JP2003199368A - Actuator, actuator using the same and scanning probe microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator having a resonance frequency higher than that of the actuator of the shape of a normal quadrangular prism. <P>SOLUTION: The actuator 10 comprises an end 12 and an end 14 parallel to each other, and an axis 16 orthogonal to the ends 12 and 14. The end 14 is an end to be fixed, that is, a fixed end, and hence the end 12 is a free end. An area of the end face of the end 12 is smaller than that of the end face of the end 14. The actuator 10 is solid, and has a shape of a truncated pyramid, or more specifically, a shape of a truncated quadrangular pyramid. Accordingly, the section of the actuator 10 cut by a plane perpendicular to the axis 16 is a square shape, an its area is reduced monotonously, from the fixed end 14 toward the end 12. More specifically, the area of the section of the actuator 20 is reduced continuously. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator capable of generating displacement along one axis, and more particularly to an actuator used for a scanning mechanism such as a scanning probe microscope.

[0002]

2. Description of the Related Art In a scanning probe microscope, for example, while the probe and the sample are relatively raster-scanned (XY scan) in the XY directions, the interaction between the sample and the probe is constant also in the Z direction. Is a device for obtaining surface information of a desired region of the sample by performing feedback control (Z scanning) as described above.

The scanning mechanism has an actuator for moving the probe or the sample (XY scanning and Z scanning), and a piezoelectric actuator is generally used for this. The scanning mechanism is configured by combining, for example, a plurality of quadrangular prism-shaped stacked piezoelectric actuators that can be displaced along one axis.

[0004]

In the scanning probe microscope, improvement in measurement speed is desired. For this,
The scanning mechanism needs to be able to scan the probe or the sample at high speed. For high speed scanning, the actuator of the scanning mechanism needs to have a high resonance frequency. After all, an actuator having a high resonance frequency is desired.

An object of the present invention is to provide an actuator having a high resonance frequency. Another object of the present invention is to provide a scanning probe microscope having a high measurement speed.

[0006]

SUMMARY OF THE INVENTION The present invention is, in part, an actuator that causes a displacement in response to an input of electric energy, the actuator having a fixed end and a free end, and the area of the end face of the free end is the fixed end. Is smaller than the area of the end face.

One of the inventions is an actuator unit using an actuator that produces a displacement with respect to an input of electric energy, and has a pair of actuators and a supporting member for supporting them, and each actuator is fixed. It has an end and a free end, the area of the end surface of the free end is smaller than the area of the end surface of the fixed end, and the pair of actuators are arranged in a face-to-face manner with the support member interposed therebetween.

The present invention is, in part, a scanning probe microscope using an actuator that produces a displacement with respect to the input of electric energy. The actuator has a fixed end and a free end, and the area of the end face of the free end is fixed. It is smaller than the area of the end face.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an actuator of the present invention is shown in FIG.

As shown in FIG. 1, the actuator 10 has ends 12 and 14 which are parallel to each other, and an axis 16 which is orthogonal to them. The end 14 is a fixed or fixed end and thus the end 12 is a free end. The area of the end surface of the free end 12 is smaller than the area of the end surface of the fixed end 14.

The actuator 10 is solid and has a shape of a truncated pyramid, more specifically, a truncated pyramid.
Therefore, the cross section of the actuator 10 taken in a plane perpendicular to the axis 16 is square and its area decreases monotonically from the fixed end 14 to the free end 12. More specifically, the area of the cross section of the actuator 10 is continuously decreasing. However, the area of the cross section of the actuator 10 may be reduced discontinuously.

The actuator 10 is, for example, a piezoelectric actuator using a piezoelectric material, and more specifically, a laminated piezoelectric actuator. Such an actuator 10 can be easily manufactured by shaving an ordinary quadrangular prism-shaped laminated piezoelectric actuator, or by laminating a large number of rectangular plate-shaped piezoelectric bodies having slightly different sizes.

The actuator 10 is not limited to a piezoelectric actuator, but may be an actuator using an electrostrictive material or another suitable material.

Actuator 10 extends along axis 16 in response to input of electrical energy. That is, the free end 12 of the actuator 10 is displaced along the axis 16 in response to the input of electrical energy.

