Scanning probe microscope and method for adjusting optical axis in scanning probe microscope

Abstract

To suppress the adverse influence of the irregular reflection of laser light on the processing of the optical axis adjustment of the laser light in a scan type probe microscope.SOLUTION: The control device of the scan type probe microscope sets the position of a specified spot to an initial position, when the position of the spot of the laser light specified on the basis of an image captured by an imaging part is moved in a direction predicted when the laser light is moved. The control device specifies the position for allowing the irregular reflection on the basis of the image captured by the imaging part and moves the spot from the initial position to the top end of a cantilever, while avoiding the position for allowing the irregular reflection.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a scanning probe microscope and a method for adjusting an optical axis in a scanning probe microscope. [Background technology]

[0002] Scanning probe microscopes use a cantilever with a probe tip. In scanning probe microscopes, changes in the bending or vibration of the cantilever are converted into changes in the reflected light of a laser irradiated on the back of the cantilever, and detected by a photodetector. The photodetector detects changes in the position, intensity, and phase of the reflected light. Scanning probe microscopes convert the information detected by the photodetector into various physical information.

[0003] In a scanning probe microscope, before measuring a sample, it is necessary to adjust the optical axis of the laser beam so that the laser beam is correctly irradiated onto the back surface of the cantilever. Since the optical axis adjustment of the laser beam is a task that is required every time a cantilever is replaced, it is desirable that it be completed in a short time. Furthermore, since the optical axis adjustment of the laser beam is a task that is required every time a cantilever is replaced, it is desirable that it be performed automatically.

[0004] For example, Patent Document 1 (Japanese Patent No. 6627953) discloses a scanning probe microscope equipped with an image processing unit that identifies the position of the laser light spot and the position of the tip of the cantilever based on an image. The scanning probe microscope disclosed in Patent Document 1 further includes an optical axis adjustment unit that adjusts the position of the laser light source based on the identified position of the laser light spot and the position of the tip of the cantilever. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6627953 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the spot diameter of the laser light in a scanning probe microscope is in the nm to μm range. Therefore, the laser light may be diffusely reflected due to scratches on the surface irradiated with the laser light, dust attached to the surface irradiated with the laser light, or dust floating within the imaging range. The scanning probe microscope disclosed in Patent Document 1 does not take into consideration the diffuse reflection of the laser light.

[0007] The present invention has been made to solve such problems, and its object is to prevent diffuse reflection of laser light from adversely affecting the process of adjusting the optical axis of laser light in a scanning probe microscope. [Means for solving the problem]

[0008] A scanning probe microscope according to one aspect of the present invention includes a cantilever, a light source that emits laser light toward the cantilever, a moving mechanism that moves an irradiation position of the laser light on an irradiation surface of the laser light relative to the irradiation surface, an imaging unit that includes the cantilever in its imaging range, and a control device. The control device identifies a position where the laser light will be diffusely reflected based on an image captured by the imaging unit, and causes the moving mechanism to move the irradiation position relative to the irradiation surface so that the laser light is irradiated onto the cantilever while avoiding the position where the laser light will be diffusely reflected.

[0009] A scanning probe microscope according to another aspect of the present invention includes a cantilever, a light source that emits laser light toward the cantilever, a moving mechanism that moves the irradiation position of the laser light on a surface irradiated with the laser light relative to the irradiation surface, an imaging unit that includes at least a part of the irradiation surface in its imaging range, and a control device. The control device specifies the position of the spot of the laser light formed on the irradiation surface based on an image captured by the imaging unit, and specifies the irradiation position depending on whether the position of the spot specified based on an image obtained by moving the irradiation position by the moving mechanism is a position predicted by moving the irradiation position. Effect of the Invention

[0010] This makes it possible to prevent diffuse reflection of the laser light from adversely affecting the process of adjusting the optical axis of the laser light in the scanning probe microscope. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing a schematic configuration of a scanning probe microscope 1 of an embodiment. [Diagram 2] 10A and 10B are diagrams for explaining an outline of a method for adjusting an optical axis at the start of measurement. [Diagram 3] 2 is a vertical cross-sectional view of the upper part of the scanner 50 and the sample holder 52 when the sample S is observed. [Figure 4] This is an example of an image P obtained when the laser light LA ​​is irradiated on dust or the like and is diffusely reflected. [Diagram 5] 10 is a diagram for explaining an outline of a position adjustment process S1 of a laser light source 22 executed by a control device 100. FIG. [Figure 6] 13 is a flowchart of a specific process S100. [Figure 7] 1 is an example of an image P captured at an initial position. [Figure 8] 8 is an example of an image P obtained when the spot s1 is moved in the moving direction x in FIG. [Figure 9] 1 is an example of an image P captured at an initial position. [Figure 10] This is an example of an image P obtained when the spot s1 is moved in the moving direction x in FIG. [Figure 11] 13 is a flowchart of an adjustment process S300. [Figure 12] 13 is a flowchart of a fine adjustment process S330. [Figure 13] FIG. 13 is a diagram showing an example of a path taken by a spot s1 as a result of execution of an adjustment process S300. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are given the same reference characters, and their descriptions will not be repeated in principle.

[0013] [Configuration of scanning probe microscope 1] 1 is a diagram showing a schematic configuration of a scanning probe microscope 1 according to an embodiment. In the following, the contact surface of the scanning probe microscope 1 is defined as the XY plane, and the axis perpendicular to the XY plane is defined as the Z axis.

[0014] With reference to FIG. 1, a scanning probe microscope 1 comprises, as main components, a cantilever 10, a holder 14, an optical system 20, drive mechanisms 30 and 40, a scanner 50, a sample holder 52, an imaging section 60, and a control device 100.

[0015] During measurement, the cantilever 10 is disposed so as to be located above the sample S placed on the sample holder 52. The cantilever 10 is supported by a holder 14 so as to be capable of vibrating in the vertical direction, and has a probe 12 on the side not supported by the holder 14 (the tip side).

[0016] During measurement, the optical system 20 irradiates the back surface of the cantilever 10 (the surface opposite to the front surface facing the sample S) with laser light LA ​​and detects the laser light LA ​​reflected by the back surface of the cantilever 10. The control device 100 calculates the deflection of the cantilever 10 based on the laser light LA ​​detected by the optical system 20. The optical system 20 includes a laser light source 22, a beam splitter 24, a reflecting mirror 26, and a detector 28.

[0017] The laser light source 22 is composed of a laser oscillator that emits laser light LA, etc. The laser light LA ​​emitted from the laser light source 22 is reflected by a beam splitter 24 and irradiated onto the cantilever 10. The laser light LA ​​irradiated onto the cantilever 10 is reflected by the rear surface of the cantilever 10, and is further reflected by a reflecting mirror 26 to be incident on a detector 28. The detector 28 has a light receiving surface 280 for receiving the laser light LA ​​reflected by the rear surface of the cantilever 10. The detector 28 detects the laser light LA ​​received by the light receiving surface 280, and outputs the obtained detection result to the control device 100.

[0018] The driving mechanism 30 moves the laser light source 22 along a plane (the YZ plane in the example shown in FIG. 1) perpendicular to the optical axis of the laser light LA ​​emitted from the laser light source 22. The driving mechanism 30 drives a motor in accordance with a control signal from the control device 100 to move the laser light source 22, and the optical axis of the laser light LA ​​is adjusted so that the laser light LA ​​is reflected by the cantilever 10.

[0019] Driving mechanism 40 moves detector 28 along a plane (YZ plane in the example shown in FIG. 1) perpendicular to the optical axis of laser light LA ​​reflected by reflecting mirror 26 and incident on light receiving surface 280. Driving mechanism 40 moves detector 28, for example, by driving a motor in accordance with a control signal from control device 100, and the position of detector 28 is adjusted so that laser light LA ​​reflected by cantilever 10 is incident on the center of light receiving surface 280.

