Method and apparatus for measuring retinal topography

Abstract

The application discloses a kind of retinal refractive topography measurement method and device, method includes: by wavefront signal light source, wavefront signal is sent to the retina to be measured, and part of component in scanning component is moved, the position of wavefront signal is incident to the retina to be measured is adjusted;By wavefront detector, the wavefront signal reflected by different positions of the retina to be measured is received, and the corresponding wavefront signal map is formed for each position reflected wavefront signal, obtain the multiple wavefront signal map corresponding to multiple positions;By topographic map generation module, multiple wavefront signal maps are respectively image-processed, obtain the corresponding multiple wavefront aberration values, and multiple wavefront aberration values are mapped to the corresponding position in multiple positions, generate retinal refractive topography.

Description

Technical Field

[0001] This application relates to the field of retinal measurement technology, and in particular to a method and apparatus for measuring retinal refractive topography. Background Technology

[0002] Refractive topography can be used to predict the onset and progression of myopia in advance and accurately, scientifically evaluate the effectiveness of various myopia prevention and control methods, and precisely guide refractive treatments such as orthokeratology lenses, multifocal contact lenses, and excimer laser surgery. Measurements of refractive topography can typically be performed using either moiré fringe-based or fundus imaging-based methods. However, the moiré fringe method is complex due to limitations in grating fabrication and the principle that the grating should be as close as possible to the object being measured (i.e., the human eye). Fundus imaging-based methods acquire multi-angle refractive information of the retina through mechanical zoom, but the measurement time is usually long, and the risk of measurement error due to the subject's eye movements is high. Summary of the Invention

[0003] This application aims to provide a method and apparatus for measuring retinal refractive topography.

[0004] The technical solution of this application embodiment is implemented as follows:

[0005] This application provides a method for measuring retinal refractive topography, and an apparatus for measuring retinal refractive topography, the apparatus including a wavefront signal source, a wavefront detector, a scanning component, and a topography generation module; the scanning component is located in the optical path between the wavefront signal source and the wavefront detector; the method includes:

[0006] A wavefront signal is sent to the retina under test using a wavefront signal light source, and the scanning assembly and / or some components in the scanning assembly are moved to adjust the position of the wavefront signal incident on the retina under test.

[0007] The wavefront detector receives wavefront signals reflected from different positions on the retina under test, and forms a corresponding wavefront signal map for each position, thus obtaining multiple wavefront signal maps for multiple positions.

[0008] The topographic map generation module processes multiple wavefront signal maps to obtain multiple corresponding wavefront aberration values, and maps these wavefront aberration values ​​to corresponding locations in multiple positions to generate a retinal refractive topographic map.

[0009] This application provides a device for measuring retinal refractive topography, including a wavefront signal source, a wavefront detector, a scanning component, and a topography generation module; the scanning component is located in the optical path between the wavefront signal source and the wavefront detector.

[0010] A wavefront signal source is used to send wavefront signals to the retina under test;

[0011] A moving module is used to move the scanning assembly and / or some components of the scanning assembly to adjust the position of the wavefront signal incident on the retina to be tested;

[0012] A wavefront detector is used to receive wavefront signals reflected from different positions on the retina under test, and to form a corresponding wavefront signal map for the wavefront signal reflected from each position, thus obtaining multiple wavefront signal maps corresponding to multiple positions.

[0013] The topographic map generation module is used to perform image processing on multiple wavefront signal maps to obtain multiple corresponding wavefront aberration values, and to map the multiple wavefront aberration values ​​to corresponding locations in multiple locations to generate a retinal refractive topographic map.

[0014] This application provides a method and apparatus for measuring retinal refractive topography. The method includes: sending a wavefront signal to the retina under test via a wavefront signal light source, and moving a scanning component and / or a portion thereof to adjust the position of the wavefront signal incident on the retina; receiving wavefront signals reflected from different positions on the retina under test via a wavefront detector, and forming a corresponding wavefront signal map for each reflected wavefront signal, resulting in multiple wavefront signal maps corresponding to multiple positions; and performing image processing on the multiple wavefront signal maps via a topography generation module to obtain multiple corresponding wavefront aberration values, and mapping the multiple wavefront aberration values ​​to corresponding positions among the multiple locations to generate a retinal refractive topography. The technical solution provided in this application simplifies the complexity of optical system design while improving measurement efficiency and reducing the risk of measurement errors by moving the scanning component to scan different positions on the retina. Attached Figure Description

[0015] Figure 1 A schematic flowchart illustrating a method for measuring retinal refractive topography provided in this application embodiment;

[0016] Figure 2 A schematic diagram of the structure of an exemplary retinal refractive topography measuring device provided in this application embodiment. Figure 1 ;

[0017] Figure 3 A schematic flowchart illustrating an exemplary moving scanning component provided in an embodiment of this application;

[0018] Figure 4 A schematic diagram illustrating an exemplary path for implementing whole-retinal scanning, provided for embodiments of this application;

[0019] Figure 5(a) is a top view of an exemplary plane mirror and spherical mirror provided in an embodiment of this application;

[0020] Figure 5(b) is an exemplary view diagram of a plane mirror and a spherical mirror provided in an embodiment of this application;

[0021] Figure 6 A schematic diagram illustrating an exemplary process for reflecting a wavefront signal, provided as an embodiment of this application;

[0022] Figure 7 A schematic diagram illustrating an exemplary process for determining wavefront aberration values ​​is provided for an embodiment of this application.

