- Title
- Lyapunov estimation for high-speed demodulation in multifrequency atomic force microscopy
- Creator
- Harcombe, David M.; Ruppert, Michael G.; Ragazzon, Michael R. P.; Fleming, Andrew J.
- Relation
- Beilstein Journal of Nanotechnology Vol. 9, p. 490-498
- Publisher Link
- http://dx.doi.org/10.3762/bjnano.9.47
- Publisher
- Beilstein-Institut
- Resource Type
- journal article
- Date
- 2018
- Description
- An important issue in the emerging field of multifrequency atomic force microscopy (MF-AFM) is the accurate and fast demodulation of the cantilever-tip deflection signal. As this signal consists of multiple frequency components and noise processes, a lock-in amplifier is typically employed for its narrowband response. However, this demodulator suffers inherent bandwidth limitations as high-frequency mixing products must be filtered out and several must be operated in parallel. Many MF-AFM methods require amplitude and phase demodulation at multiple frequencies of interest, enabling both z-axis feedback and phase contrast imaging to be achieved. This article proposes a model-based multifrequency Lyapunov filter implemented on a field-programmable gate array (FPGA) for high-speed MF-AFM demodulation. System descriptions and simulations are verified by experimental results demonstrating high tracking bandwidths, strong off-mode rejection and minor sensitivity to cross-coupling effects. Additionally, a five-frequency system operating at 3.5 MHz is implemented for higher harmonic amplitude and phase imaging up to 1 MHz.
- Subject
- atomic force microscopy (AFM); demodulation; digital signal processing; field-programmable gate array (FPGA); high-speed; Lyapunov filter; multifrequency
- Identifier
- http://hdl.handle.net/1959.13/1392180
- Identifier
- uon:33362
- Identifier
- ISSN:2190-4286
- Rights
- © 2018 Harcombe et al.; licensee Beilstein-Institut. This is an Open Access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The license is subject to the Beilstein Journal of Nanotechnology terms and conditions: (https://www.beilstein-journals.org/bjnano)
- Language
- eng
- Full Text
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