Fluorescence chemical sensor based on tilted light rays from light sheets processed by femtosecond laser micromachining
The light sheet tilted light ray fluorescence chemical sensor addresses the bulkiness and complexity of existing food safety detection by using femtosecond laser micromachining to create a portable, sensitive, and stable on-site detection system for food contaminants.
Patent Information
- Application Number
- CN202211325683.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-27
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2042-10-27
AI Technical Summary
Existing food safety detection equipment is cumbersome due to its bulkiness and requirement for specialized personnel, necessitating sample transfer, which complicates the testing process.
A light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining, comprising a laser source, collimator, compressor, multimode coreless optical fiber, and power detector, with a sensing area having varying cavity diameters and metal nanoparticle layers, enabling on-site detection with enhanced fluorescence intensity and stability.
The sensor achieves rapid, efficient, and portable food contaminant detection with high sensitivity and robustness, eliminating the need for sample transfer and specialized personnel, while maintaining detection accuracy.
Smart Images
Figure CN115753705B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of food safety detection, and in particular to a light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining. Background Art
[0002] In terms of food safety testing, the official standard testing methods are laboratory liquid chromatography, gas chromatography and mass spectrometry. The above three methods require the evaluation of the collected spectral data and the establishment of models to estimate the food safety quality. However, these methods require specialized personnel to take samples, because the testing equipment used is expensive and bulky, and the samples and the testing equipment are often not in the same place, and the samples need to be transferred to the testing equipment for testing. In other words, the existing testing equipment is relatively cumbersome for food safety testing.
[0003] Therefore, the existing technology still needs to be improved and developed. Summary of the invention
[0004] The technical problem to be solved by the present application is to provide a light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining in view of the deficiencies of the existing technology, so as to solve the problem that the detection process of the existing detection equipment for food safety detection is relatively cumbersome.
[0005] In order to solve the above technical problems, the present application provides a light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining, comprising:
[0006] case;
[0007] A laser source is disposed in the housing and is used to output laser light;
[0008] A collimator is arranged in the housing, the input end of the collimator is connected to the output end of the laser source, and the collimator is used to convert the output laser into parallel laser;
[0009] A compressor is disposed in the housing, an input end of the compressor is connected to an output end of the collimator, and the compressor is used to form a light sheet at a focus of the parallel laser light;
[0010] A multimode coreless optical fiber is arranged on the housing at one side of the compressor, wherein when the output laser of the laser source enters the multimode coreless optical fiber through the collimator and the compressor, the output laser enters the multimode coreless optical fiber at a preset tilt angle;
[0011] The multimode coreless optical fiber comprises a sensing area composed of multiple sections of cavities, and the diameters corresponding to the multiple sections of cavities are all different. The sensing area is provided with multiple nanocavities, each nanocavity is filled with a metal nanoparticle layer, and the outer layer of the metal nanoparticle layer is covered with a fluorescent material layer;
[0012] A power detector is arranged on the housing, connected to the multi-mode coreless optical fiber, and used for detecting fluorescence power.
[0013] In an implementation manner, the sensing area is a conical sensing area, wherein the conical sensing area includes a first column, a first conical column, a second column, a second conical column, and a third column connected in sequence.
[0014] In an implementation manner, the sensing area is a columnar sensing area, wherein the columnar sensing area includes a fourth column, a fifth column, and a sixth column connected in sequence, and a diameter of the fifth column is larger than that of the fourth column and the sixth column.
[0015] In one implementation, the sensing area is a microbubble sensing area, wherein the microbubble sensing area includes a seventh column, an annular body, and an eighth column connected in sequence, and the diameter of the annular body is larger than that of the seventh column and the eighth column.
[0016] In one implementation, the light sheet tilted light ray fluorescence chemical sensor further comprises:
[0017] A polarizer is arranged in the housing, the input end of the polarizer is connected to the output end of the collimator, the output end of the polarizer is connected to the input end of the compressor, and the polarizer is used to split the output laser into two.
[0018] In one implementation, the light sheet tilted light ray fluorescence chemical sensor further comprises:
[0019] A photoelectric detector is arranged in the housing, an input end of the photoelectric detector is connected to an output end of the collimator, and the photoelectric detector is used to correct the drift of the output power of the output laser.
