CN103616127A - Source tracing calibrating device and source tracing method for micro cantilever beam elastic constant - Google Patents

Abstract

The invention provides a micro-cantilever beam elastic constant traceability calibration device, the structure of the traceability calibration device includes a marble frame, a nanoscale balance, a micro-cantilever beam, a three-dimensional micro-nano displacement stage, a force loading rod, a polarization differential interferometer, and an instrument control device, computer and measurement and control software. At the same time, it provides a traceability method for the traceability calibration device of the elastic constant of the micro-cantilever beam. The effect of the invention is that the elastic constant value can be directly traced to the international system of units SI by using the device. The device completely coincides the micro-spot formed by the measuring beam of the polarization differential interferometer on the upper surface of the free end of the micro-cantilever with the force loading point when the force-loading rod on the nanobalance loads the lower surface of the free end of the micro-cantilever and is aligned with the direction of gravity. Consistency makes the Abbe arm zero, complies with the Abbe principle of displacement measurement, avoids the Abbe error, and ensures the measurement accuracy of the traceability instrument. It can ensure the uniformity, reliability and comparability of micro-force measurements performed by different laboratories using micro-cantilever beams.

Description

Traceability Calibration Device and Traceability Method for Elastic Constant of Microcantilever Beam

technical field

The invention belongs to the intersecting field of nanotechnology and metrology, and relates to a traceability calibration device and a traceability method for the elastic constant of a micro-cantilever beam.

Background technique

The three-dimensional dimensions of the length, width and thickness of the micro-cantilever range from a few nanometers (nano-meter) to hundreds of micrometers (micro-meter). When in use, one end is generally fixed and the other end is free to form an elastic element. Microcantilever is an important sensing element on the micro-nano scale. It is often used as a force sensor to detect tiny physical, chemical and biological forces, and is also used to measure physical quantities such as temperature and medium viscosity. As an elastic sensing element, the micro-cantilever obeys Hooke's law, that is, F=kΔz, where k is the elastic constant of the micro-cantilever, and Δz is the displacement of the free end. It can be seen that the force measurement accuracy of the micro-cantilever depends on the accurate measurement of the elastic constant k.

For this reason, scholars have proposed a variety of methods for the measurement of the elastic constant of micro-cantilever beams, which are mainly divided into two categories: static methods and dynamic methods: static methods include calculation methods, reference beam methods, loading methods, etc.; dynamic methods include Mass addition method, Sader method and thermal noise calibration method. But up to now, these methods are based on theoretical formulas derived from the physical properties and dimensions of micro-cantilever beams, combined with experiments to measure elastic constants, and have not been traced back to the International System of Units SI. This makes it difficult to compare the force measurement data between various laboratories using micro-cantilever beams for micro-force testing because there is no unified reference standard, and even leads to misunderstanding of objective phenomena. Tracing the elastic constant of the microcantilever to the international unit SI has become an urgent task in the application field of the microcantilever.

Scholars have also proposed some schemes for the traceability calibration of elastic constants of micro-cantilever beams, such as Physikalisch-Technische Bundesanstalt (PTB) and Korea Research Institute of Standards and Science (KRISS). ) combines the micro-nano displacement stage with the nano-balance, uses the capacitive displacement sensor integrated on the micro-nano displacement stage to trace the source of displacement, and uses the nano-balance to trace the source of force, but this structure uses a capacitive sensor to measure displacement, and the capacitive sensor itself It needs to be calibrated with a laser interferometer to trace the source, so the device itself does not trace the direct value of the elastic constant to the international unit SI; not only that, because the capacitive sensor that measures the displacement of the free end of the micro-cantilever beam is not in a straight line with the force loading point on the free end On the other hand, there is a large distance between the two, that is, the Abbe arm, which violates the Abbe principle of displacement measurement, making the system have a large error, and it is difficult to guarantee the measurement accuracy. Therefore, this device is also not suitable as a traceable calibration device for the elastic constant of the micro-cantilever beam. Some scholars have also proposed a plan to use optical levers as displacement measurement, but since the actual measurement of the polished rod is the deflection angle of the micro-cantilever rather than the displacement, this solution cannot directly trace the elastic constants to the International System of Units SI.

