Annular dark field detector based on pneumatic control of scintillator probe displacement and application thereof

Abstract

The invention discloses an annular dark field detector based on pneumatic control of scintillator probe displacement and application thereof. The detector comprises a scintillator probe on the innermost layer and a photomultiplier tube, the scintillator probe is limited in the upper portion of an inner sleeve with a corrugated tube through an outer expansion body at the bottom of the scintillator probe, the scintillator probe and the inner sleeve are connected through threads, and the photomultiplier tube is arranged in the lower portion of the inner sleeve. The scintillator probe is coupled with the scintillator probe through a metal threaded ring of the scintillator probe external expansion body and a clamping sleeve on the lower portion of the inner sleeve, the upper portion of the inner sleeve and part of the lower portion of the inner sleeve are wrapped in the middle sleeve, the outer sleeve and the base are located on the outermost layer, and the outer sleeve, the upper portion of the inner sleeve and the external expansion portion of a straight notch of the middle sleeve make close contact. The base is located at the tail end of the ferrule. Based on a pneumatic structure of the detector, the detector is used in a scanning transmission electron microscope, so that the displacement process is stable and noiseless, the drying of a test result caused by an electromagnetic signal can be fundamentally avoided, and the test accuracy of the electron microscope is effectively improved.

Description

TECHNICAL FIELD

[0001] The application relates to a ring-shaped dark field detector, in particular to a ring-shaped dark field detector based on pneumatic control of displacement of a scintillator probe and application thereof, and belongs to the technical field of material detection. BACKGROUND

[0002] Different detectors are equipped in a scanning transmission electron microscope to collect various signals, enhance imaging contrast, provide complementary information, adapt to different experimental requirements and improve experimental flexibility, so that more comprehensive and accurate sample information can be obtained. However, some detectors are not needed to collect data in some imaging modes, for example, when a transmission electron microscope mode is used in a scanning transmission electron microscope, data is not needed to be collected by a ring-shaped dark field detector, at this time, if the ring-shaped dark field detector is still in the working position, other detectors will be blocked to receive electronic information, and the imaging quality will be affected. In order to facilitate the scanning transmission electron microscope to freely switch the imaging mode, the simplest method is to design the detector to control the working position of the detector probe through stretching and retracting, so as to meet the needs of the imaging mode of the scanning transmission electron microscope.

[0003] The stretching and retracting control of the traditional ring-shaped dark field detector is to control the stretching and retracting position of the scintillator probe of the ring-shaped dark field detector by a motor. However, the electric control scheme adopted in the prior art has the following problems:

[0004] 1) Since the motor for controlling the stretching and retracting of the detector is very close to the photomultiplier tube and nuclear electronics device, when the detector is stretched and retracted, the instantaneous high-frequency noise current generated by the motor will interfere with the ring-shaped dark field detector, mask the weak signal, cause the measured signal to be distorted, reduce the signal-to-noise ratio (SNR), and affect the measurement accuracy. Through additional shielding or additional filtering measures, the interference influence can be reduced and the conducted interference can be suppressed, which undoubtedly increases the complexity of the entire system and improves the equipment maintenance cost.

[0005] 2) The mechanical vibration (such as harmonic vibration in micro-step) caused by starting and stopping or speed changing of the motor, the frequency and duty cycle of the PWM control signal may excite mechanical resonance, and the noise caused by such high-frequency vibration may be transmitted to sensitive components such as cables and amplifiers through the structure, thereby being superimposed on the measured signal to cause signal misjudgment. By introducing additional vibration isolation design (such as flexible coupling, damping material), such problems can be effectively suppressed, but the cost of the entire system is increased.

[0006] 3) The inside of the scanning transmission electron microscope cavity is a strong magnetic field environment, which is the main working scene of the annular dark field detector. The cables (such as power lines and signal lines) in the motor control system may become a radiation source or a receiving source of electromagnetic noise, so the motor control system may cause control signal distortion or equipment failure due to EMI in a strong magnetic field environment. Additional electromagnetic shielding devices can reduce the interference of the magnetic field on the motor, but they cannot completely avoid the risk of equipment failure in a strong magnetic field environment.

[0007] Therefore, the prior art urgently needs an annular dark field detector without electromagnetic interference and precise control. SUMMARY

[0008] In view of the problems existing in the prior art, the first object of the present application is to provide an annular dark field detector based on pneumatic control of scintillator probe displacement. The detector uses pneumatic control, and through the gas guide structure and limiting device between the components, it achieves the technical purpose of precise and rapid extension and contraction of the annular dark field detector. The detector does not use any electronic equipment, so it not only can achieve smooth and noise-free operation, but also can fundamentally avoid the interference of electromagnetic signals on the test results, effectively improving the accuracy of electron microscope testing.

