JP3830662B2 - Optical axis adjustment mechanism of scanning probe microscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical axis adjustment mechanism of a scanning probe microscope, and in particular, in an optical axis adjustment mechanism from a laser light source to a photodetector in a scanning probe microscope having an optical lever type optical detection system such as an atomic force microscope. The present invention relates to an optical axis adjustment mechanism that enables automation.
[0002]
[Prior art]
A conventional method for adjusting the optical axis in a scanning probe microscope will be described with reference to FIGS. It is assumed that the illustrated scanning probe microscope is an atomic force microscope. The optical axis adjustment means that the laser beam from the laser light source is appropriately reflected on the back surface of the cantilever and is incident on the photodetector in the optical lever optical detection system of the atomic force microscope. Conventional optical axis adjustment has been performed manually by an operator. FIG. 5 schematically shows a configuration of a main part of an atomic force microscope including a cantilever and an optical lever type optical detection system.
[0003]
A cantilever 103 having a probe 102 at the tip is arranged with respect to the sample 101 to be measured. Reference numeral 104 denotes a part of the cantilever holder. The distance between the probe 102 and the surface of the sample 101 is such a distance that an atomic force acts between them. The measurement of the concavo-convex shape on the sample surface requires the probe 102 to move along the sample surface, and therefore the distance between the probe and the sample surface is held at a constant distance by the control mechanism. The change in the distance between the probe and the sample surface is detected by the displacement due to the bending deformation of the cantilever 103. An optical lever type optical detection system is provided as a mechanism for detecting a displacement due to the bending deformation of the cantilever 103. The optical lever type optical detection system includes a laser light source 105, mirrors 106 and 107, and a quadrant photodetector 108. When the optical axis adjustment of the optical lever type optical detection system is completed and measurement is performed, the laser beam 109 emitted from the laser light source 105 is reflected by the mirror 106, guided to the back surface of the cantilever 103, and reflected by the back surface of the cantilever 103. The laser beam 109 is further reflected by the mirror 107 and guided to the light receiving surface of the quadrant photodetector 108. The displacement of the cantilever 103 is detected as a change in the position of the irradiation spot of the laser beam 109 on the quadrant photodetector 108. An optical microscope 111 having a TV camera 110 is disposed above the cantilever 103, and the back surface of the cantilever 103 is observed by the optical microscope 111. The detection signal output from the quadrant photodetector 108 is sent to the control device, and the light receiving position of the laser beam can be displayed on the display device by the detection signal. The image observed with the optical microscope 111 is sent to the control device as a video signal by the TV camera 110 and displayed on the display device. In FIG. 5, illustration of the control device and the display device is omitted for the sake of simplicity of explanation.
[0004]
In the above configuration, the mirrors 106 and 107 are provided with a position adjusting mechanism that is manually operated. The optical axis adjustment is performed by the operator who performs measurement operating the position adjustment mechanism of the mirrors 106 and 107. Conventional optical axis adjustment consists of the following two steps.
[0005]
The first step of adjusting the optical axis is to apply an irradiation spot of the laser beam 109 to the reflective surface on the back surface of the cantilever 103. Confirmation of the spot position on the cantilever 103 is performed based on an image obtained by the optical microscope 111. An example is shown in FIG. FIG. 6 is an image of the cantilever 103 and its periphery viewed from above with the optical microscope 111. In the first step, the irradiation spot of the laser beam 109 is finally applied to the back surface of the cantilever 103. This operation is performed by manually operating the position adjustment mechanism of the mirror 106 while viewing the image by the optical microscope 111. Reference numeral 112 denotes a laser beam irradiation spot applied to the back surface of the cantilever 103. In a stage before the irradiation spot is applied to the back surface of the cantilever 103, it is preferable that the irradiation spot of the laser beam is applied to the upper surface of the cantilever holder 104. Reference numeral 113 denotes an irradiation spot applied to the upper surface of the cantilever holder 104. The reason for this is that the cantilever 103 is floating in the air, so that it is difficult to confirm the spot position if the irradiation spot is off the back surface of the cantilever 103. Therefore, the spot position is applied to the upper surface of the cantilever holder 104 where it is easy to confirm. In the operation of the first step, the laser beam irradiation spot is moved from the position 113 to the position 112 as indicated by the arrow 114. FIG. 7 is a side view showing the movement (arrow 115) of the laser beam 109 in the first step.
