A high-frequency response thermal flow sensor calibration device and calibration method

Abstract

The present invention discloses a high-frequency response heat flux sensor calibration device and calibration method, including: a laser, which is built with an aspheric lens group system and a high-frequency driving board; a 4f imaging system, which is arranged in the laser emission direction of the collimating lens; a primary spectroscopic module; a secondary spectroscopic module; a photodetector, whose position is aligned with one spectroscopic optical path of the secondary spectroscopic module; a feeding platform, whose position is aligned with another spectroscopic optical path of the primary spectroscopic module, and the feeding platform is fixed with a standard heat flux sensor and a heat flux sensor to be calibrated through a sensor fixture; a camera, which is connected to a measurement and control computer; a function generator, which is respectively connected to the laser and the measurement and control computer; a phase-locked amplifier, which is respectively connected to the feeding platform, the function generator and the measurement and control computer. The high-frequency response heat flux sensor calibration device provided by the present invention obtains a stable, uniform, continuously adjustable high-frequency response laser heat source, and adopts a comparison calibration method to realize the calibration and detection of the high-frequency response heat flux sensor.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-frequency response thermal flow sensor calibration, and more specifically, the present invention relates to a high-frequency response thermal flow sensor calibration device and a calibration method. Background Art

[0002] With the development of high-performance aircraft, the accurate estimation of its surface mechanical and thermal parameters is becoming more and more important, especially the prediction of the transition zone, because when the laminar flow turns into turbulent flow, the local friction and heat flow will change greatly. In order to capture the subtle changes in these boundary layers, high-frequency response heat flux sensors are usually used to measure the pulsating heat flux on the aircraft surface. In order to obtain the accurate value of the high-frequency pulsating heat flux (above 100kHz) on the aircraft surface, the frequency response characteristics of the heat flux sensor used must be calibrated, and the heat flux sensor calibration device needs to cover the measured pulsating frequency range. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0004] In order to achieve these purposes and other advantages according to the present invention, a high-frequency response thermal flow sensor calibration device is provided, comprising:

[0005] A laser, wherein an aspheric lens group system is arranged inside, wherein the aspheric lens group system comprises an aspheric lens and a collimating lens close to the laser light source; and a high-frequency laser driving board with a large current is arranged inside the laser;

[0006] A 4f imaging system is arranged in the laser emission direction of the collimating lens; a primary light splitting module is aligned with the emission port of the 4f imaging system; and a secondary light splitting module is aligned with a light splitting path of the primary light splitting module;

[0007] A photoelectric detector is aligned with one of the split light paths of the secondary split light module; a feeding platform is aligned with another split light path of the primary split light module, and the feeding platform is fixed with a standard heat flux sensor and a heat flux sensor to be calibrated through a sensor fixture; a camera is arranged on another split light path of the secondary split light module, and the camera is connected to a measurement and control computer through a cable;

[0008] A function generator is connected to the laser and the measurement and control computer through cables respectively; a phase-locked amplifier is connected to the feeding platform, the function generator and the measurement and control computer through cables respectively.

[0009] Preferably, the laser generates a laser beam with a Gaussian distribution of irradiance, and the aspheric lens group system shapes the laser beam with a Gaussian distribution of irradiance into a uniform beam, that is, the incident laser beam is first modulated by the aspheric lens of the aspheric lens group system, and then a nearly flat-top beam with uniform irradiance distribution is obtained at the collimating lens position.

[0010] Preferably, the laser is a high-frequency response fiber laser;

[0011] The primary light splitting module and the secondary light splitting module are light splitting lenses.

[0012] Preferably, the structure of the feeding platform includes:

[0013] A fixed base, on which three parallel longitudinal guide rails are fixedly arranged; a slider I is slidably arranged on the longitudinal guide rail, and a transverse guide rail is integrally formed on the slider I; a slider II is slidably arranged on the transverse guide rail, and a plurality of sensor fixtures are fixedly arranged on the slider II;

[0014] A stepper motor I, which is fixedly arranged on one side of the fixed base, wherein the output shaft of the stepper motor I is fixedly connected to a screw rod I, a ball screw nut I is fixedly arranged in the slider I, and the ball screw nut I is sleeved on the screw rod I;

[0015] A stepper motor II is fixedly arranged at one end of the transverse guide rail, the output shaft of the stepper motor II is fixedly connected with a screw rod II, a ball screw nut II is fixedly arranged in the slider II, and the ball screw nut II is sleeved on the screw rod II.

