Up-conversion imaging system for infrared image vision

Abstract

The invention provides an up-conversion imaging system for infrared image vision, comprising an up-conversion film for infrared imaging adapted to be 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: Yb < 3 + >, NaGdF4: Yb < 3 + >, Yb < 3 + >, Yb < 3 + >, Yb < 3 + >, Yb < 3 + >, Yb < 3 + >, Yb < 3 + >, Yb < 3 + >, Yb < 3 the polymer matrix comprises a copolymer which is formed by copolymerizing 2-hydroxyethyl methacrylate and methacrylic acid, and the polymer matrix comprises a copolymer which is formed by copolymerizing 2-hydroxyethyl methacrylate and methacrylic acid; the mass concentration of the up-conversion nanoparticles is 0.1%-10%; the thin film is used for converting near-infrared light with the wavelength ranging from 880 nm to 1532 nm into visible light with the wavelength ranging from 380 nm to 700 nm. The invention also provides a preparation method of the up-conversion sheet for infrared light imaging and an infrared light imaging system.

Description

Technical Field

[0001] The invention relates to the field of infrared visual imaging, and in particular to an up-conversion imaging system for infrared image vision. Background Art

[0002] Imaging vision is one of the most important ways for organisms, including humans, to obtain information from the outside world. It plays an important role in their life activities, such as obtaining food, mating, distinguishing directions, avoiding natural enemies, etc. In order to expand the spectral range of human imaging vision, upconversion nanoparticles are used in related technologies, which can convert 980nm infrared light into 535nm visible light. However, the conversion of near-infrared light will make the image converted from this near-infrared light out of the focal range of the human eye. Therefore, this near-infrared vision can often only perceive the temporal frequency and light intensity of the near-infrared, making it difficult to perform fine imaging.

[0003] Therefore, there is a need for an infrared imaging method that can achieve higher precision and can be more widely used 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 above-mentioned technical problems, the present invention provides an up-conversion imaging system for infrared image vision.

[0005] According to an embodiment of one aspect of the present invention, there is provided an up-conversion sheet for infrared light imaging, comprising:

[0006] A lens; and a film suitable for being attached to the lens, wherein:

[0007] The film comprises upconversion nanoparticles and a polymer matrix, wherein the upconversion nanoparticles are selected from upconversion gold nanoparticles Au / NaGdF4:Yb 3+ ,Er 3+ or trichromatic orthogonal multi-shell lanthanide nanoparticles NaErF4@NaYF4, the polymer matrix comprising a copolymer formed by copolymerization of 2-hydroxyethyl methacrylate and methacrylic acid;

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

[0009] The film is 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 embodiment of the present invention, there is provided a method for preparing an up-conversion film for infrared light imaging, comprising:

[0011] adding upconversion nanoparticles and a monomer solution including 2-hydroxyethyl methacrylate and methacrylic acid to obtain a mixed solution;

[0012] The mixture is added into a mold and irradiated with ultraviolet light to obtain a film;

[0013] The film is attached to the lens to obtain an up-conversion film.

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

[0015] A lens group includes a first lens and a second lens sequentially arranged on a near-infrared light transmission path;

[0016] The up-conversion film for infrared light imaging is arranged on the near-infrared light transmission optical path behind the first lens, and is used to convert the near-infrared light with a wavelength of 880nm~1532nm into visible light of 380nm~700nm.

[0017] According to an embodiment of the present invention, an upconversion film for infrared light imaging can be obtained by applying a film including upconversion nanoparticles and a polymer matrix to a lens. 3+ ,Er 3+ Or three-color orthogonal multi-shell lanthanide nanoparticles NaErF4@NaYF4 can convert near-infrared light with a wavelength of 880nm~1532nm into visible light of 380nm~700nm or visible light containing multiple colors; 2-hydroxyethyl methacrylate in the polymer matrix has good biocompatibility and has a similar refractive index to the upconversion nanoparticles, so that the upconversion film has better light transmittance and improves the clarity of infrared imaging. The methacrylic acid with a certain adhesion can make the film adhere to the lens without falling off. The upconversion film can be used in ordinary frame glasses, infrared imaging tube mirrors, infrared telescopes and other infrared imaging device systems, and can be widely used in infrared light imaging information recognition and transmission, and can be used in biomedicine, military, infrared information transmission such as display, anti-counterfeiting, encoding and decoding and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0019] Figure 1 A schematic diagram of preparing an up-conversion film according to an embodiment of the present invention;

