Switchable target quasi-monochromatic microfocus x-ray source device and energy control method

Abstract

The present application relates to the technical field of micro-focus X-ray source, and discloses a switchable target quasi-monochromatic micro-focus X-ray source device and an energy control method.The device comprises an electron gun assembly, a multi-target-zone indexing target disc, a micro-focus bunching coil, a quasi-monochromatic filter insert, a energy spectrum sampling probe, a target disc cooling channel, a high-voltage controller and a vacuum sealed shell.After target replacement, effective exposure is first prohibited, the target zone identification and locking state are checked, and the spectrum peak, focus, filter depth and target temperature state are obtained after cooling and vacuum condition establishment;the controller corrects the target position, bunching current, filter depth and tube voltage in sequence, and effective exposure is opened only after all states enter the allowable window.When the state is out of limit, the beam is stopped, the safe target zone is returned and recalibrated.The exposure of each time is saved in correspondence with the target zone identification and calibration version.The scheme is used for multi-material absorption edge imaging and material differentiation.

Description

Technical Field

[0001] This invention belongs to the field of X-ray source and beam control technology, specifically involving an X-ray source device and energy control method that switches different target material regions within the same vacuum chamber, forms micro-focus characteristic spectral lines, and implements beam gating based on the target position, energy spectrum, focus, filtering, and thermal state after target switching. Background Technology

[0002] Microfocus X-ray sources generate X-rays by focusing an accelerated electron beam onto a small target area. The focal spot size affects geometrical unsharpness, while the target material type, tube voltage, and filtering conditions collectively influence the emitted energy spectrum; therefore, spatial resolution and energy selectivity are not independent design parameters.

[0003] When a target is bombarded by an electron beam, it generates both a continuous spectrum and characteristic spectral lines associated with the target element. For absorption edge imaging or material differentiation, it is desirable to match the characteristic spectral lines with the energy-sensitive region of the measured material, while suppressing spectral bands that contribute little to the discrimination, in order to improve the separability of responses from adjacent materials.

[0004] A fixed target can only provide a limited combination of characteristic spectral lines. If the same device needs to target objects with different absorption edges, such as copper and molybdenum, simply changing the tube voltage can only change the endpoints and relative intensities of the continuous spectrum; it cannot transform the characteristic spectral lines of a fixed target into those of another target.

[0005] Setting up target regions of different materials within a single X-ray tube and selecting these regions by rotation or translation is one approach to obtaining a variety of characteristic spectral lines. However, the ability to switch target regions does not equate to immediately obtaining a stable quasi-monochromatic beam suitable for microfocal imaging after target switching.

[0006] First, when the target disc rotates from one target area to another, it undergoes driving, deceleration, and locking. Bearing clearance, locking backlash, differences in target area installation height, and thermal expansion can all cause the actual bearing position to deviate from the calibrated position of that target area. The target disc command angle and the actual mechanical state after locking are not the same quantity. Only by confirming both the target area markings and the locking state can the possibility of the motor stopping before the rotation has stabilized be ruled out.

[0007] Secondly, the slight change in the target surface's position relative to the electron optical axis after target replacement alters the electron beam's landing point and focal point shape on the target surface. Even if the focusing current remains unchanged, it cannot be assumed that the focal point position and size are still the same as before the target replacement. This focal point change simultaneously affects both spatial resolution and target power density; if judged solely based on emission intensity, focal point enlargement and beam current changes may produce similar flux results, making it difficult to determine whether focusing or high voltage correction is necessary.

[0008] Furthermore, the electron beam energy deposition, heat conduction path, and allowable temperature rise may differ for different target materials. If the cooling system operates only at the total power of the entire system without identifying the current target area, the temperature rise on the target surface will change the local morphology of the target area and the stability of the emission spectrum, and may cause the lock-up error to increase with operating time.

[0009] Quasi-monochromatic filtering is typically achieved by setting filter materials and thicknesses that are compatible with the target spectral band in the beam exit path. If the filter is inserted too shallowly, unnecessary spectral bands will not be attenuated sufficiently; if inserted too deeply, the effective flux loss will increase. Furthermore, its optimal operating point will change depending on the target material, tube voltage, and actual peak state. The filtered peaks, spectral width, and flux should be recorded corresponding to the measured insertion depth; otherwise, the filter drive hysteresis will be mistakenly interpreted as a change in the target energy spectrum, leading to incorrect tube voltage corrections.

[0010] Therefore, simply switching a predetermined filter mechanically according to the target area number, or giving a fixed insertion depth based solely on historical parameters, cannot eliminate the influence of target position hysteresis, focus changes, and target surface temperature on the emitted energy spectrum.

[0011] In conventional control methods, the target disk drive, focusing power supply, filter drive, high-voltage power supply, and cooling circuit may each complete a local closed loop. Even if each local closed loop reports "in place," their reports may come from different sampling times or different calibration versions. The sampling delay of different local closed loops can also cause the controller to combine the focal state of the previous target area with the energy spectrum state of the current target area. On the surface, every value is within the range, but the combined state has not actually appeared.

[0012] If the controller immediately opens the formal exposure after the target disk is locked, data with unverified spectral peaks and focus will enter the imaging sequence. Subsequent image processing can change the grayscale or correct some geometric errors, but it cannot restore the true target area, focus, filter depth, and temperature state at that time.

[0013] Measuring only the energy spectrum peak position is insufficient to confirm the microfocal operating point. Even if the peak is located within the target window, the electron beam landing point may still deviate from the predetermined position or the focal size may have increased; conversely, detecting only the focal image cannot confirm that the characteristic spectral lines match the target absorption edge. Therefore, it is necessary to simultaneously obtain the results from both the energy spectrum measurement channel and the focal imaging channel, and use the same target change event identifier to constrain the temporal assignment of both.

[0014] Adjusting the filter insert can also alter the spectral shape and flux received by the sampling probe. If the filter depth and tube voltage are repeatedly changed before the focus is stable, multiple control quantities will affect each other, making it difficult for the controller to determine whether the deviation is caused by the target area, the focusing state, or the filtering state.

[0015] Target replacement control also involves safety boundaries. Applying an electron beam when the target disk is not locked, cooling is not established, or the vacuum condition is unqualified will increase the risk of target surface damage, abnormal discharge, and accidental exposure; if the parameters before the limit is exceeded are continued after the anomaly occurs, the failure state will be carried into the recovery process.

[0016] Existing devices often treat "completion of rotation", "beam current reaching the set value", "filter in place" and "high voltage establishment" as independent permission conditions, lacking joint status verification and effective exposure gating for the same target change event.

