An objective lens, a method for its structural design, and a transmission electron microscope

Abstract

The present invention discloses an objective lens, a structural design method thereof, and a transmission electron microscope. The structural design method of the objective lens includes: establishing a geometric model of the objective lens and performing mesh division on the objective lens parameter information; inputting preset objective lens parameter information into the geometric model of the objective lens; determining magnetic field state information according to the objective lens parameter information and the preset objective lens parameter information; providing optical information of the objective lens; adjusting the pole piece size state information of the objective lens according to the optical information and the magnetic field state information; and obtaining the optical information and the magnetic field state information again according to the pole piece size state information to obtain an objective lens structure that meets preset conditions. By performing simulation data analysis on the objective lens structure and adjusting the pole piece size state information, the distribution of the magnetic induction intensity in the objective lens is affected, thereby ensuring the use effect of the objective lens.

Description

Technical Field

[0001] The present invention relates to the field of electron microscopy technology, and in particular, to an objective lens, a structural design method thereof, and a transmission electron microscope. Background Art

[0002] The observation of microscopic substances by the human eye is limited. An electron microscope is an important instrument that can observe smaller substances. The electron microscope uses an electron beam as the illumination light source, and magnetic lenses are widely used in electron microscopy technology. As a device for electrons, magnetic lenses are used to achieve optical magnification. As a magnetic lens, the objective lens is one of the key components that determine the resolution of the electron microscope. The objective lens is composed of an upper pole piece, a lower pole piece, a coil, and a magnetic circuit. When a suitable current is applied to the coil, a magnetic flux is generated in the magnetic circuit. Due to the gap between the upper and lower pole pieces, the magnetic flux diffuses from the end face of the pole piece to the central axis to form a rotationally symmetric magnetic field. Therefore, the electron beam passes through the central axis and converges and forms an image under the action of the magnetic field force. However, since both the pole piece and the magnetic circuit are made of magnetic materials, there is a phenomenon of magnetic saturation, and the magnetic flux generated by the current excitation cannot increase infinitely. Therefore, scientifically designing the structure of the pole piece and ensuring that a larger magnetic flux can pass through the magnetic circuit as much as possible is crucial for improving the magnification and resolution. Summary of the Invention

[0003] The present invention provides an objective lens, a structural design method thereof, and a transmission electron microscope to increase the maximum magnetic flux that can pass through the magnetic circuit of the objective lens and ensure a reasonable distribution of the magnetic induction intensity in the objective lens.

[0004] In a first aspect, an embodiment of the present invention provides a structural design method for an objective lens, including:

[0005] Establishing a geometric model of the objective lens and performing mesh division on the objective lens parameter information;

[0006] Inputting preset objective lens parameter information into the geometric model of the objective lens;

[0007] Determining magnetic field state information according to the objective lens parameter information and the preset objective lens parameter information;

[0008] Providing optical information of the objective lens;

[0009] Adjusting the pole piece size state information of the objective lens according to the optical information and the magnetic field state information;

[0010] Obtaining the optical information and the magnetic field state information again according to the pole piece size state information to obtain an objective lens structure that meets the preset conditions.

[0011] Optionally, performing mesh division on the objective lens parameter information includes:

[0012] Perform mesh generation on the ferromagnetic material structure information and the coil structure information.

[0013] Optionally, input preset objective lens parameter information into the objective lens geometric model, including:

[0014] Input the magnetization curve information of the preset ferromagnetic material and the excitation information of the preset coil into the objective lens geometric model.

[0015] Optionally, determine the magnetic field state information according to the objective lens parameter information and the preset objective lens parameter information, including:

[0016] Determine the magnetic induction intensity distribution information and the on-axis magnetic field distribution information according to the objective lens parameter information and the preset objective lens parameter information.

[0017] Optionally, after determining the magnetic induction intensity distribution information and the on-axis magnetic field distribution information according to the objective lens parameter information and the preset objective lens parameter information, further include:

[0018] Obtain the magnetic induction intensity distribution nephogram of the objective lens pole shoe and the magnetic circuit according to the magnetic induction intensity distribution information and the on-axis magnetic field distribution information.

[0019] Optionally, before adjusting the pole shoe size state information of the objective lens according to the optical information and the magnetic field state information, further include:

[0020] Determine whether to increase the saturation excitation value according to the optical information and the magnetic field state information;

[0021] If so, adjust the pole shoe size state information of the objective lens, rebuild the objective lens geometric model, and perform mesh generation on the objective lens parameter information;

[0022] If not, end the operation.

[0023] Optionally, adjust the pole shoe size state information of the objective lens according to the optical information and the magnetic field state information, including:

[0024] Adjust the pole shoe width state information and the pole shoe taper state information of the objective lens according to the optical information and the magnetic field state information.

[0025] Optionally, provide the optical information of the objective lens, including:

[0026] Provide the focal length information, magnification information, spherical aberration coefficient information, and chromatic aberration coefficient information of the objective lens;

[0027] Determine the resolution information according to the focal length information, the magnification information, the spherical aberration coefficient information, and the chromatic aberration coefficient information.

[0028] Second aspect, an embodiment of the present invention provides an objective lens, including the structural design method of the objective lens described in any one of the first aspect.

