Synchronous temperature and pressure measuring device based on femtosecond laser-induced grating spectrum technology

Abstract

The invention relates to the technical field of laser spectrum measurement, in particular to a synchronous temperature and pressure measurement device based on a femtosecond laser-induced grating spectrum technology, which uses two beams of femtosecond laser pulses with the same pulse energy and polarization state to interfere with each other in a medium. The thermal grating is induced through rapid energy deposition, sound waves are generated on the cross section of the thermal grating, then a beam of continuous laser enters the thermal grating at a first-order Bragg diffraction angle, photon-phonon interaction is generated between the continuous laser and the sound waves, and therefore a beam of coherent scattered light is generated at a four-wave mixing phase matching angle; the femtosecond laser induces the grating to scatter the signal light. The signal light has a periodic oscillation structure in time, the signal intensity presents an exponential decay rule along with time, and the oscillation period and the decay time constant are respectively related to the sound wave propagation speed and the thermal diffusion rate, so that the dependency relationship between the measurement result and the gas state can be established; therefore, temperature and pressure information can be calculated by measuring femtosecond laser induced grating scattering signals.

Description

Technical Field

[0001] This invention relates to the field of laser spectroscopy measurement technology, specifically to a synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology. Background Technology

[0002] In modern combustion diagnostics and fluid mechanics research, the accurate measurement of temperature and pressure parameters under high-temperature, high-pressure, and high-turbulence environments (especially in the development of cutting-edge defense equipment such as military aero-engines and scramjet engines) has significant scientific research and engineering application value. Traditional contact sensors, such as thermocouples and pressure probes, are limited by millisecond-level response speeds, interference with the flow field, and temperature limits (typically <1800K), making it difficult to meet the extreme operating condition measurement requirements of modern combustion systems, such as scramjet engines and gas turbine combustors. Despite significant progress in non-contact optical diagnostic technologies, such as laser-induced fluorescence (LIF), coherent anti-Stokes Raman scattering (CARS), and Rayleigh / Raman scattering, their engineering applications still face the following bottlenecks: LIF technology relies on tracers (such as OH radicals) and is significantly affected by quenching effects, with signal intensity exhibiting exponential decay under high pressure; while CARS technology boasts high accuracy, it requires complex optical path configurations and narrowband lasers, and temperature inversion depends on compositional information, making it susceptible to Doppler broadening under high pressure, leading to a rapid decrease in temperature inversion accuracy; Rayleigh / Raman scattering technology is limited by low signal intensity and particle scattering interference, restricting its practicality in turbulent combustion fields. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology, which is suitable for thermodynamic parameter diagnosis in extreme environments (such as high-temperature, high-pressure, high-turbulence combustion fields, low-temperature plasma, and hypersonic flow fields).

[0004] To achieve the above objectives, the following technical solution is provided:

[0005] A synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology is characterized by comprising a laser source, a pump light polarization and energy control component, a first beam splitter 5, a second beam splitter 6, a polarization control component, a high-reflectivity mirror 8, a high-precision delay control component 9, an optical coupling component, an environmental control device 14, an optical path calibration and filtering component, a signal collection system, a sampling mirror 22, and a CMOS camera 23.