[0016] Preferably, the 4f imaging system comprises lens I and lens II fixed by a bracket, wherein lens I is located between lens II and the laser.

[0017] A high-frequency response heat flow sensor calibration method comprises the following steps:

[0018] Step 1: Install the standard heat flow sensor and the heat flow sensor to be calibrated on the delivery platform, check all water connections and line connections, and turn on the fiber laser after confirming that there are no problems;

[0019] Step 2: Check the beam distribution data collected by the camera. If the beam distribution satisfies the unevenness less than 3%, proceed to step 3. Otherwise, the optical path system needs to be adjusted.

[0020] Step 3: Carry out steady-state calibration: Align the standard heat flux sensor with the main optical path of the primary spectrometer module, use the standard heat flux sensor to detect the spot irradiance, that is, the heat flux density, adjust the fiber laser to steady-state output, and the power is the appropriate value P. At this time, the heat flux density measured by the standard heat flux sensor is q stdTemporarily turn off the fiber laser, direct the heat flux sensor to be calibrated to the quasi-main optical path of the primary light splitting module, and then set the fiber laser so that the fiber laser power value is the same as the power value when irradiating the standard heat flux sensor, that is, set the fiber laser power value to P again, and also to steady-state output, and then turn on the fiber laser to obtain the thermoelectric potential output U of the sensor to be calibrated test ;

[0021] Step 4: Repeat step 3 5 times, and set the laser power value to a different value each time as needed, and then you can get X = {0, U test1 , U test2 , U test3 , U test4 , U test5}, Y = {0, q std1 ,q std2 ,q std3 ,q std4 ,q std5}, then take the value of X as the independent variable and the value of Y as the dependent variable for linear fitting. The slope value η after fitting is the sensitivity coefficient of the heat flow sensor to be calibrated;

[0022] Step 5: Conduct frequency response analysis: Select a reference power p from the five different power values ​​in step 4. i , the measured heat flux of the heat flux sensor to be calibrated is q testi , set the initial frequency of the fiber laser to f0, the waveform to a sine wave, and the power to p i , collect the output amplitude value of the heat flow sensor to be calibrated like If the error is less than the acceptable error ε, the frequency will continue to increase, generally by 10 times each time, until the maximum frequency f that meets the acceptable error ε is found. max ; By setting the function generator to output a sinusoidal signal with a positive base deviation to drive the fiber laser, a sinusoidal laser incident heat flux waveform at the same frequency is obtained, and the function of detecting the frequency response characteristics of the heat flux sensor to be calibrated is realized. The specific process includes: firstly, the function generator is set with an initial low-frequency f0 positive base deviation sinusoidal signal, which is usually not greater than one thousandth of the estimated cutoff frequency of the heat flux sensor, or can be set to 100Hz for a high-frequency sensor, to drive the fiber laser, and the phase-locked amplifier synchronously detects the output signal of the function generator and the output signal of the heat flux sensor to be calibrated to obtain the sinusoidal signal amplitude V0 of the heat flux sensor to be calibrated; only the output frequency f0 of the function generator is gradually increased. i (i=1,2,3,…), the sinusoidal amplitude of the output signal of the heat flow sensor is detected by the phase-locked amplifier The cutoff frequency of the heat flow sensor is determined according to the following formula:

[0023]

[0024] Thus, the thermal flow test frequency response range of the thermal flow sensor can be detected.

[0025] Preferably, in the step three, the method for aligning the standard heat flux sensor or the heat flux sensor to be calibrated with the main light path of the first-level spectrometer module is: turning on the stepper motor II, and the stepper motor II drives the screw rod II to rotate, so that the slider II moves laterally along the transverse guide rail, so that the standard heat flux sensor or the heat flux sensor to be calibrated clamped on the sensor fixture can be aligned with the main light path of the first-level spectrometer module; at the same time, by turning on the stepper motor I, the longitudinal position of the standard heat flux sensor and the heat flux sensor to be calibrated can be adjusted.