[0006]
The second step of adjusting the optical axis is to apply an irradiation spot based on the laser beam 109 reflected by the back surface of the cantilever 103 to the center of the light receiving surface of the quadrant photodetector 108. Confirmation of the spot position on the quadrant photodetector 108 is performed based on the detection signal. FIG. 8 illustrates the adjustment of the irradiation spot in the quadrant photodetector. FIG. 8 shows spot movement states {circle around (1)} to {circle around (4)} on the light receiving surface of the quadrant photodetector 108 and its peripheral region. In the second step, the irradiation spot 116 of the laser beam 109 is finally applied to the center position of the light receiving surface of the quadrant photodetector 108. This operation is performed by manually operating the position adjustment mechanism of the mirror 107.
[0007]
When the laser beam 109 is guided to the quadrant photodetector 108 by operating the position adjustment mechanism of the mirror 107, if the irradiation spot hits a part of the light receiving surface of the quadrant photodetector 108, the irradiation spot is centered on the light receiving surface. It is easy to guide. This is the state indicated by (2) in FIG. That is, in the quadrant photodetector 108, the light receiving surface is divided into four parts a, b, c, and d, and their detection signals are Sa to Sd, the total output signal Ss of the quadrant photodetector 108, and the vertical displacement. The component Sv and the horizontal displacement component Sh are obtained as Ss = Sa + Sb + Sc + Sd, Sv = {(Sa + Sb) − (Sc + Sd)} / Ss, Sh = {(Sa + Sc) − (Sb + Sd)} / Ss, respectively. Then, the mirror 107 may be adjusted so that Sv and Sh are minimized. When both Sv and Sh are 0, the irradiation spot 116 of the laser beam 109 is set at the center position of the light receiving surface.
[0008]
On the other hand, even if the cantilever 103 is a cantilever of the same standard, the reflection direction of the laser beam greatly varies depending on the characteristics of the surface coating condition and the like, and the irradiation spot of the laser beam hits a position far from the quadrant photodetector 108. Sometimes. This state is shown in (1) of FIG. Reference numeral 116 denotes an irradiation spot position. In this state, Ss is 0, and no information can be obtained from the detection signal output from the quadrant photodetector 108, so the spot position is completely unknown. As described above, in the second step, the mirror 107 is operated to obtain the Ss signal. However, since it is not known which position it is currently in, it is unknown which direction it should be moved first. It is. Conventionally, in practice, the irradiation spot 116 is moved appropriately and appropriately while monitoring Ss, and stopped when the output of Ss is output. Since such a state corresponds to (2) in FIG. 8, as described above, the spot can be adjusted to move to the center position.
[0009]
As described above, the optical axis adjustment for the optical lever type optical detection system is completed by executing the first step and the second step.
[0010]
[Problems to be solved by the invention]
Conventional optical axis adjustment in the optical lever type optical detection system is performed manually by the operator, and human eyes are indispensable when the irradiation spot is aligned with the cantilever in the first step, and the initial stage of the second step. In some cases, trial and error are necessary, so it is difficult to fully automate the optical axis adjustment. The laser beam irradiation spot can be aligned with the cantilever by image processing or the like, but the scale of the apparatus increases. Further, since cantilevers having the same shape are not always used at the time of measurement, conventionally, it has been common for a skilled observation operator to adjust the optical axis while looking through an optical microscope.
[0011]
It is also conceivable that the optical axis adjustment operation can be automated using the detection signal output from the quadrant photodetector 108. However, since the laser beam reflected from the cantilever is far from the light receiving surface of the quadrant photodetector 108 and does not hit the light receiving surface, it is actually difficult.
