Upconversion imaging system for infrared image vision

Abstract

The application provides an up-conversion imaging system for infrared image vision, comprising an up-conversion film for infrared light imaging, which is suitable for being attached to a lens, wherein the film comprises up-conversion nanoparticles and a polymer matrix, wherein the up-conversion nanoparticles are selected from up-conversion gold nanoparticles Au / NaGdF4:Yb3+, Er3+ or tricolor orthogonal multi-shell lanthanide nanoparticles NaErF4@NaYF4, the polymer matrix comprises a copolymer copolymerized from 2-hydroxyethyl methacrylate and methacrylic acid; the mass concentration of the up-conversion nanoparticles is 0.1% to 10%; and the film is used for converting near-infrared light with a wavelength of 880nm to 1532nm into visible light with a wavelength of 380nm to 700nm. The application also provides a preparation method of the up-conversion film for infrared light imaging and an infrared light imaging system.

Description

Technical Field

[0001] This invention relates to the field of infrared visual imaging, and more particularly to an upconversion imaging system for infrared image vision. Background Technology

[0002] Imaging vision is one of the most important ways for living organisms, including humans, to acquire information from the outside world, playing a crucial role in their life activities such as food acquisition, mating, orientation, and avoiding predators. To expand the spectral range of human imaging vision, upconversion nanoparticles have been used in related technologies to convert 980nm infrared light into 535nm visible light. However, the conversion of near-infrared light causes the resulting image to fall outside the focal range of the human eye. Therefore, this near-infrared vision often only perceives the time frequency and light intensity of the near-infrared spectrum, making it difficult to achieve fine imaging.

[0003] Therefore, a method for achieving higher precision infrared imaging is needed, which can then be more widely applied in the field of infrared imaging. Summary of the Invention

[0004] In view of this, in order to at least partially solve at least one of the aforementioned technical problems, the present invention provides an upconversion imaging system for infrared image vision.

[0005] According to one embodiment of the present invention, an upconversion chip for infrared imaging is provided, comprising:

[0006] Lenses; and films, suitable for attachment to lenses, wherein,

[0007] The thin film comprises upconversion nanoparticles and a polymer matrix, wherein the upconversion nanoparticles are selected from upconversion gold nanoparticles Au / NaGdF4:Yb 3+ Er 3+ Alternatively, tricolor orthogonal multishell lanthanide nanoparticles NaErF4@NaYF4, with a polymer matrix comprising a copolymer of 2-hydroxyethyl methacrylate and methacrylic acid;

[0008] The mass concentration of upconversion nanoparticles is 0.1%~10%;

[0009] Thin films are used to convert near-infrared light with wavelengths ranging from 880nm to 1532nm into visible light ranging from 380nm to 700nm.

[0010] According to another aspect of the present invention, a method for fabricating an upconversion plate for infrared imaging is provided, comprising:

[0011] A mixture was obtained by mixing upconversion nanoparticles with a monomer solution including 2-hydroxyethyl methacrylate and methacrylic acid;

[0012] The mixture is added to a mold and shaped into a thin film by ultraviolet irradiation;

[0013] The film is attached to the lens to obtain the upconversion lens.

[0014] According to another aspect of the present invention, a near-infrared imaging system is provided, comprising:

[0015] The lens group includes a first lens and a second lens arranged sequentially in the near-infrared light transmission optical path;

[0016] An upconversion plate for infrared imaging is positioned in the near-infrared light transmission path after the first lens to convert near-infrared light with wavelengths ranging from 880nm to 1532nm into visible light ranging from 380nm to 700nm.

