Multiband tunable scanning laser ophthalmoscope fundus imaging optical system and method

Abstract

The application belongs to the technical field of optical imaging system. A multi-band adjustable scanning laser fundus imaging optical system and method are provided. The optical path comprises a wide spectrum light source, a collimating lens, a refractive grating, a focusing lens, an adjustable slit device, a collimator and a light source coupling optical fiber in sequence. The wide spectrum light source provides continuous spectrum. The linear spectrum image is formed on the focal plane by grating dispersion and focusing lens. The adjustable slit device is located on the focal plane. Four independent slit units are controlled by moving the plate and the push rod. One to four target bands can be dynamically intercepted. After the selected wave beams are collimated by the collimator, they are coupled into a single optical fiber for output. Through strict optical design constraints, the application ensures efficient collection and common fiber transmission of multi-band light, and realizes compact structure, flexible and adjustable band and coaxial illumination of multi-modal fundus synchronous imaging.

Description

Technical Field

[0001] This invention relates to the field of optical imaging system technology, and in particular to a multi-band adjustable scanning laser ophthalmoscope fundus imaging optical system and method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In the field of fundus imaging, scanning laser ophthalmoscopes (SLOs) have become an important tool for the clinical diagnosis of retinal diseases due to their advantages such as high contrast, high resolution, and non-invasiveness. Traditional SLO systems typically use a single fixed-wavelength laser as the illumination source, such as 488 nm for observing the retinal nerve fiber layer, 532 nm for enhancing vascular contrast, or 790 nm for penetrating to the deep choroidal structures. With the increasing demand for multimodal fundus information fusion, researchers have gradually introduced multi-band imaging technology, which obtains complementary structural and functional information by selectively responding to fundus tissues with different wavelengths of light. Early implementations often relied on combinations of multiple independent lasers, along with complex optical path switching or beam combining devices, to support multi-wavelength illumination. While such solutions can achieve multi-spectral imaging, the system structure is complex, bulky, and costly, and it is difficult to ensure strict spatial and temporal synchronization of each wavelength, limiting their application in portable or integrated devices.

[0004] Existing SLO systems have significant limitations in achieving multi-band illumination. Using multiple discrete lasers results in large system size and high cost, and the optical axes of each light source are difficult to perfectly align, causing offsets in the illumination areas of different bands and affecting the spatial consistency of multi-band images. While using a filter wheel with a broadband light source can reduce the number of light sources, the band switching speed is slow, making simultaneous multi-band illumination impossible, and only one band is allowed to pass at a time, limiting imaging efficiency and flexibility. Furthermore, current technologies cannot simultaneously output multiple discrete bands in the same illumination path, requiring multiple scans or complex optical path reconstructions for multimodal imaging. These problems result in deficiencies in band configuration flexibility, imaging synchronization, structural compactness, and clinical applicability of current systems, hindering the further promotion and application of multi-band SLO technology. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system and method, enabling simultaneous detection and imaging of SLO (Short-Range Locator) in any 1-4 bands. A broadband light source is first converted into parallel light by a lens, then split by a grating, focusing the light from different bands onto adjustable slits. These adjustable slits control the opening and closing of any 1-4 slits, allowing light from 1-4 target bands to exit and enter a collimator. The light entering the collimator is then coupled into a light source coupling fiber, and finally emitted as the SLO light source.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a multi-band adjustable scanning laser ophthalmoscope fundus imaging optical system.

[0008] A multi-band adjustable scanning laser ophthalmoscope fundus imaging optical system includes a broadband light source, a collimating lens, a grating, a focusing lens, an adjustable slit device, a collimator, and a light source coupling fiber arranged sequentially along the optical path;

[0009] Broadband light sources are used to emit continuous spectrum beams of light;

[0010] A collimating lens is placed on the light-emitting side of a broadband light source to convert the divergent beam emitted by the broadband light source into a parallel beam.

[0011] The grating is a refractive grating, which is set on the exit side of the collimating lens and is used to disperse the parallel beam.

[0012] A focusing lens is positioned on the exit side of the grating to form a spectral image of each wavelength component after dispersion by the grating on its focal plane, which is linearly distributed according to wavelength.

