Investigation of position detectors for atomic force microscopes

Vorbringer-Dorozhovets, Nataliya; Mastylo, Rostyslav; Manske, Eberhard

doi:10.1088/1361-6501/aad397

Cited by 8 publications

(4 citation statements)

References 46 publications

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“…Although AFM manufacturers have considered using optical interferometry, it is bulkier [1,4]. However, the sensitivity of an optical interferometer can be higher and has the advantage of traceability [5]. From a metrology point of view, the optical lever technique has many disadvantages, since it does not measure the cantilever displacement, but only the local angular deflection of the cantilever.…”

Section: Der Waalsmentioning

confidence: 99%

Multiple-fibre interferometry setup for probe sample interaction measurements in atomic force microscopy

Klapetek

Yacoot

Hortvík

et al. 2020

Meas. Sci. Technol.

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Atomic force microscopy (AFM) often relies on the assumption that cantilever bending can be described by simple beam theory and that the displacement of the tip can be evaluated from the cantilever angle. Some more advanced metrological instruments use free-space or fibre interferometers for measuring the position of the cantilever apex directly, thereby simplifying the metrology traceability chain. The next logical development, covering measurements of both the cantilever apex position and its deformation due to lateral forces acting during different AFM measurement regimes, is presented in this paper. It is based on using a set of closely packed fibre interferometers that can be used to determine localised bending of the cantilever at different positions along the cantilever. This can be used for detection of cantilever deformation beyond classical beam theory, and can yield both better understanding of sources of uncertainty in individual AFM force–distance measurements and more accurate scanning in constant height mode in high-speed AFM applications.

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Section: Der Waalsmentioning

confidence: 99%

Multiple-fibre interferometry setup for probe sample interaction measurements in atomic force microscopy

Klapetek

Yacoot

Hortvík

et al. 2020

Meas. Sci. Technol.

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“…Other researchers have investigated sensitivity of different detectors techniques for AFM applications such as an interferometer, optical lever, and focus sensor and compared each other. 29 Another method proposed the integration of metasurfaces positioned at the back of an AFM cantilever to improve the optical lever sensitivity. 30…”

Section: Introductionmentioning

confidence: 99%

Effects of laser spot positioning with optical beam deflection method on tapping mode and bimodal AFM

Putnam

Damircheli

Eslami

2020

Proceedings of the Institution of Mechanical Engineers, Part K:

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This work focuses on the importance of laser location and its effect on contact mode, tapping mode, and bimodal AFM both theoretically and experimentally. It is found that the current guidelines in the field might lead to mischaracterization of matter especially in bimodal AFM. A numerical study is done for a cantilever with its tip located at the end while interacting with two different polymers of Polystyrene (PS) and Low-density polyethylene (LDPE). Different observables are recorded at the end of the cantilever, 80% of its length, and 60% of its length. These results are verified by experiments in contact mode, tapping mode and bimodal AFM. Bimodal AFM observables are converted to energy quantities (i.e., virial and dissipated power) which are used to characterize soft matter in this field. Similar to simulation, for each of these measurements three different laser locations are selected. Finally, it is found there are certain locations on the cantilever that should be avoided for placing the laser while exciting higher eigenmodes. Hence, locating the laser around 80% of its length while performing bimodal AFM with the first and second eigenmodes on polymer surfaces can decrease phase contrast. It is concluded that: (1) contact mode AFM on stiff surfaces might not be effected by change of laser location, (2) misalignment of laser can cause up to 40% of mischaracterization in tapping mode and (3) 10% of phase contrast reduction in addition to 20% percent of reduction in amplitude oscillations in bimodal AFM. It is shown this can lead to mischaracterization of material. By positioning the laser location closer to the clamped end of the cantilever, surface indentation can occur. Although this is considered as a surface damage in soft matter imaging, it can be considered as a new capability of multifrequency AFM for surface modification.

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“…By detecting the cantilever deflection together with the precalibration of its spring constant, the forces are quantified to serve as feedback signals for tip-sample distance control during scanning or to characterize many physical properties [27,28]. In most conventional AFM systems, the deflection is sensed by using the optical beam deflection technique [29]. A laser beam is focused on the back side of the cantilever near its free end and the reflected beam is monitored by a position sensitive photodetector (PSD).…”

Section: Introductionmentioning

confidence: 99%

Metasurface-enhanced optical lever sensitivity for atomic force microscopy

et al. 2019

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We proposed the integration of metasurfaces on atomic force microscopy (AFM) cantilevers to improve the optical lever sensitivity. The metasurface positioned at the back of an AFM cantilever enables anomalous reflection of the laser beam and provides a nonlinear relationship between the incidence and reflection angles following the generalized Snell's law. Therefore, the displacement of the reflected laser spot at the photodetector can be amplified. The metasurface was composed of 30 nm thick Au nano-discs with different diameters in an array of 1500 nm×300 nm super cells. Using the fabricated metasurface mounted on a precise angle dial and a macroscale cantilever as prototypes, the concept of a metasurface-enhanced cantilever was experimentally ascertained. Results proved that the optical lever sensitivity can be easily increased. Finite element analysis showed that integration of the thin metasurface does not have a significant impact on the cantilever's mechanical properties including stiffness and eigenfrequencies. The proposed metasurface-enhanced optical lever sensitivity may have potential applications in improving functional performances of AFM instruments and cantilever-based sensors, such as allowing much smaller imaging forces and boosting the signal-tonoise ratio.

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Investigation of position detectors for atomic force microscopes

Cited by 8 publications

References 46 publications

Multiple-fibre interferometry setup for probe sample interaction measurements in atomic force microscopy

Multiple-fibre interferometry setup for probe sample interaction measurements in atomic force microscopy

Effects of laser spot positioning with optical beam deflection method on tapping mode and bimodal AFM

Metasurface-enhanced optical lever sensitivity for atomic force microscopy

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