The actuator 10 of this embodiment has a high resonance frequency as compared with an actuator having an ordinary rectangular prism shape. Therefore, the scanning mechanism using the actuator 10 of the present embodiment can perform scanning at a higher speed than the scanning mechanism using the actuator having the shape of a regular square pole. This makes it possible to increase the measuring speed of the scanning probe microscope.

The inventor of the present invention has an actuator 10 in the shape of a truncated pyramid, one side of the free end of which is one third of the fixed end.
Simulations were performed in comparison with an actuator in the shape of a quadrangular prism having the same length. According to this, the actuator 10 in the shape of a truncated pyramid is about 1.7 in the transverse vibration mode as compared with the actuator in the shape of a quadrangular prism.
It was confirmed to have a resonance frequency of 5 times and about 3 times in the longitudinal vibration mode.

Another embodiment of the actuator of the present invention is shown in FIG.

As shown in FIG. 2, the actuator 20 has ends 22 and 24 that are parallel to each other and an axis 26 that is orthogonal to them. The end 24 is a fixed end and the end 22 is a free end. The area of the end surface of the free end 22 is smaller than the area of the end surface of the fixed end 24.

The actuator 20 is solid and has the shape of a truncated cone. Therefore, the cross section of the actuator 20 taken along a plane perpendicular to the axis 26 is circular, and its area decreases monotonically and continuously from the fixed end 24 to the free end 22.

The actuator 20 is, for example, a piezoelectric actuator using a piezoelectric material, and more specifically, a laminated piezoelectric actuator. The actuator 20 as described above can be easily manufactured by cutting an ordinary laminated piezoelectric actuator in the shape of a rectangular prism or laminating a large number of circular plate-shaped piezoelectric bodies having slightly different diameters.

The actuator 20 of this embodiment has a high resonance frequency as compared with an actuator having the shape of a regular square pole. Therefore, the scanning mechanism using the actuator 20 of the present embodiment can perform scanning at higher speed than the scanning mechanism using the actuator having the shape of a regular square pole. This makes it possible to increase the measuring speed of the scanning probe microscope.

Another embodiment of the actuator of the present invention is shown in FIG.

As shown in FIG. 3, the actuator 30 has an end 32 and an end 34 which are parallel to each other, and an axis 36 which is orthogonal to the ends 32 and 34. The end 34 is a fixed end and the end 32 is a free end. The area of the end surface of the free end 32 is smaller than the area of the end surface of the fixed end 34.

The actuator 30 is solid and has a prismatic shape, that is, a prism shape or a wedge shape. The actuator 30 has two side surfaces that are parallel to the shaft 36 and two side surfaces that are equally inclined with respect to the shaft 36. The cross section of the actuator 30 taken along a plane perpendicular to the axis 36 is rectangular and its area decreases monotonically and continuously from the fixed end 34 to the free end 32.

The actuator 30 is, for example, a piezoelectric actuator using a piezoelectric material, and more specifically, a laminated piezoelectric actuator. Such an actuator 30 can be easily manufactured by cutting a normal laminated piezoelectric actuator in the shape of a square pole, or by laminating a large number of rectangular plate-shaped piezoelectric bodies having slightly different sizes.

The actuator 30 of this embodiment has a high resonance frequency as compared with an actuator having the shape of a regular square pole. Therefore, the scanning mechanism using the actuator 30 of the present embodiment can perform scanning at a higher speed than the scanning mechanism using the actuator having the shape of a regular square pole. This makes it possible to increase the measuring speed of the scanning probe microscope.

Another embodiment of the actuator of the present invention is shown in FIG.

As shown in FIG. 4, the actuator 40 has ends 42 and 44 which are parallel to each other and an axis 46 which is orthogonal to them. The end 44 is a fixed end and the end 42 is a free end. The area of the end surface of the free end 42 is smaller than the area of the end surface of the fixed end 44.

The actuator 40 is solid and has a prismatic shape, that is, a prism shape or a wedge shape. The actuator 40 has three side surfaces that are parallel to the shaft 46 and one side surface that is inclined with respect to the shaft 46. Actuator 40 cut by a plane perpendicular to the axis 46
Has a rectangular cross section, and its area monotonically and continuously decreases from the fixed end 44 toward the free end 42.

