Electrostriction coefficient measuring device and method based on loyd's mirror interferometry

Abstract

The invention belongs to the technical field of material characteristic measurement, and relates to an electrostriction coefficient measuring device and method based on a loyd's mirror interference method. Voltage is applied to the to-be-measured sample to change the deformation quantity of the to-be-measured sample so as to change the reflection angle of the reflector to the laser, so that interference fringes corresponding to different voltage values are generated on the optical screen; constructing a first relation function of the deformation quantity of the to-be-tested sample and the fringe coordinate variation quantity of the interference fringes based on the Lloyd's mirror interference principle and the triangle similarity principle; constructing a second relation function among the electrostriction coefficient and the voltage value of the to-be-tested sample and the deformation quantity of the to-be-tested sample based on the piezoelectric effect; based on the first relation function and the second relation function, constructing a third relation function of the voltage value and the stripe coordinate variation; and based on the third relation function and the interference fringes corresponding to different voltage values, fitting to obtain a linear correlation coefficient of the voltage values and the fringe coordinate variation, thereby calculating the electrostriction coefficient of the to-be-measured sample.

Description

Technical Field

[0001] The present invention relates to the technical field of material property measurement, and in particular to a device and method for measuring an electrostriction coefficient based on a Loey mirror interferometry method. Background Art

[0002] The electrostrictive coefficient is a physical quantity used to describe the degree of strain produced by a material under the action of an electric field. When a material is in an electric field, the charged particles inside it will be displaced under the action of the electric field force, causing the lattice structure of the material to change, thereby causing the shape and size of the material to change. The electrostrictive coefficient can quantitatively represent the relationship between the electric field strength and the material strain. By measuring the electrostrictive coefficient of a material, we can accurately understand the sensitivity of the material to deformation induced by an electric field, and thus provide a basis for the selection and application of materials in different application scenarios. For example, when manufacturing high-precision sensors, it is necessary to find a material with a stable and moderate electrostrictive coefficient. If the electrostrictive coefficient of the material is too large, it will cause the sensor to be overly sensitive to weak electric field signals and generate noise interference. If the electrostrictive coefficient is too small, it will not be able to effectively sense changes in the electric field, affecting the sensitivity of the sensor.

[0003] The existing technology includes the electrostriction coefficient measurement method based on the capacitance method, the electrostriction coefficient measurement method based on the periodic pressure method and the electrostriction coefficient measurement method based on the vertical loading method. Figure 1 The figure shows a schematic diagram of the electrostrictive coefficient measurement principle based on the capacitance method. This method converts the electrostrictive coefficient strain of the sample into micro-capacitance changes, measures the electrostrictive coefficient by measuring the changes in micro-capacitance, and measures the electrostrictive coefficient and driving force of the material under force load in combination with the driving force of the driving coil. Specifically, it includes an adjustable high voltage source, a fixed base, a three-dimensional micro-displacement stage, high-voltage positive and negative plates, a sample to be measured, an excitation pre-dissuasion, a micro-displacement sensing capacitor and its measurement control circuit. During measurement, the high-voltage power supply loads a strong electric field on the sample to be measured to cause the sample to deform, and the micro-displacement sensing capacitor measures the corresponding micro-displacement. At the same time, a force load is generated by driving the excitation coil to offset the strong electric field, and the electrostrictive coefficient of the sample to be measured is measured. The specific calculation formula is: ,in, is the dielectric constant, is the plate area, 、 are the capacitance values ​​of the sample before and after deformation. Although this method can measure the electrostrictive coefficient of the sample, there is a high output impedance during the measurement process, and the parasitic capacitance between the measurement components will reduce the measurement sensitivity to the sample deformation, affecting the accuracy of the measurement results. Figure 2The figure shows a schematic diagram of the electrostriction coefficient measurement principle based on the periodic pressure method. A piezoelectric transducer connected to a metal rod is placed close to the surface of the sample to be measured. The piezoelectric transducer is connected to the silicon substrate. The piezoelectric transducer converts the step pulse generated by the pulse generator into a longitudinal audio pulse, which is then transmitted to the coupling liquid through the metal rod. The audio pulse generates a mechanical load on the sample to be measured. At the same time, the mechanical deformation of the sample to be measured is converted into an electrical signal and output from the electrode. Assume that the collected charge is , replace the sample to be tested with a reference piezoelectric sheet with a known electrostrictive coefficient, repeat the above operation, and the collected charge is , then the electrostrictive coefficient of the sample to be tested is , is the electrostrictive coefficient of the reference piezoelectric piece; when using this method to measure the electrostrictive coefficient of the sample, it is necessary to perform exactly the same measurement operation on the sample to be tested and the reference piezoelectric piece to ensure the accuracy of the measurement results. However, the sample to be tested and the reference piezoelectric piece have different wettability to the coupling liquid, so it is difficult to meet this requirement. At the same time, when the pulse frequency generated by the pulse generator is lower than the frequency of the free electrons in the diaphragm of the sample to be tested or higher than the fundamental modal frequency, resonance will occur, affecting the measurement results. In addition, the bending effect of the substrate during the measurement process will also affect the accuracy of the measurement results. The electrostrictive measurement method based on the vertical loading method applies a mechanical load F to the upper and lower surfaces of the sample to be tested, thereby generating a certain amount of charge Q on the electrode, and then a standard capacitor with a capacitance value much larger than the capacitance value of the sample to be tested is connected in series with the sample to be tested, and the voltage across the standard capacitor is measured with an electrometer to calculate the electrostrictive coefficient of the sample to be tested. The specific calculation formula is: ,in, is the capacitance value of the standard capacitor, is the voltage across the standard capacitor; during measurement, a mechanical load needs to be applied to the sample to be tested through one or several specific points, resulting in uneven force on the sample to be tested, thus affecting the accuracy of the measurement results.

