A high-frequency hydroxyl labeling speed measurement device and method

Abstract

The present invention discloses a high-frequency hydroxyl labeling speed measurement device and method, which relate to the field of non-contact flow field measurement technology. The device and method comprise: an ultraviolet femtosecond laser, two shaping units, a first laser, a camera, a timing controller and a computer; the ultraviolet femtosecond laser is used to output an ultraviolet femtosecond laser, which is shaped into a filamentary laser by the first shaping unit and then injected into a flow field measurement area to generate labeled molecules; the first laser is used to output a first laser which is shaped into a sheet laser by the second shaping unit and then injected into the flow field measurement area to generate labeled molecule fluorescence; the camera is used to collect labeled molecule fluorescence images to obtain spatiotemporal data; the timing controller controls the timing of various components of the device; and the computer processes the spatiotemporal data of the labeled molecule fluorescence to obtain the flow field velocity; the present invention selects an ultraviolet femtosecond laser with high instantaneous energy density as a writing laser to improve the repetition frequency of various components, thereby solving the problem that conventional hydroxyl labeling speed measurement depends on the high temperature conditions of the flow field environment to be measured and the repetition frequency is low.

Description

Technical Field

[0001] The present invention relates to the technical field of non-contact flow field measurement, and in particular to a high-frequency hydroxyl labeling speed measurement device and method. Background Art

[0002] Flow field velocity measurement technology plays a key role in fields such as flow mechanism research and aeroengine development. Currently, common flow field velocity measurement technologies fall into two categories: one is invasive velocity measurement technology, such as hot wire anemometers and pitot tubes. These traditional methods are relatively simple, highly commercialized, and inexpensive, but they also have significant disadvantages. Invasive velocity measurement methods introduce shock wave interference, altering the original flow field state. The other is non-invasive velocity measurement technology based on laser diagnostic technology, also known as non-contact velocity measurement technology, such as image tracer velocity measurement and molecular labeling velocity measurement. These measurement systems do not require intrusion into the flow field and are currently the mainstream flow field velocity measurement technology.

[0003] Molecular labeling velocimetry is a technique that uses specific molecules in a flow field as marker molecules and measures velocity by acquiring the displacement of the marker molecules over a certain period of time. The molecular labeling velocimetry process generally includes two key steps: the first step is the writing process, the main purpose of which is to produce marker molecules. The marker molecules can be generated by spreading the marker molecules into the flow field, or by utilizing inherent marker molecules present in the flow field, or by utilizing inherent substances present in the flow field. The second step is the reading process, the main purpose of which is to use imaging methods to track the spatial position of the marker molecules. Most molecular labeling velocimetry technologies use planar laser-induced fluorescence imaging technology as the imaging method in this process. Hydroxyl labeling velocimetry technology falls under the category of molecular labeling velocimetry technology, and its marker molecule is hydroxyl.

[0004] Excimer lasers have the characteristics of high single pulse energy and short wavelength. Therefore, the conventional hydroxyl labeling velocimetry writing process usually uses a 193nm excimer laser with a nanosecond pulse width to photodissociate water molecules in the flow field to produce labeled molecular hydroxyl groups, as shown in references 1-5:

[0005] Reference 1: Lahr MD, Pitz RW, Douglas ZW, et al. Hydroxyl-Tagging-Velocimetry Measurements of a Supersonic Flow over a Cavity[J]. JOURNAL OFPROPULSION AND POWER, 2010, 26(4): 790-797.

[0006] Reference 2: Ribarov L, Hu S, Wehrmeyer J, et al. Hydroxyl tagging velocimetry method optimization: signal intensity and spectroscopy[J]. APPLIED OPTICS, 2005, 44(31): 6616-6626.

[0007] Reference 3: Pitz R, Lahr M, Douglas Z, et al. Hydroxyl tagging velocimetry in a supersonic flow over a cavity[J]. APPLIED OPTICS, 2005, 44(31): 6692-6700.

[0008] Reference 4: Ribarov L, Wehrmeyer J, Pitz R, et al. Hydroxyl tagging velocimetry (HTV) in experimental air flows[J]. APPLIED PHYSICS B-LASERS AND OPTICS, 2002, 74(2): 175-183.