[0026] The present invention includes at least the following beneficial effects: the high-frequency response heat flux sensor calibration device provided by the present invention adopts a fiber laser with a driving version containing a large current, and uses a 4f system to transmit and shape the uniform laser wave surface, thereby obtaining a stable, uniform, and continuously adjustable high-frequency response laser heat source. Based on this light source, a comparison calibration method is used to realize the calibration and detection of high-frequency response heat flux sensors within 1 MHz. The highest laser heat source frequency can reach 1 MHz, and the fastest response time is less than 100 ns, filling the gap in the domestic high-speed dynamic sensor calibration and detection.

[0027] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a high-frequency response thermal flow sensor calibration device according to a preferred embodiment of the present invention;

[0029] Figure 2 A schematic diagram of the structure of the feeding platform provided by the present invention;

[0030] Figure 3 A schematic diagram of the structure of the aspheric lens assembly system provided by the present invention;

[0031] Figure 4 This is a schematic diagram of the imaging principle of the 4f imaging system provided by the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0033] It should be understood that terms such as “having”, “including” and “comprising” used herein do not specify the existence or addition of one or more other elements or combinations thereof.

[0034] It should be noted that in the description of the present invention, the orientation or positional relationship indicated by the term is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present invention, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In addition, in the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0037] like Figure 1-4 As shown: A high-frequency response heat flow sensor calibration device of the present invention comprises:

[0038] A laser 1 is provided with an aspheric lens group system inside, wherein the aspheric lens group system includes an aspheric lens F1 and a collimating lens F2 close to the laser light source; a high-frequency laser driving board with a large current is configured inside the laser 1;

[0039] 4f imaging system 2, which is arranged in the laser emission direction of the collimating lens F2; ​​a primary light splitting module 3, which is aligned with the emission port of 4f imaging system 2; a secondary light splitting module 4, which is aligned with a light splitting path of the primary light splitting module 3;

[0040] A photoelectric detector 5 is aligned with one of the split light paths of the secondary split light module 4; a feeding platform 6 is aligned with another split light path of the primary split light module 3, and the feeding platform 6 is fixed with a standard heat flux sensor and a heat flux sensor to be calibrated through a sensor fixture; a camera 7 is arranged on another split light path of the secondary split light module 4, and the camera 7 is connected to a measurement and control computer 8 through a cable;

[0041] A function generator 9 is connected to the laser 1 and the measurement and control computer 8 through cables; a phase-locked amplifier 10 is connected to the feeding platform 6, the function generator 9 and the measurement and control computer 8 through cables.