[0004] The prior art also provides a method for measuring the electrostriction coefficient based on the Michelson interferometer method, which uses optical principles to reflect the deformation of the sample under voltage excitation as changes in interference fringes, such as Figure 3The figure shows the measurement device and principle of this method. M1 and M2 are reflectors, and G is a semi-transparent and semi-reflective beam splitter, which is used to split the light projected by the light source into two beams of equal intensity and project them to M1 and M2 respectively. M1 and M2 reflect the light beams to G1. After reflection or transmission by G1, interference occurs and interference fringes are generated on the receiving screen. By applying a DC voltage at both ends of the polarization direction (direction 2) and perpendicular to the polarization direction (direction 1) of the sample to be tested, the sample to be tested produces deformation in directions 1 and 2. A microscope is used to obtain the interference fringes on the receiving screen based on the sample to be tested before and after deformation. Then, the host computer is used to calculate the electrostriction coefficient of the sample to be tested based on the number of fringes moved in the interference fringes before and after deformation of the sample to be tested. , and its specific calculation formula is: ,in, is the size of the sample to be tested perpendicular to the polarization direction, is the size of the sample in the polarization direction, is the DC voltage applied to both ends of the polarization direction of the sample to be tested, is the deformation of the sample to be tested perpendicular to the polarization direction, It is the number of fringe movements in the interference fringes produced before and after the sample to be tested is deformed.

[0005] By acquiring interference fringes produced by the sample under test under different voltage excitations, the deformation of the sample under test is reflected based on the changes in the interference fringes, thereby calculating its electrostrictive coefficient. This avoids the problem of electrical interference caused by the introduction of electrical components during the measurement process and has high measurement accuracy. However, during measurement, it is necessary to count the number of fringe movements in different interference fringes. Because the human eye has a visual resolution limit for tiny fringe movements when observing interference fringes, it is difficult to accurately measure and count the movement of a small number of fringes, affecting the accuracy of the measurement results. At the same time, according to the above-mentioned electrostrictive coefficient calculation formula, the electrostrictive coefficient is proportional to the number of fringe movements. Therefore, when the number of fringes in the interference fringes is small, the counting error of the number of fringe movements has a greater impact on the measurement result of the electrostrictive coefficient, resulting in a lower accuracy of the final calculated electrostrictive coefficient. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the problem of low measurement accuracy of the electrostrictive coefficient measurement method in the prior art.

[0007] To solve the above technical problems, the present invention provides a method for measuring the electrostriction coefficient based on the Loey mirror interferometry method, comprising: Applying voltage to the sample to be tested to change the deformation of the sample to be tested, so as to change the reflection angle of the reflector to the laser emitted by the light source, thereby generating interference fringes corresponding to different voltage values ​​on the light screen; Based on the Lloyd's mirror interference principle and the triangle similarity principle, a first relationship function is constructed between the deformation of the sample to be tested and the change in the fringe coordinates of the interference fringes; based on the piezoelectric effect, a second relationship function is constructed between the electrostriction coefficient, voltage value, and deformation of the sample to be tested; Based on the first relationship function and the second relationship function, constructing a third relationship function between the voltage value and the stripe coordinate change; Based on the third relationship function and the fringe coordinates of the interference fringes with the maximum or minimum brightness value corresponding to different voltage values, a linear correlation coefficient between the voltage value and the change in the fringe coordinates is obtained by fitting; The electrostriction coefficient of the sample to be measured is calculated based on the linear correlation coefficient, the size of the sample to be measured, the distance between the reflector and the light source, the size of the reflector, and the distance between the light source and the light screen.

[0008] Preferably, the first relationship function is: , in, Indicates the deformation of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the change in the fringe coordinates of the interference fringes.

[0009] Preferably, the second relationship function is: , in, Indicates the electrostrictive coefficient of the sample to be tested; Indicates the deformation of the sample to be tested; Indicates the size of the sample to be tested along the deformation direction; Indicates the size of the sample to be tested in the direction perpendicular to the deformation direction; Indicates the voltage value of the power supply.

[0010] Preferably, the third relationship function is: , in, Indicates the change in the fringe coordinates of the interference fringes; Indicates the electrostrictive coefficient of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the size of the sample to be tested along the deformation direction; Indicates the size of the sample to be tested in the direction perpendicular to the deformation direction; Indicates the voltage value of the power supply.

