Modularized atomic force microscope with coaxial imaging

Abstract

The invention discloses a modular atomic force microscope with coaxial imaging. The atomic force microscope comprises a modularized coaxial imaging unit and a microscope main body based on a laser head, and the coaxial imaging unit is fixed on the microscope main body and is coaxially arranged with a laser scanning light path. According to the invention, coaxial linkage of scanning and imaging can be realized, the adjustment process is simplified, the equipment is compact in size and convenient to disassemble, assemble and maintain, and the practicability and suitability of the miniaturized atomic force microscope are improved.

Description

Technical Field

[0001] This invention belongs to the field of atomic force microscopy technology, specifically relating to a modular atomic force microscope with coaxial imaging, which is particularly suitable for miniaturized atomic force microscopes based on laser heads. Background Technology

[0002] Atomic force microscopy (AFM) is one of the core tools in nanotechnology research. Laser-based AFMs, in particular, have gained widespread attention and application due to their low cost and compact size. In 2011, Lee et al. built the first AFM system based on a commercial DVD laser head. Since then, related technologies have been continuously optimized and upgraded, but the optical imaging problem during the scanning process has remained unresolved. Currently, most researchers use external microscopes for imaging assistance. This method not only suffers from cumbersome optical path adjustments and difficulty in precisely adapting to the AFM, but also significantly increases the overall size of the equipment, contradicting the miniaturized and portable design principles of this type of AFM and limiting its application in more scenarios. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a modular atomic force microscope with coaxial imaging to solve the technical problems of difficult adjustment and increased size caused by the reliance on external microscope imaging in laser-head-based atomic force microscopes.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A modular atomic force microscope with coaxial imaging includes a modular coaxial imaging unit and a laser-head-based microscope body. The coaxial imaging unit is fixed on the microscope body and arranged coaxially with the laser scanning optical path.

[0005] Furthermore, the coaxial imaging unit includes a light source module and an imaging module. The light source module includes an LED light source and a light source lens, which are not located on the optical axis of the laser scanning optical path. The imaging module includes an image sensor, a first imaging lens, a first semi-transparent and semi-reflective beam splitter, and a second imaging lens, which are placed sequentially along the optical axis. The center of each component of the imaging module coincides with the axis of the laser scanning optical path.

[0006] Furthermore, the center of the light source lens intersects perpendicularly with the axis of the laser scanning optical path, and is located in the middle position between the LED light source and the first semi-transparent and semi-reflective beam splitter.

[0007] Furthermore, the first semi-transparent and semi-reflective beam splitter is fixed in the positioning groove at a 45° angle to the axis of the laser scanning optical path.

[0008] Furthermore, the first imaging lens and the second imaging lens adopt a cemented doublet lens structure.

[0009] Furthermore, the main body of the laser head-based microscope includes a laser head, which comprises a second semi-transparent and semi-reflective beam splitter, a collimating lens, an objective lens, a third semi-transparent and semi-reflective beam splitter, a photodetector, and a laser diode.

[0010] Furthermore, the coaxial imaging unit is fixed to the assembly platform of the microscope body via a detachable connection structure.

[0011] Furthermore, the detachable connection structure includes a fine-tuning knob for adjusting the distance between the coaxial imaging unit and the microscope body.

[0012] Furthermore, the detachable connection structure is a snap-on or threaded connection assembly, and the positioning surface of the connection assembly is fitted with the reference surface of the microscope body.

[0013] Furthermore, a probe fixing unit is integrated below the assembly platform of the microscope body, wherein the lower surface of the assembly platform is provided with a recess that matches the groove on the probe fixing unit; the probe fixing unit has a built-in magnet that is tightly attracted to the liner of the assembly platform.

[0014] Compared with existing technologies, the modular atomic force microscope with coaxial imaging of this invention has the following advantages: (1) By integrating the modular coaxial imaging unit with the atomic force microscope, the drawback of existing laser-head-based atomic force microscopes relying on external microscopes for imaging is solved.

[0015] (2) The modular structure is highly adaptable and easy to assemble and disassemble. The coaxial arrangement ensures imaging accuracy while greatly reducing the size of the equipment, thus retaining the core advantages of low cost and miniaturization of this type of atomic force microscope.

[0016] (3) The operation and adjustment are simple, the imaging is clear and stable, and it is suitable for various scenarios such as nanomaterial detection and microstructure observation. It has outstanding practicality and promotion value. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the optical path of the modular atomic force microscope of the present invention.

[0018] Figure 2 This is a schematic diagram of the overall system structure of the modular atomic force microscope of the present invention.

[0019] Figure 3 This is a schematic diagram of an example structure of the modular atomic force microscope of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will be further illustrated below with specific examples.