[0020] In one implementation, the light sheet tilted light ray fluorescence chemical sensor further comprises:
[0021] A rotator is arranged in the shell, the input end of the rotator is connected to the output end of the collimator, the output end of the rotator is connected to the input end of the compressor, and the rotator is used to change the polarization state of the output laser.
[0022] In one implementation, the light sheet tilted light ray fluorescence chemical sensor further comprises:
[0023] The dimming mechanical platform is arranged on the housing and is used to control the incident angle of the light sheet transmitted into the multi-mode coreless optical fiber. The multi-mode coreless optical fiber is arranged on the dimming mechanical platform.
[0024] In one implementation, the light sheet tilted light ray fluorescence chemical sensor further comprises:
[0025] A long-pass filter is arranged in the housing and is located on a side of the multi-mode coreless optical fiber close to the sensing area. The output end of the long-pass filter is connected to the input end of the power detector. The long-pass filter is used to ensure that the energy received by the power detector comes from the fluorescence.
[0026] In one implementation, the light sheet tilted light ray fluorescence chemical sensor further comprises:
[0027] An integrating sphere is arranged in the housing, an output end of the integrating sphere is connected to an input end of the power detector, and the integrating sphere is used to enable the power detector to receive all the fluorescence.
[0028] Beneficial effects: The laser source, collimator, compressor, multi-mode coreless optical fiber and power detector of the present application have relatively small structural dimensions. After the above-mentioned laser source, collimator, compressor, multi-mode coreless optical fiber and power detector are installed on the shell, the specific size of the light sheet tilted light ray fluorescence chemical sensor is similar to some handheld instruments. Compared with the existing expensive and bulky detection equipment, the present embodiment has a simple structure and is easy to carry. It does not require special personnel to take samples and transfer samples, and can achieve detection with the same effect as the existing detection equipment, and can achieve rapid and efficient screening and detection of pollutants in on-site videos. In addition, the light sheet tilted light ray fluorescence chemical sensor of the present application is a new type of optical fiber chemical sensing system that generates a high-intensity evanescent field on the surface of a non-uniform multi-mode coreless optical fiber. The light sheet tilted light rays are excited and transmitted in the multi-mode coreless optical fiber to improve the sensitivity and robustness of the sensor. The localized surface plasma resonance formed by the metal nanoparticles further enhances the fluorescence intensity. The nanocavity structure of the optical fiber surface is processed by femtosecond laser micromachining technology to protect the metal nanoparticles from external influences, thereby improving the long-term stability and reusability of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without inventive work.
[0030] Figure 1Schematic diagram of the overall device of the light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining provided in this application.
[0031] Figure 2 A schematic diagram of the optical path of the light sheet tilted light ray entering the multi-mode coreless optical fiber in the light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining provided in the present application.
[0032] Figure 3 A schematic diagram of the structure of the sensing area in the light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining provided in the present application, wherein Figure a is a schematic diagram of the excitation of the light sheet tilted light ray in the sensing area; Figure b is a schematic diagram of the propagation of the light sheet tilted light ray in the sensing area as a spiral light ray; Figure c is a schematic diagram of the optical path of the propagation of the light sheet tilted light ray and the meridian light ray in the sensing area; Figure d is a schematic diagram of the structure of the metal nanoparticle layer, the fluorescent material layer and the nanocavity in the sensing area.
[0033] Figure 4 A schematic diagram of the structure of the sensing area in the light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining provided in the present application.
[0034] Figure 5 Another schematic diagram of the structure of the sensing area in the light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining provided in the present application.
[0035] Figure 6 This is another structural schematic diagram of the sensing area in the light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining provided in the present application.
[0036] Figure 7 This is a schematic diagram of the structure of the original area in the light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining provided in the present application.
[0037] In the figure: 1. laser source; 2. collimator; 3. compressor; 4. multimode coreless optical fiber; 41. sensing area; 42. metal nanoparticle layer; 43. fluorescent material layer; 44. nanocavity; 5. power detector; 6. polarizer; 7. photodetector; 8. rotator; 9. long-pass filter; 10. integrating sphere; 11. electric rotating stage; 12. three-axis electric translation stage. DETAILED DESCRIPTION
[0038] The present application provides a light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining. In order to make the purpose, technical solution and effect of the present application clearer and more specific, the present application is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.
[0039] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.
[0040] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as here.
[0041] The application content is further explained below through the description of embodiments in conjunction with the accompanying drawings.