[0011] Preferably, the linear correlation coefficient between the voltage value and the fringe coordinate change is: , in, Indicates the linear correlation coefficient between the voltage value and the change in the fringe coordinates; Indicates the electrostrictive coefficient of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the size of the sample to be tested along the deformation direction; Indicates the dimension of the sample to be tested in the direction perpendicular to the deformation direction.

[0012] Preferably, the calculation formula of the electrostrictive coefficient of the sample to be tested is: , in, Indicates the electrostrictive coefficient of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the size of the sample to be tested along the deformation direction; Indicates the size of the sample to be tested in the direction perpendicular to the deformation direction; It represents the linear correlation coefficient between the voltage value and the change in the fringe coordinates.

[0013] Preferably, based on the third relationship function and the fringe coordinates of the interference fringes with the maximum or minimum brightness value corresponding to different voltage values, the linear correlation coefficient between the voltage value and the change in the fringe coordinate obtained by fitting includes: Convert the interference fringes corresponding to different voltage values ​​into a fringe coordinate-brightness curve graph corresponding to different voltage values, and obtain the fringe coordinates with the maximum or minimum brightness value in the fringe coordinate-brightness curve graph corresponding to each voltage value; The third relationship function and the fringe coordinates with the maximum or minimum brightness value in the fringe coordinate-brightness curve corresponding to each voltage value are input into the Origin software, and a relationship graph between the voltage value and the fringe coordinate change is obtained by fitting; A linear correlation coefficient between the voltage value and the fringe coordinate variation is obtained based on the voltage value and fringe coordinate variation relationship diagram.

[0014] The present invention also provides an electrostriction coefficient measurement device based on the Lloyds mirror interferometry method, which is used to implement the above-mentioned electrostriction coefficient measurement method based on the Lloyds mirror interferometry method, comprising: a light source for emitting laser light so that the laser light is incident on the reflector at a grazing angle of incidence; A power supply, connected to the sample to be tested, for applying a voltage to the sample to be tested, thereby changing the deformation of the sample to be tested; A support block, located at the same horizontal plane as the sample to be tested; a reflector, placed on the surface of the sample to be tested and the support block, with one end in contact with the sample to be tested and the other end in contact with the support block; used to reflect the laser and output a reflected light beam corresponding to the current voltage value when the voltage value of the power supply changes; a light screen, configured to generate interference fringes based on the interference light of the reflected light beam and the laser, thereby obtaining interference fringes corresponding to different voltage values; An image processing module, connected to a host computer, for collecting and amplifying interference fringes corresponding to the different voltage values, and sending the interference fringes to the host computer; The host computer includes: A first relationship function and a second relationship function construction module are configured to construct a first relationship function between the deformation of the sample to be tested and the change in the fringe coordinates of the interference fringes based on the Lloyd's mirror interference principle and the triangle similarity principle; and to construct a second relationship function between the electrostriction coefficient, voltage value, and deformation of the sample to be tested based on the piezoelectric effect; A third relationship function construction module, configured to construct a third relationship function between the voltage value and the fringe coordinate variation based on the first relationship function and the second relationship function; a linear correlation coefficient acquisition module, configured to obtain, based on the third relationship function and the fringe coordinates of the interference fringes with the maximum or minimum brightness value corresponding to different voltage values, a linear correlation coefficient between the voltage value and the fringe coordinate change; The electrostriction coefficient calculation module is used to calculate the electrostriction coefficient of the sample to be tested based on the linear correlation coefficient, the size of the sample to be tested, the distance between the reflector and the light source, the size of the reflector, and the distance between the light source and the light screen.

[0015] Preferably, it also includes: A support platform, used for placing the sample to be tested and the support block; A plurality of iron frames are used to fix the light source, the light screen and the image processing module respectively.

[0016] Preferably, the size of the contact area between the reflector and the sample to be measured is smaller than the size of the surface of the sample to be measured that contacts the reflector.