[0020] The scanner 50 has a cylindrical shape. The sample S is held on a sample holder 52 placed on the scanner 50. The scanner 50 has an XY scanner that scans the sample S in two mutually orthogonal axial directions of X and Y, and a Z scanner that finely moves the sample S in a Z-axis direction orthogonal to the X and Y axes. The XY scanner and the Z scanner are driven by piezoelectric elements that deform when a voltage is applied from a drive unit (not shown). The scanner 50 is driven in three dimensional directions by the XY scanner and the Z scanner.

[0021] The drive unit controls the XY scanner and the Z scanner in accordance with control signals from the control device 100 , thereby changing the relative positional relationship between the sample S on the scanner 50 and the probe 12 .

[0022] The imaging unit 60 is disposed above the probe 12 and images the cantilever 10 from above. The imaging unit 60 images a subject present in the imaging field of view to obtain image data. The imaging unit 60 mainly includes an optical system such as a lens and an aperture, and a light receiving element such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The imaging unit 60 outputs the obtained image data to the control device 100. The image data obtained by the imaging unit 60 is used, for example, to adjust the optical axis of the laser light LA.

[0023] The control device 100 controls the operation of each component constituting the scanning probe microscope 1. The control device 100 is configured according to a general-purpose computer architecture, as an example. Note that the control device 100 may be implemented using hardware dedicated to the scanning probe microscope 1. The control device 100 includes a processor 120, a memory 140, a display unit 160, and an input unit 180.

[0024] The processor 120 is typically an arithmetic processing unit such as a CPU (Central Processing Unit) or an MPU (Multi Processing Unit). The processor 120 reads out and executes a program stored in the memory 140 to realize each of the processes of the control device 100, which will be described later. 1 In this example, a configuration in which there is a single processor is illustrated, but the control device 100 may have multiple processors.

[0025] The memory 140 is realized by a non-volatile memory such as a random access memory (RAM), a read only memory (ROM), or a flash memory. The memory 140 stores programs executed by the processor 120, data used by the processor 120, and the like. For example, the memory 140 stores programs for executing a position adjustment process S1 of the laser light source 22 and a position adjustment process S2 of the detector 28, which will be described later.

[0026] In addition, memory 140 may be a CD-ROM (Compact Disc - Read Only Memory), a DVD-ROM (Digital Versatile Disk - Read Only Memory), a USB (Universal Serial Bus) memory, a memory card, a FD (Flexible Disk), a hard disk, an SSD (Solid State Drive), a magnetic tape, a cassette tape, an MO (Magnetic Optical Disc), an MD (Mini Disc), an IC (Integrated Circuit) card (excluding memory cards), an optical card, a mask ROM, or an EPROM, as long as it is capable of non-temporarily recording a program in a format readable by the control device 100, which is a type of computer.

[0027] The display unit 160 is configured with a liquid crystal display panel, etc. The display unit 160 displays, for example, the measurement results measured by the scanning probe microscope 1, or various setting screens for performing measurements by the scanning probe microscope 1, etc.

[0028] The input unit 180 is configured with a mouse, a keyboard, etc. The input unit 180 is an input interface that receives information input via the input unit 180. Note that the control device 100 may include a touch panel in which the display unit 160 and the input unit 180 are integrated.

[0029] [Optical axis adjustment at the start of measurement] In the scanning probe microscope 1, the optical system 20 must be adjusted so that the position of the laser light LA ​​reflected by the cantilever 10 (the position where the amount of received light is the greatest) when the cantilever 10 is not bent is incident on the center of the light receiving surface 280 of the detector 28. Such optical axis adjustment is performed every time the cantilever 10 is replaced.

[0030] 2 is a diagram for explaining an outline of a method for adjusting the optical axis at the start of measurement. The process relating to the optical axis adjustment includes a process S1 for adjusting the position of the laser light source 22 and a process S2 for adjusting the position of the detector .

[0031] When the control device 100 receives an instruction to start adjusting the optical axis, it executes a process S1 for adjusting the position of the laser light source 22. In the process S1 for adjusting the position of the laser light source 22, the control device 100 adjusts the position of the laser light source 22 so that a spot s1 formed by irradiating the sample holder 52 or the cantilever 10 with the laser light LA ​​is located at the tip of the cantilever 10. The control device 100 specifies the positional relationship between the spot s1 and the tip of the cantilever 10 based on the image P generated by the imaging unit 60. The control device 100 controls the driving mechanism 30 based on the specified positional relationship, and moves the laser light source 22 in the Y direction and the Z direction in the figure so that the spot s1 is located at the tip of the cantilever 10.

[0032] When the control device 100 determines that the spot s1 is located at the tip of the cantilever 10, it executes a process S2 for adjusting the position of the detector 28. The process S2 for adjusting the position of the detector 28 may be executed in response to receiving an instruction to start the process S2 for adjusting the position of the detector 28. In the process S2 for adjusting the position of the detector 28, the control device 100 adjusts the position of the detector 28 so that the spot s2 of the laser light LA ​​reflected by the cantilever 10 (the spot s2 formed by irradiating the light receiving surface 280 with the laser light LA) is located at the center of the light receiving surface 280.

[0033] The position adjustment process S2 of the detector 28 may be performed by a user. Specifically, an operation unit used to drive the drive mechanism 40 that moves the detector 28 may be further provided in the scanning probe microscope 1, and the position adjustment process S2 of the detector 28 may be realized by the user operating the operation unit based on the detection result from the detector 28.

[0034] [Configuration of sample holder 52] In this embodiment, the sample holding section 52 includes a mirror 522 for making it easier for the imaging section 60 to detect a spot s1 formed on the irradiation surface when the irradiation surface is irradiated with the laser light LA.

[0035] Fig. 3 is a vertical cross-sectional view of the upper part of scanner 50 and sample holder 52 when observing sample S. Referring to Fig. 3, a substantially doughnut-shaped pedestal part 54 having a cylindrical hole in the center is provided on the upper end surface of scanner 50.

[0036] The sample holder 52 includes a stub-type attachment 520 and a sample stage 540 . The stub-type attachment 520 has a convex shape on the lower side. The stub-type attachment 520 is fixed to the scanner 50 by inserting the convex part into a cylindrical hole provided in the center of the base part 54. The stub-type attachment 520 may be fixed to the scanner 50 with a screw or the like.

[0037] A recess 526 is formed on the upper surface of stub type attachment 520, and mirror 522 is placed inside recess 526. A magnet 524 is embedded inside stub type attachment 520. Stub type attachment 520 is made of aluminum.

[0038] The sample stage 540 is a stage for placing the sample S, and is made of metal. When observing a sample, the sample stage 540 is placed above the mirror 522. On the other hand, when adjusting the optical axis as described with reference to FIG. 2, the sample stage 540 is not placed above the mirror 522.

[0039] When the sample stage 540 is placed above the mirror 522, the sample stage 540 is fixed to the stub-type attachment 520 by the attractive force of the magnet 524 in the stub-type attachment 520. In addition, since the mirror 522 is placed inside the recess 526, a gap is formed between the mirror 522 and the sample stage 540 when the sample stage 540 is placed above the mirror 522.

[0040] 2 is performed in a state where the sample stage 540 is not placed above the mirror 522. Therefore, the laser light LA ​​is incident on the mirror 522 without being blocked by the sample stage 540. The laser light LA ​​reflected by the mirror 522 is incident on the imaging unit 60 without being blocked by the sample stage 540.