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

[0021] Figure 3This is a schematic diagram of a device for testing the multi-color spatial resolution ability of visible light and near-infrared light of a person to be tested after wearing a tube-scope infrared imaging system according to an embodiment of the present invention;

[0022] Figure 4 This is a graph showing the test results of the visible light and near-infrared light multi-color spatial resolution ability of a person to be tested after wearing a tube-scope infrared imaging system according to an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of a device for testing the visible light and near-infrared light multi-color spatial pattern resolution ability of a person to be tested based on a tube mirror color infrared imaging system according to an embodiment of the present invention;

[0024] Figure 6 This is a graph showing the results of testing the visible light and near-infrared light multi-color spatial pattern resolution ability of a person under test based on a tube-mirror color infrared imaging system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] Below, 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 present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0026] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0027] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0028] In the process of realizing the concept of the present invention, it was found that by integrating upconversion nanoparticles into wearable contact lenses, human near-infrared light vision can be realized, which has opened up the research of human unconventional vision. However, the conversion of near-infrared light on contact lenses will cause the image converted from this near-infrared light to be out of the focal range of the human eye, that is, greater than 5 cm. When the upconversion particles are placed in the contact lens, the conversion process occurs on the contact lens. The contact lens is placed on the cornea, and the human eye cannot see things at the cornea. Therefore, this near-infrared vision can often only perceive the temporal frequency and light intensity of the near-infrared, and it is difficult to perform fine imaging. 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), thereby changing the spatial information carried by the direction of light propagation. Therefore, from the perspective of optical principles, this type of contact lens cannot achieve fine image perception.

[0029] For imaging vision, the clear objects seen by the human eye come from the light that is focused by the eye lens after it is incident. However, for the near-infrared light converted by the up-conversion film, the visible light converted by the nanoparticles after being excited by the near-infrared light is divergent at all angles, which changes the incident angle and information of the original near-infrared light, resulting in the inability to focus the light passing through the nano up-conversion film, and thus the inability to form an image. Therefore, a lens system is needed to focus the light on the up-conversion film for pattern excitation to form a clear image.

[0030] Specifically, according to an embodiment of one aspect of the present invention, there is provided an up-conversion sheet for infrared light imaging, comprising:

[0031] A lens; and a film suitable for being attached to the lens, wherein:

[0032] The film comprises upconversion nanoparticles and a polymer matrix, wherein the upconversion nanoparticles are selected from upconversion gold nanoparticles Au / NaGdF4:Yb 3+ ,Er 3+ or trichromatic orthogonal multi-shell lanthanide nanoparticles NaErF4@NaYF4, the polymer matrix comprising a copolymer formed by copolymerization of 2-hydroxyethyl methacrylate and methacrylic acid;

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

[0034] The film is used to convert near-infrared light with wavelengths ranging from 880nm to 1532nm into visible light ranging from 380nm to 700nm.

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

[0036] According to an embodiment of the present invention, an upconversion film for infrared light imaging can be obtained by applying a film including upconversion nanoparticles and a polymer matrix to a lens. 3+ ,Er 3+ Or three-color orthogonal multi-shell lanthanide nanoparticles NaErF4@NaYF4 can convert near-infrared light with a wavelength of 880nm~1532nm into visible light of 380nm~700nm or visible light containing multiple colors; 2-hydroxyethyl methacrylate in the polymer matrix has good biocompatibility and has a similar refractive index to the upconversion nanoparticles, so that the upconversion film has better light transmittance and improves the clarity of infrared imaging. The methacrylic acid with a certain adhesion can make the film adhere to the lens without falling off. The upconversion film can be used in ordinary frame glasses, infrared imaging tube mirrors, infrared telescopes and other infrared imaging device systems, and can be widely used in infrared light imaging information recognition and transmission, and can be used in biomedicine, military, infrared information transmission such as display, anti-counterfeiting, encoding and decoding and other fields.

[0037] According to another embodiment of the present invention, there is provided a method for preparing an up-conversion film for infrared light imaging, comprising:

[0038] adding upconversion nanoparticles and a monomer solution including 2-hydroxyethyl methacrylate and methacrylic acid to obtain a mixed solution;

[0039] The mixed liquid is added into a mold, and a film is obtained by ultraviolet irradiation;

[0040] The film is attached to the lens to obtain an up-conversion film.