[0017] On the other hand, the required tube voltage, beam current, focusing current, filter insertion depth, peak allowable window, focus allowable window, and upper temperature limit are not entirely the same for different target regions. If these parameters are not saved in a group with the target region identifier, historical parameters from another target region may be called when changing targets. The calibration parameter group should also save the allowable window and calibration version, so that the controller can identify whether the parameter comes from a valid version after this maintenance, rather than simply calling it by file name or last modification time.

[0018] When spectral peaks, focal points, or temperatures exceed limits, some systems only modify the last control variable. If the root cause of the limit exceedance is actually an incorrect target selection or incomplete lock-up, this local correction will not only fail to restore the correct state but may also push the tube voltage or filter depth to an inappropriate operating point.

[0019] To obtain verifiable quasi-monochrome microfocus beam output, a calibration beam output process needs to be set up before the formal exposure, and the order of obtaining each state quantity, the calibration object, and the pass / fail criteria need to be clearly defined during the calibration process.

[0020] The calibration process should also correlate the mechanical, electro-optical, energy spectrum, and thermal states under the same target change event, so that the controller can determine whether the current output actually comes from the selected target area and its corresponding calibration parameter set.

[0021] When an anomaly occurs, it is necessary to first prevent the unqualified state from entering the valid data, then return the target disk to the preset safe target area, and re-acquire the focus and energy spectrum after the locking, cooling and vacuum conditions are re-established, instead of directly using the cached results before the anomaly.

[0022] Therefore, the problem that needs to be solved in this field is not simply adding multiple targets, filters, or energy spectrum detectors, but rather how to establish the correspondence between the target area, focus, filter, and energy spectrum in a controlled order after target replacement, and to determine whether effective exposure is allowed based on this correspondence.

[0023] Without adding unverified technical results, this case focuses on solving the state mismatch and correction coupling problems after target replacement, so as to form an feasible cooperative link for multi-target region transposition, micro-focus beam focusing, quasi-monochromatic filtering, energy spectrum detection, cooling and high-voltage beam output.

[0024] Regarding the known structure of multi-target rotation and target replacement, the device closest to this case typically features independent target disk drive closed loops, focusing power supply closed loops, filter drive closed loops, and high-voltage closed loops, using the positioning signals reported by each closed loop as the basis for beam output. In such devices, the target position, focus, energy spectrum, filtering, and thermal state after target replacement are not constrained by the same target replacement event, nor are they subject to a joint gating system that continuously prohibits effective exposure until calibration is successful. To shorten the waiting time after target replacement, such devices tend to directly use the parameter combination from the most recent calibration before target replacement. The aforementioned devices do not provide a solution for ensuring that the beam output conditions after target replacement are verifiable and referential without using old calibrations or introducing unconfirmed states. Summary of the Invention

[0025] The purpose of this invention is to provide a switchable target quasi-monochromatic microfocus X-ray source device and energy control method, so that each target area switch undergoes target area confirmation, focus correction, energy spectrum correction and joint state gating, reducing the possibility of state mismatch after target change leading to effective exposure.

[0026] To achieve the above objectives, the device includes an electron gun assembly, a multi-target rotation target disk, a microfocus focusing coil, a quasi-monochromatic filter insert, an energy spectrum sampling probe, a target disk cooling channel, a high-voltage controller, and a vacuum-sealed housing.

[0027] The vacuum-sealed housing provides the vacuum space required for electron beam generation, transmission, focusing, and bombardment of the target area, and houses the X-ray beam exit window. The electron gun assembly, multi-target rotation disk, and microfocus focusing coil are located within this vacuum space, while the quasi-monochromatic filter insert is positioned on the beam exit path extending outward from the beam exit window.

[0028] The multi-target rotation target disk has at least two target regions made of different materials. Each target region is separated circumferentially or arranged in a planar array, and is brought to the electron beam bombardment position by the same rotation mechanism, thereby changing the target material that produces characteristic spectral lines without disassembling the vacuum shell.

[0029] Each target area has a fixed target area identifier. The target area identifier is used to associate the target type with its tube voltage, beam current, focusing current, filter insertion depth, and allowable state window. It cannot be determined solely by the target angle of the drive motor. The target area identifier can be implemented by a fixed code, a position code, or an identification structure that can correspond one-to-one with the actual target area; the common requirement is that the reading result comes from the actual position after locking.

[0030] The indexing and locking mechanism restricts the target disk from continuing to rotate after the target area reaches the bombardment position. The high-voltage controller simultaneously checks the target area markings and the locking status; if the two do not correspond, the effective exposure prohibition state is maintained.

[0031] The target disk cooling channel forms a thermal connection with the back of each target area. The cooling inlet, cooling circuit, and thermal sensors are arranged with the target disk structure, enabling the controller to obtain the temperature status of the current target area and adjust the cooling conditions according to the tube current and temperature status.

[0032] The electron gun assembly generates and accelerates the electron beam. The tube voltage determines the electron energy range, and the beam current affects the number of electrons that bombard the target surface per unit time; these two, together with the target material type and thermal load, constitute part of the calibration parameter set.

[0033] The micro-focusing coil is positioned between the electron gun assembly and the multi-target rotation target disk. The focal position and size of the electron beam on the target surface are adjusted by changing the excitation current. After target replacement, the focusing current of the previous target area is not directly reused; instead, the initial value of the current target area is called and corrected based on the current focus image.

[0034] The quasi-monochromatic filter insert is driven by a linear mechanism to change its effective insertion depth in the beam exit path, and the insertion depth feedback element returns the measured position to the high-voltage controller. Each target region has a corresponding initial filter insertion depth, which is used to begin energy spectrum correction rather than as a final value for opening exposure without measurement.

[0035] The energy spectrum sampling probe is positioned at a sampling location capable of receiving emitted X-rays. Its energy spectrum measurement channel outputs at least two of the following: peak center, peak width, and flux, to determine whether the emitted beam is within the target characteristic spectral line window.

[0036] The energy spectrum sampling probe also has a focal imaging channel, or forms a single sampling component with the focal imaging channel, outputting a focal image and obtaining the focal position and size accordingly. The energy spectrum quantity and focal quantity are stored using the same target-changing event identifier to avoid mismatching of data from different rounds.

[0037] The high-voltage controller is connected to the indexing drive and locking state interface, the excitation power supply of the micro-focus focusing coil, the insert drive mechanism, the energy spectrum sampling probe, the target plate cooling channel and the electron gun assembly, respectively, to perform status acquisition, correction and beam exit permission during target change.

