a detection light source optical path system, a sample arm optical path system, a reference arm optical path system, a photoelectric detection acquisition system and an imaging system,
the detection light source optical system comprises a light source, a circulator and a coupler which are connected through optical fibers, wherein a light beam emitted by the light source enters the circulator through the optical fibers, part of light rays coming out of the circulator enter the 2 x 2 optical fiber coupler, and the ratio of the light rays in the light source optical system to the light rays coming out of the circulator is 50: the light splitting ratio of 50 emits light rays, and the light rays emitted by the optical fiber coupler respectively enter the sample arm light path system and the reference arm light path system;
the sample arm light path system comprises a first collimating mirror and a semi-reflecting and semi-transmitting mirror, light rays coming out of the optical fiber coupler are changed into parallel light through the first collimating mirror to be incident on eyes, a part of light rays reflected by the eyes and projected by the semi-reflecting and semi-transmitting mirror return to the optical fiber coupler in an original path,
the reference arm optical path system comprises a second collimator, an optical delay line, a cylindrical mirror and a reflector which are sequentially arranged along the light incidence direction, light rays coming out of the optical fiber coupler are changed into parallel light through the second collimator and enter the optical delay line, emergent light passing through the optical delay line is focused to the reflector through the cylindrical mirror, and the parallel light returns to the optical fiber coupler through the original path of the reflector;
the photoelectric detection acquisition system comprises a photoelectric balance detector, a data acquisition card and a processor, wherein light rays returned from the sample arm light path system and light rays returned from the reference arm light path system are received by the photoelectric balance detector after being interfered in the optical fiber coupler, the other part of light rays from the circulator enter the photoelectric balance detector, and the optical signals are converted into electric signals which are acquired by the data acquisition card and transmitted to the processor for signal analysis and processing;
the imaging system comprises a first focusing lens, a second focusing lens micro lens array and an imaging device, light reflected by eyes is focused by the semi-reflecting and semi-transparent mirror, becomes parallel light through the second focusing lens, is converged by the micro lens array and is received by the imaging device, and data received by the imaging device is transmitted to a processor for data processing.
The optical delay line is any one of a rotatable cube-shaped optical delay line, an optical delay line in which a stepping motor drives a mirror, or an optical delay line in which a rectangular prism is used.
Further, the light source is a broadband SLD light source, and the imaging device is a CCD camera.
A method for measuring ophthalmic biological multiparameters by an optometry instrument and an ophthalmic biological multiparameter measuring instrument comprises the following steps,
acquiring signals of each part of an eye according to the interference principle of a Michelson interferometer;
step two, performing band-pass filtering processing on interference signals of the cornea, the crystalline lens and the retina to remove frequency noise except the eye signals;
step three, performing Hilbert transform on the signal to extract the envelope of the signal;
removing the noise signal frequency of the burrs through low-pass filtering to obtain a pure peak signal;
and step five, calculating the distance between the corresponding signals by using the number between interference wave crests and wave troughs of the high-coherence light.
Further, the distance D between adjacent interference signal peaks can be expressed as,
in the formula: lambda [ alpha ]LIs the wavelength of the highly coherent laser light,
is the phase difference of the ranging interference signal between peaks, nLIs a wavelength lambdaLThe lower refractive index N is the number between the peaks and the troughs of the interference signal.
A method for measuring diopter by an optometry instrument and an ophthalmologic biological multi-parameter measuring instrument comprises the following steps,
acquiring a reference light spot array image and a light spot array image to be detected by using an imaging device;
step two, noise suppression is carried out on the reference light spot array image and the light spot array image to be detected through OSTU threshold segmentation, and the centroid position of each light spot is obtained;
step three, determining the offset of the centroid of the light spot;
step four, calculating the wavefront slope;
fifthly, fitting the wavefront aberration, and calculating the incident wavefront aberration and Zernike polynomial coefficients;
and step six, calculating the diopter of the human eyes.
Further, according to geometric optics, the relative displacement of the spot is proportional to the local slope at that point, so the wavefront slopes in the two orthogonal directions x and y are:
where W (x, y) is the incident wavefront aberration and f is the focal length of the microlens.
