Light-trap device for suppressing stray light and biomedical fluorescence imaging system

Abstract

The application provides a light trap device for inhibiting stray light and a biomedical fluorescence imaging system, relates to the technical field of biomedical fluorescence imaging, and the device comprises a light trap body, an incident port is arranged on one side of a light absorption inner cavity of the light trap body, a light absorption layer is arranged on an inner wall of the light absorption inner cavity, a light splitting structure is arranged in the light absorption inner cavity in an inclined manner, and the light absorption inner cavity is sequentially divided into a first light absorption cavity and a second light absorption cavity along a central optical axis extension direction of the stray light; a plurality of light transmission holes are arranged on the light splitting structure, the first light absorption cavity is connected with the second light absorption cavity in a communication mode through the light transmission holes; when the stray light enters the first light absorption cavity through the incident port, part of the stray light is incident to the light splitting structure and is attenuated through multiple reflections in the first light absorption cavity; the other part of the stray light enters the second light absorption cavity through the light transmission hole and is attenuated through multiple reflections in the second light absorption cavity; the stray light is spatially shunted and independently attenuated through the light splitting structure, and the probability of the stray light entering an imaging light path is inhibited from the source.

Description

Technical Field

[0001] This application generally relates to the field of biomedical fluorescence imaging technology, and specifically to a light trapping device and a biomedical fluorescence imaging system for suppressing stray light. Background Technology

[0002] Fluorescence imaging is a core detection and imaging technique in the biomedical field. Its basic principle is to use excitation light of a specific wavelength to illuminate fluorescently labeled biological samples, causing the fluorescent dyes in the samples to emit fluorescence signals with longer wavelengths. Qualitative, quantitative, and localization analysis of the biological samples is achieved by collecting these fluorescence signals. Compared to traditional mercury lamps, xenon lamps, and lasers, LED light sources have become the mainstream excitation source for miniaturized and portable biomedical fluorescence imaging devices due to their advantages such as low cost, small size, low power consumption, wide range of selectable wavelengths, and long lifespan. However, the light intensity of LED excitation light is typically more than six orders of magnitude higher than the weak fluorescence signal generated by the biological sample. Because LED light sources have a large divergence angle, and filters are extremely ineffective at filtering large-angle incident light, stray LED excitation light that does not participate in the excitation of the fluorescent sample easily gets mixed into the imaging optical path, severely overwhelming the fluorescence signal. This leads to a significant decrease in the imaging signal-to-noise ratio, insufficient image contrast, and even the inability to identify weak fluorescence signals in the sample. This directly limits the detection sensitivity and imaging quality of fluorescence imaging.

[0003] To address the aforementioned issues, one existing approach involves using a filtering system comprised of an excitation filter, a dichroic mirror, and an emission filter for spectral isolation. However, the cutoff depth of conventional filters is only OD4~OD6, which still results in unavoidable light leakage for strongly excited stray light, and high-precision filters are also expensive. Another approach employs traditional light trap structures, such as conical light traps, right-angle reflection light traps, and honeycomb light traps. These structures are mostly single-cavity designs with single or limited reflection and absorption, resulting in low absorption efficiency. Some stray light will still be reflected back to the imaging optical path via the mirror, making it impossible to completely attenuate stray light. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a light trapping device and a biomedical fluorescence imaging system for suppressing stray light that can effectively improve the stray light attenuation rate.

[0005] In a first aspect, this application provides a light trapping device for suppressing stray light, comprising: The light trap body has a light-absorbing inner cavity, and an entrance is provided on one side of the light-absorbing inner cavity to receive stray light generated when the excitation light propagates; the inner wall of the light-absorbing inner cavity is provided with a light-absorbing layer to attenuate the energy of the stray light projected thereon. A beam-splitting structure is inclinedly disposed in the light-absorbing cavity, which is used to divide the light-absorbing cavity into a first light-absorbing cavity and a second light-absorbing cavity sequentially along the central optical axis of stray light; the beam-splitting structure is provided with a plurality of light-transmitting holes, and the first light-absorbing cavity is connected to the second light-absorbing cavity through the light-transmitting holes. When the stray light enters the first light-absorbing cavity through the entrance port, a portion of the stray light is incident on the beam-splitting structure and attenuated by multiple reflections within the first light-absorbing cavity; the other portion of the stray light enters the second light-absorbing cavity through the light-transmitting hole and attenuates by multiple reflections within the second light-absorbing cavity.

[0006] According to the technical solution provided in this application, the beam-splitting structure includes: An inclined beam-splitting baffle forms a first angle with the central optical axis of stray light incident through the entrance port, and the opening of the first angle faces the second light-absorbing cavity; the light-absorbing layer is provided on both outer surfaces of the beam-splitting baffle.

[0007] According to the technical solution provided in this application, the light-absorbing layer includes: A micro-particle rough structure is disposed on the inner wall of the light-absorbing cavity and on the surface of the beam-splitting baffle. A black light-absorbing coating layer is disposed on the side of the micro-particle rough structure away from the inner wall of the light-absorbing cavity or the surface of the beam-splitting baffle.