[0017] The electrostrictive coefficient measurement method based on the Loey mirror interferometry provided in the present application changes the deformation of the sample to be measured by applying different voltages to the sample to be measured, thereby generating interference fringes corresponding to different voltage values. According to the Loey mirror interference principle and the triangle similarity principle, the deformation of the sample to be measured at different voltage values ​​and the change in the fringe coordinates in the corresponding interference fringes satisfy a linear relationship. Therefore, a first relationship function between the deformation of the sample to be measured and the change in the fringe coordinates of the interference fringes is constructed; according to the linear relationship between the deformation of the sample to be measured and the voltage value, and the linear relationship between the deformation and the electrostrictive coefficient under the piezoelectric effect, a first relationship function between the deformation of the sample to be measured, the voltage value and the electrostrictive coefficient is constructed. The invention relates to a method for calculating the electrostrictive coefficient of the sample to be tested, wherein the first relationship function is substituted into the second relationship function to obtain a third relationship function between the voltage value applied to the sample to be tested and the change in the fringe coordinates. The interference fringes corresponding to different voltage values ​​are substituted into the third relationship function to fit a relationship curve between the voltage value and the change in the fringe coordinates, thereby obtaining a linear correlation coefficient between the voltage value and the change in the fringe coordinates. The electrostrictive coefficient of the sample to be tested is calculated by comprehensively considering the relationship between the voltage value, the change in the fringe coordinates and the electrostrictive coefficient. There is no need to count the number of fringe movements in different interference fringes, thereby avoiding the problem of low electrostrictive coefficient measurement accuracy caused by counting errors, and making the calculated electrostrictive coefficient more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 Schematic diagram of the electrostriction coefficient measurement principle based on the capacitance method provided in this application; Figure 2 Schematic diagram of the electrostriction coefficient measurement principle based on the periodic pressure method provided in this application; Figure 3 Schematic diagram of the electrostriction coefficient measurement principle based on Michelson interferometry provided in this application; Figure 4 Flowchart of the electrostriction coefficient measurement method based on the Loey mirror interferometry provided in this application; Figure 5 Schematic diagram of the interferometry principle of the Loey mirror provided for this application; Figure 6 A schematic diagram of the structure of a sample to be tested provided in this application; Figure 7 A schematic diagram of the axial height increment of the sample to be tested under the action of voltage provided in this application; Figure 8Schematic diagram of the relationship between the deformation of the sample to be measured and the generated interference fringes provided in this application; Figure 9 Schematic diagram of the structure of the electrostriction coefficient measurement device based on the Loey mirror interferometry method provided in this application; Figure 10 A physical diagram of the electrostrictive measurement device based on the Loey mirror interferometry method provided in this application; Explanation of the accompanying drawings in the specification: 1. light source; 2. power supply; 3. sample to be tested; 4. support block; 5. reflector; 6. light screen; 7. image processing module; 8. host computer; 9. support table; 10. iron frame. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0020] See also Figure 4 , Figure 4 The figure shows a flow chart of the electrostriction coefficient measurement method based on the Loey mirror interferometry provided by the present application, which specifically includes: S10: applying voltage to the sample to be tested to change the deformation of the sample to be tested, so as to change the reflection angle of the reflector to the laser emitted by the light source, thereby generating interference fringes corresponding to different voltage values ​​on the light screen.

[0021] Specifically, in some embodiments of the present application, it is possible to use Figure 3 The device shown changes the deformation of the sample to be tested by changing the voltage value applied to the sample to be tested, thereby generating interference fringes corresponding to different voltage values ​​on the light screen.

[0022] Optionally, the voltage value applied to the sample to be tested may be randomly changed, or the voltage value applied to the sample to be tested may be linearly increased or decreased, thereby controlling the deformation of the sample to be tested to linearly increase or decrease.

[0023] S20: Based on the Lloyd's mirror interference principle and the triangle similarity principle, a first relationship function is constructed between the deformation of the sample to be tested and the change in the fringe coordinates of the interference fringes; based on the piezoelectric effect, a second relationship function is constructed between the electrostrictive coefficient, voltage value, and deformation of the sample to be tested.

[0024] S30: Based on the first relationship function and the second relationship function, construct a third relationship function between the voltage value and the stripe coordinate change.

[0025] S40: Based on the third relationship function and the fringe coordinates of the interference fringes with the maximum or minimum brightness value corresponding to different voltage values, a linear correlation coefficient between the voltage value and the change in the fringe coordinates is obtained by fitting.

[0026] S50: Calculating the electrostrictive coefficient of the sample to be measured based on the linear correlation coefficient, the size of the sample to be measured, the distance between the reflector and the light source, the size of the reflector, and the distance between the light source and the light screen.

[0027] Specifically, the present application calculates the electrostrictive coefficient of the sample to be tested based on the Loey mirror interference principle and the piezoelectric effect, such as Figure 5 The figure shows a schematic diagram of the Lloyd's mirror interference principle. In the figure, M is a horizontally placed reflector, S1 is a slit, S2 is the virtual image of S1 formed by the reflector M, P is the observation screen, a represents the distance between the light source and M, l represents the length of M, D represents the vertical distance between S1 and P, and A represents the distance between S1 and P.

[0028] When the incident light enters the reflector at a grazing angle of incidence from S1, the reflected light (equivalent to the light beam emitted from S2) and the light beam emitted directly from S1 come from the same wavefront and therefore have the characteristics of coherent light. At the same time, since the range of the reflected light beam output by the reflector overlaps with the light beam emitted directly from S1, the two beams of light interfere in the overlapping area, forming interference fringes. Specifically, the interference fringes are approximately parallel straight stripes with equal spacing.

[0029] When the height of the reflector M changes, its reflection angle changes accordingly, and the overlapping area of ​​the output reflected light beam and the light beam emitted directly from S1 changes, thereby changing the formed interference fringes. Based on this principle, the present application obtains different interference fringes generated on the light screen when the sample to be tested has different deformation amounts. By measuring the displacement of the interference fringes, the deformation amount of the sample to be tested can be accurately calculated, thereby obtaining its electrostrictive coefficient.

