JP4980628B2 - Hysteresis elimination method using automatic transition buttons - Google Patents

Description

  The present invention relates to a method of automatically performing mode transition of a low irradiation function using an automatic transition button when observing a sample using a transmission electron microscope, and removing hysteresis that causes visual field shift.

In observation with a transmission electron microscope (TEM), damage to the sample due to electron beam irradiation is a problem. Especially in biological research, sample damage due to electron beams is a very serious problem. For example, when conducting research using a method called single particle analysis that observes protein molecules or viruses without crystallization, the electron beam exposure allowed for the part to be photographed on the sample is 10 electron / nm before the start of photographing. ² or less. This is because, if an electron beam exceeding this amount is irradiated, particles in the portion on the sample are damaged before photographing.

  For this reason, conventionally, low-illumination photography has been performed. Low-illumination photography consists of the following modes. Lens / deflector conditions for finding the location to be photographed (hereinafter referred to as the search mode), and the lens to be used to remove the defocus and astigmatism avoiding the location when the location to be photographed is found After the operator has set the deflector conditions (hereinafter referred to as the focus mode) and the lens / deflector conditions (hereinafter referred to as the photo mode) when taking a photograph separately and started the operation. Search the field of view in search mode, and when a spot to be photographed is found, switch to photo mode by pressing one button, and after correcting defocus and astigmatism, press another button to switch to photo mode. This is a processing procedure in which a photograph is taken after switching.

  FIG. 7 is a flowchart showing a processing procedure (flow) of a conventional low irradiation function for performing photographing under the above-described restrictions. In FIG. 7, when low-illumination shooting is started, the mode is switched to the search mode in step S21. In step S22, the operator finds a field of view to be photographed. In step S23, when the operator presses the focus mode button, the focus mode is switched in step S24. In step S25, the operator corrects the defocus and the like. Further, when the operator presses the photo mode button in step S26, the mode is switched to the photo mode in step S27. In step S28, a photograph is taken.

  The above steps S21 to S28 are repeated to perform low-illumination shooting.

  In general, in the search mode, a lens value for observing at a low magnification while irradiating a wide range with an electron beam as weak as possible is used to search a field of view. In the focus mode, a lens value that irradiates a narrow range as much as possible after the electron beam is shifted from the optical axis by using a deflector so as not to irradiate the position to be photographed in the photo mode is used. In this way, only a minimum amount of electron beam is irradiated to the photographing location until the mode is changed to the photo mode.

  Such a low-illumination function is incorporated into the transmission electron microscope main body, provided as software on a computer connected to the transmission electron microscope, or automatically determines the shooting location and adjusts focus and astigmatism. It has been provided in variations such as combining with an algorithm that automatically corrects. In addition, the focus mode is divided into a plurality of lens / deflector conditions to correct defocus and astigmatism, and to correct a slight shift in the field of view (hereinafter referred to as tracking mode). Other conditions may be added.

  In either case, however, a shift due to hysteresis occurs when the lens value is switched. FIG. 8 is a diagram for explaining a shift due to hysteresis. For example, as shown in FIG. 8, when a voltage of Vs is applied to a lens in search mode, Vf in focus mode, and Vp in photo mode, the lens to which Vs voltage is applied in the first search mode is Bs1. Even if a magnetic field having a magnitude is generated, if the voltage value is switched between Vf and Vp and then returned to the search mode to Vs, the magnitude Bs2 of the magnetic field generated by the lens is different from the previous value Bs1.

  When this deviation due to hysteresis occurs in the lens that irradiates the sample with an electron beam, the irradiation area is different from the previous one even when returning to the same mode as the previous one when completing one mode transition and moving to the next shooting. Observed as a phenomenon.

  Further, if a shift due to hysteresis occurs in the lens value that expands the electron beam after passing through the sample, the image position is different from the previous one even if the mode returns to the same mode as the previous one.

  This shift results in a difference between the location where you want to shoot and the location where you actually shoot, so the actual operation requires a procedure to remove hysteresis before moving to the search mode, focus mode, and photo mode loops. It becomes.

  FIG. 9 is a processing procedure for explaining a procedure of removing hysteresis. In step S31 to step S33, the hysteresis is removed in order from the search mode, the focus mode, and the photo mode, each time the irradiation area and image shift are corrected by the deflector, and repeated until the shift disappears, and finally twice. Generally, a method of confirming again that there is no shift by looping as much as possible is taken.

  In FIG. 9, in step S31, the lens / deflector conditions for each mode are set. In step S32, hysteresis between modes is removed. In step S33, low-illumination shooting is performed.