[0008] According to the technical solution provided in this application, the black light-absorbing coating layer is a black anodized layer or a matte black light-absorbing coating layer; the angle range of the first included angle is 40°~50°.

[0009] According to the technical solution provided in this application, the light-transmitting holes are arranged in a regular matrix, and the light-transmitting holes are circular light-transmitting holes, with a total aperture ratio of 40% to 60% for multiple circular light-transmitting holes; the light trap body is a metal box structure.

[0010] According to the technical solution provided in this application, the cross-sectional area of ​​the entrance is greater than or equal to the spot area of ​​the stray light on the plane where the entrance is located.

[0011] According to the technical solution provided in this application, the beam-splitting baffle is welded to the inner wall of the light-absorbing cavity.

[0012] According to the technical solution provided in this application, the outer surface of the light trap body is provided with an installation structure for connecting to a fluorescence imaging system.

[0013] Secondly, this application provides a biomedical fluorescence imaging system, comprising: An LED excitation source is used to generate excitation light for exciting fluorescent samples; An imaging optical path is provided, wherein the incident end of the imaging optical path and the light-emitting end of the LED excitation light source are respectively arranged. The imaging optical path is used to guide the excitation light to the fluorescent sample and collect the fluorescence signal emitted by the fluorescent sample after it is excited. The aforementioned optical trapping device for suppressing stray light has its inlet facing the location where stray light is generated in the imaging optical path. The optical trapping device is used to collect and attenuate stray light that does not participate in the excitation of the fluorescent sample, thereby suppressing the stray light from entering the imaging optical path. A fluorescence imaging structure is disposed at the emitting end of the imaging optical path for receiving the fluorescence signal and imaging it.

[0014] According to the technical solution provided in this application, the imaging optical path includes: A microscope objective is disposed between a stage for supporting the fluorescent sample and the fluorescence imaging structure. The microscope objective is used to focus the excitation light onto the fluorescent sample and collect the fluorescence signal emitted by the fluorescent sample after excitation. A filter structure is disposed between the microscope objective and the fluorescence imaging structure to reflect the excitation light from the LED excitation source to the microscope objective and transmit the fluorescence signal collected by the microscope objective to the fluorescence imaging structure; the entrance of the light trapping device is correspondingly disposed with the filter structure to collect stray light that has passed through the filter structure but has not been reflected to the fluorescence sample.

[0015] As can be seen from the above technical solution, this application has at least the following beneficial effects: This application provides a light trapping device for suppressing stray light, comprising: a light trapping body having a light-absorbing cavity, an entrance port on one side of the light-absorbing cavity for receiving stray light generated during the propagation of excitation light; a light-absorbing layer on the inner wall of the light-absorbing cavity for attenuating the energy of the stray light projected thereon; a beam-splitting structure, the beam-splitting structure being obliquely disposed in the light-absorbing cavity for dividing the light-absorbing cavity sequentially into a first light-absorbing cavity and a second light-absorbing cavity along the central optical axis of the stray light; a plurality of light-transmitting holes being formed on the beam-splitting structure, the first light-absorbing cavity being connected to the second light-absorbing cavity through the light-transmitting holes; when stray light enters the first light-absorbing cavity through the entrance port, a portion of the stray light is incident on the beam-splitting structure and attenuated by multiple reflections within the first light-absorbing cavity; another portion of the stray light enters the second light-absorbing cavity through the light-transmitting holes and is attenuated by multiple reflections within the second light-absorbing cavity.

[0016] This application utilizes a beam-splitting structure tilted within a light-absorbing cavity, dividing the cavity sequentially into a first and a second light-absorbing cavity along the stray light propagation direction. Multiple light-passing holes are formed on the beam-splitting structure to connect the two cavities. When stray light enters the first light-absorbing cavity through the entrance port, the area of ​​the beam-splitting structure, excluding the light-passing holes, reflects a portion of the stray light to the light-absorbing layer on the inner wall of the light-absorbing cavity. This portion of the stray light is attenuated by multiple reflections within the first light-absorbing cavity, thus preventing the stray light from directly returning along its original path. Simultaneously, the light-passing holes on the beam-splitting structure allow another portion of stray light to enter the second light-absorbing cavity, where it undergoes multiple reflections and attenuation with the corresponding light-absorbing layer within the relatively enclosed second light-absorbing cavity. This minimizes the probability of stray light passing through the beam-splitting structure returning to the entrance port. By spatially splitting and independently attenuating the stray light through the beam-splitting structure, the stray light is effectively confined within the light trap body and gradually attenuated, suppressing stray light from entering the imaging optical path at its source, thereby improving the signal-to-noise ratio of fluorescence imaging. Attached Figure Description

[0017] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0018] Figure 1 This is a structural diagram of a light trap device used to suppress stray light.

[0019] Figure 2 This is a structural diagram of the beam-splitting baffle.