[0013] The adjustable slit device is located at the focal plane of the focusing lens. The adjustable slit device has four independently controllable slit units, which are used to simultaneously capture one to four discrete target wavelengths of light in the spectral image.

[0014] The collimator is located on the output side of the adjustable slit device and is used to receive and collimate the light of each target band passing through the slit unit.

[0015] The light source coupling fiber is set on the output side of the collimator to couple the collimated light of each target wavelength into the same fiber, serving as a multi-band common fiber illumination source output.

[0016] In one implementation of the first aspect of the present invention, the incident angle of the grating is equal to the diffraction angle corresponding to the center wavelength of the broadband light source.

[0017] In one implementation of the first aspect of the present invention, the focal length of the focusing lens, the minimum and maximum wavelengths of the broadband light source, and the widths of two adjacent slits of the grating together determine the center distance between any two adjacent wavelengths in the spectral image on the focal plane.

[0018] In one implementation of the first aspect of the present invention, the center distance between any two adjacent slit units in the adjustable slit device is equal to the center distance between the corresponding two wavelengths on the focal plane, and the center distance is the sum of the slit width and the slit spacing.

[0019] In one implementation of the first aspect of the present invention, the distance between the collimator and the adjustable slit device is not greater than the maximum permissible spacing determined by the angle between the two adjacent target band beams after exiting the adjustable slit device and the normal, and the center distance between them on the focal plane.

[0020] In one implementation of the first aspect of the invention, the size of the collimator is less than or equal to the total lateral divergence width determined by the maximum permissible spacing and the angle between the two adjacent target band beams after exiting the adjustable slit device and the normal.

[0021] In one implementation of the first aspect of the present invention, the adjustable slit device includes a movable plate and four push rods, each push rod being connected to a stop block for blocking the corresponding slit unit. By driving the push rod, the stop block is moved upward to release light from the slit.

[0022] Secondly, the present invention provides a multi-band adjustable fundus imaging method.

[0023] A multi-band adjustable fundus imaging method, utilizing the multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system of the first aspect of this invention, includes the following processes:

[0024] Turn on the broadband light source to emit a continuous spectrum beam of light;

[0025] The light emitted from the broadband light source is converted into a parallel beam by a collimating lens and then incident on the grating.

[0026] Dispersion of parallel light beams using a grating;

[0027] By using a focusing lens, the dispersed wavelength components are formed into a spectral image on its focal plane that is linearly distributed according to wavelength;

[0028] The adjustable slit device opens several slit units to simultaneously capture one to four discrete target wavelengths of light in the spectral image.

[0029] The light of each target band passing through the slit unit is collimated by a collimator and then coupled into the same light source coupling fiber, which is used as a common fiber multi-band illumination light for fundus scanning imaging.

[0030] In one implementation of the second aspect of the present invention, before the adjustable slit device opens the slit unit, the position of each target wavelength on the focal plane is calculated based on the wavelength value of the target band, the dispersion relationship of the grating and the focal length of the focusing lens, and the moving plate of the adjustable slit device is moved to the target slit position accordingly.

[0031] In one implementation of the second aspect of the present invention, the step of controlling the adjustable slit device to open the slit unit includes: driving the movable plate of the adjustable slit device to move to a region containing all target band positions, and then driving the push rod corresponding to each target band to move the block blocking the slit unit upward to release the light source in the slit.

[0032] In one implementation of the second aspect of the present invention, the target band includes any one to four combinations of 488 nm, 532 nm, 633 nm and 790 nm.

[0033] In one implementation of the second aspect of the present invention, multi-band illumination light coupled into the light source and the coupling fiber is introduced into the scanning module of the scanning laser ophthalmoscope to perform synchronous scanning of the fundus; the reflected light from the fundus is received, and the reflected light of different bands is separated into corresponding detectors by the beam splitting module to generate fundus images of each band.

[0034] In one implementation of the second aspect of the present invention, the beam splitting cutoff wavelength of each beam splitting element in the beam splitting module is set according to the wavelength interval between the selected target bands, so as to achieve effective isolation of light in each band.

