Corneal curvature measuring system and corneal curvature measuring device

Abstract

The invention provides a corneal curvature measurement system and a corneal curvature measurement device, relates to the technical field of eye imaging and measurement, can reduce the debugging difficulty of a corneal curvature measurement light source, and does not limit the imaging view of other light paths in the same system or device. The corneal curvature measuring system comprises an eyepiece set, a light source module, a camera module and a diaphragm, the light source module, the camera module and the diaphragm are located on the inner side of the eyepiece set, the light source module comprises a point light source array, the point light source array emits light or forms an image on a focal plane on the inner side of the eyepiece set, and multiple collimated light beams are emitted through the eyepiece set and enter a measured eyeball. A plurality of collimated light beams fall on the circumference of the cornea on the same latitude, a cornea light spot virtual image is formed after the collimated light beams are reflected by the cornea, then a real image is formed on the detection surface of the camera through the eyepiece group and the camera module, and the cornea curvature is measured according to the position information of the cornea light spot in the real image.

Description

Technical Field

[0001] The present application relates to the field of eye imaging and measurement technology, and in particular, to a corneal curvature measurement system and a corneal curvature measurement device. Background Art

[0002] In ophthalmic cataract surgery, choosing the right intraocular lens (IOL) is crucial. The mainstream intraocular lenses are selected based on the user's axial length and corneal curvature as the model and type. Clinically, the existing technology usually uses a biometer to measure the basic parameters of the eyeball and then perform relevant calculations. Commonly used calculation formulas include: Holladay 1, Holladay 2, SRK / T, Hoffer Q, Haigis, Barrett Universal II, Olsen, Hill-RBF, T2, Kane and EVO formulas. The input parameters of these formulas all include corneal curvature (SimK), and accurate corneal curvature must be obtained through a biometer to ensure high calculation accuracy.

[0003] When measuring the basic parameters of the eyeball using a biometer, for the measurement of corneal curvature, Figure 1 The figure shows a schematic diagram of the optical path of the currently common method of measuring corneal curvature by using a biometer to project light points on the cornea.

[0004] The measurement system is placed in front of the eyeball to be measured, and the pupil of the eye is located near the focus of the eyepiece 1-2. A collimated light source array is installed next to the eyepiece 1-2. Each lighting unit of the light source array is usually an LED 1-1 plus a collimating lens 1-11. After being collimated, the light emitted by multiple LEDs 1-1 is directed to a circle at the same latitude on the cornea, and the extended lines of the collimated light converge at the same point on the posterior optical axis of the cornea. The collimated light is reflected by the cornea to form a virtual image, which is the virtual image AA of the corneal light reflection point.

[0005] The specific calculation includes: the image height of the virtual image AA of the corneal reflection point formed on the cornea is h,

[0006] h=f·tanθ(1)

[0007] Where f is the effective focal length of the front surface of the cornea as a convex reflector, and θ is the angle between the collimated light beam and the optical axis. Figure 1 The angle between the collimated light from LED 1-1 and the optical axis is defined as negative. Under the paraxial light approximation,

[0008]

[0009] Wherein, ρ is the radius of curvature of the central area of ​​the cornea, and ρ is positive.

[0010] The collimation of the light beam ensures that the height of the virtual image is independent of the working distance (the working distance is defined as the distance from the vertex of the surface adjacent to the eyepiece 1-2 and the human eye to the vertex of the cornea), which helps to overcome the measurement error caused by the uncertainty of the working distance during measurement.

[0011] The light beam reflected by the cornea passes through the eyepiece 1-2 in sequence, the aperture 1-3 arranged on the focal plane on the inner side of the eyepiece 1-2 (to avoid ambiguity, the "inner side" in this application document refers to the side of the eyepiece away from the eye, and the "outer side" refers to the side of the eyepiece close to the eye), and then passes through the camera lens group 1-4 and enters the camera detection surface 1-5 to form a real image.

[0012] Under the paraxial light approximation, the image height of the real image is:

[0013]

[0014] Among them, f 1-2 is the effective focal length of eyepiece 1-2, f 1-4 is the effective focal length of camera lens group 1-4.

[0015] It can be seen that the image height of the real image formed on the camera detection surface 1-5 is proportional to the corneal curvature radius.

[0016] Although the corneal curvature can be measured by using a single LED 1-1 as a light source in the system, considering that the eccentricity of a single LED 1-1 will also affect the accuracy of the measurement result, the light source is usually an LED 1-1 array distributed on a circle centered on the main optical axis. The light source arranged in this way can effectively eliminate the adverse effect of the eccentricity of the cornea on the measured eyeball on the measurement result. The radius R of the circle is obtained by fitting the position of the real image formed by the array of LEDs 1-1 on the camera detection surface 1-5, and the corneal curvature radius ρ is calculated according to formula (4).