[0012]
Further, it is possible to automate the process of trial and error in the second step. In this case, in order to automate the process efficiently, the spot of the laser beam reflected by the cantilever is relatively divided into four parts. It is necessary to exist in the vicinity of the light receiving surface.
[0013]
An object of the present invention is to solve the above-mentioned problems, and automates the optical axis adjustment work of the optical lever optical detection system in the scanning probe microscope of the optical lever optical detection system, and is easy for an observer with little experience. It is another object of the present invention to provide an optical axis adjustment mechanism for a scanning probe microscope that can perform measurement operations.
[0014]
[Means and Actions for Solving the Problems]
The optical axis adjustment mechanism of the scanning probe microscope according to the present invention is configured as follows to achieve the above object.
The first optical axis adjusting mechanism (corresponding to claim 1) includes a cantilever having a probe arranged so as to face the sample, and a laser beam from the laser light source is guided to the cantilever by the first reflector and irradiated. The laser beam reflected from the cantilever is applied to a scanning probe microscope including an optical lever type optical detection system configured to guide the laser beam reflected by the second reflector to the photodetector. A first adjustment unit that changes the reflection direction of the reflector, a second adjustment unit that changes the reflection direction of the second reflector, an excitation unit that applies vibration for adjusting the optical axis to the cantilever, and a detection output from the photodetector It is comprised from the control means which controls operation | movement of a 1st adjustment part and a 2nd adjustment part based on a signal. With this configuration, the excitation unit generates vibration for adjusting the optical axis of the cantilever, thereby forming a laser beam expansion irradiation region that overlaps the light receiving surface of the photodetector, and the control means performs the first operation based on the detection signal of the photodetector. The operation of the adjusting unit and the second adjusting unit is controlled to automatically adjust the optical axis of the optical lever type optical detection system.
In the above configuration, when the laser beam is incident on the photodetector, the optical axis adjustment vibration is generated in the cantilever so that the laser beam is irradiated on the back surface of the cantilever. The enlarged irradiation region is formed instead of the laser beam irradiation spot, so that the laser beam can be detected easily, quickly and reliably by the photodetector. As a result, the control means can automatically adjust the optical axis of the optical lever type optical detection system by monitoring the detection signal output from the photodetector.
In the second optical axis adjustment mechanism (corresponding to claim 2), in the first configuration, the excitation unit includes a vertical vibration piezoelectric element and a torsional vibration piezoelectric element, and the optical axis adjustment vibration is for vertical vibration. It is characterized in that it is formed by synthesizing the vertical vibration by the piezoelectric element and the torsional vibration by the torsional vibration piezoelectric element. When the vertical vibration and the torsional vibration are combined, the enlarged irradiation region formed by this is formed in a rectangular shape, and an irradiation region having a wide area can be formed.
In the third optical axis adjustment mechanism (corresponding to claim 3), in each of the above configurations, the operation of the first adjustment unit is first controlled to set the reflection direction of the first reflector, and then the second adjustment is performed. The operation of the unit is controlled, and the reflection direction of the second reflector is set so that the irradiation spot of the laser beam is positioned at the center of the light receiving surface. The optical axis adjustment is configured to individually adjust the reflection direction of the first reflector and the reflection direction of the second reflector.
The fourth optical axis adjustment mechanism (corresponding to claim 4), in the third configuration, when the operation of the second adjustment unit is controlled, the vibration for optical axis adjustment by the excitation unit is gradually reduced, The laser beam expansion irradiation region can be changed to an irradiation spot. According to this configuration, even if the irradiation area by the laser beam becomes a normal irradiation spot, it is possible to always obtain a sum signal in the output signal of the photodetector.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
[0016]
The optical axis adjustment mechanism of the scanning probe microscope according to the present invention will be described with reference to FIGS. This scanning probe microscope is an atomic force microscope as an example. FIG. 1 shows a configuration of a main part of a general atomic force microscope including a cantilever and an optical lever type optical detection system.