[0021] The core of this invention lies in constructing a scanning head that integrates the coaxial imaging optical path and the laser head. By using a coaxial optical path design, the optical path offset error in traditional atomic force microscopy imaging is eliminated. At the same time, the modular combination of the laser head and the imaging part improves the system's convenience and adaptability.

[0022] As shown in Figure 1, the atomic force microscope of the present invention includes a modular coaxial imaging unit and a microscope body based on a laser head. The coaxial imaging unit is fixed to the microscope body and arranged coaxially with the laser scanning optical path. The coaxial imaging unit includes a light source module and an imaging module. The light source module includes an LED light source 1-1 and a light source lens 1-2 separately disposed on one side. The LED light source 1-1 and the light source lens 1-2 are not located on the optical axis of the laser scanning optical path. The imaging module includes an image sensor 1-3, an imaging lens 1-4, a semi-transparent and semi-reflective beam splitter 1-5, and an imaging lens 1-6, arranged sequentially along the optical axis from the sample. The centers of these components all coincide with the axis of the laser scanning optical path of the atomic force microscope. All of these components are fixed to a support inside the microscope. The main body of the laser head-based microscope includes a laser head (OPU). Inside the OPU are longitudinally arranged semi-transparent and semi-reflective beam splitters 1-7, collimating lenses 1-8, objective lenses 1-9, and a semi-transparent and semi-reflective beam splitter 1-10 placed in the opposite direction on one side, a photodetector (PDIC) 1-11, and a laser diode (LD) 1-12.

[0023] In this embodiment: LED light source 1-1 is a monochromatic light source, and its power must ensure that the illumination intensity meets the requirements of microscopic imaging; the light source lens 1-2 is a fixed arrangement structure, with its lens center perpendicularly intersecting the axis of the laser scanning optical path, located in the middle position between LED light source 1-1 and semi-transparent beam splitter 1-5, ensuring the stability of the beam propagation path; the semi-transparent beam splitter 1-5 is tilted at a 45° angle to the optical path axis and fixed in the angle positioning groove of the bracket, ensuring that the tilt angle deviation of the semi-transparent beam splitter is ≤1°, and its reflective surface is precisely matched with the imaging optical path and the laser scanning optical path, ensuring the stability of the beam reflection direction; the imaging lens group (imaging lens 1-4 and imaging lens 1-6) is a combined structure, and double cemented lenses can be used to eliminate on-axis spherical aberration and chromatic aberration, and improve the beam collimation accuracy. The OPU uses a DVD laser head, which is generally suitable for various types of laser heads. When the LED light source 1-1 built into the coaxial imaging unit is activated, it emits a beam as imaging illumination light, which is perpendicularly directed towards the light source lens 1-2 inside the unit. The divergent beam emitted by the LED is refracted by the light source lens 1-2 and transformed into a parallel beam, ensuring the directionality and uniformity of the beam during propagation, thus providing a foundation for subsequent image clarity.

[0024] The parallel beam continues to propagate to the semi-transparent, semi-reflective beam splitter 1-5, which is tilted at a 45° angle to the imaging beam path and the laser scanning beam path of the atomic force microscope. At this point, the imaging beam, after being reflected by the beam splitter, changes its propagation direction by 90°, propagating downwards along the same axis (i.e., coaxial) as the laser scanning beam of the atomic force microscope, thus achieving precise beam combining of the two beam paths. The imaging beam passes through the semi-transparent, semi-reflective beam splitter 1-7 inside the laser head and is combined with the laser scanning beam. It then passes through the collimating lens 1-8 and the objective lens 1-9, and then vertically illuminates the sample surface, covering the target scanning area on the sample, completing the illumination process.

[0025] The sample surface diffusely reflects the imaging beam, and the reflected beam, carrying microscopic morphological information of the sample surface, returns along the original optical path. After passing through the laser head, it ascends to the imaging lens 1-6, is collimated, and then reaches the semi-transparent beam splitter 1-5. The reflected beam, carrying sample information, is transmitted through the beam splitter (separating from the initial incident reflection path) and continues upward to the imaging lens 1-4. The beam is then focused and precisely projected onto the photosensitive surface of the image sensor 1-3 (CCD). The image sensor 1-3 converts the optical signal into an electrical signal, which is output in real time through the data transmission interface, ultimately forming a clear optical image of the sample target area. This imaging process is synchronized with the scanning process of the atomic force microscope, achieving coaxial linkage between scanning and imaging.