[0041] 2 will be described in the following, assuming that the optical axis adjustment described with reference to Fig. 2 is performed in a state where the sample stage 540 is not placed above the mirror 522. The optical axis adjustment may be performed in a state where the sample stage 540 is placed above the mirror 522. When the optical axis adjustment is performed in a state where the sample stage 540 is placed above the mirror 522, the optical axis adjustment may be performed in a state where a sample S having a high reflectance is placed on the sample stage 540.

[0042] That is, when the optical axis adjustment is performed with the sample stage 540 placed without the sample S, the surface on which the sample S is placed corresponds to the "irradiation surface", when the optical axis adjustment is performed with the sample S with a high reflectance placed on the sample stage 540, the surface of the sample S corresponds to the "irradiation surface", and when the optical axis adjustment is performed without the sample stage 540 being placed above the mirror 522, the mirror surface of the mirror 522 corresponds to the "irradiation surface". irradiation This corresponds to "face".

[0043] [Issues that arise when identifying the irradiation position of the laser light LA] The control device 100 specifies the position of a spot s1 formed by irradiating the irradiation surface with the laser beam LA, based on an image captured by the imaging unit 60. The control device 100 performs feedback control using the specified position of the spot s1 as the irradiation position of the laser beam LA, and aligns the irradiation position of the laser beam LA with the cantilever 10.

[0044] The spot diameter of the laser light LA ​​in the scanning probe microscope 1 is in the nm to μm range. Therefore, the laser light LA ​​may be diffused due to the influence of scratches formed on the surface irradiated with the laser light, dust attached to the irradiated surface, or dust floating within the imaging range. Note that substances attached to the irradiated surface that cause diffuse reflection include, but are not limited to, solution scattered during observation in liquid, and dust.

[0045] Furthermore, the imaging range of the imaging unit 60 used to identify the irradiation position of the laser light LA ​​is a field of view in the order of μm to mm, and an accuracy of nm to μm is required to identify the irradiation position of the laser light LA. Since the imaging range of the imaging unit 60 is in the order of μm to mm, there is a risk that the irradiation position of the laser light LA ​​(the position of the spot s1) cannot be identified accurately due to diffuse reflection of the laser light LA.

[0046] More specifically, with reference to Fig. 4, it will be described that the irradiated position of the laser light LA ​​may not be identified due to diffuse reflection of the laser light LA. Fig. 4 is an example of an image P obtained when the laser light LA ​​is irradiated on dust or the like and diffusely reflected. The shaded area in Fig. 4 is an area D indicating the location where the laser light LA ​​is diffusely reflected. The white area is a shadow r (high brightness area) of the laser light LA ​​reflected on the irradiation surface (mirror 522). Note that some symbols are omitted in Fig. 4.

[0047] 4, when the laser light LA ​​is diffusely reflected, the reflected light of the laser light LA ​​is incident on the imaging unit 60 from various directions, and a plurality of shadows r of the laser light LA ​​are reflected on the image P. Also, due to the diffuse reflection of the laser light LA, a spot s1 of the laser light LA ​​may not be formed at the irradiation position. The control device 100 may erroneously identify the shadow r reflected due to the diffuse reflection of the laser light LA ​​as the spot s1, and erroneously identify the irradiation position of the laser light LA.

[0048] For example, when the irradiation position of the laser light LA ​​on the camera coordinate system is position a in Fig. 4, the control device 100 may mistakenly determine that the spot s1 is formed at position b in Fig. 4 and that position b is the irradiation position of the laser light LA. That is, one problem caused by diffuse reflection of the laser light LA ​​is that the irradiation position of the laser light LA ​​cannot be accurately determined.

[0049] The control device 100 starts the optical axis adjustment in a state where the irradiation position of the laser beam LA is unknown. Therefore, there is a problem that the irradiation position of the laser beam LA cannot be accurately specified, and therefore the initial position of the irradiation position of the laser beam LA cannot be accurately specified.

[0050] If the initial position of the irradiation position identified based on the image P at the start of the optical axis adjustment is incorrect, the control device 100 ends up adjusting the irradiation position of the laser beam LA based on the incorrect position. As a result, a problem occurs in that it takes time to align the irradiation position of the laser beam LA on the cantilever 10, or the irradiation position of the laser beam LA cannot be aligned on the cantilever 10.

[0051] Furthermore, when aligning the irradiation position of the laser beam LA on the cantilever 10, adjustments must be made in nm to μm units. However, when moving the position of the laser light source 22 by driving a motor such as the driving mechanism 30, it is difficult to move the irradiation position of the laser beam LA in nm to μm units. For this reason, the control device 100 generally aligns the irradiation position of the laser beam LA by performing feedback control based on the image captured by the imaging unit 60.

[0052] In order to realize the feedback control, the control device 100 needs to specify the irradiation position of the laser light LA ​​by specifying the position of the spot s1 based on the image captured by the imaging unit 60. However, as described above, if the laser light LA ​​is diffusely reflected, the control device 100 may not be able to accurately specify the irradiation position of the laser light LA. Therefore, even if the initial position of the laser light LA ​​can be accurately specified, diffuse reflection of the laser light LA ​​may occur while the irradiation position of the laser light LA ​​is being moved, making it impossible to specify the accurate irradiation position, and accurate feedback control may not be possible. In other words, one problem caused by diffuse reflection of the laser light LA ​​is that accurate feedback control may not be possible.

[0053] In other words, diffuse reflection of the laser light LA ​​causes problems such as the inability to accurately identify the irradiation position of the laser light LA, the inability to identify the initial position of the irradiation position, or the inability to perform accurate feedback control, which has a negative impact on the process of adjusting the optical axis of the laser light LA.

[0054] [Position adjustment process S1 for laser light source 22] 5 is a diagram for explaining an outline of the position adjustment process S1 of the laser light source 22 executed by the control device 100. In this embodiment, the control device 100 specifies a spot s1 of the laser light LA ​​based on an image generated by the imaging unit 60, and adjusts the position of the laser light source 22 by controlling the drive mechanism 30 so that the irradiation position of the laser light LA ​​is located at the tip of the cantilever 10.

[0055] In order to solve the problem that the initial position of the irradiation position of the laser light LA ​​cannot be accurately specified, the scanning probe microscope 1 according to this embodiment performs a process of specifying the initial position of the irradiation position (specifying process S100). The specifying process S100 will be described later with reference to FIGS. 6 to 10.

[0056] In order to solve the problem that accurate feedback control cannot be performed after the initial position of the irradiation position is specified in the specifying process S100, the scanning probe microscope 1 according to this embodiment performs a process of adjusting the irradiation position of the laser light LA ​​(adjustment process S300). The adjustment process will be described later with reference to Figs. 11 to 13. After completing the adjustment process, the control device 100 ends the position adjustment process S1 of the laser light source 22.

[0057] [Specific Processing] The identification process S100 will be described in detail with reference to Fig. 6. Fig. 6 is a flowchart of the identification process S100.

[0058] In S102, the control device 100 determines whether or not the spot s1 is detected. More specifically, the control device 100 determines whether or not the spot s1 is formed on an irradiation surface included in an imaging range of the imaging unit 60. For example, the control device 100 determines whether or not the spot s1 is detected based on whether or not a predetermined number or more of pixels having a luminance equal to or higher than a predetermined threshold are included in the image.

[0059] When it is determined that the spot s1 is not detected (NO in S102), the control device 100 changes the irradiation position in S104. More specifically, the control device 100 controls the driving mechanism 30 to move the laser light source 22, thereby changing the irradiation position.

[0060] The control device 100 repeats the processes of S102 and S104 until the spot s1 is detected. When the control device 100 determines that the spot s1 is detected (YES in S102), the control device 100 executes the process of S106.