[0041] According to an embodiment of the present invention, a method for preparing an upconversion film for infrared imaging based on upconversion nanoparticles can quickly prepare a film for infrared imaging by curing through a mold, and the prepared film can be attached to a lens through methyl methacrylate in the film to increase adhesion, thereby obtaining an upconversion film that can be used for infrared imaging. The preparation method has simple steps, low cost, and is convenient and fast.

[0042] Figure 1 This is a schematic diagram of preparing an up-conversion film according to an embodiment of the present invention.

[0043] According to an embodiment of the present invention, upconversion gold nanoparticles Au / NaGdF4:Yb 3+ ,Er 3+ The preparation method, such as Figure 1 As shown, including:

[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+ Add ligand chain polyvinyl pyrrolidone and chloroauric acid solution to the aqueous solution, stir and react, add reducing agent and centrifuge to obtain upconversion gold nanoparticles Au / NaGdF4:Yb 3+ ,Er 3+ .

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

[0047] According to an embodiment of the present invention, a method for synthesizing lanthanide core-shell nanoparticles tricolor orthogonal multi-shell lanthanide nanoparticles NaErF4@NaYF4 comprises:

[0048] Erbium chloride, oleic acid and octadecene are mixed, heated and then an alkali agent is added to obtain an alkali mixed solution;

[0049] Add NH4F to the alkali mixture, heat and stir, and then cool to obtain NaErF4 nanoparticles;

[0050] NaErF4 nanoparticles were prepared by epitaxial growth method to obtain lanthanide core-shell nanoparticles with NaYF4 as the shell and three-color orthogonal multi-shell lanthanide nanoparticles NaErF4@NaYF4.

[0051] According to an embodiment of the present invention, a uniform and continuous NaYF4 shell can be formed on the surface of NaErF4 nanoparticles through an epitaxial growth method, which can improve the stability and optical properties of the nanoparticles; the NaYF4 shell has a lower optical phonon energy, which can effectively reduce non-radiative transitions, thereby improving the up-conversion luminescence efficiency of the NaErF4 core, and 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, prevent agglomeration, and is beneficial to subsequent applications; nanoparticles with a core-shell structure can be synthesized through a few simple steps, which simplifies the synthesis process and reduces the difficulty of operation.

[0052] According to an embodiment of the present invention, a monomer 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 are stirred in a dark environment to obtain a mixed solution.

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

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

[0056] A lens group includes a first lens and a second lens sequentially arranged on a near-infrared light transmission path;

[0057] The up-conversion film for infrared light imaging is arranged on the near-infrared light transmission optical path behind the first lens, and is used to convert the near-infrared light with a wavelength of 880nm~1532nm into visible light of 380nm~700nm.

[0058] According to an embodiment of the present invention, the near-infrared light imaging system further includes a tube lens bracket, which is suitable for mounting an upper conversion 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, the first lens focuses the near-infrared image into an inverted real image, and projects it onto the upper conversion plate to convert the near-infrared image into a visible light image. Then the second lens inverts the visible image back to an upright real image. The third lens magnifies the real image into a virtual image within a focal length, while increasing the distance between the image and the human eye. K9 optical glass has excellent wide-spectrum transmittance characteristics and high transmittance in the wavelength range of 350nm-2000nm. K9 glass has excellent optical properties and can provide high transmittance and low distortion imaging effects, which helps to minimize light loss and distortion during near-infrared light transmission and ensure the clarity and accuracy of imaging; the design of the tube lens bracket enables the lens group and the upper conversion plate to be stably installed and adjusted to meet different imaging requirements, while ensuring the precise alignment and stability of the system and improving the imaging quality. The addition of the third lens can further adjust and optimize the optical path, so that the imaging system can more effectively process light of different wavelengths and improve the accuracy and reliability of imaging. The first lens focuses the near-infrared image into an inverted real image, and projects it onto the upper conversion plate to convert the near-infrared image into a visible light image. The second lens then inverts the visible image back into an erect real image. The third lens magnifies the real image into a virtual image within a focal length while increasing the distance of the image from the human eye.

