Dynamic terrain following: nvCPD scanning technique improvement
Pyekh, Yury B.
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There is a large number of measurement techniques that is used for a surface inspection and a characterization of different types of materials. One of these techniques is a contact potential difference (CPD) scanning technique. In this project a non-vibrating contact potential difference (nvCPD) method is utilized to measure a work function and a topographical structure of a sample surface. A sample is mounted on a spindle that rotates at high speed. A nvCPD sensor detects work-function variations during movement above the sample surface. There are certain factors that create difficulties during the measurement process. A nonplanar sample surface, the spindle wobble and an incline of a mounted sample impede the safe (without impacting the surface) scanning at a close distance. The goal of this thesis was to implement a height sensor as a feedback device to dynamically control and adjust a CPD sensor flying height. Since a CPD signal is inversely proportional to the flying height, minimization of this height will enhance the signal magnitude, the signal-to-noise ratio and the resolution of measurements.