[0020] Figure 3 This is a structural diagram of a biomedical fluorescence imaging system.

[0021] The following are the labels in the diagram: 1. Light trap body; 2. Inlet; 3. Light passage; 4. Beam splitter; 5. LED excitation source; 6. Fluorescent imaging structure; 7. Microscope objective; 8. Filter structure; 9. Fixing stage; 10. Mounting stage; 11. Main unit casing; 12. Fluorescent sample. Detailed Implementation

[0022] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] To ensure clarity and conciseness in the description of the following embodiments, a brief introduction to the related technologies is given first: In LED-excited biomedical fluorescence imaging systems, the excitation light generated by the LED excitation source is reflected by a filter device and then illuminates the fluorescent sample, causing the sample to emit a fluorescence signal. This fluorescence signal is collected by a microscope objective and transmitted through the filter device before being received and imaged by the fluorescence imaging structure. However, because the filter device cannot achieve 100% reflection cutoff, some LED excitation light will pass through the filter device without participating in the excitation of the fluorescent sample. If this stray light directly enters the imaging optical path, it will severely overwhelm the weak fluorescence signal, resulting in a decreased imaging signal-to-noise ratio and insufficient contrast.

[0025] In view of this, this application utilizes a beam-splitting structure tilted within the light-absorbing cavity, dividing the light-absorbing cavity sequentially into a first light-absorbing cavity and a second light-absorbing cavity along the stray light propagation direction. Multiple light-passing holes are formed on the beam-splitting structure to connect the two light-absorbing cavities. When stray light enters the first light-absorbing cavity through the entrance port, the area of ​​the beam-splitting structure, excluding the light-passing holes, reflects a portion of the stray light to the light-absorbing layer on the inner wall of the light-absorbing cavity. This causes the stray light to be attenuated by multiple reflections within the first light-absorbing cavity, thereby preventing the stray light from directly returning along its original path. At the same time, the light-passing hole on the beam-splitting structure allows another part of the stray light to enter the second light-absorbing cavity. This stray light undergoes multiple reflections and attenuation with the corresponding light-absorbing layer within the relatively closed second light-absorbing cavity, thereby minimizing the probability of the stray light passing through the beam-splitting structure returning to the entrance port. By spatially splitting and independently attenuating the stray light through the beam-splitting structure, the stray light is effectively confined within the light trap body and gradually attenuated, suppressing the stray light from entering the imaging optical path at the source, thereby improving the signal-to-noise ratio of fluorescence imaging.

[0026] To make the optical trapping device for suppressing stray light provided in the embodiments of this application clearer and easier to understand, the device will be described below in conjunction with the accompanying drawings. Figure 1 As shown, this figure is a structural diagram of a light trapping device for suppressing stray light provided in an embodiment of this application. The device includes: The light trap body 1 has a light-absorbing inner cavity, and an entrance port 2 is provided on one side of the light-absorbing inner cavity to receive stray light generated when the excitation light propagates; the inner wall of the light-absorbing inner cavity is provided with a light-absorbing layer to attenuate the energy of the stray light projected onto it. The beam-splitting structure is inclinedly arranged in the light-absorbing cavity to divide the light-absorbing cavity into a first light-absorbing cavity and a second light-absorbing cavity in sequence along the central optical axis of the stray light. The beam-splitting structure is provided with multiple light-transmitting holes 3, and the first light-absorbing cavity is connected to the second light-absorbing cavity through the light-transmitting holes 3. When stray light enters the first light-absorbing cavity through the entrance port 2, part of the stray light is incident on the beam-splitting structure and is attenuated by multiple reflections in the first light-absorbing cavity; the other part of the stray light enters the second light-absorbing cavity through the light-transmitting hole 3 and is attenuated by multiple reflections in the second light-absorbing cavity.

[0027] The light trap body 1 is a metal box structure, such as a hollow cuboid structure made of 5052 aluminum alloy. The hollow interior of the light trap body 1 forms a light-absorbing cavity, which provides space for the attenuation of stray light energy. The entrance port 2 is located on the front side of the light-absorbing cavity along the direction of stray light propagation. The entrance port 2 serves as a light-entry opening to receive stray light from the LED excitation light that has not participated in sample excitation and has leaked through the filter structure. Furthermore, the cross-sectional area of ​​the entrance port 2 is greater than or equal to the area of ​​the stray light spot on the plane where the entrance port is located, ensuring that all interfering stray light is incident into the light-absorbing cavity without any leakage.

[0028] The beam-splitting structure, as the core structure of this device for achieving spatial splitting and graded attenuation of stray light, is obliquely arranged inside the light-absorbing cavity, dividing the cavity into a first and a second light-absorbing cavity. A portion of the stray light in the first cavity is dissipated, while the remaining stray light passes through the light-transmitting hole 3 and enters the second cavity for attenuation. Structurally, this prevents stray light from reflecting back along its original path and improves the overall light absorption suppression effect. Specifically, as... Figure 1 As shown, the beam-splitting structure includes: The beam-splitting baffle 4 is inclined and forms a first angle with the central optical axis of the stray light incident through the entrance port. The opening of the first angle faces the second light-absorbing cavity. Both outer surfaces of the beam-splitting baffle 4 are provided with light-absorbing layers.