[0009] Reference 5: Li G, Ye J, Zhang Z, et al. Velocimetry and thermometry in intermediate temperature flow using planar laser-induced fluorescence of OH from photo-dissociation of H2O[J]. EXPERIMENTS IN FLUIDS, 2020, 61(8).

[0010] The 193nm laser photodissociation of water molecules in a vibrationally excited state involves a single-photon absorption process. Since the absorption cross-section of water molecules for 193nm photons is small at room temperature, high temperature conditions help to increase the absorption cross-section. Therefore, conventional hydroxyl labeling velocimetry technology is more suitable for high-temperature combustion flow fields. In addition, due to limitations such as the writing laser and camera repetition frequency, the repetition frequency of conventional hydroxyl labeling velocimetry systems usually does not exceed 10Hz. When the normal operation time of the wind tunnel flow field is short, it is difficult for conventional hydroxyl labeling velocimetry systems to obtain valid data in a single-vehicle wind tunnel test. In summary, conventional hydroxyl labeling velocimetry technology has the problem of relying on the high temperature conditions of the flow field environment to be measured and the low repetition frequency. Summary of the Invention

[0011] The purpose of the present invention is to solve the problem that conventional hydroxyl labeling velocimetry technology relies on high temperature conditions and low repetition frequency of the flow field environment to be measured by selecting an ultraviolet femtosecond laser with high instantaneous energy density as the writing laser and improving the repetition frequency of each component, thereby expanding the applicable occasions of hydroxyl labeling velocimetry technology.

[0012] To achieve the above-mentioned object of the invention, the present invention provides a high-frequency hydroxyl labeling speed measuring device, the device comprising:

[0013] Ultraviolet femtosecond laser, a first shaping unit, a first laser, a second shaping unit, a camera, a timing controller and a computer;

[0014] Among them, the ultraviolet femtosecond laser is used to output ultraviolet femtosecond laser, which is shaped into a filamentary laser by the first shaping unit and then injected into the flow field measurement area to generate labeled molecules; the first laser is used to output a first laser, which is shaped into a sheet laser by the second shaping unit and then injected into the flow field measurement area to generate labeled molecule fluorescence; the camera is used to collect labeled molecule fluorescence images and obtain the spatiotemporal data of the labeled molecule fluorescence; the timing controller is connected to the flow field trigger signal and is connected to the ultraviolet femtosecond laser, the first laser and the camera, and is used to control the timing of the ultraviolet femtosecond laser, the first laser and the camera; the computer is used to process the spatiotemporal data of the labeled molecule fluorescence to obtain the one-dimensional flow field velocity of the filamentary laser position in the flow field measurement area.

[0015] The underlying principle of the present invention is as follows: As can be seen from References 1-5 in the background literature, conventional hydroxyl labeling velocimetry techniques inherently utilize a relatively high single-pulse energy 193nm excimer laser to photodissociate water via a single-photon absorption process, with a laser pulse width in the nanosecond range. In practice, the photodissociation process requires a relatively high instantaneous energy density. Beyond the single-photon absorption process, the use of a femtosecond laser with a pulse width in the femtosecond range to photodissociate water via a two- or multi-photon absorption process is also a novel approach. Although the single-pulse energy of a femtosecond laser is lower than that of an excimer laser, its instantaneous energy density far exceeds that of an excimer laser. Furthermore, the high instantaneous energy density of a femtosecond laser offsets the effect of water molecules' low absorption cross-section at room temperature for long wavelengths. When the ultraviolet wavelength of a femtosecond laser is relatively short (e.g., 182nm), the method of photodissociating water via a single-photon absorption process using a femtosecond laser with a pulse width in the femtosecond range offers advantages over the excimer method, manifested in higher single-photon energy and higher instantaneous energy density. After generating the labeled molecules using the above method, the spatial position of the labeled molecules is recorded using high-frequency hydroxyl-planar laser-induced fluorescence imaging technology, and the one-dimensional velocity of the flow field at the position of the filamentous writing laser in the sheet reading laser plane can be calculated.

[0016] Preferably, the device further comprises: a filter, which is installed in front of the lens of the camera, and is used to transmit the fluorescence of the labeled molecules and filter out stray light such as laser scattered light, thereby improving the signal-to-noise ratio of the fluorescence image.

