JP2005331509A - Method and device for measuring object by variable natural oscillation cantilever - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring object by a variable natural oscillation cantilever and a device based on this method capable of performing highly accurate measuring by varying the natural frequency of the cantilever in a predetermined range. <P>SOLUTION: In this object measuring device by the variable natural oscillation cantilever, the natural frequency of the cantilever 201 due to the application of light energy from the outside is controlled to be varied in the predetermined range, and characteristics of a substance as a sample are measured by controlling the natural frequency of the cantilever 201. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for measuring an object to be measured using a variable natural vibration type cantilever.

  Conventionally, there are the following two methods for detecting a substance using a cantilever array.

  (1) A substance that reacts with or adsorbs to a substance is previously applied to the cantilever, and the warpage of the cantilever accompanying the substance introduction is detected optically or electrically (see Non-Patent Document 1 below).

  (2) The cantilever is vibrated, and a change in mass associated with substance capture or a change in damping of the cantilever is detected as a change in vibration frequency or vibration amplitude (see Non-Patent Document 2 below).

  Further, the inventors of the present application have proposed the following nanometer-order mechanical vibrator and a measuring apparatus using the same.

  (1) A stable and highly sensitive nanometer order mechanical vibrator having a nanometer order dramatic force and mass change detection resolution and a measuring apparatus using the same (see Patent Document 1 below).

(2) A cantilever that detects a sample surface, a scanning probe microscope using the same, a homodyne laser interferometer, a laser Doppler interferometer having a sample excitation function, and the like (see Patent Document 2 below).
JP 2001-0091441 A JP 2003-0114182 A M.M. K. Baller, H.C. P. Lang, J .; Fritz, Ch. Gerber, J .; K. Gimzewski, U .; Drechsler, H.M. Rothuzen, M.C. Despont, P.M. Vettiger, F.M. M.M. Battiston, J.M. P. Ramseyer, P.M. Fornaro, E .; Meyer, and H.M. -J. Guentherodt: A cantilever array-based artificial nose, Ultramicroscopy, (2000) 1. B. Ilic, D.M. Czaplewski, M.C. Zallutdinov, and H.M. G. Craighead, P.M. Neuzil, C.I. Campagnolo and C.I. Batt: Single cell detection with micromechanical oscillators, J. Batt. Vac. Sci. Technol. B19, (2001), 2825. N. Umeda, S .; Ishizaki, and H.I. Uwai, Scanning Attractive Force Microscope using Photothermal Vibration, J. Am. Vac. Sci. Technol. , B9, (2) 1318.

  When a conventional cantilever type vibrator is vibrated at its natural frequency and used as a sensor, an AFM (atomic force microscope) cantilever or an actuator, the natural frequency is uniquely fixed by its mechanical dimensions. It was.

  That is, conventionally, it is difficult to change the frequency of the cantilever-type vibrator, and there is a method of changing the length of the cantilever using a microactuator or the like, but the structure becomes complicated and it cannot be said that it is a simple method.

  In view of the above situation, the present invention provides a measuring method and apparatus for a measurement object using a variable natural vibration type cantilever capable of performing high-accuracy measurement by varying the natural frequency of the cantilever by a predetermined width. With the goal.

In order to achieve the above object, the present invention provides
[1] In a method for measuring an object to be measured by a natural vibration variable type cantilever, external energy is applied to the cantilever, and the natural frequency of the cantilever is made variable by a predetermined width, whereby the characteristic of the object to be measured is changed to that of the cantilever. Measured according to the natural frequency.

  [2] In the method for measuring an object to be measured by the natural vibration variable type cantilever described in [1] above, the cantilever is a nano-cantilever, the object to be measured is a minute substance, and the measurement is performed. To do.

  [3] In the method for measuring an object to be measured by the natural vibration variable type cantilever described in [1] or [2] above, vibration measurement is performed using a heterodyne laser Doppler meter in which the external energy is a light amount and has a light excitation function. In addition to the optical system that performs the above, there is a laser diode for optical excitation that superimposes constant light (DC component), and the natural frequency is obtained by superimposing the irradiation light from the laser diode on the laser that performs the vibration measurement. It is characterized by being variable.

  [4] In the method for measuring an object to be measured using the natural vibration variable type cantilever described in [1] or [2] above, vibration measurement is performed using a heterodyne laser Doppler meter in which the external energy is a light amount and has a light excitation function. In addition to the optical system that performs the above, there is a laser diode for optical excitation that superimposes constant light (DC component) and modulated light (AC component), and the irradiation light from this laser diode is superimposed on the laser that performs vibration measurement By doing so, the natural frequency is made variable.

  [5] In the method for measuring an object to be measured by the natural vibration variable type cantilever described in [1] or [2] above, the cantilever is positioned at a position avoiding the central axis in the longitudinal direction, the cantilever is bent, and The light is modulated with a frequency component corresponding to twist.

  [6] In the method for measuring an object to be measured by the natural vibration variable type cantilever described in [1] or [2] above, the amount of heat by irradiation light, which is different from the cantilever material on one side from the center line in the width direction of the cantilever. By providing a coating film having a high absorption rate, twisting of the cantilever is generated by irradiation light.

  [7] In the method of measuring an object to be measured by the natural vibration variable cantilever according to any one of [1] to [6], the cantilever is bent and twisted at a tip of the probe disposed at the tip of the cantilever. It is used to move along the Lissajous figure, thereby transferring and positioning the substance in contact with the tip of the probe.

  [8] In the method for measuring an object to be measured by the natural vibration variable type cantilever described in [7] above, the cantilever is bent and twisted, and modulated light having two frequency components of the natural frequency of bending and torsion is used. It is characterized by being performed by the light excitation used.

  [9] In the method for measuring an object to be measured by the natural vibration variable cantilever described in [8] above, the frequency of the torsion and the deflection is locked to an integer ratio using the frequency variable cantilever, and the cantilever of the cantilever is Changing the phase relationship between deflection and torsion, changing the rotational direction of movement along the Lissajous figure at the tip of the probe, and transferring and positioning the substance in contact with the tip of the probe in both directions in one degree of freedom. It is characterized by.

  [10] In the method of measuring an object to be measured by the natural vibration variable cantilever described in [8] above, the frequency of torsion and deflection is locked to an integer ratio using a frequency variable cantilever, and the cantilever of the cantilever is Changing the phase relationship between bending and twisting, including higher order modes, changing the rotational direction of movement along the Lissajous figure at the tip of the probe, and moving the material in contact with the tip of the probe in two directions with two degrees of freedom It is characterized in that it is transferred and positioned.