[0017] According to an embodiment of the present invention, an upconversion sheet for infrared imaging can be obtained by attaching a thin film comprising upconversion nanoparticles and a polymer matrix onto a lens. The upconversion gold nanoparticles are Au / NaGdF4:Yb. 3+ Er 3+ The tricolor orthogonal multishell lanthanide nanoparticles NaErF4@NaYF4 can convert near-infrared light with wavelengths ranging from 880nm to 1532nm into visible light ranging from 380nm to 700nm, or visible light containing multiple colors. The 2-hydroxyethyl methacrylate in the polymer matrix has good biocompatibility and a similar refractive index to the upconversion nanoparticles, thus giving the upconversion sheet better light transmittance and improving the clarity of infrared imaging. The methacrylate, with its certain adhesive properties, allows the film to adhere to the lens without falling off. The upconversion sheet can be used in infrared imaging device systems such as ordinary eyeglasses, infrared imaging tubes, and infrared telescopes. It can be widely used in the imaging information recognition and transmission of infrared light and can be applied in fields such as biomedicine, military, and infrared information transmission such as display, anti-counterfeiting, and encoding / decoding. Attached Figure Description

[0018] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0019] Figure 1 This is a schematic diagram illustrating the fabrication of the upconversion sheet according to an embodiment of the present invention;

[0020] Figure 2 This is a scanning electron microscope image of upconversion gold nanoparticles according to an embodiment of the present invention;

[0021] Figure 3This is a schematic diagram of a testing device for testing the visible and near-infrared multicolor spatial resolution capability of a person wearing a tube-lens infrared imaging system, according to an embodiment of the present invention.

[0022] Figure 4 This is a test result diagram of the visible and near-infrared multicolor spatial resolution capability of the test subject after wearing the tube-lens infrared imaging system, according to an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of a testing device for testing the visible and near-infrared multi-color spatial pattern resolution capability of a person under test based on a tube lens color infrared imaging system, according to an embodiment of the present invention.

[0024] Figure 6 This is a diagram showing the results of testing the visible and near-infrared multicolor spatial pattern resolution capability of a test subject based on a tube lens color infrared imaging system, as an embodiment of the present invention. Detailed Implementation

[0025] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0026] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0027] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0028] In realizing this invention, it was discovered that by incorporating upconversion nanoparticles into wearable contact lenses, near-infrared vision can be achieved, opening up research into unconventional human vision. However, converting near-infrared light onto the contact lens causes the resulting image to be outside the focal range of the human eye, exceeding 5 cm. When the upconversion particles are placed inside the contact lens, the conversion process occurs on the lens itself, which rests on the cornea. Since the human eye cannot clearly see anything on the cornea, this near-infrared vision often only perceives the time frequency and intensity of near-infrared light, making fine imaging difficult. Infrared light (NIR light) originally carries spatial information for imaging, but before entering the human eye, it is converted into scattered visible light by upconversion contact lenses (UCLs), thus altering the spatial information carried by the light propagation direction. Therefore, from an optical perspective, this type of contact lens cannot achieve fine image perception.

[0029] In imaging vision, the clear images of objects seen by the human eye are formed by the focusing of light rays after they have passed through the lens of the eye. However, the near-infrared light converted by the upconversion plate is dispersed in various directions after the nanoparticles are excited by the near-infrared light, altering the original incident angle and information of the near-infrared light. This causes the light rays passing through the nano-upconversion plate to become unfocused, thus preventing the formation of an image. Therefore, a lens system is needed to focus the light rays onto the upconversion plate to generate a pattern and achieve a clear image.

[0030] Specifically, according to one embodiment of the present invention, an upconversion sheet for infrared imaging is provided, comprising:

[0031] Lenses; and films, suitable for attachment to lenses, wherein,

[0032] The thin film comprises upconversion nanoparticles and a polymer matrix, wherein the upconversion nanoparticles are selected from upconversion gold nanoparticles Au / NaGdF4:Yb 3+ Er 3+ Alternatively, tricolor orthogonal multishell lanthanide nanoparticles NaErF4@NaYF4, with a polymer matrix comprising a copolymer of 2-hydroxyethyl methacrylate and methacrylic acid;

[0033] The mass concentration of upconversion nanoparticles is 0.1%~10%;

[0034] Thin films are used to convert near-infrared light with wavelengths ranging from 880nm to 1532nm into visible light ranging from 380nm to 700nm.