[0035] In one implementation of the second aspect of the present invention, before coupling multi-band light into the light source coupled optical fiber, it is verified whether the actual distance between the collimator and the adjustable slit device satisfies the maximum allowable distance condition determined by the exit angle of adjacent target band light and the focal plane spacing.

[0036] In one implementation of the second aspect of the present invention, it is supported to dynamically switch different target band combinations during a single inspection, and the switching operation is completed by reconfiguring the action state of the push rod in the adjustable slit device.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] This invention innovatively proposes a multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system, which can achieve a complete conversion from a single broadband light source to multiple discrete target band co-fiber outputs within a highly integrated optical path architecture. Through the synergistic effect of a refractive grating and a focusing lens, the system forms a clear linear spectral image on the focal plane and utilizes an adjustable slit device located on this focal plane for precise spatial wave selection, fundamentally avoiding the problems of system complexity, high cost, and large size associated with traditional multi-laser solutions. Since all selected bands are ultimately coupled into the same light source coupling fiber, complete spatial overlap of the illumination light of each wavelength is ensured, providing a physical basis for subsequent synchronous scanning and high-precision multimodal image registration.

[0039] This invention precisely sets the incident angle of the grating to the diffraction angle of the center wavelength, enabling the system to operate in self-collimation mode. This not only simplifies the overall optical path layout, making the system more compact, but also significantly improves the stability of the optical path. In this configuration, the center wavelength light returns along its original path, effectively reducing aberrations and energy losses introduced by optical path asymmetry. Simultaneously, the focal length of the focusing lens and the grating parameters jointly determine the precise position of each wavelength in the spectral image, allowing the slit units in the adjustable slit device to be precisely arranged according to the preset target wavelength. This deterministic design based on physical principles ensures the accuracy and repeatability of band selection, laying a solid foundation for reliable switching between different imaging modes (such as nerve fiber layer, vascular, or choroidal imaging) in clinical applications.

[0040] The distance between the collimator and the adjustable slit device, as well as the dimensions of the collimator itself, are subject to strict optical constraints stemming from an in-depth analysis of the divergence characteristics of multi-band beams. By limiting the distance to a maximum permissible value determined by the angle and spacing between adjacent bands, and setting the collimator size to not exceed the corresponding total lateral divergence width, the system ensures that all target band light emitted from different slits can be effectively captured by the collimator. This design principle effectively prevents energy loss in edge bands, ensuring that the illumination light of each band has sufficiently high energy utilization and good beam quality before entering the coupling fiber, which is a key prerequisite for achieving efficient co-fiber coupling.

[0041] The adjustable slit device of this invention employs a mechanical structure linking a moving plate and a push rod. By driving the push rod to move the stop upward, the desired wavelength of light is emitted. This design achieves precise and reliable control of four independent slit units. Operators can dynamically select one to four target wavelengths in any combination according to diagnostic needs. The entire process involves only minor movements of internal mechanical components, without the need to replace any external light source or optical elements. This high degree of flexibility allows a single device to quickly adapt to various clinical examination scenarios, seamlessly switching from conventional structural imaging to functional or metabolic imaging, greatly enhancing the practical value and diagnostic efficiency of the device.

[0042] The multi-band imaging method of this invention can simultaneously acquire fundus images of multiple bands in a single scan. Since all bands originate from the same broadband light source and are output through the same optical fiber, its temporal synchronization and spatial consistency are naturally superior to discrete light source solutions. This not only significantly shortens examination time and reduces the burden on patients, but more importantly, it completely eliminates the problem of multi-frame image misalignment caused by micro-movements of the eyeball or optical axis deviations of multiple light sources. The resulting multimodal images have perfect pixel-level alignment, providing doctors with a high-quality, high-reliability information fusion platform for comprehensive analysis, early lesion screening, and accurate diagnosis.