[0038] For each target region identifier, the high-voltage controller maintains a set of calibration parameters. This set includes at least the target characteristic spectral lines, initial tube voltage, initial beam current, initial focusing current, initial filter insertion depth, peak allowable window, focus allowable window, and upper temperature allowable limit. The calibration parameter set uses the target region identifier as an index and stores the generation date or version. If any necessary parameter is missing, the controller maintains the inability to perform effective exposure and proceeds to recalibration, without copying the missing value from other target regions.

[0039] The high-voltage controller establishes a joint status record for this target change. The joint status record includes at least the target area identification, lock-in status, energy spectrum peak position, focal spot position, focal spot size, filter insertion depth, target surface temperature, cooling status, vacuum status, and sampling time for each status.

[0040] Before starting the target area switching, the high-voltage controller revokes the valid exposure permission, preventing the rays generated during the switching and calibration phases from being used as official exposure data. The valid exposure prohibition state remains in place until all permission conditions are confirmed by this measurement.

[0041] The controller first determines the target characteristic spectral line based on the target absorption edge of the material being tested, then selects the target material region with the corresponding characteristic spectral line, and reads the calibration parameter group corresponding to the target region identifier.

[0042] After the indexing mechanism drives the target disk to the target position, the locking mechanism restricts the rotation of the target disk. The controller reads the target area markings and the locking status; if either piece of information is missing or the two do not correspond, the electron beam calibration stage is not initiated.

[0043] After the lock-up status is confirmed, the controller establishes the cooling conditions for the current target area and checks the vacuum status. If the temperature, cooling flow rate, or vacuum status does not meet the preset conditions, the electron gun assembly will not emit a beam.

[0044] After cooling and vacuum conditions are met, the quasi-monochromatic filter insert is first positioned in the calibration location. The electron gun assembly uses the initial tube voltage, beam current, and focusing current of the current target area to generate the calibration beam, reducing interference from the filtering state on the initial judgment of the target area and focus. The beam current and duration of the calibration beam should be sufficient to obtain the focal image and energy spectrum, while being lower than the formal exposure conditions or constrained by dedicated calibration conditions, to avoid applying unnecessary thermal load to the target surface before calibration is completed.

[0045] The focal imaging channel acquires the focal image. The high-voltage controller compares the focal position and size with the allowable focal window and adjusts the excitation current of the micro-focal focusing coil. If the focal point is not qualified, the system remains in an effective exposure-prohibited state. Focal correction saves at least the original focal position, focal size, focusing current, and the corresponding corrected values, allowing the system to determine if the correction direction matches the focal change.

[0046] The energy spectrum measurement channel acquires the energy spectrum peak position under the reference filtering state. If the energy spectrum peak position indicates that the current characteristic spectral line does not correspond to the selected target area, the controller stops calibrating the beam output and re-executes the target area transposition and lock-in confirmation, without masking the target area error by changing the filter depth.

[0047] After the target area and focus are confirmed, the insert driving mechanism brings the quasi-monochromatic filter insert to the initial insertion depth corresponding to the current target area, and the energy spectrum measurement channel again obtains the peak center, peak width, and flux. After the insert is driven into place, the measured insertion depth and the energy spectrum sampling results are written into the joint state record using the same sampling period, which can distinguish between insufficient driving and incompatibility of the filter material itself.

[0048] The high-voltage controller adjusts the filter insertion depth or tube voltage based on the measured deviation of the spectral peak from the target characteristic spectral line. After each round of energy spectrum correction, the focus state is checked to identify the impact of tube voltage changes on the electron beam focusing operating point.

[0049] During calibration, target area marking and locking status are mechanically permissible conditions, focal position and focal size are electro-optical permissible conditions, spectral peaks and filter depth are energy permissible conditions, and target surface temperature, cooling, and vacuum are safety permissible conditions. Each permissible condition retains its set value, measured value, and judgment result. When multiple states exceed their limits simultaneously, the state that first exceeds the limit is used as the diagnostic entry point, but all permissible conditions must still be reviewed after recovery.

[0050] Only when all the above-mentioned permitting conditions are within the corresponding allowable window, and the status value obtained after this target change is used, will the high-voltage controller lift the effective exposure prohibition status. Historical qualified values ​​cannot replace the current status confirmation.

[0051] To reduce misjudgments caused by the coupling of multiple control variables, it is preferable to perform the calibration in the order of target area confirmation, focus correction, and energy spectrum correction. Before starting the next stage, the qualified state of the previous stage should be saved. If the next stage causes the previous state to exceed the limit, the calibration should be returned to the corresponding stage for recalibration. This order does not require that only one value be adjusted in each stage, but rather that the main calibration object and return conditions be clearly defined, so that any adjustment can point back to the measured deviation of that adjustment.

[0052] Target surface temperature is continuously monitored during calibration and effective exposure. When the temperature approaches the allowable upper limit, the beam current can be reduced or the cooling flow rate increased; when the temperature exceeds the allowable upper limit, the electron gun assembly stops beam emission, and the target lock and focus status are rechecked after the temperature recovers.

[0053] When any of the following occurs: incorrect target area identification, loss of lock-up status, excessive peak deviation, excessive focus, incomplete filter insertion, excessive target surface temperature, abnormal cooling, or abnormal vacuum, the controller will revoke the valid exposure permission and record the first excessive state.

[0054] For anomalies that cannot be corrected by the current control input, the controller retracts the multi-target area rotation target disk back to the preset safe target area. The safe target area is used to keep the electron beam in a stopped bombardment or low-risk calibration position, preventing the abnormal target area from remaining in the effective exposure position.

[0055] After returning to the safe target area, the controller re-establishes lock-up, cooling, and vacuum conditions, and then performs recalibration in the order of target area confirmation, focus correction, and energy spectrum correction. The recalibration data uses a new event identifier and is not mixed with the data from before the limit was exceeded.

[0056] Each valid exposure is associated with and saved along with the corresponding set of calibration parameters and a joint status record. This allows for confirmation during subsequent verification of which target region, focal state, filter depth, and temperature and vacuum conditions a particular set of exposure data originated from. The joint status record may also include a task number, calibration or valid exposure flag, and anomaly code; this information serves to verify data attribution without altering the physical control relationships of the apparatus.

[0057] The allowable peak window, allowable focal spot window, upper limit of temperature, and allowable error of target disk rotation angle are set according to the target area, measurement accuracy, and application task. In one set of embodiments, the peak center deviation is no greater than 2% of the target value, and the target disk rotation angle error is no greater than 20 μrad.

