A thin film thermal diffusivity measurement system and method based on a variable radius ring laser heat source

Abstract

The application provides a thin film thermal diffusivity measurement system based on a variable radius annular laser heat source, and relates to the technical field of thin film material thermal diffusivity measurement. The method comprises the following steps: converting an electronic cosine signal into an electric signal for driving an acousto-optic modulator; modulating a Gaussian laser into an annular laser spot; continuously programming phase modulation on the annular laser spot, and using a liquid crystal spatial light modulator to complete non-contact, non-mechanical dynamic adjustment and real-time heat source center position adjustment; collecting temperature response data; receiving and storing the temperature response data output by a signal collection module, and obtaining a thermal diffusivity value after processing. The application can significantly improve the non-destructiveness and high signal-to-noise ratio of the temperature measurement process, solve the problems of complex processing steps and high measurement difficulty in pretreatment, realize the rapid and accurate thermal diffusivity measurement of conductive materials, and simultaneously measure insulating materials and conductive materials.

Description

Technical Field

[0001] This invention relates to the field of thermal diffusivity measurement technology for thin film materials, and in particular to a system and method for measuring the thermal diffusivity of thin films based on a variable radius annular laser heat source. Background Technology

[0002] Thermal diffusivity, as a crucial parameter of a material's thermal properties, measures its ability to maintain a uniform internal temperature. With the miniaturization and integration of microelectronic devices, their packaging density and operating frequency are constantly increasing, resulting in a significant amount of heat generated within the devices. If this heat cannot be dissipated quickly and effectively, it will damage the structure of electronic devices and components, affecting their performance and lifespan. This is especially true for thin-film materials, which are widely used in electronics, new energy batteries, and optics, where thermal diffusivity directly impacts the heat dissipation efficiency of semiconductor chips and the stability of photothermal coatings. Therefore, measuring the thermal diffusivity of thin-film materials is of practical significance for solving heat dissipation and thermal management problems.

[0003] The main methods for measuring thermal diffusivity are unsteady-state methods, also known as transient methods, including pulsed laser methods, the 3ω method, Raman spectroscopy, and planar heat source methods. These methods do not require waiting for the material to reach a steady state, have short measurement times, and calculate thermal diffusivity by measuring the dynamic change of temperature over time through periodic or instantaneous heat flow. This reduces errors caused by heat loss in thin film materials and is currently the most commonly used method for measuring the thermal diffusivity of thin film materials.

[0004] Transient methods, such as pulsed laser methods, are widely applicable to various metals and semiconductor materials, offering short testing times, but they can easily damage samples and have strict requirements on sample size and shape. The 3ω method, while highly accurate, is difficult to measure highly conductive thin films, has extremely high requirements for metal deposition processes, and is costly. Raman spectroscopy is a non-contact, non-destructive measurement method, well-suited for measuring the thermal diffusivity of micro / nano-scale thin film materials, but the results depend on the stability of Raman peaks, and experimental data processing is complex. Planar heat source methods offer fast measurement speed, high efficiency, and low cost, but poor heat flow uniformity can easily lead to heat source boundary effects. Using a ring light source can maximize the total heating power without increasing the overall power, significantly improving the signal-to-noise ratio and thus measurement accuracy. Summary of the Invention

[0005] To address the technical problems of complex pretreatment steps, high measurement difficulty, and excessively long measurement time for the thermal transport properties of short thin films in existing technologies, this invention provides a thin film thermal diffusivity measurement system and method based on a variable radius annular laser heat source. The technical solution is as follows:

[0006] On the one hand, a thin film thermal diffusivity measurement system based on a variable radius annular laser thermal source is provided, the system comprising: The signal generation module is used to convert electronic cosine signals into amplified electrical signals that drive the acousto-optic modulator; The modulation module is used to modulate the Gaussian laser beam into a ring laser spot, thereby obtaining the expanded beam. The dynamic adjustment module is used to dynamically and continuously programmably modulate the phase of the ring laser spot. The programmable phase modulation includes non-contact and non-mechanical dynamic adjustment and real-time adjustment of the center position of the heat source through a liquid crystal spatial light modulator to obtain the heating area corresponding to the ring spot. The signal acquisition module is used to collect temperature response data of the heating area; The thermal diffusivity calculation module is used to receive and store the temperature response data output by the signal acquisition module, and then process it to obtain the thermal diffusivity value.

[0007] Preferably, the signal generating module is used to convert the electronic cosine signal into an amplified electrical signal to drive the acousto-optic modulator, comprising: A signal generator is used to generate cosine electrical signals. The driver of the acousto-optic modulator is used to amplify the cosine electrical signal to obtain an amplified electrical signal.