[0023] Figure 8 A schematic diagram of an exemplary wavefront signal provided for an embodiment of this application;

[0024] Figure 9 A schematic diagram illustrating an exemplary basis for determining wavefront aberrations, provided for an embodiment of this application;

[0025] Figure 10 A schematic flowchart for determining the actual centroid is provided in this application embodiment. Figure 1 ;

[0026] Figure 11 A schematic flowchart for determining the actual centroid is provided in this application embodiment. Figure 2 ;

[0027] Figure 12 A schematic flowchart illustrating an exemplary method for measuring retinal refractive topography provided in this application embodiment;

[0028] Figure 13 A schematic diagram of the structure of an exemplary retinal refractive topography measuring device provided in this application embodiment. Figure 2 . Detailed Implementation

[0029] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. It is understood that the specific embodiments described herein are merely for explaining the relevant application and not for limiting the application. Furthermore, it should be noted that, for ease of description, only the parts relevant to the application are shown in the accompanying drawings.

[0030] This application provides a method for measuring retinal refractive topography, implemented by a retinal refractive topography measuring device. The measuring device includes a wavefront signal source, a wavefront detector, a scanning component, and a topography generation module; the scanning component is located in the optical path between the wavefront signal source and the wavefront detector; as... Figure 1As shown, the process includes the following steps S101 to S103:

[0031] Step S101: Send a wavefront signal to the retina under test through a wavefront signal light source, and move the scanning component and / or some components in the scanning component to adjust the position of the wavefront signal incident on the retina under test.

[0032] In the embodiments of this application, the retina to be tested can be a human eye, or of course, the eye of other animals with retinal structures; this application does not limit this.

[0033] In the embodiments of this application, the wavefront signal light source is a device or tool capable of generating a signal with specific wavefront characteristics.

[0034] In the embodiments of this application, the measuring device for retinal refractive topography is an electronic device with retinal refractive topography measurement function, exemplarily, such as... Figure 2 As shown, the retinal refractive topography measurement device 20 may include: a wavefront signal source 21, a wavefront detector 22, a scanning component 23, and a topography generation module 24, wherein the scanning component 23 is located in the optical path between the wavefront signal source 21 and the wavefront detector 22.

[0035] In the embodiments of this application, the retinal refractive topography measuring device sends a wavefront signal to the retina to be tested through a wavefront signal light source. While sending the wavefront signal, the scanning component or part of the scanning component is moved so that the wavefront signal can be incident on different positions of the retina to be tested from different directions and angles.

[0036] In the embodiments of this application, the measuring device for retinal refractive topography can move the entire scanning assembly, or move some components of the scanning assembly, or move them simultaneously; regardless of the method of movement, the purpose is to complete a full scan of the retina to be tested.

[0037] In the embodiments of this application, the moving scanning component and / or part of the scanning component of the retinal refractive topography measuring device are used to perform a full-range scan of the retina under test in order to obtain the refractive topography corresponding to the retina under test.

[0038] Step S102: Receive wavefront signals reflected from different positions of the retina under test using a wavefront detector, and form a corresponding wavefront signal map for each position, thus obtaining multiple wavefront signal maps corresponding to multiple positions.

[0039] In the embodiments of this application, after the wavefront signal is incident on the retina to be tested, it will be reflected out. At this time, the testing device receives the wavefront signals reflected from different positions of the retina to be tested through the wavefront detector, and forms a corresponding wavefront signal map based on the wavefront signal reflected from each position. In this way, each position corresponds to a wavefront signal map. After scanning the retina to be tested at multiple positions based on the wavefront signal through the scanning component, multiple wavefront signal maps can be obtained.

[0040] In the embodiments of this application, the wavefront signal map is a map formed by a distorted array of discrete light spots distributed across a dotted array received by the wavefront detector. After the measuring device acquires wavefront signal maps at different locations on the retina under test, it generates a retinal refractive topography map based on the wavefront signal maps at different locations.

[0041] Step S103: The topographic map generation module performs image processing on multiple wavefront signal maps to obtain corresponding wavefront aberration values, and maps these wavefront aberration values ​​to corresponding locations in multiple locations to generate a retinal refractive topographic map.

[0042] In the embodiments of this application, the measuring device performs image processing on each of the multiple wavefront signal maps through the topographic map generation module. In this way, each wavefront signal map will obtain a corresponding wavefront aberration value. Since each wavefront signal map is a signal map for the corresponding position on the retina to be tested, the measuring device can map multiple wavefront aberration values ​​to the corresponding positions among multiple positions on the retina to be tested based on the position, so as to generate a retinal refractive topographic map.

[0043] In the embodiments of this application, the retinal refractive topography map can be generated using software capable of creating three-dimensional topographic maps. For example, the retinal refractive topography map can be a three-dimensional mesh map or a three-dimensional shading surface map.

[0044] Compared to the complex and less accurate measurement systems in the prior art, the present application uses a moving scanning component to scan different positions on the retina, which simplifies the complexity of the optical system design, improves measurement efficiency, and reduces the risk of measurement errors.

[0045] In some embodiments, the scanning assembly includes a plane mirror and a scanning support; the plane mirror is mounted on the scanning support, and the measuring device performs the above step S101 of "moving the scanning assembly and / or a portion of the scanning assembly to adjust the position of the wavefront signal incident on the retina to be measured," as shown in the example. Figure 3 As shown, the process may include the following steps S301 and S302:

[0046] Step S301: Control the plane mirror to rotate multiple times within a preset angle around the central axis of the plane mirror, and project the wavefront signal into the retina to be tested through the plane mirror; wherein, the central axis is perpendicular to the direction in which the wavefront signal is sent by the wavefront signal source.

[0047] For example, such as Figure 2 As shown, the scanning assembly 23 also includes a plane mirror 231 and a scanning bracket 232.

[0048] In the embodiments of this application, the measuring device can control a plane mirror to rotate multiple times around the central axis of the plane mirror within a preset angle. The preset angle is a pre-set angle capable of scanning the entire retina to be measured, and can be ±45 degrees, ±90 degrees, or other angles. The specific preset angle can be set based on actual needs and applications, and this application does not limit it.

