Scanning probe microscope

Abstract

The utility model provides a scanning probe microscope, comprising a light beam conversion lens group configured to convert a light beam emitted by a light source into a Bessel light beam; a probe arm of the probe at least partially reflects the Bessel beam, and the light reflecting position of the probe arm is located in the focal depth range of the Bessel beam; and the position sensitive detector is configured to be capable of forming a corresponding signal form according to the position of the received light beam reflected by the probe arm. The probe is located in the focal depth range of the Bessel beam, so that the light path adjustment difficulty is reduced, and the environmental requirements of the scanning probe microscope are reduced.

Description

Technical Field

[0001] This invention belongs to the field of scanning probe technology, specifically relating to scanning probe microscopes. Background Technology

[0002] Scanning probe microscopy (SPM) measures the surface shape of a sample by bringing a probe close to or into contact with the sample surface. Its applications are wide-ranging, including the surface structure, physical properties, chemical reactions, nanofabrication, and information storage of materials such as conductors, semiconductors, insulators, biological materials, organic materials, and nanomaterials. Most existing SPMs employ a method known as the optical lever method to detect the analyte. Specifically, the optical lever method involves illuminating the probe's cantilever with a laser beam and detecting changes in the position of the reflected laser light through a detector. This allows the detection of the probe's position and / or orientation, thereby obtaining the position of the probe tip and / or the interaction force between the tip and the analyte.

[0003] The probes in existing scanning probe microscopes are typically extremely small, requiring the light beam to be reduced to a very small spot size to illuminate the probe cantilever. This necessitates that the optical elements through which the light incident on the probe arm passes have a high numerical aperture. However, this high numerical aperture results in a short depth of focus, meaning the probe arm can only converge the light beam into a clear spot and form an optical lever for detection within a very small depth of focus range. This makes optical path adjustment extremely inconvenient, impacting the efficiency of the scanning probe microscope.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of this utility model, and therefore may contain information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0005] To address the technical problem of inconvenient optical path adjustment in existing technologies, this application first provides a scanning probe microscope, comprising: a beam conversion mirror assembly configured to convert a light beam emitted from a light source into a Bessel beam; a probe, wherein the probe arm at least partially reflects the Bessel beam, and the reflection position of the probe arm is located within the focal depth range of the Bessel beam; and a position-sensitive detector configured to generate a corresponding signal based on the position of the light beam reflected by the probe arm.

[0006] According to one embodiment of this application, the light beam emitted by the light source is a Gaussian beam.

[0007] According to one embodiment of this application, the beam conversion mirror assembly includes at least a conical mirror.

[0008] According to one embodiment of this application, the beam conversion mirror group further includes a first converging lens and a second converging lens, which are disposed between the conical mirror and the probe arm.

[0009] According to one embodiment of this application, the beam conversion mirror assembly further includes a beam adjustment lens, which is disposed between the conical mirror and the light source.

[0010] According to one embodiment of this application, the tip of the probe extends toward the reflective side away from the probe arm.

[0011] According to one embodiment of this application, the Bessel beam and the probe arm form a preset angle, which is configured to enable the position-sensitive detector to receive the beam reflected by the probe arm.

[0012] According to one embodiment of this application, the light source is a laser light source or a light-emitting diode.

[0013] The scanning probe microscope provided by this invention has at least the following beneficial effects: By placing the probe within the focal depth range of the Bessel beam, a clear and fine light spot is formed on the probe arm. The beam can be focused on the probe arm without fine position adjustments, reducing the difficulty of optical path adjustment and greatly simplifying the optical path adjustment process of the scanning probe microscope. The larger focal depth range allows for greater probe movement within this range. When detecting a analyte, if the probe encounters a sudden change in the surface morphology of the analyte, the beam can be continuously irradiated onto the probe arm without adjusting the optical path when adjusting the probe height. This increases the detectable height range of the scanning probe microscope and expands its applicability. Furthermore, even with interference from dust or foreign objects within the focal depth range, the beam can still irradiate the probe arm, significantly reducing the environmental requirements of the scanning probe microscope. Especially for underwater scanning probe microscopes, there are no special requirements regarding the cleanliness of the liquid containing the analyte, greatly facilitating the detection of the analyte. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of one embodiment of a scanning probe microscope provided in this application.