  [11] In the method for measuring an object to be measured by the natural vibration variable cantilever described in [8] above, the frequency of torsion and deflection is locked to an integer ratio using a frequency variable cantilever, and the cantilever of the cantilever is The phase relationship between bending and twisting is obtained by electrically changing two frequency components of the modulated light.

  [12] In the method for measuring an object to be measured by the natural vibration variable type cantilever described in [8] above, the frequency of the torsion and the deflection is locked to an integer ratio using the frequency variable type cantilever, and the cantilever of the cantilever is The phase relationship between bending and twisting is characterized in that the two frequency components of the modulated light are electrically changed to transfer and position the substance in contact with the probe tip in a plurality of directions.

  [13] In the method for measuring an object to be measured with the variable natural vibration cantilever according to [1] or [2], the external energy is a heat quantity.

  [14] In the method for measuring an object to be measured by the natural vibration variable type cantilever described in [1] above, the cantilever oscillating in the vicinity of the resonance point by an external oscillator is made to eliminate frequency change due to substance capture. Features.

  [15] In the method for measuring an object to be measured by the natural vibration variable type cantilever described in [1] above, the material capture of the cantilever is measured using a control amount for applying a heat amount for controlling the frequency change to zero. It is characterized by that.

  [16] In the method for measuring an object to be measured by the natural vibration variable type cantilever described in [1] above, the cantilever oscillating in the vicinity of the resonance point by an external oscillator has a frequency depending on the gradient of the force of the placed field. It is characterized by eliminating changes.

  [17] In the method of measuring an object to be measured by the natural vibration variable type cantilever described in [1] above, the solid measurement object and the cantilever are used by using a control amount for applying heat for controlling the frequency change to zero. The average distance from the fixed probe is controlled, and the force field on the surface of the solid sample is mapped at the atomic level.

  [18] In the method for measuring an object to be measured by the natural vibration variable type cantilever described in [1] above, a comb-shaped cantilever array is arranged, a resonance frequency of each cantilever is set, and thereby vibration measurement of each cantilever is performed at different frequencies. It is characterized by being performed by.

  [19] In a measuring device for a measurement object using a natural vibration variable type cantilever, by control of the natural frequency of the cantilever by control means for controlling the natural frequency of the cantilever to a predetermined width by adding external energy, And a means for measuring a characteristic of the measurement object.

  [20] The measuring device for a measuring object using the variable natural vibration cantilever according to [19] above, wherein the control means for the natural frequency of the cantilever is a light irradiation device for the cantilever.

  [21] In the measuring device for a measurement object using the natural vibration variable type cantilever according to [19], the cantilever is a nano-cantilever, the measurement object is a minute substance, and the measurement is performed. To do.

  [22] In the measuring device for a measurement object using the variable natural vibration cantilever according to [20], the light irradiation device is an optical system that performs vibration measurement using a heterodyne laser Doppler meter having a light excitation function. In addition, a laser diode for optical excitation that superimposes constant light (DC component) is provided.

  [23] In the measuring device for a measurement object using the variable natural vibration cantilever according to [20], the light irradiation device is an optical system that performs vibration measurement using a heterodyne laser Doppler meter having a light excitation function. In addition, a laser diode for optical excitation that superimposes constant light (DC component) and modulated light (AC component) is provided.

  [24] In the measuring device for a measuring object using the variable natural vibration cantilever according to [21], the control means for the natural frequency of the cantilever is a heating device for the cantilever.

  [25] In the measuring device for a measurement object using the natural vibration variable type cantilever described in [24] above, the heating device is a heating resistance wire disposed on a base of the cantilever.

  [26] In the measuring device for an object to be measured by the natural vibration variable type cantilever described in [25], the heating resistance wire is disposed in the vicinity of the base of the cantilever in the base of the cantilever. To do.

  [27] In the measuring device for a measurement object using the natural vibration variable type cantilever described in [19] above, the cantilever vibrating in the vicinity of the resonance point by the external oscillator is configured to eliminate the frequency change by capturing the substance. It is characterized by.

  [28] In the measuring device for a measuring object using the variable natural vibration cantilever according to [19], the material capture of the cantilever is measured using a control amount for applying a heat amount for controlling the frequency change to zero. It is characterized by comprising as follows.

  [29] In the measuring device for an object to be measured by the natural vibration variable type cantilever described in [19] above, the cantilever oscillating in the vicinity of the resonance point by an external oscillator has a frequency depending on the gradient of the force of the placed field. It is characterized by comprising so that a change may be eliminated.

  [30] In the measuring device for a measurement object using the natural vibration variable type cantilever described in [19] above, the solid measurement object and the cantilever are used by using a control amount for applying a heat amount for controlling the frequency change to zero. The average distance from the fixed probe is controlled, and the force field on the surface of the solid sample is mapped at the atomic level.

  [31] In the measuring device of a measurement object using the natural vibration variable type cantilever described in [19] above, a comb-shaped cantilever array is arranged, and a resonance frequency of each cantilever is set, whereby vibration measurement of each cantilever is performed at different frequencies. It is comprised so that it may be performed by.

According to the present invention, the following effects can be achieved.
(1) The natural frequency of the cantilever can be varied within a predetermined range, and highly accurate measurement can be performed.
(2) By using it as a vibration type micro actuator, the frequency of the torsion and deflection is locked to an integer ratio using a variable frequency cantilever, and the locus of the probe is changed by changing the phase of torsion and deflection. Can be changed to transfer and position the substance in contact with the probe tip.
(3) Utilizing the fact that the natural frequency of the cantilever can be varied within a predetermined range, mass change using a control amount that cancels frequency change due to mass addition to the cantilever and changes in the field where the cantilever is placed It is possible to measure the field precisely.

  That is, in a fixed-length cantilever, when a constant light is irradiated to the vicinity of the root, a phenomenon that the natural frequency is lowered due to a softening of the material or a dimensional increase due to a slight thermal expansion is found, and the modulated light and the constant light are simultaneously irradiated. By changing the amount of constant light, the natural frequency of the cantilever can be controlled, and the frequency at which resonance occurs can be controlled within a certain range. This method is not limited to light, and can be similarly realized by various heating methods such as Joule heat by energization and eddy current loss.

