Abstract Submitted to the    NANOTUBE'04 Conference:

The single walled carbon nanotube (CNT) is adapted as a probe for the nanometer resolution displacement measurement. The system includes an oscillating CNT tip scanning in contact across a grating which contains the periodic pattern of metal and dielectric layers and is moving at a constant speed. The concept of the encoder design is to record contact trajectory between the tip and the grating would provide the kinematics displacement information. The amplitude of the tip oscillation is intentionally different from that of the grating pitches. Therefore the contact trajectory between the tip and grating can be divided into several components. In this study, the tip size of the single-walled CNT is 2~4 nm. The grating pitch is varied from 100 nm to 1 micron. The system design is presented by dynamic kinematics analysis using commercial software, MSC ADAMS. The analysis of the contact trajectory during the scanning under different design parameters has been conducted. The design parameters include the tip geometry, displacement amplitude and frequency of the probe, grating pitch and its speed. The analysis data show that during the scanning, the discontinuously contacts between probe and the grating surface have been strongly speed and oscillation dependent. The signal processing involving the pulse width modulation is applied for improvement of the displacement measurements. The simulation results illustrate the optimal design of the system using non-dimensional parameters as following: tip diameter η= 0.02, tip oscillation amplitude A*=0.9, and grating speed V*=0.02. The non-dimensional parameter is based on the metal pitch of the grating.