Researching Of The Spm System Based On A Piezo-electrical Micro-fork Probe

Scanning Probe Microscope is used widely in MEMS, chemistry, biomedicine and other fields. This thesis researches a SPM system with piezo-electrical micro- fork probe.The accomplished tasks include the following parts: First the probe of SPM, Introduces the principle of the system probe and tests its property; Second, the hardware circuit section, phase locked loop(PLL) worked as actuating circuit to capture and follow the frequency of probe, a improved one is developed based on the former. This paper explains the principle of PLL employed in the project and the implementation of the improved circuit. The hardware circuit also includes the filter and amplifier for obtaining the RMS value of probe's synchronic signal and the phase signal of PLL; Third, the closed-loop control part. All the components of SPM system are assembled to form a voltage amplitude feedback loop as well as a phase feedback loop; Forth, based on Visual C++, the systems tip and sample approach program, system's dynamic response test program and the scanning controlling program are designed which are used in the experiments of system performance. Last, sample scanning are conducted to obtain the surface topographic and phasic pictures. Analysis of these pictures verified the system's effectiveness.According to the results presented in this paper, the SPM has relatively high vertical space resolution and it can be used for high step sample's micron topographic measurement.