Single-camera dual-color plif measurement apparatus and measurement method

Abstract

This invention discloses a single-camera dual-color PLIF measurement device and method. The invention integrates an imaging lens, a beam splitting and filtering module, a first reflection adjustment module, a second reflection adjustment module, and an image combining module into a single optical device. This device, combined with a first laser and a single camera, forms a single-camera dual-color PLIF measurement device. This device can measure the fluorescence signal-temperature relationship curve in the working fluid under test, and thus infer the temperature distribution at the measurement location based on the fluorescence signal obtained by the camera. This device reduces the difficulty and complexity of optical adjustment, making the adjustment and use of the optical measurement part more convenient. After the device is adjusted, the deviation between the two images presented by the camera is minimal, eliminating the need for a dedicated algorithm to correct and match the two images. The dual-color laser-induced fluorescence measurement device has a high degree of integration and can use a wider range of optical magnifications compared to products currently offered by commercial measurement manufacturers.

Description

Technical Field

[0001] This invention relates to the field of fluid temperature field measurement technology, and more specifically, to a single-camera dual-color PLIF measurement device and method. Background Technology

[0002] In thermal fluid experiments, laser-induced fluorescence (LAF) can be used to measure the fluid's temperature field without interference (laser excitation of fluorescence, with a direct correlation between fluorescence intensity and temperature). This method typically uses a single fluorescent substance as the thermometric agent to indirectly measure the fluid's temperature field. However, this method has limited temperature sensitivity, and many other factors (such as fluorescent substance concentration, spatial distribution of laser intensity, spatial angle, and temporal stability of laser intensity) can affect the accuracy of temperature measurements. To improve the LAF method and enhance its sensitivity and anti-interference capabilities, a dual-color LAF method can be used. This involves using two fluorescent dyes, each excited separately by a laser. By analyzing the fluorescence intensity-temperature relationship between different fluorescent agents and performing ratio processing or other methods, a new fluorescence signal-temperature relationship can be obtained. This improves the sensitivity of temperature measurements, reduces its dependence on other factors, and enhances the method's anti-interference capabilities.

[0003] However, the implementation of the two-color laser-induced method requires various optical components such as lasers, filters, cameras, and lenses. Currently, experimental practices often employ decentralized devices to achieve this. A typical experimental setup requires at least two cameras and matching lenses, along with additional synchronization control to manage and operate the entire system. Therefore, existing devices necessitate multiple camera lenses, dispersed optical components, and complex on-site calibration. Maintaining the applicability of the calibration relationships during implementation significantly increases the complexity of the measurement method, leading to substantial time and material costs for the experiment. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the objective of this invention is to propose a single-camera dual-color PLIF measurement device and method. This invention integrates the optical measurement components into a single unit, reducing the difficulty and complexity of optical adjustment, thus making the adjustment and use of the optical measurement components more convenient. By combining a spectral filtering module, a first reflection adjustment module, a second reflection adjustment module, and an image combining module, a spectral splitting and image adjustment module is formed. Only one set of camera and imaging lens is needed to generate dual images of different spectral bands required for dual-color PLIF. After the device is adjusted, the deviation between the dual images presented by the camera is minimal, eliminating the need for a dedicated algorithm to correct and match the dual images. The dual-color laser-induced fluorescence measurement device of this invention has a high degree of integration and can use a wider range of optical magnifications compared to products currently offered by commercial measurement manufacturers.

[0005] In a first aspect, the present invention provides a single-camera dual-color PLIF measurement device. According to an embodiment of the present invention, the single-camera dual-color PLIF measurement device includes:

[0006] A first laser is used to excite two fluorescent agents contained in a first test medium to generate two types of fluorescence.

[0007] An imaging lens, wherein two types of fluorescence excited by the first laser enter the imaging lens for imaging;

[0008] The beam splitting and image splitting adjustment module includes a beam splitting filter module, a first reflection adjustment module, a second reflection adjustment module, and an image combining module. Light rays exiting the imaging lens are split into a first ray and a second ray after passing through the beam splitting filter module, and the wavelength of the first ray is greater than the wavelength of the second ray. The first ray passes through the first reflection adjustment module and then to the image combining module, and the second ray passes through the second reflection adjustment module and then to the image combining module.

[0009] A camera, used to image the first light ray and the second light ray passing through the image combining module, respectively.

[0010] According to the single-camera dual-color PLIF measurement device of the above embodiments of the present invention, firstly, the optical measurement part is integrated into a whole, reducing the difficulty and complexity of optical adjustment, thereby making the adjustment and use of the optical measurement part more convenient; secondly, by combining the spectral filtering module, the first reflection adjustment module, the second reflection adjustment module, and the image combining module, a spectral splitting and image adjustment module is formed, requiring only one set of camera and imaging lens combination to generate dual images of different spectral bands required for dual-color PLIF; thirdly, after the device is adjusted, the deviation between the dual images presented by the camera is extremely small, and no special algorithm is required to correct and match the dual images; fourthly, the dual-color laser-induced fluorescence measurement device of the present invention has a high degree of integration and can use a wider range of optical magnifications than products currently provided by commercial measurement manufacturers.