[0017]

[0018] Before using a keratometer system to measure corneal curvature, a spherical surface with a known curvature radius can be measured to correct the optical system, and then the eyeball or other spherical object with an unknown radius can be measured.

[0019] Since the LEDs 1-1 in the light source array are arranged in a circular array around the eyepiece 1-2, the angle between the collimated light beam and the optical axis of the eyepiece 1-2 is usually around 20°, which limits the size of the eyepiece 1-2 and the field of view of other optical paths in the system (such as OCT optical coherence tomography). Moreover, the collimated light beams emitted by the LEDs 1-1 arranged in a circular pattern on the same circumference of the light source array are all directed toward the cornea at a specific angle, and the light spot must fall on a specific position on the circle of the same latitude on the cornea (or the standard sphere used for calibration), and the extension lines of the collimated light beams emitted by the LEDs 1-1 arranged in a circular pattern on the same circumference must also converge on a point on the rear optical axis of the cornea (or the standard sphere used for calibration). This also brings huge challenges to the installation and debugging of the measurement system, especially the array light source. Summary of the invention

[0020] The present application provides a corneal curvature measurement system and a corneal curvature measurement device, which can reduce the difficulty of debugging a light source and do not limit the imaging field of view of other light paths in the same system or device.

[0021] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0022] In one aspect of an embodiment of the present application, a corneal curvature measurement system is provided, comprising an eyepiece group and a light source module, a camera module and an aperture located inside the eyepiece group, the light source module comprising a point light source array, the point light source array emits light or forms an image on a focal plane inside the eyepiece group, and is emitted through the eyepiece group as a plurality of collimated light beams and incident on an eyeball to be measured outside the eyepiece group, the plurality of collimated light beams respectively fall on circles at the same latitude of the cornea and are reflected by the cornea to form virtual images of corneal light reflection points, the camera module comprising a camera and a camera lens group, the plurality of collimated light beams are reflected by the cornea and sequentially pass through the eyepiece group, the aperture and the camera lens group to form real images on a detection surface of the camera, and the corneal curvature is calculated based on the position information of the corneal light reflection points in the real image.

[0023] Another aspect of an embodiment of the present application provides a corneal curvature measurement device, comprising any one of the aforementioned corneal curvature measurement systems.

[0024] The beneficial effects of the embodiments of the present application include:

[0025] The embodiment of the present application provides a corneal curvature measurement system, in which an array of point light sources emits light or forms an image on the focal plane inside the eyepiece group. The light beams are emitted through the eyepiece group as multiple collimated light beams and enter the eyeball to be measured outside the eyepiece group. The array of point light sources is located on the inside of the eyepiece group, so that the structural size of the eyepiece group is not restricted. The eyepiece group can be adaptively set according to the space of the device structure and the imaging field of view required by other branch light paths in the system. For example, when an OCT light path needs to be added to a biometric instrument to realize visual axial length measurement, the eyepiece group can cooperate with the OCT light path to achieve a larger scanning field of view. In addition, the array of point light sources used to form corneal reflection points is located in the same plane, facing the same direction, and uses the common eyepiece group as a collimating lens. There is no need to set a collimating lens for each point light source separately. All point light sources can be installed on the same circuit board, which greatly facilitates manufacturing, installation and adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of the optical path of a corneal curvature measurement system in the prior art;

[0028] Figure 2 One of the optical path schematic diagrams of a corneal curvature measurement system provided in an embodiment of the present application;

[0029] Figure 3 A second optical path schematic diagram of a corneal curvature measurement system provided in an embodiment of the present application;

[0030] Figure 4 A third optical path schematic diagram of a corneal curvature measurement system provided in an embodiment of the present application;

[0031] Figure 5 One of the schematic diagrams of the arrangement of a point light source array in a corneal curvature measurement system provided in an embodiment of the present application;

[0032] Figure 6 The second schematic diagram of the arrangement of a point light source array in a corneal curvature measurement system provided in an embodiment of the present application;

[0033] Figure 7 The third schematic diagram of the arrangement of a point light source array in a corneal curvature measurement system provided in an embodiment of the present application;

[0034] Figure 8A fourth schematic diagram of the arrangement of a point light source array in a corneal curvature measurement system provided in an embodiment of the present application;

[0035] Fig. 9 A fifth schematic diagram of the arrangement of a point light source array in a corneal curvature measurement system provided in an embodiment of the present application;

[0036] Fig.10 The sixth schematic diagram of the arrangement of a point light source array in a corneal curvature measurement system provided in an embodiment of the present application;

