A testing device and testing method for the thermal expansion amount of a solid material

Abstract

This invention discloses a testing device and method for the thermal expansion of solid materials, belonging to the field of instrumentation in physics. The device mainly includes a vacuum chamber, a vacuum generation module, an air drying module, a mechanical refrigeration module, a heat insulation and radiation shielding layer, a laser interferometer, a super-stable support and adjustment module, a temperature measurement and control module, a sample stage, and a sample imaging module. The air drying module reduces the moisture concentration in the vacuum chamber to a predetermined level through the circulation and replacement of drying gas, preventing frost formation during sample heat treatment. The sample imaging module measures the displacement and angular offset of the cold head and sample stage after thermal deformation. The super-stable support and adjustment module actively adjusts the displacement and angle of the laser interferometer, reducing or even eliminating Abbe error. The temperature measurement and control module enables high-precision temperature control of the laser interferometer and the super-stable support structure, reducing baseline drift of the laser interferometer with temperature changes.

Description

Technical Field

[0001] This invention belongs to the field of instruments in physics, specifically relating to a device and method for testing the thermal expansion of solid materials. Background Technology

[0002] Thermal expansion is a macroscopic geometric effect of temperature change in an object. As an intrinsic parameter of the dimensional stability of solid materials, the coefficient of thermal expansion provides important design assurance for the structural safety and high reliability of applications such as spacecraft, functional and structural materials, and electronic component packaging under complex thermal environments.

[0003] Traditional contact-based methods for measuring the coefficient of thermal expansion and thermo-mechanical coupling deformation of solid materials, such as the push-bar method and strain gauge method, have limited coverage of operating temperatures. This results in insufficient technical advantages for traditional contact testing methods in terms of measurement accuracy, cost-effectiveness, and operating temperature range. For example, the commercial push-bar testing equipment (DIL402) from NETZSCH (Germany) has an effective operating temperature range of 130 K to 800 K and a thermal expansion coefficient measurement uncertainty of 5 × 10⁻⁶. -7 The limitations of the laser interferometer, which cannot cover extremely low operating temperatures (<70K) and has low testing uncertainty, restrict the research and application of ultra-stable structural materials and functional materials. Laser interferometers, with their advantages of non-contact and nanometer-level measurement uncertainty, have become important measuring instruments for high-precision measurement of the thermal expansion of solid materials. However, in the process of testing the thermal expansion of solid materials over a wide temperature range with high precision, laser interferometry requires high-precision temperature control of the laser interferometer and the ultra-stable support structure. The temperature change during the test should be less than 200mK to control the baseline drift of the laser interferometer due to temperature changes and the measurement system error caused by the ultra-stable support structure. Furthermore, it is necessary to acquire in real time the offset of the measured axis caused by the thermal deformation of the solid material and the heat-treated support device to reduce the Abbe error caused by the angular deviation between the measured axis and the laser interferometer's measurement optical path.

[0004] In cryogenic engineering, the main cooling methods for solid materials include cryogenic gas immersion cooling and mechanical conduction cooling. For cryogenic gas immersion cooling, the laser interferometer must be placed outside the cryogenic container. The laser interferometer's optical signal passes through the optical window of the cryogenic container to measure the thermal expansion of the solid material. The thermal deformation of the optical window due to the temperature difference between the inside and outside of the cryogenic container, as well as gas turbulence within the container, severely affect the measurement accuracy. For mechanical conduction cooling, the cold head of the compressor heats the solid material on the sample stage inside the vacuum chamber through conduction cooling. The laser interferometer can be placed inside the vacuum chamber, avoiding the influence of thermal deformation of the optical window and gas turbulence on the measurement, resulting in higher engineering reliability.

[0005] Regarding the 1997 report by the National Institute of Metrology of Japan on measuring the coefficient of thermal expansion of metallic copper in the temperature range of 20 K to 300 K using laser interferometry, the solid material was used as a sample and held in parallel by two ultra-smooth optical planes on a spring clamp. During the low-temperature test, thermal deformation of the spring clamp caused changes in the parallelism of the two ultra-smooth optical planes, leading to Abbe error and affecting the accuracy of the thermal expansion measurement. The relevant experimental data and conclusions cannot fully demonstrate the method's ability to test ultra-stable structural materials and ultra-low expansion functional materials.