[0035] According to embodiments of the present invention, the mass concentration of upconversion gold nanoparticles can be 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. The lens material can be a transparent material with high light transmittance, such as resin, optical glass, calcium fluoride, or barium fluoride.

[0036] According to an embodiment of the present invention, an upconversion sheet for infrared imaging can be obtained by attaching a thin film comprising upconversion nanoparticles and a polymer matrix onto a lens. The upconversion gold nanoparticles are Au / NaGdF4:Yb. 3+ Er 3+ The tricolor orthogonal multishell lanthanide nanoparticles NaErF4@NaYF4 can convert near-infrared light with wavelengths ranging from 880nm to 1532nm into visible light ranging from 380nm to 700nm, or visible light containing multiple colors. The 2-hydroxyethyl methacrylate in the polymer matrix has good biocompatibility and a similar refractive index to the upconversion nanoparticles, thus giving the upconversion sheet better light transmittance and improving the clarity of infrared imaging. The methacrylate, with its certain adhesive properties, allows the film to adhere to the lens without falling off. The upconversion sheet can be used in infrared imaging device systems such as ordinary eyeglasses, infrared imaging tubes, and infrared telescopes. It can be widely used in the imaging information recognition and transmission of infrared light and can be applied in fields such as biomedicine, military, and infrared information transmission such as display, anti-counterfeiting, and encoding / decoding.

[0037] According to another aspect of the present invention, a method for fabricating an upconversion plate for infrared imaging is provided, comprising:

[0038] A mixture was obtained by mixing upconversion nanoparticles with a monomer solution including 2-hydroxyethyl methacrylate and methacrylic acid;

[0039] The mixture is added to a mold and shaped into a thin film by ultraviolet irradiation;

[0040] The film is attached to the lens to obtain the upconversion lens.

[0041] According to embodiments of the present invention, an upconversion sheet for infrared imaging based on upconversion nanoparticles can be rapidly prepared by curing with a mold to obtain a thin film for infrared imaging. The prepared film can be attached to a lens by using methacrylic acid in the film to increase adhesion, thereby obtaining an upconversion sheet that can be used for infrared imaging. The preparation method is simple, low-cost, convenient and fast.

[0042] Figure 1 This is a schematic diagram illustrating the fabrication of the upconversion sheet in an embodiment of the present invention.

[0043] According to an embodiment of the present invention, upconversion gold nanoparticles Au / NaGdF4:Yb 3+ Er 3+ Preparation methods, such as Figure 1 As shown, it includes:

[0044] Upconversion nanoparticles NaGdF4:Yb 3+ Er 3+ Dispersed in water to obtain NaGdF4: Yb 3+ Er 3+ Aqueous solution;

[0045] In NaGdF4: Yb 3+ Er 3+ After adding ligand chain polyvinylpyrrolidone and chloroauric acid solution to an aqueous solution and stirring the reaction, a reducing agent was added and centrifuged to obtain upconversion gold nanoparticles Au / NaGdF4:Yb. 3+ Er 3+ .

[0046] According to embodiments of the present invention, the upconversion luminescence performance can be enhanced by combining gold nanoparticles with upconversion nanoparticles. By introducing gold nanoparticles onto the surface of upconversion nanoparticles, more functional groups can be introduced through surface modification of the gold nanoparticles, thus expanding the application range of upconversion nanoparticles. By introducing ligand chains polyvinylpyrrolidone (PVP) onto the surface of upconversion nanoparticles, their water solubility can be improved, and the biocompatibility of the nanoparticles can be enhanced, reducing potential toxicity to organisms.

[0047] According to embodiments of the present invention, a method for synthesizing lanthanide core-shell nanoparticles (NaErF4@NaYF4) with tricolor orthogonal multishells includes:

[0048] Erbium chloride, oleic acid, and octadecene are mixed and heated, and then an alkaline agent is added to obtain an alkaline mixture.

