CN116482867A - Automatic feedback dimming system and method for beam line station - Google Patents
Automatic feedback dimming system and method for beam line station Download PDFInfo
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Abstract
The invention relates to an automatic feedback dimming system of a beam line station, which comprises a local area network, a beam line system, an emergent slit system and an experiment station; the system parameter module is used for storing main adjusting parameters and feedback parameters of the dimming optical element in a table look-up mode parameter file; the automatic feedback control module obtains an influence rule of the change of the dimming parameter of the beam line system on the change of the feedback parameter according to the table lookup mode parameter file, reads out photocurrent signals of four knife edges of the emergent slit system in the feedback parameter in real time, and determines the current deviation of the current center of gravity of the emergent slit system relative to the opening center of the emergent slit system in real time; when the current deviation is larger than the set deviation threshold, the dimming parameter of the beam line system is automatically corrected. The automatic feedback dimming system can realize the collimation of the beam center and maintain the maximum luminous flux through automatic feedback, and can effectively improve the experimental efficiency and the quality of experimental data.
Description
Technical Field
The invention belongs to the operation control of a synchronous light source beam line station, and relates to an automatic feedback dimming system of a beam line station.
Background
The synchrotron radiation light source can provide the most advanced and irreplaceable tools for basic and application research in the subject fields of material science, life science, environmental science, physics, chemistry, medicine and pharmacology, geology and the like, and is applied to important and wide fields. The experimental station is a comprehensive technological platform for scientists and engineers to uncover scientific secrets and develop high and new technology products by utilizing synchronous radiation light.
The spectroscopy experiment is an experimental method for the important development of the synchrotron radiation light source, and can study the information of the valence state, the electronic structure and the like of the material. In order to increase the flux of the incident light and to remain constant, it is necessary to monitor the light flux and the center spot position in real time. For an in-situ spectroscopy experiment station, the center position of the strongest light spot is fixed, the opening of the emergent slit can be reduced, the energy resolution of incident light is improved, and the signal-to-noise ratio and the quality of the acquired spectral line are further improved. Meanwhile, the fixed position of the central light spot is also convenient for rapidly positioning a spectroscopy experiment sample, and has important significance for experiments on samples with micrometer sizes. And the automatic regulating device can monitor the change of the incident luminous flux in real time and perform automatic feedback correction, so that the stability of the experimental data quality is ensured.
The imaging experiment is another important experimental technical method of synchronous radiation, and can be used for two-dimensional and three-dimensional space imaging and element spectroscopy imaging and analysis, and particularly, the periodic lattice point array scanning imaging is more required to ensure the incident luminous flux and stable position, otherwise, bright and dark noise can be caused, so that the image quality is affected. For nanometer space resolution scanning coherent diffraction imaging, the light spot generated by the upstream light beam line is circular, the center is strongest, an emergent slit is arranged before the light spot reaches the sample, the opening size is smaller than 50 microns, and the strongest light spot at the downstream sample can be ensured to be strongest only when the strongest light spot passes through the slit, so that the collected sample signal is ensured to be strong, and the signal to noise ratio is improved. Theoretically, the central light spot position of the upstream light beam line is fixed relative to the downstream sample, so that the light spot density incident on the zone plate can be ensured to be as uniform as possible, the strongest central light spot can pass through the slit through the gesture adjustment of the upstream optical element, the strongest central light spot can reduce the opening size of the emergent slit, the spatial coherence of incident light is improved, and finally the influence of incoherent factors on imaging quality and spatial resolution is weakened or even eliminated, thereby improving imaging resolution. If the central light deviates, the light intensity of the irradiated sample is weakened, and when the light intensity is serious, the light cannot be irradiated on the sample, so that the experimental quality is poor, and even the experiment cannot be carried out.
However, at present, in a real experiment, the position of a downstream central light spot is changed due to adjustment or shake of an upstream various optical element gesture movement mechanisms (motors), and the position of the central light spot of an upstream light beam line cannot be ensured to be fixed relative to a downstream sample.
At present, different kinds of experiments carried out by different users relate to sample switching, incident light energy changing and the like, and synchronous adjustment and matching of corresponding parameters of a light beam line and the posture of an optical element are required. In order to realize and keep the central strongest light spot to be incident to the sample, the gesture of each optical element at the upstream is required to be manually adjusted according to the experiment requirement before the experiment starts, and meanwhile, the signals of the related light intensity measurement on the downstream light path in the observation are adjusted to realize the strongest light at the sample.
Most of the steps are manually completed by experimenters, so that time and labor are wasted, and the experimental efficiency is severely limited. In addition, during the experiment, the instability of the accelerator and the deviation of the electron beam current track in the storage ring can cause the deviation of the center of the beam of the line station, and the posture of the optical element needs to be adjusted to correct the center of the light spot to the original position in real time. Especially for imaging experiments, the constant flux of light spots entering the sample is required to be ensured, the position is stable, most of the existing methods do not have automatic feedback correction, the light spots with the highest center can only be manually adjusted to enter the sample, if the center of the light spots is deviated in the experimental process, an operator is required to judge according to the reduction of the quality of experimental data, and then the position of the light spots at the center is manually adjusted and corrected again, so that the fixed and unchanged posture of the light spots is difficult to realize.
Therefore, it is necessary to develop an automatic feedback dimming device system for a beam line station, which monitors the fluctuation condition of the optical signal at the exit slit in real time, automatically corrects the related parameters of the beam line through the automatic feedback system to realize the collimation of the optical path and maintain the highest luminous flux on the sample, and has important significance for improving the absorption spectrum of the synchrotron radiation light source and the imaging experimental efficiency and improving the experimental quality.
Disclosure of Invention
The invention aims to provide an automatic feedback dimming device system of a beam line station, which can realize automatic feedback to realize beam center collimation and keep maximum luminous flux when the center of a light spot shakes greatly due to factors such as energy replacement, element switching, electron beam group fluctuation of a storage ring, disturbance of a beam line optical element movement mechanism and the like, and can effectively improve experimental efficiency and experimental data quality; the working intensity of operators is reduced; the remote control is convenient for the user, and the scientific research capability of the user is improved.
In order to achieve the above object, the present invention provides an automatic feedback dimming system of a beam line station, which is characterized by comprising a local area network, and a beam line system, an outgoing slit system, an experiment station, a system parameter module and an automatic feedback control module which are connected with the local area network;
The light beam line system, the emergent slit system and the experiment station are sequentially arranged, the emergent slit system is used as a dimming optical element and comprises four knife edges, the experiment station is provided with a light intensity detection system, and the light intensity detection system comprises a gold mesh and a photodiode which are arranged at the experiment station;
the system parameter module is configured to store main adjustment parameters and feedback parameters of the dimming optical element in a table look-up mode parameter file, wherein the main adjustment parameters of the dimming optical element comprise dimming parameters of a beam line system and dimming parameters of an emergent slit system, and the feedback parameters comprise photocurrent signals of four edges of the emergent slit system, a gold wire and luminous flux signals of a photodiode;
the automatic feedback control module is set to acquire control authority of main adjusting parameters of the dimming optical element, read authority of real-time feedback parameters and acquire authority of table lookup mode parameter files from the system parameter module, and obtain an influence rule of the change of the dimming parameters of the beam line system on the change of the feedback parameters according to the table lookup mode parameter files; reading photocurrent signals of four knife edges of the exit slit system in real time, and determining current deviation of the current center of the exit slit system relative to the opening center of the exit slit system in real time through the photocurrent signals of the four knife edges of the exit slit system; when the current deviation is larger than a set current deviation threshold, determining a correction offset of the dimming parameter of the beam line system according to the influence rule, and correcting the dimming parameter of the beam line system according to the correction offset, wherein the correction offset of the dimming parameter of the beam line system refers to the offset of the parameter when the photocurrent signal values of the left and right knife edges of the exit slit system are the same and the photocurrent signal values of the upper and lower knife edges are the same.
The light beam system comprises a light source, a plane mirror, a monochromator grating and a focusing mirror which are sequentially arranged and used as light modulation optical elements, and the light modulation parameters of the light beam system comprise incident light energy value E of the light source, xyz three-dimensional coordinates of the plane mirror and the focusing mirror and angles in meridian and sagittal directions, and linear density of the monochromator grating, cff value, xyz three-dimensional coordinates and angles in meridian and sagittal directions; the dimming parameters of the exit slit system comprise the center coordinates of the opening and the size of the opening of the exit slit system.
The light source is an undulator, and the dimming parameter of the beam line system further comprises a Gap value and a Shift value of the undulator.
Each dimming optical element is configured with an encoder and a grating scale to obtain the primary tuning parameters of the dimming optical element.
The emergent slit device is provided with a photoelectric signal conversion device and a current-to-voltage conversion device, wherein the photoelectric signal conversion device is respectively and electrically connected with four knife edges of the four-knife slit, and the current-to-voltage conversion device is connected with the photoelectric signal conversion device.
The gold wire net is arranged at the front end of the experimental station, the photodiode is arranged at a position near the rear end of the sample in the experimental station, and a pinhole diaphragm arranged at the front end of the gold wire net is arranged in the experimental station.