[0026] The coaxial imaging unit of this invention is arranged coaxially with the laser optical path of the atomic force microscope. The coaxial imaging unit can be used as a modular unit and fixedly integrated with the microscope body based on the laser head through a detachable connection structure. It can move synchronously with the microscope body to achieve synchronous imaging of the target area during the scanning process. Figure 2 The diagram illustrates the mechanical assembly relationship of the system, focusing on the combination of the coaxial imaging unit and the laser head-based microscope body, as well as the overall structure of the microscope. The LED light source 1-1 and image sensor 1-3 are fixed to the customized optical path tube as shown in the diagram, forming the main imaging components (internal lenses are also assembled). The coaxial imaging unit is then detachably mounted to the assembly platform 2-3 of the microscope body via modular connecting components 2-2 (such as snap-fit ​​or threaded connecting components), ensuring the coaxiality of the upper and lower optical paths and enabling rapid assembly, disassembly, and positioning of the coaxial imaging unit. The positioning surface of the connecting components is tightly fitted to the reference surface of the microscope body, ensuring consistent coaxiality accuracy between the coaxial imaging unit and the optical path body after assembly and disassembly. The distance between the coaxial imaging module and the atomic force microscope body can be adjusted using the built-in fine-tuning knob 2-1, allowing for focusing at different imaging distances during use. The laser head 2-4 is located at the bottom, with a probe tightly connected to it, enabling atomic force microscopy functionality through different external scanning structures.

[0027] like Figure 3As shown, this embodiment uses a threaded support column 3-1 to support the entire system. The support column is connected to the main platform of the system via a threaded bushing, and its height can be finely adjusted to adapt to different external displacement stages. At the same time, vibration damping pads on the support column achieve a certain degree of vibration attenuation, balancing rigid support and anti-interference, and supporting quick disassembly to adapt to multiple experimental platforms. The probe fixing unit 3-2 is integrated under the assembly platform 2-3 and adopts a dual constraint design of "recessed positioning + magnetic locking": a square recess is provided on the lower surface of the platform, which precisely matches the bottom groove of the probe fixing unit 3-2 (positioning accuracy ≤0.1mm). The probe fixing unit 3-2 has a built-in neodymium iron boron strong magnet (attraction force ≥5N), which is tightly attracted to the ferromagnetic liner of the platform. Probe loading and unloading can be completed without tools, and it is compatible with standard AFM cantilever beam probes. It has the advantages of positioning stability, convenient operation and versatility, and meets the experimental needs of multiple scenarios.

[0028] Obviously, the above embodiments are merely some, not all, of the embodiments of the present invention. The above embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without inventive effort, that is, all modifications, equivalent substitutions, and improvements made within the spirit and principle of this application, fall within the scope of protection claimed by the present invention.

Claims

1. A modular atomic force microscope with coaxial imaging, characterized in that, It includes a modular coaxial imaging unit and a laser head-based microscope body. The coaxial imaging unit is fixed on the microscope body and arranged coaxially with the laser scanning optical path.

2. The modular atomic force microscope with coaxial imaging according to claim 1, characterized in that, The coaxial imaging unit includes a light source module and an imaging module. The light source module includes an LED light source and a light source lens, which are not located on the optical axis of the laser scanning optical path. The imaging module includes an image sensor, a first imaging lens, a first semi-transparent and semi-reflective beam splitter, and a second imaging lens, which are placed sequentially along the optical axis. The center of each component of the imaging module coincides with the axis of the laser scanning optical path.

3. A modular atomic force microscope with coaxial imaging according to claim 2, characterized in that, The center of the light source lens intersects perpendicularly with the axis of the laser scanning optical path and is located between the LED light source and the first semi-transparent and semi-reflective beam splitter.

4. A modular atomic force microscope with coaxial imaging according to claim 2, characterized in that, The first semi-transparent and semi-reflective beam splitter is fixed in the positioning groove at a 45° angle to the axis of the laser scanning optical path.

5. A modular atomic force microscope with coaxial imaging according to claim 2, characterized in that, The first imaging lens and the second imaging lens adopt a cemented doublet lens structure.

6. A modular atomic force microscope with coaxial imaging according to claim 1, characterized in that, The microscope body based on the laser head includes a laser head, which comprises a second semi-transparent and semi-reflective beam splitter, a collimating lens, an objective lens, a third semi-transparent and semi-reflective beam splitter, a photodetector, and a laser diode.

7. A modular atomic force microscope with coaxial imaging according to claim 1, characterized in that, The coaxial imaging unit is fixed to the assembly platform of the microscope body via a detachable connection structure.

8. A modular atomic force microscope with coaxial imaging according to claim 7, characterized in that, The detachable connection structure includes a fine-tuning knob for adjusting the distance between the coaxial imaging unit and the microscope body.

9. A modular atomic force microscope with coaxial imaging according to claim 7, characterized in that, The detachable connection structure is a snap-on or threaded connection assembly, and the positioning surface of the connection assembly is fitted with the reference surface of the microscope body.

10. A modular atomic force microscope with coaxial imaging according to claim 7, characterized in that, The microscope body has a probe fixing unit integrated below the assembly platform. The lower surface of the assembly platform has a recess that matches the groove on the probe fixing unit. The probe fixing unit has a built-in magnet that is tightly attracted to the liner of the assembly platform.

Images