[0008] Preferably, the modulation module is used to modulate the Gaussian laser beam into a ring laser spot to obtain an expanded beam, including: Lasers are used to generate Gaussian beams; An acousto-optic modulator is used to modulate a Gaussian beam according to an amplified electrical signal to obtain a modulated beam. A laser beam expander is used to amplify a modulated light beam to obtain an expanded beam.

[0009] Preferably, the dynamic adjustment module is used to dynamically and continuously programmably modulate the annular laser spot. The programmable phase modulation includes non-contact and non-mechanical dynamic adjustment via a liquid crystal spatial light modulator and real-time adjustment of the heat source center position to obtain the heating area corresponding to the annular laser spot, including: A liquid crystal spatial light modulator is used to perform programmable phase modulation on the expanded beam to control the radius of the annular spot and adjust the center position of the heat source in real time to obtain the encoded beam. The programmable phase modulation includes non-contact adjustment, non-mechanical dynamic adjustment and real-time heat source center position adjustment. The lens group, comprising a combination of a conical lens A, a light-blocking plate, a focusing lens, and a conical lens B, is used to shape the encoded beam into a ring-shaped spot with a variable radius. The light-blocking plate is used to block part of the laser beam from passing through, ensuring that the laser forms a precise ring-shaped heating area on the sample surface.

[0010] Preferably, the liquid crystal spatial light modulator is used to perform programmable phase modulation on the expanded beam to control the radius of the annular spot and adjust the center position of the heat source in real time to obtain the encoded beam. The programmable phase modulation includes non-contact adjustment, non-mechanical dynamic adjustment, and real-time heat source center position adjustment, including: The phase loop diameter is updated in real time by changing the parameters of the phase function; The phase distribution that conforms to the phase ring diameter constraint is converted into a ring beam with a variable radius by using conical lens A, thereby controlling the radius of the ring beam. By adding a translation term to the phase function, the position of the heat source center is adjusted, the radius of the annular spot is controlled, and the encoded beam is obtained.

[0011] Preferably, the signal acquisition module is used to acquire temperature response data of the heating area, including: The sample unit includes a thin film sample, a tip thermocouple, and a sample stage, which are used to place the thin film sample and the tip thermocouple on the sample stage respectively; The adjustment unit is used to adjust the position of the thin film so that it is located at the focal plane of the lens group to ensure that the annular light spot is focused on the sample surface and to move the tip thermocouple so that the tip is precisely positioned at the center point of the thin film sample. The preamplifier is used to collect the electrical signal obtained by the periodic temperature change caused by the ring-shaped light spot, and amplify it to obtain the amplified signal. A lock-in amplifier is used to extract the temperature amplitude and phase of the amplified signal from noise using lock-in technology, thereby obtaining temperature response data.

[0012] Preferably, the thermal diffusivity calculation module is used to receive and store the temperature response data output by the signal acquisition module, and process it to obtain a thermal diffusivity value, including: The storage unit is used to receive and store temperature response data, and to correct and optimize the phase-locked temperature response data in combination with initial parameters to obtain optimized data. The calculation unit is used to import the optimized data and initial parameters into the thermal conduction model for error comparison, iteratively update the thermal diffusivity of the thin film, and finally obtain the thermal diffusivity of the thin film sample. One end of the calculation unit is connected to the signal generation module to control signal generation, and the other end is connected to the storage unit to perform rapid analysis and calculation on the optimized data.

[0013] On the other hand, a method for measuring the thermal diffusivity of thin films based on a variable-radius annular laser thermal source is provided, the method comprising: The electronic cosine signal is converted into an amplified electrical signal that drives the acousto-optic modulator; Modulation of a Gaussian laser beam into a ring laser beam yields an expanded beam; The ring laser spot is dynamically and continuously programmed with phase modulation. The programmable phase modulation includes non-contact and non-mechanical dynamic adjustment and real-time adjustment of the center position of the heat source through a liquid crystal spatial light modulator to obtain the heating area corresponding to the ring laser spot. Collect temperature response data of the heating area; The system receives and stores the temperature response data output by the signal acquisition module, and then processes it to obtain the thermal diffusivity value.

[0014] On the other hand, a thin film thermal diffusivity measurement device based on a variable radius ring laser thermal source is provided. The thin film thermal diffusivity measurement device based on a variable radius ring laser thermal source includes: a processor; a memory, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the system as described in any of the above-described methods for measuring the thermal diffusivity of a thin film based on a variable radius ring laser thermal source is implemented.

[0015] On the other hand, a computer-readable storage medium is provided, characterized in that the computer-readable storage medium stores program code, which can be invoked by a processor to execute the system as described in any one of claims 1 to 7.