In another aspect, the present invention provides an automatic feedback dimming method for a beam line station, including:
s1, an automatic feedback dimming system based on a beam line station is constructed, and the automatic feedback dimming system comprises a local area network, and a beam line system, an emergent slit system, an experiment station, a system parameter module and an automatic feedback control module which are connected with the local area network; the light beam line system, the emergent slit system and the experiment station are sequentially arranged, the emergent slit system is used as a dimming optical element and comprises four knife edges, the experiment station is provided with a light intensity detection system, and the light intensity detection system comprises a gold mesh and a photodiode which are arranged at the experiment station;
s2, acquiring control authority of main adjustment parameters of the dimming optical elements through a local area network by utilizing an automatic feedback control module, reading real-time feedback parameters and acquiring authority of a table look-up mode parameter file from a system parameter module, and obtaining influence rules of changes of the main adjustment parameters of different dimming optical elements on changes of the feedback parameters according to the table look-up mode parameter file;
the main adjusting parameters of the dimming optical element comprise a dimming parameter of a beam line system and a dimming parameter of an emergent slit system, and the feedback parameters comprise photocurrent signals of four edges of the emergent slit system, a gold mesh and luminous flux signals of a photodiode;
S3, under the condition that the opening size of the emergent slit system is enlarged, attempting to call a lookup table mode parameter file in a corresponding range according to the current experimental condition, and if the call is successful, using the dimming parameter of the beam line system in the lookup table mode parameter file as an initial correction offset of a main adjusting parameter of the dimming optical element, and correcting the dimming optical element of the beam line system; otherwise, manually adjusting the dimming optical element of the beam line system, and storing the manual adjustment result into a table look-up mode parameter file in the form of a parameter list by using the system parameter module as an optimal parameter of the dimming parameter of the beam line system;
s4, measuring signals of the photodiodes while scanning by integrally moving the emergent slit system, and calibrating the position of the opening center of the emergent slit system;
s5, utilizing an automatic feedback control module to read photocurrent signals of four knife edges of the emergent slit system in real time, and determining current deviation of the current center of gravity of the emergent slit system relative to the opening center of the emergent slit system; when the current deviation is larger than a set current deviation threshold value, determining a correction offset of the dimming parameter of the beam line system according to the influence rule of the change of the dimming parameter of the beam line system on the change of the feedback parameter, correcting the dimming parameter of the beam line system according to the correction offset, wherein the correction offset of the dimming parameter of the beam line system refers to the offset of the parameter when the photocurrent signal values of the left and right knife edges of the outgoing slit system are the same and the photocurrent signal values of the upper and lower knife edges are the same, otherwise, not correcting;
S6, after finishing correction according to the correction offset, the main adjusting parameters and the feedback parameters of the dimming optical element are timely stored in a table look-up mode parameter file by utilizing a system parameter module; and then, an automatic feedback control module is utilized, and the influence rule of the change of the dimming parameter according to the beam line system on the change of the feedback parameter is obtained through machine learning updating according to the table look-up mode parameter file.
The step S3 specifically includes:
s31, setting an incident light energy value of a light source as a current experimental condition, and amplifying the opening size of an emergent slit system; utilizing an automatic feedback control module to attempt to retrieve a table look-up mode parameter file in a corresponding range of the incident light energy value of the current light source in the system parameter module;
s32, judging whether a stored lookup table mode parameter file in a corresponding range exists, if so, attempting to call successfully, and if not, executing a step S33, otherwise, executing a step S34;
s33, a table look-up mode parameter file of the latest date is called, the optimal parameter of the dimming parameter of the beam line system in the table look-up mode parameter file is used as the initial correction offset of the main adjusting parameter of the dimming optical element, and the dimming optical element is corrected by reading the initial correction offset through the dimming optical element;
If the absolute value of the difference between the set incident light energy value and the called incident light energy value of the lookup table mode parameter file is smaller than 5eV, directly performing step S4; otherwise, after the initial correction offset is read in by the dimming optical element to correct the dimming optical element, step S34 is performed;
and S34, manually adjusting the dimming parameters of the beam line system in the main adjusting parameters of the dimming optical element according to the feedback parameters in the system parameter module, taking the manual adjusting result as the optimal parameters of the dimming parameters of the beam line system, manufacturing a corresponding table look-up mode parameter file in a parameter list form, and then executing step S4.
When the manual adjustment standard is adopted in the step S4, the step S4 includes:
s41, setting an automatic feedback control module to be in a manual mode, calibrating coordinates by taking a focusing optical element in an experimental station as a center, and setting a light path center; opening sizes of four knife edges of the emergent slit system are enlarged, detection is carried out by adopting a photodiode, and the change of luminous flux signal values of the photodiode is observed while the dimming parameter is regulated; then, recording and storing the dimming parameters of the corresponding beam line system when the luminous flux signal value of the photodiode is maximum as optimal parameters in a form of a parameter list to a corresponding table look-up mode parameter file;
S42, gradually reducing the opening size of the emergent slit system, adjusting the position of the opening center of the emergent slit system, observing the change of the signal of the photodiode, and selecting the position of the opening center of the emergent slit system corresponding to the highest luminous flux to be calibrated as the calibrated opening center;
s43, designating the opening size of the emergent slit system, under the designated opening size, taking the designated opening center as an origin, integrally moving the emergent slit system in the direction vertical to the light beam for scanning, and simultaneously recording and obtaining the luminous flux signal values of the photodiodes when the opening centers are at different scanning positions, and automatically positioning the optimal positions of the opening centers according to the luminous flux signal values of the photodiodes;
then, the optimal position of the opening center of the emergent slit system corresponding to different opening sizes and the luminous flux signal value of the photodiode are used as optimal parameters and stored in a table look-up mode parameter file of corresponding incident light energy values in a parameter list mode;
when the system parameter module has saved the current optimal parameters of the dimming parameters of the beam line system and the dimming parameters of the exit slit system under the incident light energy value, the step S4 adopts automatic adjustment calibration, and the step S4 includes:
S41', determining whether the gold mesh is inserted into the optical path during an experiment according to the experiment requirement; if the gold wire is inserted into the light path during the experiment, the luminous flux signal value of the photodiode is used as the luminous flux signal value recorded in the step S42', otherwise, the luminous flux signal value of the gold wire is used as the luminous flux signal value recorded in the step S42';
s42', automatically introducing the optimal parameter under the current incident light energy value by the automatic feedback control module, and under the condition that the dimming parameter of the beam line system is regulated to the optimal parameter and kept motionless, taking the optimal parameter of the dimming parameter of the emergent slit system as an origin, integrally moving in the direction perpendicular to the beam to perform automatic scanning, and recording to obtain luminous flux signal values of the opening center at different scanning positions while scanning, finding the optimal position of the corresponding opening center when the luminous flux signal value is maximum, and driving the opening center of the emergent slit system to the optimal position; and storing the main adjusting parameters of the dimming optical element when the luminous flux signal value is maximum as optimal parameters into a table look-up mode parameter file.
The current deviation of the current center of gravity of the exit slit system relative to the opening center of the exit slit system comprises a left-right current deviation and an up-down current deviation, wherein the left-right current deviation S RL And up-down current deviation S UD The method comprises the following steps:
S RL = (S R -S L ) / (S R +S L )，
S UD = (S U -S D ) / (S U +S D )，
wherein S is R Is a photocurrent signal of a right knife edge, S L Is a photocurrent signal of a left knife edge, S U Is a photocurrent signal of an upper knife edge, S D Is a photocurrent signal of the lower knife edge.
According to the automatic feedback dimming device system for the beam line station, when the energy is replaced, the elements are switched, the beam group of the storage ring is fluctuated, the center of a light spot is greatly dithered due to disturbance of a moving mechanism of the beam line optical element and the like, the four-knife current signal of the emergent slit is monitored in real time, the current deviation of the four knife edges of the emergent slit is determined, the offset direction and the offset of the center position of the light beam in the experiment are easy to judge, the posture of the beam line optical element is automatically fed back and corrected, the central light spot is always irradiated to a sample by correcting the posture of the upstream optical element, the light spot flux and the position on the surface of the sample are kept constant, and therefore the experimental efficiency and the experimental data quality are improved.
In addition, for long-time running experiments, the invention adopts the automatic feedback control module to carry out automatic feedback, so that the offset of the beam center is monitored and corrected in real time, and compared with manual adjustment by operators, the automatic adjustment is free from staring at a running state at any time, is convenient for users to remotely operate and control, and greatly reduces the labor intensity of workers. The high-frequency automatic feedback adjustment improves the efficiency of the experiment, and simultaneously ensures the experiment persistence and the data quality.
Furthermore, the upstream beam line is provided with a plurality of dimming elements, and the beam center offset is the result of the influence of a plurality of factor variables.
In summary, the invention integrates the adjustment parameters and the feedback parameters of the beam line system into the automatic control program module, can realize real-time monitoring and correction of luminous flux change during experiments, and simultaneously maintains the constant central position of the optical path, thereby realizing long-time operation of the experiments under the optimal experimental conditions, greatly improving the experimental efficiency, facilitating remote operation control of users and greatly reducing the labor intensity of experimental operation. The invention has important significance for improving the efficiency and experimental quality of the beam line station experiment, has guidance for the construction of other line stations with similar devices, and provides technical support for the construction of new light sources and similar line stations.
Drawings
Fig. 1 is a schematic diagram of the signal connection relationship of the automatic feedback dimming system of the beam line station of the present invention.
Fig. 2 is a schematic mechanical structure of an automatic feedback dimming system of the beam line station of the present invention.
Fig. 3 is an overall flowchart of an automatic feedback dimming method of the beam-line station of the present invention.
Fig. 4 is a flowchart illustrating the specific operation of steps S3-S5 of the automatic feedback dimming method of the beam-line station of the present invention.
Description of the embodiments
Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Fig. 1 and 2 show an automatic feedback dimming system of a beam line station according to an embodiment of the present invention, which is based on an existing experimental system and needs to add a hardware module or a method step to implement the system. All the automatic feedback dimming device systems are operated independently of the experimental station, and the priority of the control authority of the beam line dimming equipment is lower than that of the experimental station.
The existing experiment system comprises a beam line system 10, an emergent slit system 20 and an experiment station 30 which are sequentially arranged, and a light intensity detection system 31 is arranged at the experiment station 30.
Wherein the beam line system 10 is configured to provide incident light 100 of different energy and characteristics to an experimental station 30 downstream thereof, in this embodiment, the beam line system 10 includes a light source (e.g., an undulator, a bent iron or a wiggler device), a flat mirror 11, a monochromator grating 12, and a focusing mirror 13, which are sequentially disposed, wherein the undulator light source, the flat mirror 11, the monochromator grating 12, and the focusing mirror 13 are all dimming optical elements.
