CN219085927U - Rapid imaging system and transmission electron microscope - Google Patents
Rapid imaging system and transmission electron microscope Download PDFInfo
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- CN219085927U CN219085927U CN202222715104.3U CN202222715104U CN219085927U CN 219085927 U CN219085927 U CN 219085927U CN 202222715104 U CN202222715104 U CN 202222715104U CN 219085927 U CN219085927 U CN 219085927U
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- imaging system
- electron beam
- deflection
- electrostatic deflector
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Abstract
The utility model discloses a rapid imaging system and a transmission electron microscope, wherein the imaging system comprises a transmitting unit, a magnetic lens, an electrostatic deflector and an imaging unit which are sequentially and coaxially arranged along the Z-axis direction; the emission unit is used for emitting electrons; the magnetic lens is used for emitting an incident electron beam in the form of a parallel beam; the electrostatic deflector comprises a plurality of pairs of mutually parallel deflection plates, all the deflection plates are combined to form a channel for a parallel light beam to pass through, and each deflection plate is connected with a driving circuit which is used for driving the deflection plate independently and is used for changing the off-axis distance of the electron beam passing through the channel in the XY direction; the imaging unit is opposite to the channel and is used for observing the position of the electron beam spot emitted by the channel. The utility model can improve the imaging capability of the transmission electron microscope and improve the time resolution under the condition of keeping the space resolution unchanged.
Description
Technical Field
The utility model relates to the technical field of electron microscopes, in particular to a rapid imaging system and a transmission electron microscope.
Background
At present, a transmission electron microscope has been widely applied in the field of high spatial resolution imaging, and the high spatial resolution capability enables the transmission electron microscope to detect on an atomic scale, so that great achievements are obtained in important scientific research fields such as material science, physics, semiconductor science, biology and the like. And the deflector is an important component of an ultrafast camera in a transmission electron microscope imaging system, and determines the imaging quality. The image generation process is that an electron beam is emitted by an electron gun, and then an electric field or a magnetic field generated by a deflector is deflected and hits an ultrafast camera screen to generate an image.
According to electrodynamic theory, the motion state of a moving electron beam changes under different excitation sources, such as electric field deflection or magnetic field deflection. The deflector is manufactured on this principle. And the deflector may be classified into an electrostatic deflector and a magnetic deflector according to different excitation sources. Wherein, the electrostatic deflector is formed by combining a plurality of symmetrical electrodes with certain voltage applied to the center; magnetic deflectors are typically composed of rotationally symmetrical geometric magnets and energized coils. Since the electrostatic deflector is substantially affected only by the plate capacitance and the output voltage of the driving circuit, its deflection speed is faster than that of the magnetic deflector, but the time resolution capability of the existing electrostatic deflector is still limited. The deflection sensitivity of the magnetic deflector is better, and the influence of distortion is smaller; however, due to the structure of the magnetic core, the inductance of the deflector is relatively large, and it is difficult to realize high-frequency scanning.
Therefore, how to improve the high spatial resolution imaging capability of a transmission electron microscope, and to improve the time resolution capability of the transmission electron microscope while maintaining high spatial resolution, to obtain images with high spatial and temporal resolution, and to optimize an imaging system have become an important research topic of the transmission electron microscope.
Disclosure of Invention
In order to overcome the defects in the prior art, one of the purposes of the utility model is to provide a rapid imaging system.
It is a further object of the present utility model to provide a transmission electron microscope comprising a rapid imaging system.
One of the purposes of the utility model is realized by adopting the following technical scheme:
a rapid imaging system is applied to a transmission electron microscope and comprises an emission unit, a magnetic lens, an electrostatic deflector and an imaging unit which are sequentially and coaxially arranged along the Z-axis direction; the emission unit is used for emitting electrons; the magnetic lens is used for emitting an incident electron beam in the form of a parallel beam;
the electrostatic deflector comprises a plurality of pairs of mutually parallel deflection plates, all the deflection plates are combined to form a channel for a parallel light beam to pass through, and each deflection plate is connected with a driving circuit which is used for driving the deflection plate independently and is used for changing the off-axis distance of the electron beam passing through the channel in the XY direction;
the imaging unit is opposite to the channel and is used for observing the position of the electron beam spot emitted by the channel.