[0015] Figure 2 This is a schematic diagram of another embodiment of a scanning probe microscope provided in this application.

[0016] Figure 3 This is a schematic diagram of the beam near the probe arm.

[0017] Figure 4 This is a schematic diagram of the focal depth range of the probe arm and the beam. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise ratios, and are only used to conveniently and clearly assist in illustrating the purpose of the embodiments of this utility model.

[0019] This application provides a scanning probe microscope. Light emitted from a light source 1 passes through a beam conversion mirror assembly 2 and illuminates a probe 3. The probe 3 reflects at least a portion of the beam to a position-sensitive detector 4. The position or state of the probe 3 is calculated based on the signal output by the position-sensitive detector 4, thereby calculating the interaction force between the probe 3 and the object under test 5, and enabling the detection of the surface characteristics of the object under test 5. The light source 1 emits a beam to illuminate the probe 3. The beam conversion mirror assembly 2 is configured to convert the light source into a Bessel beam. After the beam L is converted into a Bessel beam L by the beam conversion mirror assembly 2, it forms an ultra-long depth of focus D. Within the depth of focus D, the beam L can converge into a small spot. The reflective position of the probe arm 3 is located within the depth of focus D of the Bessel beam L, so that the probe arm 31 of the probe 3 can at least partially reflect the Bessel beam L. The position-sensitive detector 4 is configured to generate a corresponding signal based on the position of the beam L' reflected by the probe arm 3.

[0020] When probe 3 is within the focal depth range D of Bessel beam L, Bessel beam L can form a small spot within the focal depth range D. The larger focal depth range D allows probe 3 to move significantly within the focal depth range D, greatly simplifying the optical path adjustment process of the scanning probe microscope and reducing the difficulty of optical path adjustment. When detecting the test object 5, when probe 3 encounters a sudden change in the surface morphology of the test object 5, the beam L can be continuously irradiated on probe arm 31 without adjusting the optical path when adjusting the height of probe 3, thereby increasing the height range of the test object 5 that can be detected by the scanning probe microscope and improving the applicability of the scanning probe microscope. At the same time, even if there is some interference from dust or foreign objects within the focal depth range D, the beam L can still irradiate probe arm 31, greatly reducing the environmental requirements of the scanning probe microscope. Especially for underwater scanning probe microscopes, there is no need to make special requirements on the cleanliness of the liquid in which the test object 5 is located, which greatly facilitates the detection of the test object 5.

[0021] In some cases, as a feasible implementation, the light beam emitted by the light source 1 is a Gaussian beam. After passing through the beam conversion mirror group 2, the Gaussian beam is converted into a Bessel beam L.

[0022] The beam conversion mirror group 2 is configured to convert the incident beam L into a Bessel beam L. Specifically, the beam conversion mirror group 2 can be a conical mirror, a spatial light modulator, a resonant cavity, or a combination of an annular slit and a lens, as long as it can convert the beam L into a Bessel beam L.

[0023] As a feasible approach, the beam conversion mirror assembly 2 includes at least a conical mirror 21. The beam L emitted by the light source 1 passes through the conical mirror 21 to form a Bessel beam L, which then illuminates the probe arm 31. (See also...) Figure 1 This illustrates a feasible implementation in which the beam L, after passing through the conical mirror 21, forms a Bessel beam L and a diffraction-free beam region A. It should be noted that, typically, the extent of the diffraction-free beam region of the Bessel beam L along the axis of beam L corresponds to the focal depth D of the Bessel beam L. The probe arm 31 is located within the diffraction-free region A.