[0016] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: Using a laser as the heat source, the laser beam is expanded sequentially by a laser beam expander, shaped into a ring laser by a conical lens, and then focused onto the surface of the thin-film sample to form ring laser heating. Simultaneously, a needle-tip thermocouple senses the temperature change at the center point of the sample caused by laser heating, and the converted electrical signal is amplified by a preamplifier and transmitted to a lock-in amplifier. By adjusting the spatial light modulator of the liquid crystal to change the radius of the heat source, the temperature amplitude and phase are fitted as curves of temperature change with the radius of the heat source to obtain the in-plane thermal diffusivity. This invention combines non-contact laser heating with contact thermocouple temperature measurement, avoiding contact thermal resistance and sample damage through non-contact thermal excitation, while accurately measuring local temperature signals by direct contact between the thermocouple and the sample surface. This invention has advantages such as high sensitivity and high accuracy, and solves problems such as poor sample measurement adaptability and uneven heat flow distribution.

[0017] This invention can significantly improve the non-destructive nature and high signal-to-noise ratio of the temperature measurement process, solve the problems of complex pretreatment steps, high measurement difficulty, and excessively long measurement time for thermal transport properties of short films, realize the ability to quickly and accurately measure the thermal diffusivity of conductive materials, and can simultaneously measure insulating and conductive materials. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a block diagram of a thin film thermal diffusivity measurement system based on a variable radius annular laser heat source provided in an embodiment of the present invention; Figure 2 This is a graph showing the amplitude and phase variations with the radius of the heat source under different thermal diffusivity according to the embodiments of the present invention. Figure 3 This is a flowchart of a thin film thermal diffusivity measurement method based on a variable radius annular laser heat source provided by an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a thin film thermal diffusivity measurement device based on a variable radius annular laser heat source provided in an embodiment of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0021] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0022] In the embodiments of this invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, they convey the same meaning. Similarly, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, they convey the same meaning.

[0023] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0024] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0025] This invention provides a thin-film thermal diffusivity measurement system based on a variable-radius ring laser heat source. This system can be implemented using a thin-film thermal diffusivity measurement device based on a variable-radius ring laser heat source, which can be a terminal or a server. Figure 1 The block diagram shown is for a thin film thermal diffusivity measurement system based on a variable radius annular laser thermal source. The processing flow of this system may include the following modules:

[0026] The signal generation module is used to convert electronic cosine signals into amplified electrical signals that drive the acousto-optic modulator; Preferably, it includes: A signal generator is used to generate cosine electrical signals. The driver of the acousto-optic modulator is used to amplify the cosine electrical signal to obtain an amplified electrical signal.

[0027] It should be noted that, in some embodiments, a driver for the acousto-optic modulator is provided between the signal generator and the acousto-optic modulator to amplify the weak electrical signal of the signal generator and drive the acousto-optic modulator. The modulation module is used to modulate the Gaussian laser beam into a ring laser spot, thereby obtaining the expanded beam. Preferably, it includes: Lasers are used to generate Gaussian beams; An acousto-optic modulator is used to modulate a Gaussian beam according to an amplified electrical signal to obtain a modulated beam. A laser beam expander is used to amplify a modulated light beam to obtain an expanded beam.

[0028] In some embodiments, a laser beam expander, a conical lens, and a lens are used to shape the laser beam. The laser beam is expanded by the laser beam expander to match the conical lens and shape it into a ring beam, which is then focused onto the surface of the thin film sample by the lens.

[0029] The dynamic adjustment module is used to dynamically and continuously programmably modulate the phase of the ring laser spot. The programmable phase modulation includes non-contact and non-mechanical dynamic adjustment and real-time adjustment of the center position of the heat source through a liquid crystal spatial light modulator to obtain the heating area corresponding to the ring spot. Preferably, it includes: A liquid crystal spatial light modulator is used to perform programmable phase modulation on the expanded beam to control the radius of the annular spot and adjust the center position of the heat source in real time to obtain the encoded beam. The programmable phase modulation includes non-contact adjustment, non-mechanical dynamic adjustment and real-time heat source center position adjustment. The lens group, comprising a combination of a conical lens A, a light-blocking plate, a focusing lens, and a conical lens B, is used to shape the encoded beam into a ring-shaped spot with a variable radius. The light-blocking plate is used to block part of the laser beam from passing through, ensuring that the laser forms a precise ring-shaped heating area on the sample surface.

[0030] Preferably, the programmable phase modulation includes: The phase loop diameter is updated in real time by changing the parameters of the phase function; The phase distribution that conforms to the phase ring diameter constraint is converted into a ring beam with a variable radius by using conical lens A, thereby controlling the radius of the ring beam.