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

[0062] According to an embodiment of the present invention, the first lens is usually used as the main lens of the system, responsible for converging the incident near-infrared light to the focal point. Since its focal length is 20 mm, it can image distant objects to a closer position, which is suitable for long-distance imaging. The second lens and the third lens are usually used as auxiliary lenses of the system, which can further adjust the optical path and improve the clarity and contrast of the imaging. Since its focal length is 15 mm, the light converged by the first lens can be further converged, or the light beam can be shaped to meet different imaging requirements. By combining the first lens, the second lens and the third lens, the second lens and the third lens can be used to correct the aberration of the first lens, or the light beam can be shaped into a desired shape, so that precise control of the near-infrared light can be achieved, thereby improving the performance of the imaging system. The focal distance between the first lens and the second lens is 52.06 mm, and the focal distance between the second lens and the third lens is recorded as 43.26 mm. The distance between the conversion plate on the plane and the focus 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, combined with the focal length between the first lens and the second lens, based on the optical path and the distance between the first lens and the second lens of 35 mm, it can be known that the lens group can be placed in an infinite imaging state, and an object at infinity can be imaged to a position at a finite distance, thereby improving the imaging quality.

[0065] The scheme of the present invention will be further explained below with reference to specific examples. Unless otherwise stated in the following examples, conventional commercial reagents are used.

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

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

[0068] Synthesis of upconversion nanoparticles NaGdF4: Yb by high temperature thermal decomposition method 3+ ,Er 3+ , the upconversion nanoparticles NaGdF4: Yb 3+ ,Er 3+ Dispersed in deionized water, and added with 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°C for 15 min, 900 μL of 100 mM ascorbic acid reducing agent was added and the reaction was stirred for 30 min. Au can be loaded on the surface of UCNPs.

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

[0071] In order to enhance the dispersion of UCNPs in contact lenses and remove oleic acid molecules, a modification process was performed: First, 50 mg of up-converted 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 h, followed by multiple rounds of centrifugation and washing. The nanomorphology of UCNPs was observed using a field emission scanning electron microscope (SEM, Gemini 500, CarlZeiss Jena, Germany) at an accelerating voltage of 3 kV. The results are shown in Figure 2. Figure 2 shown.

[0072] Figure 2 This is a scanning electron microscope image of upconversion nano-gold particles according to an embodiment of the present invention.

[0073] according to Figure 2 It can be seen that upconversion nano-gold particles with uniform size and no agglomeration are synthesized by the preparation method of the present invention.

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

[0075] 1mmol of erbium chloride (ErCl3·6H2O) was mixed with 6mL of oleic acid (OA) and 15mL of octadecene (ODE) in a 100mL three-necked round-bottom flask with a Schlenk line and a thermocouple temperature sensor. The mixture was then heated to 140°C and kept at this temperature for 60 minutes to remove the remaining water. After the mixture was cooled to room temperature, 2.5mmol of NaOH (100mg) dissolved in 5mL of CH3OH was added and stirred for 30 min, then the mixture was heated to 100°C, methanol was removed in vacuo, and cooled to room temperature to obtain a base mixture.

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

[0077] 0.2 mmol NaErF4 nanoparticles in cyclohexane were used as seeds, and 0.4 mmol Na-TFA and 0.4 mmol Y-TFA were added as precursor solutions for epitaxial growth of NaYF4 shells. 3.2 mL OA and 4.8 mL ODE were added, heated to 100 °C, and cyclohexane and other residues were removed in vacuo. 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 the reaction system was cooled to room temperature, the synthesized nanoparticles were centrifuged, washed three times with 1:1 volume ratio cyclohexane / ethanol, and finally dispersed in 2 ml cyclohexane for use. The lanthanide trifluoroacetate was synthesized by mixing lanthanide oxides with lanthanum trifluoroacetate, and the lanthanide core-shell nanoparticles NaErF4@NaYF4 were prepared by conventional epitaxial growth method.

[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. Stirring was carried out in a dark environment for 30 minutes, and finally the 2-hydroxyethyl methacrylate (pHEMA) monomer suspension was sealed to avoid visible light.