Further, the emission unit comprises an electron gun, a Welch cap, an anode, a converging mirror and a converging mirror diaphragm which are coaxially and sequentially distributed; the electron gun is used as an electron source for imaging; the Welch cap is used for focusing electrons; the anode is used for providing acceleration voltage to accelerate the electron beam through the optical axis; the converging mirror is used for focusing the electron beam to the focal position of the magnetic lens; the converging mirror diaphragm is used for limiting the electron dose emitted by the electron gun.
Further, the electrostatic deflector comprises two pairs of the deflection plates in parallel with each other, and the driving circuit to which each of the deflection plates is connected comprises a voltage-adjustable power supply.
Further, each voltage-adjustable power supply is provided with N voltage states, and any deflection plate is switched under the combination of N voltages, so that the whole electrostatic deflector has 4 N Different deflector plate switch states.
Further, the deflection plate is a copper plate.
Further, the electrostatic deflector is also connected with a signal generator, and the signal generator drives the electrostatic deflector according to the self-defined time sequence parameters.
Further, the timing parameters include a switching mode of the electrostatic deflector, an exposure time, and a trigger delay time.
Further, the imaging unit includes a phosphor screen facing the channel and ensuring that the electron beam will be deflected to each designated area of the phosphor screen in turn; the shooting device is arranged below the fluorescent screen and used for shooting the electron beam spots on the fluorescent screen.
Further, the signal generator is triggered by the camera to synchronize the exposure of the camera with the deflection of the electrostatic deflector.
The second purpose of the utility model is realized by adopting the following technical scheme:
a transmission electron microscope comprising a rapid imaging system as described above.
Compared with the prior art, the utility model has the beneficial effects that:
(1) Improving the time resolution
The electrostatic deflection system of the present utility model can change the electromagnetic field state multiple times at a single time node, enabling it to allocate time in a 4 x 4 subframe; namely, the deflection plates can output 4 multiplied by 4=16 images in the same unit time under the control of respective driving circuits, and the time resolution capability reaches 16 times of the original time resolution capability;
(2) The deflection system has the characteristics of high speed, high precision, programmability and no overshoot
Each deflection plate of the utility model can be controlled by a single driving circuit with 4 adjustable values, and the whole control circuit has 256 switch states, so that the deflection and scanning path of the electron beam can be accurately controlled; meanwhile, each output stage allows any one of the four direct current power supplies to be connected to the output thereof at any time, and after the switching time of the on states of the four direct current power supplies is adjusted, the overshoot phenomenon occurring when the output states are switched can be greatly eliminated.
Drawings
FIG. 1 is a schematic diagram of a fast imaging system according to the present utility model;
FIG. 2 is a cross-sectional view of an electrostatic deflector of the present utility model scanning XY along a prescribed path;
fig. 3 is a diagram showing a driving circuit configuration of the electrostatic deflector of the present utility model.
In the figure: 1. an electron gun; 2. welch cap; 3. an anode; 4. a converging mirror; 5. a converging mirror diaphragm; 6. a magnetic lens; 7. an electrostatic deflector; 8. a luminescent screen; 9. a camera; 10. an electron beam initial deflection position; 11. a deflector plate; 12. the electron beam terminates in a deflected position.
Detailed Description
The present utility model will be further described with reference to the accompanying drawings and detailed description, wherein it is to be understood that, on the premise of no conflict, the following embodiments or technical features may be arbitrarily combined to form new embodiments.
Example 1
The embodiment provides a rapid imaging system, in particular a programmable rapid electrostatic deflection structure applied to a transmission electron microscope, which comprises an emission unit, a magnetic lens 6, an electrostatic deflector 7 and an imaging unit which are sequentially arranged along the Z-axis direction; and the emission unit, the magnetic lens 6, the electrostatic deflector 7, and the imaging unit are coaxial.
The emission unit is used for emitting electrons; the emission unit in the embodiment comprises an electron gun 1, a Welch cap 2, an anode 3, a converging mirror 4 and a converging mirror diaphragm 5 which are coaxially and sequentially distributed; wherein the electron gun 1 is used as an electron source for imaging; the Welch cap 2 is used for focusing electrons; the anode 3 is used for providing acceleration voltage to accelerate the electron beam to pass through the subsequent electron optical element; the converging mirror 4 is used for focusing the electron beam to the focal position of the magnetic lens 6; the converging mirror diaphragm 5 is used to limit the electron dose emitted by the electron gun 1.