[0029] Here, the beam-splitting baffle 4 is installed obliquely inside the light-absorbing cavity of the light trap body 1. The beam-splitting baffle 4 and the central optical axis of the stray light entering the light-absorbing cavity from the entrance port 2 are arranged obliquely to each other and form a first angle. The opening of this first angle is biased towards the second light-absorbing cavity. This tilted layout alters the propagation path of stray light, preventing specular reflection after the stray light strikes the beam-splitting baffle 4. Instead, it deflects and scatters the reflected light towards the inner walls of the first absorption cavity, effectively extending the optical path of the stray light within the cavity and increasing the number of reflection contacts between the stray light and the corresponding absorption layer. This allows for gradual dissipation of light energy through multiple diffuse reflections. Simultaneously, both the front and back outer surfaces of the beam-splitting baffle 4 are fully covered with absorption layers, enabling simultaneous absorption and diffuse attenuation of stray light incident on the front of the beam-splitting baffle 4 and stray light returning from the second absorption cavity.

[0030] Furthermore, the first included angle range is, for example, 40°~50°. This angle range can adapt to the stray light incident characteristics of the large divergence angle of the LED light source. It can ensure that the stray light that does not pass through the light-transmitting hole is fully diffusely attenuated in the first light-absorbing cavity, and also allow some stray light to pass smoothly through the light-transmitting hole into the second light-absorbing cavity. In the closed second light-absorbing cavity, multiple diffuse reflections are completed to completely extinct the light, realizing the spatial splitting and graded attenuation of stray light, and suppressing the backflow of stray light to the imaging optical path from the structural source.

[0031] If the first angle is less than 40°, the beam splitter 4 is placed too gently, and the surface of the beam splitter 4 is close to the direction of stray light incident. The incident stray light is prone to straight transmission or near-angle reflection, and it is difficult to effectively deflect to the inner wall of the first light absorption cavity. The number of reflections of light in the first light absorption cavity is greatly reduced, the energy attenuation of stray light is insufficient, and residual light is very likely to escape and flow back. If the first angle is greater than 50°, the beam splitter 4 is placed too steeply, and the surface is even closer to the direction of stray light incident. The stray light is easily reflected back directly towards the entrance by the mirror, and it is very easy to escape back along the original light path and enter the imaging light path, thus losing the stray light suppression effect of the light trap. The 40° to 50° angle range, preferably 45°, allows the incident stray light to be uniformly deflected to the sidewalls of the first absorption cavity after being reflected by the beam splitter 4. This maximizes the extension of the light propagation path and increases the number of diffuse reflections, while not obstructing the normal transmission and splitting of stray light through the light-passing hole to the second absorption cavity. This adapts to the large divergence angle of the stray light excited by the LED, takes into account the graded attenuation effect of the front and rear cavities, and ensures that the stray light is fully confined and dissipated inside the light trap body, significantly improving the signal-to-noise ratio and imaging contrast of the fluorescence imaging system.

[0032] Furthermore, the beam-splitting baffle 4 is welded to the inner wall of the light-absorbing cavity, achieving a seamless and sealed connection. This seals off assembly gaps, preventing stray light leakage and crosstalk from the gap between the beam-splitting baffle 4 and the light-absorbing cavity, and preventing stray light from bypassing the beam-splitting structure and escaping directly back to the incident light path. In addition, the welded integrated structure has high overall rigidity and is unaffected by external factors such as equipment vibration and changes in ambient temperature and humidity. It can maintain the spatial division of the dual light-absorbing cavities and the stray light splitting and attenuation effect over a long period, improving the overall structural stability and operational reliability of the device.

[0033] Furthermore, the light-absorbing layer includes: The micro-particle rough structure is set on the inner wall of the light-absorbing cavity and the surface of the beam-splitting baffle 4. A black light-absorbing coating layer is disposed on the side of the micro-particle rough structure away from the inner wall of the light-absorbing cavity or the surface of the beam-splitting baffle 4.

[0034] The micro-particle rough structure is disposed on the inner wall of the light-absorbing cavity and on the entire surface of the beam-splitting baffle 4. Its microscopic, uneven particle morphology alters the reflection mode of stray light, converting traditional specular reflection into irregular diffuse reflection, preventing directional light backscattering, and simultaneously increasing the contact area between the light and the corresponding surface layer, providing the basic structural conditions for light energy absorption. A black light-absorbing coating layer is stacked on the outer surface of the micro-particle rough structure, facing away from the inner wall of the light-absorbing cavity or the beam-splitting baffle 4. Utilizing the inherent high light absorption rate of the black material, it efficiently attenuates stray light incident on the surface.