[0058] The number of target regions, tube voltage, and focal spot size are selected based on the application of the X-ray source. Within the original technical range, the number of target regions can be 3 to 12, the tube voltage can be 15 kV to 160 kV, and the focal spot size can be 0.5 μm to 15 μm; these ranges are used to describe the operating boundaries and do not imply that all combinations can be used without calibration. For example, at the same tube voltage, different target regions still need to have their characteristic peaks, focal spots, and thermal states verified separately; the listed ranges should not be interpreted as arbitrarily combining any target with any operating point.

[0059] By using target area identification and locking status as prerequisites for beam output permission, we can avoid judging whether the target area is in place based solely on motor command values, thus reducing the risk of incorrect target areas corresponding to incorrect characteristic spectral lines.

[0060] By re-acquiring the focal image and adjusting the focusing current after target replacement, the effects of target position difference and rotation hysteresis on focal position and focal size can be incorporated into the current correction, avoiding the direct use of the focusing parameters of the previous target area as the final parameters.

[0061] By first completing the target area and focus correction, and then correcting the filter depth and tube voltage according to the actual energy spectrum, mechanical or electro-optical deviations can be distinguished from filter deviations, reducing attribution confusion caused by the simultaneous changes of multiple control quantities.

[0062] Through effective exposure gating, data generated during the calibration phase and in over-limit states are not included in the formal exposure sequence; only beams confirmed by this joint state are marked as valid outputs. The gating signal should also correspond to the frame identifier of the acquisition system, so that calibration frames, over-limit frames, and valid exposure frames can be distinguished from the records, preventing misalignment between control permission and data reception.

[0063] With a safe target area and recalibration path, the system has a clear retreat boundary when recovery from the current operating point is not possible, avoiding continued electron beam application when the lock-up, cooling, or vacuum conditions are uncertain. After the target retreat command is issued, the electron gun assembly remains stopped emitting beams until the safe target area marking, lock-up, cooling, and vacuum conditions are all reconfirmed; this sequence separates anomaly isolation from subsequent recalibration, preventing the recovery action itself from creating new unconfirmed exposures.

[0064] First, select the target area according to the target absorption edge and obtain the calibration parameter group corresponding to the target area identifier. Then, complete the inversion lock and status check under the effective exposure prohibition state.

[0065] The focus and energy spectrum are then obtained by calibrating the beam. The state is brought into the corresponding allowable window through controlled correction of the beam current, filter insertion depth and tube voltage. Effective exposure can only begin after all allowable conditions are met.

[0066] If any state exceeds the limit, effective exposure is stopped and the state that first exceeded the limit is identified. If the current control variable cannot be recovered, the system returns to the safe target area and is recalibrated, thus clearly demarcating the normal and abnormal paths. Near the boundary of the allowable window, the controller may use consecutive multiple samplings in agreement or maintain a specified stabilization time as additional permission conditions; the additional conditions should be saved for the current target area and may not be used to replace target area identification and lockout status verification.

[0067] Multi-target area transposition target disks can be in the form of circumferential sectors, annular partitions of the same radius, or planar arrays that can send different target areas to a common bombardment position, as long as the target area identification, locking status and the current target area can correspond one-to-one.

[0068] The quasi-monochromatic filter insert can be a single variable insertion depth structure or multiple filter materials forming a selectable equivalent depth; regardless of the form, the controller obtains the measured filter state and corresponds it to the energy spectrum measurement value.

[0069] The energy spectrum measurement channel and the focal imaging channel can be integrated into a single sampling probe, or they can be two channels of a common sampling component; both should be triggered by the same target change event and write the results into the same joint state record.

[0070] The high-voltage controller can consist of a motion control unit, a beam control unit, an energy spectrum processing unit, and a high-voltage power supply control unit that communicate with each other. This functional division does not alter the relationship between the various state variables that jointly determine the effective exposure permit. If the sampling frequencies of the two channels are different, the joint state record saves their respective sampling times and only forms a set of judgment quantities within a specified synchronization window; if the synchronization window is exceeded, resampling is performed, and the measured state required for the permit is not generated by interpolation.

[0071] Under the condition that the relationship between the original record and the attached figures is met, the specific driving form, cooling medium or target combination can be changed; however, if any of the key relationships in target area confirmation, focus and energy spectrum verification after target change and effective exposure gating are missing, it does not belong to the cooperative control chain emphasized in this case.

[0072] The effects of the above technical solutions derive from the interplay of mechanical, electro-optical, energy, and safety conditions, rather than the simple sum of the performance of individual components. Each effect should be verified against corresponding state records or calibration results, and should not be replaced by unverified, promotional conclusions.

[0073] The focus of this invention is on establishing the joint state and the phased calibration relationship after target replacement. Specific parameter endpoints can be determined by the range of the implementing equipment, the target material, and the application task, and recorded in the calibration parameter set described in the specification.

[0074] Those skilled in the art can make equivalent adjustments to the specific implementation of the target disk driver, filter driver, and control unit without changing the above-mentioned core relationships; these adjustments should still satisfy the structural connection, state acquisition, and beam exit licensing relationships defined in the claims.

[0075] Compared to devices that simply switch predetermined filters based on target area numbers or reuse calibration parameters from before target change, this invention differs in that it constrains the order of target area confirmation, focus correction, energy spectrum correction, and safety clearance acquisition with the same target change event, binding each state to the current measured value, and only releasing the effective exposure prohibition state after all permission conditions have been confirmed by the current measurement. The technical problem this distinguishing feature actually solves is: how to ensure that the beam entering the imaging sequence truly originates from the selected target area and its corresponding calibration parameter set when the mechanical, electro-optical, energy, and thermal safety states are mismatched after target change. Regarding this technical problem, the combination verification of target area identification and locking status eliminates the illusion that the motor has stopped before the rotation is stable; the order of completing focus correction first, then energy spectrum correction, and then verifying the focus after tube voltage correction avoids attribution confusion caused by simultaneous changes in multiple control quantities; and effective exposure gating allows calibration frames, out-of-limit frames, and effective exposure frames to be distinguished in the data record.

[0076] It should be noted that, in order to improve equipment utilization after target replacement, the conventional practice in this field is to directly call historical calibration results and use the in-situ reports of each local closed loop as the basis for permission to quickly restore beam output. The approach taken in this case is the opposite of this conventional practice: after target replacement, the valid exposure permission is revoked first, and the focus and energy spectrum state are re-obtained with a calibrated beam output under conditions lower than the formal exposure conditions. Any permission conditions remain prohibited unless confirmed in this instance. Implementing this in the opposite direction does not reduce the effective output of the equipment: abnormal states are isolated from the valid exposure sequence, and the machine time occupied by rework, reshoots, and error data backtracking is correspondingly reduced. This effect stems from the mutual constraints between various state variables and cannot be expected from improving any one of the target disk positioning accuracy, focusing power supply accuracy, or filter drive accuracy individually. Attached Figure Description

[0077] Figure 1 The relative arrangement and control connections of the electron gun assembly, multi-target rotation target disk, microfocus focusing coil, quasi-monochromatic filter insert, energy spectrum sampling probe and vacuum-sealed housing at the source end are shown.