[0006] The laser source is used to generate femtosecond pump light 1 and continuous probe light 2; the pump light polarization and energy control component is used to adjust the polarization state of the pump light and to adjust the total pump light energy; the first beam splitter 5 is used to split the pump light into two pump lights with equal energy; the polarization control component adjusts the half-wave plate 7 to make the two pump lights have the same polarization state after passing through the analyzer; the high-precision delay control component 9 includes a precision electric displacement slide and two high-reflection mirrors to control the two pump pulses to achieve time coincidence on the femtosecond scale; the optical coupling component includes a first dichroic mirror 12 and a first cross lens 13, the first dichroic mirror 12 is used to combine the pump light and probe light, and the first cross lens 13 is used to focus the two pump lights at a small angle to cause interference and form a thermal grating, while focusing the probe light; the environmental control device 14 is used to control the temperature and pressure at the position of the thermal grating; the second beam splitter 6 is used to... The laser light output from the continuous laser source is split into two beams at a ratio of 9:1, serving as a probe beam 10 and a tracking beam 11. The probe beam 10 is incident on the thermal grating at a Bragg first-order diffraction angle and scattered, thereby generating a coherent femtosecond laser-induced grating spectroscopy signal beam in the phase-matching direction. The tracking beam 11 is used to track the propagation direction of the signal beam and is turned off during measurement. The optical path calibration and filtering components are used to adjust the propagation direction of the four beams and effectively block and filter stray light. The signal collection system includes a monochromator 19, a photomultiplier tube 20, and an oscilloscope 21. The monochromator 19 is used to further filter stray light, the photodetector 20 is used to convert the signal beam into an electrical signal, and the oscilloscope 21 is used to record the time-domain evolution waveform of the femtosecond laser-induced grating spectroscopy signal. The CMOS camera 23 is used to acquire and process the grating fringe image to obtain the grating fringe spacing and further calculate temperature and pressure parameters.

[0007] Preferably, the laser source includes a Ti:sapphire femtosecond laser with a center wavelength of 800 nm and a continuous laser with a center wavelength of 532 nm. The two pump beams generated by the femtosecond laser interfere in the intersection region to form a laser-induced grating, and then form a thermal grating through energy deposition. The probe beam generated by the continuous laser is used to scatter with the thermal grating to generate a femtosecond laser-induced grating scattering signal.

[0008] Preferably, the pump light polarization and energy control component includes a half-wave plate 3 and a polarizing mirror 4. The half-wave plate 3 is used to change the polarization state of the pump light, and the polarizing mirror 4 is used to selectively transmit horizontally polarized pump light, thereby adjusting the total pump light energy by rotating the half-wave plate 3.

[0009] Preferably, the environmental control device 14 includes a tubular furnace, a ventilation pipeline, a water-cooling pipeline, and a pressure measuring device. The tubular furnace is temperature-regulated by an intelligent temperature controller, with a maximum operating temperature of 1200℃ and a rated power of 1200W. Quartz windows are installed at both ends of the tubular furnace for inflation and deflation operations. The tubular furnace can withstand a pressure of 5 atmospheres. The pressure gauge is connected to the sealed tubular furnace and is used to record the pressure inside the tube.

[0010] Preferably, the optical path calibration and filtering assembly includes a second cross lens 15, an optical trap 16, and a second dichroic mirror 17. The second cross lens 15 is identical in specifications to the first cross lens 13 and is symmetrically placed relative to the focal point. It is used to collimate four beams of light (two pump beams, a probe beam, and a signal beam) so that their propagation direction is horizontal. The optical trap 16 is used to block the pump beam and probe beam that pass through the second cross lens 15. The second dichroic mirror 17 is also used to reflect the signal beam and transmit the pump beam.

[0011] Preferably, the signal collection system first collimates the scattered signal through the cross lens 18, and after multiple reflections, it enters the monochromator 19 to further filter stray light. Subsequently, the signal enters the photomultiplier tube, where the optical signal is converted and amplified into an electrical signal. Finally, the time-domain evolution waveform of the scattered signal is collected by the oscilloscope.

[0012] Preferably, the CMOS camera 23 acquires and processes the grating stripe image to obtain the grating stripe spacing and further calculates the temperature and pressure parameters.

[0013] The beneficial effects of this invention are as follows:

[0014] This invention proposes a synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy. As an emerging nonlinear optical diagnostic method, it boasts significant advantages such as a simple experimental optical path, visually visible signals, high diagnostic accuracy, low pump laser energy threshold, high robustness, and simultaneous acquisition of multiple parameters. This technology uses two femtosecond laser pulses with identical pulse energy and polarization state to interfere with each other in a medium. Rapid energy deposition induces a thermal grating, generating acoustic waves in the grating's transverse cross-section. A continuous laser beam is then incident on the thermal grating at a first-order Bragg diffraction angle, causing photon-phonon interaction with the acoustic waves. This results in a coherent scattered light beam at the four-wave mixing phase-matching angle, i.e., the femtosecond laser-induced grating scattered signal light. The signal light exhibits a periodic oscillation structure in time, with its intensity decaying exponentially over time. The oscillation period and decay time constant are related to the acoustic wave propagation speed and thermal diffusion rate, respectively, thus establishing a dependency between the measurement results and the gas state. Therefore, temperature and pressure information can be calculated by measuring the femtosecond laser-induced grating scattered signal.