Further, the wavefront is represented by Zernike polynomials,
when formula (4) is substituted for formula (3) and formula (2), the following compounds can be obtained:
then, the following steps are carried out:
writing equations (7), (8), (9), (10) in the form of a matrix:
in the above matrix, wjThe matrix is a coefficient matrix of reconstructed wave front, and the above formula is written into by least square solution
β＝αω→αTβ＝αTαω→ω＝(αTα)-1αTβ＝α+β (11)
The wavefront aberration of the human eye can be reconstructed by solving Zernike polynomial coefficients, and the refractive power can be calculated according to the following formula:
wherein R is pupil radius, C is cylinder power, S is sphere power, and omega 4, omega 5, omega 6 are Zernike polynomial coefficients.
In summary, the present invention has the following advantages:
the utility model provides an optometry appearance and biological multi-parameter measuring apparatu of ophthalmology, includes detection light source optical path system, sample arm optical path system, reference arm optical path system, photoelectric detection collection system and imaging system, its simple structure, rationally distributed, according to michelson interferometer interference principle, can realize that same platform instrument can reach optometry and also can carry out the biological multi-parameter measurement of ophthalmology.
A optometry instrument and a method for measuring ophthalmic biological multiparameters by an ophthalmic biological multiparameter measuring instrument comprise the following steps of firstly, acquiring signals of each part of an eye according to the interference principle of a Michelson interferometer; step two, performing band-pass filtering processing on interference signals of the cornea, the crystalline lens and the retina to remove frequency noise except the eye signals; step three, performing Hilbert transform on the signal to extract the envelope of the signal; removing the noise signal frequency of the burrs through low-pass filtering to obtain a pure peak signal; and step five, calculating the distance between the corresponding signals by using the number between interference wave crests and wave troughs of the high-coherence light. By adopting the method, the measuring instrument can be used for measuring the ophthalmic biological multi-parameter, and the accuracy of measured data is high.
A method for measuring diopter by an optometry instrument and an ophthalmologic biological multi-parameter measuring instrument comprises the following steps of firstly, acquiring a reference light spot array image and a light spot array image to be measured by using an imaging device; step two, noise suppression is carried out on the reference light spot array image and the light spot array image to be detected through OSTU threshold segmentation, and the centroid position of each light spot is obtained; step three, determining the offset of the centroid of the light spot; step four, calculating the wavefront slope; fifthly, fitting the wavefront aberration, and calculating the incident wavefront aberration and Zernike polynomial coefficients; and step six, calculating the diopter of the human eyes. By adopting the method, the measuring instrument can be used for measuring the diopter of human eyes, and the measurement is more accurate.
Drawings
Fig. 1 is a schematic structural diagram of an optometry instrument and an ophthalmologic biological multi-parameter measuring instrument of the invention.
Figure 2 is a diagram of the cornea and interference signals.
FIG. 3 is a diagram of a corneal signal after low pass filtering.
Fig. 4 is a graph of a corneal signal after hilbert transform.
Fig. 5 is a graph of the low pass filtered noise signal frequency with the spur removed, resulting in a clean peak signal.
Fig. 6 is a diagram of ophthalmic biological multi-parameter measurement.
FIG. 7 is a graph of H-S speckle for an ideal wavefront.
Fig. 8 is a flowchart of an algorithm for finding eye diopter.
Figure 9 is a diagram of wavefront aberration offset.
Wherein, fig. 1 includes:
1-broadband SLD light source, 2-optical fiber, 3-circulator, 4-optical fiber coupler, 5-first collimating mirror, 6-semi-reflecting semi-transparent mirror, 7-eye, 8-first focusing lens, 9-second focusing lens, 10-microlens array, 11-CCD camera, 12-second collimating mirror, 13-optical delay line, 14-cylindrical mirror, 15-reflector, 16-photoelectric balance detector, 17-data acquisition card, 18-computer processing terminal.
Detailed Description
The present invention will be described in further detail below.