The actuator 40 is, for example, a piezoelectric actuator using a piezoelectric material, and more specifically, a laminated piezoelectric actuator. The actuator 40 as described above can be easily manufactured by cutting an ordinary quadrangular prism-shaped laminated piezoelectric actuator or laminating a large number of rectangular plate-shaped piezoelectric bodies having slightly different sizes.

The actuator 40 of this embodiment has a high resonance frequency as compared with the actuator having the shape of a regular square pole. Therefore, the scanning mechanism using the actuator 40 of the present embodiment can perform scanning at a higher speed than the scanning mechanism using the actuator having the shape of a regular square pole. This makes it possible to increase the measuring speed of the scanning probe microscope.

Another embodiment of the actuator of the present invention is shown in FIG.

As shown in FIG. 5, the actuator 50 has an end 52 and an end 54 which are parallel to each other, and an axis 56 which is orthogonal to the ends 52 and 54. The end 54 is a fixed end and the end 52 is a free end. The area of the end surface of the free end 52 is smaller than the area of the end surface of the fixed end 54.

The actuator 50 is hollow and the shaft 5
6 has a through hole 58 extending along it. The actuator 50 has a truncated cone appearance. The cross section of the actuator 50 taken along a plane perpendicular to the axis 56 has the shape of an annular zone, and its area monotonically and continuously decreases from the fixed end 54 to the free end 52.

The actuator 50 is, for example, a piezoelectric actuator using a piezoelectric material. Such an actuator 50 can be manufactured by shaving a cylindrical piezoelectric material used for an ordinary cylindrical piezoelectric actuator and providing electrodes on the inner and outer peripheral surfaces thereof. Alternatively, it can be easily manufactured by stacking a large number of plate-shaped piezoelectric bodies in the shape of annular zones having slightly different diameters.

The actuator 50 of this embodiment has a high resonance frequency as compared with an ordinary actuator having a rectangular prism shape. Therefore, the scanning mechanism using the actuator 50 of the present embodiment can perform scanning at a higher speed than the scanning mechanism using the actuator having the shape of a regular square pole. This makes it possible to increase the measuring speed of the scanning probe microscope.

Another embodiment of the actuator of the present invention is shown in FIG.

As shown in FIG. 6, the actuator 60 has ends 62 and 64 which are parallel to each other, and an axis 66 which is perpendicular to these ends. The end 64 is a fixed end and the end 62 is a free end. The area of the end surface of the free end 62 is smaller than the area of the end surface of the fixed end 64.

The actuator 60 is hollow and has a shaft 6
6 has a through hole 68 extending along it. The actuator 60 has a quadrangular prism shape. The cross section of the actuator 60, taken along a plane perpendicular to the axis 66, is a square with a circular opening in the center, the area of which decreases monotonically and continuously from the fixed end 64 to the free end 62.

The actuator 60 is, for example, a piezoelectric actuator using a piezoelectric material, and more specifically, a laminated piezoelectric actuator. Such an actuator 60 is obtained by forming a through-hole in a normal quadrangular prism-shaped laminated piezoelectric actuator, or by laminating a large number of rectangular plate-shaped piezoelectric bodies having slightly different through-hole sizes. Easy to make.

The actuator 60 of this embodiment has a high resonance frequency as compared with an actuator having the shape of a regular square pole. Therefore, the scanning mechanism using the actuator 60 of the present embodiment can perform scanning at a higher speed than the scanning mechanism using the actuator having the shape of a regular square pole. This makes it possible to increase the measuring speed of the scanning probe microscope.

An embodiment of the actuator unit of the present invention is shown in FIG.

As shown in FIG. 7, the actuator unit 70 includes a pair of actuators 72 and 74.
And a support member 76 that supports them.

The two actuators 72 and 74 are the same, and each of them is, for example, the actuator 10 in the shape of the truncated pyramid described above. However, the two actuators 72 and 74 may be any of the actuators described above.

The two actuators 72 and 74 are both fixed to a supporting member 76, and are arranged in a plane-symmetric manner with the supporting member 76 interposed therebetween.

In this actuator unit 70,
A moving object or a scanning object is attached to either one of the two actuators 72 and 74. The same electric energy is input to the two actuators 72 and 74. Thus, the free ends of the two actuators 72 and 74 are symmetrically displaced in opposite directions.

The actuator unit 7 of this embodiment
When 0, the support member 76 hardly vibrates even when the actuators 72 and 74 are driven to expand and contract. That is, there is little vibration. It is considered that this is because the force received by the support member 76 due to the expansion and contraction of one actuator is canceled by the expansion and contraction of the other actuator.