[0049] In the embodiments of this application, the measuring device can control a plane mirror to rotate around the central axis of the plane mirror within a preset angle so that the wavefront signal sent by the wavefront signal light source can complete a single line scan of the retina to be measured.

[0050] In the embodiments of this application, the central axis is perpendicular to the direction in which the wavefront signal is transmitted by the wavefront signal light source, so that the measuring device can make the wavefront signal that hits the plane mirror be emitted in a different direction.

[0051] Step S302: After each rotation of the plane mirror, control the scanning support to move in a direction perpendicular to the central axis within a preset range; wherein, the direction of movement of the scanning support is opposite when the plane mirror rotates twice consecutively.

[0052] In the embodiments of this application, the measuring device controls the movement within a preset range between scans whenever the plane mirror rotates at a preset angle. The preset range is set in order to scan the entire range of the retina to be tested.

[0053] In the embodiments of this application, the plane mirror rotates once at a preset angle to complete one line scan of the retina to be tested, while the scanning bracket moves within a preset range to complete the process of the retina to be tested from line scan to area scan. The direction of the scanning bracket movement is opposite when the plane mirror rotates twice in succession, so as not to waste the movement time between scans, that is, each movement can realize scanning.

[0054] In the embodiments of this application, the scanning support is controlled to move along a direction perpendicular to the central axis within a preset range. The step size of each movement depends on the set scanning interval. If a higher accuracy of the retinal scan is required, the step size can be set to be smaller. If a lower accuracy of the retinal scan is required, the step size can be set to be larger. The specific step size setting can be set based on actual needs and application scenarios, and this application does not limit it.

[0055] For example, such as Figure 4 As shown, the plane mirror rotates once within a preset angle to achieve one line scan (see...). Figure 4 (401) In the scan, moving one step within a preset range between scans can achieve another line scan, thus achieving a surface scan. The scan path is as follows: Figure 4 As shown in 402.

[0056] In the embodiments of this application, the measuring device may also be configured to move only the plane mirror while the entire scanning component remains stationary. In this case, the plane mirror needs to move in at least two directions so that an angle is also reflected on another central axis perpendicular to the plane mirror, thus achieving a full scan of the retina under test. Alternatively, the testing device may be configured to keep the plane mirror stationary while the scanning component moves. In this case, the scanning component will also move in another vertical direction in addition to the aforementioned moving direction, thus also achieving a full scan of the retina under test.

[0057] As shown in Figure 5(a), a top view of a scanning component is provided. It can be seen that the plane mirror 231 can rotate 360°, but in this application, it is not necessary to rotate in this way, or it can also rotate 360 ​​degrees. In this way, for every 180 degrees of rotation, the scanning bracket moves one step within a preset range.

[0058] Compared to related technologies that require the entire measuring device to be moved, this application achieves a full scan of the retina by moving the scanning component, which simplifies the complexity of the optical system design.

[0059] In some embodiments, the scanning assembly further includes a spherical mirror; the spherical mirror is mounted on the scanning bracket; the center of the spherical mirror is located on the central axis; when the measuring device performs the above step S301 of "injecting the wavefront signal into the retina to be tested through the plane mirror", it may further include the following steps: using the plane mirror to reflect the wavefront signal to the spherical mirror, and using the spherical mirror to inject the reflected wavefront signal into the retina to be tested.

[0060] In the embodiments of this application, such as Figure 2 As shown, the scanning component 23 may also include a spherical mirror 233, the center of which is located on the central axis.

[0061] As shown in Figure 5(a), the center 2331 of the spherical mirror 233 is located on the central axis of the plane mirror 231. As shown in Figure 5(b), a side view diagram of the plane mirror and spherical mirror in a scanning assembly is provided, showing that the light passes from the plane mirror to the spherical mirror and is then reflected onto the retina to be tested.

[0062] In the embodiments of this application, the wavefront signal first passes through a plane mirror, and then is reflected to a spherical mirror. Since the distance of the plane mirror relative to the distance of the received wavefront signal is different, the spherical mirror is set here to ensure that the light beam always reaches every point on the retinal surface at the same distance, and can be accurately focused at each point, avoiding beam distortion and improving the accuracy of scanning and measurement.

[0063] In some embodiments, the scanning bracket has a light-transmitting aperture; when the measuring device performs the above step "using a spherical mirror to project the reflected wavefront signal into the retina to be tested", it can perform the following steps: using a spherical mirror, project the reflected wavefront signal into the retina to be tested through the light-transmitting aperture.

[0064] In the embodiments of this application, the scanning bracket is provided with a light-transmitting aperture, for example, such as Figure 2 As shown, the light-transmitting aperture 234 is mounted on the scanning bracket 232.

[0065] In the embodiments of this application, the wavefront signal reflected by the spherical mirror can be transmitted into the retina to be tested through the light-transmitting aperture.

[0066] The scanning component provided in this application embodiment can achieve full retinal scanning through rotation and translation devices, which reduces the design complexity to a certain extent.

[0067] In some embodiments, the testing apparatus further includes: a pupil imaging group, a beam splitter, a relay lens group, and an imaging lens group; when the measuring device performs the above step S102 "receiving wavefront signals reflected from different positions of the retina under test via a wavefront detector", such as Figure 6 As shown, the following steps S601 and S602 can be performed:

[0068] Step S601: Using a beam splitter, the wavefront signals reflected from different positions of the retina to be tested are directed into the pupil imaging group and the relay lens group respectively; the pupil imaging group is used for aiming or corneal curvature measurement based on the wavefront signals reflected from different positions.

[0069] In the embodiments of this application, such as Figure 2 As shown, the measuring device 20 also includes a pupil imaging group 25, a beam splitter 26, a relay lens group 27, and an imaging lens group 28.