[0043] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0044] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0045] Figure 1 A schematic diagram of a multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system provided as an exemplary embodiment of the present invention;

[0046] Figure 2 A diffraction diagram of a double-slit grating provided as an exemplary embodiment of the present invention;

[0047] Figure 3 A focusing schematic diagram of a focusing lens provided as an exemplary embodiment of the present invention;

[0048] Figure 4 A schematic diagram of the slit width provided for an exemplary embodiment of the present invention;

[0049] Figure 5 A schematic diagram of the optical path of a focusing lens provided as an exemplary embodiment of the present invention;

[0050] Figure 6 Slit diffraction diagram provided for an exemplary embodiment of the present invention Figure 1 ;

[0051] Figure 7 Slit diffraction diagram provided for an exemplary embodiment of the present invention Figure 2 ;

[0052] Figure 8 A schematic diagram of the projection of the emitted light ray provided as an exemplary embodiment of the present invention;

[0053] Figure 9A schematic diagram of an adjustable slit device provided as an exemplary embodiment of the present invention;

[0054] Figure 10 A schematic diagram of a multi-band adjustable fundus imaging method provided as an exemplary embodiment of the present invention;

[0055] Among them, 1. Broadband light source; 2. Collimating lens; 3. Grating; 4. Focusing lens; 5. Adjustable slit device; 6. Collimator; 7. Light source coupling fiber; 8. Optical output port; 9. First lens; 10. Second lens; 11. First photodetector; 12. Second photodetector; 13. Third photodetector; 14. Fourth photodetector; 15. First beam splitter; 16. Second beam splitter; 17. Third beam splitter; 18. Fourth beam splitter; 19. X-axis galvanometer; 20. Y-axis galvanometer; 21. Third lens; 22. Fourth lens; 23. Eyeball; 25. First motor; 26. Second motor. Detailed Implementation

[0056] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0057] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0058] Preferred embodiments of the present invention will now be described in detail by way of example only, with reference to the accompanying drawings. It should be emphasized that the specific structures and parameters described below are merely illustrative and should not be construed as limiting the scope of protection of the present invention. The present invention aims to solve the core problems faced by existing scanning laser ophthalmoscope (SLO) systems in achieving multi-band illumination, such as high cost, large size, poor synchronization, and insufficient flexibility. To this end, the present invention proposes an innovative optical architecture. The core idea of ​​this architecture is to utilize a broadband light source to flexibly extract and synchronously output multiple discrete target bands from the continuous spectrum through a series of steps including dispersion, focusing spectral formation, spatial wave selection, and co-fiber coupling, thereby providing an efficient, compact, and dynamically configurable multi-band illumination solution for SLO.

[0059] like Figure 1 As shown, the multi-band adjustable SLO fundus imaging optical system of the present invention comprises a broadband light source 1, a collimating lens 2, a grating 3, a focusing lens 4, an adjustable slit device 5, a collimator 6, and a light source coupling fiber 7 arranged sequentially along a single optical path. These components together form a complete and functionally defined optical path chain, in which the position or parameter of any component is closely related to the other components, jointly determining the final performance of the system. Figure 1In this process, the core optical path principle begins with the continuous spectral diverging light emitted by the broadband light source 1. This beam is converted into parallel light by the collimating lens 2 and then incident on the refractive grating 3. The grating's dispersion characteristics are used to separate light of different wavelengths in space. The separated beams are then converged by the focusing lens 4, forming a focused position with a linear wavelength distribution at its focal plane. The adjustable slit device 5 located at this focal plane controls the raising and lowering of the stop block by a motor-driven moving plate and push rod to precisely open one to four independent slit units, thereby dynamically intercepting the desired specific target wavelength band from the focal plane. The selected multi-band light then enters the collimator 6 for re-collimation and is coupled into the same light source coupling fiber 7 as a common fiber illumination source output (output through the light output port 8), ensuring that the light of each wavelength band is completely overlapped in space and scans the fundus synchronously. When the illumination light is reflected back by the eyeball 23, the beam splitting module at the system receiver starts working. The first beam splitter 15, according to a preset cutoff wavelength, initially separates the returned polychromatic reflected light, reflecting short-wavelength light to the first photodetector 11 to generate an image of the superficial retinal structure in that wavelength band, while simultaneously transmitting the remaining longer wavelengths. The transmitted light continues to propagate to the second beam splitter 16, which further splits the light according to the next wavelength interval, reflecting specific medium-short wavelengths to the second photodetector 12 to enhance vascular contrast imaging, while transmitting the remaining long-wavelength light. Subsequently, the third beam splitter 1... The remaining light beam undergoes a third separation, reflecting specific mid-to-long wavelength light to the third photodetector 13 to obtain information about the middle layer of tissue, while simultaneously transmitting the longest wavelength light. Finally, the remaining long wavelength light is either directly incident on or guided by the fourth beam splitter 18 to the fourth photodetector 14, which is responsible for receiving the near-infrared light with the strongest penetrating power to image deep structures such as the choroid. Through the cascaded filtering and routing of these four beam splitters, and the parallel synchronous acquisition of the four photodetectors, the system ultimately achieves the simultaneous acquisition of four highly registered multimodal fundus images with different depths and functional characteristics in a single scan. A first lens 9 and a second lens 10 are sequentially arranged in the optical path between the light output port 8 and the fourth beam splitter 18. An X-axis galvanometer 19, a Y-axis galvanometer 20, a third lens 21, and a fourth lens 22 are sequentially arranged in the optical path between the first beam splitter 15 and the eyeball 23.