[0042] In terms of food safety testing, the official standard testing methods are laboratory liquid chromatography, gas chromatography and mass spectrometry. The above three methods require the evaluation of the collected spectral data and the establishment of models to estimate the food safety quality. However, these methods require specialized personnel to take samples, because the testing equipment used is expensive and bulky, and the samples and the testing equipment are often not in the same place, and the samples need to be transferred to the testing equipment for testing. In other words, the testing process of existing testing equipment for food safety testing equipment is relatively cumbersome.
[0043] Fiber optic sensing has many advantages over other technologies, including immunity to electromagnetic interference, durability under high pressure and temperature, high sensitivity, and high specificity.
[0044] For this reason, Figure 1As shown, this embodiment provides a light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining, which can perform rapid and efficient screening and detection of on-site food contaminants. The light sheet tilted light ray fluorescence chemical sensor of this embodiment is used to detect liquid or water-soluble food, and the pollutant index detected is the pollutant concentration. The greater the pollutant concentration, the smaller the fluorescence power. In other words, the pollutant concentration can be determined by detecting the fluorescence power, thereby determining the food safety quality; the detection of fluorescence power is actually the detection of the excited fluorescence intensity, and the enhancement of fluorescence intensity is conducive to the detection of fluorescence power; in order to enhance The fluorescence intensity is convenient for detecting the fluorescence power and for screening and detecting food contaminants on site. The light sheet tilted light ray fluorescence chemical sensor comprises a housing (not shown in the figure), a laser source 1, a collimator 2, a compressor 3, a multimode coreless optical fiber 4 and a power detector 5. The laser source 1, the collimator 2 and the compressor 3 are all arranged in the housing, the multimode coreless optical fiber 4 and the power detector 5 are arranged on the housing, the output end of the laser source 1 is connected to the input end of the collimator 2, and the output end of the collimator 2 is connected to the input end of the compressor 3; when the output end of the laser source 1 When the laser passes through the collimator 2 and the compressor 3 and enters the multimode coreless optical fiber 4, the output laser forms a light sheet through the compressor 3, and controls the incident angle of the light sheet on the optical fiber end face of the multimode coreless optical fiber 4, and enters the multimode coreless optical fiber 4 at a preset tilt angle, so that the light sheet tilts the light rays in the multimode coreless optical fiber 4; the multimode coreless optical fiber 4 includes an induction area 41 composed of a plurality of cavities, and the diameters corresponding to the plurality of cavities are different. For example, if the plurality of cavities are three-segment cavities, the diameter of the cavity in the middle is different from the diameters of the cavities at the front and rear ends; in this embodiment, For example, by setting a sensing area 41 composed of multiple cavities in the multi-mode coreless optical fiber 4, and the diameters corresponding to the multiple cavities are all different, the light sheet tilted light rays entering the sensing area 41 can be caused to penetrate the core-cladding boundary due to the sudden change of the waveguide geometry in the multiple cavities (for example, the waveguide diameter becomes smaller), and interact with the outside in the form of an evanescent field. The smaller the waveguide diameter, the more evanescent fields are generated, similar to the resistance of a water pipe. A stronger evanescent field means more pump light (when a laser is used to excite fluorescence, it is called pump light) to pump the fluorophore to excite fluorescence, thereby enhancing the fluorescence intensity; see Figure 3In figure a, a plurality of metal nanoparticle layers 42 are arranged on the sensing area 41, and the outer layer of the metal nanoparticle layer 42 is covered with a fluorescent material layer 43. For example, a fluorescent material layer 43 such as a monoclonal antibody (FB1 molecule labeled with fluorescein isothiocyanate, FB1-FITC molecule) is used to coat the metal nanoparticle layer 42. The metal nanoparticles of the metal nanoparticle layer 42 are kept at a certain distance from the fluorescent molecules of the fluorescent material layer 43, which can further enhance the fluorescence intensity. Since the light sheet tilted light ray fluorescent chemical sensor must be flushed each time the liquid to be tested is detected to prevent affecting the next detection result; in order to prevent the metal nanoparticles of the metal nanoparticle layer 42 from being flushed away, the present embodiment uses a femtosecond laser micromachining system to accurately modify the plurality of metal nanoparticle layers 42. The surface