[0080] Add 1%-5% molar ratio of methacrylic acid (MAA) to hydroxyethyl methacrylate (HEMA) monomer, i.e., 9.7 mg ~ 48 mg MAA, to the pHEMA monomer suspension. After adding MAA to the solution, continue stirring for 10 minutes to ensure that MAA is evenly dispersed in the solution. During the stirring process, gradually add 3 mL of deionized water, keep stirring evenly, and pay attention to avoid stratification of the mixture. Then, weigh 0.085 g of 2-hydroxy-2-methylpropanone (HMP) and add it to the above solution, stir for 30 minutes in a dark environment, and finally seal the monomer suspension to avoid visible light to obtain a monomer solution including 2-hydroxyethyl methacrylate and methacrylic acid.

[0081] Example 4 Preparation of an upconversion film for infrared imaging

[0082] The upconversion nanoparticles prepared in Example 1 or Example 2 were added to the monomer solution including 2-hydroxyethyl methacrylate and methacrylic acid prepared in Example 3 and subjected to ultrasonic treatment. Then, it was immersed in a silicon wafer mold and irradiated with 365nm ultraviolet light for 20 minutes to catalyze the reaction. The film was further peeled off from the silicon wafer or mold and washed with a DI water / ethanol solution with a volume ratio of 1:1 at 50°C for 10 hours to remove unreacted monomers.

[0083] Upconversion gold nanoparticles Au / NaGdF4:Yb 3+ ,Er 3+ Thin films and thin films including tri-color orthorhombic multi-shell lanthanide nanoparticles NaErF4@NaYF4.

[0084] A clean lens is prepared, and two films for infrared imaging are evenly attached to the clean lens to obtain an up-conversion film 1 and an up-conversion film 2 respectively.

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

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

[0087] The upper conversion plate is arranged between the first lens and the second lens, and the distance from the focus of the first lens is recorded as v1, which is 20.69 mm, wherein the first lens, the upper conversion plate, the second lens and the third lens are arranged in a tube lens.

[0088] The two up-conversion plates prepared in Example 4 are installed in the tube mirror to obtain a tube mirror near-infrared light imaging system and a tube mirror color near-infrared light imaging system.

[0089] Example 6 Testing the visible light and near infrared light multi-color spatial resolution ability of the person under test based on the tube mirror infrared imaging system

[0090] Based on the tube mirror infrared imaging system constructed in Example 5, the test device is as follows Figure 3 As shown, a series of grating LED arrays composed of visible light and near-infrared light are prepared, and the subjects are asked to randomly distinguish the movement direction of the grating, i.e., vertical or horizontal, 10 times in each direction.

[0091] According to the accuracy of the subjects' answers to the direction of movement, a curve is drawn, and the spatial resolution of the subjects' visible light and near-infrared light is analyzed, such as Figure 4The highest resolvable spatial frequency of the subjects tested in the experiment was 65.46, which is close to the visible light spatial resolution that can be achieved by the naked human eye.

[0092] Figure 3 This is a schematic diagram of a device for testing the multi-color spatial resolution ability of visible light and near-infrared light of a person to be tested after wearing a tube-scope infrared imaging system according to an embodiment of the present invention; Figure 4 This is a graph showing the test results of the visible light and near-infrared light multi-color spatial resolution ability of a person under test after wearing a tube-scope 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 the near-infrared vision achieved by the test persons through the tube-scope near-infrared imaging system is significantly different from that of those who do not wear it, indicating that the tube-scope near-infrared imaging system can effectively distinguish infrared light patterns and has the same spatial resolution as that of visible light.

[0094] Example 7 Testing the ability of the subject to distinguish visible light and near-infrared light multi-color spatial patterns based on the tube-mirror color infrared imaging system

[0095] Using the same device as in Example 6 and the tube mirror color infrared imaging system built based on Example 5, the test device is as follows Figure 5 As shown, in order to verify the image recognition ability of the test person after wearing the lens imaging system, we used visible light and near-infrared light to make pairs of patterns of different colors: ━, ┃, ━; S, O, S; △, □, △.

[0096] The size of each paired shape is appropriate to ensure that the irradiation power intensity of each shape is the same. Among them, the color development area of ​​━ and ┃ is 0.576 cm 2 , the S and O color development area is 0.1355 cm 2 , the color-developing area of ​​△ and □ is 0.12cm 2 Each pattern has 5 colors. With the help of the color infrared imaging tube, the test subjects distinguish each pair of patterns of different colors within 60 cm. Each pair of patterns appears 50 times randomly, and each pattern of each color appears 5 times. The correct rate of the test subjects' answers to the pattern selection when wearing or not wearing the color infrared imaging tube is counted. The results are as follows: Figure 5 shown.