  However, since this operation is performed manually, the order of mode transition may be wrong in the middle of repetition. In such a case, hysteresis occurs again, and it is necessary to start the removal operation from the beginning.

  A similar problem occurs during filming. In other words, when you are in search mode, you may accidentally press the photo mode button to switch to focus mode, in which case the hysteresis is restored and the photo is taken without adjusting defocus etc. There is also the negative effect of end.

Patent Document 1 below discloses an electron microscope that enables good sample imaging without generating a deflection field due to hysteresis even when the field of view is searched (search mode) to focus (focus mode). ing. In this conventional electron microscope, the beam is not expanded when searching for a field of view, but a transmission electron image is obtained by scanning an electron beam, and the excitation state of the focusing lens does not change from field of view searching to shooting. For this reason, even when shifting from the visual field search to the focus adjustment, a deflection field due to hysteresis that has been generated conventionally does not occur.
JP 2002-150987 A

  Conventionally, when a transmission electron microscope is used in the search mode to adopt a configuration in which a beam is expanded, the problem of hysteresis has not been solved as described above.

  The present invention has been made in view of the above circumstances, and in adopting a configuration in which a beam is expanded in a search mode in a transmission electron microscope, the imaging location determined by the field of view search cannot be correctly reproduced due to the influence of hysteresis. In order to solve the problem, it is an object of the present invention to provide a hysteresis removal method that can be performed using an automatic transition button without manually performing an operation of removing a hysteresis by executing a mode loop in advance.

  In order to solve the above-described problem, the hysteresis removal method using the automatic transition button according to the present invention has a low irradiation function search mode, focus mode, and photo mode when observing a sample using a transmission electron microscope. This is a hysteresis removal method using an automatic transition button that automatically performs mode transition between them using an automatic transition button and removes hysteresis that causes field of view deviation, and reads the current mode from the transmission electron microscope. A mode reading step; a step of displaying an automatic transition button to be operated by an operator after the mode reading step; and a search of a current mode of the transmission electron microscope when the automatic transition button is operated by the operator. A transition to the next mode in the order of repeating the mode, focus mode, and photo mode, If the deviation due to hysteresis is corrected in the mode in which the transmission electron microscope has changed in response to the transition step, and there is no deviation, the transmission electron microscope repeats the mode transition in the order, and the repetition is performed. And transitioning the mode of the transmission electron microscope to the search mode in the order after the step.

  In this hysteresis elimination method, it is preferable that after the step of repeating the transition, there is a step of allowing an operator to determine whether or not there is a shift due to hysteresis, and if there is no shift, the process proceeds to the step of entering the search mode.

  In addition, after the step of repeating the transition, there is a step of allowing the operator to determine whether or not there is a shift due to hysteresis, and if there is a shift, the automatic transition button is used after the operator has corrected the shift due to hysteresis. It is preferable to shift to the display step.

  According to the present invention, the operator does not cause hysteresis due to mode transitions or fail in shooting, both in shooting with the low illumination function and in hysteresis removal work for that purpose. Also, when repeating mode transition several times for the final confirmation of the hysteresis removal work, it is free from the troublesome repeated work.

  Hereinafter, the best mode for carrying out the present invention will be described. This embodiment is a transmission electron microscope system that executes the hysteresis removal method using the automatic transition button of the present invention to remove hysteresis that causes visual field shift.

  FIG. 1 is a configuration diagram of a transmission electron microscope system. In FIG. 1, the transmission electron microscope 1 incorporates a low irradiation function. In the computer 3, software based on the hysteresis removal method using the automatic transition button of the present invention operates.

  When observing a sample using a transmission electron microscope, this software automatically performs mode transitions between the search mode, focus mode, and photo mode of the low-illumination function using the automatic transition button, thereby reducing the field of view. A program corresponding to a hysteresis removal method using an automatic transition button for removing a causative hysteresis, and a mode reading step for reading the current mode from the transmission electron microscope 1, and an operation performed by the operator after the mode reading step A step of displaying an automatic transition button, a step of transitioning the current mode of the transmission electron microscope 1 to the next mode when the operator operates the automatic transition button, and transmission electron in response to the transition step If the deviation due to hysteresis is corrected in the mode in which the microscope 1 is changed and there is no deviation, the transmission electron Comprising a step of repeating the mode transition to the microscope 1, and the step of the mode of the transmission electron microscope 1 after the step of causing repeated search mode. The software processing procedure will be described later.

  Further, after the step of repeating the transition, there is a step of allowing the operator to determine whether or not there is a shift due to hysteresis, and if there is no shift, the process proceeds to the step of setting to the search mode. In addition, after the step of repeating the transition, in the step of allowing the operator to determine whether or not there is a shift due to hysteresis, if there is a shift, the operator is corrected for the shift due to hysteresis and then the step of displaying the automatic transition button. Transition.