of the coreless optical fiber 4 is formed to establish a nanocavity 44 array. It can be understood that the sensing area 41 is provided with a plurality of nanocavities 44 by femtosecond laser micromachining, and each nanocavity 44 is filled with a metal nanoparticle layer 42, which is used to physically protect the metal nanoparticle layer 42 after the metal nanoparticle layer 42 is attached to the nanocavity 44, and provides a perfect solution to the problem that the metal nanoparticle layer 42 is easily washed away, protects the metal nanoparticle layer 42 from external influences, and improves the long-term stability and repeatable practicality of the light sheet tilted light ray fluorescence chemical sensor, and the nanocavity 44 is filled with The nanoparticle layer will produce localized surface plasmon resonance, which can further enhance the fluorescence intensity. The type and shape of the metal nanoparticle layer 42 used can be changed. For example, the type can be a gold nanoparticle layer or a silver nanoparticle layer, and the shape can be a spherical particle layer or a rod-shaped particle layer. When the light sheet tilted light ray fluorescence chemical sensor of this embodiment is needed to detect the liquid to be tested, the sensing area 41 of the multimode coreless optical fiber 4 is first placed in the liquid to be tested, and a stable output laser is output through the laser source 1 of this embodiment. After the output laser passes through the collimator 2, the output laser is converted into a flat The parallel laser then passes through the compressor 3 to form a light sheet at the focus, and the incident angle of the light sheet on the optical fiber end face of the multi-mode coreless optical fiber 4 is controlled to form a preset inclined light sheet. The inclined light rays propagate in the multi-mode coreless optical fiber 4, and the fluorescence is absorbed by the fluorescent material in the sensing area 41 of the multi-mode coreless optical fiber 4, and then the fluorescence power of the liquid to be tested is specifically detected by the power detector 5, and the pollutant concentration is determined by the fluorescence power, and then the food safety quality of the liquid to be tested is determined; wherein, the laser source 1 is a polarized laser source 1, the collimator 2 is a plano-convex lens collimator 2, and the compressor 3 is a cylindrical plano-convex lens;The laser source 1, collimator 2, compressor 3, multimode coreless optical fiber 4 and power detector 5 of this embodiment have relatively small structural dimensions. After the above laser source 1, collimator 2, compressor 3, multimode coreless optical fiber 4 and power detector 5 are installed on the housing, the specific size of the light sheet tilted light ray fluorescence chemical sensor is similar to some handheld instruments. It can be understood that compared with the existing expensive and bulky detection equipment, this embodiment has a simple structure and is easy to carry. It does not require specialized personnel to take samples and transfer samples, and can achieve the same detection effect as the existing detection equipment, and can achieve a fast and efficient screening and detection effect of on-site video pollutants. ;
[0045] In one embodiment, the present embodiment uses a multimode coreless optical fiber 4 as a main sensing waveguide, and the sensing region uses a sensing area 41 to improve sensitivity, such as Figure 1 As shown in FIG. 1 , the sensing area 41 is located in the middle section of the multimode coreless optical fiber 3. It can be understood that the multimode coreless optical fiber 4 includes not only the sensing area 41, but also original areas (not shown in the figure) located at both ends of the sensing area 41, wherein the original area is a uniform and unmodified multimode coreless optical fiber. The light propagation along the uniform and unmodified multimode coreless optical fiber can be simply described by ray optics approximation, as shown in FIG. Figure 7 As shown in FIG. 1 , the figure shows the path of the light sheet in the original area of the multimode coreless optical fiber 4. However, if the waveguide diameter (which can be directly regarded as the optical fiber diameter here) is equivalent to or smaller than the wavelength of the light, wave optics (Maxwell's equations) must be used. The light sheet of this embodiment enters the multimode coreless optical fiber 4 at a preset tilt angle, and the light sheet tilts the light rays propagating in the multimode coreless optical fiber 4. The design significance is: Figure 2 As shown, the light sheet oblique light rays do not intersect the axis of the waveguide. When the meridian rays are reflected from the curved waveguide interface, they can be given a preset deflection. The resulting light sheet oblique light rays can be mathematically described using two angles relative to the waveguide-external interface observed from the longitudinal and transverse angles. After propagating for a certain distance, the light sheet oblique light rays will spread radially and form spiral light rays, such as Figure 3 As shown; the sensing system will use a linearly polarized laser source 1 and a collimator 2 and a compressor 