[0042] Working principle: The laser 1 generates a laser beam with a Gaussian irradiance distribution, and the aspheric lens group system shapes the laser beam with a Gaussian irradiance distribution into a uniform beam, that is, the incident laser beam is first modulated by the aspheric lens F1 of the aspheric lens group system, and then a nearly flat-top beam with uniform irradiance distribution is obtained at the position of the collimating lens F2. The collimating lens F2 has two functions. One is to collimate the relatively uniform nearly flat-top beam into parallel light. The second function is that the outgoing beam will have a certain light mixing effect during the collimation process. At a specific working distance (BFL of the collimating lens F2), the nearly flat-top light will be further homogenized to obtain a flat-top light that meets the unevenness index. In order to ensure that the laser can reach an output power of 2W at a driving frequency of 1MHz, it is equipped with a high-frequency driving board with a large current, wherein the current can reach more than 3A, and the driving board frequency is 1MHz, ensuring that the laser can output 2W power at 1MHz; after the light beam comes out of the laser 1, it successively enters the 4f imaging system 2, the primary spectroscopic module 3, the secondary spectroscopic module 4, the feeding platform 6, the camera 7 and the photoelectric detector 5; the 4f imaging system 2 is used to perform secondary homogenization on the light beam to expand and contract the beam diameter, so that the final unevenness and spot size of the light beam meet the use requirements. The primary spectroscopic module 3 allows most of the light energy to enter the standard heat flux sensor and the heat flux sensor to be calibrated on the feeding platform 6, and a very small part of the light enters the secondary spectroscopic module 4; the secondary spectroscopic module 4 allows part of the light energy to enter the camera 7, and the other part enters the photoelectric detector 5. The splitting ratio of the primary splitter module 3 and the secondary splitter module 4 needs to be specifically designed according to the response sensitivity of the beam receiver of the main optical path and the splitter path. The beam entering the direction of the feeding platform 6 is the main optical path, and the beam entering the camera 7 and the photodetector 5 is the splitter path. According to the safety threshold of the response sensitivity of the beam receiver of the splitter path, the splitting ratio of the primary splitter module and the secondary splitter module is adjusted to ensure that the beam receiver can detect the weak light irradiation of the splitter path and the beam receiver is not burned by the laser. The feeding platform 6 is used to clamp and install the standard heat flux sensor and the heat flux sensor to be calibrated. During calibration, the specific positions of the standard heat flux sensor and the heat flux sensor to be calibrated can be moved to align the laser beam. The camera 7 is used to detect the unevenness of the light beam. The photodetector 5 is used to synchronously monitor the high-frequency dynamic irradiation waveform of the light beam. The function generator 9 is used to provide a high-frequency signal source to the high-frequency driving board of the laser 1, and at the same time provide a reference base signal to the phase-locked amplifier 10. The lock-in amplifier 10 is used to obtain the weak output high-frequency signal of the heat flow sensor to be calibrated, and supports the evaluation of the frequency response characteristics of the heat flow sensor to be calibrated, including amplitude-frequency and phase-frequency response detection.The measurement and control computer 8 is respectively connected to the laser 1, the feeding platform 6, the standard heat flux sensor, the heat flux sensor to be calibrated, the camera 7, the photoelectric detector 5, the phase-locked amplifier 10 and the function generator 9, and is used to control the beam output of the laser 1 and the movement of the feeding platform 6 and to collect the output signals of the camera 7, the photoelectric detector 5, the standard heat flux sensor and the heat flux sensor to be calibrated. The high-frequency response heat flux sensor calibration device provided by the present invention has a maximum laser heat source frequency of 1MHz and a fastest response time of less than 100ns, filling the gap in the calibration and detection of domestic high-speed dynamic heat flux sensors.

[0043] In the above technical solution, the laser 1 is a 2W fiber laser with a 1MHz driver board with a large current. An aspheric lens group system is used to homogenize the transmission path from the fiber light source to the fiber head. The light beam coming out of the fiber head already has a laser wavefront that meets the uniformity index.

[0044] The primary light splitting module 3 and the secondary light splitting module 4 are light splitting lenses.

[0045] In the above technical solution, the structure of the feeding platform 6 includes:

[0046] A fixed base 11, on which three parallel longitudinal guide rails 12 are fixedly arranged; a slider I 13 is slidably arranged on the longitudinal guide rail 12, and a transverse guide rail 14 is integrally formed on the slider I 13; a slider II 15 is slidably arranged on the transverse guide rail 14, and two sensor fixtures 16 are fixedly arranged on the slider II 15, which are respectively used to fix the standard heat flow sensor and the heat flow sensor to be calibrated;

[0047] A stepper motor Ⅰ17 is fixedly arranged on one side of the fixed base 11, the output shaft of the stepper motor Ⅰ17 is fixedly connected to a screw rod Ⅰ18, a ball nut Ⅰ19 is fixedly arranged in the slider Ⅰ13, and the ball nut Ⅰ19 is sleeved on the screw rod Ⅰ18;

[0048] The stepper motor II20 is fixedly arranged at one end of the transverse guide rail 14, and the output shaft of the stepper motor II20 is fixedly connected with a screw rod II21, and the slider II15 is fixedly provided with a ball screw nut II22, and the ball screw nut II22 is sleeved on the screw rod II21. When the stepper motor II20 is turned on, the stepper motor II20 drives the screw rod II21 to rotate, so that the slider II15 moves laterally along the transverse guide rail 14, and the standard heat flux sensor or the heat flux sensor to be calibrated clamped on the sensor fixture 16 can be aligned with the main optical path of the primary spectrometer module 5; at the same time, by turning on the stepper motor I17, the stepper motor I17 drives the screw rod I18 to rotate, so that the slider I13 moves longitudinally along the longitudinal guide rail 13, and the longitudinal position of the standard heat flux sensor and the heat flux sensor to be calibrated can be adjusted.