[0029] Third aspect, an embodiment of the present invention provides a transmission electron microscope, including the objective lens described in the second aspect.

[0030] The technical solution of the embodiment of the present invention, by providing a structural design method of an objective lens, includes: establishing a geometric model of the objective lens and performing grid division on the parameter information of the objective lens; inputting preset parameter information of the objective lens into the geometric model of the objective lens; determining magnetic field state information according to the parameter information of the objective lens and the preset parameter information of the objective lens; providing optical information of the objective lens; adjusting the pole piece size state information of the objective lens according to the optical information and the magnetic field state information; obtaining the optical information and the magnetic field state information again according to the pole piece size state information to obtain an objective lens structure that meets the preset conditions. By performing simulation data analysis on the objective lens structure, adjusting the pole piece size state information affects the distribution of the magnetic induction intensity in the objective lens, thereby ensuring the use effect of the objective lens.

[0031] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a schematic flow chart of a structural design method of an objective lens provided by an embodiment of the present invention;

[0034] Figure 2 It is a schematic diagram of the objective lens structure in the prior art;

[0035] Figure 3 It is a schematic diagram of the pole piece structure in the prior art;

[0036] Figure 4 It is a schematic diagram of a pole piece structure provided by an embodiment of the present invention;

[0037] Figure 5 It is a schematic flow chart of another structural design method of an objective lens provided by an embodiment of the present invention;

[0038] Figure 6 It is a schematic flow chart of another structural design method of an objective lens provided by an embodiment of the present invention;

[0039] Figure 7 It is a schematic flow chart of another method for designing the structure of the objective lens provided by the embodiment of the present invention;

[0040] Figure 8 It is a schematic flow chart of another method for designing the structure of the objective lens provided by the embodiment of the present invention;

[0041] Figure 9 It is a schematic flow chart of another method for designing the structure of the objective lens provided by the embodiment of the present invention;

[0042] Figure 10 It is a distribution diagram of the magnetic induction intensity on the pole shoe and magnetic circuit and an on-axis magnetic field diagram of the objective lens under 8000 AT excitation in the prior art;

[0043] Figure 11 It is a distribution diagram of the magnetic induction intensity on the pole shoe and magnetic circuit and an on-axis magnetic field diagram of the objective lens under 10000 AT excitation in the prior art;

[0044] Figure 12 It is a distribution diagram of the magnetic induction intensity on the pole shoe and magnetic circuit and an on-axis magnetic field diagram of an objective lens provided by the embodiment of the present invention under 8000 AT excitation;

[0045] Figure 13 It is a distribution diagram of the magnetic induction intensity on the pole shoe and magnetic circuit and an on-axis magnetic field diagram of an objective lens provided by the embodiment of the present invention under 10000 AT excitation;

[0046] Figure 14 It is a schematic flow chart of another method for designing the structure of the objective lens provided by the embodiment of the present invention;

[0047] Figure 15 It is a schematic flow chart of another method for designing the structure of the objective lens provided by the embodiment of the present invention;

[0048] Figure 16 It is a schematic diagram of the structure of an objective lens provided by the embodiment of the present invention;

[0049] Figure 17 It is a schematic diagram of the structure of a transmission electron microscope provided by the embodiment of the present invention. Detailed implementation manners

[0050] To enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0051] It should be noted that the terms "including" and "having" in the description and claims of the present invention and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0052] Figure 1 It is a schematic flow chart of a method for designing the structure of an objective lens provided by an embodiment of the present invention. This embodiment is applicable to the situation of optimizing the objective lens structure. This method can be executed by a device for designing the structure of the objective lens, and the device for designing the structure of the objective lens can be implemented in the form of hardware and / or software as Figure 1 shown. The method includes:

[0053] S101, Establish an objective lens geometric model and perform mesh division on the objective lens parameter information.

[0054] Among them, for the objective lens geometric model setting of the objective lens, mainly a three-dimensional modeling method is used, and mesh division is performed on the formed objective lens geometric model for relevant objective lens parameter information. The size of each mesh does not exceed 1 mm, thereby ensuring the accuracy of the objective lens structure design. Since the main components of the objective lens are the objective lens pole shoes, coils and magnetic circuits, the objective lens parameter information is mainly the information related to the above structures.

[0055] S102, Input preset objective lens parameter information into the objective lens geometric model.

[0056] Among them, the preset objective lens parameter information is the relevant parameter information of the magnetism and excitation of the objective lens to be optimized currently, such as the ferromagnetic material parameter information of the objective lens components and the excitation state information of the coil, which is convenient for obtaining the optical properties of the objective lens subsequently.

[0057] S103, Determine the magnetic field state information according to the objective lens parameter information and the preset objective lens parameter information.

[0058] Among them, according to the objective lens parameter information and the preset objective lens parameter information, a set of mutually related nonlinear algebraic equations of magnetic vector potential at adjacent grid points are derived by adopting the finite element method (FEM), and these nonlinear algebraic equations of magnetic vector potential are iteratively solved by Newton's method, so as to obtain the magnetic field state information in the objective lens. The magnetic field state information may include magnetic induction intensity distribution information and magnetic vector potential distribution information, etc.

[0059] S104, providing optical information of the objective lens.