[0060] More specifically, firstly, the broadband light source 1 serves as the light energy starting point for the entire system, providing a continuous spectrum covering the required wavelength range. In a typical embodiment of the invention, the output spectrum of the broadband light source 1 covers the 400-800 nanometer band. This wavelength range is not chosen arbitrarily, but is determined based on the absorption, scattering, and autofluorescence characteristics of fundus tissues for different wavelengths of light. For example, short wavelengths (e.g., 488 nm) have good imaging effects on the superficial nerve fiber layer of the retina; medium wavelengths (e.g., 532 nm) are strongly absorbed by hemoglobin, thereby enhancing the contrast of blood vessels; while long wavelengths (e.g., 790 nm) have stronger penetrating power and can be used to observe deep structures such as the choroid. The broadband light source 1 can be a supercontinuum laser, which can generate an ultra-wideband, high-brightness, and highly coherent continuous spectrum from visible light to near-infrared within a miniaturized package, making it very suitable as the light source basis for the invention. The beam emitted by the broadband light source 1 is usually divergent, and collimation processing is necessary to enable it to work effectively with subsequent dispersive elements.

[0061] Therefore, collimating lens 2 is located immediately following the light-emitting side of broadband light source 1. The main function of collimating lens 2 is to convert the divergent beam output from broadband light source 1 into a parallel beam. This step is crucial because only when a parallel beam is incident on grating 3 can the diffraction angles of each wavelength component after dispersion be guaranteed to be clear, stable, and accurately calculable. If the incident light is divergent, different rays of the same wavelength will be incident on grating 3 at slightly different angles, resulting in a certain degree of angular broadening in the diffracted light. This will severely degrade the resolution of the spectral image subsequently formed on the focal plane, making it difficult to clearly separate adjacent bands, and thus affecting the wave selection accuracy of adjustable slit device 5. Therefore, the focal length and installation position of collimating lens 2 need to be precisely matched according to the light-emitting characteristics and light-emitting aperture size of broadband light source 1 to ensure that the emitted beam has a sufficiently high parallelism.

[0062] After being processed by collimating lens 2, a high-quality parallel beam is then incident on grating 3. Grating 3 is located on the exit side of collimating lens 2 and is the core dispersive element for wavelength separation in this system. In a preferred embodiment of the invention, grating 3 is a refractive grating. The basic working principle of grating 3 is to utilize its periodic microstructure to produce different diffraction effects on light of different wavelengths. Specifically, when a beam of parallel light containing multiple wavelengths is incident on grating 3, light of different wavelengths is reflected (or transmitted) in different directions, thereby achieving spatial dispersion separation.

[0063] like Figure 2As shown, this is a grating with only two slits. The incident beam has been collimated, so all rays in the beam are parallel to each other. If we only consider the two rays passing through the two slits (red arrows), the path difference between the two rays is... (Length of blue line):

[0064] (1);

[0065] Make the path difference equivalent to a wavelength. If constructive interference occurs between two rays, then:

[0066] (2);

[0067] The diffraction angle is then:

[0068] (3);

[0069] This invention uses a refractive grating such that the incident angle of all light is equal to the diffraction angle of the center wavelength of the light source, then:

[0070] (4);

[0071] (5);

[0072] but:

[0073] (6);

[0074] in, Represents the path difference between two adjacent light rays ( Figure 2 (The blue line is long). This represents the width of two adjacent slits in the grating; Represents the angle between any incident light and the normal to the slit plane; Represents the angle between any diffracted light and the normal to the slit plane; The angle between the incident light of the center wavelength and the normal to the slit plane; The angle between the diffracted light of the center wavelength and the normal to the slit plane; This represents the wavelength of the light incident on the center of the slit; It represents the wavelength of any light emitted by the light source.