[0015] Compared to traditional nanosecond laser sources, femtosecond lasers (with a pulse width of approximately 10) -15 (s) The femtosecond laser possesses physical characteristics such as ultra-short pulse width, high peak power, and wide spectral bandwidth, which significantly improves energy deposition efficiency. While lowering the pump laser energy threshold (tens of microjoules), it greatly enhances signal intensity, making the signal visible to the naked eye. This not only simplifies signal acquisition but also significantly improves measurement accuracy. Furthermore, femtosecond lasers can excite multiple rotational spectral lines of molecules, making them more adaptable to gaseous media where the excitation and absorption wavelengths are not perfectly matched, reducing dependence on the pump laser resonant wavelength and greatly improving the robustness of the technology. Secondly, under high pressure, the signal intensity exhibits a power-law dependence on the pump light energy, and the number of signal oscillation periods increases rapidly with increasing pressure, further improving the accuracy of temperature and pressure measurements. Thirdly, the pump laser energy threshold is reduced by three orders of magnitude compared to nanosecond laser-induced grating scattering technology, not only avoiding interference from breakdown ionization but also enabling high-repetition-rate femtosecond laser-induced grating spectroscopy for diagnosing highly turbulent combustion flow fields.

[0016] Femtosecond laser-induced grating spectroscopy exhibits superior performance in complex and dynamic environments, particularly under extreme conditions such as rapid changes in local pressure or highly turbulent combustion, enabling high-precision, non-invasive, and spatially localized gas parameter measurements. This method holds broad application prospects in the diagnosis of thermodynamic parameters in high-pressure combustion systems such as gas turbines and internal combustion engines. It not only helps optimize combustion efficiency but also provides strong support for pollutant emission reduction and the development of clean energy technologies. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the optical path of the synchronous temperature and pressure measuring device in an embodiment of the present invention.

[0018] Figure 2 This is a physical diagram of a miniature open-type tube furnace according to an embodiment of the present invention.

[0019] Figure 3 This is a two-dimensional plasma grating stripe structure according to an embodiment of the present invention.

[0020] Figure 4 These are the time-domain evolution waveforms of femtosecond laser-induced grating scattering signals at different temperatures according to embodiments of the present invention.

[0021] Figure 5 The modulation frequency of the femtosecond laser-induced grating scattering signal at different temperatures is the embodiment of the present invention.

[0022] Figure 6 This is a comparison of temperature measurement results between femtosecond laser-induced grating spectroscopy and thermocouple readings in an embodiment of the present invention.

[0023] Figure 7 This invention relates to the accuracy and precision of the femtosecond laser-induced grating spectroscopy technology in temperature measurement relative to the actual temperature.

[0024] Figure 8 It is the attenuation constant of the stationary part in the laser-induced grating under different temperatures in the embodiments of the present invention, which is affected by thermal diffusion.

[0025] Figure 9 This is a comparison of pressure measurement results between the femtosecond laser-induced grating spectroscopy technology used in this invention and the readings of a high-precision absolute pressure barometer.