[0011] In addition, the single-camera dual-color PLIF measuring device according to the above embodiments of the present invention may also have the following additional technical features:

[0012] In some embodiments of the present invention, the first laser includes a first sub-laser and a second sub-laser.

[0013] In some embodiments of the present invention, the device further includes: a first laser beam combiner module, which is used to combine the laser emitted by the first sub-laser and the laser emitted by the second sub-laser.

[0014] In some embodiments of the present invention, the device further includes: a first beam splitting module and a first laser energy meter, wherein the first beam splitting module is disposed in the optical path between the first laser beam combiner module and the first working medium to be tested, and the first laser energy meter is disposed on the laser path split by the first beam splitting module.

[0015] In some embodiments of the present invention, the device further includes: a first optical component, the first optical component being disposed in the optical path between the first beam splitting module and the first working medium to be tested.

[0016] In some embodiments of the present invention, the lens further includes: an aperture controller disposed at one end of the imaging lens near the first working medium to be measured; and / or, it further includes: an adjustable slit disposed at one end of the imaging lens near the beam splitting and imaging adjustment module.

[0017] In some embodiments of the present invention, the invention further includes: a first adapter connected between the adjustable slit and the beam splitting and imaging adjustment module; and / or, it further includes: a second adapter connected between the beam splitting and imaging adjustment module and the camera.

[0018] In some embodiments of the present invention, the beam-splitting filter module is provided with a long-wavelength pass short-wavelength reflector; and / or, the first reflection adjustment module is provided with a first reflector; and / or, the second reflection adjustment module is provided with a second reflector; and / or, the image combining module is provided with a long-wavelength reflector short-wavelength pass; and / or, the camera is provided with a photosensitive component.

[0019] In some embodiments of the present invention, the beam splitting and image adjustment module further includes a long-pass filter and a first narrowband trap, wherein the long-pass filter and the first narrowband trap are respectively disposed between the long-pass short-wave reflection beam splitter and the first reflector; and / or, the beam splitting and image adjustment module further includes a band-pass wavepass filter and a second narrowband trap, wherein the band-pass wavepass filter and the second narrowband trap are respectively disposed between the long-pass short-wave reflection beam splitter and the second reflector.

[0020] In some embodiments of the present invention, the first test medium includes a first fluorescent agent and a second fluorescent agent, wherein the fluorescence intensity of the first fluorescent agent is positively correlated with temperature and the fluorescence intensity of the second fluorescent agent is negatively correlated with temperature; or, the fluorescence intensity of the first fluorescent agent is positively correlated with temperature and the fluorescence intensity of the second fluorescent agent is uncorrelated with temperature; or, the fluorescence intensity of the first fluorescent agent is negatively correlated with temperature and the fluorescence intensity of the second fluorescent agent is uncorrelated with temperature.

[0021] In some embodiments of the present invention, a principle verification device is further included, which is used to determine the light intensity of the first laser, the types and concentrations of the two phosphors in the first working fluid to be tested, and the principle verification device includes: a second laser, a second laser beam combiner module, a second beam splitter module, a second laser energy meter, a second optical component, a second working fluid to be tested, a fluorescence receiving module, and a spectrometer. The second laser includes a third sub-laser and a fourth sub-laser. The second laser beam combiner module is used to combine the laser emitted by the third sub-laser and the laser emitted by the fourth sub-laser. The second beam splitter module, the second optical component, and the second working fluid to be tested are sequentially arranged in the optical path of the combined laser beam. The second laser energy meter is arranged on the laser path split by the second beam splitter module. The second working fluid to be tested generates two types of fluorescence under the excitation of the laser emitted by the second optical component. The fluorescence receiving module includes a focusing lens and a third narrowband trap. The fluorescence generated by the second working fluid to be tested passes sequentially through the focusing lens and the third narrowband trap. The fluorescence receiving module and the spectrometer are connected by an optical fiber.

[0022] In a second aspect, the present invention provides a method for measuring the temperature field of a fluid using the single-camera dual-color PLIF measurement device described in the above embodiments. According to an embodiment of the present invention, the method includes:

[0023] (1) Determine the light intensity of the first laser, the types and concentrations of the two fluorescent agents in the first working medium to be tested;

[0024] (2) Activate the first laser to excite the first working fluid to produce two types of fluorescence;

[0025] (3) The two types of fluorescence pass through the imaging lens. The light rays coming out of the imaging lens are dispersed into a first light ray and a second light ray after passing through the beam splitting and filtering module. The first light ray passes through the first reflection adjustment module and then to the image combining module. The second light ray passes through the second reflection adjustment module and then to the image combining module. The camera is used to image the first light ray and the second light ray that have passed through the image combining module respectively, so as to obtain the fluorescence signal.

[0026] (4) Change the temperature of the first working fluid to be tested, and measure the fluorescence signal of the first working fluid to be tested at different specific temperatures according to the method of step (3) so as to obtain the fluorescence signal-temperature relationship curve of the first working fluid to be tested;

[0027] (5) Based on the fluorescence signal-temperature relationship curve, the temperature distribution at the measurement location is inferred from the fluorescence signal obtained by the camera.