Contents of the invention

The invention provides a micro-cantilever beam elastic constant traceability calibration device and a traceability method, so as to realize the direct traceability of the micro-cantilever beam elastic constant and SI, avoid the occurrence of Abbe error, and ensure the measurement accuracy of the traceability instrument.

In order to achieve the above object, the technical solution adopted in the present invention is to provide a micro-cantilever beam elastic constant traceability calibration device, the structure of the traceability calibration device includes a marble frame, a nanobalance, a micro-cantilever beam, a three-dimensional micro-nano displacement stage, a force Loading rod, polarization differential interferometer, instrument controller, computer and measurement and control software.

At the same time, it provides a traceability method for the traceability calibration device of the elastic constant of the micro-cantilever beam.

The effect of the invention is that the elastic constant value can be directly traced to the international system of units SI by using the device. The device completely coincides with the micro-spot formed by the measuring beam of the polarization differential interferometer on the upper surface of the free end of the micro-cantilever beam and the force loading point when the force-loading rod on the nanobalance loads the lower surface of the free end of the micro-cantilever beam and is aligned with the direction of gravity. Consistency makes the Abbe arm zero, complies with the Abbe principle of displacement measurement, avoids the Abbe error, and ensures the measurement accuracy of the traceability instrument. It can ensure the uniformity, reliability and comparability of micro-force measurements performed by different laboratories using micro-cantilever beams.

Description of drawings

Fig. 1 Schematic diagram of the traceable calibration device for the elastic constant of the micro-cantilever beam;

Fig. 2 Force-displacement array obtained by step loading and its fitted straight line.

In the picture:

1. Marble frame 2. Nano balance 3. Micro cantilever beam 4. Three-dimensional micro-nano displacement stage 5. Force loading rod 6. Polarization differential interferometer 7. Device controller 8. Computer and measurement and control software 9. X-direction single-axis micro-nano Displacer 10, y-direction uniaxial micro-nano displacement device 11, z-direction uniaxial micro-nano displacement device 12, elastic clamp 13, He-Ne polarization laser 14, Faraday optical isolator 15, Sorey-Babignet compensator 16. Beam expander 17. Beam splitter 18. Focusing lens 19. Wollaston prism A 20. Wollaston prism B 21. Photodiode A22, photodiode 23, optical path box 24, photoelectric signal processing module 25 ,Optical microscope

Detailed ways

The micro-cantilever elastic constant traceability calibration device and traceability method of the present invention will be described in conjunction with the accompanying drawings.

The traceability and calibration device for the elastic constant of the micro-cantilever beam of the present invention is based on the design idea of the traceability calibration device based on the use of a polarization differential interferometer as the displacement measurement means of the free end of the micro-beam, and realizes the traceability with the length unit meter (m) in the International System of Units; As a means of force measurement, the nanobalance realizes the traceability with Newton (N), the unit of force in the International System of Units. The traceability method according to the traceability calibration device is characterized in that the force-displacement curve of the microcantilever is obtained through experiments, and then the elastic constant traceability value of the microcantilever is obtained by straight line fitting and calculating the average value of the slope. In the traceability device, the micro-spot formed on the upper surface of the micro-cantilever by the measuring beam of the reflective differential interferometer is on the same straight line as the force loading point of the nanobalance on the lower surface of the micro-cantilever through the force-loading rod, And keep in line with the gravitational (vertical) direction.

As shown in Figures 1 and 2, the structure of the micro-cantilever beam elastic constant calibration device of the present invention is to include a marble frame 1, a nanobalance 2, a micro-cantilever beam 3, a three-dimensional micro-nano displacement platform 4, and be fixed on the nanometer The force loading rod 5 on the balance, the polarization differential interferometer 6, the instrument controller 7, the computer and the measurement and control software 8 are composed of several parts.