[0009] The second object of the present application is to provide an application of an annular dark field detector based on pneumatic control of scintillator probe displacement, which is used in a scanning transmission electron microscope. Based on the advantages of the above-mentioned annular dark field detector, the electron microscope device does not need to be additionally provided with shielding, filtering, vibration isolation and damping devices, which greatly reduces the complexity of the system. Not only does it effectively reduce the initial cost, operating cost and maintenance cost of the system, but it also effectively avoids the influence of system errors on the test results. The pneumatic device with a pure mechanical structure has better stability and lower failure rate, which can meet the requirements of long-term stable operation of the scanning transmission electron microscope.

[0010] In order to achieve the above technical purposes, the present application provides an annular dark field detector based on pneumatic control of scintillator probe displacement, which comprises: a scintillator probe and a photomultiplier tube located in the innermost layer. The scintillator probe is limited in the upper part of the inner sleeve with a bellows through its bottom expansion body. The upper part of the inner sleeve is connected with the lower part of the inner sleeve through a thread. The photomultiplier tube is built-in in the lower part of the inner sleeve, which is tightly coupled with the scintillator probe through the metal thread ring of the scintillator probe expansion body and the sleeve of the lower part of the inner sleeve. The upper part of the inner sleeve and part of the lower part of the inner sleeve are wrapped in the middle sleeve. The outer sleeve and the base are located in the outermost layer. The straight slot of the outer sleeve, the upper part of the inner sleeve and the middle sleeve is tightly contacted. The base is located at the tail end of the sleeve and is combined with the outer sleeve through a thread.

[0011] The nuclear electronic signal is very small and easy to be disturbed, and the motor-driven control of the expansion and contraction of the scintillator probe in the prior art causes great disturbance to the measurement, thereby affecting the measurement accuracy. The pneumatic method used in the application uses a simple mechanical pneumatic structure and a limiting structure, fully utilizes the air pressure difference between the inside of the scanning transmission electron microscope and the inside of the annular dark field detector to achieve the purpose of controlling the expansion and contraction of the scintillator probe, avoids the use of a large-current motor drive, and thus improves the integrity and accuracy of the measurement signal.

[0012] As a preferred scheme, the straight slot of the upper part of the inner sleeve is further provided with an air inlet on the outwardly expanded part, for air charging and air extraction.

[0013] As a preferred scheme, the inner side of the metal threaded ring of the scintillator probe is further provided with a rubber ring for maintaining air tightness. The rubber ring can protect the outwardly expanded part of the scintillator probe on one hand, reduce the vibration and impact of the equipment during work, and prevent the scintillator probe from being damaged during work, and on the other hand, fill the micro gaps through elastic deformation to block the gas leakage path, so that an air pressure difference is generated between the inside of the annular dark field detector and the inside of the scanning transmission electron microscope cavity, and the purpose of pneumatic control is achieved.

[0014] As a preferred scheme, the diameter of the outwardly expanded body of the scintillator probe is greater than the diameter of the photomultiplier tube, so as to ensure that the fluorescent photons emitted from the scintillator are completely absorbed by the photomultiplier tube.

[0015] The outwardly expanded diameter of the bottom of the scintillator probe is slightly greater than the diameter of the photomultiplier tube, so as to ensure that almost all the fluorescent photons emitted from the scintillator are collected by the photomultiplier tube, and the signal-to-noise ratio is improved; the internal diameter of the upper part of the inner sleeve with the bellows is greater than the cylindrical diameter of the scintillator probe, but less than the outwardly expanded diameter of the bottom of the scintillator probe, the bottom of the scintillator probe is limited in the bottom inner groove of the upper part of the inner sleeve with the bellows, and the cylindrical part of the scintillator probe is located inside the bellows. When the bellows is in the contracted state, the scintillator probe extends outwardly to the annular dark field detector; when the bellows is in the expanded state, the scintillator probe is retracted to the inside of the annular dark field detector.

[0016] As a preferred scheme, the lower part of the inner sleeve is in a circular table structure, the diameter of the circular table top is less than the inner diameter of the middle sleeve, and the diameter of the circular table bottom is greater than the inner diameter of the middle sleeve.