The experiment station 30 is a platform for performing experiments on samples, the center of which is provided with the samples, and the center of the samples is a coordinate reference point for collimation of the light path of the whole beam line. Taking the experiment station 30 as an example of a high-resolution imaging platform, the experiment station 30 comprises a vacuum cavity, a light spot focusing element (a zone plate, a graded diaphragm, a capillary tube and the like), a plurality of motor movement sliding tables, and the motor movement sliding tables comprise a high-precision sample displacement table with four dimensions or higher dimensions, a detector displacement table with a plurality of different functions and the like. The light spot focusing element focuses the light spot after the slit to a proper size again according to the light spot size required by sample imaging. In order to achieve high precision and fast collimation of the optical path during the experiment, the spot focusing element of the experimental station 30 is typically required to be stationary, which requires that the center of the optical path is stationary and that the flux can be maintained in an optimal region when the pose of the incident light is changed during the experiment.
The light intensity detection system 31 is arranged to measure the light flux signal downstream of the exit slit system 20 in real time or in advance of the light path alignment, preferably at the sample to be measured. In order to facilitate the adjustment of the opening size, in this embodiment, the light intensity detection system 31 includes a gold mesh 311 and a photodiode 312 provided at the experiment station 30. Wherein the gold mesh 311 is removably disposed at the front end of the experiment station 30, and is configured to detect light intensity information in front of the experiment station 30 behind the exit slit system 20. In order to achieve on-line measurement of the luminous flux during the experiment without affecting the luminous flux at the downstream sample, the gold mesh 311 is a mesh structure of a certain mesh (e.g. 200 mesh, 300 mesh, 400 mu) so as to have a certain transmittance, and the sample and the photodiode 312 are not required to be moved out of the optical path for on-line use during the experiment, but this may not be accurate enough for measurement of small-sized light spots (tens of microns). Thus, the photodiode 312 is configured on the detector displacement stage of the laboratory station 30 for accurate measurement. A photodiode 312 is provided at a position inside the experimental station 30 near the rear end of the sample, which is configured to be switchable by a motor, and measures light intensity information at the sample inside the experimental station 30 when switching onto the optical path. While photodiode 312 is in the optical path, the sample is required to move out of the optical path.
That is, if the experiment requires real-time on-line monitoring of the light flux impinging on the sample, the gold mesh 311 is moved into the light path; if the light flux impinging on the sample is measured more accurately, it is moved into the optical path of the photodiode 312, but the photodiode 312 can only calibrate the light flux before the experiment.
During beam line installation, offline light path collimation has been performed by laser calibration. For the on-line case of X-ray incidence, it is necessary to monitor the luminous flux signals at specific locations such as monochromatic light exit slits, pre-laboratory and sample sites for optical path collimation. For light intensity detection systems, some of which are already in construction for beam line stations, such as gold nets and photodiode detectors, both of which read the light signal by a picometer.
Furthermore, between the exit slit system 20 and the downstream experimental station 30, light blocking elements such as shutters, diaphragms (e.g. pinhole diaphragms), shutters, etc. (not shown) may be provided for dimming. In the invention, in order to ensure that the central position of the optical path is constant, the smallest light spot at the sample can reach hundred micrometers, so that a pinhole diaphragm with a proper size is also required to be configured in the experiment station 30 for higher-precision positioning. Pinhole diaphragms are small holes of a certain size, e.g. 50um, for selecting the size of the transmitted light spot. Before the pinhole diaphragm is placed between the sample and the gold mesh 311, the gold mesh 311 is placed between the pinhole diaphragm and the sample, and for micrometer-sized samples, the size is too small, and since the exit slit system 20 is at a distance from the sample, the opening size of the exit slit system 20 is typically tens of micrometers, and in order to more accurately achieve positioning of the center of the light spot to the micrometer-sized sample, a pinhole diaphragm is used.
For beam lines with monochromators, the light incident on the laboratory station 30 is in a fan-shaped distribution, and in order to select a certain bandwidth of high energy resolution incident light, an exit slit system 20 is required. The exit slit system 20 also acts as a dimming optical element arranged to adjust the energy resolution and spatial coherence of the incident light according to the requirements of the experimental station 30. In this embodiment, as shown in fig. 2, the exit slit system 20 generally selects a four-blade slit, where the four-blade slit includes two pairs of blades that move relatively, namely, a left blade 21 of the four-blade slit, a right blade 22 of the four-blade slit, an upper blade 23 of the four-blade slit, and a lower blade 24 of the four-blade slit, and the four blades of the four-blade slit are independent of each other and are not in communication with each other. The opening size of the four-knife slit is usually only tens of micrometers, and the opening size and the position of the opening center can be electrically adjusted, so that the monochromaticity and the spatial coherence of emergent light can be conveniently adjusted.
The beam line layout of a synchrotron radiation light source is typically several tens of meters long, and a slight disturbance or error in the optical elements of the upstream beam line can cause the central spot at the exit slit system 20 to deviate from the center of the opening of the four-knife slit, resulting in a sharp drop in the light intensity at the downstream experiment station 30. In view of the small slit opening, the area of the light spot incident on different knife edges directly determines the signal size of the knife edge, if the light signal values of four knife edges are led out, the deviation direction and the deviation amount of the center of the light spot can be judged through relative change, and the position correction of the center light spot can be realized through the posture correction of each optical dimming element. Therefore, the outgoing slit device 20 of the present invention is provided with a photoelectric signal conversion device electrically connected to the four edges of the four-blade slit and a current-to-voltage conversion device electrically connected to the photoelectric signal conversion device, and the photoelectric signal conversion device is electrically connected to the four edges of the four-blade slit through wires. The photoelectric signal conversion device is used for converting optical signals irradiated on four knife edges of the four-knife slit into current signals for detection and reading, and the current-to-voltage conversion device is used for converting the photocurrent signals of the four knife edges into voltage forms so as to realize remote data transmission. Whereas beam-line stations each cover a certain energy range, different energies have different luminous fluxes, and the fluxes corresponding to low and high energies may even differ by an order of magnitude. Therefore, the current-to-voltage device needs to have an automatic adjustable range display function to improve the signal-to-noise ratio of the read signal, and the reading is enlarged by automatically jumping to a small range.
The electronic part of the current-to-voltage device needs to have a certain data acquisition frequency and a data reading frequency, such as a data acquisition frequency of 1MHz and a data reading frequency of 1kHz, so that the posture of the optical element can be conveniently adjusted by quickly feeding back and correcting the change of signal values on four knife edges. The difference between the two frequencies requires electronics to have an averaging process on the high frequency acquired data to increase the signal ratio. The acquisition frequency can be higher GHz, but the cost is high, but the high requirement is not needed in practice; the data read-out frequency needs to be referred to the correction time of the parameters of the light modulating element, and thus is not required to be too high.
Because the light spot incident to the slit of the four blades is larger than the slit opening, the four blades are mutually independent and are not communicated with each other, and the incident light irradiates the blades to cause external electron reflux due to the photoelectric effect of the optical signal conversion device, so that weak current of a nanoampere level is formed. The magnitude of the photocurrent signals of the four knife edges is related to the area of the light spot incident on the knife edges, so that the current on one side is large on a pair of knife edges in the horizontal direction or the vertical direction, which indicates that the incident light area on the side is larger than that on the other side, and the light is deviated in the direction of the pair of knife edges.
Referring to fig. 1 again, the automatic feedback dimming system of the beam line station of the present invention includes a local area network 40 for connecting the beam line system 10, the exit slit system 20, and the light intensity detection system 31, in addition to the existing experimental system. Specifically, the lan 40 has connected to it the dimming optics of the beam line system 10, including the focusing mirror 13, the monochromator grating 12, the plane mirror 11, etc., and adjusting the posture of the dimming optics changes the center of the downstream spot; the local area network 40 is connected with a current-to-voltage device of the emergent slit, so that current signals of four edges of the four-edge slit are read at a certain acquisition frequency, and specifically, the current-to-voltage device is provided with a network address so as to be conveniently connected into the local area network 40; the local area network 40 is connected to the light intensity detection system 31 so as to read the light flux signal value at the sample at a certain acquisition frequency.
The automatic feedback dimming system of the beam line station of the present invention further comprises a system parameter module 50 configured to store all parameters involved in the automatic feedback dimming system of the present invention in a look-up table mode parameter file, which may result from slowly saving the accumulated parameter file by a large number of manual adjustments to the beam line. The parameters stored in the system parameter module 50 specifically include: 1) A primary tuning parameter of a dimming optical element, which primarily relates to an optical element having a large influence on the beam tuning, comprising: a) Dimming parameters of the beam line system 10, including the incident light energy value E of the light source and the Gap and Shift values of the undulator; the xyz three-dimensional coordinates of the plane mirror 11 and the focusing mirror 13 and the angles of the meridian and sagittal directions; the linear density of the monochromator grating 12, cff value (fixed focusing constant), xyz three-dimensional coordinates and the angle in meridian and sagittal directions; b) Dimming parameters of the exit slit system 20, including the opening center coordinates and the opening size of the exit slit system 20; 2) Feedback parameters, including: a) Photocurrent signals of four knife edges of the exit slit system 20; and b) the luminous flux signal of the light intensity detection system 31 at the laboratory station, which comprises the signals of the gold grid 311 and the photodiode 312. In some embodiments, the parameters saved by the system parameters module 50 may further include: the response time of the shutter to the opening and closing of the light beam is also the main tuning parameter of the dimming optical element.
It should be noted that, the list of the dimming parameters of the exit slit system 20 in the system parameter module 50 and the list of the dimming parameters of the beam line system 10 do not necessarily correspond to each other, and in some embodiments, the same one a) dimming parameters of the beam line system 10 may correspond to a plurality of b) dimming parameters of the exit slit system 20.
In this embodiment, the light source is an undulator, and the incident light energy value E of the light source can be changed by the Gap value and the Shift value of the undulator, so the dimming parameter of the beam line system 10 includes the Gap value and the Shift value of the undulator, the Gap value is the distance between the magnets, and the Shift value is the value of the pair of magnets that are staggered with each other. The undulator can select the energy, flux and polarization of the beam line by changing the Gap value and Shift value (Gap value is the distance between magnets, shift value is the value that a pair of magnets are staggered from each other) of the undulator, thereby selecting the proper incident light. In other embodiments, where the light source is not an undulator, the dimming parameters of the beam line system 10 do not include the Gap value and Shift value of the undulator.