[0017] Preferably, the device further comprises a plurality of reflectors, which are installed on the optical path of the ultraviolet femtosecond laser and the first laser transmitted to the flow field measurement area. The reflectors can be used to adjust the optical path.

[0018] Preferably, the filamentary laser is used to photodissociate water molecules in the flow field measurement area to generate labeled molecular hydroxyl groups; and the sheet laser is used to generate labeled molecular hydroxyl fluorescence.

[0019] Preferably, the repetition frequency of the ultraviolet femtosecond laser, the first laser, and the camera are all tunable within a range of 1kHz-10kHz, and the repetition frequency of the high-frequency hydroxyl labeling velocimetry device is also 1kHz-10kHz. This design ensures consistent repetition frequencies across all components of the device, preventing a single component from operating at a low repetition rate from causing the entire device to fall behind. The repetition frequency of the entire device is determined by the component with the lowest repetition frequency. Conventional hydroxyl labeling velocimetry devices are limited by factors such as the repetition rates of the writing laser and the camera, typically resulting in a repetition frequency of no more than 10Hz. The reasons for this are: first, conventional hydroxyl labeling velocimetry devices use a 193nm excimer laser as the writing laser, which has a low repetition rate (approximately 10Hz). Second, precisely because of the first factor contributing to the low repetition frequency of the entire device, the cameras used in most published work do not necessarily require high repetition rate cameras. This device breaks through the inherent design principles of hydroxyl labeling velocimetry by using a high-repetition-rate femtosecond laser as the writing laser, eliminating the repetition frequency limitations of the components within the device. Therefore, compared with the conventional hydroxyl labeling speed measurement device, the repetition frequency of the device is improved.

[0020] Preferably, the output laser wavelength of the ultraviolet femtosecond laser is 182 nm-266 nm, and the output laser wavelength of the first laser is 282 nm.

[0021] Preferably, the ultraviolet femtosecond laser includes a femtosecond laser and a nonlinear frequency conversion device.

[0022] Preferably, the camera is positioned normal to the laser sheet, and is used to image the calibration plate to obtain the camera's imaging magnification, as well as to image the labeled molecule fluorescence and record its location. The labeled molecule fluorescence and the calibration plate are both located in the plane of the laser sheet, allowing the camera to capture both the labeled molecule fluorescence and the calibration plate in a forward direction.

[0023] Preferably, the camera comprises a body and a lens that respond only to ultraviolet wavelengths.

[0024] Preferably, the filamentary laser light and the sheet-shaped laser light are transmitted in opposite directions, and the focal planes of the filamentary laser light, the sheet-shaped laser light and the camera are coplanar.

[0025] To achieve the above-mentioned object of the invention, the present invention further provides a high-frequency hydroxyl labeling speed measurement method, which is based on the high-frequency hydroxyl labeling speed measurement device described above, and comprises:

[0026] Step 1: Determine the flow field measurement area and set a calibration plate in the flow field measurement area to determine the camera imaging magnification;

[0027] Step 2: Turn on the flow field, the ultraviolet femtosecond laser, the first laser, the timing controller, and the camera; the ultraviolet femtosecond laser output is shaped into a filamentary laser by the first shaping unit and then injected into the flow field measurement area to generate labeled molecules; the first laser output is shaped into a sheet laser by the second shaping unit and then injected into the flow field measurement area to generate labeled molecule fluorescence;

[0028] Step 3: Use a camera to capture the fluorescence image of the labeled molecule and obtain the spatiotemporal data of the fluorescence of the labeled molecule;

[0029] Step 4: Based on the spatiotemporal data of the labeled molecule fluorescence, calculate the one-dimensional flow field velocity at the position of the filamentary laser in the flow field measurement area.

[0030] One or more technical solutions provided by the present invention have at least the following technical effects or advantages:

[0031] By using laser photodissociation to generate labeled molecules from substances in the flow field, the shortcomings of invasive velocity measurement methods, such as introducing shock wave interference and changing the original state of the flow field to be measured, are avoided, and the velocity measurement results are more accurate and reliable.