[0035] Here, the black light-absorbing coating layer can be either a black anodized layer or a matte black light-absorbing coating layer. When using a black anodized layer, a dense and stable blackened oxide film can be formed on the metal substrate surface, exhibiting high adhesion strength, wear resistance, and resistance to aging and peeling, making it suitable for long-term closed-cavity working environments. When using a matte black light-absorbing coating layer, the coating application is convenient and uniform, effectively filling the microscopic gaps in the rough microparticle structure, further reducing surface reflectivity. Both layer structures maintain high absorbency within the commonly used excitation wavelength range for biomedical fluorescence imaging, significantly absorbing stray light energy during each diffuse reflection process. Combined with the diffuse reflection effect of the rough microparticle structure, stray light rapidly attenuates to an extremely low level during multiple cavity reflections, ensuring the stray light suppression performance of the light trapping device from the surface structure level.

[0036] Furthermore, such as Figure 2As shown, the light-transmitting holes 3 are arranged in a regular matrix, which enables the stray light passing through the beam-splitting baffle 4 to be spatially uniformly distributed, avoiding problems such as light leakage or insufficient local attenuation caused by local optical path concentration, and ensuring the uniformity and consistency of stray light splitting. For example, the light-transmitting holes 3 are circular, which simplifies the manufacturing process, ensures regular forming, and provides uniform stress distribution. This avoids disordered scattering of stray light caused by burrs on the hole edges and structural corners, and facilitates the controlled and guided stray light to smoothly penetrate the beam-splitting baffle 4 and enter the second light-absorbing cavity for multiple diffuse reflection attenuations. The total aperture ratio of the multiple circular light-transmitting holes is, for example, 40%~60%, which can achieve the optimal splitting ratio of stray light energy. If the total aperture ratio is less than 40%, the proportion of light energy entering the second absorption cavity through the light-transmitting hole 3 is too small, and most of the stray light is attenuated only in the first absorption cavity, which can easily lead to excessive light load and incomplete attenuation in the first absorption cavity. If the total aperture ratio is greater than 60%, the area blocked by the beam-splitter 4 is too small, and the diffuse reflection attenuation area is insufficient. A large amount of stray light is directly transmitted into the second absorption cavity, which can easily lead to reflection backflow from the second absorption cavity and backflow from the light-transmitting hole 3 into the first absorption cavity. An aperture ratio of 40% to 60% allows some stray light to dissipate energy through multiple diffuse reflections in the first absorption cavity by the beam-splitter 4 and the corresponding light-absorbing layer, while the other part of the stray light enters the second absorption cavity evenly for closed attenuation. This achieves balanced and graded light absorption in both cavities, maximizes the overall stray light capture and attenuation efficiency, effectively suppresses the backflow of excitation stray light into the imaging optical path, and ensures the signal-to-noise ratio and imaging quality of fluorescence imaging.

[0037] Furthermore, the outer surface of the light trap body 1 is provided with a mounting structure for connection with the fluorescence imaging system. The mounting structure can adopt any one or more combinations of mounting ears, fixed threaded holes, and snap-fit ​​slots. This mounting structure allows the entire light trap device to be quickly assembled into the designated mounting position inside the fluorescence imaging system, facilitating precise alignment between the light trap device's inlet 2 and the location where stray light is generated in the imaging optical path, ensuring that stray light can enter the light-absorbing cavity without deviation and with full coverage. At the same time, this mounting structure allows for detachable assembly, facilitating equipment assembly, subsequent inspection, maintenance, and replacement, and adapting to the installation requirements of LED-excited biomedical fluorescence imaging equipment of different models and structural layouts.

[0038] like Figure 3 As shown, this application also provides a biomedical fluorescence imaging system, comprising: LED excitation source 5, LED excitation source 5 is used to generate excitation light for exciting fluorescent sample 12; An imaging optical path is provided, with the incident end of the imaging optical path and the light-emitting end of the LED excitation source 5 correspondingly set. The imaging optical path is used to guide the excitation light to the fluorescent sample 12 and collect the fluorescence signal emitted by the fluorescent sample 12 after it is excited. The aforementioned optical trapping device for suppressing stray light has its inlet facing the location where stray light is generated in the imaging optical path. The optical trapping device is used to collect and attenuate stray light that is not excited by the fluorescent sample 12, and to suppress stray light from entering the imaging optical path. Fluorescence imaging structure 6 is located at the output end of the imaging optical path and is used to receive fluorescence signals and image them.

[0039] It should be noted that the system has a main unit housing 11, which serves as the external encapsulation and protective shell for the entire biomedical fluorescence imaging system. It encapsulates all optical and mechanical components, including the LED excitation light source 5, imaging optical path, light trapping device, fluorescence imaging structure 6, fixing stage 9, and mounting stage 10, in a completely sealed manner. On the one hand, it can isolate stray light, dust, and temperature and humidity interference from the external environment, preventing ambient light from entering the imaging optical path and causing imaging noise. On the other hand, it can shield the internal optical path from scattering light from leaking outwards, while providing physical protection, shock absorption, and safety protection for the internal optical components and mechanical structures. This makes the entire imaging system compact, highly integrated, and suitable for the miniaturization and portability requirements of the instrument.