The automatic feedback control module 60 is configured to obtain the control authority of the main adjustment parameters of the dimming optical element through the local area network 40, read the real-time feedback parameters, and retrieve the read authority of the table look-up mode parameter file from the system parameter module, and obtain the rule of influence of the change of the dimming parameters of the beam line system 10 (especially the photocurrent signals of the four knife edges) on the change of the feedback parameters according to the main adjustment parameters of the different dimming optical elements according to the table look-up mode parameter file. The automatic feedback control module 60 is further configured to read the photocurrent signals of the four edges of the exit slit system 20 (and may further read the luminous flux signals of the light intensity detection system 31 at the experimental station) in real time, determine, in real time, a current deviation of the current center of gravity of the exit slit system 20 with respect to the opening center of the exit slit system 20 by the photocurrent signals of the four edges of the exit slit system 20, and determine, when the current deviation is greater than a set current deviation threshold, a correction offset of the dimming parameter of the beam line system 10 among the main adjustment parameters of the dimming optical element according to the above-mentioned influence rule, and correct the dimming parameter of the beam line system 10 according to the correction offset. The correction offset of the dimming parameter of the beam line system 10 in the main adjustment parameters of the dimming optical element refers to an offset of parameters when the photocurrent signal values of the left and right edges of the exit slit system 20 are the same and the photocurrent signal values of the upper and lower edges are the same. Thereby, automatic collimation of the light path at the downstream experimental station and maintenance of constant maximum luminous flux are achieved through automatic feedback.
In this embodiment, the system parameter module 50 and the automatic feedback control module 60 are installed on a control computer, and are connected to the other beam line system 10, the exit slit system 20, and the light intensity detection system 31 through the lan 40. The automatic feedback control module 60 should have remotely controllable authority, which facilitates remote offline control by the laboratory operator.
If the beam-line station is in a line-multi-station configuration, multiple automatic feedback control modules 60 are required for automatic adjustment of the multiple beam-line stations, each automatic feedback control module 60 requiring a different system parameter module 50 to be matched.
Since each beam-line station design covers a range of energies, it is not possible to refine the experimentally-induced light energy values stored in the system parameter module 50, and thus the automatic control program 60 needs to have the function of interpolating the parameters of the closest-in light energy values read from the system parameter module 50.
In this embodiment, the automatic feedback control module 60 accesses the control software of the beam line system and the exit slit system to obtain the control authority of the main adjustment parameters of the dimming optical element, and makes the matching and connection problem of different control software, and the priority of the control authority, and meanwhile, needs to consider the timely feedback speed during data control.
The dimming optics include the light source of the beam line system 10, the flat mirror 11, the focusing mirror 13 and the monochromator grating 12, and the individual knife edges of the exit slit system 20.
It should be noted that, the main adjustment parameters of the dimming optical element first need to be manually adjusted and optimized to the optimal pose in advance, and as described above, the main adjustment parameters of the dimming optical element include: a) Dimming parameters of the beam line system 10, including the incident light energy value E of the light source and the Gap and Shift values of the undulator; the xyz three-dimensional coordinates of the plane mirror 11 and the focusing mirror 13 and the angles of the meridian and sagittal directions; the linear density of the monochromator grating 12, cff value, xyz three-dimensional coordinates and the angle in meridian and sagittal directions; b) The dimming parameters of the exit slit system 20, which include the opening center coordinates and the opening dimensions of the exit slit system 20. Then, the table look-up pattern parameter file is gradually formed by a large number of main adjustment parameters and corresponding feedback parameters of the dimming optical element. The obtained table look-up mode parameter file comprises the influence rules of the change of the main adjusting parameters of different dimming optical elements on the change of the feedback parameters, wherein the main adjusting parameters of the different dimming optical elements specifically comprise the incident light energy value E of the light source, and the Gap value and the Shift value of the undulator; the xyz three-dimensional coordinates of the plane mirror 11 and the focusing mirror 13 and the angles of the meridian and sagittal directions; the linear density of the monochromator grating 12, cff value, xyz three-dimensional coordinates and the angle in meridian and sagittal directions; b) The dimming parameters of the exit slit system 20, which include the opening center coordinates and the opening dimensions of the exit slit system 20. Then, when the center of the light source deviates due to a plurality of influencing factors, the posture of the dimming device is unstable due to power supply factors, and the luminous flux of the experiment station 30 has obvious changes due to factors such as ground vibration, the influence rule of the changes of the main adjusting parameters of different dimming optical elements on the changes of the feedback parameters is obtained by automatically retrieving the table lookup mode parameter file, the main adjusting parameters of each dimming optical element corresponding to the luminous flux are automatically searched as correction offset through numerical calculation according to the influence rule of the changes of the main adjusting parameters of the different dimming optical elements on the changes of the feedback parameters, and the main adjusting parameters of the dimming optical elements are corrected according to the correction offset, so that the collimation of the light path and the maintenance of the constant flux posture are quickly realized. It should be noted that the efficient questionnaire mode parameter file for automatic feedback dimming requires that all dimming optical elements have high precision positioning that can be adjusted repeatedly, so each dimming optical element (including the plane mirror 11, the monochromator grating 12 and the focusing mirror, and the knife edge of the exit slit system 20) needs to be configured with high precision motion measuring devices such as encoders and grating scales to obtain the main adjustment parameters of the dimming optical element, and ensure the accuracy of the movement. Specifically, the grating ruler is fixed on the electric sliding table of each dimming optical element, the encoder irradiates the grating ruler through the emitted laser, and the accurate position of the motor is deduced according to the light reflected at the fixed position.
Thus, referring to the beam-line station layout shown in fig. 2 and the flowchart of automatic feedback dimming shown in fig. 3, the automatic feedback dimming method of the beam-line station implemented by the automatic feedback dimming system of the beam-line station includes the steps of:
step S1, constructing an automatic feedback dimming system based on a beam line station as shown in FIG. 1 and described above;
the automatic feedback dimming system based on the beam line station comprises a local area network 40, a beam line system 10, an emergent slit system 20, an experiment station 30, a system parameter module 50 and an automatic feedback control module 60, wherein the beam line system 10, the emergent slit system 20 and the experiment station 30 are connected with the local area network 40 and are sequentially arranged, the emergent slit system 20 is used as a dimming optical element and comprises four knife edges, and the experiment station 30 is provided with a light intensity detection system 31; the light source of the beam line system 10, the plane mirror 11, the focusing mirror 13 and the monochromator grating 12 and the respective edges of the exit slit system 20 are used as dimming optical elements.
Step S2, the automatic feedback control module 60 is utilized to acquire the control authority of the main adjusting parameters of the dimming optical elements through the local area network 40, read real-time feedback parameters and access and look-up table mode parameter files from the system parameter module 50, wherein the look-up table mode parameter files comprise the influence rules of the changes of the main adjusting parameters of different dimming optical elements on the changes of the feedback parameters;
The step S2 specifically includes: step S21, the local area network is connected to the beam line system 10 and the emergent slit system 20, and the control authority of main adjusting parameters of the dimming optical element is obtained through the local area network 40; step S22, connecting a current-to-voltage device of the exit slit system 20 through a local area network to obtain the authority of reading the photocurrent signals of the four edges of the exit slit system 20; in step S23, the lan is connected to the light intensity detection system 31 to obtain the authority to read the signal value.
The control authority of the primary tuning parameters of the optical element is used to modify the primary tuning parameters of the dimming optical element. A primary tuning parameter of a dimming optical element, which primarily relates to an optical element having a large influence on the beam tuning, comprising: a) Dimming parameters of the beam line system 10, including the incident light energy value E of the light source and the Gap and Shift values of the undulator; the xyz three-dimensional coordinates of the plane mirror 11 and the focusing mirror 13 and the angles of the meridian and sagittal directions; the linear density of the monochromator grating 12, cff value, xyz three-dimensional coordinates and the angle in meridian and sagittal directions; b) The dimming parameters of the exit slit system 20, which include the opening center coordinates and the opening dimensions of the exit slit system 20. In some embodiments, the response time of the shutter to the opening and closing of the light beam is also the primary tuning parameter of the dimming optics.
The feedback parameters in the system parameter module 50 include a) photocurrent signals of the four knife edges of the exit slit system 20; and b) a luminous flux signal at the laboratory station 30 comprising the signals of the gold grid 311 and the photodiode 312.
Step S3: under the condition that the opening size of the exit slit system 20 is enlarged, attempting to call a lookup table mode parameter file in a corresponding range according to the current experimental condition, and if the call is successful, using the dimming parameter of the beam line system 10 in the main adjusting parameters of the dimming optical element in the lookup table mode parameter file as an initial correction offset, and correcting the dimming optical element of the beam line system 10 under the condition that the opening size of the exit slit system 20 is enlarged; otherwise, the dimming optics of the beamline system 10 are manually adjusted, and the manual adjustment result is stored in the table look-up mode parameter file in the form of a parameter list as the optimal parameters for the dimming parameters and feedback parameters of the beamline system by using the system parameter module 50.
The manual adjustment results are used as optimal parameters for the dimming parameters of the beam line system 10 during the process of storing the table look-up mode parameter file. Generally, the manual adjustment result of step S3 is only a parameter set next time, not for machine learning later.
The step S3 specifically includes:
step S31, setting an incident light energy value E of the light source as the current experimental condition, and enlarging the opening size of the emergent slit system 20; the auto-feedback control module 60 is utilized to attempt to retrieve a table look-up pattern parameter file within a corresponding range of incident light energy values for the current light source in the system parameter module 50.
The corresponding range of the current light source incident light energy value is a table look-up mode parameter file within 680-720eV, if the current set incident light energy value E is 700 eV.