[0078] Figure 2 The assembly relationship of the target material numbering area, indexing bearing, locking pin, cooling inlet, cooling circuit and thermal sensor is shown along the target disk rotation axis.

[0079] Figure 3 The staged closed-loop relationship between target energy, target area command, energy spectrum peak position, focal image, filter depth and high voltage correction is shown.

[0080] Figure 4 The control path is shown, starting from the selection of the target material absorption edge, through target area transposition, tube voltage and beam current setting, filter insertion, spectral peak sampling, joint correction to effective output, and retreating to the safe target area and recalibrating after exceeding the limit. Detailed Implementation

[0081] The structure and operation of the present invention are described below with reference to the accompanying drawings. The embodiments described are intended to enable those skilled in the art to understand and implement the synergistic relationships defined in the claims; accuracy or effects without original experimental evidence are not presented as verified facts. The same reference numerals in the drawings denote the same objects.

[0082] Example 1: Multi-target source structure, state interface and target-by-target calibration

[0083] See Figure 1The device includes an electron gun assembly 101, a multi-target rotation target disk 102, a microfocus focusing coil 103, a quasi-monochromatic filter insert 104, an energy spectrum sampling probe 105, a vacuum-sealed housing 106, a target disk cooling channel 107, and a high-voltage controller 108. The electron gun assembly 101, the multi-target rotation target disk 102, and the microfocus focusing coil 103 are located inside the vacuum-sealed housing 106, and X-rays are output outward through the beam exit window of the housing.

[0084] The electron gun assembly 101 arranges the cathode, focusing electrode, and anode structures along the electron beam path. An external electron gun control power supply provides heating, bias, and acceleration conditions. The high-voltage controller 108 allows the electron beam to reach the target surface only after receiving beam exit permission; during rotation and recalibration, beam exit is restricted to either a stopped state or a calibrated beam exit state. The specific electrode shape of the electron gun assembly can be determined according to existing electron optics designs, but the high-voltage controller must be able to distinguish between the three states of stopped beam exit, calibrated beam exit, and effective exposure, and record the state transition in the event log.

[0085] The outer periphery of the multi-target zone transposition target disk 102 is provided with multiple target material zones of different materials. Figure 1 Simplified in sector form, Figure 2 The target numbering area 201 is further shown. Each number corresponds to the actual target, the target characteristic spectral line, and a set of initial control parameters. This correspondence is verified after assembly and maintenance.

[0086] See Figure 2 The multi-target zone indexing target disk 102 is supported by indexing bearings 202, and locking pins 203 engage with the locking position on the target disk. After the indexing drive stops, the locking pins 203 enter the corresponding position; the controller simultaneously reads the target material number area 201 and the locking status, and does not use the fact that the motor has stopped as the sole basis for target zone confirmation. After the locking pins 203 enter, a locking signal can also be given by limit contacts or position detection structures; if the number is read correctly but the locking signal is missing, the controller still determines that the target zone has not been confirmed.

[0087] The beam-receiving surfaces of each target region are arranged as close as possible to a common bombardment radius and a common nominal focal plane. The residual positional differences caused by manufacturing and assembly are not eliminated by assumption, but are converted into the initial focusing current and focal allowable window of the target region during target-by-target calibration.

[0088] Cooling inlet 204 supplies cooling medium to target plate cooling channel 107. The cooling medium flows along cooling circuit 205 across the back of the target area and returns. Thermal sensor 206 detects the temperature of the target plate body or the adjacent currently receiving target area, and high-voltage controller 108 adjusts the cooling flow rate, limits the beam current, or stops beam output accordingly. The specific cross-section and medium of the cooling circuit are determined by thermal design; the control logic uses the measured temperature and cooling status as permissible conditions.

[0089] The microfocus focusing coil 103 is located between the electron gun assembly 101 and the multi-target area rotation target disk 102. When its excitation current is changed, the landing point and focal size of the electron beam on the current target area change. Target-by-target calibration records the initial excitation current that allows the focal point to enter the allowable window, without requiring all target areas to share a single final value.

[0090] The quasi-monochromatic filter insert 104 is located on the X-ray path inside or outside the beam exit window, and its insertion depth is changed by a linear drive. The insertion depth feedback device returns the measured position; the controller compares the commanded position and the measured position, and does not regard "drive command sent" as "filtering status in place". To verify the drive hysteresis, the initial insertion depth can be approached from two directions in the same target area and the measured position can be recorded; if the difference between the two positions exceeds the allowable range, effective exposure will not be opened before recalibration.

[0091] The energy spectrum sampling probe 105 is arranged in the sampling branch that can receive the emitted X-rays. Figure 3 The energy spectrum peak 303 in the image comes from the energy spectrum measurement channel, and the focal image 304 comes from the focal imaging channel. Data from both channels are acquired in the same calibration event and correlated with the current target region identifier, lock-in status, and sampling time.

[0092] The high-voltage controller 108 may include motion control, beam focusing control, filter drive, energy spectrum processing, and high-voltage power supply control functions. These functions may be located in the same control device or distributed among interconnected units; regardless of their hardware configuration, beam output permission is uniformly determined by the same joint status record.

[0093] During target-by-target calibration, a target area is first selected and locked, cooled, and vacuumed. Then, the quasi-monochromatic filter insert 104 is positioned at the reference location. The electron gun assembly 101 operates at a lower or specified calibration beam current, and the energy spectrum sampling probe 105 acquires the initial focal image 304 and the energy spectrum peak position 303. During the target-by-target calibration process, the waiting conditions required for the focal image and energy spectrum to stabilize after locking are also recorded; subsequent target changes must not use historical results before the corresponding stabilization conditions are met.

[0094] The controller first adjusts the microfocus focusing coil 103 to bring the focus position and size into the allowable focus window of the target area; then it drives the quasi-monochromatic filter insert 104 to the initial insertion depth and corrects the filter depth or tube voltage according to the measured spectral peaks, spectral width, and flux. Before saving the target area calibration parameters, at least one round of retreat and re-entry can be repeated to check whether the lock-in, focus, and filter states can return to the same allowable window; if the repetition result is unsatisfactory, the set of parameters is not marked as usable.