[0070] In the embodiments of this application, the measuring device can use a beam splitter to send wavefront signals reflected from different positions of the retina to be measured into the pupil imaging group and the relay lens group respectively. It should be noted that the signals sent into the pupil imaging group and the relay lens group are the same.

[0071] In embodiments of this application, the pupil imaging group is used for real-time aiming based on wavefront signals reflected from different positions or for corneal curvature measurement.

[0072] in, Figure 2 The image only shows that the pupil imaging group has two imaging lenses (252 and 253). It should be noted that multiple imaging lenses can be set in the pupil imaging group. The specific number of imaging lenses can be designed based on actual needs and application scenarios. For example, if high accuracy is required, more lenses can be set.

[0073] Step S602: The wavefront signal propagated by the beam splitter is transmitted to the wavefront detector via the imaging mirror group through the relay mirror group.

[0074] In the embodiments of this application, the measuring device transmits the wavefront signal propagated by the beam splitter to the wavefront detector via the imaging lens group through the relay lens group.

[0075] like Figure 2 As shown, a beam splitter 29 is also provided between the relay mirror group 27 and the imaging mirror group 28. This beam splitter is used to direct the wavefront signal into the retina under test and to direct the signal reflected back from the retina into the imaging mirror group, which then directs it into the wavefront detector.

[0076] In the embodiments of this application, the wavefront detector can be a Hartmann wavefront detector, which includes a microlens array. This wavefront detector has a fast response speed and can monitor changes in the light wavefront in real time, making it suitable for the measurement and monitoring of dynamic wavefronts. The Hartmann wavefront detector has a simple structure, good flexibility, and strong adaptability. It does not require a reference light or a strictly dark room environment during operation, adapting to various environmental conditions. Furthermore, the full-field scanning of the retina via a scanning mechanism greatly simplifies the complexity of the optical system design. Hartmann wavefront analysis can accurately measure the distortion of the light wavefront, with a measurement accuracy reaching a fraction of the wavelength or even higher.

[0077] Compared to measurement methods based on diffractive optical elements in related technologies, diffractive optical elements are manufactured using micro-nano etching processes. The laser beam diffracts after passing through each diffraction unit, and interference occurs at a certain distance, forming a specific light intensity distribution for measurement. This method is characterized by high efficiency and small size. However, due to manufacturing errors or design reasons, diffractive optical elements typically exhibit multiple diffraction orders. This can generate interference light in the optical system, limiting its application range. Furthermore, diffractive optical elements are sensitive to the angle of incident light, requiring high optical path adjustment accuracy and stability. If other components in the optical path, such as mirrors and lenses, lack sufficient precision, it will affect the final result. The Hartmann wavefront detector used in this application, as a non-interference wavefront measurement technique, is less affected by environmental interference (such as vibration and airflow) and can operate stably in relatively complex environments.

[0078] In this way, the wavefront signal can be propagated to the retina under test, and the reflected wavefront signal can be injected into the wavefront detector.

[0079] In some embodiments, the measuring device further includes: a collimating lens group; when the measuring device performs the above step S101 of "sending wavefront signal to the retina to be tested", it may also perform the following steps: collimating the wavefront signal through the collimating lens group and sending the collimated wavefront signal to the retina to be tested.

[0080] In embodiments of this application, the measuring device can collimate the wavefront signal using a collimating lens group and then send the collimated wavefront signal to the retina under test. For example... Figure 2 As shown, the measuring device also includes a collimating lens group 210.

[0081] For example, Figure 2 The provided measuring device includes a wavefront signal source, which, after being collimated by a collimating lens group, enters the beam splitter 29 via a scanning assembly (rotating plane mirror, spherical mirror, and light-transmitting aperture), and then enters the human eye (the retina to be measured) via a relay lens group 27 and a beam splitter 26. When the wavefront signal returns from the human eye, it passes through the beam splitter 26 and the relay lens group 27, and then continues to propagate along its original direction at the beam splitter 29 to the imaging lens group 28, where it is received by a Hartmann wavefront detector (wavefront detector) 22 with a microlens array. During the measurement process, the reflecting mirror (rotating plane mirror) 231 rotates and is incident on different positions of the spherical reflecting mirror (spherical mirror) 233 to scan the entire retinal area; the pupil imaging lens group 25 and the charge-coupled device (CCD) sensor 251 are used to receive images of the subject's pupil in real time, facilitating real-time aiming or corneal curvature measurement. For example, refer to... Figure 2 As shown in Figures 5(a) and (b), the wavefront signal source can incident a wavefront signal onto a plane mirror 231 (plane mirror) that is rotated at a 45° angle around the z-axis, and then onto a spherical mirror (spherical mirror 233). As the plane mirror 231 rotates, the signal source will complete a line scan along the path shown in the top view of the spherical mirror in Figure 5(a). At the same time, the wavefront signal source 21, the collimation system 210, the plane mirror 231, the spherical mirror 233, and the aperture 234 will move back and forth along the x-axis as a whole to achieve scanning of the entire retinal area.

[0082] In some embodiments, when the testing device performs the above-described step S103, "performs image processing on multiple wavefront signal images respectively to obtain corresponding multiple wavefront aberration values", such as Figure 7 As shown, it also includes the following steps S701 to S704:

[0083] Step S701: For each wavefront signal map in the multiple wavefront signal maps, determine the actual centroid of the region where each light spot is located.

[0084] In the embodiments of this application, the measuring device corresponds to a wavefront signal map for each test point (different location) of the retina under test. Each wavefront signal map includes multiple light spots, and the measuring device can determine the actual centroid of the region where each light spot is located. That is, each light spot in each wavefront signal map corresponds to an actual centroid. For example, Figure 8 The image shown is a schematic diagram of a wavefront signal, where the white areas represent light spots.