[0026] Figure 10 This invention relates to the precision and accuracy of the femtosecond laser-induced grating spectroscopy technology in pressure measurement relative to actual pressure. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] like Figure 1 As shown, this embodiment provides a synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology, which mainly includes a laser source, a pump light polarization and energy control component, a first beam splitter 5, a second beam splitter 6, a polarization control component, a high-reflectivity mirror 8, a high-precision delay control component 9, an optical coupling component, an environmental control device 14, an optical path calibration and filtering component, a signal collection system, a sampling mirror 22, and a CMOS camera 23;

[0030] (I) Optical path setup:

[0031] First, the output energy pulse of the femtosecond laser is adjusted by rotating the half-wave plate 3 in the pump light polarization and energy control component. The 800nm ​​femtosecond laser 1 is split into two pump lights with similar energy by a 50 / 50 splitter and the first beam splitter 5. The pump lights are guided by the high-reflectivity mirror 8 and uniformly polarized by the half-wave plate 7. One of the beams is controlled by the high-precision delay control component 9 (delay line 9) to achieve femtosecond-level relative time delay control.

[0032] Two parallel pump beams intersect at a small angle (θ ~ 2.29°) through a cross lens 13. The two beams are spatiotemporally overlapped by controlling a high-precision delay control component 9 (delay line 9), forming a thermal grating. The angle is determined by θ = 2arctan(d / 2f), where d is the lateral distance between the two parallel pump beams in front of the lens, and f is the focal length of the lens. The sampling mirror 22 reflects approximately 1% of the pump light energy, which is attenuated by a neutral density filter and then introduced into a CMOS camera 23 for imaging to obtain the two-dimensional plasma grating fringe structure, such as... Figure 3 As shown, the gray values ​​of the grating fringes are integrated horizontally and vertically to obtain the grating fringe spacing ∧, which provides a basis for calculating the incident Bragg angle of the probe light and deriving the theoretical expressions for temperature and pressure.

[0033] The 532nm continuous laser beam is split into a probe beam 10 and a tracking beam 11. The probe beam 10 is incident on the thermal grating at a Bragg angle θ2 to generate a femtosecond laser-induced grating scattering signal. The tracking beam 11 maintains its original path as a reference and is finely adjusted by a dichroic mirror 12. The two beams enter the grating region at Bragg angles, and their relative positions are as follows: Figure 1 As shown in the left illustration 24.

[0034] Since the pump light, probe light, and signal light are symmetrically positioned at the focal point of the cross lens 13, a cross lens 15 is placed at its symmetrical location to collimate the four beams and maintain parallelism in the far field. Their spatial distribution is as follows: Figure 1 As shown in right illustration 25, and used as a calibration reference.

[0035] (II) Signal Acquisition:

[0036] During the acquisition of femtosecond laser-induced grating scattering signals, an optical trap 16 is used to block the pump light, probe light, and stray light passing through the cross lens 15; the optical path is extended and introduced into a monochromator 19, with a narrow-band filter installed in front of its slit to effectively suppress stray light. The purified signal is then introduced into a photomultiplier tube (PMT) 20 and amplified by a preamplifier before being input into an oscilloscope 21 for real-time display and recording. During synchronous temperature and pressure measurement, an air-filled environmental control device 14 is placed at the grating intersection (e.g., ...). Figure 2 The temperature is regulated by an intelligent temperature controller, and a pressure gauge connected to the sealed tube furnace is used to record the pressure inside the tube at the corresponding temperature. Each time the temperature at the grating position is adjusted, the oscilloscope simultaneously captures the time-domain waveform of the laser-induced grating scattering signal (e.g., ...). Figure 4 Record the pressure inside the tube for subsequent analysis.

[0037] (III) Temperature Measurement

[0038] The time-domain evolution waveform of the femtosecond laser-induced grating scattering signal was processed by Fast Fourier Transform (FFT), and data from the start of the signal to 10% of its maximum value were selected for FFT processing to obtain the oscillation frequency f at different medium temperatures. osc (like Figure 5 ).

[0039] According to the oscillation frequency f osc Calculate the temperature. Laboratory air satisfies the ideal gas law, and the relationship between the oscillation frequency of the femtosecond laser-induced grating scattering signal and the temperature can be derived, as shown in equation (1).