[0030] When the sample to be tested is Figure 6 When the tubular structure is shown in FIG, a voltage is applied to the inner and outer walls of the sample to be tested. , which can cause the sample to be tested to deform under the action of the electric field E. The electric field E is expressed as: , Under the piezoelectric effect, the deformation of the sample to be tested The linear relationship between and the electric field is: , in, is the electrostrictive coefficient of the sample to be tested, is the deformation of the sample under test under the action of voltage; is the size of the sample to be tested along the deformation direction.

[0031] Specifically, based on the above derivation, the second relationship function among the electrostriction coefficient, voltage value, and deformation amount of the sample to be tested in step S20 is expressed as: , in, Indicates the electrostrictive coefficient of the sample to be tested; Indicates the deformation of the sample to be tested; Indicates the size of the sample to be tested along the deformation direction; Indicates the size of the sample to be tested in the direction perpendicular to the deformation direction; Indicates the voltage value of the power supply.

[0032] Due to the axial deformation of the sample under voltage It is a tiny amount and difficult to measure accurately, so it is necessary to construct different deformation variables. and the displacement of interference fringes The relationship between and is used to obtain the electrostrictive coefficient of the sample to be tested; Further, if Figure 7 As shown, the axial deformation of the sample under voltage and According to the triangle similarity principle: , From the above formula, we can get and Satisfies the relationship: , Further, if Figure 8 As shown, according to the triangle similarity principle, we can get: , in, represents the fringe coordinates of the interference fringes; Transforming the above formula we can get: , , Furthermore, in step S20, the first relationship function between the deformation of the sample to be measured and the change in the fringe coordinates of the interference fringes is: , in, Indicates the deformation of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the change in the fringe coordinates of the interference fringes.

[0033] Furthermore, by substituting the first relationship function into the second relationship function, a third relationship function between the voltage value and the change in the stripe coordinates can be obtained: , in, Indicates the change in the fringe coordinates of the interference fringes; Indicates the electrostrictive coefficient of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the size of the sample to be tested along the deformation direction; Indicates the size of the sample to be tested in the direction perpendicular to the deformation direction; Indicates the voltage value of the power supply.

[0034] Furthermore, since the third relationship function represents the relationship between the voltage value and the change in the fringe coordinates, and there is a linear relationship between the voltage value and the change in the fringe coordinates, by calculating the difference in the fringe coordinates in the interference fringes corresponding to different voltage values, and substituting the corresponding difference and voltage value into the third relationship function, the linear correlation coefficient between the voltage value and the change in the fringe coordinates can be fitted.

[0035] Specifically, in step S40, based on the third relationship function and the fringe coordinates of the interference fringes with the maximum or minimum brightness value corresponding to different voltage values, the linear correlation coefficient between the voltage value and the fringe coordinate change is obtained by fitting: S400: Converting interference fringes corresponding to different voltage values ​​into fringe coordinate-brightness curves corresponding to different voltage values, and obtaining fringe coordinates with the maximum or minimum brightness value in the fringe coordinate-brightness curve corresponding to each voltage value.

[0036] S401: Input the third relationship function and the fringe coordinates with the maximum or minimum brightness value in the fringe coordinate-brightness curve corresponding to each voltage value into the Origin software, and obtain a relationship diagram between the voltage value and the fringe coordinate change amount by fitting.

[0037] Optionally, in some embodiments of the present application, the interference fringes corresponding to different voltage values ​​are respectively imported into MATLAB software to generate a fringe coordinate-brightness curve graph corresponding to different voltage values, in which the horizontal axis is the coordinate value of each light and dark fringes in the interference fringes, and the vertical axis is the brightness value of each light and dark fringes; the fringes with the largest or smallest brightness value in each interference fringe are selected as reference fringes, and the displacement of the reference fringes in the interference fringes corresponding to different voltage values ​​is calculated, and the displacement is used as the fringe coordinate change. Then, the Origin software can be used to combine the voltage value, the fringe coordinate displacement and the third relationship function to obtain a fitting relationship graph between the voltage value and the fringe coordinate change, and further obtain the linear correlation coefficient between the voltage value and the fringe coordinate change.

[0038] S402: Obtaining a linear correlation coefficient between the voltage value and the stripe coordinate variation based on a relationship diagram between the voltage value and the stripe coordinate variation.

[0039] Furthermore, the linear correlation coefficient between the fitted voltage value and the fringe variation is: , in, Indicates the linear correlation coefficient between the voltage value and the change in the fringe coordinates; Indicates the electrostrictive coefficient of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the size of the sample to be tested along the deformation direction; Indicates the dimension of the sample to be tested in the direction perpendicular to the deformation direction.

[0040] Furthermore, the electrostrictive coefficient of the sample to be tested can be expressed as: , in, Indicates the electrostrictive coefficient of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the size of the sample to be tested along the deformation direction; Indicates the size of the sample to be tested in the direction perpendicular to the deformation direction; It represents the linear correlation coefficient between the voltage value and the change in the fringe coordinates.