As shown in figure 1, the optometry instrument and the ophthalmology biological multi-parameter measuring instrument comprise a detection light source optical path system, a sample arm optical path system, a reference arm optical path system, a photoelectric detection acquisition system and an imaging system,
the detection light source optical system comprises a light source, a circulator and a coupler which are connected through optical fibers, wherein a light beam emitted by the light source enters the circulator through the optical fibers, part of light rays coming out of the circulator enter the 2 x 2 optical fiber coupler, and the ratio of the light rays in the light source optical system to the light rays coming out of the circulator is 50: the light splitting ratio of 50 emits light rays, and the light rays emitted by the optical fiber coupler respectively enter the sample arm light path system and the reference arm light path system;
the sample arm light path system comprises a first collimating mirror and a semi-reflecting and semi-transmitting mirror, light rays coming out of the optical fiber coupler are changed into parallel light through the first collimating mirror to be incident on eyes, a part of light rays reflected by the eyes and projected by the semi-reflecting and semi-transmitting mirror return to the optical fiber coupler in an original path,
the reference arm optical path system comprises a second collimator, an optical delay line, a cylindrical mirror and a reflector which are sequentially arranged along the light incidence direction, light rays coming out of the optical fiber coupler are changed into parallel light through the second collimator and enter the optical delay line, emergent light passing through the optical delay line is focused to the reflector through the cylindrical mirror, and the parallel light returns to the optical fiber coupler through the original path of the reflector;
the photoelectric detection acquisition system comprises a photoelectric balance detector, a data acquisition card and a processor, wherein light rays returned from the sample arm light path system and light rays returned from the reference arm light path system are received by the photoelectric balance detector after being interfered in the optical fiber coupler, the other part of light rays from the circulator enter the photoelectric balance detector, and the optical signals are converted into electric signals which are acquired by the data acquisition card and transmitted to the processor for signal analysis and processing; the imaging system comprises a first focusing lens, a second focusing lens micro lens array and an imaging device, light reflected by eyes is focused by the semi-reflecting and semi-transparent mirror, becomes parallel light through the second focusing lens, is converged by the micro lens array and is received by the imaging device, and data received by the imaging device is transmitted to a processor for data processing. The optical delay line is any one of a rotatable cube-shaped optical delay line, an optical delay line of a stepping motor driven mirror, or an optical delay line of a right-angle prism. The light source is a broadband SLD light source, and the imaging device is a CCD camera.
The measurement of the biological multiparameter measuring instrument for ophthalmology is realized by utilizing a rotary square block to generate an optical delay line, so that the optical path can be quickly changed, and the real-time axial scanning is carried out on the eyes. Light from the sample arm is incident on the eye and returns through the cornea, lens and retina reflections and interferes with the light from the reference arm. When a low coherence light source is used, the detector receives the maximum amount of energy only when the optical path difference between the reference arm and the sample arm is zero. The specific process comprises the following steps: the lengths of optical fibers from the broadband SLD light source to the first collimating mirror and the second collimating mirror are equal, so that the optical fiber optical distances of the sample arm and the reference arm are equal; then the optical path from the first collimating mirror to the cornea of the eye is controlled to be equal to the optical path from the second collimating mirror to the reflecting mirror, so that the optical path difference of the two arms is ensured to be 0, and the eye can be scanned by rotating the square block.
A optometry instrument and a method for measuring ophthalmic biological multiparameters by an ophthalmic biological multiparameter measuring instrument comprise the following steps of firstly, acquiring signals of each part of an eye according to the interference principle of a Michelson interferometer; step two, performing band-pass filtering processing on interference signals of the cornea, the crystalline lens and the retina to remove frequency noise except the eye signals; step three, performing Hilbert transform on the signal to extract the envelope of the signal; removing the noise signal frequency of the burrs through low-pass filtering to obtain a pure peak signal; and step five, calculating the distance between the corresponding signals by using the number between interference wave crests and wave troughs of the high-coherence light. Specifically, as shown in fig. 2, the interference signal of the cornea is a sine wave, and we need to process the signal. The specific process comprises the following steps: firstly, performing band-pass filtering processing on interference signals of a cornea, a crystalline lens and a retina to remove frequency noise except an eye signal, as shown in fig. 3; then, performing Hilbert transform on the signal to extract an envelope of the signal, wherein the signal is shown in FIG. 4; the extracted envelope has a certain burr, and finally the noise signal frequency of the burr is removed through low-pass filtering to obtain a pure peak signal, as shown in fig. 5; and finally, calculating the distance between corresponding signals by using the number between interference peaks and troughs of the high-coherence light as shown in fig. 6. The distance D between adjacent interference signal peaks can be expressed as,
in the formula: lambda [ alpha ]LIs the wavelength of the highly coherent laser light,
is the phase difference of the ranging interference signal between peaks, nLIs a wavelength lambdaLIs as followsThe refractive index N is the number between the wave crests and the wave troughs of the interference signal.