The magnetic lens 6 is disposed below the converging mirror diaphragm 5, and is configured to emit an incident electron beam in the form of a parallel beam into the electrostatic deflector 7 for electron deflection, so as to change the off-axis distance of the electron beam passing through the channel in XY directions, respectively.
The electrostatic deflector 7 comprises a plurality of pairs of deflection plates 11, wherein the deflection plates 11 are made of copper material and all the deflection plates 11 are combined to form a channel for the parallel light beams to pass through. In this embodiment, the electrostatic deflector 7 includes four deflection plates 11, and each two deflection plates 11 are in a state of being opposite to and parallel to each other; the two ends of the channel formed by the combination of the four deflection plates 11 are respectively used as an electron beam entrance port and an electron beam exit port, so that the parallel light beams emitted by the magnetic lens 6 enter the channel from the electron beam entrance port and then are transmitted into the imaging unit from the electron beam exit port.
And each deflection plate 11 is connected with a driving circuit for driving the deflection plate 11, and each driving circuit comprises a voltage-adjustable power supply, wherein the voltage adjustment range of the voltage-adjustable power supply is-90V, namely, the voltage-adjustable power supply can output direct current with variable voltage of-90V.
Each of the voltage-adjustable power supplies is provided with N voltage states, and any one of the deflection plates 11 is switched under a combination of N voltages, so that the whole electrostatic deflector 7 has 4 N The different deflection plates 11 are switched.
In this embodiment, as shown in fig. 3, the driving circuit of the electrostatic deflector 7 is provided with four voltage states for each voltage-adjustable power supply, and each output state allows any one of the four voltage values that can be output by the dc regulated power supply with variable output voltage to be connected to its output at any time. At any given time, when a set of switches is activated, the other switches must be forced closed to allow the corresponding direct voltage to be applied to the deflector.
By adjusting the switching times of the four voltages, overshoot that occurs when switching the output state can be substantially eliminated. In addition, since any one of the four deflection plates 11 can be switched under a combination of four voltages, the deflection state of the whole system can be changed from 4 4 Selection of 256 different deflection plate 11 switch states allows precise control of the deflection and scan path of the electron beam.
The voltage combinations of the deflection plates 11 are represented by the following matrix:
this matrix will be applied to the A, B, C, D four deflection plates 11 in fig. 3 to ensure that the electron beams will be deflected to each designated area of the phosphor screen 8 in turn. The electrostatic deflection system may change the electromagnetic field state multiple times at a single time node enabling it to allocate time in a 4 x 4 subframe; that is, the deflection plates 11 can output 4×4=16 images per unit time under the control of the respective driving circuits, and the time resolution is 16 times as high as the original.
The electrostatic deflectors 7 are also connected with signal generators, and the signal generators drive each electrostatic deflector 7 according to self-defined time sequence parameters; wherein the timing parameters include a switching pattern of the electrostatic deflector 7, an exposure time, and a trigger delay time.
In this embodiment, the signal generator is an 8-bit serial digital mode generator, which is operated by custom control software written in LabVIEW and UART communication protocols, and the software allows the user to select the switching mode of the electrostatic deflector 7 and other timing parameters such as exposure time, trigger delay, etc.
The signal generator is triggered by the camera in the imaging unit, synchronizing the exposure of the camera with the deflection of the electrostatic deflector 7. As shown in fig. 2, the scanning of each of the deflection plates 11 starts from the upper left corner, and the upper left corner in fig. 2 is the electron beam starting deflection position 10, and the lower left corner is the electron beam ending deflection position 12; in the case of initialization, it is ensured that the electron beam is scanned from the electron beam starting deflection position 10 and in sequence to the final position of the lower left corner. And the signal generator, in order to perform the control scan cycle in this order, needs each element in the matrix to be given in the following order:
and the imaging unit is arranged right below the electrostatic deflector 7, and comprises a fluorescent screen 8 and a shooting device, wherein the fluorescent screen 8 is opposite to the channel, and ensures that the electron beams are deflected to each appointed area of the fluorescent screen 8 in sequence; the shooting device is arranged below the fluorescent screen 8 and is used for shooting the electron beam spots on the fluorescent screen 8 so as to observe the positions of the electron beam spots emitted through the channels; wherein the camera means is a camera 9.