[0097] Figure 5 This is a schematic diagram of a device for testing the visible light and near-infrared light multi-color spatial pattern resolution ability of a person to be tested based on a tube mirror color infrared imaging system according to an embodiment of the present invention; Figure 6 This is a graph showing the results of testing the visible light and near-infrared light multi-color spatial pattern resolution ability of a person under test based on a tube-mirror color infrared imaging system according to an embodiment of the present invention.

[0098] according to Figure 6 It can be seen that the accuracy of the tested persons in distinguishing the visible light multi-color LED pattern and the near-infrared light multi-color pattern is basically the same when wearing or not wearing the tube-based color near-infrared imaging, indicating that the ability of the tube-based near-infrared color imaging system to distinguish infrared light color graphics is equivalent to that of visible light.

[0099] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only 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 in the protection scope of the present invention.

Claims

1. An upconversion film for infrared light imaging, comprising: lens; and a film suitable for being attached to the lens, wherein: The film comprises upconversion nanoparticles and a polymer matrix, wherein the upconversion nanoparticles are selected from upconversion gold nanoparticles Au / NaGdF4:Yb 3+ ,Er 3+ or tricolor orthogonal multi-shell lanthanide nanoparticles NaErF4@NaYF4, wherein the polymer matrix comprises a copolymer formed by copolymerization of 2-hydroxyethyl methacrylate and methacrylic acid; The mass concentration of the upconversion nanoparticles is 0.1% to 10%; 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.

2. A method for preparing the up-conversion film for infrared imaging as claimed in claim 1, comprising: adding upconversion nanoparticles and a monomer solution including 2-hydroxyethyl methacrylate and methacrylic acid to obtain a mixed solution; Adding the mixed solution into a mold, and subjecting the mold to ultraviolet irradiation to obtain the film; The film is attached to a lens to obtain the up-conversion film.

3. The preparation method according to claim 2, wherein The upconversion gold nanoparticles Au / NaGdF4:Yb 3+ ,Er 3+ The preparation method comprises: 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+ Add ligand chain polyvinyl pyrrolidone and chloroauric acid solution to the aqueous solution, stir and react, add reducing agent and centrifuge to obtain upconversion gold nanoparticles Au / NaGdF4:Yb 3+ ,Er 3+ .

4. The preparation method according to claim 2, wherein The synthesis method of the lanthanide core-shell nanoparticle tricolor orthogonal multi-shell lanthanide nanoparticle NaErF4@NaYF4 comprises: Erbium chloride, oleic acid and octadecene are mixed, heated and then an alkali agent is added to obtain an alkali mixed solution; Adding NH4F to the alkali mixture, heating and stirring, and then cooling to obtain NaErF4 nanoparticles; The NaErF4 nanoparticles are prepared by an epitaxial growth method to obtain lanthanide core-shell nanoparticles with NaYF4 as the shell, tricolor orthogonal multi-shell lanthanide nanoparticles NaErF4@NaYF4.

5. The preparation method according to claim 2, wherein: The monomer solution comprising 2-hydroxyethyl methacrylate and methacrylic acid is prepared by the following method: Ethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate, methacrylic acid and a photoinitiator are stirred in a dark environment to obtain the mixed solution.

6. A near-infrared imaging system, comprising: A lens group includes a first lens and a second lens sequentially arranged on a near-infrared light transmission path; The up-conversion film for infrared light imaging described in claim 1 is arranged in the near-infrared light transmission path located after the first lens, and is used to convert near-infrared light with a wavelength of 880nm~1532nm into visible light of 380nm~700nm.

7. The imaging system according to claim 6, wherein: A tube lens bracket, suitable for mounting the lens group and the upper conversion plate; and / or, The third lens is arranged on the near-infrared transmission light path behind the second lens.

8. The imaging system according to claim 7, wherein: The first lens, the second lens and the third lens are all K9 glass lenses.

9. The imaging system of claim 7, further comprising: The diameter of the first lens is 18 mm and the focal length is 20 mm; The diameters of the second lens and the third lens are both 12.7 mm, and the focal lengths are both 15 mm.

10. The imaging system according to claim 6 or 9, wherein: The distance between the first lens and the second lens is 35 mm.

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