Considering that each beam line covers a certain energy range, only one suitable value E of the incident light energy can be selected in the energy range for optimization, and other energy can be adjusted in the energy range. For a beam line with energy of 250eV-2000eV, the device such as an upstream optical element and a downstream optical element is usually optimized by taking 700eV as the central energy in design. In practical experiments, 700eV light is strongest, but the light intensity is relatively weak regardless of the optimization of the optical element with low energy of 250eV or high energy of 2000 eV. In practical experiments, any energy value within an energy segment may be selected.
Step S32, if the attempt to call is successful, step S33 is performed, otherwise, step S34 is performed if the attempt to call is failed.
And judging whether a stored lookup table mode parameter file in a corresponding range exists, if so, attempting to call successfully, otherwise, attempting to call failed.
In step S33, when the attempt to retrieve is successful, the lookup table mode parameter file of the latest date is retrieved, and the optimal parameter of the dimming parameter of the beam line system 10 in the lookup table mode parameter file is used as the initial correction offset of the main adjustment parameter of the dimming optical element, and the dimming optical element is corrected by reading the initial correction offset through the dimming optical element.
Each set of data of the table look-up mode parameter file contains the energy + date + coordinate parameters of the dimming optics; in the case of a certain energy, it is usual to retrieve the parameter file closest to the set incident light energy value and the latest date.
In order to ensure the strongest luminous flux, the document is kept as close as possible to the set incident light energy value. Thus, step S33 further includes: if the absolute value of the difference between the set incident light energy value and the called incident light energy value of the lookup table mode parameter file is smaller than 5eV, the obtained dimming optical element is considered to read the initial correction offset accurately, and step S4 is directly performed at the moment; otherwise, it is considered that the initial correction offset amount read in by the dimming optical element is approximate, and therefore, after the dimming optical element is corrected by reading in the initial correction offset amount, step S34 is performed to achieve manual adjustment.
Step S34, manually adjusting the dimming parameters of the beam line system 10 in the main adjusting parameters of the dimming optical element according to the feedback parameters in the system parameter module 50, and making a corresponding table look-up mode parameter file in the form of a parameter list by using the manual adjusting result as the optimal parameter of the dimming parameters of the beam line system, and then executing step S4. Thereby, a manual adjustment of the optical path center is achieved.
In this embodiment, in the step S34, the manual adjustment is performed according to the signal of the gold 311 in the feedback parameter in the system parameter module 50.
Further, step S34 may include: the jump indicates that manual adjustment is required.
The step S34 specifically includes:
step S341, adjusting the Gap value and the Shift value of the undulator to obtain a light source with a set incident light energy value, then adjusting the rotation angle of the monochromator grating 12, adjusting the posture of the focusing mirror 13, and simultaneously observing the light flux signal at the sample measured by the gold grid 311 to adjust the light flux signal at the sample to the highest light flux;
therefore, through the coupling of the gesture of the light modulation element, the light intensity of the experimental station in the corresponding energy range has the highest luminous flux, and the highest luminous flux is judged by observing the signal value curve of the gold wire mesh 311 at the sample of the experimental station.
Step S342, the dimming parameters of the beam line system 10 and the signal values of the gold grid 311 in the main adjusting parameters of the dimming optical element corresponding to the highest luminous flux are stored in the table look-up mode parameter file in the form of a parameter list and saved;
as described above, the main tuning parameters of the dimming optical element include: a) Dimming parameters of the beam line system 10, including the incident light energy value E of the light source and the Gap and Shift values of the undulator; the xyz three-dimensional coordinates of the plane mirror 11 and the focusing mirror 13 and the angles of the meridian and sagittal directions; the linear density of the monochromator grating 12, cff value, xyz three-dimensional coordinates and the angle in meridian and sagittal directions; b) The dimming parameters of the exit slit system 20, which include the opening center coordinates and the opening dimensions of the exit slit system 20. These parameters may be measured by high precision motion measurement devices provided on each dimming optical element.
Therefore, the table look-up mode parameter file can store the optimal parameters and the highest luminous flux of the dimming parameters of the beam line system 10 with different energy values, and accordingly, the influence rule of the change of the dimming parameters of the corresponding beam line system 10 on the change of the feedback parameters can be obtained.
In addition, since the beam line monochromator has a plurality of monochromator gratings 12 (having different linear densities), the energy ranges corresponding to each grating overlap, but the energy resolution (i.e., monochromaticity) of the incident light produced is different. For distinction, the specific naming of the parameter list of the lookup mode parameter file in the newly-created or updated system parameter module 50 should at least include the selection of the monochromator grating 12 (in this embodiment, the naming of the lookup mode parameter file also includes the incident light energy value+gap+shift+grating posture parameter+focusing mirror posture parameter+movement time+date), which is convenient for the later recall by the automatic feedback control module 60.
In step S341, in order to avoid the jamming caused by the failure of the hardware device, a beam line adjustment time threshold is preset before adjusting the luminous flux signal at the sample to be measured to the highest luminous flux, and the failure of adjusting the luminous flux signal at the sample to be measured to the highest luminous flux within the beam line adjustment time threshold is alerted.
The beam line adjustment time threshold may be 5 minutes, and if the motor is not complete, possibly stuck or enters a dead cycle, the program may give an alert signal.
In step S4, the position of the center of the opening of the exit slit system 20 is calibrated by moving the exit slit system 20 as a whole to scan while measuring the luminous flux signal of the photodiode 312 at the sample.
Since the center point of the sample of the final experimental station is preferably fixed, all optical elements, diaphragm devices, slits and the like of the beam line station need to be collimated by the coordinates of the center point of the sample. Although the laser device is adopted to calibrate the center position of the exit slit opening with the center point of the sample after the construction of the beam line station is completed, the calibrated center position has no reference value due to various influencing factors in long-time operation overshoot. Considering the effects of individual device adjustment mechanism fluctuations and malfunctions, and the possible change of the coordinate position of the dimming optics by different operators. The position of the center of the opening of the exit slit system 20 is preferably calibrated before the automatic feedback dimming control procedure is initiated. The central position of the emergent slit is calibrated, so that the problem of light path collimation error between the central position of the emergent slit and the center of the sample is solved, the signal change of a light intensity detection system at the sample is required to be observed, the emergent slit is scanned, and the light path collimation is realized between the center of the emergent slit and the center of the sample when the light intensity is maximum.
Step S4 may be implemented by manually adjusting both the calibration and automatically adjusting the read parameter file.
When the manual adjustment standard is adopted in the step S4, the step S4 includes:
step S41, the automatic feedback control module 60 is set to a manual mode, coordinates are calibrated by taking a focusing optical element in the experiment station 30 as a center, and the center of an optical path is set; the size of the openings of the four knife edges of the exit slit system 20 is increased, and the detection is performed by adopting the photodiode 312 at the sample, and the change of the luminous flux signal value of the photodiode 312 is observed while the dimming parameter of the beam line system 10 is regulated. Wherein the dimming parameter of the beam line system 10, which corresponds to the main dimming parameter of the dimming optics when the signal value is maximum, can be used to achieve the optical path center collimation. Subsequently, the dimming parameters of the beam line system 10 corresponding to the maximum luminous flux signal value of the photodiode 312 are recorded as the optimal parameters in the form of a parameter list and saved to the corresponding table look-up mode parameter file.
It should be noted that, in step S34, the exit slit is stationary, and the center of the four-knife slit is used as a reference point to adjust the upstream optical element to realize the collimation of the light path. In step S4, the upstream light is stationary, and the signal at the downstream sample is taken as a reference point, so as to adjust the central position of the exit slit to move.
In this embodiment, a pinhole diaphragm of a fixed size inserted before the sample is set as the optical path center. If the light blocking element exists, the light blocking element in front of the experimental station needs to be moved away from the light path while the opening sizes of the four knife edges are enlarged; the light blocking element may be a diaphragm, shutter, or the like.
In step S42, as shown in fig. 2, the opening size of the exit slit system 20 is gradually reduced, and the position of the opening center of the exit slit system 20 is adjusted, and meanwhile, the change of the signal of the gold mesh 311 or the photodiode 312 is observed, and the position of the opening center of the exit slit system 20 corresponding to the highest luminous flux is selected to be calibrated as the calibrated opening center.
The signal of the gold 311 or photodiode 312 measures the luminous flux signal at or near the sample.
In the actual experimental process, the actual center position of the exit slit is shifted (several millimeters or even tens of millimeters) due to motor shake, faults and the like, so that the light passing through the center cannot be incident on the downstream sample (200 micrometer area). Therefore, the center position of the exit slit needs to be calibrated with the sample point, at which time the photodiode (pd) at the sample needs to be moved into the optical path. Since the photodiode is large in size (20 mm×20 mm), and the spot at the sample is only hundred microns, a small hole with a certain size needs to be inserted before pd to position the center of the sample; by moving the exit slit to scan in the plane perpendicular to the light path, the signal value corresponding to the photodiode is recorded, and the maximum signal value corresponds to the center of the exit slit.
Step S43, designating the opening size of the exit slit system 20, under the designated opening size, taking the designated opening center as the origin, moving the exit slit system 20 integrally in the direction perpendicular to the light beam for scanning, and recording the luminous flux signal value of the photodiode 312 when the opening center is at different scanning positions while scanning, and automatically positioning the optimal position of the opening center according to the luminous flux signal value of the photodiode 312; and then, the optimal position of the opening center of the exit slit system 20 corresponding to the different opening sizes and the luminous flux signal value of the photodiode 312 are used as optimal parameters and stored in a table look-up mode parameter file of the corresponding incident light energy value in the form of a parameter list.
Wherein the current center of gravity of the exit slit system 20 is relative to the exitThe current deviation of the opening center of the slit system 20 includes a left-right current deviation S and an up-down current deviation RL And up-down current deviation S UD The method comprises the following steps:
S RL = (S R -S L ) / (S R +S L )，
S UD = (S U -S D ) / (S U +S D )，
S R is a photocurrent signal of a right knife edge, S L Is a photocurrent signal of a left knife edge, S U Is a photocurrent signal of an upper knife edge, S D Is a photocurrent signal of the lower knife edge.
