CN102538657B - Three-dimensional resonance trigger measuring head based on PVDF (polyvinylidene fluoride) and three-dimensional resonance trigger positioning method - Google Patents

Abstract

The invention discloses a PVDF-based three-dimensional resonance trigger measuring head and a three-dimensional resonance trigger positioning method. The outer side of a piezoelectric driver with the same structure, the inner side of the piezoelectric driver is symmetrically fixed on both sides of the T-shaped probe frame, and the integrated micro-rod probe is fixed at the central position of the lower surface of the piezoelectric film; The AC signal is applied to the piezoelectric driver as an excitation signal to drive the piezoelectric film to drive the integrated micro-rod probe to work in a resonant state; the integrated micro-probe probe driven by the piezoelectric film is set to perform Z-direction on the surface of the sample. The test is in the tapping mode; the X-direction and Y-direction tests on the side of the sample are in the friction mode; the change of the differential charge signal on the polarized surface of the PVDF piezoelectric film is detected to characterize the contact between the integrated micro-probe probe and the sample degree of touch. The invention can be applied to three-dimensional shape measurement of various high-precision, micro-measurement force soft materials, micro devices, ultra-precision optical devices and the like.

Description

Three-dimensional resonance trigger probe and three-dimensional resonance trigger positioning method based on PVDF

technical field

The invention relates to a three-dimensional resonance trigger probe and a three-dimensional resonance trigger positioning method that can be applied in the field of three-dimensional shape measurement of various high-precision, micro-measurement force soft materials, micro-mechanical parts, micro-devices, ultra-precision optical devices, etc. .

Background technique

In recent years, the development of nano-positioning technology has brought ultra-finishing and ultra-micro-machining into a new era of nanotechnology, enabling the measurement of small displacements and small objects to reach nanometer and sub-nanometer levels. (CMM), especially the micro-nano probe, puts forward higher requirements such as high precision and low measurement force. At present, there is no mature technology to meet the demand.

Existing micro-nano CMM probes generally include contact probes and non-contact probes. The contact probe is in direct contact with the sample, and the three-dimensional shape information is obtained by collecting and processing the three-dimensional coordinates of the surface contour points of the sample; the non-contact probe is generally based on the optical principle and equipped with optical path design to obtain the surface topography data. The contact probe has good reliability and high precision, but the measuring force generated when the probe contacts the surface of the sample may cause elastic or even plastic deformation, especially soft materials cannot be measured. The non-contact probe avoids the influence of contact force, and has high measurement speed and sampling frequency, but it is greatly affected by the characteristics of the object surface, and cannot reach the resolution and uncertainty of the contact probe.

Contents of the invention

In order to avoid the shortcomings of the above-mentioned prior art, the present invention provides a PVDF-based three-dimensional resonance trigger probe and a three-dimensional resonance trigger positioning method. Sensitivity, combined with the integrated micro-rod probe, constitutes a micro-force three-dimensional resonance trigger probe, which is used to realize high-precision, low-measurement force three-dimensional resonance trigger measurement and position.

The present invention adopts the following technical solutions for solving technical problems:

The structural characteristics of the PVDF-based three-dimensional resonant trigger measuring head of the present invention are as follows: the PVDF piezoelectric film is used as a vibrating beam with a simply supported beam structure, and the left and right ends of the PVDF piezoelectric film are respectively fixed on two piezoelectric plates with the same structure. The outer side of the electric driver, the inner side of the two piezoelectric drivers of the same structure are symmetrically fixed on both sides of the T-shaped probe frame, and an integrated micro-probe is fixed at the central position of the lower surface of the PVDF piezoelectric film Probe;

A sinusoidal AC signal is applied to the piezoelectric driver as an excitation signal to drive the PVDF piezoelectric film to drive the integrated micro-rod probe to work in a resonance state;

Setting the integrated micro-rod probe driven by the PVDF piezoelectric film on the surface of the sample to perform the Z-direction test is a tapping mode; setting the integrated micro-probe probe driven by the PVDF piezoelectric film in the The side of the sample is tested in the X direction and Y direction as the friction mode; the change of the differential charge signal on the polarized surface of the PVDF piezoelectric film is detected to characterize the contact degree between the integrated micro-probe probe and the sample .

The characteristics of the three-dimensional resonance triggering positioning method of the PVDF-based three-dimensional resonance triggering probe in the present invention are that the three-dimensional resonance triggering probe remains stationary, and the translation of the sample in the horizontal plane completes the positioning of the three-dimensional resonance triggering probe on the surface of the sample. Three-dimensional trigger positioning; or the sample remains still, and the translation of the probe in the horizontal plane is triggered by three-dimensional resonance to complete its three-dimensional trigger positioning on the sample surface.

