Corneal topography reconstruction system
By combining MEMS microscope with TOF sensor, the construction of three -dimensional topographic diagrams of the cornea was achieved, and the limitations of traditional corneal measurement methods and high requirements for doctors and patients were solved, and high -precision, safe and reliable corneal measurement was achieved.
Patent Information
- Application Number
- CN202420762193.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-14
- Publication Date
- 2025-01-28
- Estimated Expiration
- 2034-04-14
AI Technical Summary
Traditional corneal imaging measurement methods have limitations in scope, inconvenience in use and insecure in contact measurement, and at the same time, the operation requirements for doctors and patients are too strict.
By combining MEMS microscope with TOF sensor, the two -dimensional information and thickness of the cornea are obtained, so as to achieve the construction of the three -dimensional topographic diagram of the cornea. The system uses non -contact microscope scanning and TOF ranging, which simplifies the measurement process and reduces the operating requirements for doctors and patients.
While ensuring the safety and reliability and accuracy of the measurement, reduce the strict requirements of doctors and patients, simplify the measurement process, and improve the accuracy and efficiency of the corneal topographic diagram.
Smart Images
Figure CN222398292U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of corneal measurement, and more specifically to a corneal topography reconstruction system. Background Art
[0002] Corneal topography plays an important role in the field of ophthalmology. In the screening of ophthalmic diseases and pre- and post-operative evaluation of eye surgery, obtaining accurate corneal information quickly and safely has become an inevitable problem in clinical ophthalmology. With the rapid development of science and technology in the field of medical and engineering integration, simple and easy to use, safe and reliable, highly repeatable and accurate have become the development trend in the field of corneal measurement.
[0003] There are many traditional corneal topography measurement methods and principles, which are mainly divided into two categories: ultrasonic measurement and optical measurement. Ultrasonic measurement has two measurement principles: type A ultrasonic corneal thickness measurement and ultrasonic biomicroscope. While meeting the accuracy requirements, there are range limitations, inconvenience in use, and unsafe contact measurement. Optical measurement includes Pentacam three-dimensional anterior segment analysis, Orbscan-2 anterior segment analysis, optical coherence tomography, corneal endothelial cell microscope, and Lenstar LS900 optical biometry. Although the optical measurement method can avoid direct contact with the surface of the eyeball and ensure the safety and reliability of thickness measurement, it is too strict for doctors and patients. Doctors need to be able to operate the thickness measurement equipment skillfully, and patients need to fully cooperate with the measurement, such as keeping the position of the eyeball unchanged. At the same time, the patient's corneal condition, such as transparency, shape, curvature, etc., is also required to meet the basic prerequisites for measurement. Utility Model Content
[0004] In order to overcome the above-mentioned technical defects, the utility model aims to propose a corneal topography reconstruction system. The system combines a MEMS micromirror with a TOF sensor to obtain two-dimensional information and corneal thickness of the cornea, which helps to construct a topographic map containing three-dimensional information of the cornea, thereby ensuring safe, reliable and accurate measurements while reducing the strict requirements of traditional measurement methods on doctors and patients, ultimately simplifying the measurement process.
[0005] The utility model provides a corneal topography reconstruction system, comprising:
[0006] a first scanning unit, the first scanning unit being composed of a laser, a MEMS micromirror and a photoelectric sensor, the laser being used to emit a laser beam toward the MEMS micromirror, the MEMS micromirror being used to reflect the laser beam onto the cornea of a human eye and scan the surface of the cornea, and the photoelectric sensor being used to receive the reflected scanning beam of the cornea;
[0007] a second scanning unit, the second scanning unit being composed of a TOF sensor and a receiver, the TOF sensor being used to emit a laser beam toward the cornea of a human eye and to locate and measure the scanning beam emitted by the MEMS micromirror, and the receiver being used to receive a reflected measurement beam from the cornea;
[0008] A computer is used to exchange data with the first scanning unit and the second scanning unit.
[0009] Preferably, the emission light beam of the laser is opposite to the MEMS micromirror, and the MEMS micromirror can receive the emission light beam from the laser, and when the laser emits the laser beam toward the MEMS micromirror, the MEMS micromirror can reflect the laser beam to the surface of the eyeball.