[0095] After each filter depth or tube voltage correction is completed, the focus image 304 is rechecked. If the focus state exceeds the limit due to changes in the electron energy operating point, the focus correction is returned; this results in controlled iteration of the focus and energy spectrum, rather than simultaneously and disorderly changing all control variables.

[0096] After calibrating one target region, save the target region identifier, target characteristic spectral lines, tube voltage, beam current, focusing current, filter insertion depth, peak allowable window, focal allowable window, upper temperature limit, and vacuum permitting conditions. Other target regions should be calibrated using the same steps, ensuring that the parameters do not overlap.

[0097] In this embodiment, three or more target regions can be formed using different target materials such as tungsten, molybdenum, and copper. The specific target combination is determined by the absorption edge of the material being measured and the operating energy of the equipment; the target name itself does not replace the calibration of the target position, focal point, filtering, and thermal state.

[0098] When calibration data is insufficient, only the structural relationships and parameters that have been obtained and can be verified should be written into the calibration parameter group.

[0099] Example 2: Staged Focus-Spectrum Correction and Effective Exposure Gating after Target Change

[0100] See Figure 4 In step 401, the target energy is determined based on the target absorption edge of the material under test, and a target area with corresponding characteristic spectral lines is selected. The high-voltage controller 108 reads the calibration parameter group corresponding to the target area identifier and simultaneously cancels the valid exposure permission of the previous target area.

[0101] Step 402 drives the multi-target area rotation target disk 102 to rotate to the target target area. After rotation, the locking pin 203 enters the locking position; the controller compares the identification result of the target number area 201, the target target area command 302, and the locking state. If the three are inconsistent, the calibration beam output will not be initiated. During the rotation process, the electron gun assembly remains stopped from outputting beams, and the quasi-monochromatic filter insert is positioned so as not to be mistaken for the current final filtering state; thus, target area confirmation does not depend on the filtered spectral shape.

[0102] After lockout confirmation, the cooling circuit 205 is activated or confirmed, the thermal sensor 206 is read, and the vacuum status of the vacuum-sealed housing 106 is checked. If cooling is not established, the target temperature exceeds the limit, or the vacuum status does not meet the permissible conditions, the electron gun assembly 101 remains stopped emitting beams.

[0103] Step 403 provides the initial tube voltage, beam current, and focus current according to the current calibration parameter set. This stage is for calibration only and is not part of the formal exposure; the calibration data has a calibration identifier and cannot be mixed with valid exposure data after joint status clearance.

[0104] A focal image 304 is acquired when the filter insert is in the reference position. The controller obtains the offset of the focal center relative to the calibrated position and the focal size from the focal image, and adjusts the excitation current of the micro-focal focusing coil 103 accordingly until the focal state enters the allowable window.

[0105] After focus correction is completed, the energy spectrum peak position 303 under the reference state is obtained. If the characteristic peak does not correspond to the target target, it is first determined whether the target region selection or locking is incorrect, the beam output calibration is stopped and the process returns to step 402; the incorrect target region is not disguised as the target target region by significantly changing the tube voltage or filtering depth. The reference energy spectrum is used to confirm whether the target characteristic peak exists in the expected region, rather than requiring the unfiltered spectrum shape to meet the final quasi-monochromatic window; the final spectrum shape is determined separately after filtering is in place.

[0106] Step 404: Drive the monochrome filter insert 104 to the initial insertion depth of the current target area and obtain insertion depth feedback. If the feedback is not in place, maintain the effective exposure prohibited state, re-drive, or report an insert execution error.

[0107] Step 405 involves resampling the energy spectrum peak position after the filter is in place. The energy spectrum measurement channel simultaneously acquires at least two of the following: peak center, peak width, and flux, to avoid ignoring the effective flux loss caused by excessive filtering based on only a single peak position.

[0108] Step 406 compares the measured spectral peaks with the target characteristic spectral lines. Figure 4 A criterion is set at a peak center deviation of no more than 2% of the target value. Other devices can determine their respective allowable windows based on resolution and application tasks, but the criterion must belong to the current target area calibration parameter group. The target value, measured value, allowable window, and decision time are saved simultaneously during the judgment process. Even if the value is acceptable, if the sampling time is earlier than the current lockout confirmation or comes from another calibration version, it cannot be used as the basis for this approval.

[0109] When the spectral peak deviation is mainly manifested as unacceptable spectral shape or flux after filtering, the filter insertion depth should be adjusted in small steps first. When the characteristic peak position is related to the electron energy operating point and the filter adjustment cannot recover, the tube voltage should be corrected within the allowable range of the target region. Single change boundaries are set for both the filter depth and tube voltage correction to prevent a large correction from crossing the stable operating region at once. If the correction still fails to meet the requirements after reaching the boundary, the abnormal path should be entered instead of continuing to accumulate corrections.

[0110] Figure 3 The high-voltage correction amount 306 in the figure represents the correction result of the high-voltage controller 108 to the tube voltage operating point. The focus image 304 is reacquired after each high-voltage correction because changes in tube voltage may alter electron beam transmission and focusing state.

[0111] If the focus verification exceeds the limit again, the controller returns to the focus correction stage to adjust the focusing current; the energy spectrum is obtained again after the focus is qualified. This sequence ensures a clear return relationship between focus correction and energy spectrum correction, and retains the state values ​​before and after each correction.

[0112] When the target area identification and locking status are correct, the focal position and size are qualified, the filter insertion depth is in place, the energy spectrum peak position is qualified, the target surface temperature is qualified, and the cooling and vacuum status are qualified, step 407 completes the closed-loop confirmation of the focal point and energy, and the high-voltage controller 108 then issues a valid exposure permit. After the permit is generated, it is accompanied by the target area identification and status record index for this exposure; the acquisition system receives this index before marking the formal exposure frame to avoid misalignment between the controller permit and the image acquisition start frame.

[0113] During valid exposure, the controller continues to monitor target lock, energy spectrum, focus, filtering, temperature, cooling, and vacuum status. If any status exceeds its limit, the valid exposure permission is revoked; frames following revocation are not included in the valid results, and formal exposure is not automatically resumed until reconfirmed.

[0114] Step 408 involves associating and saving parameters such as tube voltage, beam current, energy, focal depth, and exposure time corresponding to different target regions with the target region identification and calibration version. This table is used to verify the exposure conditions for this test and does not record uncalibrated estimated values ​​as measured results.

[0115] When switching to the next target area, first end the current valid exposure and save the current state, then start again from step 401. The next target area only uses its own calibration parameter group; the qualified state of the previous target area cannot be directly used as the beam output permission for the next target area.

