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Lyapunov estimation for high-speed demodulation in multifrequency atomic force microscopy.
David M Harcombe1, Michael G Ruppert1, Michael R P Ragazzon2
1School of Electrical Engineering and Computing, The University of Newcastle, Callaghan, NSW, 2308, Australia.
Beilstein Journal of Nanotechnology
|March 9, 2018
Summary
This study introduces a novel Lyapunov filter for faster, more accurate multifrequency atomic force microscopy (MF-AFM) signal demodulation. The new method overcomes limitations of traditional lock-in amplifiers, enabling advanced imaging capabilities.
Area of Science:
- Physics
- Materials Science
- Nanotechnology
Background:
- Multifrequency atomic force microscopy (MF-AFM) requires precise demodulation of cantilever-tip deflection signals.
- Traditional lock-in amplifiers have bandwidth limitations and require parallel operation for MF-AFM.
- Accurate amplitude and phase demodulation are crucial for z-axis feedback and phase contrast imaging in MF-AFM.
Purpose of the Study:
- To develop a high-speed demodulation technique for MF-AFM.
- To address the bandwidth limitations of conventional lock-in amplifiers.
- To enable advanced imaging modes in MF-AFM through efficient multifrequency signal processing.
Main Methods:
- Implementation of a model-based multifrequency Lyapunov filter.
- Utilizing a field-programmable gate array (FPGA) for real-time processing.
- Experimental verification of system performance, including tracking bandwidth and off-mode rejection.
Main Results:
- The proposed Lyapunov filter achieves high-speed MF-AFM demodulation.
- Demonstrated high tracking bandwidths and strong rejection of out-of-band signals.
- Successful implementation of a five-frequency system for imaging up to 1 MHz.
Conclusions:
- The FPGA-based multifrequency Lyapunov filter offers a superior solution for MF-AFM demodulation.
- This method enhances imaging capabilities, particularly for higher harmonic analysis.
- The developed technique provides accurate and fast signal processing for advanced AFM applications.
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