[0061] In S106, the control device 100 specifies the position of the spot s1. More specifically, the control device 100 specifies the position of the spot s1 in the image (in the camera coordinate system). For example, the control device 100 specifies an area close to a predetermined area (number of pixels) among areas showing pixels with a brightness equal to or higher than a predetermined threshold, and sets the position of the specified area in the image as the position of the spot s1. The predetermined area (number of pixels) is determined in advance based on, for example, the intensity of the laser light LA, the distance from the laser light source 22 to the irradiation surface, and the distance from the irradiation surface to the imaging unit 60.

[0062] In S108, the control device 100 stores the position of the laser light source 22 as an initial position.

[0063] In S110, the control device 100 sets a moving direction x, which is a direction in which the spot s1 moves relative to the irradiation surface.

[0064] In S112, the control device 100 moves the irradiation position in the movement direction x. More specifically, the control device 100 controls the drive mechanism 30 to move the laser light source 22 in a direction corresponding to the movement direction x, thereby moving the spot s1 in the movement direction x with respect to the irradiation surface.

[0065] In S114, the control device 100 identifies the position of the spot s1 based on an image captured after the spot s1 has been moved in the moving direction x.

[0066] In S116, the control device 100 judges whether the spot s1 has moved in the moving direction x on the image. More specifically, the control device 100 judges whether the moving direction of the spot s1 on the image predicted when the laser light source 22 is moved so as to move the spot s1 in the moving direction x with respect to the irradiation surface coincides with the moving direction from the spot position identified in S106 to the spot position identified in S114.

[0067] When it is determined that the spot s1 has not moved in the moving direction x on the image (NO in S116), the control device 100 determines whether or not all directions have been set in S118. More specifically, the control device 100 determines whether or not the spot s1 has been moved in all directions determined in advance around the initial position.

[0068] When it is determined that all directions have not been set (NO in S118), that is, when there is a moving direction x that has not been set, the control device 100 returns the position of the laser light source 22 to the initial position in S120, and executes the processes of S110 to S116 again. Note that in S110, the control device 100 sets the next moving direction x to be set based on the currently set moving direction x.

[0069] When it is determined that all directions have been set (YES in S118), the control device 100 ends the process in S122, assuming that there is an abnormality. In this case, the control device 100 ends the process related to the optical axis adjustment.

[0070] When it is determined that the spot s1 has moved in the moving direction x on the image (YES in S116), the control device 100 moves the irradiation position a predetermined distance in the moving direction x in S124. More specifically, the control device 100 controls the driving mechanism 30 to move the laser light source 22 and move the spot s1 a predetermined distance relative to the irradiation surface. The moving distance is preset according to, for example, the imaging range of the imaging unit 60.

[0071] In S126, the control device 100 determines whether the spot s1 has moved in the moving direction x on the image. More specifically, the control device 100 controls the imaging unit 60 to capture an image at a predetermined time while moving a predetermined distance, and identifies the position of the spot s1 for each image captured at each time. The control device 100 compares the position of each spot s1 identified for each image with the position of the spot identified in S106, thereby determining whether the spot s1 continues to move in the moving direction x on the image.

[0072] When it is determined that the spot s1 has not moved in the moving direction x on the image (NO in S126), the control device 100 executes the process from S118 onwards. That is, when all directions are set, the control device 100 terminates the process as there is an abnormality, and when there is a direction that has not been set, the control device 100 changes the direction and executes the process from S110 onwards again.

[0073] When it is determined that the spot s1 is moving in the moving direction x on the image (YES in S126), the control device 100 returns the position of the laser light source 22 to the initial position in S128 and ends the identification process S100. When the control device 100 ends the identification process S100, it returns to the position adjustment process S1 of the laser light source 22.

[0074] That is, the control device 100 changes the moving direction x in sequence by repeating S110 to S120. Then, when the moving direction of the spot s1 detected on the image does not match the moving direction x of the actually moved irradiation position (YES in S118) regardless of which moving direction x the spot s1 is moved to, the control device 100 determines in S122 that there is an abnormality and ends the process. Here, "there is an abnormality" in S122 means that the initial position of the irradiation position of the laser light LA ​​cannot be identified.

[0075] For example, when the laser beam LA is diffusely reflected at the initial position, or when the laser beam LA is diffusely reflected in any moving direction x, the control device 100 determines in S122 that an abnormality has occurred.

[0076] In addition, even if the laser light LA ​​is diffused at the initial position and the position of the spot s1 specified in S106 is different from the irradiation position, it is possible that the moving direction of the position of the spot s1 detected on the image coincides with the actually moved moving direction x. In this embodiment, by executing the processes of S124 and S126, it is possible to determine whether the position of the spot s1 specified in S106 is correct or not, taking into consideration a situation in which the moving direction of the position of the spot s1 detected on the image coincides with the actually moved moving direction x.

[0077] Furthermore, by executing the processes of S124 and S126, it is guaranteed that the area D is not located on the trajectory of the spot s1 moved in S124.

[0078] If it is determined that there is an abnormality, control device 100 may display information indicating that the initial position cannot be identified on display unit 160. Control device 100 may display information indicating a method for resolving the abnormality on display unit 160. Examples of the "method for resolving the abnormality" include a method for manually identifying the initial position, a method for removing dust adhering to mirror 522, and a method for moving mirror 522 so that an area with few scratches and dust on the mirror surface of mirror 522 is positioned within the imaging range.

[0079] An example of an image obtained by executing the identification process S100 will be described with reference to Figs. 7 to 10. Figs. 7 and 9 are an example of an image P captured at an initial position. Fig. 8 is an example of an image P obtained when the spot s1 is moved in the moving direction x in Fig. 7. Fig. 10 is an example of an image P obtained when the spot s1 is moved in the moving direction x in Fig. 9. The shaded areas in Figs. 7 to 10 are areas D indicating the locations where the laser light LA ​​is diffusely reflected. The white areas are shadows r (high brightness areas) of the laser light LA ​​reflected on the irradiation surface (mirror 522). Note that some reference symbols are omitted in Figs. 7 to 10.

[0080] 7 to 10 are camera coordinates, and X and Y coordinates are coordinates based on the scanning probe microscope 1. Positions a and a' in Fig. 7 to 10 indicate the irradiation position of the laser light LA ​​on the irradiation surface (on the XY coordinates). Positions b and b' indicate the position on the camera coordinates of the spot s1 identified by the control device 100 based on the image P.

[0081] In the example shown in FIG. 7, the laser light LA ​​is irradiated onto a diffusely reflected area D (position a(X1, Y1)). Even in this case, as shown in FIG. 7, the laser light LA ​​is diffusely reflected, causing multiple shadows r of the laser light LA ​​to appear on the image P. As a result, in the example shown in FIG. 7, the control device 100 is assumed to have determined that the spot s1 is formed at position b(x1, y1) (S106 in FIG. 6). In other words, the control device 100 is assumed to have determined that the initial position of the irradiation position on the camera coordinate system is position b(x1, y1).

[0082] When the irradiation position is moved in the moving direction x in Fig. 7 (S112 in Fig. 6), as shown in Fig. 8, the irradiation position of the laser light LA ​​moves away from the diffuse reflection position (area D), and a spot s1 is formed at a position a' (X2, Y2) on the irradiation surface, and the formed spot s1 is projected on the image P. Then, the control device 100 is assumed to have specified the position of the spot s1 as position b' (x2, y2) (S114 in Fig. 6). In other words, the control device 100 is assumed to have specified the irradiation position on the camera coordinate system as position b' (x2, y2).

[0083] As shown in Fig. 8, the moving direction x from position a (X1, Y1) to position a' (X2, Y2) does not match the moving direction x' from position b (x1, y1) to position b' (x2, y2). In this case, the control device 100 determines in S116 in Fig. 6 that the spot s1 is not moving in the moving direction x on the image P, and executes the processes from S118 onwards.