The marble frame 1 is the supporting structure of the mechanical part of the device. The marble material is selected as the supporting structure because marble has high density, high strength, high hardness, good stability, wear resistance and pressure resistance, no rust, no magnetization, and It has the advantages of small acid-base, thermal expansion coefficient and no large deformation due to room temperature fluctuations. The marble frame 1 is fixed with three modules including a nanobalance 2 , a three-dimensional micro-nano displacement stage 4 and an optical path box 23 of a reflective differential interferometer 6 . The nanobalance 2 is designed and manufactured according to the principle of electromagnetic balance, with a mass resolution of 0.01 mg and a measuring range of 2.1 g. A powerful loading rod 5 is fixed on the top of the nanobalance. The force loading rod 5 is made of high-hardness materials, such as silicon, and its main body is cylindrical with a diameter of 2 to 3 mm. The center of the top is in the shape of a hemispherical crown. The top center of the crown is the loading point for applying the load to the free end of the microcantilever. The three-dimensional micro-nano displacement stage is composed of an x-direction uniaxial micro-nano displacement device 9, a y-direction uniaxial micro-nano displacement device 10 and a z-direction uniaxial micro-nano displacement device 11, and the x-direction, y-direction and z-direction single-axis The axis micro-nanodisplacers are orthogonal to each other. An elastic clamp 12 is fixed at the bottom of the z-direction uniaxial micro-nano displacement device 11 , and the micro-cantilever beam 3 is fixed on the z-direction micro-nano displacement device 11 through the elastic clamp 12 . The z-direction uniaxial micro-nano displacement device 11 is fixed on the y-direction micro-nano displacement device 10, and the y-direction micro-nano displacement device 10 is fixed on the x-direction micro-nano displacement device 9, so by By adjusting the x-direction, y-direction and z-direction micro-nano displacement, the spatial position of the micro-cantilever beam can be adjusted. The strokes of the x-direction, y-direction and z-direction uniaxial micro-nano displacement device are all hundreds of μm-1mm, and the displacement resolution is 1-10nm.

The polarization differential interferometer 6 is composed of a He-Ne polarization laser 13, a Faraday optical isolator 14, a Sorey-Babignet compensator 15, a beam expander 16, a beam splitter 17, a focusing lens 18, and a Thompson Glan prism 19 , a Wollaston prism 20, a photodiode 21, a photodiode 22, an optical path box 23, and a photoelectric signal processing module 24. The optical path box 23 includes the laser 13, Faraday optical isolator 14, Sorey-Babignet compensator 15, beam expander 16, beam splitter 17, focusing lens 18, Wollaston prism A19, Wollaston prism B20, photodiode A21, photodiode B22, etc., and the interior is painted black to reduce the interference of stray light. The basic working principle of this optical path is that the He-Ne polarized laser 13 is a laser that emits mixed p-state and s-state polarized light beams. After the light beam passes through the Faraday optical isolator 14, it forms p-state and s-state polarized light with equal light intensity and orthogonal to each other. After the light beam enters the Sorey-Babignet compensator 15, the phase Φ of the output p-state and s-state polarized light will be modulated by the Sorey-Babignet compensator. Then, after the beam passes through the beam expander 16, it becomes a beam with a larger beam diameter and uniform energy distribution. After the expanded beam enters the beam splitter 17, part of it is refracted and the other part is transmitted to form two beams. The beam transmitted from the beam splitter 17 passes through the focusing lens 18 to form a focused beam, and then enters the Wollaston prism A19 to form the p-state and s-state polarized light that are spatially separated from each other .

The p-state polarized light is irradiated onto the upper surface of the free end of the micro-cantilever beam 3 and reflected back as a measuring beam. The s-state polarized light is irradiated onto the fixed end of the micro-cantilever beam as a reference beam. The p-state and s-state polarized light reflected from the free end and the fixed end of the micro-cantilever beam 3 return along the original path, and after passing through the Wollaston prism A19 and the focusing lens 18, they are captured by the The beam splitter 17 is refracted to the Wollaston prism 20, where it interferes with the p-state and s-state polarized light refracted from the beam splitter 17 to 21 for the first time and spatially separated from each other to form the interfering p-state polarized light and s-state polarized light, which are respectively received by the photodiode A21 and photodiode B22, and the electrical signal is received by the photoelectric signal processing circuit module 24 to obtain the microcantilever Displacement information of the free end of beam 3.