[0075] like Figure 3 As shown, when light rays pass through the focusing lens at the minimum and maximum angles, the adjacent distance L between the two rays at the exit slit is:

[0076] (7);

[0077] Then the distance between any two waves at the exit slit for:

[0078] (8);

[0079] (9)

[0080] in, This represents the focal length of the focusing lens; The angle between the diffracted light representing the maximum wavelength and the normal to the slit plane; The angle between the diffracted light representing the smallest wavelength and the normal to the slit plane; The maximum wavelength representing a broadband light source; The smallest wavelength representing a broadband light source; Representing the The wavelength of each target band; Representing the The wavelength of each target band; Representing the Target wavelength The diffraction angle after grating dispersion; Representing the Target wavelength The diffraction angle after grating dispersion.

[0081] like Figure 4 As shown, let the slit width be... The slit spacing is The center distance between the two slits is The design standard for adjacent slits is:

[0082] (10);

[0083] like Figure 5 As shown, let the focusing lens be of radius r. If the circle is given and the diameter of the grating is D, then the projection line of the focusing lens is 2. The projected line of the grating is .

[0084] Let the vertical distances from the edges of the two gratings to the lens be respectively Then the distance between the two maximum and minimum wavelengths emitted from the edges of the two gratings is:

[0085] (11);

[0086] (12);

[0087] (13);

[0088] At that time, the lens receives exactly all the light rays refracted by the grating, among which, This represents the distance between the center wavelength light and the minimum wavelength light after they exit from the top of the grating and are projected onto the focusing lens. This represents the distance on the focusing lens after the center wavelength light and the maximum wavelength light are emitted from the bottom of the grating; This represents the distance the center wavelength light travels on the focusing lens after exiting from both ends of the grating.

[0089] Let from The angle between any emitted ray and the normal on the plane of the light exiting the focusing lens is... The distance between the light ray and the center wavelength on the transmission slit is... ,like Figure 6 As shown.

[0090] (14);

[0091] (15);

[0092] (16);

[0093] (17);

[0094] (18)

[0095] (19);

[0096] (20)

[0097] (twenty one)

[0098] (twenty two)

[0099] (twenty three);

[0100] (twenty four)

[0101] (25);

[0102] in, Represents the target wavelength The distance from the center wavelength on the slit plane; Represents the included angle; , and Both represent straight-line distances; This represents the projected length from the center of the grating to the bottom of the grating; The tangent value representing the difference between the diffraction angle and the incident angle; Represents a triangle exist The interior angle of the point.

[0103] Let from Any ray of light emitted from the focusing lens makes an angle of θ with the normal on the grating. ,like Figure 7 As shown.

[0104] (26);

[0105] (27);

[0106] (28);

[0107] (29);

[0108] in, This represents the total lateral offset length of the light rays emitted from the top of the grating. and Both represent linear distances.

[0109] Assume two adjacent bands ,

[0110] from from The angles between the light emitted from the grating and the normal at the slit are respectively... , When two light rays intersect, the projections of the outgoing light rays in the x-direction are respectively , The projection along the y-direction is H, such as Figure 8 As shown:

[0111] :

[0112] (30);

[0113] (31);

[0114] (32);

[0115] (33);

[0116] Similarly, it can be calculated that, Intersection distance :

[0117] Pick:

[0118] (34);

[0119] The maximum distance between the collimator and the slit is H.

[0120] When H is chosen, the divergence width R of this wavelength is:

[0121] (35);

[0122] The maximum size of the collimating lens is R.