The invention utilizes the piezoelectric characteristics, high resonance characteristics and high sensitivity to tiny forces of PVDF film, and combines with the integrated micro-rod measuring head to construct a PVDF vibrating beam-type micro-probing system, and drives the measuring head to reach a resonance state through a driving signal. The signal processing circuit detects and processes the electrical signal generated by the polarized surface of the PVDF piezoelectric film and compares it with the set voltage value to realize amplitude feedback and realize the measurement of the three-dimensional resonance triggering probe and the positioning of the three-dimensional resonance triggering. Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. The present invention uses PVDF piezoelectric film as a simply supported beam and a micro force sensor at the same time, and uses an integrated micro measuring rod measuring ball to form a vibrating beam type three-dimensional measuring head, which can realize high-precision three-dimensional shape measurement for various micro devices.

2. The vibrating beam-type three-dimensional measuring head of the present invention works in a resonant state, and the integrated micro-rod measuring head and the sample are scanned in tap mode or friction mode with hundreds of nN-level micro-measurement force, which can realize low-destructive micro-scale measurement of soft materials. force measurement.

3. It has been verified by experiments that the present invention can achieve sub-nanometer resolution in the three directions of X, Y and Z, wherein the system measurement resolution in the X direction is about 0.22nm; the system measurement resolution in the Y direction is about 0.29nm; the vertical resolution of the system in the Z direction is about 0.26nm.

Description of drawings

Figure 1a is a schematic diagram of the PVDF three-dimensional resonant probe of the present invention working in the Z direction;

Figure 1b is a schematic diagram of the PVDF three-dimensional resonant probe of the present invention working in the X and Y directions;

Fig. 2a is the amplitude-frequency diagram of the probe PVDF piezoelectric film of the present invention;

Fig. 2b is an amplitude-frequency diagram after the PVDF piezoelectric film of the probe of the present invention is combined with the micro-rod measuring ball;

Fig. 3 a is a schematic diagram of free vibration of the PVDF measuring head in the Z direction in the present invention;

Fig. 3b is a free vibration waveform diagram of the PVDF probe in the Z direction in the present invention;

Fig. 4a is a schematic diagram of the vibration of the PVDF probe when the Z-direction micro-rod measuring ball lightly touches the sample in the present invention;

Figure 4b is a vibration waveform diagram of the PVDF measuring head when the measuring ball of the Z-direction micro measuring rod lightly touches the sample in the present invention;

Figure 5a is a schematic diagram of the free vibration of the PVDF measuring head in the X and Y directions in the present invention;

Fig. 5b is a free vibration waveform diagram of the PVDF measuring head in the present invention;

Figure 6a is a schematic diagram of the vibration of the PVDF measuring head when the micro measuring rod in the X and Y directions measures the ball friction sample in the present invention;

Fig. 6b is the vibration waveform diagram of the PVDF measuring head when the micro measuring rod in the X and Y directions measures the ball friction sample in the present invention;

Fig. 7a is the experimental result of X direction force curve in the present invention;

Fig. 7b is the experimental result of Y direction force curve among the present invention;

Fig. 7c is the experimental result of Z direction force curve in the present invention;

Numbers in the figure: 1 is the PVDF piezoelectric film; 2 is the piezoelectric driver; 3 is the T-shaped probe holder; 4 is the integrated micro-rod probe; 5 is the sample; 6 is the sinusoidal AC signal; 7 is the differential charge signal.

Detailed ways

In this embodiment, the structural form of the three-dimensional resonance trigger probe based on PVDF is:

As shown in Figure 1a and Figure 1b, the PVDF piezoelectric film 1 is used as a vibrating beam with a simply supported beam structure, and it is also used as a micro force sensor. The left and right ends of the PVDF piezoelectric film 1 are respectively fixed on two PZT with the same structure. On the outside of the piezoelectric actuator 2, the inner sides of two piezoelectric actuators 2 with the same structure are symmetrically fixed on both sides of the T-shaped probe frame 3, and an integrated micrometer is fixed on the central position of the lower surface of the PVDF piezoelectric film 1. The rod measuring head 4 and the sample 5 are placed horizontally.

A sinusoidal AC signal is applied to the piezoelectric driver 2 as an excitation signal to drive the PVDF piezoelectric film 1 to drive the integrated micro-rod probe 4 to work in a resonance state;

Set the integrated micro-rod probe 4 driven by the PVDF piezoelectric film 1 to perform the test in the Z direction on the surface of the sample 5 as a tapping mode; set the integrated micro-probe probe 4 driven by the PVDF piezoelectric film 1 The test in the X direction and Y direction on the side of the sample 5 is the friction mode; the signal processing circuit is set to detect and process the change of the differential charge signal on the polarized surface of the PVDF piezoelectric film 1, so as to characterize the integrated micrometer The degree of contact between the rod probe 4 and the sample 5.

