Dual frequency modulation with two cantilevers in series: a possible means to rapidly acquire tip–sample interaction force curves with dynamic AFM

The ability of atomic force microscopy (AFM) to acquire tip-sample interaction force curves has allowed researchers to understand the mechanical behavior of numerous materials at the nanoscale. However, AFM force spectroscopy with the most commonly used techniques can be a slow process for non-uniform samples, as it often requires the measurement to be performed at one fixed surface point at a time. In this paper we present two dynamic AFM based spectroscopy methods, one requiring operation in single-frequency-modulation mode and another using dual-frequency-modulation, which could allow a more rapid acquisition of topography and tip-sample interaction force curves. Numerical simulation results are provided along with discussions on the benefits and limitations of both.

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A novel optical coherent domain reflectometer with dual frequency modulation

10.1117/12.2185269 ◽

2015 ◽

Author(s):

L. Liu ◽

Q. Liu ◽

X. Fan ◽

L. Ma ◽

J. Du ◽

...

Keyword(s):

Frequency Modulation ◽

Dual Frequency ◽

Coherent Domain

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Motion Coordination of Two Robots in Cartesian Space Based on Mechanical Impedance

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.613.53 ◽

2014 ◽

Vol 613 ◽

pp. 53-59 ◽

Cited By ~ 1

Author(s):

Adam Slota

Keyword(s):

Mechanical Impedance ◽

Interaction Force ◽

Linear Increase ◽

Dimensional Case ◽

Motion Coordination ◽

Coordinated Motion ◽

Simulation Experiments ◽

Cartesian Space ◽

Motion Speed ◽

In Series

Coordinated motion of two robots in Cartesian space is considered in the paper. Coordinated trajectory is generated as the sum of two motions: programmed and corrective. The corrective motion aims at limitation of the interaction force between robots. For calculation of the corrective motion speed the idea of mechanical impedance is used. As a measure of force interactions between robots change of distance between robots TCPs is used. Simulation experiments carried out for one dimensional case show that application of impedance based correctors results in the linear growth of change of distance between robots TCPs for constant difference between robots programmed speeds. Thus a modification of impedance based correctors is proposed. The modification consists in introduction of an integrating element in series with impedance corrector. Simulation tests for the modified correctors provide improved results – magnitude of change of distance is decreased. Linear increase of change of distance for impedance corrector is changed into a constant non zero value, whereas constant non zero value is changed into zero value. Simulation results for two dimensional case of coordinated motion are also presented.

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Suppression of backscattering-induced noise in a resonator optic gyro by the dual-frequency modulation method

Optics Communications ◽

10.1016/j.optcom.2019.124766 ◽

2020 ◽

Vol 459 ◽

pp. 124766

Author(s):

Haoyu Wang ◽

Wenyao Liu ◽

Ziwen Pan ◽

Yu Tao ◽

Jian Niu ◽

...

Keyword(s):

Frequency Modulation ◽

Modulation Method ◽

Dual Frequency

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A Parallel-Phase Demodulation-Based Distance-Measurement Method Using Dual-Frequency Modulation

Applied Sciences ◽

10.3390/app10010293 ◽

2019 ◽

Vol 10 (1) ◽

pp. 293

Author(s):

In-Gyu Jang ◽

Sung-Hyun Lee ◽

Yong-Hwa Park

Keyword(s):

Frequency Modulation ◽

Measurement Method ◽

Continuous Wave ◽

Measurement Range ◽

Distance Measurement ◽

Measurement Technology ◽

Dual Frequency ◽

Distance Measurements ◽

Time Required ◽

Phase Demodulation

Time-of-flight (ToF) measurement technology based on the amplitude-modulated continuous-wave (AMCW) model has emerged as a state-of-the-art distance-measurement method for various engineering applications. However, many of the ToF cameras employing the AMCW process phase demodulation sequentially, which requires time latency for a single distance measurement. This can result in significant distance errors, especially in non-static environments (e.g., robots and vehicles) such as those containing objects moving relatively to the sensors. To reduce the measurement time required for a distance measurement, this paper proposes a novel, parallel-phase demodulation method. The proposed method processes phase demodulation of signal in parallel rather than sequentially. Based on the parallel phase demodulation, 2π ambiguity problem is also solved in this work by adopting dual frequency modulation to increase the maximum range while maintaining the accuracy. The performance of proposed method was verified through distance measurements under various conditions. The improved distance measurement accuracy was demonstrated throughout an extended measurement range (1–10 m).

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High sensitive detection of trace gases by dual frequency modulation

Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing ◽

10.1109/comeas.1995.472378 ◽

2002 ◽

Author(s):

N. Takeuchi ◽

T. Yamamoto ◽

A. Mugino ◽

T. Omatsu ◽

M.A. Gubin ◽

...

Keyword(s):

Frequency Modulation ◽

Trace Gases ◽

Sensitive Detection ◽

Dual Frequency

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Accurate, explicit formulae for higher harmonic force spectroscopy by frequency modulation-AFM

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.6.14 ◽

2015 ◽

Vol 6 ◽

pp. 149-156 ◽

Cited By ~ 6

Author(s):

Kfir Kuchuk ◽

Uri Sivan

Keyword(s):

Frequency Modulation ◽

Short Range ◽

Oscillation Amplitude ◽

Complete Information ◽

Interaction Force ◽

Harmonic Force ◽

Interaction Range ◽

Present Letter ◽

Explicit Formulae ◽

Higher Harmonic

The nonlinear interaction between an AFM tip and a sample gives rise to oscillations of the cantilever at integral multiples (harmonics) of the fundamental resonance frequency. The higher order harmonics have long been recognized to hold invaluable information on short range interactions but their utilization has thus far been relatively limited due to theoretical and experimental complexities. In particular, existing approximations of the interaction force in terms of higher harmonic amplitudes generally require simultaneous measurements of multiple harmonics to achieve satisfactory accuracy. In the present letter we address the mathematical challenge and derive accurate, explicit formulae for both conservative and dissipative forces in terms of an arbitrary single harmonic. Additionally, we show that in frequency modulation-AFM (FM-AFM) each harmonic carries complete information on the force, obviating the need for multi-harmonic analysis. Finally, we show that higher harmonics may indeed be used to reconstruct short range forces more accurately than the fundamental harmonic when the oscillation amplitude is small compared with the interaction range.

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