[0037] Fig.11 The seventh schematic diagram of the arrangement of a point light source array in a corneal curvature measurement system provided in an embodiment of the present application;

[0038] Fig.12 The eighth schematic diagram of the arrangement of a point light source array in a corneal curvature measurement system provided in an embodiment of the present application;

[0039] Fig.13 A real image received by a detection surface of a camera in a corneal curvature measurement system provided in an embodiment of the present application;

[0040] Fig.14 A relationship diagram of the circular radius of a real image received by a camera detection surface according to multiple measurements and the curvature radius of a spherical surface with known curvature used for calibration in a corneal curvature measurement system provided in an embodiment of the present application.

[0041] Icon: 1-1-LED; 1-11-collimating lens; 1-2-eyepiece; 1-3-aperture; 1-4-camera lens group; 1-5-camera detection surface; AA-virtual image of the corneal light reflection point; BB-real image of the corneal light reflection point; CC-real image of the point light source array; 100-eyepiece group; 200-OCT optical path; 210-dichroic mirror; 300-light source module; 310-point light source array; 311-fixation lamp; 320-beam splitter; 340-light source aperture; 400-camera module; 410-camera; 420-camera lens group; 421-first camera lens group; 422-second camera lens group; 500-aperture; 510-camera lens group aperture; 600-imaging lens group; 610-first light source lens group; 620-second light source lens group. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. It should be noted that, in the absence of conflict, the various features in the embodiments of the present application can be combined with each other, and the combined embodiments are still within the scope of protection of the present application.

[0043] In the description of the present application, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0044] When measuring the basic parameters of the eyeball using a biometer, for the measurement of corneal curvature, Figure 1 This is a schematic diagram of the optical path of the current method of measuring corneal curvature using a biometer by projecting light points on the cornea. Figure 1 As can be seen in the figure, since the LED 1-1 in the light source array is arranged around the eyepiece 1-2 and the angle between the light beam emitted by the LED 1-1 and the optical axis of the eyepiece 1-2 needs to be controlled at about 20°, the size of the eyepiece 1-2 is strictly limited to a smaller size. When the biometer also includes an OCT optical path for visual axial length measurement, the size of the eyepiece 1-2 limits the scanning field of the OCT optical path, making it impossible to perform large-scale scanning imaging.

[0045] In order to solve the above problems, the present application provides a corneal curvature measurement system. Figure 2 As shown, the corneal curvature measurement system of the embodiment of the present application includes an eyepiece group 100 and a light source module 300, a camera module 400 and an aperture 500 located inside the eyepiece group 100. The light source module 300 includes a point light source array 310. The point light source array 310 emits light or forms an image on the focal plane inside the eyepiece group 100. The light is emitted through the eyepiece group 100 as a plurality of collimated light beams and enters the measured eyeball outside the eyepiece group 100. The plurality of collimated light beams fall on the circumference of the cornea at the same latitude, and their extended lines converge at a point on the posterior optical axis of the cornea. The collimated light beam is reflected by the cornea to form a virtual image AA of the corneal light reflection point ( Figure 2 In order to avoid the diagram being too crowded, only one of the light points in the virtual image formed by the multiple collimated light beams falling on the circumference of the cornea at the same latitude is shown). The camera module 400 includes a camera 410 and a camera lens group 420. The multiple collimated light beams are reflected by the cornea and sequentially pass through the eyepiece group 100, the diaphragm 500 and the camera lens group 420 to form a real image on the detection surface of the camera 410. The corneal curvature can be measured and obtained according to the position information of the corneal light point in the real image.

[0046] For examples, please refer to Figure 2 As shown, the corneal curvature measurement system of the embodiment of the present application is placed in front of the eyeball to be measured, and the pupil of the eyeball is located near the focus outside the eyepiece assembly 100.

[0047] like Figure 2As shown in the figure, the point light source array 310 is arranged on the inner focal plane of the eyepiece group 100 and emits light at the focal plane. Alternatively, the point light source array 310 can also be arranged at other external positions according to the optical path design, and the light beams emitted by the point light source array 310 can be projected on the inner focal plane of the eyepiece group 100 to form a real image through additional optical elements.

[0048] like Figure 2 As shown, the corneal curvature measurement system of the embodiment of the present application also includes an OCT optical path 200 for measuring relevant parameters such as the axial length of the eyeball being measured. For example, the OCT optical path 200 is added to the corneal curvature measurement system of the embodiment of the present application, and the OCT optical path 200 is merged into the main optical path through the dichroic mirror 210 to be incident on the eyeball being measured and perform signal acquisition and measurement to obtain fundus information such as the axial length.