[0031] By adding a translation term to the phase function, the position of the heat source center is adjusted, the radius of the annular spot is controlled, and the encoded beam is obtained.

[0032] In some embodiments, the liquid crystal spatial light modulator is placed between the laser beam expander and the conical lens A to receive the collimated laser beam and perform programmable phase modulation on its wavefront, thereby realizing non-contact, non-mechanical dynamic adjustment of the heat source radius and adjusting the center position of the heat source in real time to ensure that it is precisely aligned with the temperature measurement point of the thermocouple probe, thus achieving center alignment and replacing the traditional mechanical displacement method, significantly improving the system response speed. The signal acquisition module is used to collect temperature response data of the heating area; Preferably, it includes: The sample unit includes a thin film sample, a tip thermocouple, and a sample stage, which are used to place the thin film sample and the tip thermocouple on the sample stage respectively; The adjustment unit is used to adjust the position of the thin film so that it is located at the focal plane of the lens group to ensure that the annular light spot is focused on the sample surface and to move the tip thermocouple so that the tip is precisely positioned at the center point of the thin film sample. The preamplifier is used to collect the electrical signal obtained by the periodic temperature change caused by the ring-shaped light spot, and amplify it to obtain the amplified signal. A lock-in amplifier is used to extract the temperature amplitude and phase of the amplified signal from noise using lock-in technology, thereby obtaining temperature response data.

[0033] In some embodiments, a light-blocking plate is placed at the center of the lens to block part of the laser beam from passing through, ensuring that the laser forms a precise annular heating area on the sample surface. A preamplifier is placed between the tip thermocouple and the lock-in amplifier to amplify the weak voltage signal collected by the tip thermocouple and transmit it to the lock-in amplifier to extract the temperature amplitude and phase of the signal.

[0034] It should be noted that the conical lens A is placed in the optical path between the laser beam expander and the lens to form a ring-shaped light spot; the conical lens B is positioned between the lens and the thin film sample; the conical surface of the conical lens A faces the laser beam expander, and the conical surface of the conical lens B faces the focusing lens. The combination of the two conical lenses and the lens can flexibly adjust the laser light spot to a ring shape.

[0035] It should be further noted that if the sample is a conductive thin film, the needle shaft of the thermocouple tip must be insulated, exposing only the tip temperature measuring point to avoid the thermocouple forming an electrical path with the sample, which would interfere with the acquisition of the temperature signal. A ring laser is used to provide a more uniform heat distribution; the center of the ring laser is directly opposite the geometric center of the thin film sample. Place the thin film sample and the thermocouple tip on the sample stage, adjusting the position of the thin film sample so that it is aligned with the focal plane of the lens, allowing the subsequent ring laser to focus on the sample surface; move the thermocouple tip so that its tip is precisely positioned at the center point of the thin film sample.

[0036] The thermal diffusivity calculation module is used to receive and store the temperature response data output by the signal acquisition module, and then process it to obtain the thermal diffusivity value.

[0037] Preferably, it includes: The storage unit is used to receive and store temperature response data, and to correct and optimize the phase-locked temperature response data in combination with initial parameters to obtain optimized data. The calculation unit is used to import the optimized data and initial parameters into the thermal conduction model for error comparison, iteratively update the thermal diffusivity of the thin film, and finally obtain the thermal diffusivity of the thin film sample. One end of the calculation unit is connected to the signal generation module to control signal generation, and the other end is connected to the storage unit to perform rapid analysis and calculation on the optimized data.

[0038] During the calculation, the laser switch is first turned on. The emitted Gaussian laser is modulated by an acousto-optic modulator and then passed sequentially through a laser beam expander, a liquid crystal spatial light modulator, a conical lens A, a light-blocking plate, a lens, and a conical lens B to be shaped into a variable ring-shaped light spot to heat the surface of the thin film sample. A needle-tip thermocouple collects a weak electrical signal of the temperature at the center point of the sample. After the signal is amplified by a preamplifier, a lock-in amplifier extracts the temperature amplitude and phase at the radius of the heat source. The parameters of the liquid crystal spatial light modulator are changed to adjust the radius of the ring laser spot. The above steps are repeated to collect signals under different heat source radii and transmit them to the computing unit. The calculation unit sets the parameters of the signal generator and outputs a cosine electrical signal, which is amplified by the driver of the acousto-optic modulator to drive the acousto-optic modulator. The data is processed to fit the temperature amplitude and phase curves as a function of the heat source radius. The variable radius heat conduction model is called, the initial value of the thin film thermal diffusivity and fixed thermophysical parameters are input, and the corresponding simulated signal is output. The experimental signal and the simulated signal are compared, and the thermal diffusivity of the material is calculated using an AI algorithm.