[0123] Once the various dimensional parameters are calculated based on the target light source band requirements and the above formulas, the four push rods can be calculated and adjusted to any target band slit using the above formulas. When the system starts working, as... Figure 8 As shown, the motor moves the moving plate to the target slit, and then moves the push rod to move the block blocking the slit upward, releasing the light source in the slit. The broadband light source light is split by the grating, and after the slit selects the light, it is collimated and emitted by 1 to 4 beams, and then coupled into a bundle of optical fibers to be emitted as the SLO light source.

[0124] More specifically, such as Figure 10 As shown, this implementation proposes a multi-band adjustable fundus imaging method, utilizing the aforementioned multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system, including the following processes:

[0125] S1001: Turn on the broadband light source to emit a continuous spectrum beam;

[0126] S1002: Light is converted into a parallel beam by a collimating lens and then incident on the grating;

[0127] S1003: Dispersion of parallel beams using a grating;

[0128] S1004: By using a focusing lens, the dispersed wavelength components are formed on the focal plane to form a spectral image that is linearly distributed according to wavelength;

[0129] S1005: Controls the opening of several slit units in the adjustable slit device to simultaneously capture one to four discrete target wavelengths of light in the spectral image;

[0130] S1006: The light of each target band passing through the slit unit is collimated by a collimator and then coupled into the same light source coupling fiber to serve as a common fiber multi-band illumination light for fundus scanning imaging.

[0131] like Figure 9 As shown, the working process is illustrated using the first motor 25 and the second motor 26 as an example. Before operation, the push rods of both motors are extended to 0. During operation, the push rod of the second motor 26 extends, and the slider moves along... The directional slide moves to the target slit, then the push rod of the first motor 25 extends, and the baffle moves along... The directional slot moves toward the stop block, the stop block is lifted by the slider, and the light of the target wavelength is emitted. The operation of the other motors and sliders is the same as described above.

[0132] Before controlling the adjustable slit device to open the slit unit, the position of each target wavelength on the focal plane is calculated based on the wavelength value of the target band, the dispersion relationship of the grating, and the focal length of the focusing lens. Based on this, the moving plate of the adjustable slit device is moved to the target slit position. The steps for controlling the adjustable slit device to open the slit unit include: driving the moving plate of the adjustable slit device to move to the area containing the positions of all target bands, and then driving the push rods corresponding to each target band to move the blocks blocking the slit unit upwards, releasing the light source from the slit. Multi-band illumination light coupled into the light source coupling fiber is introduced into the scanning module of the scanning laser ophthalmoscope for synchronous scanning of the fundus; reflected light from the fundus is received, and the reflected light of different bands is separated into corresponding detectors by the beam splitting module to generate fundus images of each band. The beam splitting cutoff wavelength of each beam splitting element in the beam splitting module is set according to the wavelength interval between the selected target bands to achieve effective isolation of light in each band. Before coupling multi-band light into the light source coupling fiber, it is verified whether the actual distance between the collimator and the adjustable slit device meets the maximum allowable distance condition determined by the exit angle of adjacent target band light and the focal plane distance. This invention supports dynamic switching of different target band combinations during a single inspection. The switching operation is completed by reconfiguring the action state of the push rod in the adjustable slit device.

[0133] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system, characterized in that, It includes a broadband light source, a collimating lens, a grating, a focusing lens, an adjustable slit device, a collimator, and a light source coupling fiber arranged sequentially along the optical path; The broadband light source is used to emit a continuous spectrum beam of light; The collimating lens is disposed on the light-emitting side of the broadband light source and is used to convert the divergent beam emitted by the broadband light source into a parallel beam. The grating is a refractive grating, which is set on the exit side of the collimating lens and is used to disperse the parallel beam. The focusing lens is disposed on the exit side of the grating and is used to form a spectral image with a linear wavelength distribution on the focal plane of the focusing lens for each wavelength component after dispersion by the grating. The adjustable slit device is located at the focal plane of the focusing lens. The adjustable slit device has four independently controllable slit units, which are used to simultaneously capture one to four discrete target wavelengths of light in the spectral image. The collimator is located on the output side of the adjustable slit device and is used to receive the target wavelength light passing through the slit unit and collimate the target wavelength light. The light source coupling fiber is located on the output side of the collimator and is used to couple the collimated target wavelength light into the same fiber to serve as a multi-band common fiber illumination source output.