[0060] Among them, the optical information of the objective lens can be determined by the light source signal output into the objective lens. The light source signal is usually an electron beam. The electron trajectory equation is calculated by the initial energy of the electron beam. The electron trajectory equation is also the paraxial trajectory equation. Then, the optical information of the objective lens is obtained with the help of numerical calculation of the paraxial trajectory equation.

[0061] S105, adjusting the pole shoe size status information of the objective lens according to the optical information and the magnetic field status information.

[0062] Among them, the uneven distribution of the magnetic field in the structure near the end face of the current objective lens pole shoe can be determined based on the optical information and the magnetic field state information, thereby affecting the optical properties of the objective lens. In the traditional objective lens structure, the upper pole shoe in the objective lens pole shoe has a large cone angle and a large end face, while the lower pole shoe has a small cone angle and a small end face, resulting in the upper pole shoe allowing The saturation magnetic flux is greater than the saturation magnetic flux allowed by the lower pole shoe. Therefore, when the lower pole shoe is saturated, it is easy to generate stray fields and widen the on-axis magnetic field, thereby limiting the imaging ability of the objective lens. Therefore, by reasonably adjusting the state information of the pole shoe size of the objective lens, that is, adjusting the shape of the pole shoe in the objective lens, the distribution of the magnetic field state in the objective lens is affected, thereby affecting the subsequent imaging effect of the objective lens.

[0063] S106, acquiring optical information and magnetic field state information again according to the pole shoe size state information to obtain an objective lens structure that meets preset conditions.

[0064] Among them, since the pole shoe size status information is adjusted, that is, the shape of the pole shoe is adjusted, it is necessary to re-judge the performance of the objective lens, and it is necessary to repeat S101 to S105 to ensure that the adjusted objective lens structure meets the preset conditions. The preset conditions are that the magnetic induction intensity in the structure near the end face of the current objective lens pole shoe is evenly distributed, and the optical information of the objective lens such as resolution and magnification are improved, thereby improving the electronic imaging effect of the transmission electron microscope using the objective lens. Figure 2 is a schematic diagram of the objective lens structure in the prior art, Figure 3 is a schematic diagram of the structure of a pole shoe in the prior art, Figure 4 A schematic diagram of the structure of a pole shoe provided by an embodiment of the present invention is shown in FIG. Figure 2 , Figure 3 and Figure 4As shown in the figure, the objective lens includes an upper pole piece 1, a lower pole piece 2, a coil 3, a magnetic circuit 4, and an optical axis 5. Based on the objective lens structure in the prior art, without changing the magnetic circuit and the S and D parameters in the pole pieces, where S represents the gap between the upper and lower pole pieces, D represents the inner hole diameter of the pole piece, D1 represents the inner hole diameter of the upper pole piece, and D2 represents the inner hole diameter of the lower pole piece, mainly adjust the shape of the pole piece, such as Figure 4 As shown in the figure, adjust the shape of the lower pole piece 2, and then it can achieve improving the saturation excitation, magnification, and resolution to improve the imaging effect of the objective lens.

[0065] The embodiment of the present invention discloses determining the magnetic field state information by establishing an objective lens geometric model according to the objective lens parameter information and the preset objective lens parameter information; at the same time, providing the optical information of the objective lens; adjusting the pole piece size state information of the objective lens according to the optical information and the magnetic field state information; repeating the above operations again according to the pole piece size state information to obtain the optical information and the magnetic field state information, and then obtaining the objective lens structure that meets the preset conditions. So as to perform simulation data analysis on the objective lens structure, adjusting the pole piece size state information affects the distribution of the magnetic induction intensity in the objective lens, and then ensuring the use effect of the objective lens.

[0066] Optionally, Figure 5 It is a schematic flow structure diagram of another objective lens structure design method provided by the embodiment of the present invention. The method includes:

[0067] S201, establish an objective lens geometric model, and perform mesh division on the ferromagnetic material structure information and the coil structure information.

[0068] Among them, since the main components in the objective lens structure are the objective lens pole pieces, the coil, and the magnetic circuit, and the upper pole piece, the lower pole piece, and the magnetic circuit in the objective lens pole pieces are all composed of ferromagnetic materials, therefore, during the optimization process of the objective lens structure, it is necessary to perform mesh division on the ferromagnetic material structure information and the coil structure information, which is further convenient for analyzing the performance of the objective lens structure, and then ensuring the use effect of the objective lens.

[0069] S202, input the preset objective lens parameter information into the objective lens geometric model.

[0070] S203, determine the magnetic field state information according to the ferromagnetic material structure information, the coil structure information, and the preset objective lens parameter information.

[0071] Among them, since the objective lens geometric model is divided into multiple meshes according to the ferromagnetic material structure information and the coil structure information, the preset objective lens parameter information related to the ferromagnetic material structure information and the coil structure information is given to the objective lens geometric model, and then ensuring the accurate acquisition of the magnetic field state information of the objective lens.

[0072] S204, provide the optical information of the objective lens.

[0073] S205. Adjust the pole piece size status information of the objective lens according to the optical information and the magnetic field status information.

[0074] S206. Obtain the optical information and the magnetic field status information again according to the pole piece size status information to obtain an objective lens structure that meets the preset conditions.