[0040] The LED excitation source 5 serves as the excitation light generation unit of the entire fluorescence imaging system, capable of outputting monochromatic excitation light of a specific wavelength to provide the light energy required for stimulated emission of the fluorescent markers inside the fluorescent sample 12. Compared with traditional mercury lamps, xenon lamps, and laser light sources, the LED excitation source 5 features small size, low power consumption, low heat generation, rich wavelength selection, long lifespan, and low cost, making it suitable for the design requirements of miniaturized and portable biomedical fluorescence imaging equipment. At the same time, the LED light source has a large emission divergence angle, which can meet the excitation and illumination requirements of large-area samples. However, its large divergence angle also easily generates a large amount of transmitted and scattered stray light, which needs to be effectively suppressed in conjunction with a subsequent light trap device.

[0041] The incident end of the imaging optical path is precisely aligned with the emitting end of the LED excitation source 5 to ensure that the excitation light can be efficiently coupled into the interior of the optical path. On the one hand, the imaging optical path collimates, deflects, and focuses the LED excitation light, accurately projecting the excitation light onto the surface of the fluorescent sample 12 to achieve stable excitation of the sample's fluorescent groups. On the other hand, the imaging optical path reverses and collects the weak fluorescence signal emitted by the fluorescent sample 12 after excitation, and filters, collimates, and directionally transmits the fluorescence signal, transferring the effective fluorescence signal to the downstream fluorescence imaging structure 6 without loss.

[0042] Furthermore, the imaging optical path includes: The microscope objective 7 is positioned between the stage 9, which is used to support the fluorescent sample 12, and the fluorescence imaging structure 6. The microscope objective 7 is used to focus the excitation light onto the fluorescent sample 12 and collect the fluorescence signal emitted by the fluorescent sample 12 after it is excited. The filter structure 8 is disposed between the microscope objective 7 and the fluorescence imaging structure 6. It is used to reflect the excitation light from the LED excitation source 5 to the microscope objective 7 and transmit the fluorescence signal collected by the microscope objective 7 to the fluorescence imaging structure 6. The entrance port 2 of the light trap device is correspondingly disposed with the filter structure 8 to collect stray light that is transmitted through the filter structure 8 but not reflected to the fluorescence sample 12.

[0043] Among them, the microscope objective 7 can, on the one hand, perform beam convergence and focusing processing on the LED excitation light reflected from the filter structure 8, so that the excitation light is precisely focused and projected onto the surface of the fluorescent sample 12 placed on the fixed stage 9, ensuring that the excitation light energy is concentrated and the excitation area is controllable, and realizing efficient excitation of the fluorescent groups of the sample; on the other hand, it can reverse the acquisition of the weak fluorescence signal emitted by the stimulated emission of the fluorescent sample 12, perform optical amplification and collimation shaping on the fluorescence signal, and transmit the regulated fluorescence signal upward to the filter structure 8, providing a high-fidelity, high-resolution original fluorescence light signal for the back-end fluorescence imaging structure 6.

[0044] The fixed stage 9 serves as the support stage for the fluorescent sample 12. It is located at the optical path focusing position of the imaging optical path and is used to stably place and limit the fluorescent sample 12, ensuring that the sample imaging position is centered and the optical path is accurately focused. Here, the fixed stage 9 can adopt a translation or fine adjustment structure, which can realize the micro-alignment adjustment of the sample position, making it convenient to complete the fluorescence imaging acquisition of different test areas. At the same time, it has the functions of structural stability, light protection and vibration reduction, avoiding the impact of external vibration and positional displacement on the imaging clarity.

[0045] The filter structure 8 utilizes its spectral selectivity to achieve optical path separation between the excitation light and the fluorescence signal: it generates high reflection of the specific wavelength excitation light emitted by the LED excitation source 5, redirecting and reflecting the excitation light towards the microscope objective 7, and then projecting it onto the fluorescent sample 12 to complete the excitation; simultaneously, it possesses high transmission characteristics for the long-wavelength fluorescence signal generated by the fluorescent sample 12, allowing the fluorescence signal to pass smoothly through the filter structure 8 and be transmitted to the downstream fluorescence imaging structure 6 for imaging acquisition. Due to limitations in fabrication process and optical cutoff performance, the filter structure 8 cannot achieve 100% total internal reflection of the excitation light; some excitation light will always directly pass through the filter structure 8, forming ineffective stray light. The entrance port 2 of the light trap device is aligned with the stray light transmission side of the filter structure 8. It receives redundant excitation stray light that has passed through the filter structure 8 and has not been reflected to the fluorescent sample 12. It collects redundant stray light from the LED excitation light that has not been projected onto the fluorescent sample 12 and has not participated in fluorescence excitation. Using the dual-cavity structure formed by the internal tilted beam splitter 4, the stray light is confined inside the device through diffuse reflection and layered attenuation, gradually dissipating its energy. This blocks stray light backflow and crosstalk into the imaging optical path from the source, preventing high-intensity excitation stray light from overwhelming the weak fluorescence signal and providing a high-purity fluorescence optical path environment for subsequent imaging.

