Design Of A Micro/Nano Scale Based Sample Scanning Imaging System

Atomic force microscope(AFM)is a useful tool in the nanoscale measurement,the ability of high precision measurement and nano manipulation expand its use in mechanical,biological and life science.This dissertation focus on designing a sample scanning imaging system that can provide fast scanning with high precision.First,the working principle,component and working mode of the sample scanning imaging system are introduced.The system captures the morphology of the sample by adopting optical lever,which is composed of AFM probe,position sensitive detector(PSD)and laser diode.Specifically,the system performs constant force contact scanning with probe fixed and sample scanning.Then the main parts of the system are devised,manufactured and purchased.The system consists of position detecting mechanism,system holder,base,fast positioning system and scanner.All parts are customized according to requirement and it is easy to assemble because there is no optical accessories.The scanner,which is driven by the piezoelectric actuators,adopts flexible hinge mechanism and can provide high-speed displacement output with high precision and low motion coupling error.After that,the parameters of the system are calibrated.To be precise,calibration includes the position sensor of the scanner,PSD signal and close loop control.Then the program is designed according to the system functions.There are five modules including fast positioning program,A/D program,probe in/out program and imaging program.Finnaly,experiments like different sample imaging with different scanning speeds and resolutions,lateral-force and deflection imaging,feedforward compensation for scanner hysteresis and force spectroscopy are conducted.The proposed sample scanning imaging system provides good scanning performance with high accuracy and fast scanning speed.There is no optical accessories,operation is simple without complicated optical focusing.The scanner,which has high natural frequency and rigidity,adopts close loop motion control,so that the system is robust.The dissertation expounds how the system is realized from the aspects of structural design,parameter calibration,software programming and experimental verification,it has important guiding significance for the research of nanotechnology.