[0075] Among them, since the pole piece size status information is adjusted, that is, the shape of the pole piece is adjusted, at this time, it is necessary to judge the performance of the objective lens again, and it is necessary to repeat S201-S205 again to ensure that the adjusted objective lens structure meets the preset conditions, that is, the magnetic induction intensity distribution in the current objective lens structure is uniform, and the optical information of the objective lens such as the resolution and magnification is improved, thereby improving the electron imaging effect of the transmission electron microscope using the objective lens.

[0076] The embodiment of the present invention discloses determining the magnetic field status information by establishing an objective lens geometric model according to the ferromagnetic material information, coil information and preset objective lens parameter information; at the same time providing the optical information of the objective lens; adjusting the pole piece size status information of the objective lens according to the optical information and the magnetic field status information; repeating the above operations again according to the pole piece size status information to obtain the optical information and the magnetic field status information, so as to obtain an objective lens structure that meets the preset conditions. So as to perform simulation data analysis on the objective lens structure, adjust the pole piece size status information to affect the magnetic induction intensity distribution in the objective lens, and thus ensure the use effect of the objective lens.

[0077] Optionally, Figure 6 is a schematic flow structure diagram of another objective lens structure design method provided by the embodiment of the present invention, as Figure 6 shown, the method includes:

[0078] S301. Establish an objective lens geometric model and perform mesh division on the ferromagnetic material structure information and the coil structure information.

[0079] S302. Input the magnetization curve information of the preset ferromagnetic material and the excitation information of the preset coil into the objective lens geometric model.

[0080] Among them, since the magnetization curve information (B-H curve) of the preset ferromagnetic material related to the objective lens and the excitation information (AT) of the corresponding preset coil are input into the objective lens geometric model, that is, the magnetization curves of different types of ferromagnetic materials applied to the objective lens are stored, and the current excitation corresponding to the coil in the current objective lens is selected to ensure that magnetic flux is generated in the magnetic circuit of the objective lens, thereby generating a magnetic field.

[0081] S303. Determine the magnetic field status information according to the ferromagnetic material structure information, the coil structure information, the magnetization curve information of the preset ferromagnetic material and the excitation information of the preset coil.

[0082] Among them, according to the magnetization curve information of the preset ferromagnetic material and the excitation information of the preset coil in the corresponding input objective lens geometric model, the magnetic field state information of the current corresponding objective lens structure is obtained, so as to reflect the magnetic induction distribution in the current objective lens structure, which is convenient for subsequent optimization design of the objective lens structure.

[0083] S304, provide the optical information of the objective lens.

[0084] S305, adjust the pole piece size state information of the objective lens according to the optical information and the magnetic field state information.

[0085] S306, obtain the optical information and the magnetic field state information again according to the pole piece size state information, so as to obtain an objective lens structure that meets the preset conditions.

[0086] Among them, since the pole piece size state information is adjusted, that is, the shape of the pole piece is adjusted. At this time, it is necessary to judge the performance of the objective lens again, and it is necessary to repeat S301-S305 again, so as to ensure that the adjusted objective lens structure meets the preset conditions, that is, the magnetic induction intensity distribution in the current objective lens structure is uniform, and the optical information such as resolution and magnification is improved, so as to improve the electron imaging effect of the transmission electron microscope using the objective lens.

[0087] The embodiment of the present invention discloses determining the magnetic field state information by establishing an objective lens geometric model according to the ferromagnetic material structure information, the coil structure information, the magnetization curve information of the preset ferromagnetic material and the excitation information of the preset coil; at the same time, providing the optical information of the objective lens; adjusting the pole piece size state information of the objective lens according to the optical information and the magnetic field state information; repeating the above operations again according to the pole piece size state information to obtain the optical information and the magnetic field state information, so as to obtain an objective lens structure that meets the preset conditions. So as to perform simulation data analysis on the objective lens structure, adjust the pole piece size state information to affect the magnetic induction intensity distribution in the objective lens, and thus ensure the use effect of the objective lens.

[0088] Optionally, Figure 7 is a schematic flow chart of another objective lens structure design method provided by the embodiment of the present invention, as Figure 7 shown, the method includes:

[0089] S401, establish an objective lens geometric model and perform mesh division on the objective lens parameter information.

[0090] S402, input the preset objective lens parameter information into the objective lens geometric model.

[0091] S403, determine the magnetic induction intensity distribution information and the on-axis magnetic field distribution information according to the objective lens parameter information and the preset objective lens parameter information.

[0092] Among them, since the materials forming the pole shoes and the magnetic circuit in the objective lens structure are all obtained by processing magnetic materials, and at the same time, when a preset current is applied to the coil for excitation, magnetic flux will be generated in the magnetic circuit. Therefore, in the working state of the objective lens, the main information reflecting the performance of the objective lens structure is the magnetic induction intensity distribution information and the on-axis magnetic field distribution information. The on-axis magnetic field distribution information is reflected as the magnetic field distribution on the central axis, i.e., the optical axis, of the objective lens structure.

[0093] S404. Provide the optical information of the objective lens.

[0094] S405. Adjust the pole shoe size status information of the objective lens according to the optical information, magnetic induction intensity distribution information, and on-axis magnetic field distribution information.