[0006] Regarding the 2016 report by the German Federal Institute for Technical Physics, the Twyman-Green laser interferometer achieved the measurement of the thermal expansion coefficient of single-crystal silicon in the temperature range of 7 K to 300 K. The thermal deformation of the optical window due to the temperature difference between the inside and outside of the cryogenic container and the gas turbulence inside the cryogenic container can affect the measurement results. In addition, the Twyman-Green laser interferometer has extremely high requirements for the parallelism and surface roughness of the two cross sections of the solid material, and the number of alternative solid materials that can be tested is very limited, mainly including quartz, silicon, sapphire and copper.

[0007] Regarding the mechanical conduction cooling process for solid materials: After the vacuum chamber is closed, mechanical and molecular pumps evacuate the chamber. When the pressure sensor readings show that the pressure inside the vacuum chamber is below 100 Pa or even lower, the refrigerator is activated to transfer heat to the solid material and cool it to the target operating temperature. It is worth noting that when the pressure inside the vacuum chamber decreases, the saturated vapor pressure of water in the air also decreases. For example, at room temperature (293.15 K) and a relative humidity of 50%, the saturated vapor pressure of water is 3168 Pa. Without the technical treatment of circulating and drying the gas inside the vacuum chamber before activating the refrigerator to cool the solid material, frost formation will occur on the sample stage and the surface of the solid material sample during the heat treatment process (cooling and reheating). This severely affects the reflected light signal of the laser interferometer, leading to deviations in the measurement of the thermal expansion of the solid material.

[0008] When the cold head of the compressor conducts heat to the solid material, the thermal deformation of the cold head, sample stage, and solid material can cause a deviation in parallelism between the test optical path of the laser interferometer and the measured axis of the solid material, resulting in Abbe error in the measurement of the thermal expansion of the solid material. If the deviation in parallelism between the test optical path of the laser interferometer and the measured axis of the solid material is too large, it may even cause the loss of the reflected light signal of the laser interferometer, making it impossible to measure the thermal expansion of the solid material.

[0009] Domestic and international research on ultra-low temperature ultra-stable structures (average thermal expansion coefficient <1×10⁻⁶) -6 There are few reports on testing techniques, equipment, and results for the thermal expansion properties of functional materials (e.g., K-type materials).

[0010] In the future, my country's deep space exploration will face the challenge of a complex thermal environment, which will place higher technical requirements on the service temperature range, structural safety, and reliability of spacecraft, functional materials and structures, and electronic component packaging. Summary of the Invention

[0011] This invention proposes a testing device and method for the thermal expansion of solid materials, which can measure the thermal expansion of solid materials in the temperature range of 4.2 K to 400 K.

[0012] The main technical problems solved by this invention are: (1) During the process of mechanically conducting cooling of solid materials, the decrease in air pressure in the vacuum chamber leads to the precipitation of air water, resulting in frost formation on the sample stage and sample surface. (2) During the process of measuring the thermal expansion of the sample with a laser interferometer, the thermal deformation of the cold head, sample stage, and sample causes the deviation of the parallelism between the test optical path of the laser interferometer and the measured axis of the sample, resulting in Abbe error. (3) During the process of measuring the thermal expansion of the sample with a laser interferometer, the measurement error introduced by the temperature change of the laser interferometer and the ultra-stable support structure.

[0013] To solve the above technical problems, the present invention provides a device for testing the thermal expansion of solid materials, which mainly includes a vacuum chamber, a vacuum generation module, an air drying module, a mechanical refrigeration module, a heat insulation and radiation protection layer, a laser interferometer, an ultra-stable support and adjustment module, a temperature measurement and control module, a sample stage, and a sample imaging module.

[0014] The vacuum cavity is equipped with an optical window;

[0015] The vacuum generation module is connected to the mechanical interface of the vacuum chamber and is used to generate a vacuum environment inside the vacuum chamber.

