Cornea confocal high-speed imaging dislocation distortion correction system

Abstract

According to the cornea confocal high-speed imaging dislocation distortion correction system provided by the invention, the diaphragm for providing position reference is additionally arranged on the main image plane in the cornea confocal scanning imaging light path, and the dislocation image is corrected through the position of the diaphragm in the imaging process; high-speed bidirectional image dislocation distortion caused by a non-ideal motion state of the resonance galvanometer is overcome, and bidirectional high-speed scanning imaging is realized.

Description

Technical Field

[0001] The present application relates to optical detection technology, and in particular to a corneal confocal high-speed imaging misalignment and distortion correction system. Background Art

[0002] Infectious keratitis is the most common blinding eye disease after cataracts in my country, with approximately 2 million patients suffering from monocular blindness due to corneal infection each year. Patients with infectious keratitis are prone to recurrent attacks and prolonged illness, and are often confused with other diseases, resulting in a high misdiagnosis rate and great difficulty in treatment. Corneal confocal microscopy can obtain clear cellular-level images of each layer of the cornea, enabling non-invasive and rapid diagnosis of corneal infectious diseases.

[0003] Corneal confocal imaging faces a challenge that the eyeball shakes unconsciously. To overcome this problem, the imaging speed needs to be increased. The solution is to use two special galvanometers: resonant galvanometers and galvanometers. These two galvanometers can quickly scan the imaging surface in two directions, thereby greatly improving the overall imaging speed. Among them, the resonant galvanometer is a deflection mechanism for high-speed scanning based on the resonance principle. This mechanism usually has a natural frequency. When the frequency of the external driving force matches this natural frequency, resonance occurs, thereby achieving efficient and high-speed scanning. In this process, the angular motion of the resonant galvanometer is usually carried out according to the cosine law, which means that its angular velocity changes with time, and the maximum angular velocity occurs at the peak and trough of the cosine waveform. However, in terms of the speed of the outbound and return strokes, if only the cosine waveform is considered, theoretically at the same angular position (such as halfway from the peak to the trough and halfway from the trough to the peak), the speed of the outbound and return strokes should be the same. However, in actual applications, the movement of the resonant galvanometer may be affected by many factors, such as friction, damping, and nonlinear effects of the mechanical structure, which may cause certain differences in the speed of the outbound and return strokes in actual measurements. This causes the odd and even rows to be misaligned when the outbound and return strokes are used for imaging (the outbound stroke is the odd-numbered rows of the image, and the return stroke is the even-numbered rows of the image). At the same time, since the frequency of the resonant galvanometer will drift during operation, the misalignment of the odd and even rows and the inherent nonlinear distortion of the resonant galvanometer scanning are superimposed together, and a simple alignment algorithm cannot be used to correct the image misalignment. Summary of the invention

[0004] In view of this, it is necessary to provide a corneal confocal high-speed imaging misalignment and distortion correction system that can correct misaligned images in order to address the technical defects of high-speed bidirectional image misalignment and distortion existing in the current corneal confocal high-speed imaging misalignment and distortion correction system.

[0005] To solve the above problems, this application adopts the following technical solutions:

[0006] One of the purposes of the present application is to provide a corneal confocal high-speed imaging misalignment correction system, comprising: a laser, a beam splitter, a scanning galvanometer, a scanning lens, a main image plane aperture, a tube lens, an objective lens, a pinhole lens, a pinhole, a detector and an imaging control unit, wherein the imaging control unit is electrically connected to the laser, the detector and the scanning galvanometer, wherein:

[0007] The illumination light beam emitted by the laser is reflected by the beam splitter and then incident on the scanning galvanometer. The illumination light beam scanned by the scanning galvanometer is incident on the scanning lens and then enters the tube lens through the main image plane aperture. The illumination light beam passing through the tube lens is then focused on the cornea through the objective lens. The objective lens collects the light signal from the cornea. The light signal then passes through the tube lens, the main image plane aperture, the scanning lens, the scanning galvanometer, the beam splitter, the pinhole lens in sequence and then is detected by the detector through the pinhole. The detector converts the acquired light signal into an electrical signal and transmits it to the imaging control unit. The imaging control unit receives the electrical signal and reconstructs the scanned image.