[0049] NaErF4 nanoparticles were obtained by adding NH4F to an alkaline mixture, heating and stirring, and then cooling.

[0050] NaErF4@NaYF4, a tricolor orthogonal multishell lanthanide nanoparticle with NaYF4 as the outer shell, was prepared by epitaxial growth of NaErF4 nanoparticles.

[0051] According to embodiments of the present invention, a uniform and continuous NaYF4 shell can be formed on the surface of NaErF4 nanoparticles via epitaxial growth, which can improve the stability and optical properties of the nanoparticles. The NaYF4 shell has a low optical phonon energy, which can effectively reduce non-radiative transitions, thereby improving the upconversion luminescence efficiency of the NaErF4 core. Moreover, the NaYF4 shell can protect the NaErF4 core from the influence of the external environment, improve the chemical stability of the nanoparticles, and extend their service life. The use of surfactants such as oleic acid and octadecene helps to improve the dispersibility of the nanoparticles and prevent agglomeration, which is beneficial to subsequent applications. Core-shell structured nanoparticles can be synthesized in a few simple steps, simplifying the synthesis process and reducing the difficulty of operation.

[0052] According to embodiments of the present invention, a monomeric solution comprising 2-hydroxyethyl methacrylate and methacrylic acid is prepared by the following method:

[0053] Ethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate, methacrylic acid, and a photoinitiator were stirred in the dark to obtain a mixture.

[0054] According to embodiments of the present invention, by stirring ethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate, methacrylic acid, and a photoinitiator in a dark environment, premature decomposition of the photoinitiator can be avoided, thereby improving photoinitiation efficiency during subsequent ultraviolet irradiation. Ethylene glycol dimethacrylate and N-vinylpyrrolidone (NVP) monomers are used to modify polycarbonate films, which can improve the optical properties of the prepared upconversion film, increase transmittance, and reduce light scattering.

[0055] According to another aspect of the present invention, a near-infrared imaging system is provided, comprising:

[0056] The lens group includes a first lens and a second lens arranged sequentially in the near-infrared light transmission optical path;

[0057] An upconversion plate for infrared imaging is positioned in the near-infrared light transmission path after the first lens to convert near-infrared light with wavelengths ranging from 880nm to 1532nm into visible light ranging from 380nm to 700nm.

[0058] According to an embodiment of the present invention, the near-infrared imaging system further includes a tube lens holder suitable for mounting an upconversion plate; and / or a third lens.

[0059] According to an embodiment of the present invention, the first lens, the second lens, and the third lens are all K9 glass lenses.

[0060] According to an embodiment of the present invention, a first lens focuses a near-infrared image into an inverted real image, which is then projected onto an upconversion plate to convert the near-infrared image to a visible light image. A second lens then inverts the visible image back into an upright real image. A third lens magnifies the real image into a virtual image within a focal length, while simultaneously increasing the distance between the image and the human eye. K9 optical glass possesses excellent broad-spectrum transmittance characteristics, exhibiting high transmittance in the 350nm-2000nm wavelength range. K9 glass also boasts superior optical performance, providing high transmittance and low distortion imaging effects, which helps to minimize light loss and distortion during near-infrared light transmission, ensuring image clarity and accuracy. The design of the tube lens holder allows the lens group and upconversion plate to be stably installed and adjusted to adapt to different imaging needs, while ensuring precise alignment and stability of the system, thus improving image quality. The addition of the third lens further adjusts and optimizes the optical path, enabling the imaging system to more effectively process light of different wavelengths, improving imaging accuracy and reliability. The first lens focuses a near-infrared image into an inverted real image, which is then projected onto an upconversion plate to convert the near-infrared image to a visible light image. The second lens then inverts the visible image back into an upright real image. The third lens magnifies the real image into a virtual image within a focal length, while simultaneously increasing the distance between the image and the human eye.

[0061] According to an embodiment of the present invention, the diameter of the first lens is 18mm and the focal length is 20mm; the diameter of the second lens and the third lens are both 12.7mm and the focal length is 15mm.