[0085] Step S702: For each wavefront signal map, determine the theoretical centroid of the region where each of the included light spots is located, and determine the positional deviation between the actual centroid and the theoretical centroid of each of the included light spots.

[0086] In the embodiments of this application, the center point of the region where each light spot is located can be taken as the theoretical centroid. Thus, for each region where a light spot is located, there will be an actual centroid and a theoretical centroid. In this way, the positional deviation between the actual centroid and the theoretical centroid can be determined for each region where a light spot is located. An exemplary formula for determining this is shown in formula (1):

[0087]

[0088] Where, x c Let y be the x-coordinate of the actual centroid. c x is the ordinate of the actual centroid, x0 is the abscissa of the theoretical centroid, y0 is the ordinate of the theoretical centroid, Δx is the positional deviation of the abscissa, and Δy is the positional deviation of the ordinate.

[0089] Step S703: For each wavefront signal image, based on the positional deviation of each included spot, determine the wavefront slope of each included spot, and based on the wavefront slope of each included spot, determine the wavefront aberration of each included spot.

[0090] In the embodiments of this application, for each wavefront signal map, the wavefront slope of each corresponding light spot is obtained according to the positional deviation of each light spot included.

[0091] For example, Figure 9 This diagram illustrates the basis for determining wavefront aberrations. According to the definition of wavefront aberration, aberration is the deviation between the theoretical wavefront and the actual wavefront. Taking the y-axis as an example... Figure 9As shown, R is the optical path length of the actual wavefront, f is the focal length of a single lens in the microlens array, W is the wavefront aberration, Δy is the positional deviation, and P is the detector plane. Since the beam will converge to the center of the region under ideal conditions, the optical path length of the ideal wavefront can be approximated as f. Therefore, the slope of the wavefront on the y-axis component is given by formula (2):

[0092]

[0093] Where f is the focal length of a single lens in the microlens array, W is the wavefront aberration, and Δy is the positional deviation.

[0094] Similarly, the slope of the x-axis component is given by formula (3):

[0095]

[0096] Where f is the focal length of a single lens in the microlens array, W is the wavefront aberration, and Δx is the positional deviation.

[0097] In the embodiments of this application, the measurable device can directly determine the corresponding wavefront aberration based on the wavefront slope of each light spot. An exemplary method for determining the wavefront aberration is shown in formula (4):

[0098]

[0099] In this way, the wavefront phase difference of the region where each light spot is located can be obtained.

[0100] Step S704: For each wavefront signal image, use a preset fitting model to fit the wavefront aberration of each included spot and determine the corresponding wavefront aberration value.

[0101] In the embodiments of this application, for each wavefront signal image, a preset fitting model is used to fit the wavefront aberrations of each included spot to determine the corresponding wavefront aberration value. For example, the preset fitting model can be a Zernike polynomial fitting model. Zernike polynomials, proposed by the Dutch physicist Fritz Zernike, are essentially a set of orthogonal bases defined within the unit circle. The first 5 orders, i.e., the first 21 terms, are commonly used to characterize the aberrations of the human eye.

[0102] The general form of the Zernikal polynomial in polar coordinates is given by formula (5):

[0103]

[0104] in, These are the normalization coefficients; ρ is the radial coefficient; M(mθ) is the azimuth term; ρ ranges from [0,1], representing the radial distance from the aperture center to any point; n is the radial order; m is the azimuth order, and |m| and n should both be odd or even. The expressions for the normalization term are given in formulas (6) and (7):

[0105]

[0106] Where δ takes the value of 1 when m = 0, and takes the value of 0 in other cases;

[0107] The expression for the radial term is shown in formula (8):

[0108]

[0109] Where n is even or odd, It will only contain even / odd terms of ρ.

[0110] The expression for the azimuth angle is given in formula (9):

[0111]

[0112] By fitting the aberrations calculated by formula (4) by adding Zernike polynomials of different terms, the fitted refractive topographic map can be obtained.

[0113] In some embodiments, when the measuring device performs step S701 as described above, such as Figure 10 As shown, the process may include the following steps S1001 and S1002:

[0114] Step S1001: Perform binarization processing on each wavefront signal image to obtain the corresponding processed signal image, and determine the target area including each light spot from the corresponding processed signal image.

[0115] In the embodiments of this application, for each wavefront signal image, the measuring device can use mean filtering to denoise the image, and then perform binarization to obtain the processed signal image. For the processed signal image, a suitable structuring element can be selected to perform a closing operation on the binary image. Closing operations can typically eliminate narrow discontinuities and elongated gaps, eliminate small holes, and fill breaks in the contour lines, thus making the actual centroid obtained based on the processed signal image more accurate. Since the pixel grayscale values ​​of the binary image are only 0 and 1, finding the portion with a pixel value of 1 indicates the target area of ​​the light spot.

[0116] Step S1002: For the target area of ​​each light spot, use the preset ellipse fitting method to determine the corresponding actual centroid based on each pixel point in the corresponding area.

[0117] In the embodiments of this application, for each target area of ​​a light spot, a preset ellipse fitting method is used to determine the corresponding actual centroid based on the position information of each pixel point within the corresponding area.

[0118] Thus, the actual centroid determined based on the blurred light spot is more accurate.

[0119] In some embodiments, when the measuring device performs step S1002 as described above, such as Figure 11 As shown, steps S1101 to S1103 can also be performed:

[0120] Step S1101: Based on the ellipse equation and the least squares method, construct the fitting objective function, solve the fitting objective function, and determine the solution equation.

[0121] In the embodiments of this application, the measuring device can construct a fitting objective function based on the ellipse equation and the least squares method. For example, the ellipse equation is shown in formula (10):

[0122] x 2 +Axy+By 2 +Cx+Dy+E=0(10);

[0123] Where A, B, C, D, and E are elliptic coefficients.