[0046] The mounting platform 10 is located inside the main unit housing 11 and is used to install the light trapping device. The light trapping device can be mounted on the mounting platform 10 through the mounting structure on its outer surface. This enables high-precision optical path alignment between the light trapping device inlet 3 and the filter structure 8, ensuring that stray light can enter the light trapping device without deviation and with full coverage. At the same time, it also serves as a shock absorber, support, and positioning limiter to prevent displacement and tilt deviation during device use.

[0047] The fluorescence imaging structure 6 is positioned at the output end of the imaging optical path, serving as a receiver and imaging execution component for fluorescence signals. It is responsible for receiving the valid fluorescence signals after they have been filtered and transmitted through the imaging optical path. It converts the optical signals into electrical signals and completes signal acquisition, image processing, and imaging output, ultimately forming an observable and analyzable fluorescence image of the biological sample. Thanks to the stray light suppression effect of the light trapping device, the fluorescence signal received by the fluorescence imaging structure 6 is free from strong excitation light interference, significantly improving the imaging signal-to-noise ratio, image contrast, and weak signal detection capability, meeting the high-precision fluorescence detection imaging requirements for biological tissue sections, live animals, and single cells.

[0048] This system can be widely used in biomedical testing scenarios such as tissue section fluorescence imaging, live small animal fluorescence imaging, single-cell detection, and in situ imaging of tumor markers.

[0049] To facilitate understanding, the biomedical fluorescence imaging system in this application will be described below with specific examples.

[0050] The light trap device is made of 5052 aluminum alloy. The light trap body 1 is a rectangular hollow metal box structure with an overall length of 90mm, width of 30mm, height of 30mm, and a wall thickness of 1mm. The light transmission size of the front entrance of the light trap device is set to 30mm×30mm, which is perfectly matched with the size of the stray light spot. It can completely cover the entire range of stray light after the LED excitation light passes through the filter structure, with no light leakage or escape.

[0051] The inclined beam-splitter 4 inside the light trap device is made of 0.5mm thick 5052 aluminum alloy sheet. The beam-splitter 4 is inclined at a 45° angle to the central optical axis of the stray light, which is within the preferred angle range of 40° to 50°. The beam-splitter 4 is welded and sealed to the inner wall of the box at a position 60mm away from the end face of the entrance port 3, without assembly gaps, to prevent stray light from escaping through gaps. The surface of the beam-splitter 4 has circular light-transmitting holes arranged in a square matrix. The diameter of a single hole is 3.42mm, the center-to-center distance between adjacent holes is 5mm, and they are arranged in a 7-column × 7-row array. The total aperture ratio is controlled at 50%, which is within the reasonable aperture ratio range of 40% to 60%. This allows about 50% of the stray light to pass through the light-transmitting holes into the second light-absorbing cavity, while the remaining 50% of the stray light is diffusely reflected and attenuated in the first light-absorbing cavity.

[0052] All inner walls of the light trap device and the front and back surfaces of the beam splitter 4 are first sandblasted to form a micro-particle rough structure with a roughness Ra of 6.3μm. Then, black anodizing is performed to form a matte black light-absorbing layer with a thickness of 12μm. In the commonly used excitation wavelength range of 405nm, 488nm, 561nm and 640nm in biomedicine, the light absorption rate can reach more than 96%, and most of the light energy can be absorbed by a single diffuse reflection.

[0053] In this example of a biomedical fluorescence imaging system, a 488nm LED is selected as the excitation source, and the emitting end of the LED excitation source is precisely aligned with the incident end of the imaging optical path. A standard microscope objective 7 and a filter structure 8 are configured in the imaging optical path. The filter structure 8 exhibits a small amount of transmission leakage to the 488nm excitation light; this high-intensity stray light is directed towards the entrance of the light trap device and is entirely guided into the inner cavity of the light trap. After entering, the stray light is attenuated in two paths. One path illuminates the solid area of ​​the beam-splitting baffle 4, undergoing 3-5 diffuse reflections between the inner wall of the first absorption cavity and the baffle, resulting in light energy attenuation to less than one ten-thousandth of the incident value. The other path enters the relatively enclosed second absorption cavity through the matrix light-passing aperture 3 and undergoes multiple diffuse reflections before being completely absorbed by the absorption layer.

[0054] In this specific example assembly, the system can almost completely suppress the excitation stray light generated by the large divergence angle of the LED light source, effectively compensating for the shortcomings of conventional filters, such as insufficient OD4-OD6 cutoff depth and light leakage. Simultaneously, compared to traditional conical or honeycomb-type single-cavity light traps, the dual-cavity hierarchical diffuse reflection structure of this device eliminates the problem of stray light specular reflection, significantly improving the signal-to-noise ratio and image contrast of fluorescence imaging. The entire device is compact, simple to manufacture, and requires no precision optical components. It can be directly integrated into fluorescence microscopes, tissue section scanners, live small animal fluorescence imagers, and portable fluorescence detection devices. It exhibits no bio-optical damage, good temperature and humidity stability, and can meet the high-sensitivity imaging application requirements of single-cell fluorescence detection, in-situ imaging of tumor markers, and acquisition of weak bio-fluorescence signals.