  When the natural frequency of the cantilever can be selected by light or current, various functions can be realized.

  Conventionally, the natural frequency of a cantilever is uniquely determined by its mechanical dimensions, but can be made substantially variable in real time with a certain width by the measuring device of the present invention. Further, it is possible to transfer and position the substance that contacts the tip of the probe.

  By irradiating the cantilever with light whose amount of light or heat is constant or modulated, its natural frequency is freely variable within a predetermined range. Thereby, the characteristics of the actuator can be changed, and the substance contacting the tip of the probe can be transferred and positioned.

  That is, the cantilever is optically irradiated with light to change the natural frequency.

  Further, the cantilever is provided with heating wiring, and the natural frequency is changed by energization heating.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 is a configuration diagram of a measuring apparatus for measuring an object using a variable oscillation nanocantilever according to an embodiment of the present invention. Here, a measuring apparatus having a light excitation function using a heterodyne laser Doppler meter will be described.

  As shown in this figure, the measurement apparatus includes an optical excitation unit 1, a signal processing unit 10, a laser Doppler interference unit 20, an AFM (atomic force microscope) sample stage 50, and a network analyzer 60.

  The optical excitation unit 1 includes a laser diode (LD) driver 2, a laser diode (LD) 3 driven by the LD driver 2, and a mirror 4.

  The signal processing unit 10 includes a first switch (sw1) 11, a second switch (sw2) 12, a digitizer 13, a phase shifter 14, a filter 15, and an amplifier 16.

  The laser Doppler interference unit 20 includes a He-Ne laser 21, a first PBS (polarizing beam splitter) 22, a second PBS 23, a multiplexer 24, a lens 25, a polarization plane preserving fiber 26, a sensor head (laser emitting unit). ) 27 (lens 27A-λ / 4 wavelength plate 27B-lens assembly 27C), nano-cantilever 28, [probe 28A, base 28B of nano-cantilever 28], mirror 29, AOM (acoustic light modulator) 30 , Λ / 2 wavelength plate 31, third PBS 32, polarizer 33, photodiode 34, BPF (band pass filter) 35, amplifiers 36, 38, 43, digitizers 37, 39, delay line 40, DBM (Double Balanced) Mixer (double balanced mixer) 41, LPF (low-pass filter) 2 consists of.

  Further, the AFM sample stage 50 includes a DBM 51 connected to an LO (local oscillator), a controller 52, a minute substance 53 as a sample, and a piezo element 54 of the sample 53.

  The network analyzer 60 has a signal input terminal 61 and an evaluation output terminal 62.

  Therefore, for example, the output light of the laser diode (LD) 3 having a wavelength of 780 nm is superimposed on the measurement light in the laser Doppler interference unit 20 of the He—Ne (helium-neon) laser 21 having a wavelength of 632 nm, Is introduced into a polarization-preserving fiber 26 having a 4 μm core, and irradiated through a laser emitting unit 27 and a nano-cantilever 28 to a minute substance 53 as a sample. However, the wavelength is not limited to the above.

  In this embodiment, in particular, as shown in FIG. 1, when the LD driver 2 generates a constant value signal (DC signal) and the LD 3 emits light with a light quantity determined by the value, the light is the nano-cantilever that is the object. As a result, the predetermined natural frequency of the nano-cantilever 28 changes.

  Further, when the LD driver 2 generates a signal (AC signal) that changes in a sine wave shape, and the LD 3 emits light whose amount of light is determined by the value, the cantilever 28 that is the object is irradiated accordingly, and the cantilever 28 is irradiated. 28 frequency changes are produced.

  Furthermore, when the amplification factor of the amplifier 16 is changed, the self-excited amplitude of the nano-cantilever 28 is changed, and the energy acting on the nano-cantilever 28 that is the object is also changed, so that the frequency of the nano-cantilever 28 is changed.

  In this way, the frequency of the nano-cantilever 28 is controlled by the AC signal component and the DC signal component, and the substance contacting the tip of the probe can be transferred and positioned.

  Moreover, the following measuring methods are possible using this measuring apparatus.

  (1) The output signal of the laser Doppler interfering unit 20 is phase-shifted, amplified, optionally filtered or binarized, and the laser diode 3 having a wavelength of 780 nm is modulated using the signal. Thereby, it becomes possible to generate self-excitation at the natural frequency of the minute substance 53 as the sample of the nanocantilever 28. That is, by selecting the filter characteristics, a specific vibration mode can be excited, and self-excitation of a substance as a sample of nanometer order to micron order can be realized.

  Further, by irradiating the nano-cantilever 28, which is a force detection element of the scanning probe microscope, with light, the nano-cantilever 28 is self-excited, and the probe 28A disposed at the tip of the nano-cantilever 28 due to the change in self-excitation frequency It becomes possible to detect the interaction and mass change of the minute substance 53 as a sample.

  In addition, by modulating the output light of the laser diode (LD) 3 having a wavelength of 780 nm, the natural frequency of the nano-cantilever 28 can be varied within a predetermined width, and the characteristics of the sample can be changed to the natural frequency of the nano-cantilever 28. It can be measured according to. The modulation method of the output light of the laser diode (LD) 3 includes direct modulation by adjusting the current applied to the laser diode (LD) 3, mechanical (mirror, prism, etc.) modulation in the optical system, thermal (refractive index change). Etc.) There is modulation.

  (2) A signal whose frequency is swept by the network analyzer 60 is generated, and the output light of the laser diode 3 having a wavelength of 780 nm is modulated using the signal.

  The output signal of the laser Doppler interference unit 20 is connected to the signal input terminal 61 of the network analyzer 60. As a result, it is possible to measure the frequency characteristics of the minute substance 53 as a sample using the network analyzer 60 and the laser Doppler interference unit 20 having the optical excitation function.

  Further, the light generated by the laser diode 3 for exciting the vibration of the nano-cantilever 28 is superimposed on the He—Ne laser (optical measurement probe light) 21 of the laser Doppler interference unit 20. At that time, the light for excitation is subjected to processing such as phase shift, binarization, amplification, etc. on the velocity signal output of the laser Doppler interference unit 20, and the light source such as the laser diode 3 is modulated using the signal. Or one modulated by the frequency specified by the transmitter or the swept frequency.