[0124] For each pixel in the target region corresponding to a light spot, the target function obtained by fitting using the least squares method is shown in formula (11):

[0125]

[0126] To minimize the value of this function, its partial derivatives must be zero, as shown in formula (12):

[0127]

[0128] Thus, we can obtain formula (13):

[0129]

[0130] Simplified as formula (14):

[0131]

[0132] Formula (15) can be obtained:

[0133]

[0134] in, Let M1 be the inverse matrix.

[0135] Step S1102: Substitute the position of each pixel within the target area of ​​each light spot into the solution equation to obtain the corresponding elliptic coefficients.

[0136] In the embodiments of this application, for each light spot, the position of each pixel in the corresponding target area is substituted into formula (13) to obtain the corresponding elliptic coefficients: A, B, C, D, E.

[0137] Step S1103: For each target area of ​​the light spot, determine the corresponding actual centroid based on the corresponding elliptic coefficient.

[0138] In the embodiments of this application, for each target area of ​​a light spot, the corresponding actual centroid is determined based on the corresponding elliptic coefficient. An exemplary method for determining the actual centroid is given in formula (16):

[0139]

[0140] Where x is the x in formula (1) above. c y is the y in formula (1) above. c .

[0141] In this way, the actual centroid of the region where each light spot is located can be determined. Since the centroid is determined based on the target region containing the blurred light spots within the region, the accuracy is higher than that determined based on the actual centroid of the entire region where the light spot is located.

[0142] For example, Figure 12 An exemplary flowchart for generating refractive topographic maps is provided, such as... Figure 12 As shown, the exemplary implementation process for generating a refractive topographic map includes the following steps S1201 to S1208:

[0143] Step S1201: Calculate the actual centroid of the light spot in each rectangular region.

[0144] Here, the testing device can acquire an unprocessed wavefront signal image and then calculate the actual centroid of the rectangular region where each spot is located. An exemplary calculation method is described in steps S1001 and S1002, and steps S1102 to S1103 above.

[0145] Step S1202: Calculate the positional deviation between the actual spot centroid and the theoretical spot centroid.

[0146] Here, the testing device calculates the positional deviation between the actual and theoretical centroids of each spot in its respective region. For an example calculation method, please refer to step S702 above.

[0147] Step S1203: Derive the wavefront slope using geometric optics.

[0148] Here, the testing device derives the wavefront slope through geometric optics, and the exemplary derivation method is described in step S703 above.

[0149] Step S1204: Calculate the wavefront aberration of each independent rectangular region using positional deviation.

[0150] Here, the testing device calculates the wavefront aberration of each independent rectangular region by means of positional deviation. For an example of calculating the wavefront aberration, see step S703 above.

[0151] Step S1205: Zernike coefficient fitting.

[0152] Here, the testing device uses Zernike coefficients to fit the wavefront aberration values ​​of each spot, and the wavefront aberration values ​​corresponding to the unprocessed wavefront signal map in step S1201 above can be obtained here; see step S704 above for an exemplary fitting method.

[0153] Step S1206: Is the calculation complete?

[0154] Here, the testing device will determine whether there are still unprocessed wavefront signal maps. If there are still unfinished wavefront signal maps, step S1207 will be executed. If all wavefront signal maps are completed, that is, the corresponding wavefront aberration values ​​are obtained, it means that the calculation is complete.

[0155] Step S1207: Read the next signal diagram.

[0156] Here, the testing device will continue to acquire the next unprocessed wavefront signal image, and then execute the above steps S1201 and S1205.

[0157] Step S1208: Generate a refractive topographic map.

[0158] Here, after obtaining the wavefront pixel differences corresponding to all wavefront signal maps, the testing device can generate a refractive topographic map based on the wavefront pixel differences corresponding to all wavefront signal maps.

[0159] For example, the method of generating refractive topography can also include the following steps: Step S1, a wavefront signal source emits a light signal, which enters the pupil of the subject (the retina to be tested), forming a wavefront signal on the retina; Step S2, after being reflected by the retina, the wavefront signal exits from the human eye and returns to the Hartmann microlens array, and then enters the wavefront aberration detector; Step S3, the wavefront aberration detector receives the distorted point array distributed discrete light spots, and obtains the corresponding image (wavefront signal map); Step S4, during the measurement process, the scanning mechanism (scanning component) is used to adjust the position of the measurement light incident on the retina to achieve a signal scan of the entire retina; Step S5, after obtaining all wavefront signal maps, the Hartmann wavefront analysis method is applied to process all signal maps to obtain wavefront aberrations; the measured values ​​of each aberration are calculated using the Zernike model; Step S6, based on the aberration calculation results and the corresponding values ​​of the spatial position of the retina, the refractive topography distribution of the retina is generated.

[0160] This application provides a method for measuring retinal refractive topography. The method includes: sending a wavefront signal to the retina under test via a wavefront signal light source, and moving a scanning component and / or a portion thereof to adjust the position of the wavefront signal incident on the retina; receiving wavefront signals reflected from different positions on the retina under test via a wavefront detector, and forming a corresponding wavefront signal map for each position, resulting in multiple wavefront signal maps corresponding to multiple positions; and performing image processing on the multiple wavefront signal maps using a topography generation module to obtain multiple corresponding wavefront aberration values, and mapping the multiple wavefront aberration values ​​to corresponding positions among the multiple positions to generate a retinal refractive topography. The retinal refractive topography measurement method provided in this application, by moving the scanning component to scan different positions on the retina, simplifies the complexity of optical system design, improves measurement efficiency, and reduces the risk of measurement errors.

[0161] This application provides a retinal refractive topography measuring device 20, such as... Figure 13 As shown, it includes: a wavefront signal source 21, a wavefront detector 22, a scanning component 2323, and a topographic map generation module 2424; the scanning component 23 is located in the optical path between the wavefront signal source 21 and the wavefront detector 22.