[0017]
In FIG. 1, a support frame 11 is disposed below the center, and the support frame 11 is provided with an XYZ scanner 13 for placing a sample 12 thereon. In the illustrated example, the sample 12 is arranged horizontally, and the upper surface thereof is a surface to be observed. The sample 12 is moved in the horizontal direction (XY direction) and the vertical direction (Z direction) by the XYZ scanner 13. A support column 14 is provided near the XYZ scanner 13, and a cantilever 16 is attached to the upper portion of the support column 14 via a vibrating piezoelectric portion 15. The tip of the cantilever 16 faces the sample 12, and a minute probe 17 is attached to the tip. The tip of the probe 17 is close to the surface of the sample 12 at a very small distance. Reference numeral 18 denotes an arithmetic control device that performs various arithmetic processes, and is constituted by, for example, a computer.
[0018]
In an actual apparatus, the cantilever 16 and the pressurizing vibration element 15 are extremely fine. However, FIG. 1 is exaggerated and drawn for convenience of illustration.
[0019]
FIG. 2 shows an enlarged view of the portions of the vibrating piezoelectric portion 15 and the cantilever 16. The vibrating piezoelectric portion 15 is fixed to the tip of the support column 14. The exciting piezoelectric portion 15 includes three elements 15a, 15b, and 15c. 15a is a piezoelectric element for vertical vibration, and 15b and 15c are piezoelectric elements for torsional vibration. The cantilever 16 moves up and down as indicated by the arrow 19 by the vertical vibration piezoelectric element 15a, and the cantilever 16 is twisted as indicated by the arrow 20 by the torsional vibration piezoelectric elements 15b and 15c. The vertical vibration piezoelectric element 15 a is driven by an AC signal supplied from the first oscillator 21, and the torsional vibration piezoelectric elements 15 b and 15 c are driven by opposite-phase AC signals supplied from the second oscillator 22. The oscillating operations (voltage, frequency and phase of the output AC signal) of the first oscillator 21 and the second oscillator 22 are controlled based on the control signal from the arithmetic control device 18. The base end of the cantilever 16 is fixed to the lower surface of the vibrating piezoelectric portion 15. In the above configuration, the probe 17 is brought close to the surface of the sample 12 at the time of measurement, and the atomic force is maintained between the probe and the sample.
[0020]
When the surface of the sample 12 is scanned with the probe 17 at the tip of the cantilever 16 to measure the concavo-convex shape of the sample surface, the position of the cantilever 16 is set so that the distance between the probe 17 and the sample surface is kept constant. Be controlled. The position control of the cantilever is performed by changing the position of the sample 12 with the XYZ scanner 13 and changing the relative positional relationship between the cantilever 16 and the sample 12. The operation of the XYZ scanner 13 is also performed under the control of the arithmetic control device 18.
[0021]
An optical detection system is provided above the cantilever 16. A combination of the optical detection system and the cantilever constitutes an optical lever type optical detection system that detects the displacement of the cantilever. The optical lever type optical detection system is a mechanism that detects a displacement caused by the deformation of the cantilever 16 by irradiating the back surface of the cantilever 16 with a laser beam. The optical lever type optical detection system includes a laser light source 23, a first mirror 24, a second mirror 25, and a quadrant photodetector 26. Each of the first mirror 24 and the second mirror 25 includes tilt mechanisms 27 and 28 for changing the reflection direction of the mirror. The tilting mechanism 27 changes the mounting angle of the first mirror 24, and the tilting mechanism 28 changes the mounting angle of the second mirror 25. The laser light 29 emitted from the laser light source 23 is reflected by the first mirror 24 and guided to the back surface of the cantilever 16. The laser beam 29 reflected from the back surface of the cantilever 16 is reflected by the second mirror 25 and guided in the direction of the light receiving surface of the quadrant photodetector 26. In the state where the optical axis adjustment for measurement is completed in the optical lever type optical detection system, the laser light from the laser light source 23 is reflected by the first mirror 24 and incident on the back surface of the cantilever 16, and further on the back surface of the cantilever 16. The reflected laser light is reflected by the second mirror 25 and maintained in a state where it is incident on the quadrant photodetector 26. The optical axis adjustment in the optical lever optical detection system of the atomic force microscope according to this embodiment is automatically performed.
