| A series of surface-measuring instruments which can achieve atomic-scale resolution are entitled"Scanning Probe Microscope"collectively, such kind of instruments are widely used in metrology, MEMS, chemistry, biomedicine and other fields. In this study, develop a set of SPM based on a new-style stylus fabricated by PVDF (Polyvinilidene Fluoride) film.The following is the primary work which has been completed. In the section of tungsten probe preparation, discuss the advantages and disadvantages of several electrochemical corrosion methods, and then, take some improvements purposely to develop a modified DC electrochemical grinding technique. In this section, also have the analysis of factors that impact on probes shape when prepared by this means. About the stylus, expatiate on the structure and operating principle of the new-style tapping-mode stylus firstly, and then, optimize the parameters involved through series of experiments, determine the performance parameters, such as resonant frequency, signal amplitude, elastic constant, and quality factor, etc. In order to detect the tiny elastic distortion and accomplish the signal transformation, charge amplifier, voltage amplifier, RMS-to-DC and band-pass filter are designed respectively. In closed-loop control system, all the components of the SPM system are assembled to form a voltage-amplitude feedback loop, and then improve the control program to fit the characteristic of this feedback. According to the system performance tests, set value for voltage comparing, P and I constants, scanning velocity and other parameters are determined in order to obtain the best scanned pictures. And then give performance analysis of the SPM system based on these pictures and tests.The research findings in this paper verify that the new-style SPM has characteristics of high resolution, various material adapted well, nondestructively, be able to scan surface with altitude difference in sub-millimeter dimension. |
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