The structural relationship between the free end displacement 1 of the micro-cantilever beam 3 and the photodiode A21, photodiode B22 and the photoelectric signal processing module 24 is that the output electrical signal of the photodiode A21 and photodiode B22 respectively reflect the interference information of the p-state polarized light and the interference information of the s-state polarized light, and the phase difference signal Φ between the two reflects the displacement change of the free end of the micro-cantilever beam 3 . In fact, the phase difference signal Φ of the p-state and s-state interference polarized light is determined by three parts, that is, the phase shift θ introduced by the free end of the micro-cantilever 3, the Sorey-Babignet compensator 15 The introduced phase shift Ψ and the fixed phase shift ζ caused by other optical elements in the optical path. Adjusting the Sorey-Babignet compensator 15 can make its phase shift Ψ=-ζ. In this way, the displacement value l of the free end of the micro-cantilever beam 3 can be obtained by using the phase shift between the p-state and s-state polarized light interference signals, which is completed by the signal processing circuit module 24 and passed through Device controller 7 transmits to computer and measurement and control software 8. The free end of the microcantilever beam 3 is subjected to the force value applied by the force loading rod 5, and the mass value m is read out by the nanobalance, and is transmitted to the computer and measurement and control software 8 by the instrument controller 7 , in the measurement and control software, multiply the mass value m by the local gravitational acceleration g value to obtain the force value f.

In order to facilitate the determination of the spot positions of the p-state and s-state polarized light beams on the micro-cantilever 3 and the position of the loading point of the force-loading rod 5 on the micro-cantilever 3 , an optical microscope 25 is provided.

Abbe's principle must be followed to achieve high-accuracy measurement. The Abbe principle requires that the measurement axis of the measuring element coincides completely with the axis of the measured displacement, otherwise the distance between the two axes, which is called the Abbe arm, will cause a large error, which is called the Abbe error. The larger the Abbe arm, the larger the Abbe error in the measurement. The Abbe principle must be followed in micro-displacement measurement. On the one hand, at the micro-nano level, the Abbe arm will be relatively larger, resulting in a larger Abbe error. Moreover, Abbe error is difficult in micro-nano measurement. Assessment and Compensation. As mentioned above, the Abbe arms in the elastic constant measuring instruments of PTB in Germany and KRISS in Korea have reached 10-20 mm. Compared with the range of several μm to hundreds of μm, this larger Abbe arm will inevitably bring to a large Abbe error. Moreover, they did not analyze the Abbe error and do not compensate the instrument, which shows that it is very difficult.

In the micro-cantilever elastic constant calibration device of the present invention, the measuring element is the reflection differential interferometer, and the corresponding measurement axis is the p-state polarized light beam irradiated to the free end of the micro-cantilever 3, and the measured displacement It is the displacement at the contact point between the vertex of the spherical cap of the force loading rod 5 and the lower surface of the free end of the micro-cantilever beam 3 , that is, the force loading point. In this way, by means of the optical microscope 25, adjusting the three-dimensional micro-nano displacement platform 4 can make the light spot formed by the p-state polarized light beam on the micro-cantilever beam 3 coincide with the ball of the force-loaded rod 5. The contact point between the crown central vertex and the free end of the micro-cantilever 3 is on the same vertical line, that is, the Abbe arm is 0; at the same time, during the loading process, it is guaranteed that the p-state polarized light beam, the micro-cantilever 3 The directions of the loading points of the free end force are all in the vertical direction, so that the device complies with Abbe's principle, which can ensure the high accuracy of calibration.

The traceability method steps of the microcantilever beam elastic constant traceability calibration device are as follows:

1. Power on and preheat the device: Turn on the micro-cantilever beam elastic constant traceability calibration device, power on the device and preheat it. After the preheating reaches 120 minutes, the device starts to work normally.

2. Measurement of gravitational acceleration: use a precision gravitational velocity meter to measure the g value of the gravitational acceleration at the location of the instrument.

3. Device level adjustment: use an electronic level to adjust the device level, so that the marble frame 1 and the nanobalance 2 fixed thereon are in a horizontal state, and at the same time, install the force loading rod 5 on the nanobalance 2 , the p-state and s-state polarized light beams irradiated to the free end of the micro-cantilever beam 3 are also in a vertical state.

4. The coincidence adjustment of the force loading position and the measurement beam: with the help of the optical microscope 26, the force loading rod is placed through the x-direction uniaxial micro-nano displacement device 9 and the y-direction uniaxial micro-nano displacement device 10 The force loading point of the top center of the spherical cap of 5 on the lower surface of the free end of the micro-cantilever is on the same vertical line as the p-state light beam on the free end of the micro-cantilever 3 to be measured.