[0008] The imaging control unit controls the scanning galvanometer to perform lateral scanning and longitudinal scanning to realize point scanning imaging of the corneal confocal system, and controls the position of the main image plane aperture during the scanning imaging process to correct the misaligned image.

[0009] In some embodiments, the imaging control unit drives the scanning galvanometer to scan horizontally to generate a resonance waveform, the displacement and time of which conform to the law of the cosine function, and in one cycle, it can be divided into two scanning parts, namely, the outbound scan and the return scan;

[0010] The imaging control unit drives the scanning galvanometer to scan longitudinally to generate a galvanometer waveform. When the resonance waveform completes a forward or return scan, its position is switched to the position of the next row.

[0011] In some embodiments, some values ​​of the main image plane stop in the data sequence obtained by scanning imaging are characteristic intensity values ​​of the main image plane stop, and the specific process is as follows:

[0012] a) Sampling: For each data sampling, i.e., the scanning galvanometer swings for one cycle, the number of sampling points is N, and the sampling data is {s[n], n=1→N};

[0013] b) Outbound and return data segmentation: Obtain the boundary positions n1, n2, n3, n4 between the characteristic intensity value and the ordinary intensity value of the main image plane aperture, then the outbound data is {s[n], n=n1→n2}, and the return data is {s[n], n=

[0014] n3→n4}, at this time, the return and outbound data are guaranteed by the main image plane aperture to have an imaging area range.

[0015] In some embodiments, the imaging control unit controls the position of the main image plane aperture to correct the misaligned image, specifically including the following:

[0016] Perform conventional cosine nonlinear distortion correction on the outbound data and the return data respectively to obtain odd-numbered line and even-numbered line image data;

[0017] The image data of the odd-numbered lines and the even-numbered lines are combined to form a completed corneal confocal image.

[0018] In some of the embodiments, the steps of performing conventional cosine nonlinear distortion correction on the outbound data and the return data to obtain the odd-numbered lines and the even-numbered lines of image data respectively include:

[0019] Corresponding to the outbound path, which is the odd-numbered row of the image, the sampling point number corresponding to the pixel coordinate x is:

[0020]

[0021] pass The rounded value is Then the intensity value corresponding to the pixel coordinate x is

[0022] Corresponding to the return path, which is the even-numbered row of the image, the sampling point number corresponding to the pixel coordinate x is:

[0023]

[0024] pass The rounded value is Then the intensity value corresponding to the pixel coordinate x is

[0025] Among them: the number of pixels in a row is determined by X max , the pixel value of each row is I l (x),x=1→X max ,l is the line number.

[0026] In some of the embodiments, an objective lens driving unit is further included, and the objective lens driving unit can drive the objective lens to move. The imaging control unit is electrically connected to the objective lens driving unit and is used to control the operation of the objective lens driving unit.

[0027] This application adopts the above technical solution, and its beneficial effects are as follows:

[0028] The corneal confocal high-speed imaging misalignment and distortion correction system provided in the present application adds an aperture that provides a position reference to the main image plane in the corneal confocal scanning imaging light path, and corrects the misaligned image through the position of the aperture during the imaging process, thereby overcoming the high-speed bidirectional image misalignment and distortion caused by the non-ideal movement of the resonant galvanometer and realizing bidirectional high-speed scanning imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 This is a schematic diagram of the structure of the corneal confocal high-speed imaging misalignment correction system provided in Example 1 of the present application.

[0031] Figure 2 This is a schematic diagram of the control waveform and image of bidirectional image scanning provided in Example 1 of the present application.

[0032] Figure 3 Embodiment 1 of the present invention provides the method of obtaining outbound and return data based on aperture characteristics.