[0017] The inner sleeve upper part with bellows is in the inner layer and is connected with the inner sleeve lower part through threads; the middle sleeve is in the middle layer, the outer diameter of the cylindrical part of the middle sleeve is equal to the outer diameter of the bottom expansion part of the inner sleeve lower part, which limits the inner sleeve lower part; when the bellows is contracted, the inner sleeve lower part moves to the scintillator probe due to the connection with the inner sleeve upper part through threads; when the inner sleeve lower part moves to the bottom expansion part being stopped by the middle sleeve, the bellows cannot continue to move, and the bellows reaches the maximum contraction state.

[0018] The outer sleeve and the base are in the outermost layer and are connected through threads, the inner sleeve upper part with bellows, the middle sleeve and the straight slot expansion part of the outer sleeve are in close contact; the size of the straight slot of the outer sleeve is the largest, the size of the straight slot of the inner sleeve upper part is equal to the size of the straight slot of the outer sleeve, and the size of the straight slot of the middle sleeve is slightly smaller; when the bellows is elongated, the inner sleeve lower part extends to the base; when the bottom of the inner sleeve lower part is stopped by the inner groove of the base, the bellows cannot continue to elongate, and reaches the maximum elongation state; the length of the outer sleeve is the maximum elongation length of the bellows.

[0019] As a preferred scheme, the middle sleeve is further provided with a mechanical device with a pressure sensor, which is coupled through the positioning column and the positioning hole on the outer sleeve.

[0020] As a preferred scheme, the mechanical device contains a small three-legged micro switch inside, and when the inner sleeve lower part contacts the spring of the micro switch, a signal is sent out.

[0021] The application further provides an application of the annular dark field detector based on the pneumatic control of the displacement of the scintillator probe, which is used for a scanning transmission electron microscope, and the assembly process is as follows: the scintillator probe of the detector is inserted into the inside of the cavity of the scanning transmission electron microscope, the remaining device parts are outside the cavity, and the straight slot surface of the inner sleeve upper part with bellows is tightly attached to the outer surface of the cavity of the scanning transmission electron microscope.

[0022] As a preferred scheme, when the scanning transmission electron microscope is in the scanning electron microscope mode, the gas is filled into the gas inlet, and the scintillator probe is exposed.

[0023] As a preferred scheme, when the scanning transmission electron microscope is in the transmission electron microscope mode, the gas is extracted from the gas inlet, and the scintillator probe is retracted.

[0024] As a preferred scheme, the process of the exposure of the scintillator probe is as follows: when the gas is filled into the gas inlet, the scintillator probe moves to the inside of the cavity of the scanning transmission electron microscope, drives the bellows of the inner sleeve upper part to contract, and the inner sleeve lower part moves to the middle sleeve; when the bellows is completely contracted, the scintillator probe is completely exposed.

[0025] As a preferred scheme, the process of the scintillator probe is that when the gas is extracted from the gas inlet, the scintillator probe is retracted into the annular dark field detector, the bellows at the upper part of the inner sleeve with the bellows is in a fully stretched state, at this time, the lower part of the inner sleeve is tightly contacted with the internal protrusion limiting part of the base, and the scintillator probe is fully retracted.

[0026] Compared with the prior art, the technical scheme of the present application has the beneficial technical effects that:

[0027] 1) The annular dark field detector provided by the present application adopts pneumatic control, and through the gas guide structure and the limiting device between the components, the technical purpose of accurate and rapid expansion and contraction of the annular dark field detector is achieved; the detector does not use any electronic equipment, can not only realize stable and noiseless movement, but also can fundamentally avoid the interference of electromagnetic signals on the test results, and effectively improve the accuracy of electron microscope testing.

[0028] 2) The pneumatic system used in the technical scheme provided by the present application has the advantages of simple mechanical structure, small vibration amplitude, low vibration frequency, no electromagnetic noise and no mechanical vibration interference, which can maximize the purity of the electron microscope measurement signal, and the low noise characteristics of the pneumatic system in the start-stop stage and the running stage can also maintain the stability of the electron microscope test environment, avoiding the interference of noise on the measurement signal.

[0029] 3) In the technical scheme provided by the present application, based on the advantages of the above-mentioned annular dark field detector, the electron microscope device does not need to additionally set shielding, filtering, vibration isolation and damping devices, which greatly reduces the complexity of the system, not only effectively reduces the initial cost, operation cost and maintenance cost of the system, but also effectively avoids the influence of system error on the test results, and the pneumatic device with pure mechanical structure has better structural stability and lower failure rate, which can meet the requirements of long-term stable operation of the scanning transmission electron microscope. BRIEF DESCRIPTION OF DRAWINGS

[0030] Fig. 1 It is an external structure schematic view of the annular dark field detector provided by the embodiment 1 of the present application.

[0031] Fig. 2 It is an exploded view of the annular dark field detector provided by the embodiment 1 of the present application.