[0162] Wavefront signal source 21 is used to send wavefront signals to the retina under test;

[0163] The moving module 211211 is used to move the scanning assembly 23 and / or some components in the scanning assembly 23 to adjust the position of the wavefront signal incident on the retina to be tested.

[0164] Wavefront detector 22 is used to receive wavefront signals reflected from different positions of the retina under test, and to form a corresponding wavefront signal map for each position, thereby obtaining multiple wavefront signal maps corresponding to multiple positions.

[0165] The topographic map generation module 24 is used to perform image processing on multiple wavefront signal maps to obtain multiple corresponding wavefront aberration values, and to map the multiple wavefront aberration values ​​to the corresponding positions in multiple locations to generate a retinal refractive topographic map.

[0166] In one embodiment of this application, the scanning component 23 includes a plane mirror 231 and a scanning bracket 232; the plane mirror 231 is mounted on the scanning bracket 232; the moving module 211 is also used to control the plane mirror 231 to rotate multiple times around the central axis of the plane mirror 231 within a preset angle, and to project wavefront signals into the retina to be tested through the plane mirror 231; wherein, the central axis is perpendicular to the direction in which the wavefront signal light source 21 transmits the wavefront signal; after each rotation of the plane mirror 231, the scanning bracket 232 is controlled to move in a direction perpendicular to the central axis within a preset range; wherein, the direction of movement of the scanning bracket 232 is opposite when the plane mirror 231 rotates twice consecutively.

[0167] In one embodiment of this application, the scanning component 23 further includes a spherical mirror 233; the spherical mirror 233 is mounted on the scanning bracket 232; the center of the spherical mirror 233 is located on the central axis; and a plane mirror 231 is used to reflect the wavefront signal to the spherical mirror 233, and to use the spherical mirror 233 to project the reflected wavefront signal into the retina to be tested.

[0168] In one embodiment of this application, the scanning bracket 232 is provided with a light-transmitting aperture 234; a spherical mirror 233 is used to transmit the reflected wavefront signal into the retina to be tested through the light-transmitting aperture 234.

[0169] In one embodiment of this application, the testing device further includes: a pupil imaging group 25, a beam splitter 26, a relay lens group 27, and an imaging lens group 28; the beam splitter 26 is used to transmit wavefront signals reflected from different positions of the retina to be tested into the pupil imaging group 25 and the relay lens group 27 respectively; the pupil imaging group 25 is used for aiming or measuring corneal curvature based on the wavefront signals reflected from different positions; the relay lens group 27 is used to transmit the wavefront signal propagated by the beam splitter 26 through the imaging lens group 28 into the wavefront detector 22.

[0170] In one embodiment of this application, the measuring device further includes: a collimating lens group 210; the collimating lens group 210 is used to collimate the wavefront signal and send the collimated wavefront signal to the retina to be measured.

[0171] In one embodiment of this application, the topographic map generation module 24 is further configured to: determine the actual centroid of the region where each of the included light spots is located for each of the multiple wavefront signal maps; determine the theoretical centroid of the region where each of the included light spots is located for each wavefront signal map, and determine the positional deviation between the actual centroid and the theoretical centroid of each of the included light spots; determine the wavefront slope of each of the included light spots for each wavefront signal map based on the positional deviation of each of the included light spots, and determine the wavefront aberration of each of the included light spots based on the wavefront slope of each of the included light spots; and fit the wavefront aberration of each of the included light spots for each wavefront signal map using a preset fitting model to determine the corresponding wavefront aberration value.

[0172] In one embodiment of this application, the topographic map generation module 24 is further configured to perform binarization processing on each wavefront signal map to obtain the corresponding processed signal map, and determine the corresponding target area including each light spot from the corresponding processed signal map; for each target area of ​​the light spot, the corresponding actual centroid is determined based on each pixel point in the corresponding area using a preset ellipse fitting method.

[0173] In one embodiment of this application, the topographic map generation module 24 is further configured to construct a fitting objective function based on the ellipse equation and the least squares method, and solve the fitting objective function to determine the solution equation; substitute the position of each pixel point in the target area of ​​each spot into the solution equation to obtain the corresponding ellipse coefficient; and determine the corresponding actual centroid for the target area of ​​each spot based on the corresponding ellipse coefficient.

[0174] This application provides a device for measuring retinal refractive topography, including a wavefront signal source, a wavefront detector, a scanning component, and a topography generation module. The scanning component is located in the optical path between the wavefront signal source and the wavefront detector. The wavefront signal source is used to send a wavefront signal to the retina under test. A moving module is used to move the scanning component and / or some components of the scanning component to adjust the position where the wavefront signal is incident on the retina under test. The wavefront detector is used to receive wavefront signals reflected from different positions on the retina under test and form a corresponding wavefront signal map for each position, resulting in multiple wavefront signal maps corresponding to multiple positions. The topography generation module is used to perform image processing on the multiple wavefront signal maps to obtain multiple corresponding wavefront aberration values, and map the multiple wavefront aberration values ​​to corresponding positions in the multiple positions to generate a retinal refractive topography. The retinal refractive topography measurement device provided in this application, by moving the scanning component to scan different positions on the retina, simplifies the complexity of optical system design, improves measurement efficiency, and reduces the risk of measurement errors.