[0095] Among them, the pole shoe size status information of the objective lens is adaptively adjusted according to the obtained optical information, magnetic induction intensity distribution information, and on-axis magnetic field distribution information, thereby ensuring the imaging effect of the objective lens.

[0096] S406. Obtain the optical information, magnetic induction intensity distribution information, and on-axis magnetic field distribution information again according to the pole shoe size status information to obtain an objective lens structure that meets the preset conditions.

[0097] Among them, since the pole shoe size status information has been adjusted, it is necessary to judge the performance of the objective lens again at this time. It is necessary to repeat S401 - S405 again to obtain the optical information, magnetic induction intensity distribution information, and on-axis magnetic field distribution information again, thereby ensuring that the magnetic induction intensity distribution of the adjusted objective lens structure is uniform, and the optical information such as resolution and magnification is improved, and further improving the electron imaging effect of the transmission electron microscope using the objective lens.

[0098] The embodiment of the present invention discloses that by establishing a geometric model of the objective lens, the magnetic induction intensity distribution information and the on-axis magnetic field distribution information are determined according to the objective lens parameter information and the preset objective lens parameter information; at the same time, the optical information of the objective lens is provided; the pole shoe size status information of the objective lens is adjusted according to the optical information, magnetic induction intensity distribution information, and on-axis magnetic field distribution information; the above operations are repeated again according to the pole shoe size status information to obtain the optical information and the magnetic field status information, thereby obtaining an objective lens structure that meets the preset conditions. So as to perform simulation data analysis on the objective lens structure, adjust the pole shoe size status information to affect the magnetic induction intensity distribution in the objective lens, and thus ensure the use effect of the objective lens.

[0099] Optionally, Figure 8 is a schematic flowchart of another objective lens structure design method provided by the embodiment of the present invention, as Figure 8 shown. This method includes:

[0100] S501. Establish a geometric model of the objective lens and perform mesh division on the objective lens parameter information.

[0101] S502. Input the preset objective lens parameter information into the geometric model of the objective lens.

[0102] S503. Determine the magnetic induction intensity distribution information and the on-axis magnetic field distribution information according to the objective lens parameter information and the preset objective lens parameter information.

[0103] S504. Obtain the magnetic induction intensity distribution nephogram of the objective lens pole shoes and the magnetic circuit according to the magnetic induction intensity distribution information and the on-axis magnetic field distribution information.

[0104] Among them, draw the magnetic induction intensity distribution nephogram according to the obtained magnetic induction intensity distribution information and the on-axis magnetic field distribution information. This magnetic induction intensity distribution nephogram shows the magnetic induction distribution of the objective lens pole shoes and the magnetic circuit in the objective lens structure. The parts to be optimized in the objective lens structure can be determined according to the magnetic induction intensity distribution nephogram, which is convenient for improving the subsequent use effect of the objective lens.

[0105] S505. Provide the optical information of the objective lens.

[0106] S506. Adjust the pole shoe size status information of the objective lens according to the optical information and the magnetic induction intensity distribution nephogram of the objective lens pole shoes and the magnetic circuit.

[0107] Among them, the optical properties of the current objective lens structure are reflected through the optical information to judge whether the current objective lens structure is in a good imaging state. At the same time, view the magnetic induction distribution state according to the magnetic induction intensity distribution nephogram, and then adjust the pole shoe size status information of the objective lens, so as to ensure the imaging performance of the objective lens.

[0108] S507. Obtain the optical information, magnetic induction intensity distribution information and on-axis magnetic field distribution information again according to the pole shoe size status information to obtain an objective lens structure that meets the preset conditions.

[0109] Among them, since the pole shoe size status information has been adjusted, it is necessary to judge the performance of the objective lens again at this time. It is necessary to repeat S501 - S506 again to obtain the optical information, magnetic induction intensity distribution information and on-axis magnetic field distribution information again, so as to ensure that the magnetic induction intensity distribution of the adjusted objective lens structure is uniform, and the optical information such as the resolution and magnification of the objective lens is improved, thereby improving the electron imaging effect of the transmission electron microscope using the objective lens.

[0110] An embodiment of the present invention discloses that by establishing an objective lens geometric model, the magnetic induction intensity distribution information and the on-axis magnetic field distribution information are determined according to the objective lens parameter information and the preset objective lens parameter information; and according to the magnetic induction intensity distribution information and the on-axis magnetic field distribution information, a cloud map of the magnetic induction intensity distribution in the objective lens pole shoe and the magnetic circuit is drawn, and at the same time, the optical information of the objective lens is provided; the pole shoe size state information of the objective lens is adjusted according to the optical information and the cloud map of the magnetic induction intensity distribution in the objective lens pole shoe and the magnetic circuit; the above operations are repeated again according to the pole shoe size state information to obtain the optical information and the magnetic field state information, and then an objective lens structure that meets the preset conditions is obtained. So as to perform simulation data analysis on the objective lens structure, adjust the pole shoe size state information to affect the magnetic induction intensity distribution in the objective lens, and then ensure the use effect of the objective lens.

[0111] Optionally, Figure 9 is a schematic flow structure diagram of another objective lens structure design method provided by an embodiment of the present invention, as Figure 9 shown, the method includes:

[0112] S601, establish an objective lens geometric model and perform grid division on the objective lens parameter information.