[0022]
Each of the tilt mechanisms 27 and 28 receives a control signal supplied from the arithmetic and control unit 18, and the operation of the tilt mechanism is controlled by the control signal. The operation of the tilt mechanism is controlled when the optical axis is adjusted, whereby the mounting angles of the first mirror 24 and the second mirror 25 are appropriately adjusted. Further, detection signals (Sa, Sb, Sc, Sd described above) output from the quadrant photodetector 26 are input to the arithmetic control device 18. The arithmetic control unit 18 incorporates a function unit (optical axis adjustment unit) for automatically performing optical axis adjustment. The optical axis adjustment unit controls the operation of the tilt mechanisms 27 and 28 while monitoring the detection signal of the quadrant photodetector 26 and sets the mounting angle of the first mirror 24 and the second mirror 25 to an appropriate angle. Adjust the optical axis.
[0023]
In the automatic optical axis adjustment according to the present embodiment, the optical axis adjustment unit operates the first oscillator 21 and the second oscillator 22 while monitoring the detection signal output from the quadrant photodetector 26, and the cantilever 16. Is oscillated in combination with vertical vibration and torsional vibration. When composite vibration is generated in the cantilever 16, when an irradiation spot of laser light is formed on the back surface of the cantilever 16, the incident laser light is beaten on the back surface of the cantilever compared to when the composite vibration is not generated, and the cantilever 16 The laser beam reflected from the back surface becomes an irradiation region further enlarged beyond that. This state is shown in FIG. The incident laser beam 29 is reflected by the back surface of the cantilever 16 by the vertical vibration 19 and the torsional vibration 20, and then forms an enlarged irradiation region 30. The enlarged irradiation region 30 is formed by moving the original irradiation spot (the conventional normal irradiation spot 116 shown in FIG. 8) at a high speed by vertical vibration and torsional vibration. It is formed as a region.
[0024]
Next, a method for automatically adjusting the optical axis will be described with reference to FIGS. The optical axis adjustment is performed, for example, when the cantilever is replaced. In the atomic force microscope, the cantilever is a consumable item and is frequently replaced. Therefore, when the cantilever is replaced, the optical axis is adjusted. There is no guarantee that the laser beam 29 is incident on the back surface of the cantilever 16 and an irradiation spot is formed at the stage where the cantilever 16 is attached to the vibrating piezoelectric portion 15. Therefore, automatic adjustment of the optical axis is performed.
[0025]
In the automatic adjustment of the optical axis, with the laser light output from the laser light source 23, the tilting mechanism 27 is first operated to change the mounting angle of the first mirror 24, and the laser light near the tip of the cantilever 16 is changed. 29 is scanned. In the scanning operation of the laser light 29, the scanning direction is preferably moved so that the scanning direction is substantially perpendicular to the longitudinal direction of the cantilever 16, and is moved little by little in the longitudinal direction. In FIG. 3, reference numeral 31 denotes a movement locus of the laser beam 29. Note that the movement trajectory 31 shown in FIG. 3 is exaggerated and is not actually changed as much as shown. On the other hand, in the cantilever 16, the vertical vibration and the torsional vibration are generated by the vertical vibration piezoelectric element 15 a and the torsional vibration piezoelectric elements 15 b and 15 c of the excitation piezoelectric portion 15 as described above. When the vibration is generated in the cantilever 16, when the laser beam 29 that performs the scanning operation as shown in FIG. 3 crosses a part of the cantilever 16, an enlarged irradiation region 30 having a large area is formed as described in FIG. It is done.