[0033] Figure 4 This is a flowchart of image misalignment and distortion processing based on aperture provided in Example 1 of the present invention.

[0034] Figure 5 This is the correspondence between the outbound and return image row pixels and the sampling sequence provided by Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0035] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0036] In the description of the present application, it should be understood that the terms "upper", "lower", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0038] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0039] Example 1

[0040] See also Figure 1 , which is a schematic diagram of the structure of the corneal confocal high-speed imaging misalignment correction system provided by the embodiment of the present application, includes a laser 11, a beam splitter 12, a scanning galvanometer 13, a scanning lens 14, a main image plane aperture 15, a tube lens 16, an objective lens 17, a pinhole lens 18, a pinhole 19, a detector 20 and an imaging control unit 21. The technical solution implemented is described in detail below.

[0041] The laser 11 is used to provide an illumination beam. The laser 11 is also electrically connected to the imaging control unit 21, and the imaging control unit 21 can control the illumination beam of the laser 11.

[0042] The beam splitter 12 can realize the reflection of the illumination beam and the transmission of the light from the sample.

[0043] The scanning galvanometer 13 can drive the scanning light spot to traverse the sample imaging area. The scanning galvanometer 13 is also electrically connected to the imaging control unit 21, and the imaging control unit 21 can control the scanning galvanometer 13.

[0044] The scanning lens 14 can correct image distortion caused by partial scanning. The scanning lens 14 is also electrically connected to the imaging control unit 21 , and the imaging control unit 21 can control the scanning lens 14 .

[0045] The main image plane aperture 15 is used to provide a position reference during lateral scanning during the scanning imaging process. The position of the aperture during the imaging process is used to correct the misaligned and distorted image, thereby achieving bidirectional high-speed scanning imaging.

[0046] It should be noted that in practice, the position of the main image plane aperture 15 can be adjusted manually or automatically to better correct the misaligned and distorted image; or the position of the main image plane aperture 15 can be adjusted by the main control unit 21 .

[0047] The tube lens 16 cooperates with the objective lens 17, and the objective lens 17 realizes the illumination of the cornea and the collection of signals from the cornea. The objective lens 17 is also connected to an objective lens driving unit (not shown), which can drive the objective lens to move. The imaging control unit 21 is electrically connected to the objective lens driving unit to control the operation of the objective lens driving unit to realize the movement of the focal plane of the objective lens of the full corneal thickness.

[0048] The detector 19 is used to receive the optical signal from the sample, convert it into an electrical signal and provide it to the imaging control unit 21 for data acquisition.

[0049] The corneal confocal high-speed imaging misalignment correction system provided in the above embodiment of the present application works as follows:

[0050] The illumination light beam emitted by the laser 11 is reflected by the beam splitter 12 and then incident on the scanning galvanometer 13. The illumination light beam scanned by the scanning galvanometer 13 is incident on the scanning lens 14, and then enters the tube lens 16 through the main image plane aperture 15. The illumination light beam passing through the tube lens 16 is then focused on the cornea through the objective lens 17. The objective lens 17 collects the light signal from the cornea. The light signal then passes through the tube lens 16, the main image plane aperture 15, the scanning lens 14, the scanning galvanometer 13, the beam splitter 12, the pinhole lens 18 in sequence, and then passes through the pinhole 19 to be detected by the detector 20. The detector 20 converts the acquired light signal into an electrical signal and transmits it to the imaging control unit 21. The imaging control unit 21 receives the electrical signal and reconstructs the scanned image.

[0051] The imaging control unit 21 controls the scanning galvanometer 13 to perform horizontal scanning and vertical scanning to realize the point scanning imaging of the corneal confocal system, and controls the position of the main image plane aperture 15 during the scanning imaging process to correct the misaligned image.

[0052] In this embodiment, the imaging control unit 21 drives the scanning galvanometer to scan horizontally to generate a resonance waveform, whose displacement and time conform to the law of the cosine function. In one cycle, it can be divided into two scanning parts, the outbound scan and the return scan. The imaging control unit 21 drives the scanning galvanometer to scan longitudinally to generate a galvanometer waveform. When the resonance waveform completes an outbound or return scan, its position switches to the position of the next row.