[0032] Using an ultraviolet femtosecond laser as the writing laser for the hydroxyl labeling velocimetry device provides a new method for generating labeled molecular hydroxyl groups. While conventional hydroxyl labeling velocimetry devices, which use 193nm excimer writing lasers only for high-temperature conditions, this method can be applied at both room and high temperatures, expanding the applicable flow field temperature range.

[0033] Due to the breakthrough of the inherent hydroxyl labeling speed measurement concept, the writing laser has become a high-repetition-rate femtosecond laser, and other components can also use high-repetition-rate commercial products. The repetition frequency of each component in the entire device has no shortcomings, so the repetition frequency of the entire device is increased to 1kHz-10kHz. In the flow field with a shorter continuous operation time, multiple sets of valid data can still be obtained, which expands the applicable range of the flow field operation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of the present invention, and do not constitute a limitation of the embodiments of the present invention;

[0035] Figure 1 This is a schematic diagram of the composition of a high-frequency hydroxyl labeling speed measurement device;

[0036] Figure 2 Schematic diagram of a high-frequency hydroxyl labeling speed measurement method;

[0037] Among them, 1-ultraviolet femtosecond laser, 2-flow field trigger signal, 3-timing controller, 4-first laser, 5-first reflector, 6-first shaping unit, 7-flow field measurement area, 8-second shaping unit, 9-second reflector, 10-filter, 11-camera, 12-computer. DETAILED DESCRIPTION

[0038] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features therein can be combined with each other without conflict.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0040] Embodiment 1;

[0041] Please refer to Figure 1 , Figure 1 The figure is a schematic diagram of the components of a high-frequency hydroxyl labeling speed measurement device. Embodiment 1 of the present invention provides a high-frequency hydroxyl labeling speed measurement device. The speed measurement device includes an ultraviolet femtosecond laser 1, a timing controller 3, a first laser 4, a first shaping unit 6, a second shaping unit 8, a filter 10, a camera 11, and a computer 12.

[0042] The ultraviolet femtosecond laser 1 outputs ultraviolet femtosecond laser light, also known as a writing laser, which is used to photodissociate water molecules in the flow field to produce labeled molecular hydroxyl groups. The ultraviolet femtosecond laser 1 has an output laser wavelength between 182nm and 266nm and is composed of an 800nm ​​femtosecond laser and a nonlinear frequency conversion device. The nonlinear frequency conversion device can be a frequency tripler for generating 266nm ultraviolet femtosecond laser light, or an optical parametric oscillator for generating 182nm to 265nm ultraviolet femtosecond laser light.

[0043] The first laser 4 is a 282nm laser that outputs a 282nm wavelength laser, also known as the read laser. This read laser is used to generate fluorescence from the labeled molecules. The first laser 4 is composed of a 532nm Nd:YAG laser, a dye laser, and a frequency doubler. The read laser is generated as follows: the 532nm Nd:YAG laser pumps the dye to produce a 563nm wavelength laser, which is then frequency doubled to produce a 282nm wavelength read laser.

[0044] The first shaping unit 6 is used to shape the writing laser into a filamentary laser beam, so that the labeled molecules are generated only along the line of the filamentary laser beam. The second shaping unit 8 is used to shape the reading laser beam into a sheet-like laser beam, which is used to display the fluorescence of the labeled molecules. The sheet-like laser beam forms a surface, and the reading laser beam and the writing laser beam are coplanar. The fluorescence of the labeled molecules is initially located on the filamentary laser beam. After a period of time, the fluorescence of the labeled molecules moves to other positions on this surface with the flow field. This configuration facilitates the camera to capture the fluorescence of the labeled molecules at two moments in time.

[0045] On the optical path of the writing laser and the reading laser transmitted to the flow field measurement area, a number of the aforementioned reflectors can be added according to the need to adjust the direction of the optical path. Figure 1 Only the first reflector 5 and the second reflector 9 are shown. In practical applications, the number and position of the reflectors can be adjusted as needed, and the embodiment of the present invention does not limit the same.

[0046] The camera 11 is placed in the normal direction of the sheet laser and is used to image the calibration plate to obtain the camera imaging magnification, and to image the fluorescence of the labeled molecules and record the location of the labeled molecule fluorescence; the filter 10 is a narrow-band filter near the wavelength of 308nm, which is used to transmit the fluorescence of the labeled molecules and filter out stray light such as laser scattered light, thereby improving the signal-to-noise ratio of the fluorescence image;

[0047] The timing controller 3 is connected to the flow field trigger signal 2, the ultraviolet femtosecond laser 1, the first laser 4 and the camera 11, and is used to control the timing of the four; the computer 12 is used to control the operation of the ultraviolet femtosecond laser 1, the first laser 4 and the camera 11 through software, and to store measurement data.