[0040]

[0041] Where γ is the ratio of isobaric specific heat capacity to isovolumetric specific heat capacity, R is the universal gas constant, and M is the volumetric molecular weight of the mixture. γ can be obtained by consulting relevant databases. Measurement results are as follows: Figure 6 As shown, the vertical axis represents the temperature measured by the femtosecond laser-induced grating scattering signal, and the horizontal axis represents the thermocouple temperature. Its measurement accuracy and precision are between -0.1% and 0.1%, and between -5% and 5%, respectively. Figure 7 As shown, this result demonstrates the feasibility of fs-LIGS technology in temperature measurement.

[0042] (iv) Pressure measurement

[0043] We use the empirical expression proposed by Kozlov et al. to fit the time evolution of the femtosecond laser-induced grating scattering signal, which is shown in equation (2) below:

[0044]

[0045] Where S0 is the signal scaling factor, M i M f and M e All are dimensionless coefficients, f osc τ represents the oscillation frequency of a sound wave. tr τ represents the time required for a sound wave to travel from the detection area. th τ represents the attenuation constant of the stationary portion of a laser-induced grating affected by thermal diffusion. f k represents the decay time constant of rapid relaxation caused by molecular collisions. f =2πf osc τ f .

[0046] The fitting process uses nonlinear least squares and the Levenberg-Marquardt algorithm to fit the signal to the empirical expression (2). In the fitting, we consider the contributions of instantaneous and rapid energy distributions and electrostriction effects to the femtosecond laser-induced grating scattering signal; the initial values ​​of all parameters are estimated from the original data. osc The initial value is set to the FFT frequency of the signal; τ is estimated based on the cumulative time of the first peak of the signal. f The initial value; from the perspective of the overall signal attenuation, τ is estimated. th The initial value, at which point the signal strength has decreased to 1% of its maximum value; S0, M i M f M e The initial values ​​of all parameters are set to 1. The fitting quality is optimized by fine-tuning each parameter, thereby determining the parameter τ. th (like Figure 8 The optimal value is shown in the figure.

[0047] Based on the fitting parameter τ th Calculate the pressure. Since τ th This characterizes the thermal diffusion effect, which is related to the local density of the gas. Therefore, we can assume that the gas in the chamber satisfies the ideal gas law, and thus derive τ. th The relationship between air pressure and pressure is expressed as shown in equation (3).

[0048]

[0049] Wherein, the ideal gas constant R = 8.314 × 10 -5 m 3 ·bar·K -1 mol -1 The molar mass of air, M = 28.97 g / mol, κ is the thermal conductivity of air, κ = 0.026 W / mK at room temperature (25℃), c p This refers to the isobaric specific heat capacity of air. By consulting a database (The Engineering ToolBox), we performed an exponential fit on existing values ​​for the isobaric specific heat capacity of air. We then extracted τ from the fit. th Value and corresponding c p By combining these values, the pressure can be calculated. The measurement results are as follows: Figure 9 As shown, the vertical axis represents the measured pressure, and the horizontal axis represents the actual pressure measured by the barometer. The slope obtained by fitting the data is 0.993±0.07. The accuracy of pressure measurement using femtosecond laser-induced grating scattering signals is between -6% and 9%. Figure 10 As shown, its measurement precision and accuracy results demonstrate the feasibility of femtosecond laser-induced grating spectroscopy in pressure measurement.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology, characterized in that, It includes a laser source, a pump light polarization and energy control component, a first beam splitter (5), a second beam splitter (6), a polarization control component, a high-reflectivity mirror (8), a high-precision delay control component (9), an optical coupling component, an environmental control device (14), an optical path calibration and filtering component, a signal collection system, a sampling mirror (22), and a CMOS camera (23); The laser source is used to generate femtosecond pump light (1) and continuous probe light (2); the pump light polarization and energy control component is used to adjust the polarization state of the pump light and to adjust the total pump light energy; the first beam splitter (5) is used to split the pump light into two pump lights with equal energy; the polarization control component adjusts the half-wave plate (7) to make the two pump lights have the same polarization state after passing through the analyzer; the high-precision delay control component (9) is used to control the two pump pulses to achieve time coincidence on the femtosecond scale; the optical coupling component includes a first dichroic mirror (12) and a first cross lens (13), the first dichroic mirror (12) is used to realize the beam combining of pump light and probe light, the first cross lens (13) is used to focus the two pump lights at a small angle to cause interference and form a thermal grating, and at the same time focus the probe light; the environmental control device (14) is used to control the temperature and pressure at the position of the thermal grating; the optical path calibration and filtering component is used to adjust the propagation direction of the four beams and effectively block and filter stray light.