Measurement methods:

The sample 5 is placed horizontally, and the piezoelectric driver 2 is excited by a sinusoidal AC signal 6, so that the probe system composed of the PVDF piezoelectric film 1 and the integrated micro-rod probe 4 reaches a resonance state and freely vibrates with a constant amplitude. The PVDF piezoelectric film 1 The surface generates polarized charge signals; at the same time, the PVDF piezoelectric film 1 is used as a micro-force sensor, when the integrated micro-rod measuring head 4 contacts the surface of the sample 5 in the tapping mode in the Z direction or in the friction mode in the X and Y directions At this time, due to energy leakage, the amplitude of the PVDF piezoelectric film 1 measuring head system decreases, and the surface charge attenuates. The differential charge signal 7 is amplified through detection processing and compared with the set voltage signal to output the differential pressure signal. Combined with the control system to achieve Amplitude feedback control, that is, to realize the resonance trigger measurement and positioning of the probe system in the X, Y, and Z directions, and obtain the corresponding force curve graph.

In this embodiment, the three-dimensional resonance triggering positioning method of the PVDF-based three-dimensional resonance triggering probe is: the three-dimensional resonance triggering probe remains stationary, and the translation of the sample 5 in the horizontal plane completes the three-dimensional resonance triggering probe on the surface of the sample. or the sample 5 remains still, and the three-dimensional trigger positioning on the sample surface is completed by the translation of the three-dimensional resonance trigger probe in the horizontal plane.

Figure 2a shows the amplitude-frequency diagram of the PVDF piezoelectric film without an integrated micro-rod probe, the resonance frequency is about 3470Hz, the corresponding pre-amp voltage signal amplitude is 0.79V, and the quality factor Q is about 45 ; Figure 2b shows the amplitude-frequency diagram of the combination of the PVDF piezoelectric film and the integrated micro-rod probe, the resonant frequency is 2406Hz, the resonant peak value is 2.6V, and the quality factor Q is about 29.

Figure 3a is a schematic diagram of the free vibration of the PVDF three-dimensional resonance triggering probe in the Z direction, and Figure 3b is a free vibration waveform diagram of the PVDF three-dimensional resonance triggering probe in the Z direction. In Figure 3b, the abscissa t represents time, and the ordinate A represents the resonance amplitude of the probe system . When the one-piece micro-probe probe is not in contact with the sample, the probe system is in a free resonance state with a large amplitude A ₀ , as shown in Figure 3a and Figure 3b; due to the resonance state, the PVDF piezoelectric film probe system is highly sensitive to the micro-force Sensitivity, when the one-piece micro-rod probe continuously approaches the sample surface to tap mode contact, the energy leakage causes the probe system amplitude to attenuate to A ₁ , as shown in Figure 4a and Figure 4b.

Similarly, Fig. 5a and Fig. 5b show the free vibration diagram and free vibration waveform diagram of the PVDF three-dimensional resonance trigger probe in the X and Y directions respectively. Figure 6b is the vibration waveform diagram of the probe system in this friction mode.

The three-dimensional resonant trigger probe of the present invention has a sub-nanometer spatial resolution. Through experimental tests, the system noise level in the X direction is about 6mV, the sensitivity can reach 27.7V/μm, and the system vertical resolution is 0.22nm, as shown in Figure 7a Show. The system noise level in the Y direction is about 9mV, the sensitivity can reach 31.1V/μm, and the system vertical resolution is 0.29nm, as shown in Figure 7b. The noise level of the system in the Z direction is about 9mV, the sensitivity can reach 35V/μm, and the vertical resolution of the system is 0.26nm, as shown in Figure 7c.

Claims (2)

1. A three-dimensional resonance trigger measuring head based on PVDF is characterized in that: adopt PVDF piezoelectric film (1) as the vibrating beam with simply supported beam structure, the left and right ends of described PVDF piezoelectric film (1) are respectively It is fixed on the outside of two piezoelectric drivers (2) of the same structure, and the inner sides of the two piezoelectric drivers (2) of the same structure are symmetrically fixed on both sides of the T-shaped probe frame (3). The central position of the lower surface of the PVDF piezoelectric film (1) is fixedly equipped with an integrated micro measuring rod measuring head (4); A sinusoidal AC signal is applied to the piezoelectric driver (2) as an excitation signal to drive the PVDF piezoelectric film (1) to drive the integrated micro-rod probe (4) to work in a resonance state; It is set that the integrated micro measuring rod measuring head (4) driven by the PVDF piezoelectric film (1) carries out the test in the Z direction on the surface of the sample (5) as a tap mode; it is set by the PVDF piezoelectric film ( 1) The integrated micro-rod measuring head (4) driven by the friction mode is used to test the X direction and Y direction on the side of the sample (5); to detect the differential charge on the polarized surface of the PVDF piezoelectric film (1) The change of the signal is used to characterize the contact degree between the integrated micro measuring rod measuring head (4) and the sample. 2. A three-dimensional resonance trigger positioning method based on the PVDF-based three-dimensional resonance trigger measuring head of claim 1, characterized in that the three-dimensional resonance triggering measuring head remains motionless, and the translation of the sample (5) in the horizontal plane The three-dimensional triggering positioning of the three-dimensional resonance triggering probe on the sample surface is completed; or the sample (5) remains still, and the three-dimensional triggering positioning on the sample surface is completed by the translation of the three-dimensional resonance triggering probe in the horizontal plane.