| Synchrotron radiation hard X-ray micro/nano probe technology is an important test method in the micro/nano field.Because of its nano-level resolution,it is widely used in materials,biology,chemistry and other research fields,which has greatly promoted the development of nanotechnology.At the same time,advances in nanotechnology,especially the rapid development of nano-materials and biology,have also posed great challenges to the technical research and functional expansion of nano-focusing systems.These challenges mainly include two aspects: first,the spatial resolution and accuracy of the nano-focusing system are important indicators to measure the performance of the nano-focusing system;second,the control technology of the nano-focusing system is an important condition to ensure the efficiency and accuracy of the nano-scale fast scanning experiment.This paper focuses on the key control technology of the nano-focusing system,aiming at the problem that the commonly used control algorithms cannot effectively deal with the multi-axis coupling of the sample scanning stage and the system uncertainty,it applies decoupling control and robust control to the closed-loop control of the scanning stage to improve the positioning accuracy and robustness.Aiming at the application of the nano-focusing system in the fast scanning fluorescence imaging experiment,a scanning technique combining nano-level positioning feedback control and scanning motion control is designed,and a method of synchronization triggering the fluorescence detection system by hardware is given.A fast scanning fluorescence imaging experiment system is established on the nano-focusing device,which achieves high spatial resolution precision measurement and control of nano-focusing system,and an efficient and accurate fast scanning fluorescence imaging experiment.The main research results obtained by the thesis are as follows:1.The sample scanning stage of the nano-focusing system is a multi-variable coupling system.Its internal structure is complex,and the various parts are coupled to each other.It is difficult to establish a mechanism model accurately.A multi-variable step response method is used to identify the three-input-three-output coupling parameter model of the scanning stage.It converts multivariate identification into multiple equivalent univariate identifications and effectively solves the modeling problem of complex coupled systems.The built model can accurately describe dynamic characteristics of the scanning stage and has high forecast accuracy.In order to solve the problem of the coupling of the scanning stage,coupling characteristics of the scanning stage are analyzed,and a series compensation decoupling control is added to the scanning stage system,so that the system can retain characteristics of the original main channel,and eliminate the cross effect of input and output.It achieves that coupled system is equivalent to a system with three independent control channels.Because the uncertainty of the scanning stage model structure,parameters and operating environment will greatly affect the nano-level positioning accuracy of the scanning stage,a robust control is applied to the closed-loop control of the scanning stage to ensure the nano-level positioning accuracy and stability under the influence of uncertainty,and enhance the robustness of scanning stage control system.2.In order to solve the problem that the electromagnetic interference in the control system affects the positioning resolution of the sample scanning stage,time domain and frequency domain characteristics of the electrical signal output by the controller are analyzed,an electromagnetic interference filter is developed.A differential mode common mode filter circuit is designed,it suppresses the differential mode common mode interference,and solves the problem of the controller output differential to single-ended.A low-pass filter circuit is designed to suppress the high-frequency harmonic interference in the electrical signal.Test results show that the filter greatly reduces the time-domain electromagnetic interference amplitude of the electrical signal output by the controller,and effectively reduces the minimum resolvable signal level,thereby reducing the influence of electromagnetic interference on the positioning resolution of the scanning stage.3.The drive control system and closed-loop control system performance of the scanning stage are tested,the scanning stage control system experimental device is built,and the control system software module is designed,test results show that the maximum mean error of the output voltage of the drive control system in the full-scale output range is about 0.03 V,and the accuracy of voltage output is not greater than ± 0.08%,and the output voltage curve of the drive control system has a good agreement with the expected voltage curve.The rise and fall times of drive control system to the full range 40 V step response are 431.4?s and 429.6?s,respectively.Through the role of closed-loop control system,the scanning stage achieves horizontal X and Y direction positioning resolution is about 2nm,and the vertical Z-direction positioning resolution is about 1nm.The positioning movement of1?m in either direction of scanning stage has steady-state error less than 5nm,at the same time,the amplitude of disturbance motion in other directions is less than 6nm.The positioning movement of 10?m in either direction of the scanning stage has steady-state error less than 6nm,at the same time,the amplitude of disturbance motion in other directions is less than 6nm.It proves that the designed control method is feasible to realize nano-level spatial resolution and nano-level positioning motion.4.Fast scanning fluorescence imaging experiment is carried out based on the designed control system,a scanning technique combining nano-level positioning feedback control and scanning motion control is designed,so that the sample has nano-level positioning accuracy during the continuous scanning process,and the positioning accuracy of light spot on the sample is improved.A method of synchronization triggering the fluorescence detection system by hardware is given.This method makes the position of the sample that obtains the fluorescence count strictly consistent with the coordinates of the pixel points of the fluorescence data,and enhances the accuracy of fluorescence imaging.A fast scanning fluorescence imaging experiment system is established on the nano-focusing device,and element distribution images of a standard copper mesh are obtained,and an efficient and accurate nano-focusing system fast scanning fluorescence imaging experiment is realized,and it further verifies the feasibility of the designed control system. |
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