  In particular, in this embodiment, a laser diode 3 for optical excitation is provided separately from the optical system for vibration measurement.

  Here, as an example, a heterodyne laser Doppler meter having an optical excitation function and a variable frequency is shown. It is possible to change the frequency by giving the optical excitation laser a DC offset.

  That is, in this embodiment, a heterodyne laser Doppler meter having an optical excitation function has a laser diode for optical excitation separately from an optical system for vibration measurement. This laser diode is normally used for light excitation after luminance modulation, but when constant light (DC component) is superimposed, the natural frequency can be changed by the luminance.

  An example of the result is shown in FIG.

  FIG. 2 is a characteristic diagram of resonance frequency (Hz) with respect to optical power (mW) by irradiation of a light beam to the cantilever. FIG. 2A shows the resonance frequency (Hz) of bending of the cantilever, and FIG. The resonance frequency (Hz) of torsion of the cantilever is shown.

  In FIG. 2, the cantilever is vibrated by a piezo element, and the vibration of the heterodyne laser Doppler meter is measured and the light from the laser diode (LD) 3 is irradiated.

  As shown in FIG. 2, when the optical power (mW) of the laser diode (LD) 3 is changed, the resonance frequency can be changed.

  Therefore, by changing the resonance frequency of the nano-cantilever 28 that measures a substance as a sample, the physical characteristics of the substance can be measured with high accuracy.

  As described above, the case where the natural frequency of the nanocantilever is changed by irradiating the nanocantilever with light has been described so far. In order to simplify the configuration, the natural frequency of the cantilever is changed by heating the cantilever. You may make it make it.

  Even if 780 nm light having a large silicon transmission amount and poor efficiency is used, a frequency variable range of about 200 Hz is secured at 1.6 mW. In the case of 405 nm light, it is possible to confirm a frequency lockable range of about 1 kHz with a laser beam of about 2 mW and a frequency lockable range of about 10 kHz with a 405 nm and 30 mW laser that are readily available.

  FIG. 3 is an explanatory diagram of excitation light that imparts torsion and deflection to a plurality of nanocantilevers of the present invention.

  In this figure, reference numeral 71 is a common base of nano-cantilevers, 72 is a nano-cantilever, 73 is a probe, 74 is a sample stage, and 75 is excitation light (excitation light having an AC signal component) that generates torsion and deflection to the nano-cantilever 72. ), 76 is excitation light (excitation light having a DC signal component) that locks the frequency of twisting and bending to an integer ratio and changes the phase difference, and is superimposed on the excitation light 75.

  FIG. 4 is a plan view showing an example in which light is irradiated to a position deviated from the center line of the nano cantilever in order to give twist and deflection to the nano cantilever of the present invention, and FIG. 5 is a diagram showing the excitation result. .

  In FIG. 4, 81 is a nano-cantilever, 82 is a center line of the nano-cantilever 81, 83 is an irradiation light position, and 84 is a detection position.

  Therefore, when the irradiation light position 83 is irradiated with irradiation light having a component with a frequency of 303.1 kHz to excite the nanocantilever 81, the detection position 84 is bent at a frequency of 303.1 kHz as seen at the peak 86. A primary vibration mode was generated. Further, when the irradiation light position 83 is irradiated with irradiation light having a component having a frequency of 1.914 MHz and the nanocantilever 81 is excited, the detection position 84 is twisted at a frequency of 1.914 MHz as seen at the peak 88. A primary vibration mode was generated. When the irradiation light position 83 is irradiated with light having other unique frequencies, as can be seen from the peaks 87 and 89, the higher-order modes (twisted secondary vibration mode and torsional secondary vibration mode) of the torsion and the bending are cantilever 81. Was generated.

  The state of twisting and bending of the nanocantilever is shown in FIGS.

  In FIG. 6, 91 is a nano-cantilever, and 92 is a probe disposed at the tip of the nano-cantilever 91. When the direction of bending A is the z-axis and the direction of torsion B is the x-axis, the tip of the probe 92 is , Shown as movements 93 and 94 along the Lissajous figure in the xz plane, and is bidirectional. FIG. 6 shows a case where the frequencies of twisting and bending match.

  In FIG. 7, 95 is a nano-cantilever, and 96 is a probe disposed at the tip of the nano-cantilever 95. If the direction of the bending primary C is the z-axis and the direction of the bending high-order D is the y-axis, The tip of the probe 96 is shown as a movement 97 along the Lissajous figure in the yz plane. FIG. 7 shows a case where the torsional and bending frequencies coincide.

  In this way, when performing optical excitation of one (or many) nanocantilevers, the excitation light applied to the nanocantilevers is positioned away from the central axis in the longitudinal direction of the nanocantilevers, for example, the longitudinal direction of the nanocantilevers As shown in FIG. 6, the tip of the probe 92 arranged at the tip of the nano-cantilever 91 is positioned in the xz plane. Exercise 93, 94 along the Lissajous figure. At that time, if the phase relationship between the two frequency components of the light excitation by the modulated light is electrically changed, and thereby the phase relationship between the two frequency components of the modulated light is changed, the phase relationship between the deflection and the twist of the nanocantilever 91 changes. As a result, it is possible to create a state in which the movements 93 and 94 along the Lissajous figure are clockwise or counterclockwise as viewed from the y-axis. Thereby, it is possible to transfer and position an object that contacts the tip of the probe 92 in the positive and negative directions in the x-axis direction.

  Further, as shown in FIG. 7, in the optical excitation of one (or many) cantilevers 95, it is possible to excite higher-order modes of torsion and deflection of the cantilevers.

  In particular, when a higher-order mode of bending is generated, the tip of the probe 96 becomes a movement 97 along the Lissajous figure in the yz plane, and the object contacting the tip of the probe 96 can be transferred and positioned in the y direction. It is. Also in this case, the phase relationship between bending and twisting is changed electrically or by changing the natural frequency due to light, and the object contacting the tip of the probe 96 is transferred and positioned in the positive and negative directions in the y-axis direction. It is possible.

  By using the first and higher modes of bending and twisting simultaneously or independently, it is possible to move and position an object contacting the probe tip in the positive and negative directions in the x and y axes. is there. In this case as well, a method of electrically changing the rotational direction of the motion along the Lissajous figure and a natural frequency is changed by light or heat (described later), resulting in a change of the rotational direction of the motion along the Lissajous figure. It is possible to make it.