[0028] According to the above embodiments of the present invention, the method for measuring the temperature field of a fluid employs a single-camera dual-color PLIF measurement device that integrates the optical measurement components into a single unit. This reduces the difficulty and complexity of optical adjustment, making the adjustment and use of the optical measurement components more convenient. The method uses a spectral splitting and imaging adjustment module formed by combining a spectral filtering module, a first reflection adjustment module, a second reflection adjustment module, and an image combining module. Only one set of camera and imaging lens is needed to generate dual images of different spectral bands required for dual-color PLIF. After adjustment, the deviation between the dual images presented by the camera is minimal, eliminating the need for a dedicated algorithm to correct and match the dual images. The dual-color laser-induced fluorescence measurement device used in this method has a high degree of integration and can use a wider range of optical magnifications compared to products currently offered by commercial measurement manufacturers.

[0029] In addition, the method according to the above embodiments of the present invention may also have the following additional technical features:

[0030] In some embodiments of the present invention, step (1) includes the following steps: starting the second laser to excite the second working medium containing any two fluorescent agents to generate two types of fluorescence; passing the two types of fluorescence sequentially through a focusing lens and a third narrow-band trap, and entering the spectrometer; obtaining the fluorescence intensity-laser irradiation relationship curve of the two fluorescent agents based on the change of fluorescence intensity over time, so as to select the appropriate light intensity of the second laser, the type of fluorescent agent, and the concentration.

[0031] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0032] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0033] Figure 1 This is a schematic diagram of a single-camera dual-color PLIF measurement device according to an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of a principle verification device according to an embodiment of the present invention;

[0035] Figure 3 This is a flowchart of a method for measuring the temperature field of a fluid using a single-camera dual-color PLIF measuring device according to an embodiment of the present invention.

[0036] Attached image captions:

[0037] 100-First working medium under test, 200-Aperture controller, 300-Imaging lens, 400-Adjustable slit, 500-First adapter, 600-Spectrophotometer and image splitting adjustment module, 610-Spectrophotometer and filter module, 611-Long-pass short-pass reflector spectrophotometer, 620-First reflection adjustment module, 621-First reflector, 630-Second reflection adjustment module, 631-Second reflector, 640-Image combining module, 641-Long-pass short-pass reflector spectrophotometer, 650-Long-pass filter, 660-Bandpass filter, 700-Second adapter, 800-Camera, 810-Photosensitive component, 910-First... Sub-laser, 920-Second sub-laser, 930-First laser beam combiner module, 940-First beam splitter module, 950-First laser energy meter, 960-First optical component, 1000-Principle verification device, 1100-Third sub-laser, 1200-Fourth sub-laser, 1300-Second laser beam combiner module, 1400-Second beam splitter module, 1500-Second laser energy meter, 1600-Second optical component, 1700-Second working medium under test, 1800-Fluorescence receiving module, 1801-Third narrowband trap, 1802-Focusing lens, 1900-Spectrometer. Detailed Implementation

[0038] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the elements referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0041] In this invention, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0043] In one aspect of the invention, a single-camera dual-color PLIF measurement device is provided, as shown in the attached diagram. Figure 1 The single-camera dual-color PLIF measurement device includes: a first laser; an imaging lens 300; a beam splitting and image splitting adjustment module 600, which includes a beam splitting filter module 610, a first reflection adjustment module 620, a second reflection adjustment module 630, and an image combining module 640; and a camera 800. The single-camera dual-color PLIF measurement device proposed in this invention will be described in detail below with reference to the accompanying drawings.

[0044] In an embodiment of the present invention, a first laser is used to excite two fluorescent agents contained in the first test medium 100 to produce two types of fluorescence. Further, refer to the appendix... Figure 1 The first laser includes a first sub-laser 910 and a second sub-laser 920. The first sub-laser 910 and the second sub-laser 920 emit lasers of two different intensities, which are used to excite two different fluorescent agents to produce two different fluorescences. It should be noted that different fluorescent agents require lasers of different intensities for excitation; for example, Rhodamine B fluorescent staining agent corresponds to a 532nm laser, and sodium fluorescein corresponds to a 477nm laser.

[0045] In embodiments of the present invention, reference is made to the appendix. Figure 1 The device further includes a first laser beam combiner module 930, which is used to combine the laser emitted by the first sub-laser 910 and the laser emitted by the second sub-laser 920. Further, refer to the appendix... Figure 1 The device further includes a first beam splitter module 940 and a first laser energy meter 950. The first beam splitter module 940 is disposed in the optical path between the first laser beam combiner module 930 and the first working medium 100 under test. The first beam splitter module 940 is used to split a small proportion of the laser beam, which is then projected to the first laser energy meter 950, while a large proportion of the laser beam is reflected to the first optical component 960. The first laser energy meter 950 is disposed on the laser path split by the first beam splitter module 940 and is used to detect the power stability of the combined laser beam. Further, refer to the attached diagram. Figure 1 The device also includes a first optical component 960 (e.g., a sheet light lens), which is disposed in the optical path between the first beam splitting module 940 and the first working medium under test 100 to form sheet light after beam combining.