[0113] S602, input the preset objective lens parameter information into the objective lens geometric model.

[0114] S603, determine the magnetic field state information according to the objective lens parameter information and the preset objective lens parameter information.

[0115] S604, provide the optical information of the objective lens.

[0116] S605, determine whether to increase the saturation excitation value according to the optical information and the magnetic field state information.

[0117] Among them, generally, the focal length of the objective lens can be shortened by increasing the excitation to reduce the aberration coefficient, so as to obtain higher resolution, and the shorter focal length is also more conducive to obtaining higher magnification. The pole shoe and the magnetic circuit in the objective lens structure are both processed from magnetic materials, and there is a magnetic saturation phenomenon. The magnetic flux generated by the current excitation cannot increase infinitely. Therefore, scientifically designing the pole shoe structure and ensuring that a larger magnetic flux can pass through the magnetic circuit as much as possible is crucial for improving the magnification and resolution. Whether to appropriately increase the saturation excitation value is driven according to the current optical information and the magnetic field state information. If so, continue the operation; if not, stop the operation and complete the objective lens structure that meets the preset conditions.

[0118] S606, if so, adjust the pole shoe size state information of the objective lens and repeat steps S601 to S606.

[0119] Among them, the magnetic field state information can reflect the distribution state of the magnetic induction intensity in the objective lens structure. If there is a position with a strong magnetic induction intensity in a certain pole piece, adaptively adjust the size state information of the pole piece, so as to ensure that the magnetic induction intensity distribution in the pole piece is as uniform as possible, and ensure the imaging effect of the objective lens.

[0120] S607, if not, end the operation.

[0121] Among them, by way of example, Figure 10 is the distribution of the magnetic induction intensity on the pole piece and the magnetic circuit and the axial magnetic field distribution diagram of the objective lens under 8000 AT excitation in the prior art. Figure 11 is the distribution of the magnetic induction intensity on the pole piece and the magnetic circuit and the axial magnetic field distribution diagram of the objective lens under 10000 AT excitation in the prior art. Figure 12 is the distribution of the magnetic induction intensity on the pole piece and the magnetic circuit and the axial magnetic field distribution diagram of an objective lens provided by an embodiment of the present invention under 8000 AT excitation. Figure 13 is the distribution of the magnetic induction intensity on the pole piece and the magnetic circuit and the axial magnetic field distribution diagram of an objective lens provided by an embodiment of the present invention under 10000 AT excitation. Table 1 is the optical information table before and after the adjustment of the objective lens.

[0122] Table 1 Optical information table before and after the adjustment of the objective lens

[0123]

[0124] As Figure 10 、 Figure 11 、 Figure 12 、 Figure 13 and shown in Table 1, it can be seen that in the prior art, although the excitation is increased, it leads to a decrease in the focal length, a decrease in the spherical aberration coefficient, a decrease in the chromatic aberration coefficient, and an improvement in the resolution, and the magnification does not increase significantly. This may result in the overall magnification not meeting the observation requirements in the application of the transmission electron microscope. At this time, by adjusting the size state information of the pole piece, it can be seen that under 8000 AT excitation, the magnetic induction intensity on the pole piece structure of the present application is lower, but the optical properties of the objective lens are equivalent to those of the objective lens in the prior art. This means that the objective lens structure in the present application can also increase the excitation, while if the excitation of the objective lens structure in the prior art is increased, there will be a broadening of the rear field of the magnetic field caused by the magnetic saturation effect, and this broadening will limit the further increase of the magnification of the objective lens. The saturation excitation in the present application can be increased to 10000 AT. After the increase, it is obvious that the axial magnetic field increases significantly, which leads to a decrease in the focal length, a decrease in the spherical aberration coefficient and the chromatic aberration coefficient, a higher theoretical resolution, and a higher magnification, effectively improving the imaging of the objective lens. Moreover, after increasing the excitation, it is still possible to ensure that the magnetic field is concentrated in a very small range without magnetic field broadening, obtaining a magnification significantly higher than that of the prior art, and other optical properties are also better than those of the prior art.

[0125] An embodiment of the present invention discloses determining magnetic field state information by establishing an objective lens geometric model and based on objective lens parameter information and preset objective lens parameter information; meanwhile, providing optical information of the objective lens; determining whether to increase the saturation excitation value according to the optical information and the magnetic field state information, and then adjusting the pole shoe size state information of the objective lens; repeating the above operations again according to the pole shoe size state information to obtain the optical information and the magnetic field state information, so as to obtain an objective lens structure that meets the preset conditions. By performing simulation data analysis on the objective lens structure, after increasing the saturation excitation, adjusting the pole shoe size state information affects the magnetic induction intensity distribution in the objective lens and the optical properties of the objective lens, thereby ensuring the imaging effect of the objective lens.

[0126] Optionally, Figure 14 is a schematic flow structure diagram of another method for designing the structure of an objective lens provided by an embodiment of the present invention, as Figure 14 shown, the method includes:

[0127] S701, establish an objective lens geometric model and perform mesh division on the objective lens parameter information.

[0128] S702, input preset objective lens parameter information into the objective lens geometric model.