[0062] According to embodiments of the present invention, the first lens typically serves as the main lens of the system, responsible for focusing the incident near-infrared light onto a focal point. With a focal length of 20mm, it can image distant objects as if they were closer, making it suitable for long-distance imaging. The second and third lenses typically serve as auxiliary lenses, further adjusting the optical path and improving image sharpness and contrast. With a focal length of 15mm, they can further focus the light focused by the first lens or reshape the beam to adapt to different imaging needs. By combining the first, second, and third lenses, the second and third lenses can be used to correct aberrations in the first lens or reshape the beam into the desired shape, enabling precise control of near-infrared light and thus improving the performance of the imaging system. The focal distance between the first and second lenses is 52.06 mm, and the focal distance between the second and third lenses is 43.26 mm. The distance between the planar conversion plate and the focal point of the first lens is 20.69 mm, which can also be adjusted according to the object distance.

[0063] According to an embodiment of the present invention, the distance between the first lens and the second lens is 35 mm.

[0064] According to an embodiment of the present invention, considering the focal length between the first lens and the second lens, and based on the optical path and the distance between the first lens and the second lens being 35mm, it can be seen that the lens group can be in an infinity imaging state, which can image an object at infinity to a position at a finite distance, thereby improving the imaging quality.

[0065] The present invention will be further explained in conjunction with specific embodiments below. Unless otherwise stated, all reagents used in the following embodiments are commercially available reagents.

[0066] In the following embodiments, the term "resolution coefficient" refers to the accuracy of resolution, which is calculated by subtracting the probability of randomly judging the correct event from the proportion of all correct events. The expected accuracy of random judgment is (100 / n)%, where "n" represents the number of choices. The resolution coefficient formula is (subject response accuracy - (100 / n) %) / (100% - (100 / n) %).

[0067] Example 1 Upconversion gold nanoparticles Au / NaGdF4:Yb 3+ Er 3+ Synthesis

[0068] Upconversion nanoparticles NaGdF4:Yb were synthesized via high-temperature pyrolysis. 3+ Er 3+ The upconversion nanoparticles NaGdF4:Yb 3+ Er 3+ Disperse in deionized water and add 2 mL of 2.4 mM ligand chain polyvinylpyrrolidone (PVP) and 20 μL of 10 mM chloroauric acid solution, respectively.

[0069] After stirring at 25℃ for 15 min, 900 μL of 100 mM ascorbic acid reducing agent was applied, and the reaction was continued with stirring for 30 min. Au can be loaded onto the surface of UCNPs.

[0070] The modified nanoparticles were then centrifuged and washed repeatedly with deionized water (DI) to obtain purified upconversion gold nanoparticles Au / NaGdF4:Yb. 3+ Er 3+ .

[0071] To enhance the dispersion of UCNPs in contact lenses and remove oleic acid molecules, a modification process was performed: First, 50 mg of upconverted UCNPs were dispersed in 10 ml of deionized water. Then, 50 μL of 1 M HCl solution was added. The suspension was then magnetically stirred for 3 hours, followed by multiple rounds of centrifugation and washing. The nanomorphology of the UCNPs was observed using a field emission scanning electron microscope (SEM, Gemini 500, Carl Zeiss Jena, Germany) at an accelerating voltage of 3 kV. The results are as follows. Figure 2 As shown.

[0072] Figure 2 This is a scanning electron microscope image of upconversion gold nanoparticles in an embodiment of the present invention.

[0073] according to Figure 2 It can be seen that the preparation method of the present invention synthesizes upconversion gold nanoparticles that are uniform in size and do not agglomerate.