[0024] The light beam L', reflected by probe arm 31, illuminates position-sensitive detector 4. Position-sensitive detector 4 outputs a corresponding signal based on the position of the received light beam L' on it. When the position of probe 3 changes, the position of light beam L' on position-sensitive detector 4 will also change, causing a matching change in the output signal of position-sensitive detector 4, which is then used to analyze the position of probe 3.

[0025] Due to the converging characteristics of the Bessel beam L, the beam L' reflected by the probe arm 31 is transmitted to the position-sensitive detector 4 in a generally divergent manner. Accordingly, in some cases, at least two illumination positions or illumination areas can be formed on the position-sensitive detector 4, and in some cases, a generally annular illumination area can be formed on the position-sensitive detector 4.

[0026] The position-sensitive detector 4 can be a semiconductor position-sensitive detector, a four-quadrant detector, a position-sensitive photomultiplier tube, or an image sensor, as long as its output signal can respond to the position of the light shining on it.

[0027] In some cases, the beam conversion mirror assembly 2 further includes a first converging lens 221 and a second converging lens 222, which are disposed in the optical path between the conical mirror 21 and the probe arm 31. The beam L is adjusted by the first converging lens 221 and the second converging lens 222 to adjust the focal depth, spot size, and other parameters of the beam L illuminating the probe arm 31. Alternatively, the axes of the first converging lens 221, the second converging lens 222, and the conical mirror 21 can be configured to be coaxial with the beam L.

[0028] Please see Figure 2 This illustrates a feasible implementation in which the light beam L emitted by the light source 1 forms a Bessel beam L after passing through the conical lens 21. The Bessel beam L then passes through a first converging lens 221 and a second converging lens 222 before illuminating the probe arm 31. In this way, the focal depth range A2 of the Bessel beam L can be moved and / or varied by adjusting the first converging lens 221 and the second converging lens 222, thereby meeting the detection requirements of the scanning probe microscope under different usage conditions.

[0029] It is understandable that when the first converging lens 221 and the second converging lens 222 are arranged in the optical path between the conical mirror 21 and the probe arm 31, two non-diffraction regions A1 and A2 can be formed. One non-diffraction region A1 is formed near the conical mirror 21, and the other non-diffraction region A2 is formed near the probe arm 31. In use, the non-diffraction region A2 near the probe arm 31 can be positioned within the area of ​​the reflective surface 311 of the probe arm 31.

[0030] In some cases, a beam adjustment lens can be provided between the conical mirror 21 and the light source 1 to adjust the beam L, thereby adjusting the focal depth range and / or focal depth position of the beam L illuminating the probe arm 31.

[0031] Please see Figure 1 , Figure 2 The tip 32 of the probe 3 extends away from the reflective side of the probe arm 31, so that the optical path and the object under test 5 are respectively on both sides of the probe 3, so as to avoid mutual interference between them.

[0032] Please see Figure 1 , Figure 2The Bessel beam L forms a preset angle with the probe arm 31. This preset angle is configured to allow the position-sensitive detector 4 to receive the beam L reflected from the probe arm 31. The specific setting of the preset angle can be either a direction perpendicular to the object 5 to form the corresponding preset angle, or a direction inclined to the object 5 to form the corresponding preset angle. The specific size of the preset angle can be adjusted according to the detection needs and the specific structure of the scanning probe microscope, which will not be elaborated further here.

[0033] For light source 1, it can be a laser light source or a light-emitting diode, to match different application requirements.

[0034] The surface characteristics of the object 5 are detected using the aforementioned scanning probe microscope. During use, at least one of the following components—light source 1, beam conversion mirror group 2, probe 3, and position-sensitive detector 4—is adjusted so that the reflective surface 311 of the probe arm 31 is illuminated by the beam L and located within the focal depth D of the Bessel beam L. Specifically, the relative positions of the light source 1, beam conversion mirror group 2, probe 3, and position-sensitive detector 4 can be adjusted so that the beam L, after being reflected by the probe 3, illuminates the position-sensitive detector 4, enabling the position-sensitive detector 4 to output a corresponding signal. The light source 1 and beam conversion mirror group 2 can be adjusted to at least adjust the position and focal depth D of the non-diffraction region of the Bessel beam L.