5. Zero position adjustment: with the help of the optical microscope 26, adjust the z-direction uniaxial micro-nano displacement device 11, so that the micro-cantilever moves down until the top center of the spherical cap of the force loading rod 5 is in line with the The lower surface of the free end of the micro-cantilever 3 is just in contact, that is, the force load exerted by the force loading rod on the free end of the micro-cantilever is just zero, that is, the output of the nanobalance 2 to the The quality value in the above-mentioned computer and measurement and control software is 0, and moving the micro-cantilever beam further downwards will immediately make the output quality value of the nanobalance 2 begin to increase, then this position is the measurement zero point of the force load; and at this time , the displacement value of the free end of the micro-cantilever beam 3 transmitted to the computer and measurement and control software by the polarization differential interferometer 6 is set to 0, that is, this position is also the displacement zero point at the same time.

6. Acquisition of the force-displacement curve of the micro-cantilever beam 3:

1) The array A _j ( _xi , y _i ) is set to represent force-displacement data. Among them, x _i is the displacement value, y _i is the corresponding force value; j=1,2,...,m is the number of experiments, generally m can be taken between 5 and 8 times, and a set of force-displacement data is obtained for each experiment , corresponding to a force-displacement curve, taking multiple experiments and taking the average value is to reduce the random error and improve the calibration accuracy; Initially, the number of progressive loadings with s as the displacement increment is generally between 1 and 20 nm. When i=0, it represents the displacement value and force value of the free end of the micro-cantilever beam at the zero point. The force value can be obtained from the product of the output value of the nanobalance and the acceleration of gravity. Obviously, x ₀ =0, y ₀ =0; When i=1, it means the loading of the first feeding amount of s, at this time, x ₁ =s, y ₁ is the corresponding force value; and so on, when i=n, it means the nth feeding amount is the loading of s, at this time, x _n = ns, and y _n is equal to the corresponding force value.

2) Zero position adjustment: with the help of the optical microscope 26, adjust the z-direction uniaxial micro-nano displacement device 11, so that the micro-cantilever moves down until the top center of the spherical cap of the force loading rod 5 is in line with the The lower surface of the free end of the micro-cantilever 3 is just in contact, that is, the force load exerted by the force loading rod on the free end of the micro-cantilever is just zero, that is, the output of the nanobalance 2 to the The quality value in the above-mentioned computer and measurement and control software is 0, and moving the micro-cantilever beam further downwards will immediately make the output quality value of the nanobalance 2 begin to increase, then this position is the measurement zero point of the force load; and at this time , the displacement value of the free end of the micro-cantilever beam 3 transmitted to the computer and measurement and control software by the polarization differential interferometer 6 is set to 0, that is, this position is also the displacement zero point at the same time.

3) Acquisition of step loading and force-displacement curves: through the z-direction uniaxial micro-nano displacement device 11, move the micro-cantilever beam 3 downward with a certain step, such as 10 nm, step value The data measured by the polarization interferometer 6 are transmitted to the computer and measurement and control software 8 through the instrument controller 7, and displayed on the computer monitor. Simultaneously, in the process that described micro-cantilever beam 3 moves downward, the free end of micro-cantilever beam 3 will be subjected to the power load from described force loading bar 5, and the value of institute's force load can be determined by described nanometer The product of the mass value output by the balance 2 and the acceleration of gravity g is obtained. The mass value of the nanobalance 2 is also transmitted to the computer and measurement and control software 8 through the instrument controller 7, and displayed on the computer monitor. The displacement value and force value at this position are represented by an array A ₁ (x ₁ ,y ₁ ). By repeating this stepping process, A ₁ (x ₂ ,y ₂ ), A ₁ (x ₃ ,y ₃ ),…, A ₁ ( _xi ,y _i ),…, A ₁ (x _n ,y _n ). Then the array A ₁ (xi _, y _i ) (i=0-n) reflects the relationship between the force value and the displacement value at different positions of the micro-cantilever beam 3 during the loading process starting from the zero point. Take x _i (where i=0,1,2,…,n) in the array A _i (xi ,y _i ) as the abscissa, and take y _i (where i=0,1,2,… _, n) Draw the force-displacement curve for the ordinate, as shown in Figure 2, the force-displacement array A _j (x _i , y _i ) and the straight line obtained by least squares fitting.

