Dick, Andrew J.2012-07-032012-07-032011-042011Eason, Richard Parker. "Optical Lever Measurement Accuracy for Off-Resonance Atomic Force Microscopy." (2011) Master’s Thesis, Rice University. <a href="https://hdl.handle.net/1911/64427">https://hdl.handle.net/1911/64427</a>.https://hdl.handle.net/1911/64427This research evaluates measurement accuracy in optical lever-based atomic force microscopy (AFM) for off-resonance conditions and parameter variations. Under controlled conditions and correct calibration, AFM provides researchers with the ability to accurately observe and manipulate matter on the micro- and nano-scale. Accuracy of imaging and nano-manipulation operations are directly correlated to the accuracy with which the displacement of the probe is measured. The optical lever method, a common displacement measurement technique employed in AFM, calculates probe displacement based on a calibration that assumes a consistent response profile throughout operation. Off-resonance excitation and tip-sample interaction forces during intermittent contact mode AFM can alter this response profile. Standard tapping-mode operation at the fundamental frequency is observed to be robust to changes in effective stiffness, maintaining accurate measurements for all laser spot positions considered. A nominal laser spot position between Xp = 0.5 and 0.6 is determined to most accurately predict displacement for off-resonance excitation during both free response and intermittent contact condit ions. Measurement accuracy for off-resonance tapping- mode is more directly correlated to changes introduced to the interaction force profile than choice of spot position.81 ppapplication/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.Mechanical engineeringMaterials scienceThesisEasonRTHESIS M.E. 2011 EASON