[0032] Fig. 3 It is a scintillator probe limiting schematic view of the annular dark field detector provided by the embodiment 1 of the present application.

[0033] Fig. 4 It is an internal structure schematic view of the annular dark field detector provided by the embodiment 1 of the present application.

[0034] Fig. 5 It is an intermediate layer structure schematic view of the annular dark field detector provided by the embodiment 1 of the present application.

[0035] Fig. 6 This is a cross-sectional view of the outer layer of the annular dark field detector provided in Example 1 of the present invention;

[0036] Fig. 7 A cross-sectional view of the mechanical assembly of the annular dark field detector with a pressure sensor provided in Example 1 of the present invention;

[0037] Figs. 1-7 In the figure, 1-scintillator probe; 2-air inlet; 3-mechanical assembly with pressure sensor; 4-external sleeve; 5-base; 6-photomultiplier tube; 7-upper part of inner sleeve with bellows; 8-intermediate sleeve; 9-lower part of inner sleeve; 10, rubber ring; 11, metal threaded ring; 12, ferrule at the lower part of inner sleeve. DETAILED DESCRIPTION

[0038] The following will be combined with the attached table of the embodiment of the present invention to clearly and completely describe the technical solutions in the embodiment of the present invention. Obviously, the embodiment described is only a part of the embodiment of the present invention, not all embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] This embodiment provides an annular dark field detector based on pneumatically controlled scintillator probe displacement, such as Figs. 1-3 As shown, it includes a scintillator probe 1 and a photomultiplier tube 6 located in the innermost layer. The scintillator probe is limited in the upper part 7 of the inner sleeve with a bellows through its bottom expansion body. The upper part of the inner sleeve is connected to the lower part 9 of the inner sleeve by threads. The photomultiplier tube is built into the lower part of the inner sleeve and is tightly coupled to the scintillator probe through the metal threaded ring 11 of the scintillator probe expansion body and the clamping sleeve 12 of the lower part of the inner sleeve. The entire upper part of the inner sleeve and part of the lower part of the inner sleeve are wrapped in the middle sleeve 8. The outer sleeve 4 and the base 5 are in the outermost layer, wherein the outer sleeve, the upper part of the inner sleeve and the straight groove expansion part of the middle sleeve are in close contact. The base is located at the tail end of the clamping sleeve and is combined with the outer sleeve by threads.

[0041] An air inlet 2 is provided on the outer expansion portion of the straight slot on the upper portion of the inner sleeve for inflation and degassing; a rubber ring 10 is provided on the inner side of the metal threaded ring of the scintillator probe for maintaining air tightness;

[0042] The diameter of the scintillator probe outer expansion body is larger than the diameter of the photomultiplier tube, ensuring that the fluorescent photons emitted from the scintillator are completely absorbed by the photomultiplier tube;

[0043] The lower part of the inner sleeve is a circular truncated cone structure, the diameter of the truncated cone table is less than the inner diameter of the middle sleeve, and the diameter of the truncated cone bottom is greater than the inner diameter of the middle sleeve;

[0044] The middle sleeve is further provided with a mechanical device 3 with a pressure sensor, which is coupled through a positioning column and a positioning hole on the outer sleeve; the mechanical device contains a small micro switch with three legs, and when the lower part of the inner sleeve contacts the spring of the micro switch, a signal is sent outward.

[0045] The assembly process of the annular dark field detector applied to the scanning transmission electron microscope is as follows: the scintillator probe of the detector is inserted into the cavity of the scanning transmission electron microscope, and the remaining device parts are outside the cavity, and the straight groove surface of the upper part of the inner sleeve with the bellows is tightly attached to the outer surface of the scanning transmission electron microscope cavity.

[0046] The air pressure in the gap between the scintillator probe and the upper part of the inner sleeve with the bellows is equal to the air pressure P1 in the cavity of the scanning transmission electron microscope, and the air pressure in the annular dark field detector is P2, and the air pressure boundary is the bottom of the scintillator probe. The air pressure in the annular dark field detector is adjusted through the gas inlet 2, and a pressure difference is generated between the cavity of the scanning transmission electron microscope, so as to achieve the purpose of controlling the extension of the scintillator probe 1. Specifically, the pneumatic control process of the annular dark field detector is as follows:

[0047] By connecting the external gas device with the gas inlet, the gas is sent into the annular dark field detector, so that the internal air pressure P2 rises, and since P2>P1, the bottom of the scintillator probe as the air pressure difference boundary is affected by the air pressure gradient force, and starts to move to the inside of the scanning transmission electron microscope cavity, while driving the bellows to move, so that it starts to shrink. When the scintillator probe reaches the maximum extension state, the bottom of the inner sleeve is in contact with the bottom of the middle sleeve, and the bellows reaches the maximum shrinkage limit, and the mechanical assembly with the small micro switch with three legs will send a signal to the outside.