[0010] Preferably: the photoelectric sensor is connected to a computer, and a signal processor or a signal processing circuit is provided between the photoelectric sensor and the computer, wherein the signal processor or the signal processing circuit is used to convert the analog signal of the photoelectric sensor.
[0011] Preferably, the TOF sensor and the receiver are both opposite to the surface of the patient's eyeball.
[0012] Preferably, a timer is arranged in the receiver, and the timer is used to record the time difference from the emission to the return of the laser beam, and the computer is connected to the TOF sensor and the receiver.
[0013] Preferably, the distance value between the TOF sensor and the patient's cornea and the distance value between the receiver and the patient's cornea are consistent with each other.
[0014] Preferably, the MEMS micromirror is further provided with a signal generator, which is connected to the MEMS micromirror. When in use, the signal generator is used to control the MEMS micromirror to perform fast-axis and slow-axis motions.
[0015] From the above content, it can be seen that the utility model provides a corneal topography reconstruction system, which mainly combines micromirror scanning, TOF ranging and computer. When in use, the micromirror is used to perform high-resolution scanning of the Lissajous trajectory, and the TOF sensor is used to perform accurate distance measurement. This non-contact collection method can effectively collect the patient's corneal data and transmit it to the computer. The computer then generates a detailed corneal topography based on this data. This design not only realizes the miniaturization and low power consumption of the system, but also improves the accuracy and efficiency of corneal topography acquisition. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 The present invention is a structural diagram of a corneal topography reconstruction system.
[0017] Figure 2 Schematic diagram of using a laser source and MEMS micromirror to generate a Lissajous trajectory to scan the cornea.
[0018] Figure 3 The schematic diagram of the TOF sensor measuring the distance from a point on the cornea to the TOF sensor. D is the distance from the corneal edge to the TOF sensor, d represents the distance from any point on the cornea to the TOF sensor, and h is the corneal thickness corresponding to any point on the cornea. There is a mathematical relationship h = Dd.
[0019] Figure 4 This is the model diagram of the system.
[0020] Figure 1-Figure 4 In Chinese: 100-computer; 101-laser; 102-MEMS micromirror; 103-photoelectric sensor; 104-TOF sensor; 105-receiver. DETAILED DESCRIPTION
[0021] The following will be combined with the embodiments to clearly and completely describe the technical solution of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.
[0022] Example 1
[0023] As attached Figure 1 To Attachment Figure 2 As shown: a corneal topography reconstruction system includes a computer 100, a first scanning unit and a second scanning unit, wherein the first scanning unit is composed of a laser 101, a MEMS micromirror 102 and a photoelectric sensor 103, wherein the emission light beam of the laser 101 is opposite to the MEMS micromirror 102, and the MEMS micromirror 102 can receive the emission light beam from the laser 101. When the laser 101 emits a laser beam toward the MEMS micromirror 102, the MEMS micromirror 102 can reflect the laser beam to the surface of the eyeball (i.e., the corneal surface), and then the corneal surface reflects the laser beam to the photoelectric sensor 103. When the photoelectric sensor 103 receives the reflected laser beam from the cornea, the acquired data can be converted and transmitted to the computer 100.
[0024] At the same time, the MEMS micromirror 102 has the characteristics of a slow axis and a fast axis. When the MEMS micromirror 102 is driven to vibrate along the fast axis and the slow axis at a certain frequency and amplitude, a resonance phenomenon will occur. In this resonant state, the laser beam irradiated on the micromirror will be reflected along with the vibration of the micromirror and form a Lissajous figure track. These reflected laser beams are projected onto the cornea in the track of the Lissajous figure to form a scanning beam, thereby realizing dynamic Lissajous scanning of the cornea. During the scanning process, multiple nodes will be formed on the track. On the other hand, the photoelectric sensor 103 is responsible for receiving the laser beam reflected from the cornea and scanned according to the Lissajous figure track.