[0046] In an embodiment of the present invention, the first working fluid to be tested 100 may be placed in a transparent cuvette.

[0047] In embodiments of the present invention, reference is made to the appendix. Figure 1 Imaging lens 300 is used to image the object being imaged (i.e., the working medium containing the fluorescent agent), and can be a commercial lens or a self-assembled lens.

[0048] Further, see Appendix Figure 1 The device also includes an aperture controller 200, which is located at the end of the imaging lens 300 near the first working medium 100 to be tested, and is used to adjust the amount of light entering the imaging lens 300. The imaging depth of field can be adjusted by adjusting the aperture controller 200.

[0049] Further, see Appendix Figure 1 The device also includes an adjustable slit 400, which is located at one end of the imaging lens 300 near the beam splitting and image adjustment module 600 and is used to adjust the imaging range.

[0050] In embodiments of the present invention, reference is made to the appendix. Figure 1 The beam splitting and imaging adjustment module 600 includes a beam splitting filter module 610, a first reflection adjustment module 620, a second reflection adjustment module 630, and an image combining module 640. Light rays exiting the imaging lens 300 are split into a first ray and a second ray after passing through the beam splitting filter module 610, with the wavelength of the first ray being greater than that of the second ray. The first ray passes through the first reflection adjustment module 620 and then to the image combining module 640, while the second ray passes through the second reflection adjustment module 630 and then to the image combining module 640. Optionally, the four sub-modules included in the beam splitting and imaging adjustment module 600 are integrated into one unit.

[0051] Further, see Appendix Figure 1The spectrophotometer filter module 610 includes a long-wavelength pass-short-wavelength reflector spectrophotometer 611. This ensures that long-wavelength fluorescence (i.e., the first ray) can be transmitted, while short-wavelength fluorescence (i.e., the second ray) is reflected or absorbed. (See attached reference.) Figure 1 The first reflection adjustment module 620 includes a first reflector 621, used to reflect the first light rays to the image combining module 640. (See attached image.) Figure 1 The second reflection adjustment module 630 includes a second reflector 631, used to reflect the second light rays to the image combining module 640. (See attached image.) Figure 1 The image combining module 640 includes a long-wavelength anti-short-wavelength spectrophotometer 641. This spectrophotometer ensures that the long-wavelength fluorescence (i.e., the first ray) is reflected or absorbed, while the short-wavelength fluorescence (i.e., the second ray) is transmitted, thereby achieving the purpose of combining the first and second rays. (See attached image.) Figure 1 To illustrate, let's take the arrow in the imaged object as an example. During imaging, the arrow passes through the imaging lens 300, and the light enters the beam splitting and imaging module. The light rays above a certain beam splitting threshold (i.e., the first light ray) form one image, and the light rays below the certain beam splitting threshold (i.e., the second light ray) form another image.

[0052] Optionally, the long-wavelength-to-short-wavelength-reflection spectrophotometer 611 is fixed in the spectrophotometer-filtering module 610 via a 45-degree lens bracket. Optionally, the long-wavelength-to-short-wavelength-reflection spectrophotometer 641 is fixed in the image-combining module 640 via a 45-degree lens bracket. Optionally, the first reflector 621 is mounted in the first reflection adjustment module 620 via an adjustable-angle lens bracket; optionally, the second reflector 631 is mounted in the second reflection adjustment module 630 via an adjustable-angle lens bracket, thereby adjusting the imaging distance (i.e., the distance between the first and second rays) Figure 1 (The distance between the two arrow images in camera 800).

[0053] Further, see Appendix Figure 1 The beam splitting and imaging adjustment module 600 also includes a long-pass filter 650 and a first narrowband trap (not shown in the figure). The long-pass filter 650 and the first narrowband trap are respectively disposed between the long-pass short-wave reflection beam splitter 611 and the first reflector 621. The function of the long-pass filter 650 is to ensure that long-wave fluorescence passes through while other stray light is filtered out; the function of the first narrowband trap is to filter out the laser peak generated by the first laser in the fluorescence doping.

[0054] Further, see Appendix Figure 1The beam splitting and imaging adjustment module 600 also includes a bandpass filter 660 and a second narrowband trap (not shown in the figure). The bandpass filter 660 and the second narrowband trap are respectively disposed between the long-pass short-wave reflection beam splitter 611 and the second reflector 631. The function of the bandpass filter 660 is to ensure that short-wave fluorescence passes through while other stray light is filtered out. The function of the second narrowband trap is to filter out the laser peak generated by the first laser in the fluorescence doping.

[0055] The selection of the first and second narrowband light traps should be based on the first laser wavelength used as the center wavelength, with a recommended bandwidth of 10nm-25nm (e.g., 10nm or 25nm). The bandwidth should be as low as possible to filter out reflected and scattered laser light and stray light, while retaining as much of the center wavelength fluorescence information as possible.