[0041] Furthermore, the present invention also provides an electrostriction coefficient measuring device based on the Loey mirror interferometry method, such as Figure 9 and Figure 10 As shown, the device specifically includes: a light source 1, a power supply 2, a sample to be tested 3, a support block 4, a reflector 5, a light screen 6, an image processing module 7 and a host computer 8.

[0042] The light source 1 is a laser source, which is used to emit laser light so that the laser light is incident on the reflector 5 at a grazing incidence angle.

[0043] The power supply 2 is connected to the sample 3 to be tested, and is used to apply voltage to the sample 3 to be tested, thereby changing the deformation of the sample 3 to be tested.

[0044] Specifically, the power supply 2 is a DC regulated power supply. Figure 6 In the tubular shape shown, the positive electrode of the power supply 2 is connected to the inner wall of the sample 3 to be tested, and the negative electrode of the power supply 2 is connected to the outer wall of the sample 3 to be tested.

[0045] The support block 4 and the sample to be tested 3 are located on the same horizontal plane.

[0046] The reflector 5 is placed on the surface of the sample to be tested 3 and the support block 4, with one end in contact with the sample to be tested 3 and the other end in contact with the support block 4; it is used to reflect the laser and output a reflected light beam corresponding to the current voltage value when the voltage value of the power supply 2 changes.

[0047] By adjusting the height of the reflector 5 and the light source 1, the reflected light beam output by the reflector 5 after reflecting the laser light can interfere with the laser light, thereby generating interference fringes on the light screen 6. For example, before measurement, the positions and angles of the light source 1, reflector 5, and light screen 6 are adjusted so that the light source 1 is nearly parallel to the reflector 5 until alternating light and dark interference fringes appear on the light screen 6, indicating that the reflected light beam output by the reflector 5 has interfered with the laser light emitted by the light source 1.

[0048] Specifically, the sample 3 to be tested will expand or contract under the action of the voltage, thereby raising or lowering the height of the side of the reflector 5 in contact with the sample 3 to be tested. This changes the reflection angle of the laser beam from the reflector 5, changes the overlap area between the reflected beam output by the reflector 5 and the laser beam, and thus changes the interference fringes produced on the light screen 6. Therefore, when the reflector 5 reflects the laser beam based on the reflection angle before and after the voltage value of the power supply 2 changes, it outputs different reflected beams. Based on the overlap area between these reflected beams and the laser beam, different interference fringes can be produced on the light screen 6.

[0049] The light screen 6 is used to generate interference fringes based on the interference light of the reflected light beam output by the reflector 5 and the laser, thereby obtaining interference fringes corresponding to different voltage values.

[0050] The image processing module 7 is connected to the host computer 8 and is used to collect and amplify the interference fringes corresponding to different voltage values ​​and send the interference fringes to the host computer 8.

[0051] Optionally, the image processing module 7 can be any device such as a digital microscope, a CCD camera or a high-speed camera, which can capture the interference fringes generated by the light screen 6 and amplify them.

[0052] The host computer 8 specifically includes: A first relationship function and a second relationship function construction module are used to construct a first relationship function between the deformation amount of the sample to be measured and the fringe coordinate change amount of the interference fringe based on the Lloyd's mirror interference principle and the triangle similarity principle; and to construct a second relationship function between the electrostriction coefficient, voltage value, and deformation amount of the sample to be measured based on the piezoelectric effect; A third relationship function construction module is used to construct a third relationship function between the voltage value and the stripe coordinate change based on the first relationship function and the second relationship function; A linear correlation coefficient acquisition module is used to obtain a linear correlation coefficient between the voltage value and the change in the fringe coordinate based on the third relationship function and the fringe coordinates with the maximum or minimum brightness value in the interference fringes corresponding to different voltage values; The electrostrictive coefficient calculation module is used to calculate the electrostrictive coefficient of the sample to be tested based on the linear correlation coefficient, the size of the sample to be tested, the distance between the reflector and the light source, the size of the reflector, and the distance between the light source and the light screen.

[0053] Optionally, in some embodiments of the present application, the voltage of the power supply 2 may be controlled by the host computer 8 to increase or decrease linearly, thereby causing the deformation of the sample 3 to increase or decrease linearly.

[0054] For example, host computer 8 can control the output voltage of power supply 2 to gradually increase by 10V, so that the deformation of sample 3 changes once every 10V interval, and obtain the interference fringes corresponding to the current voltage value. Compared to using only two interference fringes before and after the deformation of sample 3 changes, using multiple interference fringes corresponding to different deformation values ​​can more accurately determine the electrostriction coefficient of sample 3.

[0055] Further, if Figure 10 As shown, the device further includes a support platform 9 and an iron frame platform 10.

[0056] The support platform 9 is used to place the sample 3 to be tested and the support block 4 .

[0057] The plurality of iron frames 10 are used to fix the light source 1 , the light screen 6 and the image processing module 7 respectively.

[0058] Optionally, the height of the iron frame 10 is adjustable, and the heights of the light source 1 , the light screen 6 and the image processing module 7 can be adjusted by adjusting the height of the iron frame 10 .