7. Calculation of the traceable value of the elastic constant: A _j (x _i , y _i ) are respectively fitted to a straight line y=K _j x by the least square method, then the traceable elastic constant of the micro-cantilever beam obtained by j experiments The value k is the arithmetic mean of _Kj , that is:

$\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; .</span>$

The motion of the micro-cantilever beam 3 of the micro-cantilever beam elastic constant traceability device of the present invention is driven by the micro-nano displacement platform, and in the process of force loading, the force load on the free end of the micro-cantilever beam 3 is measured by the quality value of the nanobalance and The product of the acceleration of gravity is obtained, and the displacement is measured by the reflection differential interferometer. In this device, the micro-spot formed on the upper surface of the free end of the micro-cantilever completely coincides with the force loading point when the force-loading rod on the nanobalance loads the lower surface of the free end of the micro-cantilever and is consistent with the direction of gravity, so that Abbe The arm is zero, which complies with the Abbe principle of displacement measurement, avoids the Abbe error, and ensures the measurement accuracy of the traceable instrument.

Claims (6)

1. A traceable calibration device for the elastic constant of a micro-cantilever beam, characterized in that: the structure of the traceable calibration device includes a marble frame (1), a nanobalance (2), a micro-cantilever beam (3), a three-dimensional micro-nano displacement Platform (4), force loading rod (5), polarization differential interferometer (6), instrument controller (7), computer and measurement and control software (8); The marble frame (1) is fixed with a nanobalance (2), a three-dimensional micro-nano displacement stage (4) and an optical path box (23) of a reflection differential interferometer (6), and the nanobalance (2) The top is fixed with a powerful loading rod (5), the microcantilever beam (3) is fixed on the nanobalance (2), and a computer and measurement and control software (8) are installed on one side of the marble frame (1), and the instrument controller (7) and The computer is connected with the measurement and control software (8). 2. The traceable calibration device for the elastic constant of the micro-cantilever beam according to claim 1, characterized in that: the main body of the force loading rod (5) is cylindrical, with a diameter between 2 and 3 mm, and the top is in the shape of a hemispherical crown , the radius of the spherical cap is 10-50 μm, and the top center of the spherical cap is a loading point for applying load to the free end of the micro-cantilever beam (3). 3. The traceable calibration device for the elastic constant of the micro-cantilever beam according to claim 1, characterized in that: the three-dimensional micro-nano displacement stage (4) includes an x-direction single-axis micro-nano displacement device (9), a y-direction single-axis Axis micro-nano displacement (10) and z-direction uniaxial micro-nano displacement (11), the z-direction uniaxial micro-nano displacement (11) is fixed on the y-direction micro-nano displacement (10), The y-direction micro-nano displacement device 10 is fixed on the x-direction micro-nano displacement device (9), the x-direction uniaxial micro-nano displacement device (9), the y-direction uniaxial micro-nano displacement device (10) and the z-direction uniaxial micro-nano displacement device (11) are orthogonal to each other, the bottom of the z-direction uniaxial micro-nano displacement device (11) is fixed with an elastic clamp (12), and the micro-cantilever beam (3) passes through the The elastic clamp (12) is fixed on the z-direction uniaxial micro-nano displacement device (11). 4. The traceable calibration device for the elastic constant of the micro-cantilever beam according to claim 1, characterized in that: the polarization differential interferometer (6) includes He-Ne polarized lasers sequentially fixed in the optical path box (23) (13), Faraday optical isolator (14), Sorey-Barbinet compensator (15), beam expander (16), beam splitter (17), focusing lens (18), Thompson Glan prism (19 ), a Wollaston prism (20), a photodiode (21), a photodiode (22) and a photoelectric signal processing module (24), and the interior of the optical path box (23) is painted black to reduce stray light interference. 5. The traceable calibration device for the elastic constant of the micro-cantilever beam according to claim 1, characterized in that: an optical microscope (25) is arranged on one side of the micro-cantilever beam (3) and the force loading rod (5) . 