[0025] In addition, it should be noted that the slow axis and fast axis functions of the MEMS micromirror 102 and the Lissajous pattern mentioned above are all existing well-known technologies, and the laser 101 emits a laser beam that is safe and harmless to human eyes.
[0026] Furthermore, in order to facilitate data exchange between the photoelectric sensor 103 and the computer 100, a signal processor or a signal processing circuit is provided between the photoelectric sensor 103 and the computer 100, wherein the signal processor or the signal processing circuit is used to convert the analog signal of the photoelectric sensor 103, and then connect the signal to the computer 100 after conversion. Specifically, since the signal in the photoelectric sensor 103 is an analog signal, by providing a corresponding signal processor signal processing circuit, the analog signal can be amplified, filtered, and then A / D converted, and only after the A / D conversion will it become a digital signal, and then it can be connected to the computer 100.
[0027] At the same time, after the digital signal is connected to the computer 100, the point cloud information of the corneal reflection is collected by using the Labview software in the computer 100, and then the initial point cloud information is processed by combining Qt5.14.0 with VS2017 to obtain a two-dimensional image of the corneal surface. In addition, the Qt platform can also configure the Opencv environment and combine it with the deep learning model to post-process the subsequent collected images.
[0028] The following is a detailed process of the computer 100 processing the point cloud information:
[0029] After the photoelectric sensor 103 passes through its signal processing circuit, it is connected to the computer 100, and the point cloud information reflected by the cornea is collected by Labview in the computer 100, and then the original data of the point cloud is filtered and denoised by the statistical filtering algorithm, radius filtering algorithm and moving least squares algorithm of the computer 100; then the curvature downsampling method is used to simplify the point cloud, and the perturbation TrICP algorithm is first used to pre-stitch the surface, and the point-to-surface ICP algorithm is used for precise stitching, and finally the two-dimensional image containing the two-dimensional information of the corneal surface obtained by Lissajous scanning is obtained by optimizing the posture graph. In addition, it should be noted that in this embodiment, the implementation methods and processes of the functions such as instruction reception and image generation of the computer 100 are all prior art, that is, the Labview software, Qt5.14.0, VS2017, Qt platform, and the algorithms involved in the above content are all prior art.
[0030] Furthermore, in order to facilitate driving the micromirror to move in the fast axis and slow axis, a signal generator is also configured at the MEMS micromirror 102. During operation, the signal generator is used to generate two square wave signals with specific frequencies and amplitudes. The two signals are respectively sent to the fast axis and slow axis of the micromirror to drive the micromirror to vibrate at the set frequency to achieve resonance.
[0031] Example 2
[0032] As attached Figures 1 to 4As shown, the second scanning unit is composed of a TOF sensor 104 and a receiver 105, wherein the receiver 105 is a receiver that comes with the TOF sensor 104 itself, and the receiver is a photoelectric sensor, which is usually set on the TOF sensor 104 during installation, and its main function is to receive reflected light. The TOF sensor 104 and the receiver 105 are both opposite to the surface of the patient's eyeball, and the TOF sensor 104 has the function of emitting a light source (laser). When the TOF sensor 104 is turned on, the light source can be irradiated at each node of the Lissajous scanning trajectory, and then the cornea reflects the light source of the TOF sensor 104, and the receiver 105 receives it during the reflection. At the same time, the receiver 105 has a built-in timer, and the timer is mainly used to record the time difference from the emission to the return of the laser beam, so as to calculate the value of the distance, which is helpful to measure the corneal thickness. Specifically, when the MEMS micromirror 102 first performs a Lissajous scan on the cornea, there will be multiple nodes on the scanning track. At this time, the light source of the TOF sensor 104 is activated to illuminate the cornea, and the positions of these nodes on the cornea are located and marked. Then the laser 101 and the TOF sensor 104 are turned off, and the MEMS micromirror 102 ends the Lissajous scanning process on the cornea; then the TOF sensor 104 is turned on again, so that the laser it emits illuminates the position of the corneal mark point, and the laser reaches the corneal surface and is reflected to the receiver 105 (or TOF sensor 104), so that the time difference between the laser being emitted and returning from the cornea to the receiver 105 (or TOF sensor 104) can be obtained, and then the corneal thickness can be measured by the time difference.