[0116] Example 3: Limit Exceedance Diagnosis, Safe Target Retrieval, Recalibration, and Failure Boundary

[0117] If the peak position of the energy spectrum exceeds the limit during operation, the controller first checks the target area identification, locking status, and filter insertion depth. If the target area or locking is incorrect, it is handled as a mechanical abnormality; if the target area is correct but the filter position is not in place, the insert drive is checked; only after both are correct can the tube voltage be corrected within the allowable range. The diagnostic sequence for exceeding the energy spectrum limit is used to prevent misjudging incorrect target area selection as filter deviation; each level of inspection has corresponding actual measurements and cannot rely solely on the operator's written confirmation.

[0118] If the focal position or focal size exceeds the limit, the controller checks the current focusing current, tube voltage, and target lock status. If the focusing current cannot be restored by small adjustments, the adjustment is not expanded further; instead, the abnormality is classified as requiring target removal and recalibration.

[0119] If the thermal sensor 206 reports that the target surface temperature is close to the upper limit, the beam current can be reduced or the cooling flow rate can be increased. If the temperature exceeds the upper limit or the cooling circuit 205 fails, the electron gun assembly 101 should be stopped from emitting beams immediately, and the target disk should be kept locked for controlled cooling.

[0120] If the vacuum condition is abnormal, the controller will not perform target rotation, focusing, or filtering correction to mask the abnormality, but will directly prevent the electron gun assembly 101 from emitting the beam. After the vacuum is restored, the target lock, focus, and energy spectrum still need to be rechecked.

[0121] All anomalies are recorded with the initial state of exceeding the limit, the target area identification at that time, tube voltage, beam current, focusing current, filter insertion depth, target surface temperature, and vacuum status. Subsequent corrections add new states on a time-based basis, without overwriting the original records at the time of the anomaly.

[0122] For minor deviations that can be recovered at the current operating point, the controller must verify other permitting conditions after correcting the affected stage. Only when all conditions are restored to compliance can a new valid exposure permit be generated. If multiple states exceed limits within the same sampling period, all states are written into the anomaly log, and the recovery order is determined according to the relationship between mechanical permit, safety permit, focus permit, and energy permit.

[0123] For anomalies that cannot be recovered at the current operating point, proceed to step 409. The high-voltage controller 108 stops calibrating the beam output, drives the multi-target area indexing target disk 102 to leave the abnormal target area and enter the preset safe target area, and then confirms the identification and locking status of the safe target area.

[0124] A safe target area can be a dedicated, unconstrained location or a target area that has been verified to withstand calibration conditions. Its specific form is determined by the equipment structure, but the purpose of entering the safe target area is to prevent abnormal target areas from continuing to receive formal bombardment.

[0125] Step 410: Under safe conditions, re-establish the rotation reference, locking reference, beamforming reference, filter position reference, energy spectrum reference, and temperature reference. When only reconstructing parameters affected by the anomaly, also verify that the remaining permissible conditions still belong to the current calibration version.

[0126] During recalibration, the quasi-monochrome filter insert 104 is first placed in the reference position, the focal image is obtained, and the microfocus focusing coil 103 is corrected; then the energy spectrum is obtained, the filter is inserted, and the energy spectrum correction is completed, in the same order as in Example 2. The re-established reference uses a new calibration version number; any cached parameters that still refer to the old version are marked as unusable for this round of effective exposure, but can be retained for fault comparison.

[0127] Step 411 resamples the energy spectrum peak position, simultaneously acquiring the focal image and filtering depth feedback. Once the new result meets the current target area's allowable window, a new joint state record is formed; its event identifier differs from the record before the limit was exceeded. Before resampling, it is also checked whether the sampling time of the energy spectrum channel and the focal imaging channel is later than the relocking time; data earlier than this time are retained as fault records but do not participate in the new permission judgment.

[0128] If the same anomaly occurs repeatedly within the preset number of retries, the controller will maintain the inability to perform effective exposure and output a pending maintenance status, without forcibly opening the beam by expanding the allow window or ignoring the failure channel.

[0129] When comparing data before and after exceeding limits, only data with clear target area identification, calibration version, and joint state record should be compared. Data lacking any one of the following—target area, focus, spectral peak, filtering, or thermal state—is not used to demonstrate that the device has achieved a specific level of accuracy.

[0130] The multi-target area rotation target disk 102 can employ different driving methods, and the quasi-monochrome filter insert 104 can be inserted linearly as a single piece or combined with multiple pieces at equivalent depth. The replacement structure should still output the actual target area, lock-up, and filter status, and accept the same effective exposure gating. If the replacement structure changes the method of obtaining target area recognition or filter position feedback, the correspondence between its sampling time and the current target area should be re-verified; the old calibration cannot be used simply because the component names are the same.

[0131] The calibration priority can be adjusted according to the coupling characteristics of the equipment, but target area confirmation must not be omitted, and effective exposure must not be opened if the focus and energy spectrum have not been verified in this test. The adjusted sequence should be fixed in the calibration parameter group and can be verified by the mission record.

[0132] The failure boundaries defined in this embodiment include: unknown state origin, mismatch between lockout and target area, missing necessary measurements, non-convergence of calibration, and inability to recover temperature or vacuum. When any of these boundaries is reached, the device remains inactive, awaiting repair or confirmation of new implementation guidelines.

[0133] In one implementation scheme, the synchronization window for each state within the same target change event in the joint state recording is set to no more than two sampling cycles; the allowable deviation of the spectral peak center is set to 2% of the target value, the allowable error of the target disk rotation angle is set to 20 μrad, the allowable deviation of the focal position is set to one-tenth of the current focal size, and the allowable upper limit of the target surface temperature is set separately for each target material region. The recovery criteria after returning to the safe target area are set as follows: confirmation of the safe target area identification and locking status, re-establishment of cooling and vacuum permission, and both the focal point and energy spectrum are qualified according to the current data. Only when all three conditions are met will a new valid exposure permission be generated; if the same abnormality occurs three times consecutively, the device will enter a maintenance state and remain prohibited from valid exposure. The values ​​of the above criteria can be adjusted according to the equipment range and task requirements, but each criterion is bound and saved with the current target area identification and calibration version.