In step S43, specifically, as shown in fig. 2, since the light spots corresponding to different incident lights have different light intensity distributions at the slits of the four knives, whether the light spots incident on the four knives are circular light spots or square light spots needs to be considered, so that on the basis of obtaining the current center of gravity of the outgoing slit system 20, it is necessary to determine different current deviations (i.e., a left-right current deviation and a vertical current deviation) of the current center of gravity corresponding to different physical position deviations of the current center of the opening center and the signal values of the photodiode 312 respectively according to the scanning method, so as to achieve calibration, and the physical position deviation corresponding to the current deviation of the center of gravity position of the four-knife current can be calculated according to the position of the opening center, the photocurrent signals of the four-knife edge and the signal values of the photodiode 312. On the premise of mechanically ensuring the collimation of the central light path, the current center of the emergent slit system 20 is compared with the slit center, and then certain correction processing is carried out on signals in the horizontal direction and the vertical direction (namely, calibration is carried out through the photocurrent signal difference in the horizontal direction and the numerical direction). Considering that the slit has a certain opening, the opening center is the geometric center of the slit, the light spot center corresponds to the center of the photocurrent signal, and if the light spot center is not deviated, the values of the photocurrent signals of the upper, lower, left and right knife edges are the same, which indicates that the center of gravity of the photocurrent signal coincides with the opening center of the emergent slit system 20. Therefore, the position of the opening center obtained in step S43 coincides with the current center of gravity (i.e. the spot center) of the exit slit system 20, and the opening center calibrated in step S42 may be the correct spot center or may have a certain deviation; if the opening center calibrated in the step S42 is the correct light spot center, the position of the opening center found after the scanning in the step S43 is unchanged; if the calibrated opening center is deviated, the position of the opening center found after the scanning in the step S43 is updated according to the position of the opening center when the spot center measured in the step S43 is coincident with the opening center.
Thereby, an optical path alignment process of the exit slit system 20 and the focusing optical element of the experiment station is realized, and signal value changes of the exit slit system 20 and the focusing optical element under different position deviations are recorded.
The method for scanning by using the calibrated opening center as the origin integrally moves specifically comprises the following steps: the exit slit system 20 moves in a spiral or lattice pattern with the nominal opening center as the origin. The lattice point mode movement refers to movement of the lattice point mode by one line with the marked opening center as an origin; the spiral motion is to take the marked opening center as the origin to perform spiral scanning. And when the signal value is maximum, the geometric center of the slit, the center of the rear focusing optical element and the center of the sample realize light path collimation.
The signal value of the photodiode 312 is near the highest luminous flux, and the signal values of the left and right edges of the exit slit system 20 are as large as the signal values of the upper and lower edges, so that the position of the opening center of the exit slit system 20 at this time is the correct position of the opening center.
Since in step S33, when the attempt to retrieve is successful, if the absolute value of the difference between the set incident light energy value and the incident light energy value of the invoked lookup table mode parameter file is smaller than 5eV, it is considered that the initial correction offset is read by the dimming optical element accurately, and the position of the opening center of the exit slit system 20 is calibrated further through step S4, otherwise, step S34 is required to be executed to ensure that the light flux signal at the sample to be measured is adjusted to the highest light flux, so that when the position of the opening center of the exit slit system 20 is calibrated in step S4, the dimming parameter of the beam line system 10 in the main adjustment parameter of the dimming optical element is the parameter that makes the signal value of the gold network 311 maintain the maximum reading in the experimental station, and step S4 can ensure that the relative difference between the four-knife slit level and the vertical current signal is the minimum as much as possible on the premise that the signal value of the gold network 311 maintains the maximum reading. Therefore, the light intensity distribution of the central light spot has relatively stable constant intensity in a certain area, the arrangement of the step S33 and the step S4 ensures that the position of the opening center of the emergent slit system 20 is positioned in the relatively stable area in the light intensity distribution of the central light spot, so that the deviation of the center of the light path caused by the shake of the light beam line dimming equipment and the shake of the related equipment motion motor in the experimental process is avoided, and the larger tolerance to the shake is ensured.
In the step S43, the number of the opening sizes of the specified exit slit system 20 may be plural, so as to save a dimming parameter list of the exit slit system 20 corresponding to the plural opening sizes. Accordingly, for the system parameter module 50, the stored list of dimming parameters of the exit slit system 20 and the list of dimming parameters of the beam line system 10 do not necessarily correspond one to one, and in some embodiments, the same one a) dimming parameters of the beam line system 10 may correspond to a plurality of b) dimming parameters of the exit slit system 20. This is because the distribution of the light spot at the four-knife slit is constant and the size is not changed in consideration of the incident light of a specific incident light energy value required for the experiment; however, in order to meet the requirement of selecting incident light with different energy resolutions in the experiment, the opening size of the four-knife slit needs to be adjusted at any time under the condition of the same incident light energy value (i.e. the dimming parameter of one beam line system 10 corresponds to the dimming parameters of a plurality of exit slit systems 20). The size of the opening is different in the selected central light spot area, so that the relative difference value of the four-knife current signal reading may change, and therefore, the relative difference value of signal values corresponding to a plurality of commonly used opening sizes needs to be recorded in a parameter file, so that the signal values can be conveniently retrieved and corrected at any time in the experiment.
When the system parameter module 50 has stored the current optimal parameters of the dimming parameters of the beam line system and the dimming parameters of the exit slit system under the incident light energy value, the step S4 can use automatic adjustment calibration; when the step S4 employs the automatic adjustment criterion, the step S4 includes:
step S41', determining whether the gold mesh in the experiment station 30 is inserted into the optical path during the experiment according to the experiment requirement; if the gold is inserted into the optical path at the time of the experiment, the luminous flux signal value of the photodiode 312 is used as the luminous flux signal value recorded in the step S42', otherwise, the luminous flux signal value of the gold 311 is used as the luminous flux signal value recorded in the step S42'.
For imaging experiments in general, gold meshes typically need to be moved out of the optical path, taking into account that the luminous flux is critical to the signal to noise ratio of the imaging. For absorption spectrum experiments, a gold mesh is generally required to realize real-time synchronous detection of incident light flux, so the gold mesh needs to be moved into an optical path.
In step S42', the automatic feedback control module 60 automatically imports the optimal parameter under the current incident light energy value, and under the condition that the dimming parameter of the beam line system 10 in the main adjusting parameter of the dimming optical element is adjusted to the optimal parameter and kept still, the opening center of the exit slit system 20 integrally moves in the direction perpendicular to the beam with the optimal parameter of the dimming parameter of the exit slit system as the origin to perform automatic scanning, records the light flux signal values of the photodiode 312 when the opening center is at different scanning positions while scanning, finds the optimal position of the corresponding opening center when the light flux signal value is maximum, and drives the opening center of the exit slit system 20 to the optimal position; and storing the main adjusting parameters of all the dimming optical elements as optimal parameters into a table look-up mode parameter file when the luminous flux signal value is maximum.
The current optimal parameter under the incident light energy value refers to the value of the main adjusting parameter of the corresponding adjusting optical element when the photocurrent signal values of the left and right edges of the exit slit system 20 are the same and the photocurrent signal values of the upper and lower edges are the same under the highest light flux. Since the system parameter module 50 has maintained a list of all parameters at the current incident light energy value, the parameter types of the optimal parameters include all parameter types at the same time. Thus, by the automatic scanning in which the opening center of the exit slit system 20 is moved integrally in the direction perpendicular to the light beam, it is achieved to verify whether the luminous flux and the spot center position reach the optimal experimental pose, i.e., to verify whether the optimal parameters are indeed optimal.
Step S5, the automatic feedback control module 60 is utilized to read photocurrent signals of four knife edges of the emergent slit system 20 in real time, and the current deviation of the current center of gravity of the emergent slit system 20 relative to the opening center of the emergent slit system 20 is determined; the automatic feedback correction is performed on the dimming parameter of the beam line system 10 in the main adjustment parameters of the adjusting optical element according to the current deviation, specifically, when the current deviation is greater than the set current deviation threshold, the correction offset of the dimming parameter of the beam line system is determined according to the influence rule of the change of the dimming parameter of the beam line system 10 on the change of the feedback parameter, the dimming parameter of the beam line system is corrected according to the correction offset, the correction offset of the dimming parameter of the beam line system refers to the offset of the parameter when the photocurrent signal values of the left and right knife edges of the exit slit system are the same and the photocurrent signal values of the upper and lower knife edges are the same, otherwise, the correction is not performed. Therefore, the beam center is kept constant, and the highest luminous flux at the sample in the experimental station is ensured.
Since there are multiple dimming elements upstream of the beam line that affect the center of the downstream beam, the automatic feedback control module 60 has multiple logic criteria built in.
Wherein the current deviation of the current center of gravity of the exit slit system 20 with respect to the opening center of the exit slit system 20 includes a left-right current deviation and an up-down current deviation, wherein the left-right current deviation S RL And up-down current deviation S UD The method comprises the following steps:
S RL = (S R -S L ) / (S R +S L )，
S UD = (S U -S D ) / (S U +S D )，
S R is a photocurrent signal of a right knife edge, S L Is a photocurrent signal of a left knife edge, S U Is a photocurrent signal of an upper knife edge, S D Photocurrent for lower knife edgeA signal.
Left-right current deviation S RL And up-down current deviation S UD The intensity of the beam center offset can be quantitatively expressed. Assuming that the light beam is deflected left and right in the horizontal direction with respect to the exit slit system 20, a significant increase in the difference in photocurrent signals of the left and right knife edges occurs. If S RL If yes, the beam is indicated to move towards the right edge; if S UD Negative numbers indicate that the beam is moving in the direction of the left edge. The difference S takes into account the movement accuracy and the error of the motor controlled by the upstream dimming element RL Is not zero, but is seen as a knife edge that does not move when small. Thus, a current deviation threshold Sv is set, for example, 5%, if the current deviation S is about RL Absolute value of (2)>The current deviation threshold value Sv is automatically fed back and started, the automatic feedback control module 60 determines the correction offset of the dimming parameter of the beam line system 10 in the main adjustment parameters according to the rule of influence of the change of the dimming parameter of the beam line system 10 on the change of the feedback parameter, and corrects the dimming parameter of the beam line system 10 according to the correction offset to realize the correction of the beam center; otherwise, the automatic feedback is not started. Similarly, if the beam is shifted in the vertical direction, the judgment logic is similar to that described above, if the up-down current is deviated S UD Absolute value of (2)>The current deviation threshold value Sv is automatically fed back and started, and the automatic feedback control module 60 determines the correction offset of the dimming parameter of the beam line system 10 in the main adjustment parameters according to the rule of influence of the change of the dimming parameter of the beam line system 10 in the main adjustment parameters of different dimming optical elements on the change of the feedback parameter, and corrects the dimming parameter of the beam line system 10 according to the correction offset to realize the correction of the beam center; otherwise, the automatic feedback is not started.