3 to inject the tilted light sheet into the incident end face of a section of multimode coreless optical fiber 4 (see Figure 3 A tilted light sheet (a) can generate a narrower range of helical light angles, and the helical light used as pump light greatly increases the number of total internal reflections (see Figure 3b and c), thereby increasing the overlapping area between the evanescent field of the pump light and the fluorescent material layer 43, thereby enhancing the fluorescence intensity; wherein, the light sheet enters the multi-mode coreless optical fiber 4 at a preset tilt angle, and the optimal angle at which the light sheet tilted light ray enters the multi-mode coreless optical fiber can be adjusted and determined through experiments, and then the adjusted and determined angle of the light sheet tilted light ray entering the multi-mode coreless optical fiber is fixed, so that each time the light sheet tilted light ray fluorescent chemical sensor of this embodiment is used to detect the liquid to be tested, the light sheet tilted light ray can enter the multi-mode coreless optical fiber 4 at the adjusted and determined angle. Of course, in order to facilitate the light sheet to be tilted at a preset angle Entering into the multi-mode coreless optical fiber 4, the present embodiment is further provided with a dimming mechanical platform, and the dimming mechanical platform is arranged on the shell and located on one side of the compressor 3. Specifically, viewed along the propagation direction of the laser source 1, the dimming mechanical platform is located after the compressor 3. Through the dimming mechanical platform, the present embodiment can control the incident angle of the light sheet on the optical fiber end face of the multi-mode coreless optical fiber 4 to form a light sheet tilted light ray propagating in the multi-mode coreless optical fiber 4. The dimming mechanical platform can include an electric rotating stage 11 and a three-axis electric translation stage 12, or it can be other structures, as long as it can control the light sheet to form a light sheet tilted light ray propagating in the multi-mode coreless optical fiber 4.
[0046] In one embodiment, for the sensing area 41 composed of multiple cavities and each of which has a different diameter, this embodiment specifically develops three sensing area 41 structures, wherein the sensing area 41 can be a conical sensing area 41, such as Figure 4 As shown, the conical sensing area 41 is realized by heating and stretching the multimode coreless optical fiber 4, wherein the conical sensing area 41 includes a first cylinder, a first conical cylinder, a second cylinder, a second conical cylinder and a third cylinder connected in sequence, wherein the end of the first conical cylinder with a larger area is connected to the first cylinder and the other end is connected to the second cylinder, the end of the second conical cylinder with a smaller area is connected to the second cylinder and the other end is connected to the third cylinder, and the diameter of the second cylinder is smaller than the diameter of the first cylinder and the diameter of the third cylinder. On the basis of this shape, the geometric shape of the sensing area 41, such as the waist diameter, length and taper, can be precisely controlled to make the propagated spiral light rays overlap with the fluorescent material layer 43 in the form of a stronger evanescent field for effective fluorescence generation and collection. A coherent light source will be used to achieve good spectral overlap and minimize unnecessary interference; the sensing area 41 can also be a cylindrical sensing area 41, such as Figure 5As shown, the cylindrical sensing area 41 includes a fourth cylinder, a fifth cylinder and a sixth cylinder connected in sequence, and the diameter of the fifth cylinder is larger than that of the fourth cylinder and the sixth cylinder. Based on this shape, the diameter and length of the central section of the multi-mode coreless optical fiber 4 can be controlled to find the optimal conditions for fluorescence enhancement and collection; the sensing area 41 can also be a microbubble sensing area 41, such as Figure 6 As shown, the microbubble sensing area 41 includes a seventh column, a ring body and an eighth column connected in sequence, the ring body is an annular hollow waveguide structure, the diameter of the annular body is larger than the seventh column and the eighth column, and the annular hollow waveguide structure confines light in a narrow channel, thereby enhancing the intensity of the evanescent field.
[0047] In one embodiment, the light sheet tilted light ray fluorescence chemical sensor further comprises a polarizer 6, such as Figure 1 As shown, the polarizer 6 is a polarization beam splitter, which is arranged in the shell, the input end of the polarizer 6 is connected to the output end of the collimator 2, and the output end of the polarizer 6 is connected to the input end of the compressor 3. The polarizer 6 is used to split the output laser into two, one beam is used for sensing, and the other beam is used for reference, to ensure that the recorded signal data is the same as the laser output power recorded at any point in time.