[0049] The light beam reflected by the cornea sequentially passes through the eyepiece assembly 100, the aperture 500 set on the inner focal plane of the eyepiece assembly 100, and enters the camera lens assembly 420, and finally forms a real image on the detection surface of the camera 410. The image height of the real image is:

[0050]

[0051] Among them, f 100 is the effective focal length of the eyepiece set 100, f 420 is the effective focal length of the camera lens assembly 420, h is the image height of the virtual image AA of the corneal reflection point, and θ is the angle between the collimated light beam and the optical axis.

[0052] It can be seen that the image height of the real image formed on the detection surface of the camera 410 is proportional to the corneal curvature radius.

[0053] Although the corneal curvature can be measured by a single off-axis light source in the system, considering that the eccentricity of a single off-axis light source will also affect the accuracy of the measurement result, the light source module 300 in the corneal curvature measurement system of the embodiment of the present application usually uses a point light source array 310 distributed on a circle centered on the main optical axis to emit light. The point light source array 310 arranged in this way can effectively eliminate the adverse effect of the eccentricity of the cornea on the measured eyeball on the measurement result. The radius R of the circle is obtained by fitting the positions of the real images formed by the multiple point light sources of the point light source array 310 on the detection surface of the camera 410, and the corneal curvature radius ρ is calculated according to formula (6).

[0054]

[0055] Before using the corneal curvature measurement system of the embodiment of the present application to measure corneal curvature, a spherical surface with a known curvature radius can be measured to correct the optical system, and then the eyeball or other spherical object with an unknown radius can be measured.

[0056] It should be noted that, as mentioned above, the corneal curvature measurement system of the embodiment of the present application may also include an OCT optical path 200 for measuring relevant parameters such as the axial length of the eyeball being measured. Figure 2 FIG. 2 shows a specific embodiment in which the OCT optical path 200 is connected to the main optical path inside the eyepiece assembly 100 through a dichroic mirror 210. In addition, in some cases, the OCT optical path 200 can also be arranged outside the eyepiece assembly 100. Figure 2 As a schematic diagram of one specific embodiment, the example is not intended to limit the features of the solution of the present application.

[0057] In addition, it should be noted that in the embodiments of the present application, the optical elements referred to as lens groups, such as the eyepiece group 100, are not strictly limited to being composed of multiple optical lenses. Those skilled in the art can design the eyepiece group 100 as a single optical lens or a combination of two or more optical lenses according to system requirements based on the specific parameters of the optical path system, which are all within the protection scope of the present application. The same is true for other lens groups involved in the present application, which will not be described one by one below.

[0058] The embodiment of the present application provides a corneal curvature measurement system, in which a point light source array 310 emits light or forms an image on the focal plane inside the eyepiece group 100, and the light beam is emitted through the eyepiece group 100 as a plurality of collimated light beams and enters the eyeball to be measured outside the eyepiece group 100. The point light source array 310 is located inside the eyepiece group 100, so that the structural size of the eyepiece group 100 is not restricted. The eyepiece group 100 can be adaptively set according to the space of the device structure and the imaging field required by other branch light paths in the system. For example, when the OCT light path 200 needs to be added to the biometric instrument to realize the visual measurement of the axial length of the eye, the eyepiece group 100 can cooperate with the OCT light path 200 to realize a larger scanning field of view. In addition, the point light source array 310 used to form the corneal reflection point is located in the same plane, facing the same direction, and the eyepiece group 100 is used as a collimating lens. There is no need to set a collimating lens for each point light source separately, and all point light sources can be installed on the same circuit board, which brings great convenience to manufacturing, installation and adjustment.

[0059] In a possible implementation, Figure 2 As shown, the aperture 500 is located at the focal plane inside the eyepiece assembly 100 , and the optical system composed of the eyepiece assembly 100 and the camera lens assembly 420 is telecentric imaging on one side of the eyepiece assembly 100 .

[0060] Still refer to Figure 2The aperture 500 is arranged on the inner side of the eyepiece group 100 in the corneal curvature measurement system of the embodiment of the present application and is located at the focal plane of the eyepiece group 100. The collimation of the projection light path ensures that the position and image height of the virtual image AA of the corneal light reflection point formed on the cornea are insensitive to the working distance. The aperture 500 located at the focal plane on the inner side of the eyepiece group 100 ensures that the image from the virtual image AA of the corneal light reflection point to the detection surface of the camera 410 is telecentric imaging. Therefore, the entire imaging process from the point light source array 310 to the reflection of the virtual image AA of the corneal light reflection point to the detection surface of the camera 410 is insensitive to the working distance, thereby ensuring the measurement accuracy of the corneal curvature.