[0053] See also Figure 2 , which is a schematic diagram of the control waveform and image of the bidirectional image scanning provided in this embodiment. The imaging control unit 21 drives the scanning galvanometer mirror to scan longitudinally to generate a galvanometer waveform. The galvanometer mirror drives the longitudinal scanning. When the resonance waveform completes a forward (return) scan, its position switches to the position of the next row (such as Figure 2a represents the waveform of the bidirectional scanning process). Figure 2 Figure b (bidirectional scanning image diagram) shows the process of bidirectional scanning, where the blue lines can be the image lines obtained by the point scanning imaging of the outgoing (returning) process of the resonant galvanometer, and the red lines are the image lines obtained by the point scanning imaging in the returning direction.

[0054] Furthermore, since a main image plane aperture 15 is added at the main image plane of the corneal confocal imaging system, some values ​​in the data sequence obtained by scanning imaging are characteristic intensity values ​​of the aperture (such as Figure 3 )The process is as follows:

[0055] a) Sampling: For each data sampling, i.e., the scanning galvanometer swings for one cycle, the number of sampling points is N, and the sampling data is {s[n], n=1→N};

[0056] b) Segmentation of outbound and return data: obtain the boundary positions n1, n2, n1, n4 of the characteristic intensity values ​​and the ordinary intensity values ​​of the main image plane aperture, then the outbound data is {s[n], n=n1→n2}, and the return data is {s[n], n=n3→n4}. At this time, the return and outbound data are guaranteed by the main image plane aperture to have the range of their imaging area.

[0057] Furthermore, the imaging control unit controls the position of the main image plane aperture to correct the misaligned image, specifically including the following: performing conventional cosine nonlinear distortion correction on the outbound data and the return data respectively to obtain odd-numbered and even-numbered lines of image data; and merging the odd-numbered and even-numbered lines of image data into a complete corneal confocal image.

[0058] Furthermore, the steps of respectively performing conventional cosine nonlinear distortion correction on the outbound data and the return data to obtain the odd-numbered lines and the even-numbered lines of image data specifically include:

[0059] Corresponding to the outbound path, which is the odd-numbered row of the image, the sampling point number corresponding to the pixel coordinate x is:

[0060]

[0061] pass The rounded value is Then the intensity value corresponding to the pixel coordinate x is

[0062] Corresponding to the return path, which is the even-numbered row of the image, the sampling point number corresponding to the pixel coordinate x is:

[0063]

[0064] pass The rounded value is Then the intensity value corresponding to the pixel coordinate x is

[0065] Among them: the number of pixels in a row is determined by X max , the pixel value of each row is I l (x),x=1→X max ,l is the line number.

[0066] See also Figure 5 , which is the correspondence between the outbound and return image row pixels and the sampling sequence provided in this embodiment, a) is the correspondence between the outbound row image pixels and the sampling sequence, b) is the correspondence between the return row image pixels and the sampling sequence.

[0067] The corneal confocal high-speed imaging misalignment and distortion correction system provided in the present application adds an aperture that provides a position reference to the main image plane in the corneal confocal scanning imaging light path, and corrects the misaligned image through the position of the aperture during the imaging process, thereby overcoming the high-speed bidirectional image misalignment and distortion caused by the non-ideal movement of the resonant galvanometer and realizing bidirectional high-speed scanning imaging.

[0068] The above are only preferred embodiments of the present application, and only specifically describe the technical principles of the present application. These descriptions are only for explaining the principles of the present application and cannot be interpreted as limiting the scope of protection of the present application in any way. Based on the explanation here, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application, and other specific implementation methods of the present application that can be associated with the technicians in this field without creative work, should be included in the scope of protection of the present application.