  As described above, if the method of changing the natural frequency by light is used, it is possible to make the natural frequency of the cantilever variable for measurement using the resonance phenomenon with the sample and improve the sensitivity of measurement. . In addition, taking advantage of the fact that the frequency of the cantilever is variable, the frequency ratio of the torsional and bending modes is locked by control, and the mutual phase relationship is changed, whereby the movement of the tip of the probe can be controlled. It is possible to move and position the object in contact with the probe tip in the positive and negative directions in the x-axis and y-axis direction by changing the direction of movement along the Lissajous figure at the tip of the probe. is there.

  FIG. 8 is a schematic diagram of a nano-cantilever in which a coating film having a high heat absorption rate by irradiation light different from the cantilever material is provided on one side of the center line in the width direction of the nano-cantilever to twist the nano-cantilever of the present invention. It is.

  In this figure, reference numeral 98 denotes a nanocantilever, and 99 denotes a coating film provided on one side of the nanocantilever 98, which is different from the nanocantilever material and has a high heat absorption rate by irradiation light. For example, when the nano-cantilever material is silicon, a coating 99 such as Au or Al is provided.

  In this way, when the entire nanocantilever 98 is irradiated with irradiation light, the heat absorption rate of the coating 99 is higher than that of the portion without the coating 99, and the nanocantilever 98 is intended to bend and twist. It can be generated in phase.

  FIG. 9 is a configuration diagram of a measuring object measuring apparatus using a natural vibration variable nano-cantilever using heat generated by energization according to an embodiment of the present invention, and FIG. 9A is a top view thereof, FIG. (B) is the side view.

  In these figures, 101 is a nano-cantilever, 102 is a base of the nano-cantilever 101, 104 is a wiring having a heating wire (resistance wire) 103 arranged in the base 102 of the nano-cantilever, 105 and 106 are the wiring 104 Electrode.

  As described above, since the resistance wire 103 for energization heating is arranged in the vicinity of the cantilever base 101A of the cantilever base 102, the natural frequency of the cantilever 101 can be changed by energization heating.

  Next, an example in which a cantilever is used as a voltage controlled oscillator (VCXO) will be described.

  When mass detection is performed using a cantilever, a change in frequency with mass addition is usually measured. However, when measuring with a narrow band and high resolution, a circuit with an electrically sharp and narrow filter characteristic is used. Therefore, when the frequency changes, the signal level is drastically reduced due to deviation from the signal pass band of the circuit. There was a problem that it became difficult. In response to this problem, when the natural frequency of the cantilever is controlled by applying heat to the cantilever, the mass can be added while controlling the vibration frequency of the cantilever so that the frequency does not change. Can be detected with high resolution. Details will be described below.

  FIG. 10 is a configuration diagram of a measuring device for a measuring object using a variable natural vibration cantilever according to an embodiment of the present invention. Here, a measuring device having a light excitation function using a heterodyne laser Doppler meter will be described.

  As shown in this figure, this measuring apparatus includes a cantilever 201, a base 202 of the cantilever 201, a He-Ne laser 203, mirrors 204 and 206, PBS 205, 208 and 210, and an AOM (207 Acousto-optic modulator), 209 and 211 are λ / 4 wavelength plates, 212, 229 and 230 are lenses, 213 are photodiodes, 214 are band pass filters, 215 are delay lines, 216 and 219 are DBMs, 217 and 220 are Low-pass filter, 218 is a phase shift circuit, 221 is a VCO (voltage controlled oscillator), 222 is an integration circuit for obtaining an integral term gain, 223 is a proportional circuit for obtaining a gain P1 (proportional term gain), and 224 is self-excited Selection switch 225 for selecting either the AC signal 1 for self-use or the AC signal 2 for self-excitation, and 225 a gain P2 (proportional term In), a proportional circuit 227, an output signal from the proportional circuit 225, a constant frequency holding control signal which is an output signal from a parallel circuit of the integrating circuit 222 and the proportional circuit 223, and a reference voltage generator 226 228 is a laser diode for irradiating the excitation AC light of the cantilever 201 and DC light for softening the cantilever 201 and lowering the frequency of the cantilever 201.

  In this way, the cantilever 201, the excitation AC light of the cantilever 201, the laser diode 228 for irradiating the cantilever 201 with DC light for softening the cantilever 201 and reducing the frequency of the cantilever 201, A heterodyne laser Doppler meter is provided for measurement. The velocity signal of the cantilever 201 that is the output of the heterodyne laser Doppler meter is detected by the photodiode 213 and obtained through the low-pass filter 217, and the self-excited AC signal 1 is obtained by the phase shift circuit 218. By using the AC signal 1 as a drive signal for the laser diode 228, self-excitation of the cantilever 201 is generated by using a gain P2 larger than a certain value.

  A speed signal of the heterodyne laser Doppler meter and a VCO (voltage controlled oscillator) 221 are input to the DBM 219, and an output thereof is input to the VCO 221 via the low-pass filter 220. The cantilever 201 can be self-excited by using a larger gain P2. Note that either the self-exciting AC signal 1 or the self-exciting AC signal 2 is selected and used by the selection switch 224. The input of the VCO 221 includes information on a difference in a relatively short time from the vibration frequency so far, and corresponds to a mass change added to the cantilever 201. If the difference amount is plotted on the horizontal axis and the frequency of occurrence thereof is plotted on the vertical axis, the distribution of elementary masses of various masses added to the cantilever 201 can be measured. This is a mass spectrometer using a cantilever.

  In this configuration, the frequency change null method is applied to the so-called “Q control method” by keeping the gain P2 smaller than a certain threshold value.

The reference signal V _O from the reference signal generator 226 is for irradiating the cantilever 201 with a predetermined amount of light in advance, and the effect can be canceled when the frequency of the cantilever 201 changes to high or low. The offset light quantity is set as follows.