[0048] In one embodiment, the light sheet tilted light ray fluorescence chemical sensor further comprises a photodetector 7, such as Figure 1 As shown, the photodetector 7 is a reference photodetector 7, which is arranged in the shell. The input end of the photodetector 7 is connected to the output end of the polarizer 6, and thus connected to the output end of the collimator 2. Since the output power of the output laser of the laser will have a certain drift, this embodiment corrects the output power of the output laser of the laser by setting the photodetector 7, thereby maintaining the stability of the output power of the output laser.
[0049] In one embodiment, the light sheet tilted light ray fluorescence chemical sensor further comprises a rotator 8, such as Figure 1 As shown, the rotator 8 is a half-wave plate, and the rotator 8 is arranged in the shell. The input end of the rotator 8 is connected to the output end of the collimator 2, and the output end of the rotator 8 is connected to the input end of the compressor 3. The rotator 8 of this embodiment is used in the scenario where the output laser of the laser has a specific polarization state, such as linear polarized light, then the rotator 8 is needed to change the polarization state of the output laser. If the output laser has polarization states in all directions, then the rotator 8 of this embodiment is not needed.
[0050] In one embodiment, the light sheet tilted light ray fluorescence chemical sensor further comprises a long pass filter 9, such as Figure 1As shown, the long-pass filter 9 is arranged in the shell and is located on the side of the multi-mode coreless optical fiber 4 close to the sensing area 41. The output end of the long-pass filter 9 is connected to the input end of the power detector 5. The long-pass filter 9 is for fluorescence power detection. Since the generated fluorescence wavelength is greater than the laser output wavelength of the laser, the long-pass filter 9 is used to ensure that the energy received by the power detector 5 comes from the fluorescence.
[0051] In one embodiment, the light sheet tilted light ray fluorescence chemical sensor further comprises an integrating sphere 10, such as Figure 1 As shown, the integrating sphere 10 is arranged in the shell, the input end of the integrating sphere 10 is connected to the output end of the long-pass filter 9, and the output end of the integrating sphere 10 is connected to the input end of the power detector 5, which is used to enable the power detector 5 to receive all the fluorescence, thereby minimizing the fluorescence loss.
[0052] In one embodiment, femtosecond laser micromachining technology can be applied to the fabrication of an array of nanocavities 44 on the surface of an optical fiber for carrying metal nanoparticles. Each nonlinear absorption in the interaction of the femtosecond laser with the transparent glass material and the rapid ionization inside the bulk material lead to thermally induced defect formation, material densification / rarefaction or material ablation. The extent of this processing is determined by many factors, such as wavelength, pulse energy, focal size, intensity / phase distribution, pulse width, pulse repetition rate, translation speed, writing direction, writing depth and polarization.
[0053] The probability of each nonlinear absorption process (multiphoton absorption and tunnel ionization) in the interaction of femtosecond laser with transparent materials can be determined from the Keldysh parameters:
[0054]
[0055] where ω is the laser frequency, I is the laser intensity, me is the electron effective mass, e is the elementary electron charge, c is the speed of light, n is the linear refractive index, ε0 is the dielectric constant of free space, and Eg is the band gap of the material. When Υ is much larger or smaller than 1, multiphoton absorption (tunnel ionization) dominates. For Υ≈1, absorption (photoionization) is caused by a combination of two processes. For waveguides in glass, Υ is typically about 1.