  The transmission electron microscope 1 and the computer 3 are connected by a communication cable 2. A specific example of the automatic transition button is a button written as “transition to the next mode” described later. This button may be provided on the operation panel of the transmission electron microscope 1 or may be provided on the computer 3. As in the prior art, each dedicated button for selecting “search mode”, “focus mode”, and “photo mode” is not provided.

  By executing the software, the computer 3 obtains the current lens, deflector, and sample stage state from the transmission electron microscope 1 and grasps the current mode to make a user interface for transitioning to the next mode. indicate.

  FIG. 2 is a diagram illustrating a specific example of the internal configuration of the transmission electron microscope 1. Inside the lens barrel 11 supported by the gantry 1, an electron gun 13, a first focusing lens 14, a second focusing lens 15, an astigmatism correction coil 16, a deflection coil 17, an objective lens 18, and an intermediate lens 19 are sequentially arranged from the top. The electron optical system components of the projection lens 20 are disposed, and a sample 21 is disposed between the upper magnetic pole piece and the lower magnetic pole piece of the objective lens 18.

  A fluorescent plate 22 is disposed in the image observation chamber 23, and the fluorescent plate 22 is located at the rear stage of the projection lens 20. The fluorescent plate 22 is configured to be disposed (closed) on the optical axis O and retracted (opened) from the optical axis O.

  A photographing device 24 equipped with a photographing film or the like is disposed in a photographing room 25 located at the rear stage of the image observation room 23.

  Next, the processing procedure of the software in the transmission electron microscope system will be described. FIG. 3 is a flowchart showing the processing procedure.

  The operation is started, and in step S1, the operator sets the lens / deflector conditions for each mode. Specifically, the operator uses the low irradiation function incorporated in the transmission electron microscope 1 to set conditions for each lens and deflector in the search mode, the focus mode, and the photo mode.

  In step S2, the computer 3 starts the software of the present invention. Specifically, the operator activates the software of the present invention on the computer 3 with the transmission electron microscope 1 in the search mode, the focus mode, or the photo mode.

  In step S3, the software reads the current mode. Specifically, the software reads the current mode from the transmission electron microscope 1, reads a button that says "Transition to next mode", a button that says "Start confirmation", and a button that says "End" Is displayed.

  In step S <b> 4, the operator presses a “transition to next mode” button displayed on the computer 3. If the current mode is the search mode, the computer 3 sends a command to the transmission electron microscope to switch to the focus mode. However, if the current mode is the focus mode, the command is transmitted, and if the current mode is the photo mode, the command is transmitted so as to transit to the search mode. Thus, in the software, since the computer 3 automatically determines the next mode, there is no possibility that the software will accidentally shift to another mode.

  Next, in step S5, it is determined whether or not there is a deviation. This is done by the operator. The operator visually checks whether there is any deviation in the irradiation area or image position due to hysteresis. If there is no deviation, the process proceeds to step S7 described later.

  If it is determined in step S5 that there is a deviation, the process proceeds to step S6. In step S6, the shift due to hysteresis is corrected. This is also done by the operator. The operator operates the deflector so as to correct the deviation, and returns to step S4.

  In step S7, confirmation work is started. Specifically, the operator presses a “confirmation work start” button displayed on the computer.

  In step S8, the software repeats the transition. The software repeats the operation of transmitting a command to the transmission electron microscope 1 so as to shift to the next mode after the current mode, and makes several transitions in the order of the search mode, the focus mode, and the photo mode. It is assumed that the number of circulations is set in advance by the operator. In this way, in the system, software automatically performs several mode transitions, so that the operator is released from troublesome mode transition operations, and the modes always transition in the correct order.

  Next, in step S9, it is determined whether or not there is no deviation by the operator. Here, the operator visually confirms that there is no shift in the irradiation area or image due to hysteresis. If there is no deviation, the process proceeds to step S11. If there is a deviation, the process proceeds to step S10.

  In step S10, the operator corrects the deviation due to hysteresis. Specifically, the operator operates the deflector so as to correct the deviation, and returns to step S4.

  In step S11, the software sets the search mode. When the operator presses the “END” button displayed on the computer, the software changes the mode in the correct order for the subsequent low-illumination shooting and enters the search mode, and then ends. In other words, if the current mode is the search mode, the software ends as it is. If the current mode is the focus mode, the software transmits a command to the transmission electron microscope to switch to the photo mode once, and then transmits a command to switch to the search mode and then ends. If the current mode is the photo mode, the software terminates after sending a command to switch to the search mode.