A method for measuring diopter by an optometry instrument and an ophthalmologic biological multi-parameter measuring instrument comprises the following steps of firstly, acquiring a reference light spot array image and a light spot array image to be measured by using an imaging device; step two, noise suppression is carried out on the reference light spot array image and the light spot array image to be detected through OSTU threshold segmentation, and the centroid position of each light spot is obtained; step three, determining the offset of the centroid of the light spot; step four, calculating the wavefront slope; fifthly, fitting the wavefront aberration, and calculating the incident wavefront aberration and Zernike polynomial coefficients; and step six, calculating the diopter of the human eyes.
The light reflected by the eye is partially reflected by the semi-reflective semi-transparent mirror and returns to the first focusing lens for focusing, and then is changed into parallel light by the second focusing lens, the parallel light is converged on the CCD camera by the micro lens array, and when an ideal plane wave passes through the micro lens array, the wave front is focused on the focal plane of the micro lens to form a light spot array, as shown in FIG. 7.
When the aberrated wavefront passes through the microlens array, the array of spots focused at the focal plane will be shifted. Therefore, the relative shift amount deltax and deltay of each microlens in the x and y directions can be calculated by comparing the ideal plane wave with the spot array with the wave front with aberration. The method comprises the steps of obtaining a light spot array image by using a CCD camera, carrying out noise suppression through OSTU threshold segmentation, obtaining the centroid position of each light spot, and then determining the centroid offset of each light spot so as to calculate the wavefront slope. The algorithm flow chart is shown in fig. 8:
as shown in fig. 9, according to geometric optics, the relative displacement of the spot is proportional to the local slope at that point, so the wavefront slopes in the x and y orthogonal directions are:
where W (x, y) is the incident wavefront aberration and f is the focal length of the microlens.
In order to avoid errors caused by the fact that the various equations influence each other due to the lack of orthogonality in the process of fitting the wavefront aberration, the selected wavefront reconstruction algorithm needs the polynomial to have the orthogonal characteristic and the optical aberration correspondence, and therefore the Zernike polynomial is selected as the wavefront reconstruction algorithm. The wavefront is represented by Zernike polynomials,
when formula (4) is substituted for formula (3) and formula (2), the following compounds can be obtained:
then, the following steps are carried out:
writing equations (7), (8), (9), (10) in the form of a matrix:
in the above matrix, wjThe matrix is a coefficient matrix of reconstructed wave front, and the above formula is written into by least square solution
β＝αω→αTβ＝αTαω→ω＝(αTα)-1αTβ＝α+β (11)
The wavefront aberration of the human eye can be reconstructed by solving Zernike polynomial coefficients, and the refractive power can be calculated according to the following formula:
wherein R is pupil radius, C is cylinder power, S is sphere power, and omega 4, omega 5, omega 6 are Zernike polynomial coefficients.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (8)
1. An optometry instrument and an ophthalmological biological multi-parameter measuring instrument are characterized in that: comprises a detection light source optical path system, a sample arm optical path system, a reference arm optical path system, a photoelectric detection acquisition system and an imaging system,
the detection light source optical system comprises a light source, a circulator and a coupler which are connected through optical fibers, wherein a light beam emitted by the light source enters the circulator through the optical fibers, part of light rays coming out of the circulator enter the 2 x 2 optical fiber coupler, and the ratio of the light rays in the light source optical system to the light rays coming out of the circulator is 50: the light splitting ratio of 50 emits light rays, and the light rays emitted by the optical fiber coupler respectively enter the sample arm light path system and the reference arm light path system;
the sample arm light path system comprises a first collimating mirror and a semi-reflecting and semi-transmitting mirror, light rays coming out of the optical fiber coupler are changed into parallel light through the first collimating mirror to be incident on eyes, a part of light rays reflected by the eyes and projected by the semi-reflecting and semi-transmitting mirror return to the optical fiber coupler in an original path,
the reference arm optical path system comprises a second collimator, an optical delay line, a cylindrical mirror and a reflector which are sequentially arranged along the light incidence direction, light rays coming out of the optical fiber coupler are changed into parallel light through the second collimator and enter the optical delay line, emergent light passing through the optical delay line is focused to the reflector through the cylindrical mirror, and the parallel light returns to the optical fiber coupler through the original path of the reflector;
the photoelectric detection acquisition system comprises a photoelectric balance detector, a data acquisition card and a processor, wherein light rays returned from the sample arm light path system and light rays returned from the reference arm light path system are received by the photoelectric balance detector after being interfered in the optical fiber coupler, the other part of light rays from the circulator enter the photoelectric balance detector, and the optical signals are converted into electric signals which are acquired by the data acquisition card and transmitted to the processor for signal analysis and processing;
the imaging system comprises a first focusing lens, a second focusing lens micro lens array and an imaging device, light reflected by eyes is focused by the semi-reflecting and semi-transparent mirror, becomes parallel light through the second focusing lens, is converged by the micro lens array and is received by the imaging device, and data received by the imaging device is transmitted to a processor for data processing.