[0056] Further, see Appendix Figure 1 The device also includes a first adapter 500, which is connected between the adjustable slit 400 and the beam splitting and image splitting adjustment module 600, for connecting the imaging lens 300 and the beam splitting and image splitting adjustment module 600 into a single unit. Further, refer to the attached... Figure 1 The device also includes a second adapter 700, which is connected between the beam splitting and imaging adjustment module 600 and the camera 800. The second adapter 700 integrates the beam splitting and imaging adjustment module 600 and the camera 800 into a single unit, thereby integrating the optical measurement components into a single unit. This reduces the difficulty and complexity of optical adjustment and makes the adjustment and use of the optical measurement components more convenient. Simultaneously, the imaging optical magnification can be adjusted by adjusting the imaging lens 300, the first adapter 500, or the second adapter 700.

[0057] Further, see Appendix Figure 1 The camera 800 is used to image the first and second rays from the image fusion module 640, respectively. Furthermore, the camera 800 includes a photosensitive element 810.

[0058] Furthermore, the working fluids of the two fluorescent agents include a first fluorescent agent and a second fluorescent agent. The fluorescence intensity of the first fluorescent agent is positively correlated with temperature, and the fluorescence intensity of the second fluorescent agent is negatively correlated with temperature; or, the fluorescence intensity of the first fluorescent agent is positively correlated with temperature, and the fluorescence intensity of the second fluorescent agent is uncorrelated with temperature; or, the fluorescence intensity of the first fluorescent agent is negatively correlated with temperature, and the fluorescence intensity of the second fluorescent agent is uncorrelated with temperature. By simultaneously using the above two fluorescent agents for ratio processing or other processing methods, a new fluorescence signal-temperature relationship is obtained. This eliminates the influence of factors such as fluorescent substance concentration, laser intensity spatial distribution, spatial angle, and laser intensity temporal stability on the accuracy of temperature measurement, thereby improving the sensitivity of temperature measurement (its sensitivity is improved by 2-5 times), reducing its dependence on other factors, and improving the anti-interference ability of the measurement method. This invention uses a principle verification device to determine the types of the two fluorescent agents.

[0059] As previously mentioned, the concentration, type, and spatial distribution of the fluorescent substance all affect the temperature distribution of the fluorescence. Therefore, when measuring the temperature field of a fluid, it is first necessary to select appropriate concentrations, types, and laser intensities of the fluorescent substance in the first working fluid 100. Therefore, refer to the appendix... Figure 2The device also includes a principle verification device 1000, which is used to determine the light intensity of the first laser, the types and concentrations of the two phosphors in the first test medium 100. The principle verification device 1000 includes a second laser, a second laser beam combiner module 1300, a second beam splitter module 1400, a second laser energy meter 1500, a second optical component 1600, a second test medium 1700, a fluorescence receiving module 1800, and a spectrometer 1900. The second laser includes a third sub-laser 1100 and a fourth sub-laser 1200, which emit two lasers of different intensities to excite the two phosphors to produce two different fluorescences. The second laser beam combiner module 1300 is used to combine the laser emitted by the third sub-laser 1100 and the laser emitted by the fourth sub-laser 1200. The second beam splitter 1400, the second optical component 1600, and the second working medium under test 1700 are sequentially arranged in the optical path of the combined laser beam. The second beam splitter 1400 is used to split a small proportion of the laser beam, and the second laser energy meter 1500 is arranged on the laser path split by the second beam splitter 1400 to detect the power stability of the combined laser beam. The second optical component 1600 is used to form a sheet beam of the combined laser beam. The second working medium under test 1700 generates two types of fluorescence under the excitation of the laser beam from the second optical component 1600. The fluorescence receiving module 1800 includes a focusing lens 1802 and a third narrowband trap 1801. The focusing lens 1802 is used for focusing, and the third narrowband trap 1801 is used to filter out the laser peak generated by the second laser in the fluorescence doping. The fluorescence generated by the second working medium under test 1700 passes sequentially through the focusing lens 1802 and the third narrowband trap 1801. The fluorescence receiving module 1800 and the spectrometer 1900 are connected by optical fiber. Specifically, based on the changes in the integrated values ​​of long-wavelength and short-wavelength fluorescence spectra received by the 1900 spectrometer with laser intensity, fluorescent dye concentration, and temperature, appropriate laser intensity, fluorescent dye type, and concentration were selected. Furthermore, the fluid sample containing the fluorescent dye was irradiated with a laser for an extended period, and the change in fluorescence intensity over time was observed. Based on the change in fluorescence intensity over time, a qualitative curve of the fluorescence intensity-laser irradiation relationship during the quenching process of the fluorescent substance was generated, clarifying the appropriate application range of laser intensity and concentration; ultimately, a suitable experimental configuration was obtained.

[0060] Ultimately, the selection criteria were: a first fluorescent agent whose fluorescence intensity was positively correlated with temperature, plus a second fluorescent agent whose fluorescence intensity was negatively correlated with temperature; a first fluorescent agent whose fluorescence intensity was positively correlated with temperature, plus a second fluorescent agent whose fluorescence intensity was zero-correlated with temperature; or a first fluorescent agent whose fluorescence intensity was negatively correlated with temperature, plus a second fluorescent agent whose fluorescence intensity was zero-correlated with temperature.