Claims

1. A switchable target quasi-monochromatic microfocus X-ray source device, characterized in that, The system includes an electron gun assembly, a multi-target area indexing target disk, a micro-focusing coil, a quasi-monochromatic filter insert, an energy spectrum sampling probe, a target disk cooling channel, a high-voltage controller, and a vacuum-sealed housing. The multi-target area indexing target disk is housed within the vacuum-sealed housing and has at least two target areas with different target materials, target area markers for distinguishing the target areas, and an indexing and locking mechanism for maintaining the selected target area at the electron beam bombardment position. The micro-focusing coil is located between the electron gun assembly and the multi-target area indexing target disk. The quasi-monochromatic filter insert is driven by an insert driving mechanism to change its insertion depth in the X-ray beam exit path. The energy spectrum sampling probe has an energy spectrum measurement channel for outputting the energy spectrum peak position and a focus imaging channel for outputting the focus position and focus size. The target disk cooling channel is connected to the current target area. The target area of ​​the beam is thermally connected; the high-voltage controller is connected to the electron gun assembly, the multi-target area shifting target disk, the micro-focus focusing coil, the insert drive mechanism, the energy spectrum sampling probe, and the target disk cooling channel, and is configured to maintain an effective exposure prohibition state after the target area is switched. It obtains the target area identification and locking state, energy spectrum peak position, focus position, focus size, filter insertion depth, and target surface temperature corresponding to this switch. It compares the obtained state with the calibration parameter group corresponding to the selected target area and controls at least one of the multi-target area shifting target disk, the micro-focus focusing coil, the insert drive mechanism, and the electron gun assembly to perform correction. The effective exposure prohibition state is released only after the target area locking, energy spectrum peak position, focus state, filter insertion depth, target surface temperature, cooling state, and vacuum state all meet their respective allowable conditions.

2. The apparatus according to claim 1, characterized in that, The multi-target area indexing target disk includes a target disk body, indexing bearings, locking pins, and multiple fan-shaped target areas arranged circumferentially along the target disk body. The receiving surface of each target area is located at the same electron beam bombardment radius. The target area identifier is fixedly corresponding to the corresponding target area. When the locking pin enters the corresponding locking position, a locking status signal is generated. The high-voltage controller confirms the current receiving target area based on the combination of the target area identifier and the locking status signal.

3. The apparatus according to claim 1, characterized in that, The target cooling channel includes a cooling inlet, a cooling circuit extending along the back of the target area, and a thermal sensor for detecting the temperature of the target body. The high-voltage controller adjusts the cooling flow rate according to the tube current and temperature detection value corresponding to the current target area, and reduces the beam current or stops the electron gun assembly from emitting beam when the temperature detection value exceeds the allowable upper limit of the corresponding target area.

4. The apparatus according to claim 1, characterized in that, The insert driving mechanism includes a linear drive and an insertion depth feedback component; the high-voltage controller first positions the quasi-monochromatic filter insert in the calibration position to complete the target position and focus correction, then moves the quasi-monochromatic filter insert into the initial insertion depth corresponding to the selected target material area, and corrects the insertion depth according to the deviation of the energy spectrum peak position relative to the target characteristic spectral line.

5. The apparatus according to claim 1, characterized in that, The energy spectrum measurement channel outputs at least two of the following: peak center, peak width, and flux. The focal imaging channel outputs the position and size of the focal spot formed by the electron beam bombardment. The high-voltage controller associates and saves the position and size of the peak center and focal spot with the current target area identifier, tube voltage, focusing current, and filter insertion depth. After target change, the calibration only calls the calibration parameter group corresponding to the current target area identifier.

6. The apparatus according to claim 1, characterized in that, The high-voltage controller performs post-target-change calibration in the order of target area confirmation, focus calibration, and energy spectrum calibration. Target area confirmation includes at least verifying the target area identification and locking status; focus calibration includes at least adjusting the excitation current of the micro-focus focusing coil according to the focus position or focus size; and energy spectrum calibration includes at least adjusting the insertion depth of the quasi-monochromatic filter insert or the tube voltage of the electron gun assembly according to the energy spectrum peak position. The qualified status of the previous calibration stage is saved before the next calibration stage begins.

7. The apparatus according to claim 1, characterized in that, When any of the following occurs, the high-voltage controller maintains an effective exposure prohibition state, controls the multi-target area rotation target disk to return to the preset safe target area, and re-acquires the energy spectrum peak position and focus state after the locking, cooling and vacuum conditions are re-established.

8. The apparatus according to claim 1, characterized in that, The calibration parameter group stores target characteristic spectral lines, tube voltage, beam current, focusing current, filter insertion depth, peak allowable window, focal point allowable window, and temperature allowable upper limit according to the target area identification; the multi-target area transposition target disk has 3 to 12 target areas, the tube voltage of the electron gun assembly is in the range of 15kV to 160kV, and the focal point size is 0.5μm to 15μm.

9. An energy control method implemented using the device according to any one of claims 1 to 8, characterized in that: Select the target area based on the target absorption edge of the material being tested and read the calibration parameter group corresponding to the target area identifier; Effective exposure is prohibited. The multi-target area rotation target disk is driven to bring the selected target area into the electron beam bombardment position. After locking, the target area marking and locking status are checked. Cooling conditions corresponding to the selected target area are established and the vacuum status is confirmed. Set the tube voltage, beam current, and focusing current according to the calibration parameter set to calibrate the beam and obtain the focal position, focal size, and energy spectrum peak position; adjust the focusing current according to the focal state, and adjust the filter insertion depth or tube voltage according to the energy spectrum peak position; open effective exposure after the target area lock, focal state, energy spectrum peak position, filter insertion depth, target surface temperature, cooling state, and vacuum state all enter their respective allowable windows; stop effective exposure and return to the safe target area for recalibration if any state exceeds the limit.

10. The method according to claim 9, characterized in that, The calibration after target change includes the following steps: S1. Place the quasi-monochrome filter insert in the calibration position and read the target area marking, lock-up status, target surface temperature and vacuum status under the effective exposure prohibition state. S2. The calibrated beam is formed using the initial tube voltage, beam current and focusing current corresponding to the current target area, the focal position and focal size are obtained, and the micro-focal focusing coil is adjusted until the focal state enters the focal allowable window; S3. Obtain the energy spectrum peak position under unfiltered or reference filtered conditions, and determine whether the target area corresponds to the target characteristic spectral line; if the correspondence is not established, stop the beam calibration and re-rotate and lock. S4. Make the quasi-monochromatic filter insert reach the initial insertion depth, re-obtain the energy spectrum peak position, correct the insertion depth and tube voltage according to the energy spectrum peak position deviation, and check the focus state after each correction. S5. When the deviation of the spectral peak center is no greater than 2% of its target value, the target disk rotation angle error is no greater than 20 μrad, and all other conditions are within the corresponding allowable window, open the effective exposure; otherwise, maintain the effective exposure prohibition state, return to the safe target area, recalibrate, and establish the correspondence between this data and the calibration parameter group.

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