[0035] By adjusting at least one of the light source 1, beam conversion mirror group 2, probe 3, and position-sensitive detector 4, the reflective surface 311 of the probe arm 31 is positioned within the focal depth range D of the Bessel beam L, thereby enabling the position-sensitive detector 4 to receive the beam L whose position changes in response to the position change of the probe tip 32. Based on this, the surface characteristics of the object under test 5 can be calculated by analyzing the signal output by the position-sensitive detector 4.

[0036] It is understandable that the detection of the surface characteristics of the test object 5 can include surface morphology, mechanical properties, electrical properties, magnetic properties, thermal properties, chemical properties, molecular properties, biological properties, piezoelectric properties, etc. Correspondingly, for the detection of some properties, it is necessary to make adaptive adjustments to the scanning probe microscope, such as using a matching probe 3, or setting up corresponding structures in the support device that carries the test object 5.

[0037] The scanning probe microscope provided in this application has extremely low requirements for the adjustment precision of the optical path. The convergence position of the beam L on the probe arm 31 has a large range, and the user can quickly complete the adjustment of the optical path. Even if there is some interference from dust or foreign objects in the depth of focus range D or the non-diffraction region A of the Bessel beam L, the beam L can still illuminate the probe arm 31. It can keep the optical path of the beam L required for detection from being interfered with even in environments with low cleanliness, thereby enhancing the applicability of the scanning probe microscope.

[0038] In some cases, the scanning probe microscope provided in this application allows the reflective surface 311 of the probe arm 31 to be positioned within the non-diffraction region of the Bessel beam L, resulting in higher energy concentration of the beam L and maintaining sufficient intensity in the liquid. Furthermore, the non-diffraction region of the Bessel beam L allows for the presence of some interfering substances without affecting the beam L's illumination of the probe arm 31, and impurities in the liquid do not affect the beam L's illumination of the probe arm 31. Therefore, the scanning probe microscope provided in this application can more effectively detect the analyte 5 in a liquid environment. Specifically, during detection, the surface of the analyte 5 is positioned below the liquid surface. In some cases, the position of the reflected Bessel beam L from the probe arm 31 can also be positioned below the liquid surface.

[0039] The basic principles, main features, and advantages of this utility model have been shown and described above. Therefore, the above description is only an embodiment of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are only the principles of this utility model. Without departing from the spirit and scope of this utility model, this utility model also includes various equivalent changes and modifications, all of which will fall within the scope of this utility model as claimed.

Claims

1. A scanning probe microscope, characterized in that, include: The beam conversion mirror assembly is configured to convert the light beam emitted by the light source into a Bessel beam; A probe, wherein the probe arm at least partially reflects the Bessel beam, and the reflection position of the probe arm is located within the depth of focus of the Bessel beam; A position-sensitive detector is configured to generate a corresponding signal based on the position of the beam reflected from the probe arm.

2. A scanning probe microscope as described in claim 1, characterized in that: The light beam emitted by the light source is a Gaussian beam.

3. A scanning probe microscope as described in claim 1, characterized in that: The beam conversion mirror assembly includes at least a conical mirror.

4. A scanning probe microscope as described in claim 3, characterized in that: The beam conversion mirror group also includes a first converging lens and a second converging lens, which are disposed between the conical mirror and the probe arm.

5. A scanning probe microscope as described in claim 3, characterized in that: The beam conversion mirror assembly also includes a beam adjustment lens, which is disposed between the conical mirror and the light source.

6. A scanning probe microscope as described in claim 1, characterized in that: The tip of the probe extends toward the reflective side away from the probe arm.

7. A scanning probe microscope as described in claim 1, characterized in that: The Bessel beam and the probe arm are at a preset angle, which is configured to enable the position-sensitive detector to receive the beam reflected by the probe arm.

8. A scanning probe microscope as described in claim 1, characterized in that: The light source is a laser light source or a light-emitting diode.

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