[0039] Assuming an initial value for the thermal diffusivity of the thin film sample, the laser heating frequency and the radius of the annular heat source are input into the calculation unit. The AI ​​algorithm built into the calculation unit first optimizes the original data. The optimized data is then substituted into the variable radius heat conduction model to calculate the simulated curves of amplitude and phase changes with the radius of the heat source. The difference between the simulated curve and the experimental fitted curve is compared. If the difference is less than a set threshold, the assumed initial value of the thermal diffusivity is the measured thermal diffusivity of the thin film sample. If the difference is greater than the set threshold, the AI ​​algorithm iteratively adjusts the assumed value of the thermal diffusivity and re-substitutes it into the model for calculation until the difference is less than the threshold, at which point the optimal thermal diffusivity of the thin film sample can be output.

[0040] The temperature change at the center point of the thin film sample is as follows: ; in, t Laser heating time, r 1 represents the radius of the annular laser. T 1 represents r = r 1 temperature amplitude, ω Let ω be the angular velocity, and its expression is: ω =2π f , f For frequency; I 0( kr () is a zeroth-order modified Bessel function of the first kind. k It is a complex parameter, expressed as: k =( iω / α ) 1 / 2 , i The imaginary unit; α For thermal diffusivity, the formula is: α=λ / ρc p , λ For the thermal conductivity of the material, ρ For material density, c p arg is the specific heat capacity; I 0( kr 1) ForI 0 ( kr 1) The argument of the complex number is the angle between the complex number and the positive direction of the real axis in the complex plane.

[0041] Furthermore, the amplitude change of the temperature response at the center point of the thin film sample is as follows: ; in, A Indicates the amplitude.

[0042] Furthermore, the phase change of the temperature response at the center point of the thin film sample is as follows: ; in, φ For phase.

[0043] In some embodiments, the computing unit has a built-in thermal conduction model, inputs the thermal property parameters of the thin film material and the parameters of the laser heat source, combines the temperature amplitude and phase extracted by the lock-in amplifier, and uses an AI inversion algorithm to obtain the in-plane thermal diffusivity of the thin film sample. At the same time, it can correct the contact thermal resistance and boundary effects between the probe and the sample, and improve the signal-to-noise ratio.

[0044] The specific derivation process is as follows: Since the thickness of the thin film sample is much smaller than its lateral dimension, it can be approximated as a two-dimensional structure; In polar coordinates, for isotropic materials, the temperature distribution is independent of the polar angle, so it can be assumed to be a one-dimensional problem. Therefore, the one-dimensional unsteady heat conduction differential equation can be obtained as follows: Due to temperature T Only r For ease of calculation, the above expression can be represented as: Assume the temperature solution is a complex function, and let the solution take the form: Wherein, Φ( r ) is a complex amplitude function (only related to radial) r related), ω Let ω be the angular velocity, and its expression is: ω =2π f , f For frequency, i It is the imaginary unit.

[0045] Substituting the temperature solution into the heat conduction differential equation: Cancel both sides of the equation eiωt The radial equation is obtained as follows: make k =( iω / α ) 1 / 2 ,in, α For thermal diffusivity, the formula is: α=λ / ρc p , λ For the thermal conductivity of the material, ρ For material density, c p Specific heat capacity.

[0046] Will k Substituting into the radial equation and simplifying, we get: Variable substitution, let x = kr， but: The standard form of the zeroth-order modified Bessel equation is known to be: It conforms to the standard form of the zeroth-order modified Bessel equation, and the general solution is: in, I 0( kr ) is a first-order zero-order modified Bessel function ( r → converges at 0. I 0(0)=1); K 0( kr ) is the second kind of zeroth-order modified Bessel function ( r → When the value is 0, it diverges and is discarded, hence B=0).

[0047] Therefore, the temperature solution is: r = r 1 represents the outer boundary, and its boundary conditions are as follows: in, T 1 represents r = r Temperature amplitude at point 1.

[0048] Substituting the boundary conditions, we get: Therefore, the final temperature solution is: The actual temperature is either the real or imaginary part of the complex temperature. Ignoring the imaginary part and taking the real part, the final temperature distribution is: Where, arg I 0( kr )for I 0 ( kr The argument of a complex number is the angle between the complex number and the positive direction of the real axis in the complex plane.

[0049] Will r Substituting 0 into the equation yields the temperature change at the center point of the thin film sample: ; The amplitude change of the temperature response at the center point of the thin film sample is as follows: ; in, A Indicates the amplitude.