[0175] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for measuring retinal refractive topography, characterized in that, A measuring device for retinal refractive topography, the measuring device comprising a wavefront signal source, a wavefront detector, a scanning assembly, and a topography generation module; the scanning assembly is located in the optical path between the wavefront signal source and the wavefront detector; the scanning assembly includes a plane mirror, a scanning bracket, and a spherical mirror; the plane mirror and the spherical mirror are mounted on the scanning bracket; the center of the spherical mirror is located on the central axis of the plane mirror; the scanning bracket has a light-transmitting aperture; the method includes: A wavefront signal is sent to the retina under test via the wavefront signal light source, and the plane mirror is controlled to rotate multiple times within a preset angle around its central axis. The wavefront signal is reflected to the spherical mirror via the plane mirror. The reflected wavefront signal is then transmitted to the retina under test through the light-transmitting aperture via the spherical mirror. The central axis is perpendicular to the direction in which the wavefront signal is sent by the wavefront signal light source. After each rotation of the plane mirror, the scanning support is controlled to move in a direction perpendicular to the central axis within a preset range. The scanning support moves in opposite directions during two consecutive rotations of the plane mirror. Alternatively, the plane mirror can be set to move while the scanning component remains stationary, and the plane mirror can move in at least two directions; Alternatively, the plane mirror can be set to remain stationary, while the scanning component moves along a direction perpendicular to the central axis and a direction parallel to the central axis. The wavefront detector receives wavefront signals reflected from different positions of the retina under test, and forms a corresponding wavefront signal map for each position, thus obtaining multiple wavefront signal maps corresponding to multiple positions. The topographic map generation module performs image processing on the multiple wavefront signal maps to obtain multiple corresponding wavefront aberration values, and maps the multiple wavefront aberration values ​​to the corresponding positions among the multiple locations to generate the retinal refractive topographic map.

2. The method for measuring retinal refractive topography according to claim 1, characterized in that, The measuring device further includes: a pupil imaging group, a beam splitter, a relay lens group, and an imaging lens group; the step of receiving wavefront signals reflected from different positions of the retina under test through the wavefront detector includes: The wavefront signals reflected from different positions of the retina under test are directed into the pupil imaging group and the relay lens group via the beam splitter; the pupil imaging group is used for aiming or corneal curvature measurement based on the wavefront signals reflected from different positions. The wavefront signal propagated by the beam splitter is transmitted through the relay mirror group and then into the wavefront detector via the imaging mirror group.

3. The method for measuring retinal refractive topography according to claim 1, characterized in that, The measuring device further includes: a collimating lens group; the step of sending wavefront signals to the retina under test includes: The wavefront signal is collimated using the collimating lens group, and the collimated wavefront signal is then sent to the retina under test.

4. The method for measuring retinal refractive topography according to any one of claims 1 to 3, characterized in that, The step of performing image processing on the plurality of wavefront signal images to obtain corresponding plurality of wavefront aberration values ​​includes: For each of the multiple wavefront signal maps, determine the actual centroid of the region where each light spot is located; For each wavefront signal image, the theoretical centroid of the region containing each included spot is determined, and the positional deviation between the actual centroid and the theoretical centroid of each included spot is determined. For each wavefront signal image, the wavefront slope of each included light spot is determined based on the positional deviation of each included light spot, and the wavefront aberration of each included light spot is determined based on the wavefront slope of each included light spot. For each wavefront signal image, a preset fitting model is used to fit the wavefront aberration of each included spot to determine the corresponding wavefront aberration value.

5. The method for measuring retinal refractive topography according to claim 1, characterized in that, For each of the plurality of wavefront signal maps, determining the actual centroid of the corresponding region containing each light spot includes: Each wavefront signal image is binarized to obtain a corresponding processed signal image, and the target region including each light spot is determined from the corresponding processed signal image. For each target area of ​​the light spot, the corresponding actual centroid is determined based on each pixel within the corresponding area using a preset ellipse fitting method.

6. The method for measuring retinal refractive topography according to claim 5, characterized in that, For each target area of ​​the light spot, a preset ellipse fitting method is used to determine the corresponding actual centroid based on each pixel within the corresponding area, including: Based on the elliptic equation and the least squares method, a fitting objective function is constructed, and the fitting objective function is solved to determine the solution equation; Substitute the position of each pixel within the target area of ​​each light spot into the solution equation to obtain the corresponding elliptic coefficients; For each target area of ​​the light spot, the corresponding actual centroid is determined based on the corresponding elliptic coefficient.

7. A measuring device for retinal refractive topography, characterized in that, The system includes a wavefront signal source, a wavefront detector, a scanning assembly, and a topographic map generation module. The scanning assembly is located in the optical path between the wavefront signal source and the wavefront detector. The scanning assembly includes a plane mirror, a scanning bracket, and a spherical mirror. The plane mirror and the spherical mirror are mounted on the scanning bracket. The center of the spherical mirror is located on the central axis of the plane mirror. The scanning bracket has a light-transmitting aperture. The wavefront signal light source is used to send wavefront signals to the retina under test; A moving module controls the plane mirror to rotate multiple times within a preset angle around its central axis, and uses the plane mirror to reflect the wavefront signal to the spherical mirror; the spherical mirror then directs the reflected wavefront signal through the light-transmitting aperture into the retina to be tested; wherein the central axis is perpendicular to the direction in which the wavefront signal is emitted by the wavefront signal source; after each rotation of the plane mirror, the scanning support is controlled to move along a direction perpendicular to the central axis within a preset range; wherein the scanning support moves in opposite directions during two consecutive rotations of the plane mirror; or, the plane mirror moves while the scanning component remains stationary, and the plane mirror moves in at least two directions; or, the plane mirror does not move while the scanning component moves along a direction perpendicular to the central axis and a direction parallel to the central axis. The wavefront detector is used to receive wavefront signals reflected from different positions of the retina under test, and to form a corresponding wavefront signal map for each position, thereby obtaining multiple wavefront signal maps corresponding to multiple positions. The topographic map generation module is used to perform image processing on the multiple wavefront signal maps respectively to obtain multiple corresponding wavefront aberration values, and to map the multiple wavefront aberration values ​​to the corresponding positions among the multiple locations to generate the retinal refractive topographic map.

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