  In this way, when a cantilever is irradiated with a certain amount of light and intensity-modulated light and a frequency drop due to mass addition occurs, the change is electrically detected from comparison with the reference frequency, and based on the signal The constant light quantity is weakened so that the frequency is increased, and the cantilever is hardened to maintain the constant frequency. This is a null control that keeps the frequency change to zero, and is a method for detecting a highly sensitive change by making use of extremely sharp filter characteristics and cantilever resonance characteristics. Here, the signal before the parallel circuit of the integration circuit 222 and the proportional circuit 223 in FIG. 10 corresponds to the instantaneous mass change amount, and the output of the parallel circuit of the integration circuit 222 and the proportional circuit 223 corresponds to the total mass change. To do. Therefore, if the difference in mass change is plotted on the horizontal axis and the cumulative occurrence frequency is plotted on the vertical axis, the frequency of mass added to the cantilever can be found. For example, a graph can be obtained in which A Dalton particles are added 100 times and B Dalton particles are added 2000 times. Thereby, the mass spectrometer (mass spectrometer) using the cantilever shown in FIG. 10 is realizable.

  FIG. 11 is a diagram showing an independent measurement mode for each high-precision cantilever by giving a gradient to DC light when the cantilevers according to the embodiment of the present invention are arranged in an array. The frequency and the amplitude corresponding to are shown.

  In FIG. 11, 301 is a base of a cantilever, 302 is a cantilever arranged in an array arranged on the base 301, 303 indicates DC light, and the DC light intensity decreases from the left side to the right side. Yes.

  When the cantilevers 302 are arranged in an array like this, there is usually a problem that if the frequencies are close to each other, vibrations are coupled and it becomes difficult to perform independent measurement for each cantilever. In response to this problem, by irradiating the DC light 303 having a gradient of position in intensity, the frequency of the cantilever 302 irradiated with the high intensity DC light 303 is low, and vice versa. The cantilever array can have a frequency gradient. As a result, the problem of coupling is eliminated, and the measurement separated by frequency becomes possible.

  FIG. 12 is a configuration diagram of a measuring apparatus that performs AFM imaging by displacing a sample stage up and down using a constant frequency holding signal according to an embodiment of the present invention. Here, too, a heterodyne laser Doppler meter has an optical excitation function. A measuring apparatus having the following will be described.

As shown in this figure, this measuring apparatus has a cantilever 401, a base 402 of the cantilever, a 403 He-Ne laser, 404 and 406 mirrors, 405, 408 and 410 PBS, and 407 AOM (acoustic sound). 409, 411 are λ / 4 wave plates, 412, 429, 430 are lenses, 413 is a photodiode, 414 is a band pass filter, 415 is a delay line, 416, 419 are DBM, 417, 420 are low pass. Filter, 418 is a phase shift circuit, 421 is a VCO (voltage controlled oscillator), 422 is an integration circuit for obtaining an integral term gain I ₁ , 423 is a proportional circuit for obtaining a gain P1 (proportional term gain), 424 is its own A selection switch 425 for selecting either the excitation AC signal 1 or the self-excitation AC signal 2 has a gain P2 (proportional term gain). 427 is an output signal from the proportional circuit 425, a constant frequency holding control signal which is an output signal from a parallel circuit of the integrating circuit 422 and the proportional circuit 423, and a reference voltage generator 426. 428 is a laser diode for irradiating AC light for exciting the cantilever 401 and DC light for softening the cantilever 401 and lowering the frequency of the cantilever 401, The cantilever 401 to the lens 430 have the same configuration and function as the cantilever 201 to the lens 230 in FIG. 10 described above. In this embodiment, the cantilever 401 further includes a probe 505. The cantilever 401 has a base 402 having a fixing portion 502, and the fixing portion 502 is a base. And it is fixed to 01. A piezo element (sample stage) 503 is disposed on the base 501, and the sample 504 is set on the piezo element 503. In this piezo element 503, the constant frequency holding control signal, which is the output signal of the proportional integral control circuits 222 and 223, obtains the integration circuit 506 for obtaining the integral term gain I ₂ and the gain P3 (proportional term gain). Therefore, a signal through a parallel circuit with the proportional circuit 507 is applied. In other words, an AFM imaging function is added, and the sample stage made up of the piezo element 503 can be moved up and down using the constant frequency holding control signal. As a result, it is possible to perform imaging at the atomic level with a narrow band, low noise, and no frequency shift, and it is possible to apply not only in an ultra-high vacuum atmosphere but also in an atmosphere in air or liquid.

  Further, if the torsional and flexural vibrations of the cantilever are generated simultaneously, the tip of the probe fixed to the cantilever tip vibrates along a certain locus. Here, if the relative phase of the torsional vibration and the bending vibration can be changed, the object with which the probe contacts can be moved in both directions in the direction perpendicular to the longitudinal direction of the cantilever. The method of controlling the frequency by applying heat to the cantilever of the present invention can be used to produce this phase difference. Further, by using a plurality of modes of bending of the cantilever and the phase relationship thereof, it is possible to move the object in contact with the tip of the probe bidirectionally in the longitudinal direction of the cantilever.

  In addition, this invention is not limited to the said Example, Based on the meaning of this invention, a various deformation | transformation is possible and these are not excluded from the scope of the present invention.

  The method and apparatus for measuring a measurement object using a natural vibration variable type cantilever according to the present invention is suitable for measuring a measurement object using a natural vibration variable type nano cantilever that measures a characteristic of a highly accurate substance.