[0016] The air drying module includes a high-purity gas cylinder, a pressure reducing valve, an inlet and outlet gas path, a vaporizer, a ball valve or a one-way valve, a pressure sensor, and a moisture concentration sensor. High-purity gas is introduced and exhausted through the inlet and outlet gas paths. The vaporizer is connected to the high-purity gas inlet gas path, and the high-purity gas is heated by the vaporizer before being introduced into the vacuum chamber. The ball valve or one-way valve controls the inlet and outlet gas flow. The pressure sensor and moisture concentration sensor detect the pressure and moisture content within the vacuum chamber, respectively, to control the inlet and outlet valves.

[0017] The mechanical refrigeration module refrigerates the sample stage;

[0018] The heat insulation and radiation protection layer encloses the ultra-stable support and adjustment module and the mechanical refrigeration module within the vacuum cavity.

[0019] The ultra-stable support and adjustment module includes a support mechanism made of ultra-low expansion material, an electric displacement and angle adjustment mechanism, and a laser interferometer is installed on the ultra-stable support and adjustment module.

[0020] The sample imaging module monitors the displacement and angular offset changes of the sample's measured axis. The ultra-stable support and adjustment module actively compensates for the displacement and angle of the laser interferometer's measuring optical path based on the displacement and angular offset changes of the measured axis, ensuring that the measured axis is parallel to the measuring optical path.

[0021] The temperature measurement and control module measures and controls the temperature of the sample, sample stage, laser interferometer, and mechanical cooling module.

[0022] The heat insulation and radiation protection layer comprises multiple alternating layers of thermal insulation material and metal film material. The thermal insulation material is polyimide foam, glass fiber or carbon fiber woven material; the metal film material is aluminum film, gold film, copper film, or metal-plated polyimide film.

[0023] The temperature measurement and control module includes a temperature controller, a temperature sensor, wires, and a thermal protection mechanism. The temperature controller has four channels: one channel measures the temperature of the sample, one channel measures the temperature of the sample stage, one channel measures the temperature of the laser interferometer, and one channel measures the temperature of the mechanical cooling module's components inside the vacuum chamber.

[0024] The sample imaging module includes an optical camera, a collimating light source, a beam splitter, and an illumination source. The parallel narrow beam emitted by the collimating light source illuminates the sample after passing through the beam splitter and an optical window. The reflected light from the sample enters the optical camera after passing through the optical window and the beam splitter. The optical camera obtains the displacement and angular offset of the measured axis by analyzing the reflected light from the sample. The illumination source illuminates the sample, and the optical camera obtains a cross-sectional image of the sample by analyzing the reflected light from the sample, thereby obtaining the displacement and angular offset of the measured axis.

[0025] The present invention also provides a method for testing the thermal expansion of solid materials, which is implemented using the above-mentioned apparatus and specifically includes the following steps:

[0026] Step 1: The air drying module continuously fills the vacuum chamber with high-purity nitrogen or helium at room temperature through the air inlet pipe. The gas in the vacuum chamber is automatically discharged through the exhaust pipe under the pressure difference.

[0027] Step 2: Close the ball valve of the exhaust pipe. The air drying module fills the vacuum chamber with room temperature high-purity nitrogen or helium through the air intake pipe. The gas in the vacuum chamber is discharged by the vacuum generation module. When the pressure in the vacuum chamber is lower than 4000Pa, stop the vacuum generation module from pumping out the gas.

[0028] Step 3: Repeat step 2 until the moisture concentration in the vacuum chamber is below 50 ppm, then close the ball valve of the air inlet pipe of the air drying module.

[0029] Step 4: Turn on the vacuum generation module to evacuate the vacuum chamber until the pressure inside the vacuum chamber is below 10. -1 The mechanical cooling module and temperature measurement and control module are activated to control the temperature of the laser interferometer.

[0030] Step 5: After the mechanical cooling module cools the sample on the sample stage, turn off the vacuum generation module and the mechanical cooling module.

