Research On Key Technologies Of Large-Range Scanning Imaging System

As an important tool for nanotechnology research,atomic force microscope(AFM)has been widely used in life science,precision manufacturing,electronic information and other fields.It is of great significance for the further application of AFM to develop large scanning imaging system.Aiming at the need of enlarging the scanning imaging range of AFM and ensuring the imaging resolution at the same time,this paper studies the key technology of large-range scanning imaging system.The main research work is shown as follows:The optical analysis of the measurement system is conducted,the magnification ratio of the optical lever,the position change of the light spot and its degree of coupling when the probe is rotated in the transverse direction and vertical direction are studied.The imaging mode of the system is determined,and the scanning positioning system based on macro-micro driving is adopted for scanning,scanning area selection,step motion and z-direction needle.The sinusoidal scanning mode of fast and slow-axis based zigzag scanning method is determined to meet the needs of fast and high-quality imaging.The mechanical design of flexure-based scanner is carried out and the analysis of its dynamic and static characteristics is conducted.In order to solve the hysteresis and creep of the flexure-based scanner,a feedforward-feedback control strategy is proposed in which asymmetric Bouc-Wen model is introduced as feedforward model and PI model as feedback model.Then the parameters of the feedforward model are identified and the proportional and integral coefficients of the PI model are determined.An experimental platform is built to verify the effect of the established control strategy.The results show a linear displacement output and good tracking accuracy along one dimension and two dimensions.The hardware and software parts of the system are built based on the scheme of large-range scanning imaging system.The control and data acquisition-processing program system are developed to realize motion control,real-time imaging and data storage.Static analysis is carried out for the mechanical part of the large-range scanning imaging system,the results prove that the system has good property.The parameter calibration of the large-range scan imaging system is carried out,the sensitivity of the dynamic strain gauge and PSD is calibrated,and the environmental noise of the system is tested.The experiment is carried out,and the scanning test of standard grating sample proves that high quality images under the condition of 10 Hz and 200×200 pixel can be obtained,and the single image obtained from the experiment is spliced.The result shows that the proposed system can achieve a wide range of highresolution micro-imaging.