[0055] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A light trapping device for suppressing stray light, characterized in that, include: The light trap body (1) has a light-absorbing inner cavity, and an entrance port (2) is provided on one side of the light-absorbing inner cavity to receive stray light generated when the excitation light propagates; the inner wall of the light-absorbing inner cavity is provided with a light-absorbing layer to attenuate the energy of the stray light projected thereon. The beam-splitting structure is inclinedly disposed in the light-absorbing cavity, which is used to divide the light-absorbing cavity into a first light-absorbing cavity and a second light-absorbing cavity in sequence along the central optical axis of the stray light; the beam-splitting structure is provided with a plurality of light-transmitting holes (3), and the first light-absorbing cavity is connected to the second light-absorbing cavity through the light-transmitting holes (3); When the stray light enters the first light-absorbing cavity through the entrance port (2), a portion of the stray light is incident on the beam-splitting structure and is attenuated by multiple reflections in the first light-absorbing cavity; another portion of the stray light enters the second light-absorbing cavity through the light-transmitting hole (3) and is attenuated by multiple reflections in the second light-absorbing cavity.

2. The optical trapping device for suppressing stray light according to claim 1, characterized in that, The beam-splitting structure includes: A beam-splitting baffle (4) is inclined and forms a first angle with the central optical axis of stray light incident through the entrance port. The opening of the first angle faces the second light-absorbing cavity. The light-absorbing layer is provided on both outer surfaces of the beam-splitting baffle (4).

3. A light trapping device for suppressing stray light according to claim 2, characterized in that, The light-absorbing layer includes: The micro-particle rough structure is disposed on the inner wall of the light-absorbing cavity and on the surface of the beam-splitting baffle (4); A black light-absorbing coating layer is disposed on the side of the micro-particle rough structure away from the inner wall of the light-absorbing cavity or the surface of the beam-splitting baffle (4).

4. A light trapping device for suppressing stray light according to claim 3, characterized in that, The black light-absorbing coating is a black anodized layer or a matte black light-absorbing coating layer; the angle range of the first included angle is 40°~50°.

5. A light trapping device for suppressing stray light according to claim 1, characterized in that, The light-transmitting holes (3) are arranged in a regular matrix. The light-transmitting holes (3) are circular light-transmitting holes, and the total opening rate of the multiple circular light-transmitting holes is 40%~60%. The light trap body (1) is a metal box structure.

6. A light trapping device for suppressing stray light according to claim 1, characterized in that, The cross-sectional area of ​​the entrance (2) is greater than or equal to the area of ​​the stray light spot on the plane where the entrance is located.

7. A light trapping device for suppressing stray light according to claim 2, characterized in that, The beam-splitting baffle (4) is welded to the inner wall of the light-absorbing cavity.

8. A light trapping device for suppressing stray light according to claim 1, characterized in that, The outer surface of the light trap body (1) is provided with an installation structure for connecting to a fluorescence imaging system.

9. A biomedical fluorescence imaging system, characterized in that, include: LED excitation source (5), which is used to generate excitation light for exciting fluorescent sample (12); An imaging optical path is provided, with the incident end of the imaging optical path and the light-emitting end of the LED excitation light source (5) correspondingly arranged. The imaging optical path is used to guide the excitation light to the fluorescent sample (12) and collect the fluorescence signal emitted by the fluorescent sample (12) after it is excited. The light trapping device for suppressing stray light according to any one of claims 1 to 8, wherein the entrance of the light trapping device is arranged toward the location where stray light is generated in the imaging optical path, and the light trapping device is used to collect and attenuate stray light that is not excited by the fluorescent sample (12) and suppress the stray light from entering the imaging optical path; A fluorescence imaging structure (6) is disposed at the emitting end of the imaging optical path to receive the fluorescence signal and image it.

10. A biomedical fluorescence imaging system according to claim 9, characterized in that, The imaging optical path includes: The microscope objective (7) is disposed between the stage (9) for supporting the fluorescent sample (12) and the fluorescence imaging structure (6). The microscope objective (7) is used to focus the excitation light onto the fluorescent sample (12) and collect the fluorescence signal emitted by the fluorescent sample (12) after it is excited. A filter structure (8) is disposed between the microscope objective (7) and the fluorescence imaging structure (6) to reflect the excitation light from the LED excitation source (5) to the microscope objective (7) and to transmit the fluorescence signal collected by the microscope objective (7) to the fluorescence imaging structure (6); the entrance port (2) of the light trapping device is correspondingly disposed with the filter structure (8) to collect stray light that has been transmitted through the filter structure (8) but has not been reflected to the fluorescence sample (12).

Images