[0084] 9, the laser beam LA is not irradiated onto the diffusely reflecting region D, and a spot s1 is formed at the irradiation position, i.e., position a (X3, Y3), and the formed spot s1 is projected onto the image P. Then, the control device 100 is assumed to have determined that the initial position of the spot s1 is position b (x3, y3) (S106 in FIG. 6). In other words, the control device 100 is assumed to have determined that the initial position of the irradiation position on the camera coordinate system is position b (x3, y3).

[0085] When the irradiation position is moved in the moving direction x in Fig. 9 (S112 in Fig. 6), as shown in Fig. 10, the laser light LA ​​is not irradiated onto the diffusely reflected area D, and a spot s1 is formed at the irradiation position, position a' (X4, Y4), and the formed spot s1 is projected on the image P. Then, the control device 100 is assumed to have determined that the position of the spot s1 is position b' (x4, y4) (S106 in Fig. 6). In other words, the control device 100 is assumed to have determined that the irradiation position on the camera coordinate system is position b' (x4, y4).

[0086] As shown in Fig. 10, the moving direction x from position a (X3, Y3) to position a' (X4, Y4) coincides with the moving direction x' from position b (x3, y3) to position b' (x4, y4). In this case, the control device 100 determines in S116 in Fig. 6 that the spot s1 is moving in the moving direction x on the image P, and executes the processes from S124 onwards.

[0087] 7 and 8, when the position of the identified spot s1 does not move in the direction of the movement of the irradiation position before and after the movement, there is a high possibility that the laser light LA ​​is diffusely reflected at least before and after the movement. And there is a high possibility that the irradiation position of the laser light LA ​​on the identified image P is incorrect.

[0088] On the other hand, as shown in Figures 9 and 10, when the position of the identified spot s1 moves in the direction of the movement of the irradiation position before and after the movement, it is highly likely that the laser light LA ​​is not diffusely reflected either before or after the movement. And, it is highly likely that the irradiation position of the laser light LA ​​on the identified image P is correct.

[0089] That is, in this embodiment, the control device 100 specifies the position of the spot s1 of the laser light LA ​​formed on the irradiation surface based on the image P captured by the imaging unit 60. Then, the control device 100 controls the drive mechanism 30 to move the position of the laser light source 22 to change the irradiation position of the laser light LA, and specifies the irradiation position depending on whether the position of the spot s1 specified based on the image P obtained by changing the irradiation position is a position predicted by changing the irradiation position.

[0090] More specifically, the control device 100 moves the irradiation position in the movement direction x, and if the position of the spot s1 identified based on the image before the movement does not move in the movement direction x, it determines that the identified position of the spot s1 does not correspond to the irradiation position.

[0091] In the above embodiment, the control device 100 moves the irradiation position in the movement direction x, and even if the position of the spot s1 specified based on the image before the movement moves in the movement direction x, the control device 100 further moves the irradiation position by a predetermined distance in the movement direction x. Then, when the position of the spot s1 specified based on the image moves in the movement direction x in accordance with the movement of the irradiation position, the control device 100 determines that the position of the spot s1 specified based on the image corresponds to the irradiation position.

[0092] In addition, the control device 100 may move the irradiation position in the movement direction x without executing S124 and S126, and if it determines that the position of the spot s1 identified based on the image before the movement has moved in the movement direction x (YES in S116), it may execute the processing of S128, assuming that the position of the spot s1 identified based on the image corresponds to the irradiation position.

[0093] [Adjustment processing] As described above, the control device 100 adjusts the irradiation position of the laser light LA ​​by performing feedback control based on the image captured by the imaging unit 60. However, if the laser light LA ​​is diffusely reflected, the control device 100 may not be able to accurately identify the irradiation position of the laser light LA ​​based on the image P. Therefore, the control device 100 according to this embodiment executes an adjustment process S300 to identify the position where the laser light LA ​​is diffusely reflected, and adjusts the irradiation position of the laser light LA ​​to the cantilever 10 so that the laser light LA ​​does not pass through the position where the laser light LA ​​is diffusely reflected.

[0094] The adjustment process S300 will be described in detail with reference to Fig. 11. Fig. 11 is a flowchart of the adjustment process S300. The adjustment process S300 shown in Fig. 11 is executed when the position of the laser light source 22 is returned to the initial position (S128) and the process returns to the position adjustment process S1 of the laser light source 22 without terminating the process related to the optical axis adjustment as it is determined that there is an abnormality (S122) in the identification process S100 shown in Fig. 6. That is, the adjustment process S300 is executed when the control device 100 determines that the initial position has been correctly identified.

[0095] In S302, the control device 100 determines the position of the region D where the laser light LA ​​is diffusely reflected. For example, the control device 100 determines the region D where the laser light LA ​​is diffusely reflected based on an image obtained with the laser light source 22 turned off.

[0096] As an example, the control device 100 binarizes the image P based on the pixel values. Then, based on the binarized image, the control device 100 divides the area excluding the cantilever 10 and the holder 14 (the area corresponding to the mirror surface of the mirror 522) into one or more areas, and integrates the pixel values ​​in the vertical and horizontal directions (x and y directions) for each divided area. The integrated value of an area containing substances such as dust or scratches (an area including area D) will be larger than that of the mirror surface of the mirror 522. Therefore, the control device 100 can obtain the coordinates of the four corners of area D on the camera coordinate system.

[0097] That is, in this embodiment, the control device 100 specifies the position of the region D in the image where the laser light LA ​​is diffusely reflected within the range of the region in the image corresponding to the mirror 522. The region in the image corresponding to the cantilever 10 and the holder 14 is specified, for example, by known pattern matching.

[0098] The method of determining the position of area D on the camera coordinate system is not limited to the above method. For example, the control device 100 may perform pre-processing of noise removal on the image and determine the position of area D by comparing the image before and after noise removal. Filters used in the pre-processing may include an averaging filter, a dilation filter, a contraction filter, a median filter, etc. The control device 100 may also use a combination of these filters.

[0099] Furthermore, the control device 100 may assume that scratches and substances (for example, dust, solution, etc.) are particles and use a general particle analysis method to determine the position of the region D. Note that the method for determining the position of the region D is not limited to the above-mentioned example method.

[0100] In S304, the control device 100 determines a target position. The target position is, for example, the tip portion of the cantilever 10 on the side not supported by the holder 14. In S304, the spot s1 is located at the initial position of the spot s1 identified in S106.

[0101] In S306, the control device 100 determines whether or not it is possible to move toward the target position without passing through the region D. More specifically, the control device 100 determines whether or not the region D exists in the moving direction from the spot s1 to the target position. Note that if the distance between the spot s1 and the region D is sufficient, it may be determined that it is possible to move toward the target position without passing through the region D.

[0102] When it is determined that the spot s1 cannot be moved toward the target position (NO in S306), the control device 100 determines in S308 whether or not the spot s1 can be moved in a direction to avoid the area D. For example, the control device 100 determines whether or not the spot s1 can be moved within the imaging field of view of the imaging unit 60 so as to avoid the area D.

[0103] When it is determined that the laser light source 22 cannot be moved in a direction to avoid the region D (NO in S308), the control device 100 ends the process in S314 as there is an abnormality. In this case, the control device 100 ends the process related to the optical axis adjustment. At this time, the control device 100 may display on the display unit 160 information indicating that the position adjustment process S1 of the laser light source 22 could not be ended normally.

[0104] When it is determined that the irradiation position can be moved in a direction to avoid area D (YES in S308), in S310, the control device 100 moves the irradiation position in a direction to avoid area D. Note that, when there are multiple directions to avoid area D, the control device 100 may select a direction that is closer to the target position.