[0059] Furthermore, the support platform 9 and the support block 4 are both 3D printed parts.

[0060] Preferably, the height of the support block 4 is equal to the height of the sample 3 to be measured when the deformation amount is 0, so that the reflector 5 can be placed horizontally on the surface of the sample 3 to be measured and the support block 4.

[0061] Furthermore, the size of the contact area between the reflector 5 and the sample 3 to be tested is smaller than the size of the surface of the sample 3 to be tested that contacts the reflector 5 .

[0062] It is worth noting that the size of the contact area between the reflector 5 and the sample 3 is the length of the contact area along the direction connecting the center point of the sample 3 and the center point of the support block 4. For example, when the contact area between the reflector 5 and the sample 3 is circular, the size of the contact area between the reflector 5 and the sample 3 is the diameter of the contact area; when the contact area between the reflector 5 and the sample 3 is square, the size of the contact area between the reflector 5 and the sample 3 is the side length of the contact area.

[0063] For example, Figure 9 and Figure 10 As shown in the figure, the reflector 5 is gently placed on the edge of the sample to be tested 3. This can avoid the problem that the electrostriction coefficient of the sample to be tested 3 is uneven, resulting in different deformation amounts at different positions under voltage excitation, which in turn leads to inaccurate measurement results. During measurement, by changing the contact area between the sample to be tested 3 and the reflector 5, the electrostriction coefficient of different positions of the sample to be tested 3 can be accurately measured.

[0064] Furthermore, when the sample 3 to be tested is a piezoelectric ceramic tube, the positive electrode of the power supply 2 is connected to the inner wall of the piezoelectric ceramic tube, and the negative electrode of the power supply 2 is connected to the outer wall of the piezoelectric ceramic tube.

[0065] The size of the contact area between the reflector 5 and the piezoelectric ceramic tube is smaller than the wall thickness of the piezoelectric ceramic tube.

[0066] In a specific example of the present application, the sample to be tested 3 is a piezoelectric ceramic tube with an outer diameter of 24 mm, an inner diameter of 20 mm, and a height of 23 mm. The length of the reflector 5 is 50 mm and the width is 40 mm. The diameter of the contact area between the reflector 5 and the sample to be tested 3 is less than 2 mm.

[0067] Compared to Figure 3 The electrostriction coefficient measuring device based on the Michelson interferometer method shown in the present application, the electrostriction coefficient measuring device based on the Loewe mirror interferometer method provided in the present application only needs to use one reflector to generate interference fringes, without the need for a beam splitter and multiple reflectors, reducing the number of optical devices, simple structure, easy to disassemble and assemble, easy to carry and operate, and low cost, can be applied to samples to be tested of various sizes, and has wide practicality. The device also has the characteristics of simple operation and repeatable results, which can promote the development of practical teaching, and is easy to carry, easy to disassemble and assemble, and is suitable for demonstration in physics and optics popular science lectures. In addition, the device can also be used in the field of industrial detection. By accurately measuring the electrostriction coefficient of the material to be tested, problems in the product production process can be discovered in a timely manner, the reliability and durability of the product can be improved, the consistency of product quality and performance can be ensured, rapid detection of the production line can be achieved, and the industrial production efficiency and field competitiveness can be significantly improved.

[0068] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0069] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0070] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0071] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0072] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for measuring electrostriction coefficient based on Loey mirror interferometry, characterized in that: include: Applying voltage to the sample to be tested to change the deformation of the sample to be tested, so as to change the reflection angle of the reflector to the laser emitted by the light source, thereby generating interference fringes corresponding to different voltage values ​​on the light screen; Based on the Lloyd's mirror interference principle and the triangle similarity principle, a first relationship function between the deformation amount of the sample to be tested and the fringe coordinate change amount of the interference fringe is constructed; Constructing a second relationship function among the electrostriction coefficient of the sample to be tested, the voltage value, and the deformation amount of the sample to be tested based on the piezoelectric effect; Based on the first relationship function and the second relationship function, construct a third relationship function between the voltage value and the stripe coordinate change amount; Based on the third relationship function and the fringe coordinates of the interference fringes with the maximum or minimum brightness value corresponding to different voltage values, a linear correlation coefficient between the voltage value and the fringe coordinate change is obtained by fitting; The electrostriction coefficient of the sample to be tested is calculated based on the linear correlation coefficient, the size of the sample to be tested, the distance between the reflector and the light source, the size of the reflector, and the distance between the light source and the light screen.

2. The method for measuring the electrostriction coefficient based on the Loey mirror interferometry according to claim 1, characterized in that: The first relationship function is: ， in, Indicates the deformation of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the change in the fringe coordinates of the interference fringes.

3. The method for measuring the electrostriction coefficient based on the Loey mirror interferometry according to claim 1, characterized in that: The second relationship function is: ， in, Indicates the electrostrictive coefficient of the sample to be tested; Indicates the deformation of the sample to be tested; Indicates the size of the sample to be tested along the deformation direction; Indicates the size of the sample to be tested in the direction perpendicular to the deformation direction; Indicates the voltage value of the power supply.