2. The synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology according to claim 1, characterized in that, The second beam splitter (6) is used to split the laser output from the continuous laser source at a ratio of 9:1, which are used as the probe light (10) and the tracking light (11). The probe light (10) is incident on the thermal grating at the Bragg first-order diffraction angle and is scattered, thereby generating a coherent femtosecond laser-induced grating spectroscopy signal light in the phase-matching direction. The tracking light (11) is used to track the propagation direction of the signal light and is turned off during measurement.

3. The synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology according to claim 2, characterized in that, The signal collection system includes a monochromator (19), a photomultiplier tube (20), and an oscilloscope (21). The monochromator (19) is used to further filter stray light, the photodetector (20) is used to convert the signal light into an electrical signal, and the oscilloscope (21) is used to record the time-domain evolution waveform of the femtosecond laser-induced grating spectral technology signal. The COMS camera (23) is used to acquire and process the grating fringe image to obtain the grating fringe spacing and further calculate the temperature and pressure parameters.

4. The synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology according to claim 1, characterized in that, The laser source includes a Ti:sapphire femtosecond laser with a center wavelength of 800 nm and a continuous laser with a center wavelength of 532 nm. The two pump beams generated by the femtosecond laser interfere in the intersection region to form a laser-induced grating, and then form a thermal grating through energy deposition. The probe beam generated by the continuous laser is used to scatter with the thermal grating to generate a femtosecond laser-induced grating scattering signal.

5. The synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology according to claim 1, characterized in that, The pump light polarization and energy control component includes a half-wave plate (3) and a polarizing mirror (4). The half-wave plate (3) is used to change the polarization state of the pump light, and the polarizing mirror (4) is used to selectively transmit horizontally polarized pump light, thereby adjusting the total pump light energy by rotating the half-wave plate (3).

6. The synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology according to claim 1, characterized in that, The high-precision delay control component (9) includes a precision electric displacement slide and two height reflectors.

7. The synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology according to claim 1, characterized in that, The environmental control device (14) includes a tubular furnace, a gas supply line, a water cooling line, and a pressure measuring device. The tubular furnace is temperature-regulated by an intelligent temperature controller. The maximum operating temperature is 1200℃ and the rated power is 1200W. Quartz windows are installed at both ends of the tubular furnace for gas filling and evacuation operations. The tubular furnace can withstand a gas pressure of 5 atmospheres. The pressure gauge is connected to the sealed tubular furnace and is used to record the gas pressure inside the tube.

8. The synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology according to claim 1, characterized in that, The optical path calibration and filtering assembly includes a second cross lens (15), an optical trap (16), and a second dichroic mirror (17). The second cross lens (15) is used to collimate four beams of light so that their propagation direction is horizontal. The four beams of light are two pump beams, a probe beam, and a signal beam. The optical trap (16) is used to block the pump beam and probe beam that pass through the second cross lens (15). The second dichroic mirror (17) is also used to reflect the signal beam and transmit the pump beam.

9. A synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology according to claim 3, characterized in that, The signal collection system first collimates the scattered signal through a cross lens (18), and after multiple reflections, it enters a monochromator (19) to further filter stray light. Then the signal enters a photomultiplier tube, where the optical signal is converted and amplified into an electrical signal. Finally, the time-domain evolution waveform of the scattered signal is collected by an oscilloscope.

10. A synchronous temperature and pressure measurement device based on femtosecond laser-induced grating spectroscopy technology according to claim 1, characterized in that, The CMOS camera (23) acquires and processes the grating stripe image to obtain the grating stripe spacing and further calculates the temperature and pressure parameters.

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