6. the traceability method of the traceability calibration device of micro-cantilever elastic constant according to claim 1, the method may further comprise the steps: (1) Power on and preheat the device: turn on the traceable calibration device for the elastic constant of the micro-cantilever beam, power on the device and preheat it, and after the preheating reaches 120 minutes, the device starts to work normally; (2) Measurement of gravitational acceleration: use a precision gravitational velocity meter to measure the g value of the gravitational acceleration at the location of the device; (3) Level adjustment of the device: Use an electronic level to adjust the level of the device so that the marble frame (1) and the nanobalance (2) are in a horizontal state, and the force loading rod (5) irradiates the micro balance The p-state and s-state polarized light beams at the free end of the cantilever beam (3) are also vertical; (4) The coincidence adjustment of the force loading position and the measurement beam: with the help of the optical microscope (26), through the x-direction uniaxial micro-nano displacement device (9) and the y-direction uniaxial micro-nano displacement device (10) , measuring the p-state on the free end of the micro-cantilever beam (3) with the force-loading point at the top center of the spherical cap of the force-loading rod (5) on the lower surface of the free end of the micro-cantilever beam (3) The light spot formed by the polarized light on the upper surface of the micro-cantilever beam (3) is on a vertical straight line; (5) Acquisition of the force-displacement curve of the microcantilever (3): 1) Set the array A _j (x _i , y _i ) to represent the force-displacement data, where x _i is the displacement value, y _i is the corresponding force value; j=1,2,...,m is the number of experiments , m is between 5 and 8 times, and each experiment obtains a set of force-displacement data, corresponding to a force-displacement curve, taking multiple experiments and taking the average value; i=0,1,...,n is a single In the loading experiment, the number of progressive loadings starting from position 0 and taking s as the displacement increment is generally between 1 and 20 nm. When i=0, it represents the displacement and force value of the free end of the micro-cantilever beam at the zero point. The force value can be obtained from the product of the output value of the nanobalance (2) and the acceleration of gravity x ₀ =0, y ₀ =0; when i=1, it means that the first feed is s loading, at this time, x ₁ =s, y ₁ is the corresponding force value; and so on, when i=n, it means the loading of the nth feed rate is s, at this time, x _n =ns, y _n is equal to the corresponding force value; 2) Zero position adjustment: with the help of the optical microscope (26), adjust the z-direction uniaxial micro-nano displacement (11), so that the micro-cantilever moves down until the force loading rod (5) The top center of the spherical cap is in contact with the lower surface of the free end of the micro-cantilever beam (3), that is, the force load applied by the force loading rod to the free end of the micro-cantilever beam is exactly zero, that is, the nanobalance (2) passes through the The mass value output by the instrument controller 7 to the computer and measurement and control software is 0, and further downward movement of the microcantilever will immediately cause the output mass value of the nanobalance (2) to begin to increase, then the The position is the measurement zero point of the force load; 3) Acquisition of step loading and force-displacement curve: through the z-direction uniaxial micro-nano displacement device (11), move the micro-cantilever beam (3) downward with a certain step, such as 10nm , the step value will be measured by the polarization interferometer (6), and transmitted to the computer and measurement and control software (8) through the instrument controller (7) and displayed on the computer monitor. During the downward movement of the micro-cantilever beam (3), the free end of the micro-cantilever beam (3) will be subjected to the force load from the force loading rod (5), and the value of the force load is determined by the The product of the mass value output by the nanobalance (2) and the acceleration of gravity g is obtained, and the mass value of the nanobalance (2) is also transmitted to the computer and measurement and control software (8) through the instrument controller (7) and display it on the computer monitor, express the displacement value and force value of the position as an array A ₁ (x ₁ ,y ₁ ), repeat the stepping process, and obtain A ₁ (x ₂ ,y ₂ ), A ₁ ( x ₃ ,y ₃ ),…,A ₁ (xi _, y _i ),…,A ₁ (x _n ,y _n ), then the array A ₁ ( _xi ,y _i ) (i=0,1,2 ,…,n) with x _i ( _i =0,1,2,…,n) in the array A _i (xi ,y _i ) as the abscissa, and y _i (i=0,1,2,… ,n) Draw the force-displacement curve for the ordinate; (6) Calculation of the traceable value of the elastic constant: use the least square method to fit A _j ( _xi , y _i ) to a straight line y=K _j x respectively, then the microcantilever (3) obtained by j experiments The traceable value k of the elastic constant is the arithmetic mean value of K _j , namely: $\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; .</span>$

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