[0049] In the above technical solution, the 4f imaging system includes a lens IF3 and a lens II fixed by a bracket, wherein the lens IF3 is located between the lens IIF4 and the laser. Figure 4 As shown, A is a uniform light spot that has met the homogenization index. Through the real focus 4f system composed of lens IF3 and lens IF4, this uniform light spot surface can be transferred to a specified distance to form a smaller light spot B that also meets the homogenization index.

[0050] A high-frequency response heat flow sensor calibration method comprises the following steps:

[0051] Step 1: Install the standard heat flow sensor and the heat flow sensor to be calibrated on the feeding platform 6, check all water connections and line connections, and turn on the fiber laser 1 after confirming that there are no problems;

[0052] Step 2: Check the beam distribution data collected by the camera 7. If the beam distribution satisfies the unevenness less than 3%, proceed to step 3. Otherwise, the optical path system needs to be adjusted.

[0053] Step 3: Carry out steady-state calibration: Align the standard heat flux sensor with the main optical path of the primary spectrometer module 3, use the standard heat flux sensor to detect the spot irradiance, that is, the heat flux density, adjust the fiber laser 1 to a steady-state output, and the power is an appropriate value P. At this time, the heat flux density measured by the standard heat flux sensor is q std Temporarily turn off the fiber laser 1, direct the heat flux sensor to be calibrated to the main optical path of the primary light splitting module 3, and then set the fiber laser 1 so that the fiber laser power value is the same as the power value when irradiating the standard heat flux sensor, that is, the fiber laser power value is set to P again, and it is also a steady-state output, and then turn on the fiber laser 1 to obtain the thermoelectric potential output U of the sensor to be calibrated test ;

[0054] Step 4: Repeat step 3 5 times, and set the laser power value to a different value each time as needed, and then you can get X = {0, U test1 , U test2 , U test3 , U test4 , U test5}, Y = {0, q std1 ,q std2 ,q std3 ,q std4 ,q std5}, then use the value of X as the independent variable and the value of Y as the dependent variable for linear fitting. The slope value η after fitting is the sensitivity coefficient of the heat flow sensor to be calibrated. When calibrating a Schmidit-Boelter heat flow sensor, we get: X = {0, 0.1426, 0.1827, 0.228, 0.2776, 0.336}, in mV; Y = {0, 31.2465, 39.738, 49.839, 60.606, 72.6459}, in kW / m 2 , then the linear fitting can be obtained to obtain the sensitivity coefficient of the heat flow sensor to be calibrated as 217.53kW / m 2 / mV;

[0055] Step 5: Conduct frequency response analysis: Select a reference power p from the five different power values ​​in step 4. i , the measured heat flux of the heat flux sensor to be calibrated is q testi , set the initial frequency value of fiber laser 1 to f0, the waveform to sine wave, and the power to p i , collect the output amplitude value of the heat flow sensor to be calibrated like If the error is less than the acceptable error ε, the frequency will continue to increase, generally by 10 times each time, until the maximum frequency f that meets the acceptable error ε is found. max ; By setting the function generator 9 to output a sinusoidal signal with a positive base deviation to drive the fiber laser 1, a sinusoidal laser incident heat flux waveform at the same frequency is obtained, and the function of detecting the frequency response characteristics of the heat flux sensor to be calibrated is realized. The specific process includes: firstly, the function generator is set to have an initial low-frequency f0 positive base deviation sinusoidal signal, which is usually not greater than one thousandth of the estimated cutoff frequency of the heat flux sensor to be calibrated, or can be set to 100 Hz for a high-frequency sensor, to drive the fiber laser 1, and the phase-locked amplifier 10 synchronously detects the output signal of the function generator 9 and the output signal of the heat flux sensor to be calibrated, and obtains the sinusoidal signal amplitude V0 of the heat flux sensor to be calibrated; only the output frequency f0 of the function generator is gradually increased. i (i=1,2,3,…), the sinusoidal amplitude of the output signal of the heat flow sensor is detected by the phase-locked amplifier The cutoff frequency of the heat flow sensor is determined according to the following formula:

[0056]

[0057] Thus, the thermal flow test frequency response range of the thermal flow sensor can be detected.