[0026]
At the stage where the enlarged irradiation region 30 is formed, the tilt mechanism 28 of the second mirror 25 is not specifically adjusted, and the second mirror 25 is set at a standard mounting angle, for example. However, since the enlarged irradiation region 30 thus produced has a large area, the possibility that the laser light 29 will strike the light receiving surface of the quadrant photodetector 26 is extremely high. Therefore, if the laser beam 29 is scanned as shown in FIG. 3 by controlling the operation of the tilt mechanism 28 while monitoring the detection signal of the four-divided photodetector 26, the laser beam 29 can be mounted at any angle. It is possible to determine whether the light 29 is irradiated on the back surface of the cantilever 16 to form an irradiation spot.
[0027]
The above state will be described with reference to the table of FIG. In the table shown in FIG. 4, the case where the irradiation spot of the laser beam 29 hits the cantilever 16 and the case where it does not hit are compared with the conventional method and the present invention. In the conventional method, the irradiation spot 116 of the laser beam having a diameter of about 1 mm is irradiated to the quadrant photodetector 26 having a circular light receiving surface having a diameter of about 3 mm. Is extremely difficult to detect. In contrast, in the method of adjusting the optical axis according to the present invention, the above-described enlarged irradiation region 30 is formed on the light receiving surface of the quadrant photodetector 26. The enlarged irradiation region 30 has a considerably larger area than the irradiation spot 116, and as a result, there is a very high possibility that a part of the enlarged irradiation region 30 overlaps the light receiving surface of the quadrant photodetector 26. As described above, in the optical axis adjustment according to the present invention, when the mounting angle of the first mirror 24 is adjusted, the cantilever 16 is held in a predetermined vibration state by the vibrating piezoelectric portion 15, so that the four-divided photodetector is used. An enlarged irradiation region 30 having a wide area is formed with respect to the light receiving surface 26, and the laser light 29 can be reliably captured by the quadrant photodetector 26. Therefore, by monitoring the output signal of the quadrant photodetector 26, it can be determined whether or not the laser beam 29 has formed an irradiation spot on the back surface of the cantilever 16. The mounting angle of the first mirror 24 is fixed in a state where the irradiation spot of the laser beam 29 is formed on the back surface of the cantilever.
[0028]
In the next stage, the operation of the tilt mechanism 28 is controlled to adjust the second mirror 25. Adjustment of the mounting angle of the second mirror 25 is performed by mounting the second mirror 25 with the tilt mechanism 28 so that the sum (Ss) of the output signals of the four portions a to d of the four-split photodetector 26 is maximized. The angle is changed and the position of the enlarged irradiation region 30 on the light receiving surface of the quadrant photodetector 26 is adjusted. In this way, the optical axis adjustment can be automatically performed relatively roughly.
[0029]
Finally, the second mirror 25 is adjusted so that the original laser beam irradiation spot is positioned at the center of the four-split photodetector 26 in a state where the vibration state of the cantilever 16 by the excitation piezoelectric portion 15 is finished. To do. However, if the vibration state of the cantilever 16 is suddenly stopped, the irradiation spot may be too small to obtain the sum signal. Therefore, the sum signal is reliably acquired while gradually decreasing the output signals of the first oscillator 21 and the second oscillator 22, and the second mirror 25 is adjusted so that the obtained sum signal becomes maximum. When the oscillation state of the cantilever 16 ends, that is, when the outputs of the first oscillator 21 and the second oscillator 22 become 0, the irradiation spot of the laser beam 29 on the quadrant photodetector 26 is (3) in FIG. It is in the state of. Thereafter, the second mirror 25 is adjusted so that the vertical displacement component Sv and the horizontal displacement component Sh are minimized based on the detection signal output from the quadrant photodetector 26. The adjustment of the mounting angle of the second mirror 25 is performed by controlling the operation of the mechanism 28 as a control signal of the arithmetic control device 18.
[0030]
As is apparent from the above steps, the optical axis adjustment of the optical lever type optical detection system is automatically performed under the control of the arithmetic and control unit 18.