[0031] Step 6: Activate the laser interferometer to measure the thermal expansion of the sample on the sample stage; activate the temperature measurement and control module to perform reheating heat treatment on the sample on the sample stage; activate the sample imaging module to monitor the displacement and angular offset of the measured axis of the sample; activate the ultra-stable support and adjustment module to actively adjust the displacement and angle of the laser interferometer; the sample imaging module emits a collimated narrow beam, and the optical camera obtains the displacement and angular offset of the measured axis by analyzing the reflected light spot.

[0032] Step 7: Based on the definition of the coefficient of thermal expansion of solid materials, and combined with the data collected by the laser interferometer and the temperature measurement and control module, obtain the test results of the coefficient of thermal expansion of solid materials.

[0033] The beneficial effects of this invention are as follows:

[0034] This invention proposes an air drying module capable of drying the gas inside a vacuum chamber, eliminating surface frost formation on heat-treated samples and ensuring robust laser interferometer reflected light signals and accurate measurement of the sample's thermal expansion coefficient. The air drying module proposed in this invention is also suitable for eliminating surface frost during optical reflection / transmission angle, reflection / transmittance, and reflection / transmission spectral testing of low-temperature samples inside a vacuum chamber.

[0035] This invention proposes a sample imaging module that enables full visualization of the sample's thermal expansion coefficient testing process and measurement of the displacement and angular offset of the measured axis. Based on the displacement and angular offset of the measured axis obtained by the sample imaging module, the ultra-stable support and adjustment module actively adjusts the displacement and angle of the laser interferometer, reducing or even eliminating Abbe error.

[0036] This invention proposes a temperature measurement and control module, which can achieve high-precision temperature control of the laser interferometer and the ultra-stable support structure, and reduce the baseline drift of the laser interferometer as the temperature changes.

[0037] This invention addresses the phenomenon of vertical thermal shrinkage of the sample stage and cold head during heat treatment. The laser interferometer test optical path and the measured axis of the sample can be parallel to the thermal shrinkage direction of the sample stage and cold head. This test layout of the laser interferometer and the sample can ensure the engineering reliability of the ultra-stable support and adjustment module, while avoiding the impact of inconsistencies in the surface contour of the sample measured at the test position on the measurement accuracy. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the device for testing the thermal expansion of solid materials according to the present invention.

[0039] Figure 2 This is a schematic diagram of the optical path for testing the thermal expansion coefficient of solid materials in Embodiment 1 of the present invention. It mainly includes a vacuum cavity 110, an optical window 111, a laser interferometer 160, an ultra-stable support and adjustment module 170, a temperature measurement and control module 180, a sample stage 190, a sample 191, an optical camera 204, a collimating light source 201, a beam splitter 202, and an illumination light source 203.

[0040] Figure 3 This is a schematic diagram of the optical path for testing the thermal expansion coefficient of solid materials in Embodiment 2 of the present invention. It mainly includes a vacuum cavity 110, an optical window 111, a mechanical cooling module 140, a heat insulation and radiation protection layer 150, a laser interferometer 160, a temperature measurement and control module 180, a sample stage 190, a sample 191, and a heating resistor 192.

[0041] Figure 4 This is a schematic diagram of the optical path for testing the thermal expansion coefficient of solid materials in Embodiment 3 of the present invention.

[0042] Figure 5 This is a schematic diagram comparing air drying and replacement in a vacuum chamber according to an embodiment of the present invention;

[0043] Figure 6 This is a schematic diagram illustrating the temperature change over time in a laser interferometer within a vacuum cavity according to an embodiment of the present invention.

[0044] Figure 7 This is a schematic diagram of the baseline drift of an open laser interferometer in a vacuum cavity according to an embodiment of the present invention.

[0045] Figure 8 The test results of the average thermal expansion coefficient of the quartz rod standard provided in the embodiments of the present invention. Detailed Implementation

[0046] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0047] This invention provides a device for testing the thermal expansion of solid materials, such as... Figure 1The cross-sectional view shown includes a vacuum cavity 110 equipped with an optical window 111, a vacuum generation module 120, an air drying module 130, a mechanical cooling module 140, a heat insulation and radiation protection layer 150, a laser interferometer 160, an ultra-stable support and adjustment module 170, a temperature measurement and control module 180, a sample stage 190, and a sample imaging module 200.