[0048] Embodiment 2;

[0049] Please refer to Figure 2 , Figure 2 Schematic diagram of a high-frequency hydroxyl labeling speed measurement method. Based on the speed measurement device described in Example 1, Example 2 of the present invention provides a high-frequency hydroxyl labeling speed measurement method, which specifically includes the following steps:

[0050] Step 1: Determine the flow field measurement area and set a calibration plate in the flow field measurement area to determine the camera imaging magnification;

[0051] Step 2: Turn on the flow field, the ultraviolet femtosecond laser, the first laser, the timing controller, and the camera; the ultraviolet femtosecond laser output is shaped into a filamentary laser by the first shaping unit and then injected into the flow field measurement area to generate labeled molecules; the first laser output is shaped into a sheet laser by the second shaping unit and then injected into the flow field measurement area to generate labeled molecule fluorescence;

[0052] Step 3: Use a camera to capture the fluorescence image of the labeled molecule and obtain the spatiotemporal data of the fluorescence of the labeled molecule;

[0053] Step 4: Based on the spatiotemporal data of the labeled molecule fluorescence, calculate the one-dimensional flow field velocity at the position of the filamentary laser in the flow field measurement area.

[0054] In step 1, a calibration plate is placed in the flow field measurement area 7, coplanar with the camera focal plane, and an image of the calibration plate of known length is captured by the camera 11 to obtain the camera imaging magnification.

[0055] In step 2, the writing laser is generated by the ultraviolet femtosecond laser 1 and focused into a filamentary laser beam by a first shaping unit 6 composed of lenses, which is incident on the flow field measurement area 7. The reading laser is generated by the first laser 4 and is shaped by a second shaping unit 8 composed of a concave lens and a cylindrical convex lens, resulting in a sheet-like laser beam that is incident on the flow field measurement area 7. The writing laser and the reading laser beam are transmitted in opposite directions to facilitate equipment layout. The focal planes of the filamentary writing laser beam, the sheet-like reading laser beam, and the camera 11 are coplanar. The reading laser beam is used to display the fluorescence of the labeled molecules, and the sheet-like laser beam forms a single surface. The reading laser beam is coplanar with the writing laser beam. Initially, the fluorescence of the labeled molecules is located on the filamentary laser beam. After a period of time, the fluorescence of the labeled molecules moves to other positions on this surface along with the flow field. This arrangement facilitates the camera to capture the fluorescence of the labeled molecules at both moments. The camera is positioned normal to the sheet-like laser beam, and its focal plane is also coplanar with the filamentary writing laser beam and the sheet-like reading laser beam, facilitating clear forward imaging of the fluorescence of the labeled molecules. On the optical path of the writing laser and the reading laser transmitted to the flow field measurement area 7, a number of the aforementioned reflectors can be added according to the need to adjust the direction of the optical path.

[0056] In step 2, after the flow field is turned on, the flow field trigger signal is at time t0, and the flow field establishes normal operation at time t1 (t1>t0). The flow field trigger signal 2 serves as the external trigger input signal of the timing controller 3. The flow field trigger signal 2 drives the timing controller 3 to work. At time t2 (t2≥t1), the ultraviolet femtosecond laser 1 is turned on. At time t3 (t3≥t2), the first laser 4 and the camera 11 are turned on at the same time. The labeled molecule fluorescence flight time t refers to the start timing difference between the writing laser and the reading laser, that is, t=t3-t2. The timing controller sets t=t a , use the camera to collect the fluorescent image of the labeled molecule to obtain the first spatiotemporal data set of the fluorescent labeled molecule; then, the timing controller sets t=t b , obtain the second spatiotemporal dataset of labeled molecule fluorescence.

[0057] In step 3, the spatiotemporal data of the marker molecule fluorescence refers to the spatial distribution data of the marker molecule fluorescence at the moment of camera shooting.