[0048] When the external gas device is used to pump out the gas from the annular dark field detector, the bellows starts to extend due to the rebound characteristics, and when the lower part of the inner sleeve is in contact with the inner recess of the base, the bellows almost reaches the maximum extension limit, and the scintillator probe is retracted into the annular dark field detector.

Claims

1. An annular dark field detector based on pneumatically controlled scintillator probe displacement, characterized in that: include: The scintillator probe (1) and the photomultiplier tube (6) are located in the innermost layer. The scintillator probe is limited in the upper part of the inner sleeve (7) with the bellows through the outer expansion body at the bottom thereof. The upper part of the inner sleeve is connected to the lower part of the inner sleeve (9) through a thread. The photomultiplier tube is built into the lower part of the inner sleeve and is tightly coupled with the scintillator probe through the metal threaded ring (11) of the outer expansion body of the scintillator probe and the clamping sleeve (12) at the lower part of the inner sleeve. The entire upper part of the inner sleeve and part of the lower part of the inner sleeve are wrapped in the middle sleeve (8). The outer sleeve (4) and the base (5) are in the outermost layer, wherein the outer sleeve, the upper part of the inner sleeve and the straight groove outer expansion part of the middle sleeve are in close contact. The base is located at the tail end of the clamping sleeve and is combined with the outer sleeve through a thread.

2. The annular dark field detector based on pneumatically controlled scintillator probe displacement according to claim 1, characterized in that: An air inlet (2) is also provided on the outwardly expanded portion of the straight slot on the upper portion of the inner sleeve; and a rubber ring (10) is also provided on the inner side of the metal threaded ring of the scintillator probe.

3. The annular dark field detector based on pneumatically controlled scintillator probe displacement according to claim 1, characterized in that: The diameter of the scintillator probe outer expansion body is larger than the diameter of the photomultiplier tube.

4. The annular dark field detector based on pneumatically controlled scintillator probe displacement according to claim 1, characterized in that: The lower part of the inner sleeve is a frustum structure, the diameter of the frustum surface is smaller than the inner diameter of the middle sleeve, and the diameter of the frustum bottom is larger than the inner diameter of the middle sleeve.

5. The annular dark field detector based on pneumatically controlled scintillator probe displacement according to claim 4, characterized in that: The intermediate sleeve is also provided with a mechanical device (3) with a pressure sensor, which is coupled via a positioning column and a positioning hole on the outer sleeve; the mechanical device contains a three-pin small micro switch inside, and when the lower part of the inner sleeve contacts the spring of the micro switch, a signal is sent out.

6. Application of an annular dark field detector based on pneumatically controlled scintillator probe displacement according to any one of claims 1 to 5, wherein the process is: used in a scanning transmission electron microscope, and the assembly process is: inserting the scintillator probe of the detector into the scanning transmission electron microscope cavity, with the remaining device parts outside the cavity, and the straight groove surface on the upper part of the inner sleeve with the bellows in close contact with the outer surface of the scanning transmission electron microscope cavity.

7. The application of an annular dark field detector based on pneumatically controlled scintillator probe displacement according to claim 6, wherein the process is as follows: when the scanning transmission electron microscope is in scanning electron microscope mode, gas is filled into the air inlet and the scintillator probe is extended; when the scanning transmission electron microscope is in transmission electron microscope mode, gas is extracted from the air inlet and the scintillator probe is retracted.

8. The application of an annular dark field detector based on pneumatically controlled scintillator probe displacement according to claim 7, wherein the process of the scintillator probe extending out is as follows: when gas is filled into the air inlet, the scintillator probe moves toward the interior of the scanning transmission electron microscope cavity, driving the bellows at the upper part of the inner sleeve to contract, and the lower part of the inner sleeve to move toward the middle sleeve; when the bellows is fully contracted, the scintillator probe is fully extended out.

9. The application of an annular dark field detector based on pneumatically controlled displacement of a scintillator probe according to claim 7, wherein the process of extending the scintillator probe is as follows: when gas is extracted from the air inlet, the scintillator probe contracts toward the inside of the annular dark field detector, and the bellows on the upper part of the inner sleeve with the bellows is in a fully extended state. At this time, the lower sleeve of the inner sleeve is in close contact with the internal protrusion limit of the base, and the scintillator probe is completely contracted.

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