Example two
The present embodiment provides a transmission electron microscope including the rapid imaging system as described in the first embodiment, and components such as an objective lens, a signal collecting device, and the like included in the electron microscope are disclosed in the prior art and will not be described in detail herein.
The electron microscope in this embodiment and the imaging system described in the foregoing embodiments are based on another aspect of the same inventive concept, and the structure and implementation process of the imaging system have been described in detail in the foregoing, so those skilled in the art can clearly understand the structure and implementation process of the microscope in this embodiment according to the foregoing description, and for brevity of description, the description will not be repeated here.
The above embodiments are only preferred embodiments of the present utility model, and the scope of the present utility model is not limited thereto, but any insubstantial changes and substitutions made by those skilled in the art on the basis of the present utility model are intended to be within the scope of the present utility model as claimed.
Claims (10)
1. The rapid imaging system is characterized by being applied to a transmission electron microscope and comprising an emission unit, a magnetic lens, an electrostatic deflector and an imaging unit which are sequentially and coaxially arranged along the Z-axis direction; the emission unit is used for emitting electrons; the magnetic lens is used for emitting an incident electron beam in the form of a parallel beam;
the electrostatic deflector comprises a plurality of pairs of mutually parallel deflection plates, all the deflection plates are combined to form a channel for a parallel light beam to pass through, and each deflection plate is connected with a driving circuit which is used for driving the deflection plate independently and is used for changing the off-axis distance of the electron beam passing through the channel in the XY direction;
the imaging unit is opposite to the channel and is used for observing the position of the electron beam spot emitted by the channel.
2. The rapid imaging system of claim 1, wherein the emission unit comprises an electron gun, a wegener cap, an anode, a converging mirror, and a converging mirror diaphragm coaxially distributed in sequence; the electron gun is used as an electron source for imaging; the Welch cap is used for focusing electrons; the anode is used for providing acceleration voltage to accelerate the electron beam through the optical axis; the converging mirror is used for focusing the electron beam to the focal position of the magnetic lens; the converging mirror diaphragm is used for limiting the electron dose emitted by the electron gun.
3. The rapid imaging system of claim 1, wherein the electrostatic deflector comprises two pairs of the deflection plates parallel to each other, and the drive circuit to which each of the deflection plates is connected comprises a voltage-adjustable power supply.
4. A rapid imaging system according to claim 3, wherein each of said voltage-adjustable power supplies is provided with N voltage states, any of said deflection plates being switched under a combination of N voltages, such that the overall electrostatic deflector has 4 N Different deflector plate switch states.
5. A rapid imaging system according to claim 3, wherein the deflection plate is a copper plate.
6. The rapid imaging system of claim 3, wherein the electrostatic deflector is further coupled to a signal generator that drives the electrostatic deflector according to a customized timing parameter.
7. The rapid imaging system of claim 6, wherein the timing parameters include a switching mode of the electrostatic deflector, an exposure time, and a trigger delay time.
8. The rapid imaging system of claim 6, wherein the imaging unit comprises a phosphor screen facing the channel and ensuring that the electron beam will deflect sequentially to each designated area of the phosphor screen; the shooting device is arranged below the fluorescent screen and used for shooting the electron beam spots on the fluorescent screen.
9. The rapid imaging system of claim 8, wherein the signal generator is triggered by the camera to synchronize exposure of the camera with deflection of the electrostatic deflector.
10. A transmission electron microscope comprising a rapid imaging system according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222715104.3U CN219085927U (en) | 2022-10-09 | 2022-10-09 | Rapid imaging system and transmission electron microscope |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222715104.3U CN219085927U (en) | 2022-10-09 | 2022-10-09 | Rapid imaging system and transmission electron microscope |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219085927U true CN219085927U (en) | 2023-05-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202222715104.3U Active CN219085927U (en) | 2022-10-09 | 2022-10-09 | Rapid imaging system and transmission electron microscope |
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| CN (1) | CN219085927U (en) |
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- 2022-10-09 CN CN202222715104.3U patent/CN219085927U/en active Active
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