[0058] In summary, the high-frequency response heat flux sensor calibration device provided by the present invention adopts a 2W fiber laser with a 1MHz driving version containing a large current, and uses a 4f system to transmit and shape the uniform laser wavefront, thereby obtaining a stable, uniform, and continuously adjustable high-frequency response laser heat source. Based on this light source, a comparison calibration method is used to realize the calibration and detection of high-frequency response heat flux sensors within 1MHz.

[0059] In the above technical scheme, the method for aligning the standard heat flux sensor or the heat flux sensor to be calibrated with the main optical path of the first-level spectrometer module in step three is: turn on the stepper motor II20, and the stepper motor II20 drives the screw rod II21 to rotate, so that the slider II15 moves laterally along the transverse guide rail 14, and the standard heat flux sensor or the heat flux sensor to be calibrated clamped on the sensor fixture 16 can be aligned with the main optical path of the first-level spectrometer module 5; at the same time, by turning on the stepper motor I17, the stepper motor I17 drives the screw rod I18 to rotate, so that the slider I13 moves longitudinally along the longitudinal guide rail 13, and the longitudinal position of the standard heat flux sensor and the heat flux sensor to be calibrated can be adjusted.

[0060] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0061] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A high-frequency response thermal flow sensor calibration method, characterized in that: The high-frequency response heat flow sensor calibration device used includes: A laser, wherein an aspheric lens group system is arranged inside, wherein the aspheric lens group system comprises an aspheric lens and a collimating lens close to the laser light source; and a high-frequency laser driving board with a large current is arranged inside the laser; A 4f imaging system, which is arranged in the laser emission direction of the collimating lens; a primary light splitting module, which is located at the emission port of the 4f imaging system; and a secondary light splitting module, which is aligned with a light splitting path of the primary light splitting module; A photoelectric detector is aligned with one of the split light paths of the secondary split light module; a feeding platform is aligned with another split light path of the primary split light module, and the feeding platform is fixed with a standard heat flux sensor and a heat flux sensor to be calibrated through a sensor fixture; a camera is arranged on another split light path of the secondary split light module, and the camera is connected to a measurement and control computer through a cable; A function generator, which is connected to the laser and the measurement and control computer through cables; a lock-in amplifier, which is connected to the feeding platform, the function generator and the measurement and control computer through cables; The high-frequency response heat flow sensor calibration method includes the following steps: Step 1: Install the standard heat flow sensor and the heat flow sensor to be calibrated on the delivery platform, check all water connections and line connections, and turn on the fiber laser after confirming that there are no problems; Step 2: Check the beam distribution data collected by the camera. If the beam distribution satisfies the unevenness less than 3%, proceed to step 3. Otherwise, the optical path system needs to be adjusted. Step 3: Carry out steady-state calibration: Align the standard heat flux sensor with the main optical path of the primary spectrometer module, use the standard heat flux sensor to detect the spot irradiance, that is, the heat flux density, and adjust the fiber laser to a steady-state output with an appropriate power value. P At this time, the heat flux density measured by the standard heat flux sensor is q std ; Temporarily turn off the fiber laser, align the heat flux sensor to be calibrated with the main optical path of the primary light splitting module, and then set the fiber laser so that the fiber laser power value is the same as the power value when irradiating the standard heat flux sensor, that is, set the fiber laser power value to P， And it is also a steady-state output, then turn on the fiber laser to obtain the thermoelectric potential output of the sensor to be marked U test ; Step 4: Repeat step 3 5 times, and set the laser power value to a different value each time as needed, and then you can get X={0, U test1 , U test2 , U test3 , U test4 , U test4 },Y={0, q std1 , q std2 , q std3 , q std4 , q std5 }, then use the value of X as the independent variable and the value of Y as the dependent variable to perform a linear fit. The slope value after fitting is η It is the sensitivity coefficient of the heat flow sensor to be calibrated; Step 5: Conduct frequency response analysis: Select a reference power from the five different power values ​​in step 4. p i , the measured heat flux of the heat flux sensor to be calibrated is q testi , set the initial frequency value of the fiber laser to f 0, the waveform is a sine wave, and the power is p i , collect the output amplitude value of the heat flow sensor to be calibrated ,like Less than acceptable error ε , then continue to increase the frequency, each time by 10 times, until a value that satisfies the acceptable error is found. ε Maximum frequency f max ; By setting the function generator to output a sinusoidal signal with a positive base deviation to drive the fiber laser, a sinusoidal laser incident heat flux waveform at the same frequency is obtained to realize the function of detecting the frequency response characteristics of the heat flux sensor to be calibrated. The specific process includes: firstly, setting the initial low frequency of the function generator f 0 positive base biased sine signal, no more than one thousandth of the estimated cutoff frequency of the heat flow sensor, or set to 100Hz for high-frequency sensors, drives the fiber laser, and the phase-locked amplifier synchronously detects the output signal of the function generator and the output signal of the heat flow sensor to be calibrated to obtain the sine signal amplitude of the heat flow sensor to be calibrated V 0; only gradually increase the function generator output frequency f i ,in i =1,2,3,…, the sinusoidal amplitude of the output signal of the heat flow sensor is detected by the phase-locked amplifier ; Determine the cutoff frequency of the heat flow sensor according to the following formula: Thus, the thermal flow test frequency response range of the thermal flow sensor can be detected.