[0033] Furthermore, the distance value between the TOF sensor 104 and the patient's cornea and the distance value between the receiver 105 and the patient's cornea are consistent with each other. Through this design, when the laser of the TOF sensor 104 is emitted and returned, the time difference calculated can remain consistent. By keeping the TOF sensor 104 and the receiver 105 equidistant from the cornea, the accuracy and reliability of the measurement can be improved, thereby making the measurement result of the corneal thickness more accurate.
[0034] Furthermore, the TOF sensor 104 and the receiver 105 are both connected to the computer 100. When in use, the data measured by the TOF sensor 104 or the receiver 105 can be uploaded to the computer 100, such as the time difference data between the laser and the cornea. The computer 100 then calculates according to the formula to measure the thickness of the cornea.
[0035] Based on the above embodiment, the following are the steps for corneal topography reconstruction:
[0036] In the first step, the laser 101 is turned on and adjusted so that the laser beam is irradiated onto the MEMS micromirror 102 at a certain angle (which can be 10-45 degrees).
[0037] In the second step, an external signal generator is used to generate two square wave signals of a certain frequency and amplitude, which are input into the fast axis and slow axis of the micromirror to drive the MEMS micromirror 102 to resonate at a certain frequency. (It should be noted that both the fast axis and the slow axis are 50% square wave signals, where the signal generator inputs the fast axis signal: the amplitude is 2.5V, the frequency is 1000-2000Hz, and the signal inputs the slow axis signal: the amplitude is 2.5V, the frequency is 500-1000Hz, and at the same time, the fast axis starting frequency range is: 1000-2000Hz; the slow axis starting frequency range is: 500-1000Hz. The experimental process selects frequencies within these two ranges to be appropriate).
[0038] In the third step, the laser beam is reflected on the MEMS micromirror 102 and scans the cornea in a Lissajous trajectory, and the photoelectric sensor 103 collects the information reflected by the cornea and connects it to the signal processing circuit.
[0039] In the fourth step, the computer 100 performs point cloud image processing on the collected corneal reflection information to obtain a two-dimensional image of the corneal surface (hereinafter referred to as a two-dimensional image).
[0040] Step 5: Start the light source of the TOF sensor 104 to illuminate the cornea and mark each node of the laser beam Lissajous scanning trajectory (such as Figure 1 The position of the cornea (as shown) and the corresponding position in the two-dimensional image.
[0041] Step 6: Adjust the TOF sensor 104 so that the laser it emits is irradiated on the position of the corneal mark. After the laser reaches the corneal surface, it is reflected back to the TOF sensor 104 (or the receiver 105). Based on the time difference t between the laser emission and the return from the cornea to the TOF sensor 104 (or the receiver 105), the distance from the corneal mark to the TOF sensor 104 can be calculated. (c is the speed of light). It should be noted that the formula here is a relationship between the existing thickness and the measured distance, which belongs to the existing public technology.
[0042] Step 7: Obtain the distance D between the corneal edge point and the TOF sensor 104 and the distance d between any mark point on the cornea and the TOF sensor 104 through the steps of step 6.
[0043] Step 8. According to the formula, obtain the corneal thickness value h corresponding to any marked point on the cornea.
[0044] In the ninth step, the corneal thickness corresponding to all the marked points on the cornea is calculated, and the corneal thickness corresponding to each marked point is matched with the coordinate point of the two-dimensional image in the computer 100. The numerical value of the thickness can be replaced by colors of different shades, thereby converting the two-dimensional image of the cornea into a corneal topography map with thickness information.
[0045] It should be noted that in the above-mentioned corneal topography reconstruction steps, the implementation and calculation formulas of functions such as command sending, command receiving, image scanning, image processing, etc. are all existing technologies.
[0046] Based on the above embodiments, Figure 1 and Figure 4 As shown, the present solution also provides a model building diagram for the system, which also includes components such as an inspection table, a pad, and a chin rest pillow. The inspection table is the basis for building the system, and its position and height are adjustable for efficient testing. The function of the pad is to adjust the height of the MEMS micromirror 102 to ensure that the laser beam emitted by the laser 101 can accurately irradiate the micromirror. The chin rest pillow provides a comfortable support for the patient to help them maintain a stable posture during the examination. When the patient places their chin on the rest pillow, their eyes maintain a relative position with the inspection table.