[0050] The phase change of the temperature response at the center point of the thin film sample is as follows: ; in, φ For phase.

[0051] As can be seen from the above formula, the temperature change at the center point of the thin film sample is related to the laser frequency. f Radius of heat source r 1 and thermal diffusivity α Regarding, at a fixed laser frequency f Under these conditions, the temperature amplitude and phase at the center point of the thin film sample vary with the radius of the heat source. r The change of 1; compared with single-frequency measurement results, the present invention can reduce measurement noise and uncertainty to obtain more accurate results. The curves of temperature amplitude versus heat source radius and phase versus heat source radius under different thermal diffusivity are shown below. Figure 2 As shown.

[0052] Assuming an initial value for the thermal diffusivity of the thin film sample, the sample density and specific heat capacity, laser heating frequency, and radius of the annular heat source are input into the computer. The AI ​​algorithm built into the computing unit first optimizes the original data. The optimized data is then substituted into a variable radius heat conduction model to calculate the simulated curves of amplitude and phase changes with frequency. The difference between the simulated curve and the experimental fitted curve is compared. If the difference is less than a set threshold, the assumed initial value of the thermal diffusivity is the measured thermal diffusivity of the thin film sample. If the difference is greater than the set threshold, the AI ​​algorithm iteratively adjusts the assumed value of the thermal diffusivity and re-substitutes it into the model for calculation until the difference is less than the threshold, at which point the optimal thermal diffusivity of the thin film sample can be output.

[0053] Compared with the prior art, the beneficial effects of the present invention include: This invention enhances the non-destructive nature and high signal-to-noise ratio of the temperature measurement process, solves the problems of complex pretreatment steps, high measurement difficulty, and excessively long measurement time for the thermal transport properties of short thin films, and achieves rapid and accurate measurement capability of the thermal diffusivity of conductive materials, while also being compatible with the measurement of insulating and conductive materials.

[0054] The above is an introduction to the method embodiments. The following system embodiments will further illustrate the solution described in this application.

[0055] Figure 3 This is a flowchart illustrating a method for measuring the thermal diffusivity of a thin film based on a variable-radius ring laser thermal source, according to an exemplary embodiment. This method is used in a thin film thermal diffusivity measurement system based on a variable-radius ring laser thermal source. (Refer to...) Figure 3 The method includes:

[0056] The electronic cosine signal is converted into an amplified electrical signal that drives the acousto-optic modulator; Modulation of a Gaussian laser beam into a ring laser beam yields an expanded beam; The ring laser spot is dynamically and continuously programmed with phase modulation. The programmable phase modulation includes non-contact and non-mechanical dynamic adjustment and real-time adjustment of the center position of the heat source through a liquid crystal spatial light modulator to obtain the heating area corresponding to the ring laser spot. Collect temperature response data of the heating area; The system receives and stores the temperature response data output by the signal acquisition module, and then processes it to obtain the thermal diffusivity value.

[0057] A thin film thermal diffusivity measurement device based on a variable radius ring laser thermal source, the thin film thermal diffusivity measurement device based on a variable radius ring laser thermal source includes: a processor; a memory, the memory storing computer-readable instructions, which, when executed by the processor, implement the method described in any one of the above-described methods for measuring the thermal diffusivity of a thin film based on a variable radius ring laser thermal source.

[0058] A computer-readable storage medium, characterized in that the computer-readable storage medium stores program code, the program code being invoked by a processor to execute the method as described in any one of claims 1 to 7.

[0059] Figure 4 This is a schematic diagram of a thin film thermal diffusivity measurement device based on a variable radius annular laser heat source provided in an embodiment of the present invention, as shown below. Figure 4 As shown, the thin film thermal diffusivity measurement device based on a variable radius annular laser thermal source may include the above-mentioned... Figure 1The illustrated thin-film thermal diffusivity measurement system is based on a variable-radius ring laser thermal source. Optionally, the thin-film thermal diffusivity measurement device 410 based on the variable-radius ring laser thermal source may include a first processor 2001.

[0060] Optionally, the thin film thermal diffusivity measurement device 410 based on a variable radius annular laser thermal source may also include a memory 2002 and a transceiver 2003.

[0061] The first processor 2001, memory 2002, and transceiver 2003 can be connected via a communication bus.

[0062] The following is combined Figure 4 The components of the thin film thermal diffusivity measurement device 410 based on a variable radius annular laser heat source are described in detail below: The first processor 2001 is the control center of the thin film thermal diffusivity measurement device 410 based on a variable radius ring laser heat source. It can be a single processor or a collective term for multiple processing elements. For example, the first processor 2001 can be one or more central processing units (CPUs), application-specific integrated circuits (ASICs), or one or more integrated circuits configured to implement embodiments of the present invention, such as one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs).