[0048] The vacuum chamber 110 is a metal or metal alloy chamber, which is equipped with an optical window, a fiber optic flange, an electrical interface, and a mechanical interface. The optical window 111 and the fiber optic flange are sealed with metal, and the electrical interface and the mechanical interface are sealed with elastomeric seals.

[0049] The vacuum generation module 120 includes a mechanical pump and a molecular pump, or a combination of a mechanical pump, a molecular pump and a cryogenic pump, which is connected to the mechanical interface of the vacuum chamber 110. The vacuum generation module 120 generates a vacuum environment in the vacuum chamber by pumping air through the pump group.

[0050] The air drying module 130 includes a high-purity nitrogen or helium cylinder, a pressure reducing valve, an air intake / exhaust passage, a vaporizer, a ball valve or a one-way valve, a pressure sensor, and a moisture concentration sensor.

[0051] High-purity gas is introduced and discharged through the intake / exhaust gas path; the vaporizer is connected to the intake gas path of the high-purity gas, and the high-purity gas is heated to room temperature by the vaporizer and then filled into the vacuum chamber 110; a ball valve or a one-way valve controls the intake / exhaust, and a pressure sensor and a moisture concentration sensor detect the pressure and moisture in the vacuum chamber to control the intake / exhaust valve.

[0052] The mechanical refrigeration module 140 includes a GM refrigerator and a chiller. The cold head of the GM refrigerator is sealed in a vacuum chamber with metal to cool the sample stage 190.

[0053] The heat insulation and radiation protection layer 150 comprises multiple alternating layers of thermal insulation material / metal film material. The thermal insulation material can be polyimide foam, glass fiber, and carbon fiber woven material; the metal film material can be aluminum film, gold film, copper film, and metal-plated polyimide film. The heat insulation and radiation protection layer 150 wraps around the outer surfaces of the ultra-stable support and adjustment module 170 and the mechanical cooling module 140 within the vacuum cavity 110, thus isolating the temperatures of each component and preventing them from affecting each other.

[0054] The laser interferometer 160 includes an optical lens, a signal acquisition controller, and host computer software 210.

[0055] The ultra-stable support and adjustment module 170 includes a support mechanism for ultra-low expansion materials and an electric displacement and angle adjustment mechanism, possessing high-precision pitch, yaw, and translation adjustment capabilities. A laser interferometer 160 is mounted on the ultra-stable support and adjustment module 170. During the testing of the thermal expansion of the solid material, the sample imaging module 200 monitors the displacement and angular offset changes of the measured axis of the sample 191. Based on these changes, the ultra-stable support and adjustment module 170 actively compensates for the displacement and angle of the measuring optical path of the laser interferometer 160, ensuring the parallelism between the measured axis and the measuring optical path.

[0056] The temperature measurement and control module 180 includes a temperature controller, a temperature sensor, wires, and a thermal protection mechanism. The temperature controller has four channels: one channel measures the temperature of the sample 191, one channel measures the temperature of the sample stage 190, one channel measures the temperature of the laser interferometer, and one channel measures the temperature of the components of the mechanical cooling module 140 within the vacuum chamber 110. The temperature measurement and control module 180 possesses the temperature control capability of the laser interferometer 160, and the temperature change of the laser interferometer 160 during the thermal expansion test is less than 200 mK.

[0057] The sample stage 190 includes a sample stage with high thermal conductivity and a sample 191.

[0058] The sample imaging module 200 is as follows Figure 2 As shown, the system includes an optical camera 204, a collimating light source 201, a beam splitter 202, and an illumination source 203. A parallel, narrow beam of light emitted from the collimating light source 201 illuminates the sample 191 after passing through the beam splitter 202 and optical window 111. The reflected light from the sample 191 passes through the optical window 111 and beam splitter 202 before entering the optical camera 204. The optical camera 204 analyzes the reflected light from the sample 191 to obtain the displacement and angular offset of the measured axis. The illumination source 203 illuminates the sample 191, and the optical camera 204 acquires a cross-sectional image of the sample 191 through the reflected light, and can also analyze the displacement and angular offset of the measured axis.