[0105] The control device 100 drives the driving mechanism 30 by a predetermined number of pulses in S310, and then determines the position of the spot s1 in S312. After determining the position of the spot s1, the control device 100 executes S306 again to determine whether or not the spot s1 can be moved toward the target position without passing through the region D.

[0106] The control device 100 repeats the processes of S308 to S312 until it is determined that the laser beam LA can be moved toward the target position without passing through the region D. That is, by repeating the processes of S308 to S312, the control device 100 can move the irradiation position of the laser beam LA so that the laser beam LA does not pass through the position where the laser beam LA is diffusely reflected.

[0107] When it is determined that the irradiation position can be moved toward the target position without passing through area D (YES in S306), the control device 100 moves the irradiation position toward the target position in S316.

[0108] The control device 100 drives the driving mechanism 30 for a predetermined number of pulses in S316, and then determines the position of the spot s1 in S318.

[0109] In S320, the control device 100 determines whether the distance between the target position and the position of the spot s1 is equal to or less than a predetermined threshold value.

[0110] When it is determined that the distance between the target position and the position of the spot s1 is longer than a predetermined threshold value (NO in S320), the control device 100 executes the processes from S306 onwards again to reduce the distance between the target position and the spot s1.

[0111] The control device 100 repeats the processes of S306 to S318 until it determines that the distance between the target position and the position of the spot s1 is equal to or less than the predetermined threshold. If it determines that the distance between the target position and the position of the spot s1 is equal to or less than the predetermined threshold (YES in S320), the control device 100 executes a fine adjustment process S330, then ends the adjustment process S300, returns to the position adjustment process S1 of the laser light source 22, finishes the position adjustment process S1 of the laser light source 22, and executes a position adjustment process S2 of the detector 28.

[0112] [Fine-tuning process] The fine adjustment process S330 will be described in detail with reference to Fig. 12. Fig. 12 is a flowchart of the fine adjustment process S330. The fine adjustment process S330 shown in Fig. 12 is a process executed at a timing when the distance between the target position and the position of the spot s1 becomes shorter than a predetermined threshold, and is a process for aligning the irradiation position with the tip of the cantilever 10.

[0113] In S332, the control device 100 moves the irradiation position toward the target position. The control device 100 continues to move the irradiation position toward the target position until it determines that the laser beam LA is irradiating the cantilever 10 (YES in S334).

[0114] Whether or not the laser light LA ​​is irradiated onto the cantilever 10 is determined based on, for example, whether or not the spot s1 is detected. While the laser light LA ​​is irradiated onto the mirror surface of the mirror 522, the control device 100 can identify the spot s1. On the other hand, if the surface of the cantilever 10 has the property of diffusively reflecting the laser light LA, the control device 100 will not be able to identify the spot s1 at the time when the laser light LA ​​is irradiated onto the cantilever 10. Therefore, the control device 100 may determine that the laser light LA ​​is irradiated onto the cantilever 10 when it is no longer possible to identify the spot s1.

[0115] When it is determined that the laser light LA ​​is being irradiated onto the cantilever 10 (YES in S334), the control device 100 stores as position A the position of the laser light source 22 at the time when it is determined that the laser light LA ​​is being irradiated onto the cantilever 10.

[0116] S33 8 In step S332, the control device 100 moves the irradiation position in the same direction. The same direction means the same direction as the direction in which the irradiation position was moved in step S332.

[0117] The control device 100 is S33 8 After driving the driving mechanism 30 for a predetermined number of pulses in S330, in S340, it is determined whether or not the laser beam LA has deviated from the cantilever 10. Whether or not the laser beam LA has deviated from the cantilever 10 is determined based on whether or not the spot s1 has been detected, similar to S334. The control device 100 may determine that the laser beam LA has deviated from the cantilever 10 when the spot s1 has been identified.

[0118] When it is determined that the laser beam LA has not deviated from the cantilever 10 (NO in S342), the control device 100 determines in S342 whether or not the spot s1 has deviated from the imaging field of view.

[0119] When it is determined that the spot s1 is out of the imaging field of view (YES in S342), the control device 100 ends the process in S344 as there is an abnormality. In this case, the control device 100 ends the process related to the optical axis adjustment. At this time, the control device 100 may display on the display unit 160 information indicating that the position adjustment process S1 of the laser light source 22 could not be ended normally.

[0120] If it is determined that the spot s1 has not deviated from the imaging field of view (NO in S342), the control device 100 executes the processes from S338 onwards again, and repeats the processes from S338 to S342 until it is determined that the laser light LA ​​has deviated from the cantilever 10 (YES in S340).

[0121] When it is determined that the laser beam LA has deviated from the cantilever 10 (YES in S340), the control device 100 stops the movement of the irradiation position in S346.

[0122] In S348, the control device 100 stores, as position B, the position of the laser light source 22 when it is stopped.

[0123] In S350, the control device 100 sets the position of the laser light source 22 to a position midway between positions A and B, ends the fine adjustment process S330, and returns to the adjustment process S300.

[0124] That is, in this embodiment, the control device 100 specifies the position of the region D where the laser light LA ​​is diffusely reflected based on the image captured by the imaging unit 60. Then, the control device 100 controls the drive mechanism 30 to move the position of the laser light source 22, thereby moving the irradiation position of the laser light source 22 so that the laser light LA ​​is irradiated onto the cantilever 10 while avoiding the position of the region D where the laser light LA ​​is diffusely reflected.

[0125] Furthermore, even if the control device 100 determines that the laser light LA ​​has been irradiated onto the cantilever 10, it continues to move the irradiation position until the laser light LA ​​is no longer irradiated onto the cantilever 10. Then, the control device 100 determines the position of the laser light source 22 based on the position A of the laser light source 22 when it has been determined that the laser light LA ​​has been irradiated onto the cantilever 10 and the position B of the laser light source 22 when it has been determined that the laser light LA ​​has stopped being irradiated onto the cantilever 10. In other words, the control device 100 determines the state of the drive mechanism 30 at the start of observation based on the state of the drive mechanism 30 when it has been determined that the laser light LA ​​has been irradiated onto the cantilever 10 and the state of the drive mechanism 30 when it has been determined that the laser light LA ​​has stopped being irradiated onto the cantilever 10.

[0126] The control device 100 may set the position A of the laser light source 22 when it is determined that the laser light LA ​​has been irradiated onto the cantilever 10 as the position of the laser light source 22 at the start of observation.

[0127] [Path taken by spot s1 when adjustment process S300 is executed] An example of a path that the spot s1 (irradiation position) follows as a result of the adjustment process S300 will be described with reference to Fig. 13. Fig. 13 is a diagram showing an example of a path that the spot s1 follows as a result of the adjustment process S300.

[0128] For example, in the example shown in FIG. 13, since area D is located in direction M toward the target position G, the control device 100 controls the driving mechanism 30 to move the spot s1 along direction N to avoid area D (S308, S310 in FIG. 11).

[0129] When the control device 100 continues to control the driving mechanism 30 so that the spot s1 moves along the direction N (S306 to S312 in FIG. 11), the spot s1 will be positioned at a position where it does not pass through the area D even if it is moved toward the target position G.

[0130] When the control device 100 determines that the spot s1 can be moved toward the target position G without passing through the area D (YES in S306 in FIG. 11), the control device 100 moves the spot s1 along the direction O, for example.

[0131] In this way, by executing the adjustment process S300 shown in FIG. 11, the control device 100 can align the irradiation position with the target position (the tip of the cantilever 10) without the laser light LA ​​passing through the region D where the laser light LA ​​is diffusely reflected.