[0031]
Although the atomic force microscope has been described in the above embodiment, the present invention is not limited to this, and the optical axis adjustment mechanism according to the present invention can be applied to a scanning probe microscope including an optical lever type optical detection system. The enlarged irradiation region 30 is formed by applying a vibration obtained by combining the vertical vibration and the torsional vibration to the cantilever 16, but an enlarged irradiation region having a wide area can be formed around the quadrant photodetector 26. Any vibration for adjusting the optical axis can be provided.
[0032]
【The invention's effect】
As is clear from the above description, according to the present invention, in the scanning probe microscope equipped with the optical lever type optical detection system, the cantilever is enlarged so that the irradiation area of the laser beam formed near the photodetector is enlarged. Because it is configured to give vibration for adjusting the optical axis to the optical axis, the optical axis adjustment that has been performed by an experienced measurement operator in the past is automatically performed by monitoring the detection signal output from the photodetector. Can do.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a scanning probe microscope provided with an optical axis adjusting mechanism according to the present invention.
FIG. 2 is an enlarged perspective view of a cantilever and an excitation piezoelectric unit.
FIG. 3 is a perspective view showing a state in which laser light is scanned by changing the mounting angle of the first mirror.
FIG. 4 is an explanatory diagram comparing a conventional method and a method of the present invention when a laser beam irradiation spot is applied to the back surface of a cantilever.
FIG. 5 is a schematic side view for explaining conventional optical axis adjustment.
FIG. 6 is an enlarged plan view of a cantilever part.
FIG. 7 is an enlarged side view of a cantilever part.
FIG. 8 is a diagram showing a control state in which the spot position is moved around the light receiving surface of the quadrant photodetector.
[Explanation of symbols]
11 Support frame
12 samples
13 XYZ scanner
15 Piezoelectric unit for vibration
15a Piezoelectric element for vertical vibration
15b, 15c Torsional vibration piezoelectric element
16 Cantilever
17 Probe
18 Arithmetic control device
21 First oscillator
22 Second oscillator
23 Laser light source
24 First mirror
25 Second mirror
26 Quadrant photodetector
27, 28 tilt mechanism
29 Laser light
30 Extended irradiation area

Claims (4)

A cantilever having a probe arranged so as to face the sample, a laser beam from a laser light source is guided to the cantilever by a first reflector, and the laser beam reflected from the cantilever is irradiated by a second reflector In a scanning probe microscope comprising an optical lever type optical detection system configured to be guided and incident on a photodetector,
A first adjustment unit for changing a reflection direction of the first reflector;
A second adjustment unit for changing a reflection direction of the second reflector;
An excitation unit for applying vibration for adjusting the optical axis to the cantilever;
Control means for controlling operations of the first adjustment unit and the second adjustment unit based on a detection signal output from the photodetector;
A laser beam expansion irradiation region that overlaps a light receiving surface of the photodetector is formed by generating vibration for adjusting the optical axis of the cantilever by the excitation unit, and the control means is based on the detection signal of the photodetector. An optical axis adjustment mechanism for a scanning probe microscope, wherein the optical axis adjustment of the optical lever type optical detection system is automatically performed by controlling the operations of the first adjustment unit and the second adjustment unit. The excitation unit includes a vertical vibration piezoelectric element and a torsional vibration piezoelectric element, and the optical axis adjustment vibration is formed by combining vertical vibration by the vertical vibration piezoelectric element and torsional vibration by the torsional vibration piezoelectric element. The optical axis adjusting mechanism of the scanning probe microscope according to claim 1. First, the operation of the first adjustment unit is controlled to set the reflection direction of the first reflector, and then the operation of the second adjustment unit is controlled so that the irradiation spot of the laser beam is on the light receiving surface. The optical axis adjustment mechanism of the scanning probe microscope according to claim 1 or 2, wherein the reflection direction of the second reflector is set so as to be positioned at the center. When the operation of the second adjustment unit is controlled, the vibration for optical axis adjustment by the excitation unit is gradually reduced, and the laser beam expansion irradiation region is changed to the irradiation spot. 4. An optical axis adjustment mechanism of a scanning probe microscope according to 3.

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