Therefore, the scanning mechanism using the actuator unit 70 of the present embodiment has a higher resonance frequency than the normal scanning mechanism using the actuator, and therefore can perform scanning at high speed and generate less vibration.
This makes it possible to improve the measurement speed and measurement accuracy of the scanning probe microscope.

An embodiment of the scanning probe microscope of the present invention is shown in FIG.

In FIG. 8, the scanning probe microscope 10
0 roughly consists of a scanning probe microscope function part and an optical microscope function part.

The scanning probe microscope function part includes a housing 101, an optical sensor unit 102, a sensor unit Z stage 103, a slide glass 104, a slide glass holding portion 105, a cantilever chip 106, a scanning mechanism holding base 107, and a scanning mechanism. 200, actuator drive circuit 112, scan control circuit 113, feedback circuit 114, AC / DC conversion circuit 115, oscillation circuit 11
6, preamplifier circuit 117, semiconductor laser drive circuit 11
8 has a computer 119 and a monitor TV 120.

The optical microscope function part includes a microscope observation illumination optical system 11 including a light source lamp 139 lens 138.
0, microscope observation observation optical system 11 including eyepiece lens 140
1, half prism 137, microscope illumination lamp power supply 12
1. Further, it has an objective lens 122 of the optical sensor unit 102 which is also used as a scanning probe microscope function part.

Description will be added to the part of the function of the scanning probe microscope. The scanning mechanism holding base 107 is supported at three points on the housing 101 by three micrometer heads 135 (only two of which are shown in FIG. 8) that can be micro-fed manually. Further, the scanning mechanism 200 is supported by the scanning mechanism holding table 107, and the sample 109 is attached to the scanning mechanism 200 so as to face downward in the figure, that is, to face the cantilever tip 106 side. The scanning mechanism 200 finely scans the sample 109 in the X, Y, and Z directions. The details of the scanning mechanism 200 will be described later. The scanning mechanism 200 includes the probe 132 of the cantilever tip 106 and the sample 10 in each of the X, Y, and Z directions.
An adjusting mechanism for performing rough adjustment of the position with respect to 9 may be provided.

The optical sensor unit 102 is an optical lever type optical sensor for measuring the movement of the cantilever 131 of the cantilever chip 106. The optical sensor unit 102 includes an objective lens 122 and an objective lens support 12
3, a prism 124, a polarization beam splitter 125,
Collimating lens 126, semiconductor laser 127, laser position adjusting stage 128, two-divided photodiode 12
9. It has a photodiode position adjusting stage 130.

The light emitted from the semiconductor laser 127 is
After being collimated by the collimator lens 126, it is reflected by the polarization beam splitter 125, and then the prism 124
Is further reflected by and enters the objective lens 122. Parallel light
The cantilever chip 10 is focused by the objective lens 122.
The light is focused on the back surface of the cantilever 131 of No. 6. The light reflected on the back surface of the cantilever 131 follows the opposite path,
After passing through the polarization beam splitter 125, the light beam further proceeds straight to reach the two-divided photodiode 129. Cantilever 1
The angular displacement of 31 is reflected in the movement of the light spot on the two-divided photodiode 129 and is output as an electric signal.

Objective lens 1 of optical sensor unit 102
Reference numeral 22 configures an optical microscope observation optical system together with the microscope observation illumination optical system 110 and the microscope observation observation optical system 111, and enables the optical microscope observation of the sample 109. The objective lens 122 is an objective lens for an optical microscope and has, for example, a magnification of 20 times.

The Z stage 103 for the sensor unit is
A stage for coarsely adjusting the position of the optical sensor unit 102 including the objective lens 122. The objective lens 122 included in the optical sensor unit 102 is moved up and down to focus the optical sensor and focus for microscope observation. .

The slide glass holder 105 holds the slide glass 104. Slide glass holder 105
An excitation piezoelectric body 133 for exciting the cantilever 131 is fixed at a position apart from the mounting portion of the cantilever chip 106. An AC voltage in the vicinity of the resonance frequency of the cantilever 131 is applied to the excitation piezoelectric body 133, and the excitation piezoelectric body 1 is applied in response to this voltage application.
33 vibrates, and the vibration is transmitted to the cantilever tip 106 and vibrates the cantilever 131.