It is a block diagram of the measuring apparatus of the measuring object by the natural vibration variable type nano cantilever using the light which shows the Example of this invention. It is a resonance frequency characteristic figure with respect to the optical power by irradiation of the light beam to the nano cantilever by the Example of this invention. It is explanatory drawing of the excitation light which gives a twist and bending to the some nano cantilever of this invention. It is a top view which shows the example which irradiates and excites light to the position which deviated from the centerline of the nano cantilever in order to give twist and bending to the nano cantilever of this invention. It is a figure which shows the excitation result shown by FIG. It is explanatory drawing (the 1) of the twist and bending of the nano cantilever by this invention. It is explanatory drawing (the 2) of the twist and bending of the nano cantilever by this invention. FIG. 2 is a schematic diagram of a nanocantilever in which a coating film having a high heat absorption rate by irradiation light is provided on one side in the width direction of the nanocantilever in order to give a twist to the nanocantilever of the present invention, unlike a cantilever material. It is a block diagram of the measuring apparatus of the measuring object by the natural vibration variable type nano cantilever using the heat which generate | occur | produces by electricity supply which shows the Example of this invention. It is a block diagram of the measuring device of the measuring object by the natural vibration variable type cantilever which shows the Example of this invention. It is a figure which shows the independent measurement aspect for every high precision cantilever which gives the gradient to DC light in case the cantilevers which show the Example of this invention are located in an array form. It is a block diagram of the measuring device which displaces a sample stand up and down using the signal for constant frequency holding which shows the Example of this invention, and performs AFM imaging.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical excitation part 2 Laser diode (LD) driver 3,228,428 Laser diode (LD)
4, 29, 204, 206, 404, 406 Mirror 10 Signal processor 11 First switch (sw1)
12 Second switch (sw2)
13, 37, 39 Digitizer 14 Phase shifter 15 Filter 16 Amplifier 20 Laser Doppler interference unit 21, 203, 403 He-Ne laser 22 First PBS (Polarizing beam splitter)
23 Second PBS
24 multiplexer 25, 27A, 212, 229, 230, 412, 429, 430 lens 26 polarization plane preserving fiber 27 sensor head (laser emitting section)
27B, 209, 211, 409, 411 λ / 4 wavelength plate 27C Lens assembly 28, 72, 81, 91, 95, 98, 101, 201, 401 Nano cantilever 28A, 73, 92, 96 Probe (probe)
28B, 102, 202, 301, 402 Nanocantilever base 30,207,407 AOM (acoustic light modulator)
31 λ / 2 wave plate 32 3rd PBS
33 Polarizer 34, 213, 413 Photodiode 35, 214, 414 BPF (band pass filter)
36, 38, 43 Amplifier 40, 215, 415 Delay line 41, 51, 216, 219, 416, 419 DBM
42, 217, 220, 417, 420 LPF (low pass filter)
50 AFM (Atomic Force Microscope) Sample Stage 52 Controller 53 Micro Material as Sample 54 Piezo Element 60 Network Analyzer 61 Signal Input Terminal 62 Evaluation Output Terminal 71 Common Base of Nanocantilever 74 Sample Stand 75 Excitation Light that Generates Twist and Deflection 76 Excitation light that changes the phase difference between torsion and deflection 82 Nanocantilever center line 83 Irradiation light position 84 Detection position 86 Deflection primary vibration mode 87 Deflection secondary vibration mode 88 Torsion primary vibration mode 89 Torsion secondary vibration mode 93 , 94, 97 Movement along Lissajous figure 99 Coating 101A Nanocantilever base 103 Heating wire (resistance wire)
104 Wiring 105, 106 Electrode 205, 208, 210, 405, 408, 410 PBS
218, 418 Phase shift circuit 221, 421 VCO (voltage controlled oscillator)
222, 422 Integration circuit for obtaining integral term gain 223, 423 Proportional circuit for obtaining gain P1 (proportional term gain) 224, 424 Selection switch 225, 425 Proportional circuit for obtaining gain P2 (proportional term gain) 226 , 426 Reference voltage generator 227, 427 Adder 302 Cantilever arranged in an array arranged on the base 303 DC light 505 Cantilever probe 501 Base 502 Cantilever base fixing part 503 Piezo element (sample stand)
504 Sample 506 Integration circuit for obtaining integral term gain I ₂ 507 Proportional circuit for obtaining gain P3 (proportional term gain)

Claims (31)