[0059] The present invention also provides a method for testing the thermal expansion of solid materials by using the above-described apparatus, the specific steps of which are as follows:

[0060] like Figure 1 As shown, after the vacuum generation module 120, air drying module 130, mechanical refrigeration module 140, laser interferometer 160, temperature measurement and control module 180, and sample imaging module 200 of the present invention are initialized normally, the vacuum chamber 110 is closed.

[0061] The test procedure for the thermal expansion of solid materials is as follows:

[0062] Step 1: The air drying module 130 continuously fills the vacuum chamber 110 with room temperature high-purity nitrogen or helium through the air inlet pipe. The gas in the vacuum chamber 110 is automatically discharged through the exhaust pipe under the pressure difference.

[0063] Step 2: Close the ball valve of the exhaust pipe. The air drying module 130 fills the vacuum chamber 110 with room temperature high-purity nitrogen or helium through the air inlet pipe (the pressure of the nitrogen or helium filling is not less than 2 atmospheres). The gas in the vacuum chamber 110 is discharged through the vacuum generation module 120. When the pressure in the vacuum chamber 110 is lower than 4000Pa, stop the vacuum generation module 120 from pumping.

[0064] Step 3: Repeat step 2 until the moisture concentration in the vacuum chamber 110 is below 50 ppm, then close the ball valve of the air inlet pipe of the air drying module 130.

[0065] Step 4: Activate the vacuum generation module 120 to evacuate the vacuum chamber 110 until the pressure inside the vacuum chamber is below 10. -3 The mechanical cooling module 140 and the temperature measurement and control module 180 are activated to control the temperature of the laser interferometer 160.

[0066] Step 5: After the mechanical cooling module 140 cools the sample on the sample stage 190 to 4.2K, the vacuum generation module 120 and the mechanical cooling module 140 are turned off.

[0067] Step Six: The laser interferometer 160 is turned on to measure the thermal expansion of the sample on the sample stage 190. The temperature measurement and control module 180 is turned on to perform a reheating heat treatment on the sample on the sample stage. The sample imaging module 200 is turned on to monitor the displacement and angular offset of the measured axis of the sample. The ultra-stable support and adjustment module 170 actively adjusts the displacement and angle of the laser interferometer. The sample imaging module 200 can actively emit a collimated fine beam. The optical camera obtains the displacement and angular offset of the measured axis by resolving the reflected light spot.

[0068] Step 7: Based on the definition of the coefficient of thermal expansion of solid materials, and combined with the data collected by the laser interferometer 160 and the temperature measurement and control module 180, obtain the test results of the coefficient of thermal expansion of solid materials.

[0069] Figure 2 This is a schematic diagram of the optical path for testing the coefficient of thermal expansion of solid materials in Embodiment 1 of the present invention. The measured axis of the sample 191 on the sample stage 190 is within the cross-section of the vacuum cavity 110. The laser interferometer 160 measures the thermal expansion at both ends of the sample. The temperature measurement and control module 180 controls the temperature of the laser interferometer 160 to reduce the baseline drift of the laser interferometer 160 as the temperature changes. The temperature measurement and control module 180 heats the sample stage 190 to ensure that the sample recovers at a rate of 3K / minute.

[0070] Figure 3 This is a schematic diagram of the optical path for testing the coefficient of thermal expansion of solid materials in Embodiment 2 of the present invention. The sample measurement axis of the sample stage 190 is within the vertical section of the vacuum cavity 110. Two laser interferometers 160 measure the thermal expansion of the sample and the quartz standard, respectively. The temperature measurement and control module 180 controls the temperature of the laser interferometer 160 to reduce the baseline drift of the laser interferometer 160 as the temperature changes. The temperature measurement and control module 180 controls the heating resistor 192 to heat the sample stage 190 to ensure that the sample recovers at a rate of 3K / minute.

[0071] The two laser interferometers 160 in Embodiments 1 and 2 of the present invention can be placed on the same side or both sides of the sample, and can achieve high-precision measurement of the thermal expansion of solid materials.