[0074] Example 2 Synthesis of tricolor orthogonal multishell lanthanide nanoparticles (tUCNPs)

[0075] 1 mmol of erbium chloride (ErCl3·6H2O) was mixed with 6 mL of oleic acid (OA) and 15 mL of octadecene (ODE) in a 100 mL three-necked round-bottom flask equipped with a Schlenk wire and a thermocouple temperature sensor. The mixture was then heated to 140 °C and held at this temperature for 60 minutes to remove residual water. After cooling the mixture to room temperature, 2.5 mmol of NaOH (100 mg) dissolved in 5 mL of CH3OH was added, and the mixture was stirred for 30 minutes. The mixture was then heated to 100 °C, and methanol was removed under vacuum. After cooling to room temperature, an alkaline mixture was obtained.

[0076] 4 mmol (148 mg) of NH4F dissolved in 10 mL of CH3OH was added to the alkaline mixture, and the mixture was stirred for 30 min. The mixture was then heated to 100 °C under vacuum to remove methanol and residual water. The transparent solution was heated to 300 °C and held for 60 min under a gentle argon flow at a heating rate of 10 °C / min. After cooling the reaction system to room temperature, the synthesized nanoparticles were centrifuged, washed three times with a 1:1 volume ratio of cyclohexane / ethanol, and finally dispersed in 10 mL of cyclohexane for later use, yielding NaErF4 nanoparticles.

[0077] Using 0.2 mmol NaErF4 nanoparticles in cyclohexane as seeds, a precursor solution containing 0.4 mmol Na-TFA and 0.4 mmol Y-TFA was added as NaYF4 shell epitaxial growth. 3.2 mL OA and 4.8 mL ODE were added, and the mixture was heated to 100 °C. Residues such as cyclohexane were removed under vacuum. Then, the mixture was heated to 300 °C for 60 min under a gentle argon flow at a heating rate of 10 °C / min. After cooling the reaction system to room temperature, the synthesized nanoparticles were centrifuged, washed three times with cyclohexane / ethanol at a volume ratio of 1:1, and finally dispersed in 2 mL of cyclohexane for later use. Lanthanide trifluoroacetate (NaErF4@NaYF4) was synthesized using a method involving a mixture of lanthanide oxides and lanthanum trifluoroacetate. Lanthanide core-shell nanoparticles were prepared using conventional epitaxial growth methods.

[0078] Example 3 Preparation of a monomer solution comprising 2-hydroxyethyl methacrylate and methacrylic acid

[0079] 0.085 g of ethylene glycol dimethacrylate was immersed in 4 mL of 2-hydroxyethyl methacrylate. Then, 3 mL of deionized water and 0.085 g of 2-hydroxy-2-methylpropenone were gradually added. The mixture was stirred in the dark for 30 minutes, and finally the 2-hydroxyethyl methacrylate (pHEMA) monomer suspension was sealed to prevent exposure to visible light.

[0080] Add 1%–5% (9.7 mg–48 mg) of hydroxyethyl methacrylate (HEMA) monomer methacrylic acid (MAA) to the pHEMA monomer suspension. After adding MAA, continue stirring for 10 minutes to ensure uniform dispersion. During stirring, gradually add 3 mL of deionized water, maintaining thorough mixing and avoiding separation. Then, weigh 0.085 g of 2-hydroxy-2-methylpropanone (HMP) and add it to the above solution. Stir in the dark for 30 minutes. Finally, seal the monomer suspension to prevent visible light, yielding a monomer solution containing 2-hydroxyethyl methacrylate and methacrylic acid.

[0081] Example 4: Fabrication of an upconversion plate for infrared imaging

[0082] The upconversion nanoparticles prepared in Example 1 or Example 2 were added to a monomer solution containing 2-hydroxyethyl methacrylate and methacrylic acid prepared in Example 3, and then subjected to ultrasonic treatment. The solution was then immersed in a silicon wafer mold and catalyzed by irradiation with 365 nm ultraviolet light for 20 min. The film was further peeled off from the silicon wafer or mold and washed with a 1:1 (v / v) DI water / ethanol solution at 50 °C for 10 h to remove unreacted monomers.

[0083] Upconversion gold nanoparticles Au / NaGdF4:Yb were prepared separately. 3+ Er 3+ Thin films and thin films including tricolor orthogonal multishell lanthanide nanoparticles NaErF4@NaYF4.