4. The method for measuring the electrostriction coefficient based on the Loey mirror interferometry according to claim 1, characterized in that: The third relationship function is: ， in, Indicates the change in the fringe coordinates of the interference fringes; Indicates the electrostrictive coefficient of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the size of the sample to be tested along the deformation direction; Indicates the size of the sample to be tested in the direction perpendicular to the deformation direction; Indicates the voltage value of the power supply.

5. The method for measuring the electrostriction coefficient based on the Loey mirror interferometry according to claim 1, characterized in that: The linear correlation coefficient between the voltage value and the fringe coordinate change is: ， in, Indicates the linear correlation coefficient between the voltage value and the change in the fringe coordinates; Indicates the electrostrictive coefficient of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the size of the sample to be tested along the deformation direction; It indicates the dimension of the sample to be tested in the direction perpendicular to the deformation direction.

6. The method for measuring the electrostriction coefficient based on the Loey mirror interferometry according to claim 1, characterized in that: The calculation formula of the electrostrictive coefficient of the sample to be tested is: ， in, Indicates the electrostrictive coefficient of the sample to be tested; Indicates the size of the reflector; Indicates the distance between the light source and the reflector; Indicates the distance between the light source and the light screen; Indicates the size of the sample to be tested along the deformation direction; Indicates the size of the sample to be tested in the direction perpendicular to the deformation direction; It represents the linear correlation coefficient between the voltage value and the change of the fringe coordinates.

7. The method for measuring the electrostriction coefficient based on the Loey mirror interferometry according to claim 1, characterized in that: Based on the third relationship function and the fringe coordinates with the maximum or minimum brightness value in the interference fringes corresponding to different voltage values, the linear correlation coefficient between the voltage value and the fringe coordinate change obtained by fitting includes: The interference fringes corresponding to different voltage values ​​are converted into fringe coordinate-brightness curve graphs corresponding to different voltage values, and the fringe coordinates with the maximum or minimum brightness value in the fringe coordinate-brightness curve graph corresponding to each voltage value are obtained; The third relationship function and the fringe coordinates with the maximum or minimum brightness value in the fringe coordinate-brightness curve graph corresponding to each voltage value are input into the Origin software, and a relationship graph between the voltage value and the fringe coordinate change amount is obtained by fitting; A linear correlation coefficient between the voltage value and the stripe coordinate change amount is obtained based on the voltage value and stripe coordinate change amount relationship diagram.

8. An electrostriction coefficient measuring device based on the Loey mirror interferometry method, characterized in that: The method for measuring the electrostriction coefficient based on the Loey mirror interferometry method according to any one of claims 1 to 7 comprises: A light source, configured to emit laser light so that the laser light is incident on the reflector at a grazing angle of incidence; A power supply, connected to the sample to be tested, and used to apply voltage to the sample to be tested, thereby changing the deformation amount of the sample to be tested; A support block, located at the same horizontal plane as the sample to be tested; A reflector, placed on the surface of the sample to be tested and the support block, with one end in contact with the sample to be tested and the other end in contact with the support block; used to reflect the laser and output a reflected light beam corresponding to the current voltage value when the voltage value of the power supply changes; A light screen, used to generate interference fringes based on the interference light of the reflected light beam and the laser, so as to obtain interference fringes corresponding to different voltage values; An image processing module, connected to a host computer, for collecting and amplifying interference fringes corresponding to the different voltage values, and sending the interference fringes to the host computer; The host computer includes: A first relationship function and a second relationship function construction module, for constructing a first relationship function between the deformation amount of the sample to be tested and the fringe coordinate change amount of the interference fringe based on the Loey mirror interference principle and the triangle similarity principle; and constructing a second relationship function between the electrostriction coefficient of the sample to be tested, the voltage value, and the deformation amount of the sample to be tested based on the piezoelectric effect; A third relationship function construction module, used to construct a third relationship function between a voltage value and a stripe coordinate variation based on the first relationship function and the second relationship function; A linear correlation coefficient acquisition module, used to fit the linear correlation coefficient between the voltage value and the change amount of the fringe coordinates based on the third relationship function and the fringe coordinates with the maximum or minimum brightness value in the interference fringes corresponding to different voltage values; The electrostriction coefficient calculation module is used to calculate the electrostriction coefficient of the sample to be tested based on the linear correlation coefficient, the size of the sample to be tested, the distance between the reflector and the light source, the size of the reflector, and the distance between the light source and the light screen.

9. The electrostriction coefficient measuring device based on the Loey mirror interferometry method according to claim 8, characterized in that: Also includes: A support table, used for placing the sample to be tested and the support block; A plurality of iron frames are used to fix the light source, the light screen and the image processing module respectively.

10. The electrostriction coefficient measuring device based on the Loey mirror interferometry method according to claim 8, characterized in that: The size of the contact area between the reflector and the sample to be tested is smaller than the size of the surface of the sample to be tested that contacts the reflector.

Images