[0063] Optionally, the first processor 2001 can perform various functions of the thin film thermal diffusivity measurement device 410 based on a variable radius ring laser thermal source by running or executing software programs stored in the memory 2002 and calling data stored in the memory 2002.

[0064] In a specific implementation, as one example, the first processor 2001 may include one or more CPUs, for example... Figure 4 CPU0 and CPU1 are shown in the diagram.

[0065] In a specific implementation, as one example, the thin film thermal diffusivity measurement device 410 based on a variable radius annular laser heat source may also include multiple processors, for example... Figure 4The first processor 2001 and the second processor 2004 are shown in the diagram. Each of these processors can be a single-core processor or a multi-core processor. Here, a processor can refer to one or more devices, circuits, and / or processing cores used to process data (such as computer program instructions).

[0066] The memory 2002 is used to store the software program that executes the present invention, and is controlled by the first processor 2001 to execute it. The specific implementation method can be referred to the above method embodiment, and will not be repeated here.

[0067] Optionally, the memory 2002 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. The memory 2002 may be integrated with the first processor 2001 or may exist independently, and may be connected via the interface circuit of the thin-film thermal diffusivity measurement device 410 based on a variable radius ring laser heat source. Figure 4 (Not shown in the image) is coupled to the first processor 2001, and this embodiment of the invention does not specifically limit this.

[0068] The transceiver 2003 is used to communicate with network devices or with terminal devices.

[0069] Alternatively, transceiver 2003 may include a receiver and a transmitter. Figure 4 (Not shown separately). The receiver is used to implement the receiving function, and the transmitter is used to implement the transmitting function.

[0070] Optionally, the transceiver 2003 can be integrated with the first processor 2001 or exist independently, and can be connected to the interface circuit of the thin film thermal diffusivity measurement device 410 based on a variable radius ring laser thermal source. Figure 4(Not shown in the image) is coupled to the first processor 2001, and this embodiment of the invention does not specifically limit this.

[0071] It should be noted that, Figure 4 The structure of the thin film thermal diffusivity measurement device 410 based on a variable radius annular laser heat source shown in the figure does not constitute a limitation on the router. Actual knowledge structure identification devices may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0072] Furthermore, the technical effect of the thin film thermal diffusivity measurement device 410 based on a variable radius ring laser heat source can be referred to the technical effect of the thin film thermal diffusivity measurement method based on a variable radius ring laser heat source described in the above method embodiments, and will not be repeated here.

[0073] It should be understood that the first processor 2001 in the embodiments of the present invention may be a central processing unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0074] It should also be understood that the memory in the embodiments of the present invention can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDR SDRAM), enhanced synchronous DRAM (ESDRAM), synchronous linked DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0075] The above embodiments can be implemented, in whole or in part, by software, hardware (such as circuits), firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0076] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0077] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0078] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0079] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0080] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0081] In the several embodiments provided by this invention, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0082] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0083] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0084] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0085] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A thin film thermal diffusivity measurement system based on a variable radius annular laser thermal source, characterized in that, The system includes: The signal generation module is used to convert electronic cosine signals into amplified electrical signals that drive the acousto-optic modulator; The modulation module is used to modulate the Gaussian laser beam into a ring laser spot, thereby obtaining the expanded beam. The dynamic adjustment module is used to dynamically and continuously programmably modulate the phase of the ring laser spot. The programmable phase modulation includes non-contact and non-mechanical dynamic adjustment and real-time adjustment of the center position of the heat source through a liquid crystal spatial light modulator to obtain the heating area corresponding to the ring spot. The signal acquisition module is used to collect temperature response data of the heating area; The thermal diffusivity calculation module is used to receive and store the temperature response data output by the signal acquisition module, and then process it to obtain the thermal diffusivity value.

2. The thin film thermal diffusivity measurement system based on a variable radius annular laser heat source according to claim 1, characterized in that, The signal generation module is used to convert the electronic cosine signal into an amplified electrical signal that drives the acousto-optic modulator, including: A signal generator is used to generate cosine electrical signals. The driver of the acousto-optic modulator is used to amplify the cosine electrical signal to obtain an amplified electrical signal.

3. The thin film thermal diffusivity measurement system based on a variable radius annular laser heat source according to claim 1, characterized in that, The modulation module is used to modulate the Gaussian laser beam into a ring laser spot to obtain an expanded beam, including: Lasers are used to generate Gaussian beams; An acousto-optic modulator is used to modulate a Gaussian beam according to an amplified electrical signal to obtain a modulated beam. A laser beam expander is used to amplify a modulated light beam to obtain an expanded beam.