The correction offset of the dimming parameter of the beam line system 10 in the main adjustment parameters of the dimming optical element refers to an offset of parameters when the photocurrent signal values of the left and right edges of the exit slit system 20 are the same and the photocurrent signal values of the upper and lower edges are the same.
If the beam is shifted in an oblique direction, two logical judgment criteria need to be coupled,i.e. left-right current deviation S RL And up-down current deviation S UD Absolute value of the sum of the displacements of (2)>The current deviation threshold value Sv is automatically fed back for starting, otherwise, the automatic feedback is not started.
In addition, in step S5, other judgment logic may be set, for example, the sum of the photocurrent signals of the four knife edges of the exit slit system 20 needs to be greater than a certain value to judge the current deviation, which is to avoid that the four knife edges all have certain background noise signals when light is stopped, but the judgment logic of the relative difference value and the threshold value is not applicable and is not significant.
The step S5 further includes: the signal value of the gold wire is monitored in real time to monitor the luminous flux change in real time, and the dimming parameter of the beam line system 10 is regulated according to the signal value of the gold wire in real time to correct the central light spot incident on the emergent slit to realize the automatic collimation of the light path; the dimming parameters of the beam line system 10 include, among other things, the pose of the most downstream focusing mirror of the beam line (including xyz three-dimensional coordinates and meridional and sagittal angles), and if the latter intensity differences are large, the parameters related to the grating need to be adjusted.
In the actual working process, the four-knife current signal of the detection emergent slit and the gold mesh signal behind the detection slit are fed back automatically and synchronously. Generally, if the central position of the exit slit is calibrated, when the gold mesh signal is maximum, the deviation of the four-knife current of the exit slit in the horizontal direction and the vertical direction is also minimum respectively.
In addition, the manual mode can also aim at the fact that the deviation of the electron orbit of the accelerator is large, so that the light flux detected by the light flux detection system deviates by a plurality of orders of magnitude from the stored optimal parameter, and the highest light flux can not be found for a long time when the system calls in the stored historical parameter. At this time, the manual mode is required to be switched, the manual searching is performed according to the experience of the operator of the beam line station, and the optimal position is searched by switching to the automatic mode after the manual searching is mainly determined. Therefore, when the signal value of the currently monitored gold deviates by several orders of magnitude from the signal value of the optimal gold, the process returns to step S3 to switch back to the manual mode, and the manual search is performed according to the experience of the operator of the beam line station.
When the automatic control program corrects the postures of the plurality of dimming optical elements of the beam line system 10 by monitoring the photocurrent signals of the four knife edges, due to too many variables, the influence rule of the dimming parameters of the beam line system 10 in the main adjusting parameters of the dimming optical elements on the photocurrent signals of the four knife edges after coupling is difficult to judge. Therefore, the influence law can be obtained through a table look-up mode parameter file of the system parameter module 50 and machine learning, wherein the machine learning is to calculate the influence law of the dimming parameters of the beam line system 10 in the main adjustment parameters of each optical element on the photocurrent signals of the four knife edges according to a large number of simulations to find the optimal parameter combination, so as to correct the gesture of each optical element.
The machine learning data is that according to the design, layout and motion characteristics of the beam line dimming element, the influence rule of the dimming element on the downstream beam center is obtained through theoretical calculation and analysis. And then correcting the posture of the dimming element corresponding to the light path collimation in actual experiments to eliminate theoretical and actual deviation.
Step S6, after finishing automatic feedback correction according to the correction offset, the main adjusting parameters and feedback parameters of the dimming optical element are timely saved into a table look-up mode parameter file by utilizing the system parameter module 50; and then, the automatic feedback control module 60 is utilized to obtain the rule of influence of the change of the dimming parameter according to the beam line system on the change of the feedback parameter through machine learning updating according to the table look-up mode parameter file.
After the step S6, step S7 may further include: returning to step S5, the table look-up pattern parameter file saved in step S6 can thus be used for the next experimental light path alignment, as well as for machine learning affecting the law.
Therefore, under the condition that the light source shake, the gesture fluctuation of the dimming equipment, the movement motor shift and the like cause the shake of the light spot center at the four-knife slit to be even smaller in the experimental process, the automatic feedback correction of the automatic feedback control module 60 in the step S5 can maintain the collimation of the light path.
In consideration of serious emergency, such as error reporting of a beam line control program, the central light spot may have a larger deviation due to a fault of a moving motor of the light modulation element, and at this time, a current deviation of a current center of the exit slit system 20 with respect to an opening center of the exit slit system 20 may become very large. Therefore, the automatic feedback control module 60 is provided with a current deviation overrun threshold, and in the step S5, if the current deviation exceeds the current deviation overrun threshold, the automatic feedback control module 60 needs to give an error message alarm, and returns to the step S3, so that the experiment operator can find and reject the fault in time.
The specific requirement of the current deviation overrun threshold is determined according to the motor precision of the upstream light modulation element, and the actual measurement of multiple groups of data is required to be counted in a real experiment.
Through the steps, the center of the light path can be rapidly and accurately positioned, and meanwhile, the luminous flux of the sample at the real-time position is optimal, so that the experimental efficiency and the data quality can be effectively improved.
When the control program runs automatically, all data parameters are displayed on a display interface, and if special conditions such as light source stop, abnormal fluctuation of individual data, sample signal failing to meet the expected requirement and the like occur, necessary error warning information needs to be given, so that experiment operators can remove faults in time.
The automatic control program can realize the acquisition of the influence rule through big data analysis, machine learning and the like by a plurality of sets of data lists contained in the system parameter module, realize the automatic updating and the optimization of the system parameters in a certain energy range, and facilitate the realization of the automatic light path collimation in the step S5.
By the method, the collimation of the central light path and the optimal luminous flux experimental conditions can be rapidly realized, and meanwhile, the light beam center is fed back and corrected in real time and the maximum luminous flux is maintained in the experimental process. The manual dimming time is greatly shortened, the experimental efficiency is greatly improved, and the labor intensity of staff is reduced. Meanwhile, the invention is convenient for the user to remotely control in cooperation with an automatic data acquisition mode, and improves the operability of the experiment. In addition, the invention can be expanded to other different experimental methods, and has great promotion effect on the development of different scientific fields.
According to the automatic feedback dimming device system for the beam line station, when the center of a light spot shakes greatly due to factors such as energy replacement, element switching, electron beam cluster fluctuation of a storage ring, disturbance of a moving mechanism of a beam line optical element and the like, the deviation of the current of four edges of an emergent slit is monitored in real time, the deviation direction and the deviation amount of the center position of the light beam in an experiment are determined easily, so that the posture of the beam line optical element is automatically fed back and corrected, the central light spot always irradiates the position of the sample by correcting the posture of an upstream optical element, the light spot flux and the position on the surface of the sample are kept constant, and the experimental efficiency and the experimental data quality are improved.
In addition, for long-time running experiments, the invention adopts the automatic feedback control module to carry out automatic feedback, so that the offset of the beam center is monitored and corrected in real time, and compared with manual adjustment by operators, the automatic adjustment is free from staring at a running state at any time, is convenient for users to remotely operate and control, and greatly reduces the labor intensity of workers. The high-frequency automatic feedback adjustment improves the efficiency of the experiment, and simultaneously ensures the experiment persistence and the data quality.
Furthermore, the upstream beam line is provided with a plurality of dimming elements, and the beam center offset is the result of the influence of a plurality of factor variables.
In summary, the invention integrates the adjustment parameters and the feedback parameters of the beam line system into the automatic control program module, can realize real-time monitoring and correction of luminous flux change during experiments, and simultaneously maintains the constant central position of the optical path, thereby realizing long-time operation of the experiments under the optimal experimental conditions, greatly improving the experimental efficiency, facilitating remote operation control of users and greatly reducing the labor intensity of experimental operation. The invention has important significance for improving the efficiency and experimental quality of the beam line station experiment, has guidance for the construction of other line stations with similar devices, and provides technical support for the construction of new light sources and similar line stations.
The above-described exemplary embodiments of the present invention are only exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and various changes can be made in the above-described embodiments of the present invention. All simple, equivalent changes and modifications made in accordance with the claims and the specification of this application fall within the scope of the patent claims. The present invention is not described in detail in the conventional art.
Claims (10)
1. The automatic feedback dimming system of the beam line station is characterized by comprising a local area network, and a beam line system, an emergent slit system, an experiment station, a system parameter module and an automatic feedback control module which are connected with the local area network;
the light beam line system, the emergent slit system and the experiment station are sequentially arranged, the emergent slit system is used as a dimming optical element and comprises four knife edges, the experiment station is provided with a light intensity detection system, and the light intensity detection system comprises a gold mesh and a photodiode which are arranged at the experiment station;
the system parameter module is configured to store main adjustment parameters and feedback parameters of the dimming optical element in a table look-up mode parameter file, wherein the main adjustment parameters of the dimming optical element comprise dimming parameters of a beam line system and dimming parameters of an emergent slit system, and the feedback parameters comprise photocurrent signals of four edges of the emergent slit system, a gold wire and luminous flux signals of a photodiode;
The automatic feedback control module is set to acquire control authority of main adjusting parameters of the dimming optical element, read authority of real-time feedback parameters and acquire authority of table lookup mode parameter files from the system parameter module, and obtain an influence rule of the change of the dimming parameters of the beam line system on the change of the feedback parameters according to the table lookup mode parameter files; reading photocurrent signals of four knife edges of the exit slit system in real time, and determining current deviation of the current center of the exit slit system relative to the opening center of the exit slit system in real time through the photocurrent signals of the four knife edges of the exit slit system; when the current deviation is larger than a set current deviation threshold, determining a correction offset of the dimming parameter of the beam line system according to the influence rule, and correcting the dimming parameter of the beam line system according to the correction offset, wherein the correction offset of the dimming parameter of the beam line system refers to the offset of the parameter when the photocurrent signal values of the left and right knife edges of the exit slit system are the same and the photocurrent signal values of the upper and lower knife edges are the same.