  A variable natural vibration type characterized in that the characteristic of a measurement object is measured corresponding to the natural frequency of the cantilever by applying external energy to the cantilever and making the natural frequency of the cantilever variable within a predetermined width. Method for measuring objects using cantilevers.   2. The method for measuring an object to be measured by a natural vibration variable type cantilever according to claim 1, wherein the cantilever is a nano-cantilever, the measurement object is a minute substance, and the measurement is performed. Measuring method of objects to be measured with mold cantilevers.   3. An optical system for measuring vibration using a heterodyne laser Doppler meter having a photoexcitation function, wherein the external energy is a light amount in the method for measuring an object to be measured using the variable natural vibration cantilever according to claim 1 or 2. In addition, it has a laser diode for optical excitation that superimposes constant light (DC component), and the natural frequency is made variable by superimposing irradiation light from the laser diode on the laser that performs vibration measurement. The measuring method of the measuring object by the natural vibration variable type cantilever.   3. An optical system for measuring vibration using a heterodyne laser Doppler meter having a photoexcitation function, wherein the external energy is a light quantity, and the measuring method of the measuring object using the variable natural vibration cantilever according to claim 1 or 2. Separately, it has a laser diode for optical excitation that superimposes constant light (DC component) and modulated light (AC component), and the natural frequency is obtained by superimposing irradiation light from the laser diode on the laser that performs vibration measurement. A method for measuring an object to be measured by a natural vibration variable type cantilever characterized by making the variable.   3. The method of measuring an object to be measured by the natural vibration variable type cantilever according to claim 1 or 2, wherein a light spot is positioned at a position avoiding a central axis in a longitudinal direction of the cantilever, and corresponds to bending and twisting of the cantilever. A method for measuring an object to be measured by a variable natural vibration cantilever, wherein light is modulated with a frequency component to be transmitted.   3. A method for measuring an object to be measured by a natural vibration variable type cantilever according to claim 1 or 2, wherein the coating film has a high heat absorption rate by irradiation light, which is different from the cantilever material on one side of the center line in the width direction of the cantilever. The torsion of the cantilever is generated by the irradiation light by providing a measuring method of the measuring object using the variable natural vibration type cantilever.   In the measuring method of the measuring object by the natural vibration variable type cantilever according to any one of claims 1 to 6, along the Lissajous figure using the bending and twisting of the cantilever at the tip of the probe arranged at the tip of the cantilever. A method of measuring an object to be measured by a variable natural vibration cantilever, wherein a material that contacts the tip of the probe is transferred and positioned accordingly.   8. The method of measuring an object to be measured with a variable natural vibration type cantilever according to claim 7, wherein the cantilever is bent and twisted by optical excitation using modulated light having two frequency components of the natural frequency of bending and twisting. The measuring method of the measuring object by the natural vibration variable type cantilever characterized by performing by the above.   In the method of measuring an object to be measured by the natural vibration variable type cantilever according to claim 8, the frequency of torsion and deflection is locked to an integer ratio, the phase relationship between the deflection and torsion of the cantilever is changed, and Measurement with a variable natural vibration cantilever characterized by changing the rotational direction of movement along the Lissajous figure at the tip of the probe, and transferring and positioning the substance in contact with the tip of the probe in both directions in one degree of freedom. Measurement method of the object.   9. The method of measuring an object to be measured by a natural vibration variable type cantilever according to claim 8, wherein the torsion and deflection frequencies are locked to an integer ratio, and the phase relationship between the cantilever deflection and torsion is set to a higher order mode. The rotation direction of the movement along the Lissajous figure at the tip of the probe is changed, and the material contacting the tip of the probe is transferred and positioned in both directions in two degrees of freedom. A method for measuring an object using a variable natural vibration cantilever.   9. The method of measuring an object to be measured by a natural vibration variable type cantilever according to claim 8, wherein the torsion and deflection frequencies are locked to an integer ratio, and the phase relationship between the cantilever deflection and torsion is expressed by the modulated light. A method for measuring an object to be measured by a natural vibration variable type cantilever obtained by electrically changing two frequency components.   9. The method of measuring an object to be measured by a natural vibration variable type cantilever according to claim 8, wherein the torsion and deflection frequencies are locked to an integer ratio, and the phase relationship between the cantilever deflection and torsion is expressed by the modulated light. A method of measuring an object to be measured by a variable natural vibration cantilever, wherein two frequency components are electrically changed, and a substance in contact with the probe tip is transferred and positioned in a plurality of directions.   3. The measuring method of a measuring object using a variable natural vibration cantilever according to claim 1 or 2, wherein the external energy is a heat quantity.   2. The method of measuring an object to be measured by a natural vibration variable type cantilever according to claim 1, wherein the cantilever oscillating in the vicinity of the resonance point by an external oscillator eliminates a frequency change by trapping the substance. A measuring method of a measurement object using a vibration-variable cantilever.   2. The method of measuring an object to be measured by a natural vibration variable type cantilever according to claim 1, wherein the material capture of the cantilever is measured using a control amount for applying a heat amount for controlling the frequency change to zero. Measuring method of measuring object using natural vibration variable cantilever.   2. The measuring method of an object to be measured by a natural vibration variable type cantilever according to claim 1, wherein the cantilever vibrating in the vicinity of the resonance point by the external oscillator eliminates the frequency change due to the gradient of the force of the placed field. A method for measuring an object to be measured by a natural vibration variable type cantilever characterized by comprising:   2. A method of measuring a measurement object using a variable natural vibration type cantilever according to claim 1, wherein the probe is fixed to the solid measurement object and the cantilever using a control amount for applying a heat amount for controlling the frequency change to zero. A method for measuring a measurement object using a variable natural vibration type cantilever, wherein the force field on the surface of a solid sample is mapped at an atomic level by controlling an average distance from the surface.   The method for measuring an object to be measured by a natural vibration variable type cantilever according to claim 1, wherein a comb-shaped cantilever array is arranged, a resonance frequency of each cantilever is set, and thereby vibration measurement of each cantilever is performed at a different frequency. A measuring method of an object to be measured with a characteristic natural vibration cantilever. (A) control means for controlling the natural frequency of the cantilever to a predetermined width by adding energy from the outside;
(B) An apparatus for measuring a measurement object using a variable natural vibration cantilever, comprising means for measuring the characteristic of the measurement object by controlling the natural frequency of the cantilever.   20. The measuring device for a measuring object using a variable natural vibration cantilever according to claim 19, wherein the control means for the natural frequency of the cantilever is a light irradiation device for the cantilever. Measuring device for measuring objects.   20. The measuring apparatus for a measurement object using a natural vibration variable type cantilever according to claim 19, wherein the cantilever is a nano-cantilever, the measurement object is a minute substance, and the measurement is performed. Measuring device for measuring objects using a cantilever of a mold.   21. The apparatus for measuring an object using a variable natural vibration type cantilever according to claim 20, wherein the light irradiation device is a constant light beam separately from an optical system that performs vibration measurement using a heterodyne laser Doppler meter having a light excitation function. An apparatus for measuring an object to be measured by a natural vibration variable type cantilever, comprising a laser diode for optical excitation on which (DC component) is superimposed.   21. The apparatus for measuring an object using a variable natural vibration type cantilever according to claim 20, wherein the light irradiation device is a constant light beam separately from an optical system that performs vibration measurement using a heterodyne laser Doppler meter having a light excitation function. An apparatus for measuring an object to be measured by a natural vibration variable type cantilever comprising a laser diode for optical excitation that superimposes (DC component) and modulated light (AC component).   23. The measuring device for a measuring object using a natural vibration variable cantilever according to claim 21, wherein the control means for the natural frequency of the cantilever is a heating device for the cantilever. Measuring device for measuring objects.   25. The measuring device of a measurement object using a variable natural vibration cantilever according to claim 24, wherein the heating device is a heating resistance wire disposed on a base of the cantilever. Measuring device for measuring objects.   26. The measuring apparatus of a measuring object using a variable natural vibration cantilever according to claim 25, wherein the heating resistance wire is disposed in the vicinity of the base of the cantilever in the base of the cantilever. Measuring device for measuring objects using a cantilever of a mold.   20. The measuring device for a measuring object using a natural vibration variable type cantilever according to claim 19, wherein the cantilever oscillating in the vicinity of the resonance point by an external oscillator is configured to eliminate frequency change by substance trapping. A measuring device for measuring objects using a variable natural vibration cantilever.   20. The measuring device for an object to be measured by the natural vibration variable type cantilever according to claim 19, wherein the material capture of the cantilever is measured using a control amount for applying a heat amount for controlling the frequency change to zero. An apparatus for measuring an object to be measured by a natural vibration variable type cantilever.   20. The measuring device for a measuring object using a variable natural vibration cantilever according to claim 19, wherein the cantilever vibrating in the vicinity of the resonance point by an external oscillator eliminates the frequency change due to the gradient of the force of the placed field. An apparatus for measuring an object to be measured by a natural vibration variable type cantilever.   20. The measuring device for a measuring object using a variable natural vibration cantilever according to claim 19, wherein the probe is fixed to the solid measuring object and the cantilever using a control amount for applying a heat amount for controlling the frequency change to zero. The device for measuring a measuring object using a variable natural vibration cantilever characterized in that the average distance to the surface is controlled and the force field on the surface of the solid sample is mapped at the atomic level.   20. The measuring device for a measuring object using a variable natural vibration cantilever according to claim 19, wherein a comb-shaped cantilever array is arranged, and a resonance frequency of each cantilever is set, whereby vibration measurement of each cantilever is performed at a different frequency. An apparatus for measuring an object to be measured by a natural vibration variable type cantilever characterized by comprising.

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