[0129] S703, determine the magnetic field state information according to the objective lens parameter information and the preset objective lens parameter information.

[0130] S704, provide the optical information of the objective lens.

[0131] S705, adjust the pole shoe width state information and the pole shoe taper state information of the objective lens according to the optical information and the magnetic field state information.

[0132] Among them, according to the optical properties of the objective lens reflected by the optical information and the distribution state of the magnetic induction intensity in the objective lens reflected by the magnetic field state information, the pole shoe width state information and the pole shoe taper state information in the objective lens are correspondingly adjusted. Exemplarily, the width of the pole shoe is adaptively increased at the position where the magnetic induction intensity is strong and the pole shoe taper is adaptively adjusted, so as to ensure that the magnetic induction intensity distribution in the pole shoe is as uniform as possible, and the magnetic field does not appear too large or too small, thereby ensuring the imaging effect of the objective lens.

[0133] S706, obtain the optical information and the magnetic field state information again according to the pole shoe width state information and the pole shoe taper state information to obtain an objective lens structure that meets the preset conditions.

[0134] Among them, since the pole shoe width status information and the pole shoe taper status information are adjusted, it is necessary to judge the performance of the objective lens again at this time. It is necessary to repeat S701-S705 again to obtain the optical information, the magnetic induction intensity distribution information, and the on-axis magnetic field distribution information again, so as to ensure that the magnetic induction intensity distribution of the adjusted objective lens structure is uniform, and the optical information of the objective lens such as the resolution and magnification is improved, thereby improving the electron imaging effect of the transmission electron microscope using the objective lens.

[0135] The embodiment of the present invention discloses determining the magnetic field status information by establishing an objective lens geometric model according to the objective lens parameter information and the preset objective lens parameter information; at the same time, providing the optical information of the objective lens; adjusting the pole shoe width status information and the pole shoe taper status information of the objective lens according to the optical information and the magnetic field status information of the objective lens; repeating the above operations again according to the pole shoe size status information to obtain the optical information and the magnetic field status information of the objective lens, so as to obtain an objective lens structure that meets the preset conditions. So as to perform simulation data analysis on the objective lens structure, adjust the pole shoe width status information and the pole shoe taper status information to affect the magnetic induction intensity distribution in the objective lens, thereby ensuring the use effect of the objective lens.

[0136] Optionally, Figure 15 is a schematic flow structure diagram of another objective lens structure design method provided by the embodiment of the present invention, as Figure 15 shown, the method includes:

[0137] S801, establish an objective lens geometric model and perform grid division on the objective lens parameter information.

[0138] S802, input the preset objective lens parameter information into the objective lens geometric model.

[0139] S803, determine the magnetic field status information according to the objective lens parameter information and the preset objective lens parameter information.

[0140] S804, provide the focal length information, magnification information, spherical aberration coefficient information, and chromatic aberration coefficient information of the objective lens.

[0141] Among them, according to the initial energy information of the electron beam input into the objective lens, the electron trajectory equation is determined, and then the optical properties of the objective lens are numerically calculated according to the electron trajectory equation, that is, the focal length information, magnification information, spherical aberration coefficient information, and chromatic aberration coefficient information of the objective lens are obtained. If the electron acceleration voltage is 200 kV and the image plane position is fixed at about 153 mm below the lower pole shoe end face, find the object plane under the specified excitation, so as to calculate parameters such as the focal length, magnification, and object-side aberration coefficient of the objective lens. During the adjustment process of the objective lens structure, as the saturation excitation increases, the focal length, spherical aberration coefficient, and chromatic aberration coefficient of the objective lens become smaller, and the magnification increases, thereby improving the imaging effect of the objective lens.

[0142] S805. Determine the resolution information based on the focal length information, magnification information, spherical aberration coefficient information, and chromatic aberration coefficient information.

[0143] Among them, the resolution information of the theoretical points of the objective lens can be determined according to the optical properties of the objective lens, and then it can be judged whether the current objective lens structure meets the preset conditions, ensuring the imaging effect of the objective lens. The calculation of the resolution of the theoretical points can be through the formula δ th =0.66C S 1 / 4 λ 3 / 4 , δ th is the resolution of the theoretical points, C S is the spherical aberration coefficient, and λ is the electron wave with relativistic correction. Furthermore, the imaging performance of the objective lens can be judged according to the resolution of the objective lens structure.

[0144] S806. Adjust the pole piece size status information of the objective lens according to the focal length information, magnification information, spherical aberration coefficient information, chromatic aberration coefficient information, resolution information, and magnetic field status information.

[0145] S807. Obtain the focal length information, magnification information, spherical aberration coefficient information, chromatic aberration coefficient information, and magnetic field status information again according to the pole piece size status information to obtain an objective lens structure that meets the preset conditions.

[0146] Among them, since the pole piece width status information and the pole piece taper status information have been adjusted, it is necessary to judge the performance of the objective lens again at this time. It is necessary to repeat S801 - S806 again to obtain the focal length information, magnification information, spherical aberration coefficient information, chromatic aberration coefficient information, magnetic induction intensity distribution information, and on-axis magnetic field distribution information again, so as to ensure that the magnetic induction intensity distribution of the adjusted objective lens structure is uniform, and the optical information of the objective lens such as resolution and magnification is improved, thereby improving the electron imaging effect of the transmission electron microscope using the objective lens.