[0056] In summary, the present embodiment provides a light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining, wherein the light sheet tilted light ray fluorescence chemical sensor comprises a shell, a laser source 1, a collimator 2, a compressor 3, a multi-mode coreless optical fiber 4 and a power detector 5, wherein the laser source 1, the collimator 2 and the compressor 3 are all arranged in the shell, the multi-mode coreless optical fiber 4 and the power detector 5 are arranged on the shell, the output end of the laser source 1 is connected to the input end of the collimator 2, and the output end of the collimator 2 is connected to the input end of the compressor 3; when the output laser of the laser source 1 enters the multi-mode coreless optical fiber 4 through the collimator 2 and the compressor 3, the output laser forms a light sheet through the compressor 3, and controls the incident angle of the light sheet on the optical fiber end face of the multi-mode coreless optical fiber 4, and enters the multi-mode coreless optical fiber 4 at a preset tilt angle, so as to tilt the light sheet at the multi-mode coreless optical fiber 4. The multimode coreless optical fiber 4 propagates in the coreless optical fiber 4; the multimode coreless optical fiber 4 includes a sensing area 41 composed of multiple sections of cavities, and the diameters corresponding to the multiple sections of cavities are all different. For example, the multiple sections of cavities are assumed to be three sections of cavities, and the diameter of the cavity in the middle is different from the diameters of the cavities at the front and rear ends. In this embodiment, by setting the sensing area 41 composed of multiple sections of cavities and the diameters corresponding to the multiple sections of cavities are all different in the multimode coreless optical fiber 4, the light sheet tilted light rays entering the sensing area 41 can be caused to penetrate the core-cladding boundary due to the sudden change of the waveguide geometry in the multiple sections of the cavity (for example, the waveguide diameter becomes smaller), and interact with the outside in the form of an evanescent field. The smaller the waveguide diameter, the more evanescent fields are generated, similar to the resistance of a water pipe. A stronger evanescent field means more pump light (when the laser is used to excite fluorescence, it is called pump light) to pump the fluorophore to excite fluorescence, thereby enhancing the fluorescence intensity. See Figure 3In figure a, a plurality of metal nanoparticle layers 42 are arranged on the sensing area 41, and the outer layer of the metal nanoparticle layer 42 is covered with a fluorescent material layer 43. For example, a fluorescent material layer 43 such as a monoclonal antibody (FB1 molecule labeled with fluorescein isothiocyanate, FB1-FITC molecule) is used to coat the metal nanoparticle layer 42. The metal nanoparticles of the metal nanoparticle layer 42 are kept at a certain distance from the fluorescent molecules of the fluorescent material layer 43, which can further enhance the fluorescence intensity. Since the light sheet tilted light ray fluorescent chemical sensor must be flushed each time the liquid to be tested is detected to prevent affecting the next detection result; in order to prevent the metal nanoparticles of the metal nanoparticle layer 42 from being flushed away, the present embodiment uses a femtosecond laser micromachining system to accurately modify the plurality of metal nanoparticle layers 42. The surface of the coreless optical fiber 4 is formed to establish a nanocavity 44 array. It can be understood that the sensing area 41 is provided with a plurality of nanocavities 44 by femtosecond laser micromachining, and each nanocavity 44 is filled with a metal nanoparticle layer 42, which is used to physically protect the metal nanoparticle layer 42 after the metal nanoparticle layer 42 is attached to the nanocavity 44, and provides a perfect solution to the problem that the metal nanoparticle layer 42 is easily washed away, protects the metal nanoparticle layer 42 from external influences, and improves the long-term stability and repeatable practicality of the light sheet tilted light ray fluorescence chemical sensor, and the nanocavity 44 is filled with The nanoparticle layer will produce localized surface plasmon resonance, which can further enhance the fluorescence intensity. The type and shape of the metal nanoparticle layer 42 used can be changed. For example, the type can be a gold nanoparticle layer or a silver nanoparticle layer, and the shape can be a spherical particle layer or a rod-shaped particle layer. When the light sheet tilted light ray fluorescence chemical sensor of this embodiment is needed to detect the liquid to be tested, the sensing area 41 of the multimode coreless optical fiber 4 is first placed in the liquid to be tested, and a stable output laser is output through the laser source 1 of this embodiment. After the output laser passes through the collimator 2, the output laser is converted into a flat The parallel laser then passes through the compressor 3 to form a light sheet at the focus, and the incident angle of the light sheet on the optical fiber end face of the multi-mode coreless optical fiber 4 is controlled to form a preset inclined light sheet. The inclined light rays propagate in the multi-mode coreless optical fiber 4, and the fluorescence is absorbed by the fluorescent material in the sensing area 41 of the multi-mode coreless optical fiber 4, and then the fluorescence power of the liquid to be tested is specifically detected by the power detector 5, and the pollutant concentration is determined by the fluorescence power, and then the food safety quality of the liquid to be tested is determined; wherein, the laser source 1 is a polarized laser source 1, the collimator 2 is a plano-convex lens collimator 2, and the compressor 3 is a cylindrical plano-convex lens;The laser source 1, collimator 2, compressor 3, multimode coreless optical fiber 4 and power detector 5 of this embodiment have relatively small structural dimensions. After the above laser source 1, collimator 2, compressor 3, multimode coreless optical fiber 4 and power detector 5 are installed on the housing, the specific size of the light sheet tilted light ray fluorescence chemical sensor is similar to some handheld instruments. It can be understood that compared with the existing expensive and bulky detection equipment, this embodiment has a simple structure and is easy to carry. It does not require specialized personnel to take samples and transfer samples, and can achieve the same detection effect as the existing detection equipment, and can achieve a fast and efficient screening and detection effect of on-site video pollutants. ;