[0061] In existing technologies, implementing a two-color laser-induced fluorescence imaging method requires at least two cameras and matching lenses, as well as an additional synchronization control device for operation. Therefore, the optical components of existing devices are scattered, requiring cumbersome on-site calibration and maintaining the applicability of experimental calibration relationships during implementation, significantly increasing the complexity of the measurement method and resulting in substantial time and material costs for experiments. To address these issues, this invention integrates the imaging lens, beam-splitting filter module, first reflection adjustment module, second reflection adjustment module, and image-combining module into a single optical device. This device, combined with a first laser and a single camera, forms a two-color laser-induced fluorescence imaging device, which possesses at least one of the following advantages:

[0062] First, by integrating the optical measurement components into a single unit, the difficulty and complexity of optical adjustment are reduced, making the adjustment and use of the optical measurement components more convenient.

[0063] Second, by combining the spectral filtering module, the first reflection adjustment module, the second reflection adjustment module, and the image combining module, a spectral image adjustment module is formed. Only one set of camera and imaging lens combination is needed to form two images of different spectral bands required for dual-color PLIF.

[0064] Third, after the device is adjusted, the deviation between the two images presented by the camera is minimal, and there is no need for a dedicated algorithm to correct and match the two images;

[0065] Fourth, the dual-color laser-induced fluorescence measurement device of this invention has a high degree of integration and can use a wider range of optical magnifications compared to products currently offered by commercial measurement manufacturers. Specifically, the beam splitting and image separation adjustment module of this invention is located between the imaging lens and the camera, increasing the image distance and allowing for a relatively large optical magnification. Simultaneously, the size of the beam splitting and image separation adjustment module can be made very compact. By selecting a suitable lens, the image distance and object distance can be controlled, thereby reducing the optical magnification. Therefore, the device of this invention can achieve a wider range of optical magnifications, and its product selection is broader. If the beam splitting and image separation adjustment module were placed between the imaging lens and the object, the effect of increasing the image distance would not be achieved.

[0066] In a second aspect, the present invention provides a method for measuring the temperature field of a fluid using the single-camera dual-color PLIF measuring device described in the above embodiments. According to embodiments of the present invention, refer to the appendix... Figure 3 The above methods include:

[0067] S100: Determine the light intensity of the first laser, the types and concentrations of the two fluorescent agents in the first test medium.

[0068] In this step, a principle verification device is used to determine the light intensity of the first laser, the types and concentrations of the two phosphors in the first test medium 100, and specifically includes the following steps:

[0069] The second laser is activated to excite the second analyte containing any two fluorescent agents to produce two types of fluorescence;

[0070] The two fluorescent agents are sequentially passed through a focusing lens and a third narrow-band trap before entering a spectrometer. Based on the change in fluorescence intensity over time, the fluorescence intensity-laser irradiation relationship curves of the two fluorescent agents are obtained, so as to select the appropriate light intensity of the second laser, the type of fluorescent agent, and the concentration.

[0071] Specifically, the third and fourth sub-lasers are activated separately, emitting lasers of different intensities. A second laser beam combiner module combines the lasers emitted by the third and fourth sub-lasers. A second beam splitter module separates a small proportion of the laser beam. A second laser energy meter detects the power stability of the combined laser beam. A second optical assembly forms a sheet beam from the combined laser beam. The working fluid containing the two fluorescent agents generates two types of fluorescence under the excitation of the laser from the second optical assembly. The fluorescence then passes through a focusing lens and a third narrow-band trap before entering a spectrometer. Based on the changes in the integrated values ​​of the long-wavelength and short-wavelength fluorescence spectra received by the spectrometer with laser intensity, fluorescent dye concentration, and temperature, appropriate laser intensity, fluorescent dye type, and concentration are selected. Furthermore, the fluid sample containing the fluorescent dye is irradiated with laser for a prolonged period, and the change in fluorescence intensity over time is observed. Based on the change in fluorescence intensity over time, a qualitative curve of the fluorescence intensity-laser irradiation relationship during the quenching process of the fluorescent substance is given, clarifying the appropriate application range of laser intensity and concentration; ultimately, a suitable experimental configuration is obtained.

[0072] Ultimately, the selection criteria were: a first fluorescent agent whose fluorescence intensity was positively correlated with temperature, plus a second fluorescent agent whose fluorescence intensity was negatively correlated with temperature; a first fluorescent agent whose fluorescence intensity was positively correlated with temperature, plus a second fluorescent agent whose fluorescence intensity was zero-correlated with temperature; or a first fluorescent agent whose fluorescence intensity was negatively correlated with temperature, plus a second fluorescent agent whose fluorescence intensity was zero-correlated with temperature.

[0073] S200: Activate the first laser to excite the first working fluid to produce two types of fluorescence.

[0074] In this step, the first and second sub-lasers are activated, emitting lasers of different intensities. A first laser beam combiner module combines the lasers emitted by the first and second sub-lasers. A first beam splitter module separates a small proportion of the laser beam. A first laser energy meter detects the power stability of the combined laser beam. A first optical component forms a sheet of light from the combined laser beam. The first working medium under test generates two types of fluorescence under the excitation of the laser light exiting the first optical component. It should be noted that the two fluorescent agents contained in the working medium in this step are known types, and the concentrations of the fluorescent agents in the working medium are also known, determined by the principle verification device in step S100. Simultaneously, the intensities of the first and second sub-lasers in this step are also determined by the principle verification device in step S100.