[0147] The embodiments of the present invention disclose that by establishing a geometric model of the objective lens, determining the magnetic field status information according to the objective lens parameter information and the preset objective lens parameter information, and at the same time providing the focal length information, magnification information, spherical aberration coefficient information, and chromatic aberration coefficient information of the objective lens, adjusting the pole piece size status information of the objective lens according to the focal length information, magnification information, spherical aberration coefficient information, chromatic aberration coefficient information, and magnetic field status information; repeating the above operations again according to the pole piece size status information to obtain the focal length information, magnification information, spherical aberration coefficient information, chromatic aberration coefficient information, and magnetic field status information, so as to obtain an objective lens structure that meets the preset conditions. In order to perform simulation data analysis on the objective lens structure, adjusting the pole piece size status information affects the magnetic induction intensity distribution in the objective lens, thereby ensuring the use effect of the objective lens.

[0148] Figure 16A schematic structural diagram of an objective lens provided by an embodiment of the present invention. The structure of this objective lens is designed by the objective lens structure design method described in any one of the above embodiments. The objective lens 100 has high resolution and magnification, and can improve the use effect of the objective lens.

[0149] Figure 17 A schematic structural diagram of a transmission electron microscope provided by an embodiment of the present invention. The transmission electron microscope 200 includes the objective lens 100 described in the above embodiments.

[0150] It should be noted that since the transmission electron microscope provided in this embodiment includes an objective lens as provided by an embodiment of the present invention, and it has the same or corresponding beneficial effects as the objective lens, no further description will be given here.

[0151] The above specific implementation manners do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A structural design method for an objective lens, characterized in that, Including: Establish an objective lens geometric model and perform mesh division on the objective lens parameter information, where the objective lens parameter information includes ferromagnetic material structure information and coil structure information; Input preset objective lens parameter information into the objective lens geometric model, where the preset objective lens parameter information includes magnetization curve information of a preset ferromagnetic material and excitation information of a preset coil; Determine magnetic field state information by using the finite element method according to the objective lens parameter information and the preset objective lens parameter information, where the magnetic field state information includes magnetic induction intensity distribution information and on-axis magnetic field distribution information; Provide the optical information of the objective lens; Adjust the pole piece size state information of the objective lens according to the optical information and the magnetic field state information; obtain the optical information and the magnetic field state information again according to the pole piece size state information to obtain an objective lens structure that meets the preset conditions, where the preset condition is that the magnetic induction intensity distribution in the pole piece of the objective lens is uniform; Among them, adjusting the pole piece size state information of the objective lens according to the optical information and the magnetic field state information includes: Determine the imaging state of the objective lens according to the optical information; Determine the magnetic induction distribution state according to the magnetic field state information; Adjust the pole piece size state information of the objective lens according to the imaging state and the magnetic induction distribution state.

2. The structural design method of the objective lens according to claim 1, characterized in that, Performing mesh division on the objective lens parameter information includes: Performing mesh division on the ferromagnetic material structure information and the coil structure information.

3. The structural design method of the objective lens according to claim 1, characterized in that Inputting the preset objective lens parameter information into the objective lens geometric model includes: Inputting the magnetization curve information of the preset ferromagnetic material and the excitation information of the preset coil into the objective lens geometric model.

4. The structural design method of the objective lens according to claim 1, characterized in that Determining the magnetic field state information according to the objective lens parameter information and the preset objective lens parameter information includes: Determining the magnetic induction intensity distribution information and the on-axis magnetic field distribution information according to the objective lens parameter information and the preset objective lens parameter information.

5. The structural design method of the objective lens according to claim 4, characterized in that, After determining the magnetic induction intensity distribution information and the on-axis magnetic field distribution information according to the objective lens parameter information and the preset objective lens parameter information, it further includes: Obtain the magnetic induction intensity distribution nephogram of the objective lens pole piece and the magnetic circuit according to the magnetic induction intensity distribution information and the on-axis magnetic field distribution information.

6. The structural design method of the objective lens according to claim 1, characterized in that, Before adjusting the pole piece size state information of the objective lens according to the optical information and the magnetic field state information, it further includes: Determine whether to increase the saturation excitation value according to the optical information and the magnetic field state information; If so, adjust the pole piece size state information of the objective lens, re-establish the objective lens geometric model, and perform mesh division on the objective lens parameter information; If not, end the operation.

7. The structural design method of the objective lens according to claim 1, characterized in that Adjusting the pole piece size state information of the objective lens according to the optical information and the magnetic field state information includes: Adjust the pole piece width state information and the pole piece taper state information of the objective lens according to the optical information and the magnetic field state information.

8. The structural design method of the objective lens according to claim 1, characterized in that, Providing the optical information of the objective lens includes: Provide the focal length information, magnification information, spherical aberration coefficient information, and chromatic aberration coefficient information of the objective lens; Determine the resolution information according to the focal length information, the magnification information, the spherical aberration coefficient information, and the chromatic aberration coefficient information.

9. An objective lens, characterized in that, Including the structural design method of the objective lens according to any one of claims 1-8.

10. A transmission electron microscope, characterized in that, Comprising the objective lens described in claim 9.

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