[0132] [Variations of specific processing] In the above embodiment, the spot s1 is moved with respect to the irradiation surface by moving the laser light source 22. Note that the initial position of the laser light LA ​​may be specified by moving the mirror 522, which is the irradiation surface, to move the spot s1 relatively with respect to the irradiation surface.

[0133] In this case, in the identification process S100, the control device 100 may determine that the identified position of the spot s1 is correct if the position of the spot s1 does not change when the mirror 522, which is the irradiation surface, is moved.

[0134] Furthermore, a state in which the laser beam LA is not diffusely reflected can be approximated to a state in which the position of the spot s1 does not move even if the mirror 522 is moved. Therefore, the control device 100 may execute, as the identification process S100, a process of searching for a positional relationship between the mirror 522 and the spot s1 such that the position of the spot s1 does not move even if the mirror 522 is moved.

[0135] That is, the control device 100 may move the irradiation surface in a predetermined direction, and when the position of the spot s1 specified based on the image before the movement changes, determine that the position of the specified spot s1 does not correspond to the irradiation position. Also, the control device 100 may move the irradiation surface in a predetermined direction, and when the position of the spot s1 specified based on the image before the movement does not change, determine that the position of the specified spot s1 corresponds to the irradiation position.

[0136] In addition, even if the control device 100 moves the irradiation surface in a predetermined direction and the position of the spot s1 identified based on the image before the movement does not change, it may further move the irradiation surface a predetermined distance and determine that the position of the spot s1 identified based on the image corresponds to the irradiation position based on the fact that the position of the spot s1 identified based on the image does not change while the irradiation surface is being moved.

[0137] [Modification of the area to avoid passage of the laser beam LA] In the above embodiment, the area to be avoided is area D, which indicates a location where the laser light LA ​​is diffusely reflected. Note that the control device 100 may set an area wider than area D as an area to be avoided by the laser light LA.

[0138] As described above, when moving the position of the laser light source 22 by driving a motor such as the driving mechanism 30, it is difficult to move the laser light source 22 in nm to μm units. Therefore, even if the laser light LA ​​is moved so as to avoid the region D, depending on the accuracy of the driving mechanism 30, there is a risk that the laser light LA ​​may pass through the region D.

[0139] Therefore, by setting an area wider than the area D as an area where the laser light LA ​​is to be prevented from passing, the laser light LA ​​can be prevented from passing through the area D even if the accuracy of the driving mechanism 30 is not high.

[0140] That is, when the position of the region D is specified, the control device 100 may move the irradiation position relatively to the irradiation surface so as to pass through a position a predetermined distance away from the specified position.

[0141] [Other variations] (How the process is carried out) In the above embodiment, a configuration example has been shown in which the processor 120 executes a program to perform the position adjustment process S1 of the laser light source 22 and the position adjustment process S2 of the detector 28, but some or all of the functions provided by these processes may be implemented using a dedicated hardware circuit (e.g., an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array)).

[0142] (Modifications of the drive mechanism 30) In the above embodiment, the driving mechanism 30 changes the irradiation position of the laser light LA ​​by moving the position of the laser light source 22. The irradiation position of the laser light LA ​​may be changed by adjusting the position of the beam splitter 24. Also, the laser light LA ​​may be irradiated onto the cantilever 10 by moving the position of the cantilever 10.

[0143] (Modification of Adjustment Process) In the above embodiment, the control device 100 performed feedback control based on the image captured by the imaging unit 60 until the position of the spot s1 was sufficiently close to the target position. The control device 100 may generate a path from the initial position of the spot s1 to the target position so as to avoid the region D, move the irradiation position along the generated path, and then execute the fine adjustment process S330. That is, the control device 100 may control the driving mechanism 30 to move the spot s1 along the generated path until the position of the spot s1 is sufficiently close to the target position, and perform feedback control on the driving mechanism 30 based on the image after the spot s1 is sufficiently close to the target position. In this way, the time required for the adjustment process can be shortened.

[0144] In addition, the control device 100 may differentiate the distance by which the position of the spot s1 is moved in one control until it becomes sufficiently close to the target position (the distance by which it is moved in S316) from the distance by which the position of the spot s1 is moved in one control after it becomes sufficiently close to the target position (the distance by which it is moved in S338).

[0145] In this case, the control device 100 may make the distance moved in S316 longer than the distance moved in S338. In this way, the time required for the adjustment process can be shortened.

[0146] That is, the control device 100 may perform a first control when the distance between the irradiation position and the cantilever is greater than a predetermined distance, and may perform a second control with higher accuracy than the first control when the distance between the irradiation position and the cantilever is less than the predetermined distance. The first control may be, for example, a control to move the irradiation position along a path formed so as to avoid the region D, or may be a control to move the irradiation position based on an image so as to avoid the region D. The second control may be, for example, a control to move the irradiation position based on an image.

[0147] [Aspects] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0148] (Item 1) A scanning probe microscope according to one embodiment includes a cantilever, a light source that emits laser light toward the cantilever, a moving mechanism that moves the irradiation position of the laser light on an irradiation surface of the laser light relative to the irradiation surface, an imaging unit that includes the cantilever in its imaging range, and a control device. The control device identifies a position at which the laser light will be diffusely reflected based on an image captured by the imaging unit, and causes the moving mechanism to move the irradiation position relative to the irradiation surface so that the laser light is irradiated onto the cantilever while avoiding the position at which the laser light will be diffusely reflected.

[0149] According to the scanning probe microscope described in paragraph 1, the irradiation position is adjusted to avoid positions that cause diffuse reflection of the laser light, thereby preventing diffuse reflection of the laser light from adversely affecting the process of adjusting the optical axis of the laser light in the scanning probe microscope.

[0150] (Item 2) In the scanning probe microscope described in item 1, the control device may specify the position at which the laser light is diffusely reflected, based on an image captured with the light source turned off.

[0151] According to the scanning probe microscope described in item 2, the reflected light of the laser light is not captured in the image, and therefore the process of identifying the position where the laser light is diffusely reflected is simplified.

[0152] (Item 3) The scanning probe microscope according to item 1 or 2 may further include a mirror provided in a sample holder for holding a sample. In this case, the control device may specify a position at which the laser light is diffusely reflected within a range of an area corresponding to the mirror in an image captured by the imaging unit.

[0153] According to the scanning probe microscope described in item 3, the region of interest for identifying the position at which the laser light is to be diffusely reflected is narrowed, and therefore the process of identifying the position at which the laser light is to be diffusely reflected is simplified.

[0154] (Item 4) In the scanning probe microscope described in any one of items 1 to 3, the control device may continue to move the irradiation position relative to the irradiation surface when the cantilever is irradiated with laser light by moving the irradiation position relative to the irradiation surface until the cantilever is no longer irradiated with laser light. In this case, the control device may determine the state of the moving mechanism at the start of observation based on the state of the moving mechanism when the cantilever is irradiated with laser light and the state of the moving mechanism when the cantilever is no longer irradiated with laser light by continuing to move the irradiation position relative to the irradiation surface.

[0155] According to the scanning probe microscope described in item 4, even if the adjustment precision of the irradiation position by the moving mechanism is not sufficiently high, the conditions at the start of observation (the conditions of the moving mechanism that can irradiate the cantilever with laser light) can be determined early.

[0156] (Item 5) A scanning probe microscope according to one embodiment includes a cantilever, a light source that emits laser light toward the cantilever, a moving mechanism that moves the irradiation position of the laser light on a surface irradiated with the laser light relative to the irradiated surface, an imaging unit that includes at least a part of the irradiated surface in its imaging range, and a control device. The control device may specify a position of a spot of the laser light formed on the irradiated surface based on an image captured by the imaging unit, and specify the irradiation position depending on whether the position of the spot specified based on an image obtained by moving the irradiation position by the moving mechanism is a position predicted by the movement of the irradiation position.