2. The multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system as described in claim 1, characterized in that, The incident angle of the grating is equal to the diffraction angle corresponding to the center wavelength of the broadband light source.

3. The multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system as described in claim 1, characterized in that, The focal length of the focusing lens, the minimum and maximum wavelengths of the broadband light source, and the widths of two adjacent slits of the grating together determine the center distance between any two adjacent wavelengths in the spectral image on the focal plane.

4. The multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system as described in claim 1, characterized in that, The center distance between any two adjacent slit units in the adjustable slit device is equal to the center distance between the corresponding two wavelengths on the focal plane, and the center distance is the sum of the slit width and the slit spacing.

5. The multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system as described in claim 1, characterized in that, The distance between the collimator and the adjustable slit device is no greater than the maximum permissible spacing determined by the angle between the two adjacent target wavelength beams after exiting the adjustable slit device and the normal to the exit surface of the adjustable slit device, and the center distance between the two adjacent target wavelength beams on the focal plane of the focusing lens.

6. The multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system as described in claim 5, characterized in that, The size of the collimator is less than or equal to the total lateral divergence width determined by the maximum permissible spacing and the angle between the two adjacent target band beams after exiting the adjustable slit device and the normal.

7. The multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system as described in claim 1, characterized in that, The adjustable slit device includes a movable plate and four push rods. Each push rod is connected to a stop block for blocking the corresponding slit unit. By driving the push rod, the stop block is moved upward to release the light in the slit.

8. A multi-band adjustable fundus imaging method, characterized in that, The multi-band adjustable scanning laser ophthalmoscopy fundus imaging optical system according to any one of claims 1-7 includes the following process: Turn on the broadband light source to emit a continuous spectrum beam of light; The light is converted into a parallel beam by a collimating lens and then incident on the grating. Dispersion of parallel light beams using a grating; By using a focusing lens, the dispersed wavelength components are formed into a spectral image on its focal plane that is linearly distributed according to wavelength; The adjustable slit device opens several slit units to simultaneously capture one to four discrete target wavelengths of light in the spectral image. The light of each target band passing through the slit unit is collimated by a collimator and then coupled into the same light source coupling fiber, which is used as a common fiber multi-band illumination light for fundus scanning imaging.

9. The multi-band adjustable fundus imaging method as described in claim 8, characterized in that, Before the adjustable slit device opens the slit unit, the position of each target wavelength on the focal plane of the focusing lens is calculated based on the wavelength value of the target band, the dispersion relationship of the grating, and the focal length of the focusing lens. Based on this, the moving plate of the adjustable slit device is moved to the target slit position.

10. The multi-band adjustable fundus imaging method as described in claim 8, characterized in that, The steps for controlling the adjustable slit device to open the slit unit include: driving the movable plate of the adjustable slit device to move to the area containing all target band positions, and then driving the push rods corresponding to each target band to move the block blocking the slit unit upward, thereby releasing the light source in the slit.

11. The multi-band adjustable fundus imaging method as described in claim 8, characterized in that, Multi-band illumination light coupled into the light source and the coupling fiber is introduced into the scanning module of the scanning laser ophthalmoscope to perform synchronous scanning of the fundus; the reflected light from the fundus is received, and the reflected light of different bands is separated into corresponding detectors by the beam splitting module to generate fundus images of each band.

12. The multi-band adjustable fundus imaging method as described in claim 11, characterized in that, The beam splitting cutoff wavelength of each beam splitting element in the beam splitting module is set according to the wavelength interval between the selected target bands in order to achieve effective isolation of light in each band.

13. The multi-band adjustable fundus imaging method as described in claim 8, characterized in that, Before coupling multi-band light into the light source coupled with the optical fiber, verify whether the actual distance between the collimator and the adjustable slit device meets the maximum allowable distance condition determined by the exit angle of adjacent target band light and the focal plane spacing of the focusing lens.

14. The multi-band adjustable fundus imaging method as described in claim 8, characterized in that, It supports dynamic switching of different target band combinations during a single inspection. The switching operation is completed by reconfiguring the action state of the push rod in the adjustable slit device.

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