[0061] The aperture 500 includes a physical aperture, which is disposed on the focal plane inside the eyepiece assembly 100. The light beam is directly constrained by the physical aperture at the focal plane of the eyepiece assembly 100 in the optical path from being reflected by the cornea to the camera 410.

[0062] Or, in some other embodiments (see Figure 3 ), the diaphragm 500 can also be a virtual diaphragm, and a conjugate image is formed on the focal plane inside the eyepiece assembly 100 by the camera lens assembly diaphragm 510 arranged in the optical path, and the conjugate image is used as a virtual diaphragm. That is, the camera lens assembly diaphragm 510 used to form the virtual diaphragm can be arranged at other positions in the optical path, as long as the conjugate image that meets the requirements of preset parameters (such as diaphragm aperture) can be made to fall on the focal plane inside the eyepiece assembly 100 through appropriate lens assembly design, the virtual diaphragm can also assume the role or function of the diaphragm 500, thereby not causing physical constraints on the space behind the eyepiece assembly 100, and facilitating the insertion of other measurement optical paths, such as the OCT optical path 200 for measuring relevant parameters such as the axial length of the eyeball to be measured.

[0063] In a possible implementation, Figure 3 As shown, the light source module 300 includes a point light source array 310, a beam splitter 320 disposed on the light-emitting side of the point light source array 310, a first light source lens group 610 and a second light source lens group 620 are further disposed between the point light source array 310 and the beam splitter 320, and a light source aperture 340 located between the first light source lens group 610 and the second light source lens group 620. The light beam emitted by the point light source array 310 passes through the first light source lens group 610, is constrained by the light source aperture 340, passes through the second light source lens group 620, and is merged into the main light path through the beam splitter 320, and forms a point light source array real image CC at the focal plane inside the eyepiece group 100. The light source aperture 340 is located on the focal plane of the second light source lens group 620 close to the first light source lens group 610, so that the point light source array 310 is telecentrically imaged on the focal plane inside the eyepiece group 100. The real image CC of the point light source array is collimated by the eyepiece assembly 100 and falls on the circumference of the cornea at the same latitude, and is reflected by the cornea to form a virtual image AA of the corneal light reflection point.

[0064] An imaging lens group 600 is also provided between the beam splitter 320 and the camera lens group 420. The virtual image AA of the corneal light reflection point passes through the eyepiece group 100, the aperture 500 (virtual aperture), the beam splitter 320 and the imaging lens group 600 in sequence to form a real image BB of the corneal light reflection point, and then passes through the second camera lens group 422 of the camera lens group 420, the camera lens group aperture 510, and the first camera lens group 421 in sequence to form a real image on the detection surface of the camera 410. The camera lens group aperture 510 is conjugate imaged by the second camera lens group 422 in the camera lens group 420 and the imaging lens group 600 near the back focal plane of the eyepiece group 100 to form a virtual aperture (aperture 500), thereby ensuring that the imaging system is telecentrically imaged outside the eyepiece group 100 without affecting the space inside the eyepiece group 100, allowing the system to use a short focal length eyepiece in conjunction with other imaging optical paths such as the OCT optical path 200 to achieve a large range of fundus scanning, and allowing other imaging optical paths such as the OCT optical path 200 to move back and forth to accommodate eyes with different refractive powers.

[0065] The image height of the real image on the detection surface of camera 410 is:

[0066]

[0067] Among them, f 100 is the effective focal length of the eyepiece set 100, f 600 is the effective focal length of the imaging lens assembly 600, f 421 is the effective focal length of the first camera lens group 421, f 422 is the effective focal length of the second camera lens group 422, h is the image height of the virtual image AA of the corneal light reflection point, θ is the angle between the collimated light beam and the optical axis, and ρ is the curvature radius of the central area of ​​the cornea.

[0068] It can be seen that the image height of the real image formed on the detection surface of the camera 410 is proportional to the corneal curvature radius.

[0069] If a point light source array 310 distributed on a circle centered on the main optical axis is used, the radius R of the circle is obtained by performing circular fitting on the positions of the real images formed by the multiple point light sources of the point light source array 310 on the detection surface of the camera 410, and the corneal curvature radius ρ is calculated according to formula (8).

[0070]

[0071] Similar to Figure 2 In the embodiment of the present application, the corneal curvature measurement system may also include an OCT optical path 200 for measuring relevant parameters such as the axial length of the eyeball being measured, and the OCT optical path 200 is connected to the main optical path through a dichroic mirror 210.