[0072] Figure 4 This is a schematic diagram of the optical path for testing the coefficient of thermal expansion of solid materials in Embodiment 3 of the present invention. The sample 191 is located in the sample slot of the sample stage 190, and the measured axis of the sample is within the vertical section of the vacuum cavity 110. Four laser interferometers 160 measure the thermal expansion at both ends of the two samples respectively. The temperature measurement and control module 180 controls the temperature of the laser interferometers 160 to reduce the baseline drift of the laser interferometers 160 as the temperature changes. The temperature measurement and control module 180 controls the heating resistor 192 to heat the sample stage 190 to ensure that the sample recovers at a rate of 3K / minute.

[0073] Figure 5 On the left, in the example where no air drying or replacement was performed in the vacuum chamber, surface frost appeared on the sample during the thermal expansion test. Figure 5 On the right is the embodiment of the present invention, in which the air drying module 130 performs air drying and replacement in the vacuum chamber 110, and no surface frost phenomenon occurs during the test of the thermal expansion of the sample.

[0074] like Figure 6 As shown, during the thermal expansion test in the vacuum cavity 110 of this embodiment of the invention, the temperature measurement and control module 180 is turned on to control the temperature of the laser interferometer 160. During the thermal expansion test, the temperature change of the laser interferometer 160 is less than 100mK.

[0075] like Figure 7 As shown, the temperature change of the laser interferometer 160 in this embodiment of the invention is less than 100 mK, and the baseline drift of the laser interferometer 160 is less than 20 nm.

[0076] Figure 8 The present invention discloses test results for the thermal expansion coefficient of quartz rod standard samples from 20 K to 280 K using the device, and the maximum deviation between the test data and the standard sample data is much less than 10. -7 / K, the accuracy of the thermal expansion coefficient test of the device of the present invention is not affected by the temperature of the sample operating conditions.

[0077] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A device for testing the thermal expansion of solid materials, characterized in that, It includes a vacuum chamber (110), a vacuum generation module (120), an air drying module (130), a mechanical refrigeration module (140), a heat insulation and radiation protection layer (150), a laser interferometer (160), an ultra-stable support and adjustment module (170), a temperature measurement and control module (180), a sample stage (190), and a sample imaging module (200). The vacuum cavity (110) is equipped with an optical window (111); The vacuum generation module (120) is connected to the vacuum chamber (110) via a mechanical interface and is used to generate a vacuum environment within the vacuum chamber. The air drying module (130) includes a high-purity gas cylinder, a pressure reducing valve, an inlet and outlet gas path, a vaporizer, a ball valve or a one-way valve, a pressure sensor, and a moisture concentration sensor. The high-purity gas is introduced and discharged through the inlet and outlet gas path. The vaporizer is connected to the inlet gas path of the high-purity gas, and the high-purity gas is heated by the vaporizer and then filled into the vacuum chamber (110). The ball valve or one-way valve controls the opening and closing of the inlet and outlet gas, and the pressure sensor and moisture concentration sensor detect the pressure and moisture in the vacuum chamber, respectively, to control the inlet and outlet valves. The mechanical refrigeration module (140) refrigerates the sample stage; The heat insulation and radiation protection layer (150) encloses the components of the ultra-stable support and adjustment module (170) and the mechanical refrigeration module (140) within the vacuum chamber (110); The ultra-stable support and adjustment module (170) includes a support mechanism made of ultra-low expansion material, an electric displacement and angle adjustment mechanism, and a laser interferometer (160) is installed on the ultra-stable support and adjustment module (170). The sample imaging module (200) monitors the displacement and angular offset of the sample's measured axis. The ultra-stable support and adjustment module (170) actively compensates the displacement and angle of the laser interferometer (160) according to the displacement and angular offset of the measured axis, ensuring that the measured axis is parallel to the measurement optical path. The temperature measurement and control module (180) measures and controls the temperature of the sample, sample stage, laser interferometer, and mechanical cooling module.