Claims

1. A corneal confocal high-speed imaging misalignment correction system, characterized in that: include: A laser, a beam splitter, a scanning galvanometer, a scanning lens, a main image aperture, a tube lens, an objective lens, a pinhole lens, a pinhole, a detector and an imaging control unit, wherein the imaging control unit is electrically connected to the laser, the detector and the scanning galvanometer, wherein: The illumination light beam emitted by the laser is reflected by the beam splitter and then incident on the scanning galvanometer. The illumination light beam scanned by the scanning galvanometer is incident on the scanning lens and then enters the tube lens through the main image plane aperture. The illumination light beam passing through the tube lens is then focused on the cornea through the objective lens. The objective lens collects the light signal from the cornea. The light signal then passes through the tube lens, the main image plane aperture, the scanning lens, the scanning galvanometer, the beam splitter, the pinhole lens in sequence and then is detected by the detector through the pinhole. The detector converts the acquired light signal into an electrical signal and transmits it to the imaging control unit. The imaging control unit receives the electrical signal and reconstructs the scanned image. The imaging control unit controls the scanning galvanometer to perform lateral scanning and longitudinal scanning to realize point scanning imaging of the corneal confocal system, and controls the position of the main image plane aperture during the scanning imaging process to correct the misaligned image.

2. The corneal confocal high-speed imaging misalignment correction system according to claim 1, characterized in that: The imaging control unit drives the scanning galvanometer to scan horizontally to generate a resonance waveform, the displacement and time of which conform to the law of the cosine function, and in one cycle, it can be divided into two scanning parts: the outbound scan and the return scan; The imaging control unit drives the scanning galvanometer to scan longitudinally to generate a galvanometer waveform. When the resonance waveform completes a forward or return scan, its position is switched to the position of the next row.

3. The corneal confocal high-speed imaging misalignment correction system as claimed in claim 2, characterized in that: Part of the values ​​of the data sequence obtained by scanning imaging of the main image plane diaphragm are characteristic intensity values ​​of the main image plane diaphragm, and the specific process is as follows: a) Sampling: For each data sampling, i.e., the scanning galvanometer swings for one cycle, the number of sampling points is N, and the sampling data is {s[n], n=1→N}; b) Segmentation of outbound and return data: obtain the boundary positions n1, n2, n3, n4 of the characteristic intensity values ​​and the ordinary intensity values ​​of the main image plane aperture, then the outbound data is {s[n], n=n1→n2}, and the return data is {s[n], n=n3→n4}. At this time, the return and outbound data are guaranteed by the main image plane aperture to have the range of their imaging area.

4. The corneal confocal high-speed imaging misalignment correction system as claimed in claim 3, characterized in that: The imaging control unit controls the position of the main image plane aperture to correct the misaligned image, which specifically includes the following steps: Perform conventional cosine nonlinear distortion correction on the outbound data and the return data respectively to obtain odd-numbered line and even-numbered line image data; The image data of the odd-numbered lines and the even-numbered lines are combined to form a completed corneal confocal image.

5. The corneal confocal high-speed imaging misalignment correction system according to claim 4, characterized in that: The steps of respectively performing conventional cosine nonlinear distortion correction on the outbound data and the return data to obtain the odd-numbered lines and the even-numbered lines of image data specifically include: Corresponding to the outbound path, which is the odd-numbered row of the image, the sampling point number corresponding to the pixel coordinate x is: pass The rounded value is Then the intensity value corresponding to the pixel coordinate x is Corresponding to the return path, which is the even-numbered row of the image, the sampling point number corresponding to the pixel coordinate x is: pass The rounded value is Then the intensity value corresponding to the pixel coordinate x is Among them: the number of pixels in a row is determined by X max , the pixel value of each row is I l (x),x=1→X max ,l is the line number.

6. The corneal confocal high-speed imaging misalignment correction system according to claim 1, characterized in that: It also includes an objective lens driving unit, which can drive the objective lens to move. The imaging control unit is electrically connected to the objective lens driving unit and is used to control the operation of the objective lens driving unit.

Images