2. An optometry and ophthalmic biological multiparameter measuring instrument according to claim 1, wherein: the optical delay line is any one of a rotatable cube-shaped optical delay line, an optical delay line of a stepping motor driven mirror, or an optical delay line of a right-angle prism.
3. An optometry and ophthalmic biological multiparameter measuring instrument according to claim 1, wherein: the light source is a broadband SLD light source, and the imaging device is a CCD camera.
4. A method of measuring ophthalmic biological multiparameters using an optometry and ophthalmic biological multiparameter measuring instrument according to any one of claims 1 to 3, wherein: comprises the following steps of (a) carrying out,
acquiring signals of each part of an eye according to the interference principle of a Michelson interferometer;
step two, performing band-pass filtering processing on interference signals of the cornea, the crystalline lens and the retina to remove frequency noise except the eye signals;
step three, performing Hilbert transform on the signal to extract the envelope of the signal;
removing the noise signal frequency of the burrs through low-pass filtering to obtain a pure peak signal;
and step five, calculating the distance between the corresponding signals by using the number between interference wave crests and wave troughs of the high-coherence light.
5. The method of claim 4 for measuring ophthalmic biological multiparameters with an optometry and ophthalmic biological multiparameter measuring instrument, wherein: the distance D between adjacent interference signal peaks can be expressed as,
in the formula: lambda [ alpha ]LIs the wavelength of the highly coherent laser light,
is the phase difference of the ranging interference signal between peaks, nLIs a wavelength lambdaLThe lower refractive index N is the number between the peaks and the troughs of the interference signal.
6. A method of measuring diopter with an optometry and ophthalmic bioparameter according to any one of claims 1 to 3, characterized in that: comprises the following steps of (a) carrying out,
acquiring a reference light spot array image and a light spot array image to be detected by using an imaging device;
step two, noise suppression is carried out on the reference light spot array image and the light spot array image to be detected through OSTU threshold segmentation, and the centroid position of each light spot is obtained;
step three, determining the offset of the centroid of the light spot;
step four, calculating the wavefront slope;
fifthly, fitting the wavefront aberration, and calculating the incident wavefront aberration and Zernike polynomial coefficients;
and step six, calculating the diopter of the human eyes.
7. A method of measuring diopter with an optometry and ophthalmic bioparameter according to claim 6, wherein: according to geometric optics, the relative displacement of the spot is proportional to the local slope at that point, so the wavefront slopes in the two orthogonal directions x and y are:
where W (x, y) is the incident wavefront aberration and f is the focal length of the microlens.
8. A method of measuring diopter with an optometry and ophthalmic bioparameter according to claim 7, wherein: the wavefront is represented by Zernike polynomials,
when formula (4) is substituted for formula (3) and formula (2), the following compounds can be obtained:
then, the following steps are carried out:
writing equations (7), (8), (9), (10) in the form of a matrix:
in the above matrix, wjThe matrix is a coefficient matrix of reconstructed wave front, and the above formula is written into by least square solution
β＝αω→αTβ＝αTαω→ω＝(αTα)-1αTβ＝α+β (11)
The wavefront aberration of the human eye can be reconstructed by solving Zernike polynomial coefficients, and the refractive power can be calculated according to the following formula:
wherein R is pupil radius, C is cylinder power, S is sphere power, and omega 4, omega 5, omega 6 are Zernike polynomial coefficients.
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