[0075] As a specific example, lasers with wavelengths of 477nm and 532nm are selected. These two lasers are combined, and after the power stability of the lasers is detected by beam splitting, they are then used to form a sheet beam through a sheet beam assembly. Rhodamine B and sodium fluorescein are selected as the fluorescent staining agents. Rhodamine B has a fluorescence wavelength of 532nm, producing a fluorescence peak of approximately 550–560nm, and its fluorescence intensity is negatively correlated with temperature. Sodium fluorescein has a fluorescence wavelength of 477nm, with a fluorescence peak of approximately 500–520nm, and its fluorescence intensity is positively correlated with temperature.

[0076] S300: Two types of fluorescence pass through the imaging lens. The light rays exiting the imaging lens are dispersed into a first ray and a second ray after passing through a beam splitting and filtering module. The first ray passes through a first reflection adjustment module and then to an image combining module, while the second ray passes through a second reflection adjustment module and then to an image combining module. A camera images the first ray and the second ray through the image combining module separately to obtain the fluorescence signal.

[0077] In this step, two types of fluorescence pass through an imaging lens to image the object (i.e., the working medium containing the fluorescent agent). The light rays exiting the imaging lens are dispersed into a first ray (i.e., light rays above a specific spectral threshold) and a second ray (light rays below a specific spectral threshold) after passing through a spectral filtering module. The first ray and the second ray are imaged separately. The first ray is reflected by a first reflection adjustment module to an image combining module, and the second ray is reflected by a second reflection adjustment module to an image combining module. A camera then images the first ray and the second ray after passing through the image combining module to obtain the fluorescence signal.

[0078] S400: Change the temperature of the first working fluid to be tested, and measure the fluorescence signal of the first working fluid to be tested at different specific temperatures according to the method in step S300, so as to obtain the fluorescence signal-temperature relationship curve of the first working fluid to be tested.

[0079] In this step, the temperature of the first working medium to be tested is changed according to the set temperature (e.g., 0℃, 10℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, etc.), and then the fluorescence signal of the first working medium to be tested at each set temperature is measured according to the method of step S300, so as to obtain the fluorescence signal-temperature relationship curve of the first working medium to be tested.

[0080] S500: Based on the fluorescence signal-temperature relationship curve, it infers the temperature distribution at the measurement location from the fluorescence signal obtained by the camera.

[0081] In this step, since only the fluorescence intensity corresponding to the set temperature (e.g., 0℃, 10℃) was measured in step S400, and the temperature between 0℃ and 10℃ was not measured, the fluorescence signal corresponding to this temperature range can be determined using a linear scale method. Therefore, based on the fluorescence signal-temperature relationship curve, the temperature distribution corresponding to the measurement location can be inferred from the fluorescence signal obtained by the camera.

[0082] According to the above embodiments of the present invention, the method for measuring the temperature field of a fluid employs a single-camera dual-color PLIF measurement device that integrates the optical measurement components into a single unit. This reduces the difficulty and complexity of optical adjustment, making the adjustment and use of the optical measurement components more convenient. The method uses a spectral splitting and imaging adjustment module formed by combining a spectral filtering module, a first reflection adjustment module, a second reflection adjustment module, and an image combining module. Only one set of camera and imaging lens is needed to generate dual images of different spectral bands required for dual-color PLIF. After adjustment, the deviation between the dual images presented by the camera is minimal, eliminating the need for a dedicated algorithm to correct and match the dual images. The dual-color laser-induced fluorescence measurement device used in this method has a high degree of integration and can use a wider range of optical magnifications compared to products currently offered by commercial measurement manufacturers.

[0083] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0084] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A single-camera dual-color PLIF measuring device, characterized in that, include: A first laser is used to excite two fluorescent agents contained in a first test medium to generate two types of fluorescence. An imaging lens, wherein two types of fluorescence excited by the first laser enter the imaging lens for imaging; The beam splitting and image splitting adjustment module includes a beam splitting filter module, a first reflection adjustment module, a second reflection adjustment module, and an image combining module. Light rays exiting the imaging lens are split into a first ray and a second ray after passing through the beam splitting filter module, and the wavelength of the first ray is greater than the wavelength of the second ray. The first ray passes through the first reflection adjustment module and then to the image combining module, and the second ray passes through the second reflection adjustment module and then to the image combining module. A camera, used to image the first light ray and the second light ray passing through the image combining module, respectively.

2. The single-camera dual-color PLIF measuring device according to claim 1, characterized in that, The first laser includes a first sub-laser and a second sub-laser; The device further includes: a first laser beam combiner module, which is used to combine the laser emitted by the first sub-laser and the laser emitted by the second sub-laser. The device further includes: a first beam splitter module and a first laser energy meter, wherein the first beam splitter module is disposed in the optical path between the first laser beam combiner module and the first working medium to be tested, and the first laser energy meter is disposed on the laser path split by the first beam splitter module; The device further includes a first optical component, which is disposed in the optical path between the first beam splitting module and the first working medium to be tested.