[0084] Prepare a clean lens, and then smoothly attach two thin films for infrared imaging onto the clean lens to obtain upconversion plate 1 and upconversion plate 2, respectively.

[0085] Example 5: Construction of a tube lens near-infrared imaging system

[0086] Prepare one first lens with φ=18mm and f1=20mm, and two lenses with φ=12.7mm and f1=15mm as the second and third lenses respectively. Fix the distance and position with an adjustable frame so that the distance p1 between the first and second lenses is 52.66mm and the distance p2 between the second and third lenses is 43.26mm.

[0087] The upconversion plate is positioned between the first lens and the second lens, and the distance between it and the focal point of the first lens is denoted as v1, which is 20.69 mm. The first lens, the upconversion plate, the second lens, and the third lens are all located within a single telescope.

[0088] The two upconversion plates prepared in Example 4 were installed inside the tube lens to obtain a tube lens near-infrared light imaging system and a tube lens color near-infrared light imaging system.

[0089] Example 6: Testing the visible and near-infrared multicolor spatial resolution capability of the test subject based on the tube-lens infrared imaging system.

[0090] Based on the tube-lens infrared imaging system built in Example 5, the testing device is as follows: Figure 3 As shown, a series of grating LED arrays composed of visible light and near-infrared light are prepared. The person being tested is asked to randomly distinguish the direction of motion of the grating, i.e., vertical or horizontal, 10 times in each direction.

[0091] Based on the accuracy of the subjects' responses regarding the direction of movement, curves were plotted to analyze the subjects' spatial resolution for visible and near-infrared light. Figure 4As shown. The highest resolvable spatial frequency of the subjects detected in the experiment was 65.46, which is close to the visible light spatial resolution achievable by the human naked eye.

[0092] Figure 3 This is a schematic diagram of a testing device for testing the visible and near-infrared multicolor spatial resolution capability of a person wearing a tube-lens infrared imaging system, according to an embodiment of the present invention. Figure 4 This is a test result diagram of the visible and near-infrared multicolor spatial resolution capability of the test subject after wearing the tube-lens infrared imaging system, according to an embodiment of the present invention.

[0093] according to Figure 4 It can be seen that the spatial resolution of near-infrared vision achieved by the subject through the tube lens near-infrared imaging system is significantly different from that without wearing it, indicating that the tube lens near-infrared imaging system can effectively distinguish infrared light patterns and has the same spatial resolution as that for distinguishing visible light.

[0094] Example 7: Testing the visible and near-infrared multicolor spatial pattern resolution capability of the test subject based on the tube lens color infrared imaging system.

[0095] Using the same apparatus as in Example 6 and the tube lens color infrared imaging system built based on Example 5, the test apparatus is as follows: Figure 5 As shown, in order to verify the ability of the test subject to recognize images after wearing the lens imaging system, we created pairs of patterns of different colors using visible light and near-infrared light: ━、┃、━; S、O、S; △、□、△.

[0096] The dimensions of each paired shape are appropriate to ensure that the irradiation power intensity of each shape is the same. The areas of the ━ and ┃ colorimetric regions are 0.576 cm². 2 The area of ​​the S and O colorimetric regions is 0.1355 cm². 2 The area of ​​the colored region for △ and □ is 0.12 cm². 2 Each pattern corresponds to five colors. Subjects, aided by tube-lens color infrared imaging, were tasked with distinguishing each pair of patterns of different colors within a 60-centimeter radius. Each pair of patterns appeared randomly 50 times, and each pattern of each color appeared 5 times. The accuracy rate of subjects' pattern selection responses was statistically analyzed, with and without tube-lens color infrared imaging. The results are as follows: Figure 5 As shown.