[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. Fluorescent chemical sensor based on light sheet tilted light rays processed by femtosecond laser micromachining, It is characterized in that include: case; A laser source is disposed in the housing and is used to output laser light; A collimator is arranged in the housing, the input end of the collimator is connected to the output end of the laser source, and the collimator is used to convert the output laser into parallel laser; A compressor is disposed in the housing, an input end of the compressor is connected to an output end of the collimator, and the compressor is used to form a light sheet at a focus of the parallel laser light; A multimode coreless optical fiber is arranged on the housing at one side of the compressor, wherein when the output laser of the laser source enters the multimode coreless optical fiber through the collimator and the compressor, the output laser enters the multimode coreless optical fiber at a preset tilt angle; The multimode coreless optical fiber comprises a sensing area composed of multiple cavities, and the diameters corresponding to the multiple cavities are different. The sensing area is provided with multiple nanocavities by femtosecond laser micromachining, each nanocavity is filled with a metal nanoparticle layer, and the outer layer of the metal nanoparticle layer is covered with a fluorescent material layer; A power detector is arranged on the housing, connected to the multi-mode coreless optical fiber, and used for detecting fluorescence power.
2. The light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining according to claim 1, It is characterized in that The sensing area is a conical sensing area, wherein the conical sensing area includes a first column, a first conical column, a second column, a second conical column and a third column which are connected in sequence.
3. The light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining according to claim 1, It is characterized in that The sensing area is a columnar sensing area, wherein the columnar sensing area includes a fourth column, a fifth column and a sixth column connected in sequence, and the diameter of the fifth column is larger than that of the fourth column and the sixth column.
4. The light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining according to claim 1, It is characterized in that The sensing area is a microbubble sensing area, wherein the microbubble sensing area includes a seventh column, an annular body and an eighth column connected in sequence, and the diameter of the annular body is larger than that of the seventh column and the eighth column.
5. The light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining according to claim 1, It is characterized in that The light sheet tilted light ray fluorescence chemical sensor further comprises: A polarizer is arranged in the housing, the input end of the polarizer is connected to the output end of the collimator, the output end of the polarizer is connected to the input end of the compressor, and the polarizer is used to split the output laser into two.
6. The light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining according to claim 5, It is characterized in that The light sheet tilted light ray fluorescence chemical sensor further comprises: A photoelectric detector is arranged in the housing, an input end of the photoelectric detector is connected to an output end of the collimator, and the photoelectric detector is used to correct the drift of the output power of the output laser.
7. The light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining according to claim 1, It is characterized in that The light sheet tilted light ray fluorescence chemical sensor further comprises: A rotator is arranged in the shell, the input end of the rotator is connected to the output end of the collimator, the output end of the rotator is connected to the input end of the compressor, and the rotator is used to change the polarization state of the output laser.
8. The light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining according to claim 1, It is characterized in that The light sheet tilted light ray fluorescence chemical sensor further comprises: The dimming mechanical platform is arranged on the housing and is used to control the incident angle of the light sheet transmitted into the multi-mode coreless optical fiber. The multi-mode coreless optical fiber is arranged on the dimming mechanical platform.
9. The light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining according to claim 1, It is characterized in that The light sheet tilted light ray fluorescence chemical sensor further comprises: A long-pass filter is arranged in the housing and is located on a side of the multi-mode coreless optical fiber close to the sensing area. The output end of the long-pass filter is connected to the input end of the power detector. The long-pass filter is used to ensure that the energy received by the power detector comes from the fluorescence.
10. The light sheet tilted light ray fluorescence chemical sensor based on femtosecond laser micromachining according to claim 1, It is characterized in that The light sheet tilted light ray fluorescence chemical sensor further comprises: An integrating sphere is arranged in the housing, an output end of the integrating sphere is connected to an input end of the power detector, and the integrating sphere is used to enable the power detector to receive all the fluorescence.