2. The apparatus for testing the thermal expansion of a solid material according to claim 1, characterized in that, The heat insulation and radiation protection layer (150) includes multiple alternating layers of thermal insulation material and metal film material. The thermal insulation material is polyimide foam, glass fiber or carbon fiber woven material; the metal film material is aluminum film, gold film, copper film or metal-plated polyimide film.

3. The apparatus for testing the thermal expansion of a solid material according to claim 2, characterized in that, The temperature measurement and control module (180) includes a temperature controller, a temperature sensor, wires and a thermal protection mechanism; the temperature controller has 4 channels to measure the temperature of the sample, the temperature of the sample stage (190), the temperature of the laser interferometer, and the temperature of the components of the mechanical cooling module (140) in the vacuum chamber (110).

4. The device for testing the thermal expansion of a solid material according to claim 3, characterized in that, The sample imaging module (200) includes an optical camera (204), a collimating light source (201), a beam splitter (202), and an illumination source (203). The parallel fine beam emitted by the collimating light source (201) illuminates the sample (191) after passing through the beam splitter (202) and the optical window (111). The reflected light from the sample (191) enters the optical camera (204) after passing through the optical window (111) and the beam splitter (202). The optical camera (204) obtains the displacement and angular offset of the measured axis by analyzing the reflected light from the sample (191). The illumination source (203) illuminates the sample (191), and the optical camera (204) obtains the cross-sectional image of the sample (191) by analyzing the reflected light from the sample (191) and obtains the displacement and angular offset of the measured axis.

5. The apparatus for testing the thermal expansion of a solid material according to claim 4, characterized in that, The test axes of the sample (191) and the quartz standard on the sample stage (190) are in the cross section or vertical section of the vacuum cavity (110), and the laser interferometer (160) measures the thermal expansion of the sample and the quartz standard respectively.

6. The apparatus for testing the thermal expansion of a solid material according to claim 4, characterized in that, The sample (191) is placed in the sample slot of the sample stage (190), and the measured axis of the sample is in the vertical section of the vacuum cavity (110). Four laser interferometers (160) measure the thermal expansion at both ends of the two samples respectively.

7. A method for testing the thermal expansion of a solid material, characterized in that, Based on the testing device for the thermal expansion of solid materials as described in any one of claims 1-6, the specific steps include: Step 1: The air drying module (130) continuously fills the vacuum chamber (110) with room temperature high-purity nitrogen or helium through the air inlet pipe. The gas in the vacuum chamber (110) is automatically discharged through the exhaust pipe under the pressure difference. Step 2: Close the ball valve of the exhaust pipe. The air drying module (130) fills the vacuum chamber (110) with room temperature high-purity nitrogen or helium through the air inlet pipe. The gas in the vacuum chamber (110) is pumped out by the vacuum generation module (120). The pressure in the vacuum chamber (110) is lower than 4000Pa. Stop the pumping of the vacuum generation module (120). Step 3: Repeat step 2 until the moisture concentration in the vacuum chamber (110) is below 50 ppm, then close the ball valve of the air inlet pipe of the air drying module (130); Step 4: Turn on the vacuum generation module (120) to evacuate the vacuum chamber (110), and the gas pressure inside the vacuum chamber is lower than 10. -1 The mechanical cooling module (140) and the temperature measurement and control module (180) are activated to control the temperature of the laser interferometer (160); Step 5: After the mechanical cooling module (140) cools the sample on the sample stage (190), the vacuum generation module (120) and the mechanical cooling module (140) are turned off. Step 6: Turn on the laser interferometer (160) to measure the thermal expansion of the sample on the sample stage (190), turn on the temperature measurement and control module (180) to perform heat treatment on the sample on the sample stage, turn on the sample imaging module (200) to monitor the displacement and angular offset of the measured axis of the sample, and the ultra-stable support and adjustment module (170) actively adjusts the displacement and angle of the laser interferometer; the sample imaging module (200) emits a collimated fine beam, and the optical camera obtains the displacement and angular offset of the measured axis by analyzing the reflected light spot; Step 7: Based on the definition of the coefficient of thermal expansion of solid materials, and combined with the data collected by the laser interferometer (160) and the temperature measurement and control module (180), the test results of the coefficient of thermal expansion of solid materials are obtained.

Images