4. The thin film thermal diffusivity measurement system based on a variable radius annular laser heat source according to claim 1, characterized in that, The dynamic adjustment module is used to dynamically and continuously programmably modulate the phase of the annular laser spot. The programmable phase modulation includes non-contact and non-mechanical dynamic adjustment via a liquid crystal spatial light modulator and real-time adjustment of the heat source center position to obtain the heating area corresponding to the annular laser spot, including: A liquid crystal spatial light modulator is used to perform programmable phase modulation on the expanded beam to control the radius of the annular spot and adjust the center position of the heat source in real time to obtain the encoded beam. The programmable phase modulation includes non-contact adjustment, non-mechanical dynamic adjustment and real-time heat source center position adjustment. The lens group, comprising a combination of a conical lens A, a light-blocking plate, a focusing lens, and a conical lens B, is used to shape the encoded beam into a ring-shaped spot with a variable radius. The light-blocking plate is used to block part of the laser beam from passing through, ensuring that the laser forms a precise ring-shaped heating area on the sample surface.

5. The thin film thermal diffusivity measurement system based on a variable radius annular laser heat source according to claim 4, characterized in that, The liquid crystal spatial light modulator is used to perform programmable phase modulation on the expanded beam to control the radius of the annular spot and adjust the center position of the heat source in real time to obtain the encoded beam. The programmable phase modulation includes non-contact adjustment, non-mechanical dynamic adjustment, and real-time heat source center position adjustment, including: The phase loop diameter is updated in real time by changing the parameters of the phase function; The phase distribution that conforms to the phase ring diameter constraint is converted into a ring beam with a variable radius by using conical lens A, thereby controlling the radius of the ring beam. By adding a translation term to the phase function, the position of the heat source center is adjusted, the radius of the annular spot is controlled, and the encoded beam is obtained.

6. The thin film thermal diffusivity measurement system based on a variable radius annular laser heat source according to claim 1, characterized in that, The signal acquisition module is used to acquire temperature response data of the heating area, including: The sample unit includes a thin film sample, a tip thermocouple, and a sample stage, which are used to place the thin film sample and the tip thermocouple on the sample stage respectively; The adjustment unit is used to adjust the position of the thin film so that it is located at the focal plane of the lens group to ensure that the annular light spot is focused on the sample surface and to move the tip thermocouple so that the tip is precisely positioned at the center point of the thin film sample. The preamplifier is used to collect the electrical signal obtained by the periodic temperature change caused by the ring-shaped light spot, and amplify it to obtain the amplified signal. A lock-in amplifier is used to extract the temperature amplitude and phase of the amplified signal from noise using lock-in technology, thereby obtaining temperature response data.

7. The thin film thermal diffusivity measurement system based on a variable radius annular laser heat source according to claim 1, characterized in that, The thermal diffusivity calculation module is used to receive and store the temperature response data output by the signal acquisition module, and process it to obtain the thermal diffusivity value, including: The storage unit is used to receive and store temperature response data, and to correct and optimize the phase-locked temperature response data in combination with initial parameters to obtain optimized data. The calculation unit is used to import the optimized data and initial parameters into the thermal conduction model for error comparison, iteratively update the thermal diffusivity of the thin film, and finally obtain the thermal diffusivity of the thin film sample. One end of the calculation unit is connected to the signal generation module to control signal generation, and the other end is connected to the storage unit to perform rapid analysis and calculation on the optimized data.

8. A method for measuring the thermal diffusivity of thin films based on a variable-radius ring laser heat source, wherein the method is used to implement the thin film thermal diffusivity measurement system based on a variable-radius ring laser heat source as described in any one of claims 1-7, characterized in that, The method includes: The electronic cosine signal is converted into an amplified electrical signal that drives the acousto-optic modulator; Modulation of a Gaussian laser beam into a ring laser beam yields an expanded beam; The ring laser spot is dynamically and continuously programmed with phase modulation. The programmable phase modulation includes non-contact and non-mechanical dynamic adjustment and real-time adjustment of the center position of the heat source through a liquid crystal spatial light modulator to obtain the heating area corresponding to the ring laser spot. Collect temperature response data of the heating area; The system receives and stores the temperature response data output by the signal acquisition module, and then processes it to obtain the thermal diffusivity value.

9. A thin film thermal diffusivity measurement device based on a variable radius annular laser heat source, characterized in that, The thin film thermal diffusivity measurement processor based on a variable radius annular laser heat source; a memory storing computer-readable instructions, which, when executed by the processor, implement the system as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium contains program code that can be invoked by a processor to execute the system as described in any one of claims 1 to 7.

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