[0097] Figure 5 This is a schematic diagram of a testing device for testing the visible and near-infrared multi-color spatial pattern resolution capability of a person under test based on a tube lens color infrared imaging system, according to an embodiment of the present invention. Figure 6 This is a diagram showing the results of testing the visible and near-infrared multicolor spatial pattern resolution capability of a test subject based on a tube lens color infrared imaging system, as an embodiment of the present invention.

[0098] according to Figure 6 It can be seen that the accuracy of the test subjects in distinguishing visible light multicolor LED patterns and near-infrared multicolor patterns is basically the same whether or not they wear a tube lens for color near-infrared imaging. This indicates that the tube lens-based near-infrared color imaging system has the same ability to distinguish infrared color patterns as visible light.

[0099] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A near-infrared imaging system, comprising: The lens group consists of a first lens, a second lens, and a third lens arranged sequentially along the near-infrared light transmission path. An upconversion plate for infrared imaging is disposed in the near-infrared light transmission path after the first lens, for converting near-infrared light with wavelengths including 880nm~1532nm into visible light with wavelengths including 380nm~700nm; a tube lens holder is suitable for mounting the lens group and the upconversion plate. The diameter of the first lens is 18mm and the focal length is 20mm; The diameter of both the second and third lenses is 12.7 mm, and the focal length is 15 mm. The distance between the first lens and the second lens is 35mm; The upconversion plate for infrared imaging includes: Lens; and a film, suitable for attachment to said lens, wherein, The thin film comprises upconversion nanoparticles and a polymer matrix, wherein the upconversion nanoparticles are selected from upconversion gold nanoparticles Au / NaGdF4:Yb. 3+ Er 3+ Alternatively, tricolor orthogonal multishell lanthanide nanoparticles NaErF4@NaYF4, wherein the polymer matrix comprises a copolymer of 2-hydroxyethyl methacrylate and methacrylic acid; The mass concentration of the upconversion nanoparticles is 0.1% to 10%. The thin film is used to convert near-infrared light with wavelengths ranging from 880nm to 1532nm into visible light ranging from 380nm to 700nm.

2. The near-infrared imaging system according to claim 1, wherein, The method for preparing the upconversion plate for infrared imaging includes: A mixture was obtained by mixing upconversion nanoparticles with a monomer solution including 2-hydroxyethyl methacrylate and methacrylic acid; The mixture is added to a mold and shaped by ultraviolet irradiation to obtain the film; The film is attached to the lens to obtain the upconversion film.

3. The near-infrared imaging system according to claim 2, wherein, The upconversion gold nanoparticles Au / NaGdF4:Yb 3+ Er 3+ The preparation methods include: The upconversion nanoparticles NaGdF4:Yb 3+ Er 3+ Dispersed in water to obtain NaGdF4: Yb 3+ Er 3+ Aqueous solution; In the NaGdF4:Yb 3+ Er 3+ After adding ligand chain polyvinylpyrrolidone and chloroauric acid solution to an aqueous solution and stirring the reaction, a reducing agent was added and centrifuged to obtain upconversion gold nanoparticles Au / NaGdF4:Yb. 3+ Er 3+ .

4. The near-infrared light imaging system according to claim 2, wherein, The synthesis method of the tricolor orthogonal multishell lanthanide nanoparticles NaErF4@NaYF4 includes: Erbium chloride, oleic acid, and octadecene are mixed and heated, and then an alkaline agent is added to obtain an alkaline mixture. NH4F was added to the alkaline mixture, and the mixture was heated and stirred before cooling to obtain NaErF4 nanoparticles. The NaErF4 nanoparticles were prepared by epitaxial growth to obtain lanthanide core-shell nanoparticles with NaYF4 as the outer shell, namely NaErF4@NaYF4.

5. The near-infrared imaging system according to claim 2, wherein, The monomer solution comprising 2-hydroxyethyl methacrylate and methacrylic acid is prepared by the following method: The mixture was prepared by stirring ethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate, methacrylic acid and photoinitiator in the dark.

6. The near-infrared imaging system according to claim 1, wherein, The first lens, the second lens, and the third lens are all K9 glass lenses.

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