3. The single-camera dual-color PLIF measuring device according to claim 1, characterized in that, Also includes: An aperture controller is disposed at the end of the imaging lens near the first working medium to be tested; And / or, further comprising: an adjustable slit disposed at one end of the imaging lens near the beam splitting and image adjustment module.

4. The single-camera dual-color PLIF measuring device according to claim 3, characterized in that, Also includes: A first adapter is connected between the adjustable slit and the beam splitting and imaging adjustment module; And / or, further comprising: a second adapter connected between the beam splitting and image adjustment module and the camera.

5. The single-camera dual-color PLIF measuring device according to any one of claims 1-4, characterized in that, The spectral filtering module is equipped with a long-wavelength pass and short-wavelength reflector. And / or, the first reflection adjustment module is provided with a first reflector; And / or, the second reflection adjustment module is provided with a second reflector; And / or, the image combining module is equipped with a long-wavelength anti-short-wavelength dichroic mirror; And / or, the camera is provided with a light-sensitive component.

6. The single-camera dual-color PLIF measuring device according to claim 5, characterized in that, The beam splitting and imaging adjustment module further includes a long-pass filter and a first narrow-band trap, wherein the long-pass filter and the first narrow-band trap are respectively disposed between the long-pass short-wave reflection beam splitter and the first reflector. And / or, the beam splitting and imaging adjustment module further includes a bandpass filter and a second narrowband trap, wherein the bandpass filter and the second narrowband trap are respectively disposed between the long-wavelength short-wavelength reflection beam splitter and the second reflector.

7. The single-camera dual-color PLIF measuring device according to any one of claims 1-4, characterized in that, The first test medium includes a first fluorescent agent and a second fluorescent agent. The fluorescence intensity of the first fluorescent agent is positively correlated with temperature, and the fluorescence intensity of the second fluorescent agent is negatively correlated with temperature. Alternatively, the fluorescence intensity of the first fluorescent agent is positively correlated with temperature, while the fluorescence intensity of the second fluorescent agent is uncorrelated with temperature; Alternatively, the fluorescence intensity of the first fluorescent agent is negatively correlated with temperature, while the fluorescence intensity of the second fluorescent agent is zero-correlated with temperature.

8. The single-camera dual-color PLIF measuring device according to any one of claims 1-4, characterized in that, It also includes: a principle verification device, which is used to determine the light intensity of the first laser, the types and concentrations of the two phosphors in the first working fluid to be tested, and the principle verification device includes: a second laser, a second laser beam combiner module, a second beam splitter module, a second laser energy meter, a second optical component, a second working fluid to be tested, a fluorescence receiving module, and a spectrometer. The second laser includes a third sub-laser and a fourth sub-laser. The second laser beam combiner module is used to combine the laser emitted by the third sub-laser and the laser emitted by the fourth sub-laser. The second beam splitter module, the second optical component, and the second working fluid to be tested are sequentially arranged in the optical path of the combined laser beam. The second laser energy meter is arranged on the laser path split by the second beam splitter module. The second working fluid to be tested generates two types of fluorescence under the excitation of the laser emitted by the second optical component. The fluorescence receiving module includes a focusing lens and a third narrowband trap. The fluorescence generated by the second working fluid to be tested passes sequentially through the focusing lens and the third narrowband trap. The fluorescence receiving module and the spectrometer are connected by an optical fiber.

9. A method for measuring the temperature field of a fluid using the single-camera dual-color PLIF measuring device according to any one of claims 1-8, characterized in that, include: (1) Determine the light intensity of the first laser, the types and concentrations of the two fluorescent agents in the first working medium to be tested; (2) Activate the first laser to excite the first working fluid to produce two types of fluorescence; (3) The two types of fluorescence pass through the imaging lens. The light rays coming out of the imaging lens are dispersed into a first light ray and a second light ray after passing through the beam splitting and filtering module. The first light ray passes through the first reflection adjustment module and then to the image combining module. The second light ray passes through the second reflection adjustment module and then to the image combining module. The camera is used to image the first light ray and the second light ray that have passed through the image combining module respectively, so as to obtain the fluorescence signal. (4) Change the temperature of the first working fluid to be tested, and measure the fluorescence signal of the first working fluid to be tested at different specific temperatures according to the method in step (3) so as to obtain the fluorescence signal-temperature relationship curve of the first working fluid to be tested; (5) Based on the fluorescence signal-temperature relationship curve, the temperature distribution at the measurement location is inferred from the fluorescence signal obtained by the camera.

10. The method according to claim 9, characterized in that, Step (1) includes the following steps: The second laser is activated to excite the second analyte containing any two fluorescent agents to produce two types of fluorescence; The two fluorescent agents are sequentially passed through a focusing lens and a third narrow-band trap before entering a spectrometer. Based on the change in fluorescence intensity over time, the fluorescence intensity-laser irradiation relationship curves of the two fluorescent agents are obtained, so as to select the appropriate light intensity of the second laser, the type of fluorescent agent, and the concentration.

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