[0072] In another possible implementation, if Figure 4As shown, the light source module 300 includes a point light source array 310, a first light source lens group 610, a light source aperture 340 and a beam splitter 320 arranged on the light-emitting side of the point light source array 310, and the corneal curvature measurement system further includes an imaging lens group 600 arranged between the beam splitter 320 and the focal plane inside the eyepiece group 100. The light emitted from the point light source array 310 passes through the first light source lens group 610 and the light source aperture 340 in sequence, and is merged into the main light path through the beam splitter 320. After passing through the imaging lens group 600, a point light source array real image CC is formed at the focal plane inside the eyepiece group 100, and then collimated by the eyepiece group 100, falls on the circumference of the cornea at the same latitude, and is reflected by the cornea to form a virtual image AA of the corneal light reflection point. The light beam reflected by the cornea passes through the eyepiece group 100, the diaphragm 500 (virtual diaphragm), the imaging lens group 600, and the beam splitter 320 in sequence, and forms a real image BB of the corneal light reflection point on the intermediate image plane, and then passes through the second camera lens group 422 of the camera lens group 420, the camera lens group diaphragm 510, and the first camera lens group 421 in sequence to form a real image on the detection surface of the camera 410. The camera lens group diaphragm 510 is conjugately imaged by the second camera lens group 422 and the imaging lens group 600 in the camera lens group 420 near the back focal plane of the eyepiece group 100 to form a virtual diaphragm (diaphragm 500), which ensures that the imaging system is telecentrically imaged outside the eyepiece group 100 without affecting the space inside the eyepiece group 100, allowing the system to use a short focal length eyepiece in conjunction with other imaging optical paths such as the OCT optical path 200 to achieve a large range of fundus scanning, and allowing other imaging optical paths such as the OCT optical path 200 to move forward and backward to adapt to eyes with different diopters.

[0073] In this embodiment, the imaging lens assembly 600 realizes Figure 3 The function of the second light source lens group 620 in the projection light path is to be shared by the imaging light path and the projection light path, which simplifies the number of optical elements in the light path system, reduces the complexity of the system, and achieves an overall optimized layout of the light path system.

[0074] The calculation of the image height of the real image on the detection surface of the camera 410 and the corneal curvature is the same as formula (7) (8) and will not be repeated here.

[0075] In a possible implementation, Figure 5 As shown, the multiple point light sources in the point light source array 310 are distributed on the same circumference with the main optical axis as the center.

[0076] For example, Figure 5 As shown, the point light source array 310 includes twelve point light sources composed of twelve LED lamp beads, which are evenly arranged on a circle centered on the main optical axis. It should be noted that Figure 5 The evenly arranged point light sources shown in the figure are only for illustration and are not limited to being evenly arranged on a circle.

[0077] In a feasible implementation manner, the multiple point light sources in the point light source array 310 are distributed on multiple circles with the main optical axis as the center, and multiple point light sources are arranged on each circle.

[0078] For example, Figure 6 or Figure 7 As shown, the multiple point light sources in the point light source array 310 are distributed on three circumferences. Figure 6 and Figure 7 Of course, according to the parameter requirements of the corneal reflection points to be formed, the number of point light sources in the point light source array 310 can be set to other values, and multiple point light sources can be distributed on two, four or more circles.

[0079] The array of point light sources may also include a fixation lamp for assisting the eye under test to fixate. The light projected by the fixation lamp forms an image on the focal plane inside the eyepiece assembly 100, and is further projected to the fundus of the eyeball under test to achieve fixation of the eyeball under test. The fixation lamp and the corneal light reflection point light source are located on the same plane. These fixation lamps may be used alone for fixation, or they may have a dual role, that is, at least a part of the point light source may be used (but not necessarily) as a fixation light source, or may be used (but not necessarily) as a corneal light reflection point light source.

[0080] For example, Figure 8-10 As shown, examples of three types of point light sources in the point light source array 310 being distributed on multiple circles with the main optical axis as the center are respectively shown. Figure 8 In the figure, the point light source array 310 is arranged in a rectangular array, which includes a point light source (fixation lamp 311) located in the center for fixation. The point light sources at other positions outside the center are distributed on a plurality of concentric circles with the central point light source as the center according to their distance from the center. Two or more point light sources are distributed on each concentric circle. These point light sources may be used for fixation or as corneal reflection point light sources, or they may also play a dual role, that is, at least a part of the point light sources may be (but not necessarily) used as fixation light sources or as corneal reflection point light sources.

[0081] The point light sources constituting the point light source array 310 may also be arranged in other patterns, such as Fig. 9 and Fig.10 The principles are similar and will not be described in detail.

[0082] In addition to the above Figure 5-Figure 12 In addition to the point light source setting example, the multiple point light sources of the point light source array 310 can also be arranged in other forms, which is not strictly limited in the embodiments of the present application.