2. The automatic feedback dimming system of the beam-line station according to claim 1, wherein the beam-line system comprises a light source, a plane mirror, a monochromator grating and a focusing mirror which are sequentially arranged and serve as dimming optical elements, and the dimming parameters of the beam-line system comprise an incident light energy value E of the light source, xyz three-dimensional coordinates of the plane mirror and the focusing mirror and angles of meridian and sagittal directions, and linear density of the monochromator grating, cff values, xyz three-dimensional coordinates and angles of meridian and sagittal directions; the dimming parameters of the exit slit system comprise the center coordinates of the opening and the size of the opening of the exit slit system.
3. The automatic feedback dimming system of the beam-line station of claim 2, wherein the light source is an undulator, and the dimming parameters of the beam-line system further comprise Gap and Shift values of the undulator.
4. An automatic feedback dimming system of a beam line station as claimed in claim 1 or 2, each dimming optical element being configured with an encoder and a grating scale to obtain the primary tuning parameters of the dimming optical element.
5. The automatic feedback dimming system of the beam line station according to claim 1, wherein the outgoing slit device is provided with a photoelectric signal conversion device electrically connected with four knife edges of the four-knife slit respectively and a current-to-voltage conversion device connected with the photoelectric signal conversion device.
6. The automatic feedback dimming system of a beam line station according to claim 1, wherein the gold wire is disposed at a front end of an experiment station, the photodiode is disposed at a position near a rear end of a sample inside the experiment station, and a pinhole diaphragm disposed at the front end of the gold wire is disposed in the experiment station.
7. An automatic feedback dimming method for a beam line station, comprising:
step S1, an automatic feedback dimming system based on a beam line station is constructed, and the automatic feedback dimming system comprises a local area network, and a beam line system, an emergent slit system, an experiment station, a system parameter module and an automatic feedback control module which are connected with the local area network; the light beam line system, the emergent slit system and the experiment station are sequentially arranged, the emergent slit system is used as a dimming optical element and comprises four knife edges, the experiment station is provided with a light intensity detection system, and the light intensity detection system comprises a gold mesh and a photodiode which are arranged at the experiment station;
Step S2, acquiring control authority of main adjustment parameters of the dimming optical elements through a local area network by utilizing an automatic feedback control module, reading real-time feedback parameters and acquiring authority of a table look-up mode parameter file from a system parameter module, and obtaining influence rules of the change of the main adjustment parameters of different dimming optical elements on the change of the feedback parameters according to the table look-up mode parameter file;
the main adjusting parameters of the dimming optical element comprise a dimming parameter of a beam line system and a dimming parameter of an emergent slit system, and the feedback parameters comprise photocurrent signals of four edges of the emergent slit system, a gold mesh and luminous flux signals of a photodiode;
step S3, under the condition that the opening size of the emergent slit system is enlarged, attempting to call a lookup table mode parameter file in a corresponding range according to the current experimental condition, and if the call is successful, using the dimming parameter of the beam line system in the lookup table mode parameter file as an initial correction offset of the main adjusting parameter of the dimming optical element, and correcting the dimming optical element of the beam line system; otherwise, manually adjusting the dimming optical element of the beam line system, and storing the manual adjustment result into a table look-up mode parameter file in the form of a parameter list by using the system parameter module as an optimal parameter of the dimming parameter of the beam line system;
S4, measuring signals of the photodiodes while scanning by integrally moving the emergent slit system, and calibrating the position of the opening center of the emergent slit system;
s5, utilizing an automatic feedback control module to read photocurrent signals of four knife edges of the emergent slit system in real time, and determining current deviation of the current center of gravity of the emergent slit system relative to the opening center of the emergent slit system; when the current deviation is larger than a set current deviation threshold value, determining a correction offset of the dimming parameter of the beam line system according to the influence rule of the change of the dimming parameter of the beam line system on the change of the feedback parameter, correcting the dimming parameter of the beam line system according to the correction offset, wherein the correction offset of the dimming parameter of the beam line system refers to the offset of the parameter when the photocurrent signal values of the left and right knife edges of the outgoing slit system are the same and the photocurrent signal values of the upper and lower knife edges are the same, otherwise, not correcting;
step S6, after finishing correction according to the correction offset, the main adjusting parameters and the feedback parameters of the dimming optical element are timely saved into a table look-up mode parameter file by utilizing a system parameter module; and then, an automatic feedback control module is utilized, an influence rule of the change of the dimming parameter according to the beam line system on the change of the feedback parameter is obtained through machine learning updating according to the table look-up mode parameter file and simulation calculation, and the step S5 is returned.
8. The automatic feedback dimming method of the beam-line station according to claim 7, wherein the step S3 specifically comprises:
step S31, setting an incident light energy value of a light source as a current experimental condition, and amplifying the opening size of an emergent slit system; utilizing an automatic feedback control module to attempt to retrieve a table look-up mode parameter file in a corresponding range of the incident light energy value of the current light source in the system parameter module;
step S32, judging whether a stored lookup table mode parameter file in a corresponding range exists, if so, attempting to call successfully, then carrying out step S33, otherwise, carrying out step S34;
step S33, the table look-up mode parameter file of the latest date is called, the optimal parameter of the dimming parameter of the beam line system in the table look-up mode parameter file is used as the initial correction offset of the main adjusting parameter of the dimming optical element, and the dimming optical element is corrected by reading the initial correction offset through the dimming optical element;
if the absolute value of the difference between the set incident light energy value and the called incident light energy value of the lookup table mode parameter file is smaller than 5eV, directly performing step S4; otherwise, after the initial correction offset is read in by the dimming optical element to correct the dimming optical element, step S34 is performed;
Step S34, manually adjusting the dimming parameters of the beam line system in the main adjusting parameters of the dimming optical element according to the feedback parameters in the system parameter module, taking the manual adjusting result as the optimal parameters of the dimming parameters of the beam line system, manufacturing a corresponding table look-up mode parameter file in the form of a parameter list, and then executing step S4.
9. The automatic feedback dimming method of a beam-line station according to claim 7, wherein when the step S4 employs manual adjustment calibration, the step S4 includes:
step S41, the automatic feedback control module is set to be in a manual mode, coordinates are calibrated by taking a focusing optical element in an experiment station as a center, and the center of an optical path is set; opening sizes of four knife edges of the emergent slit system are enlarged, detection is carried out by adopting a photodiode, and the change of luminous flux signal values of the photodiode is observed while the dimming parameter is regulated; then, recording and storing the dimming parameters of the corresponding beam line system when the luminous flux signal value of the photodiode is maximum as optimal parameters in a form of a parameter list to a corresponding table look-up mode parameter file;
step S42, gradually reducing the opening size of the emergent slit system, adjusting the position of the opening center of the emergent slit system, observing the change of the signal of the photodiode, and selecting the position of the opening center of the emergent slit system corresponding to the highest luminous flux to be calibrated as the calibrated opening center;
Step S43, designating the opening size of the exit slit system, under the designated opening size, taking the designated opening center as an origin, integrally moving the exit slit system in the direction vertical to the light beam to scan, recording the luminous flux signal value of the photodiode when the opening center is at different scanning positions while scanning, automatically positioning the optimal position of the opening center according to the luminous flux signal value of the photodiode, and driving the opening center of the exit slit system to the optimal position;
then, the optimal position of the opening center of the emergent slit system corresponding to different opening sizes and the luminous flux signal value of the photodiode are used as optimal parameters and stored in a table look-up mode parameter file of corresponding incident light energy values in a parameter list mode;
when the system parameter module has saved the current optimal parameters of the dimming parameters of the beam line system and the dimming parameters of the exit slit system under the incident light energy value, the step S4 adopts automatic adjustment calibration, and the step S4 includes:
step S41', determining whether the gold mesh is inserted into the optical path during the experiment according to the experiment requirement; if the gold wire is inserted into the light path during the experiment, the luminous flux signal value of the photodiode is used as the luminous flux signal value recorded in the step S42', otherwise, the luminous flux signal value of the gold wire is used as the luminous flux signal value recorded in the step S42';
Step S42', the automatic feedback control module automatically imports the optimal parameter under the current incident light energy value, and under the condition that the dimming parameter of the light beam line system is regulated to the optimal parameter and kept motionless, the opening center of the emergent slit system integrally moves in the direction perpendicular to the light beam by taking the optimal parameter of the dimming parameter of the emergent slit system as an origin to perform automatic scanning, the luminous flux signal values of the opening center at different scanning positions are obtained by recording while scanning, and the optimal position of the corresponding opening center when the luminous flux signal value is maximum is found and the opening center of the emergent slit system is driven to the optimal position; and storing the main adjusting parameters of the dimming optical element when the luminous flux signal value is maximum as optimal parameters into a table look-up mode parameter file.
10. The automatic feedback dimming method of a beam line station according to claim 7, wherein the current deviation of the current center of gravity of the exit slit system with respect to the opening center of the exit slit system comprises a left-right current deviation and an up-down current deviation, wherein the left-right current deviation S RL And up-down current deviation S UD The method comprises the following steps:
S RL = (S R -S L ) / (S R +S L )，
S UD = (S U -S D ) / (S U +S D )，
wherein S is R Is a photocurrent signal of a right knife edge, S L Is a photocurrent signal of a left knife edge, S U Is a photocurrent signal of an upper knife edge, S D Is a photocurrent signal of the lower knife edge.
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