[0047] In the specific arrangement process, the pad and components such as the laser 101, the MEMS micromirror 102, the photoelectric sensor 103, the TOF sensor 104 and the receiver 105 need to be installed on the inspection table. In particular, the MEMS micromirror 102 should be accurately arranged above the pad. In addition, it should be noted that the inspection table, the pad and the chin rest are all existing conventional equipment. Their use in this system is to ensure the convenience of the detection process and the comfort of the patient.
[0048] Based on the above embodiment, the following are the implementation steps of building a system for corneal topography detection:
[0049] In the first step, the patient places his chin on the chin rest and maintains a relatively stable position in a comfortable posture.
[0050] The second step is to turn on the laser 101 so that the laser beam is irradiated onto the micromirror and the micromirror is driven at the same time so that the micromirror reflects light to perform a Lissajous scan on the cornea.
[0051] In the third step, the photoelectric sensor 103 receives the reflection information of the cornea, and processes the information through the computer 100 to obtain the two-dimensional information of the cornea.
[0052] The fourth step is to start the TOF sensor 104 and let its light source illuminate each node of the Lissajous scanning trajectory. The receiver 105 receives the light beam reflected by the cornea and obtains the corneal thickness at the corresponding position by recording the time difference between the emission and reception of the light beam.
[0053] In the fifth step, the corneal thickness obtained at each position is matched with the points on the two-dimensional corneal image obtained by Lissajous scanning by computer 100, and the corneal topography is obtained by point cloud processing.
[0054] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that any technician familiar with this technical field can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed in the present application, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application. Therefore, the protection scope of the present application should be described in the protection scope of the claims.
Claims
1. A corneal topography reconstruction system, characterized in that: include: a first scanning unit, the first scanning unit being composed of a laser, a MEMS micromirror and a photoelectric sensor, the laser being used to emit a laser beam toward the MEMS micromirror, the MEMS micromirror being used to reflect the laser beam onto the cornea of a human eye and scan the surface of the cornea, and the photoelectric sensor being used to receive the reflected scanning beam of the cornea; a second scanning unit, the second scanning unit being composed of a TOF sensor and a receiver, the TOF sensor being used to emit a laser beam toward the cornea of a human eye and to locate and measure the scanning beam emitted by the MEMS micromirror, and the receiver being used to receive a reflected measurement beam from the cornea; A computer is used to exchange data with the first scanning unit and the second scanning unit.
2. A corneal topography reconstruction system according to claim 1, characterized in that: The emission light beam of the laser is opposite to the MEMS micromirror, and the MEMS micromirror can receive the emission light beam from the laser. When the laser emits a laser beam toward the MEMS micromirror, the MEMS micromirror can reflect the laser beam to the surface of the eyeball.
3. A corneal topography reconstruction system according to claim 1, characterized in that: The photoelectric sensor is connected to a computer, and a signal processor or a signal processing circuit is arranged between the photoelectric sensor and the computer, wherein the signal processor and the signal processing circuit are used to convert the analog signal of the photoelectric sensor.
4. A corneal topography reconstruction system according to claim 1, characterized in that: The TOF sensor and the receiver are both opposite to the surface of the patient's eyeball.
5. A corneal topography reconstruction system according to claim 1, characterized in that: A timer is arranged in the receiver, and the timer is used to record the time difference from the emission to the return of the laser beam. The computer is connected with the TOF sensor and the receiver.
6. A corneal topography reconstruction system according to claim 1, characterized in that: The distance value between the TOF sensor and the patient's cornea and the distance value between the receiver and the patient's cornea are consistent with each other.
7. A corneal topography reconstruction system according to claim 1, characterized in that: The MEMS micromirror is also provided with a signal generator, which is connected to the MEMS micromirror. When in use, the signal generator is used to control the MEMS micromirror to perform fast-axis and slow-axis motions.