[0083] In a feasible implementation, the point light source array 310 further includes a fixation lamp 311 located at the center of the point light source array, and / or one or more of the point light source array serve as both corneal reflection point light sources and fixation light sources.

[0084] like Fig.11 As shown, taking the example that the point light source array 310 includes six point light sources and the six point light sources are arranged on a circle centered on the main optical axis, the point light source array 310 also includes a fixation lamp 311 located in the center. Fig.12 As shown, when the point light source array 310 includes a situation where multiple point light sources are arranged on three circles and each circle, the fixation lamp 311 is also located on the same plane as the corneal light reflection point light source, and the fixation lamp 311 is located at the center of the point light source array 310 formed by the three circles.

[0085] Before the corneal curvature measurement system of the embodiment of the present application measures the corneal curvature of the eye being measured, the system is usually calibrated first.

[0086] Multiple standard reflecting spheres of known diameters are measured in sequence, and the radii of the rings of the real images formed by the point light source array 310 on the detection surface of the camera 410 are recorded respectively. Linear fitting is performed on the measured data to obtain the radii of the standard reflecting sphere and the real image ring. Under the paraxial light approximation, the radius of the real image ring is linearly proportional to the curvature radius of the measured sphere.

[0087] The ideal state cannot be achieved in the actual measurement optical path. In order to improve the measurement accuracy as much as possible, high-order terms can be added to the fitting formula. For example, a second-order fitting is used:

[0088] ρ=a0+a1R+a2R 2 (9)

[0089] Where ρ is the curvature radius of the known spherical surface, and R is the radius of the real image circumference formed by the corneal reflection points distributed on the same circumference in the measured light source array on the detection surface of the camera 410. Substituting three or more known spherical surface curvature radii and corresponding R values, the standard fitting calculation formula can be used to obtain the fitting coefficients a0, a1, a2, etc.

[0090] For a reflective spherical surface of unknown radius or the cornea of ​​the eye being measured, the radius R of the real image formed on the detection surface of the camera 410 is substituted into formula (9) to obtain the curvature radius of the reflective spherical surface or the cornea being measured.

[0091] For the point light source array 310, an experiment is conducted with twelve point light sources on a circumference. The real image received by the detection surface of the camera 410 is as follows: Fig.13, which is a real image of the point light source array 310 after being reflected by a spherical surface with a known curvature radius. After performing circular fitting on multiple spherical real images with known curvature radii, a relationship diagram between the circular radius of the real image received by the detection surface of the camera 410 and the curvature radius of the spherical surface with known curvature used for calibration is plotted. Fig.14 In the example, the measured values ​​are a0 = -0.3158 mm, a1 = 11.368, a2 = -0.8181 mm. -1 .

[0092] In some other application scenarios, the corneal curvature measurement system of the embodiment of the present application is not limited to the measurement of the corneal curvature radius of the measured eyeball. For example, it can also be used to measure the curvature radius of some spherical reflective surfaces that are not convenient for contact measurement, such as spherical reflectors, spherical optical lenses, or the surface curvature radius of metal balls and glass balls.

[0093] Another aspect of the present application is to provide a corneal curvature measurement device, including any of the above corneal curvature measurement systems. A flexible housing packaging structure is configured outside the corneal curvature measurement system to form a corneal curvature measurement device, which can be flexibly used in medical and other related fields.

[0094] In a feasible embodiment, the point light source array 310 of the corneal curvature measurement system includes a circuit board and LED lamp beads distributed on the circuit board, or the point light source array 310 of the corneal curvature measurement system includes a light source and a mask with a small hole array covered on the light output side of the light source.

[0095] The point light source array 310 is prepared by evenly distributing LED lamp beads as point light sources on the same circumference or multiple circumferences on the circuit board. The preparation process is simple and easy to operate. The circuit board is arranged at the focal plane inside the eyepiece group 100, and multiple LED lamp beads all emit light in the direction of the eyepiece group 100. The prepared point light source array 310 is efficiently integrated and modular, and is also convenient for installation and debugging in the corneal curvature measurement device.

[0096] When a point light source array 310 is used as a light source and a mask plate with an array of small holes is set on the light emitting side of the light source, an array light source of LED lamp beads can be selected in the same way, or a surface light source can be used, and a mask plate with an array of small holes is covered on the emitting surface, and the array light is emitted according to the arrangement of the array of small holes on the mask plate.

[0097] In addition, for applications of measuring the radius of corneal curvature, part or all of the point light sources on the circuit board can be used as light sources for measuring the corneal curvature of the eye being measured, as point light sources for forming a virtual image AA of the corneal reflection point on the cornea, and can also be used in whole or in part as fixation light sources.