  In step S12, low-illumination shooting is started. Specifically, the operator performs low-illumination shooting as shown in FIG.

  As described above, the transmission electron microscope system shown in FIG. 1 fixes the execution order of the search mode, the focus mode, and the photo mode of the low irradiation function by the hysteresis removal method using the automatic transition button of the present invention, The computer controls each mode to be executed in a fixed order from any mode stage. In this way, since the electron lens and the deflector always follow the same history, the field of view can be searched and photographed in the low irradiation mode without being affected by hysteresis. Therefore, in the transmission electron microscope, when taking an electron beam image by the low irradiation function of the electron beam, the field of view is not shifted even when the electron optical system condition for searching the field of view is switched to the condition for shooting. Improve operability.

  In the following, other configuration examples to which the present invention can be applied will be described. Although the above embodiment has been described only in the case of performing low-illumination imaging in the processing procedure of FIG. 7, as described in the background art, there are other variations in the low-illumination imaging sequence. In any case, the present invention can be applied by using software having an interface capable of transitioning only to the next mode.

  In the above embodiment, the transmission electron microscope incorporates a low irradiation function, and the present invention is provided as software that operates on a computer. However, the low irradiation function can also be realized by software. Even in this case, the present invention can be implemented by the software of the present invention communicating with software having a low illumination function, and both the low illumination function and the present invention can be incorporated into a transmission electron microscope. .

  FIG. 4 is a configuration diagram in which the present invention is realized using a low-irradiation function incorporated in a transmission electron microscope (TEM) as software on a computer for the procedure of the hysteresis removal method according to the present invention. For example, the hysteresis removal method software can be stored in a storage device of a computer and executed as necessary. Further, in the transmission electron microscope, software related to the low irradiation function can be provided as firmware.

  FIG. 5 shows that the low-illumination function is realized as software on a computer using an external control interface of a transmission electron microscope (TEM), and can be used together with software that realizes the procedure of the hysteresis removal method according to the present invention. FIG. FIG. 6 (TEM) is a configuration diagram in which the low irradiation function software is incorporated into a transmission electron microscope and used together with the software for realizing the procedure of the hysteresis removal method according to the present invention.

  Furthermore, in the above example, the present invention is used to remove the hysteresis before starting shooting with the low-illumination function, but even during repeated operations of low-illumination imaging as shown in the processing procedure of FIG. By using the interface for “moving to the next mode” provided by the present invention without explicitly specifying the mode transition by the operator, the mistake that the focus mode is skipped and the mode is erroneously shifted to the photo mode. Can be prevented.

It is a block diagram of a transmission electron microscope system. It is a figure which shows the specific example of the internal structure of a transmission electron microscope. It is a flowchart which shows the process sequence based on the hysteresis removal method using the automatic transition button of this invention. It is a block diagram of the present invention. It is a block diagram which shows the other example of application of this invention. It is a block diagram which shows the other example of application of this invention. It is a flowchart which shows the process sequence of the conventional low irradiation function. It is a figure for demonstrating the shift | offset | difference by hysteresis. It is a process procedure for demonstrating the procedure of removing a hysteresis.

Explanation of symbols

1 Transmission Electron Microscope 2 Communication Cable 3 Computer

Claims (3)

When observing a sample using a transmission electron microscope, the mode transition between the search mode, focus mode, and photo mode of the low-illumination function is automatically performed using the automatic transition button, causing hysteresis that causes field-of-view shift. Hysteresis removal method using an automatic transition button to remove
A mode reading step of reading the current mode from the transmission electron microscope;
After the mode reading step, displaying an automatic transition button to be operated by the operator;
When the automatic transition button is operated by an operator, the current mode of the transmission electron microscope is changed to the next mode in the order of repeating the search mode, the focus mode, and the photo mode,
If the shift due to hysteresis is corrected in the mode in which the transmission electron microscope has transitioned in response to the transition step and there is no shift, the transmission electron microscope repeats the mode transition in the order;
And a step of transitioning the mode of the transmission electron microscope to the search mode in the order after the repeating step. A method for removing hysteresis using an automatic transition button.   2. The method according to claim 1, further comprising the step of allowing an operator to determine whether or not there is a shift due to hysteresis after the step of repeating the transition, and if there is no shift, the process proceeds to the step of entering the search mode. Hysteresis removal method using automatic transition buttons.   After the step of repeating the transition, there is a step of allowing an operator to determine whether or not there is a shift due to hysteresis, and if there is a shift, display the automatic transition button after correcting the shift due to hysteresis by the operator. 2. The method for removing hysteresis using an automatic transition button according to claim 1, wherein the step moves to a step.

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