[0157] According to the scanning probe microscope described in paragraph 5, the irradiation position of the laser light LA ​​can be specified taking into account the diffuse reflection of the laser light, thereby preventing the diffuse reflection of the laser light from adversely affecting the process of adjusting the optical axis of the laser light in the scanning probe microscope.

[0158] (Item 6) In the scanning probe microscope described in Item 5, the movement mechanism may move the irradiation position by moving the light source. In this case, the control device may move the irradiation position in a predetermined direction, and when the position of the spot identified based on an image captured before the movement does not move in the predetermined direction, determine that the identified position of the spot does not correspond to the irradiation position.

[0159] According to the scanning probe microscope described in paragraph 6, the irradiation position of the laser light LA ​​can be specified taking into account the diffuse reflection of the laser light, so that the diffuse reflection of the laser light can be prevented from adversely affecting the process of adjusting the optical axis of the laser light in the scanning probe microscope.

[0160] (Item 7) In the scanning probe microscope described in item 6, the control device may determine that the position of the spot identified based on an image captured before the movement has moved in a predetermined direction, so that the identified position of the spot corresponds to the irradiation position.

[0161] According to the scanning probe microscope described in paragraph 7, the irradiation position of the laser light LA ​​can be specified taking into account the diffuse reflection of the laser light, so that the diffuse reflection of the laser light can be prevented from adversely affecting the process of adjusting the optical axis of the laser light in the scanning probe microscope.

[0162] (Item 8) In the scanning probe microscope described in item 6, the control device may move the irradiation position in a predetermined direction by a predetermined distance when the position of the spot identified based on the image captured before the movement moves in a predetermined direction, and when the position of the spot identified on the image captured by the imaging unit moves in the predetermined direction in accordance with the movement of the irradiation position, determine that the position of the identified spot corresponds to the irradiation position.

[0163] The scanning probe microscope described in paragraph 8 can prevent erroneous identification of the irradiation position due to the coincidence of the movement direction of the spot position detected on the image with the actual movement direction. Furthermore, the scanning probe microscope described in paragraph 8 ensures that the laser light is not diffusely reflected over a predetermined distance to which the irradiation position is moved.

[0164] (Item 9) In one aspect of a method for adjusting an optical axis in a scanning probe microscope, the scanning probe microscope includes a cantilever, a light source that emits laser light toward the cantilever, a moving mechanism that moves an irradiation position of the laser light on an irradiation surface of the laser light relatively to the irradiation surface, and an imaging unit that includes the cantilever in its imaging range. The optical axis adjustment method includes a step of identifying a position at which the laser light is diffusely reflected based on an image captured by the imaging unit, and a step of moving the irradiation position relatively to the irradiation surface by the moving mechanism so that the laser light is irradiated to the cantilever while avoiding the position at which the laser light is diffusely reflected.

[0165] According to the method for adjusting the position of a scanning probe microscope described in item 9, the irradiation position is adjusted to avoid positions that cause diffuse reflection of the laser light, thereby preventing diffuse reflection of the laser light from adversely affecting the process of adjusting the optical axis of the laser light in the scanning probe microscope.

[0166] (Item 10) In an optical axis adjustment method for a scanning probe microscope according to one aspect, the scanning probe microscope includes a cantilever, a light source that emits laser light toward the cantilever, a moving mechanism that moves the irradiation position of the laser light on a surface irradiated with the laser light relative to the irradiated surface, and an imaging unit that includes at least a part of the irradiated surface in its imaging range. The optical axis adjustment method includes the steps of: specifying a position of a spot of the laser light formed on the irradiated surface based on an image captured by the imaging unit; and specifying the irradiation position depending on whether the position of the spot specified based on an image obtained by moving the irradiation position by the moving mechanism is a position predicted by the movement of the irradiation position.

[0167] According to the position adjustment method for a scanning probe microscope described in paragraph 10, the irradiation position of the laser light LA ​​can be specified taking into account the diffuse reflection of the laser light, thereby preventing the diffuse reflection of the laser light from adversely affecting the process of adjusting the optical axis of the laser light in the scanning probe microscope. [Explanation of symbols]

[0168] 1 scanning probe microscope, 10 cantilever, 12 probe, 14 holder, 20 optical system, 22 laser light source, 24 beam splitter, 26 reflecting mirror, 28 detector, 30, 40 driving mechanism, 50 scanner, 52 sample holder, 54 base, 60 imaging unit, 100 control unit, 120 processor, 140 memory, 160 display unit, 180 input unit, 280 light receiving surface, 520 stub-type attachment, 522 mirror, 524 magnet, 540 sample stage, LA laser light, P image, S sample.

Claims

1. A cantilever and A mirror provided on a sample holder for holding a sample; a light source that emits a laser beam toward the cantilever and the mirror; a driving mechanism that moves an irradiation position of the laser light on an irradiation surface of the laser light relative to the irradiation surface; an imaging unit that captures an image including the cantilever and the mirror in an imaging range; a control device; The control device includes: irradiating the laser light from the light source to an initial position on the mirror, and identifying the position of the irradiated spot based on an image captured by the imaging unit; Identifying at least one of the positions of irregularities on the surface of the mirror and substances adhering to the surface of the mirror based on the image captured by the imaging unit; and a scanning probe microscope, wherein while irradiating the laser light, the irradiation position is moved from the initial position to a position on the cantilever by the driving mechanism, avoiding the at least one position, based on the irradiation position of the laser light identified by the image captured by the imaging unit.

2. The scanning probe microscope according to claim 1 , wherein the control device identifies the at least one position based on an image captured by the imaging section with the light source turned off.

3. 3. The scanning probe microscope according to claim 1, wherein the control device specifies the at least one position within a range of an area corresponding to the mirror in the image captured by the imaging section.

4. 4. The scanning probe microscope according to claim 1, wherein the control device identifies a pixel having a pixel value greater than pixel values ​​of other pixels within a region corresponding to the mirror in the image captured by the imaging unit as the pixel corresponding to the at least one position.

5. The control device includes: when it is determined that the laser light has been irradiated to the cantilever because the spot of the laser light cannot be identified on the image captured by the imaging unit by moving the irradiation position relative to the irradiation surface, the irradiation position is continued to be moved relative to the irradiation surface until it is determined that the laser light has stopped being irradiated to the cantilever because the spot of the laser light can be identified again on the image captured by the imaging unit; 5. A scanning probe microscope according to claim 1, wherein the irradiation position at the start of observation is determined based on the irradiation position when it is determined that the laser light has been irradiated onto the cantilever, and the irradiation position when it is determined that the laser light is no longer irradiated onto the cantilever by continuing to move the irradiation position relative to the irradiation surface.

6. 1. A method for adjusting an optical axis in a scanning probe microscope, comprising the steps of: The scanning probe microscope comprises: A cantilever and A mirror provided on a sample holder for holding a sample; a light source that emits a laser beam toward the cantilever and the mirror; a driving mechanism that moves an irradiation position of the laser light on an irradiation surface of the laser light relative to the irradiation surface; an imaging unit configured to capture an image including the cantilever and the mirror in an imaging range, The optical axis adjustment method includes: a step of irradiating the laser light from the light source to an initial position on the mirror, and identifying the irradiated spot position based on an image captured by the imaging unit; Identifying at least one of the positions of irregularities on the surface of the mirror and substances attached to the surface of the mirror based on the image captured by the imaging unit; and moving the irradiation position of the laser light from the initial position to a position on the cantilever by the driving mechanism, while avoiding the at least one position, based on the irradiation position of the laser light identified by the image captured by the imaging unit, while the laser light is being irradiated.

Images