[0098] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A keratometer system, characterized in that: The invention comprises an eyepiece group and a light source module, a camera module and an aperture located inside the eyepiece group. The light source module comprises a point light source array. The point light source array emits light or forms an image on a focal plane inside the eyepiece group. The light is emitted through the eyepiece group as a plurality of collimated light beams and enters an eyeball to be measured outside the eyepiece group. The plurality of collimated light beams respectively fall on the circumference of the same latitude of the cornea and are reflected by the cornea to form a virtual image of a corneal light reflection point. The camera module comprises a camera and a camera lens group. The plurality of collimated light beams are reflected by the cornea and pass through the eyepiece group, the aperture and the camera lens group in sequence to form a real image on a detection surface of the camera. The corneal curvature is calculated according to the position information of the corneal light reflection point in the real image.

2. The keratometer system according to claim 1, characterized in that: The diaphragm is located at the focal plane inside the eyepiece group, and the optical system formed by the eyepiece group and the camera lens group is telecentric imaging on one side of the eyepiece group; the diaphragm includes a physical diaphragm, and the physical diaphragm is arranged on the focal plane inside the eyepiece group; or, the diaphragm includes a virtual diaphragm, and a conjugate image is formed on the focal plane inside the eyepiece group by a camera lens group diaphragm arranged in the optical path as the virtual diaphragm.

3. The keratometer system according to claim 2, characterized in that: The light source module also includes a beam splitter arranged on the light-emitting side of the point light source array, and a first light source lens group, a light source aperture and a second light source lens group are also arranged between the point light source array and the beam splitter. The light emitted by the point light source array passes through the first light source lens group, the light source aperture and the second light source lens group in sequence, and then passes through the beam splitter to merge into the main light path, and forms a real image at the focal plane inside the eyepiece group, and then passes through the eyepiece group to fall on the circumference of the same latitude of the cornea and is reflected by the cornea to form a virtual image; an imaging lens group is also arranged between the beam splitter and the camera lens group, and the virtual image formed on the cornea passes through the eyepiece group, the aperture and the imaging lens group in sequence, and then forms an image on the intermediate image plane, and then passes through the camera lens group to form a real image on the detection surface of the camera.

4. The keratometer system according to claim 2, characterized in that: The light source module also includes a beam splitter arranged on the light-emitting side of the point light source array, and a first light source lens group and a light source aperture are also arranged between the point light source array and the beam splitter. The corneal curvature measurement system also includes an imaging lens group arranged inside the eyepiece group; the light emitted from the point light source array passes through the first light source lens group and the light source aperture in sequence, and then passes through the beam splitter to merge into the main light path, and then passes through the imaging lens group to form a real image at the focal plane inside the eyepiece group, and then passes through the eyepiece group to fall on the circumference of the cornea at the same latitude and is reflected by the cornea to form a virtual image, and the virtual image formed on the cornea passes through the eyepiece group, the aperture and the imaging lens group in sequence to form an image on the intermediate image plane, and then passes through the camera lens group to form a real image on the detection surface of the camera.

5. The keratometer system according to claim 3 or 4, characterized in that: The camera lens group includes a first camera lens group, a second camera lens group and a camera lens group diaphragm. The camera lens group diaphragm is arranged between the first camera lens group and the second camera lens group. The camera lens group diaphragm is conjugated with the inner focal plane of the eyepiece group through the second camera lens group and the imaging lens group to form a virtual diaphragm. After the virtual image formed on the cornea becomes a real image on the intermediate image plane, it passes through the second camera lens group, the camera lens group diaphragm and the first camera lens group in sequence to form a real image on the detection surface of the camera.

6. The keratometer system according to claim 1, characterized in that: The plurality of point light sources in the point light source array are distributed on the same circumference with the main optical axis as the center.

7. The keratometer system according to claim 6, characterized in that: There are multiple circles centered on the main optical axis, and the multiple point light sources are distributed on the multiple circles respectively.

8. The keratometer system according to claim 6, characterized in that: The point light source array also includes a fixation lamp, which is located at or imaged at the center of the point light source array, and / or one or more point light sources in the point light source array serve as the fixation lamp.

9. A corneal curvature measurement device, characterized in that: Comprising a keratometer system as described in any one of claims 1-8.

10. The keratometer according to claim 9, characterized in that: The point light source array of the corneal curvature measurement system includes a circuit board and LED lamp beads distributed on the circuit board, or the point light source array of the corneal curvature measurement system includes a light source and a mask with a small hole array covered on the light emitting side of the light source.

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