In the measurement in which the cantilever 131 is vibrated as described above, the displacement signal of the cantilever output from the optical sensor unit 102 becomes AC. The AC / DC conversion circuit 115 converts this into a DC signal. For measurements in which the cantilever 131 is not vibrated, this circuit may be bypassed and not operated.

Further, FIG. 8 shows a state of observation in a liquid. Water 134 hangs from the vicinity of the sample 109 of the scanning mechanism 200 to the vicinity of the slide glass 104 to which the cantilever tip 106 is fixed. Sample 10
Both 9 and cantilever tip 106 are located in the water. The water 134 is not necessary when the measurement is performed in the atmosphere.

As shown in FIG. 8, the scanning probe microscope 100 includes an electric circuit for controlling / driving the device. These circuit operations are similar to the circuit operations of the scanning probe microscope proposed in the past.

The scan control circuit 113 includes a computer 1
A control signal for XYZ scanning is given from 19. Figure 8
The signal indicated by Z is a signal for adjusting the distance between the actuator for scanning in the Z direction of the scanning mechanism 200 and the probe 132 of the cantilever tip 106. The Z signal is output from the computer mainly when setting the measurement conditions such as the force curve measurement before measurement. Further, the computer 119 controls the oscillation circuit 116 to operate the excitation piezoelectric body 133 to vibrate the cantilever 131 near its resonance frequency.

When the measurement is started, the raster scanning control signal output from the computer 119 (indicated by X and Y in the figure).
Based on the above, the actuator of the scanning mechanism 200 is scanned in the XY directions. The displacement of the cantilever 131 based on the interaction between the probe 132 at the tip of the cantilever 131 and the surface of the sample 109 is detected by the optical sensor unit 102, and the optical sensor unit 102 outputs the displacement signal. The displacement signal output from the optical sensor unit 102 is amplified by the preamplifier circuit 117 and input to the AC / DC conversion circuit 115. AC / DC conversion circuit 115
Extracts the signal of the frequency component of the reference signal from the oscillation circuit 116 and converts the AC signal into a DC signal.

The feedback circuit 114 uses the setting signal and AC / DC commanded by the computer 119.
The input signal from the conversion circuit 115 is compared and the Z direction feedback signal Zfb is sent to the scan control circuit 113. This Z-direction feedback signal Zfb becomes a scanning control signal for the Z-direction actuator. The scan control circuit 113 has a Z
The actuator drive circuit 112 is controlled based on the direction feedback signal Zfb to drive the actuator for the Z direction scanning of the scanning mechanism 200. Computer 119
Processes the surface information of the sample as three-dimensional information based on the XY scanning control signal generated by itself and the signal from the feedback circuit 114, and displays it on the monitor TV 120.

The scanning mechanism 200 will be described in detail with reference to FIG.

As shown in FIG. 9, the scanning mechanism 200
Is a scanning mechanism holding table 212 and a pedestal 2 fixed to the table.
14, 216 and actuator units 220, 240, 260 attached to the pedestals 214, 216.

The actuator unit 220 has, for example, a pair of actuators 222 and 224 that can expand and contract in the X direction, and a support member 226 that supports them. This is basically the same structure as the actuator unit 70 described above. The support member 226 is the base 21.
It is fixed at 4.

Similarly, the actuator unit 240
Has, for example, a pair of actuators 242 and 244 that can expand and contract in the Y direction, and a support member 246 that supports them. The structure is basically the same as that of the actuator unit 70 described above. The support member 246 is the pedestal 21.
It is fixed at 6.

The actuator unit 260 includes a pair of actuators 262 and 264 which can expand and contract in the Z direction.
And a support member 266 for supporting them.
The structure is basically the same as that of the actuator unit 70 described above. The support member 226 is fixed to the pedestals 214 and 216.

The actuator unit 260 further has a moving portion 272 attached to the end of the actuator 262. The moving unit 272 includes a holding unit 274 for holding an object to be scanned such as a sample.
For example, a sample table glass is attached to the end surface of the holding portion 274.

The actuator unit 220 has microspheres on the end surface of the actuator 222 (see FIG. 8), and the microspheres are attached to the side surface of the moving portion 272. Similarly, the actuator unit 240 is
The end surface of the actuator 242 has microspheres (see FIG. 8), and the microspheres are applied to the side surface of the moving section 272.