2. The high-frequency response thermal flow sensor calibration method according to claim 1, characterized in that: The laser generates a laser beam with a Gaussian irradiance distribution, and the aspheric lens group system shapes the laser beam with a Gaussian irradiance distribution into a uniform beam, that is, the incident laser beam is first modulated by the aspheric lens of the aspheric lens group system, and then a nearly flat-top beam with uniform irradiance distribution is obtained at the collimating lens position.

3. The high-frequency response thermal flow sensor calibration method according to claim 1, characterized in that: The laser is a high-frequency-response fiber laser; The primary light splitting module and the secondary light splitting module are light splitting lenses.

4. The high-frequency response thermal flow sensor calibration method according to claim 1, characterized in that: The structure of the feeding platform comprises: A fixed base, on which three parallel longitudinal guide rails are fixedly arranged; a slider I is slidably arranged on the longitudinal guide rail, and a transverse guide rail is integrally formed on the slider I; a slider II is slidably arranged on the transverse guide rail, and a plurality of sensor fixtures are fixedly arranged on the slider II; A stepper motor I, which is fixedly arranged on one side of the fixed base, wherein the output shaft of the stepper motor I is fixedly connected to a screw rod I, a ball screw nut I is fixedly arranged in the slider I, and the ball screw nut I is sleeved on the screw rod I; A stepper motor II is fixedly arranged at one end of the transverse guide rail, the output shaft of the stepper motor II is fixedly connected with a screw rod II, a ball screw nut II is fixedly arranged in the slider II, and the ball screw nut II is sleeved on the screw rod II.

5. The high-frequency response thermal flow sensor calibration method according to claim 1, characterized in that: The 4f imaging system comprises a lens I and a lens II fixed by a bracket, wherein the lens I is located between the lens II and the laser.

6. The high-frequency response thermal flow sensor calibration method according to claim 1, characterized in that: The method for aligning the standard heat flux sensor or the heat flux sensor to be calibrated with the main optical path of the primary spectrometer module in the step three is: turning on the stepper motor II, and the stepper motor II drives the screw rod II to rotate, so that the slider II moves laterally along the transverse guide rail, so that the standard heat flux sensor or the heat flux sensor to be calibrated clamped on the sensor fixture can be aligned with the main optical path of the primary spectrometer module; at the same time, by turning on the stepper motor I, the longitudinal position of the standard heat flux sensor and the heat flux sensor to be calibrated can be adjusted.

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