[0058] In step 4, the fluorescence of the labeled molecule at t can be obtained from the first spatiotemporal dataset and the second spatiotemporal dataset. b -t a The displacement s of the fluorescence generated during the time is used to calculate the flow field velocity v=s / (t b -t a ).

[0059] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0060] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A high-frequency hydroxyl labeling speed measuring device, characterized in that: The device comprises: Ultraviolet femtosecond laser, a first shaping unit, a first laser, a second shaping unit, a camera, a timing controller and a computer; Wherein, the ultraviolet femtosecond laser is used to output ultraviolet femtosecond laser, which is shaped into a filamentary laser by the first shaping unit and then injected into the flow field measurement area to generate labeled molecules; the first laser is used to output a first laser, which is shaped into a sheet laser by the second shaping unit and then injected into the flow field measurement area to generate labeled molecule fluorescence; the camera is used to collect labeled molecule fluorescence images and obtain spatiotemporal data of the labeled molecule fluorescence; the timing controller is connected to the flow field trigger signal and is connected to the ultraviolet femtosecond laser, the first laser and the camera, and is used to control the timing of the ultraviolet femtosecond laser, the first laser and the camera; the computer is used to process the spatiotemporal data of the labeled molecule fluorescence to obtain the one-dimensional flow field velocity of the filamentary laser position in the flow field measurement area; An ultraviolet femtosecond laser is used as a writing laser, and the ultraviolet femtosecond laser includes an 800nm ​​femtosecond laser and a nonlinear frequency conversion device; the output laser wavelength of the ultraviolet femtosecond laser is 182nm-266nm, and the output laser wavelength of the first laser is 282nm; the repetition frequency tunable range of the ultraviolet femtosecond laser, the first laser and the camera is 1kHz-10kHz, and the repetition frequency of the high-frequency hydroxyl labeling speed measuring device is 1kHz-10kHz.

2. A high-frequency hydroxyl labeling speed measuring device according to claim 1, characterized in that: The device further comprises: a filter, which is installed in front of the lens of the camera.

3. A high-frequency hydroxyl labeling speed measuring device according to claim 1, characterized in that: The device further includes a plurality of reflectors, which are installed on the optical path of the ultraviolet femtosecond laser and the first laser transmitted to the flow field measurement area.

4. A high-frequency hydroxyl labeling speed measuring device according to claim 1, characterized in that: The filamentary laser is used for photodissociation of water molecules in the flow field measurement area to generate labeled molecular hydroxyl groups; and the sheet laser is used for generating labeled molecular hydroxyl fluorescence.

5. A high-frequency hydroxyl labeling speed measuring device according to claim 1, characterized in that: The camera includes a body and a lens that respond only to ultraviolet wavelengths.

6. A high-frequency hydroxyl labeling speed measuring device according to claim 1, characterized in that: The camera is arranged in the normal direction of the sheet laser, and is used to image the calibration plate to obtain the camera imaging magnification, and to image the fluorescence of the labeled molecules and record the position of the fluorescence of the labeled molecules.

7. A high-frequency hydroxyl labeling speed measuring device according to claim 1, characterized in that: The filament laser and the sheet laser are transmitted in opposite directions, and the focal planes of the filament laser, the sheet laser and the camera are coplanar.

8. A high-frequency hydroxyl labeling speed measurement method, the method being based on a high-frequency hydroxyl labeling speed measurement device according to any one of claims 1 to 7, characterized in that: The method comprises: Step 1: Determine the flow field measurement area and set a calibration plate in the flow field measurement area to determine the camera imaging magnification; Step 2: Turn on the flow field, the ultraviolet femtosecond laser, the first laser, the timing controller, and the camera; the ultraviolet femtosecond laser output is shaped into a filamentary laser by the first shaping unit and then injected into the flow field measurement area to generate labeled molecules; the first laser output is shaped into a sheet laser by the second shaping unit and then injected into the flow field measurement area to generate labeled molecule fluorescence; Step 3: Use a camera to capture the fluorescence image of the labeled molecule and obtain the spatiotemporal data of the fluorescence of the labeled molecule; Step 4: Based on the spatiotemporal data of the labeled molecule fluorescence, calculate the one-dimensional flow field velocity at the position of the filamentary laser in the flow field measurement area.

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