The microspheres of the actuator unit 220 act as a guide for the moving portion 272 with respect to the expansion / contraction motion of the actuator unit 240. Therefore, the actuator unit 220 does not prevent the movement of the moving portion 272 by the actuator unit 240. The same applies to the actuator unit 240. Therefore, the scanning mechanism 200 exhibits highly linear operation characteristics.

The scanning mechanism 200 has three actuator units 220, 240 and 260, each of which is basically the same as the actuator unit 70 described above. Therefore, even when the actuators are driven to expand and contract, the supporting portions hardly vibrate. For this reason,
The scanning mechanism 200 has a higher resonance frequency than the ordinary scanning mechanism using an actuator, and therefore can scan at high speed and generate less vibration. Therefore, the scanning probe microscope of this embodiment has high measurement speed and high measurement accuracy.

Although the embodiments of the present invention have been described with reference to the drawings, the present invention is not limited to the above-mentioned embodiments, and various modifications and alterations can be made without departing from the scope of the invention. It may be changed.

[0075]

According to the present invention, there is provided an actuator having a high resonance frequency as compared with an actuator having the shape of a regular square pole. In addition, an actuator unit that can scan at high speed with less vibration is provided. Furthermore, the measurement speed of the scanning probe microscope with high measurement speed is provided.

[Brief description of drawings]

FIG. 1 shows an embodiment of an actuator of the present invention.

FIG. 2 shows another embodiment of the actuator of the present invention.

FIG. 3 shows another embodiment of the actuator of the present invention.

FIG. 4 shows another embodiment of the actuator of the present invention.

FIG. 5 shows another embodiment of the actuator of the present invention.

FIG. 6 shows another embodiment of the actuator of the present invention.

FIG. 7 shows an embodiment of an actuator unit of the present invention.

FIG. 8 shows an embodiment of a scanning probe microscope of the present invention.

9 shows the scanning mechanism shown in FIG.

[Explanation of symbols]

10 actuators 12 Free end 14 fixed end

Claims (17)

[Claims] 1. An actuator that causes a displacement with respect to an input of electric energy, the actuator having a fixed end and a free end, and an area of an end face of the free end is smaller than an area of an end face of the fixed end. . 2. The actuator according to claim 1, wherein the actuator has an axis orthogonal to the fixed end and the free end, and an area of a cross section perpendicular to the axis monotonically decreases from the fixed end to the free end. 3. The actuator according to claim 2, wherein the area of the cross section perpendicular to the axis is continuously reduced. 4. The actuator according to claim 2, wherein the area of the cross section perpendicular to the axis is discontinuously reduced. 5. The actuator according to claim 3, wherein the actuator is solid. 6. The actuator according to claim 5, wherein the actuator has a truncated cone shape. 7. The actuator according to claim 5, wherein the actuator has a shape of a truncated pyramid. 8. The actuator according to claim 7, wherein the actuator has a wedge shape. 9. The actuator according to claim 3, wherein the actuator is hollow and has a through hole extending along the central axis. 10. The actuator according to claim 9, wherein the area of the through hole on the plane perpendicular to the axis monotonically increases from the fixed end to the free end. 11. The actuator according to claim 10, wherein the area of the through hole on the plane perpendicular to the axis continuously increases. 12. The actuator according to claim 11, wherein the actuator has an outer shape of a quadrangular prism. 13. The actuator according to claim 11, wherein the actuator has a truncated cone appearance. 14. The actuator according to claim 3, wherein the actuator is a piezoelectric actuator. 15. The actuator according to claim 14, wherein the actuator is a laminated piezoelectric actuator. 16. An actuator unit using an actuator that produces a displacement in response to an input of electric energy, the actuator unit having a pair of actuators and a support member for supporting the actuators, each actuator having a fixed end and a free end. An actuator unit having an end, the area of the end surface of the free end is smaller than the area of the end surface of the fixed end, and the pair of actuators are arranged in surface contrast with the support member interposed therebetween. 17. A scanning probe microscope using an actuator that produces a displacement with respect to an input of electric energy, wherein the actuator has a fixed end and a free end, and the area of the end face of the free end is the end face of the fixed end. Scanning probe microscope smaller than the area of.