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This article provides a careful comparison between the electric and mechanical excitation of a tuning fork for shear force feedback in scanning probe microscopy, an analysis not found in present literature. A setup is designed and demonstrated for robust signal and noise measurements at comparable levels of physical movement of the probe. Two different signal amplification methods, combined with two excitation ways provide three possible configurations. For each method a quantitative analysis, supported by analytical elaboration and numerical simulations, is provided. Finally, it is shown that in practical circumstances electric excitation followed by detection with a transimpedance amplifier provides the best result. • Shear force feedback provides height feedback in scanning probe microscopy. • Quartz tuning forks outfitted with sharp probe suit purpose of shear force detection. • Sub-micrometer movement of a tuning fork induces interaction between tip and sample. • Possible tuning fork excitation and signal detection methods impact measurement. [ABSTRACT FROM AUTHOR]

Amendments have been made to International Standard ISO 18115-2:2010, extending the number of terms and, in a few cases where usage has changed, incorporating revisions. Part 2 covers 277 terms used in scanning probe microscopy as well as 98 acronyms. The terms cover words or phrases used in describing the samples, instruments and theoretical concepts involved. © 2014 Crown copyright. Surface and Interface Analysis © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Near-field scanning optical microscope (NSOM) measurements revealed that a linearly polarized Gaussian beam of wavelengthλ = 532 nm focused with a binary zone plate (ZP) of focal lengthλ, radius 7 μm, and groove depth 510 nm, fabricated in hydrogen silsesquioxane, produces a focal spot of size FWHM = (0.44 ± 0.02)λ, with the side lobes being lower than 10% of the intensity peak in the focus. Replacing the incident 532 nm wavelength with a 633 nm wavelength resulted in a 1.8 times shorter focal length and a tighter (in terms of wavelengths) focal spot of FWHM = (0.40 ± 0.02)λ. This value is smaller than the scalar diffraction-limited size in vacuum, FWHM = 0.51λ. This is the smallest focal spot so far experimentally obtained for a binary phase ZP and the root-mean-square deviation of the experimental curve from a FDTD simulation is 5%. We show that the metallic pyramid-shaped cantilever with a 100-nm-hole in the tip that is used in the NSOM is only able to detect the transverse electric field component. The FDTD simulation showed such a cantilever to be over 3 times more sensitive to the transverse electric field component than to the longitudinal one. Using the Richards–Wolf (RW) formulae, the near-focus intensity distribution can be calculated with 6% error for focal lengths larger than 4λ. It is usually assumed that the Debye theory and the RW formulae are only valid for focal lengths much larger than the incident wavelength. By FDTD simulation, we showed that when illuminating the ZP by a radially (rather than linearly) polarized beam, a decrease in the focal spot transverse size did not result in a substantially reduced total volume of focus (4%). [ABSTRACT FROM PUBLISHER]

Abstract: We have developed a simple and accurate method for calibrating the amplitude of vibration of quartz tuning fork sensors commonly used in atomic force- and near field optical-microscopy. Unlike interferometric methods, which require a complex optical setup, the method we present requires only a simple measurement of the electro-mechanical properties of the tuning-fork oscillator and can be performed in a matter of minutes without disturbing the experimental setup. Comparison with interferometric methods shows that an accuracy of better than few percent can be routinely achieved. [Copyright &y& Elsevier]

Near-field optical probe is the key element of a near-field scanning optical microscopy (NSOM) system. The key innovation in the first two NSOM experiments ( Pohl et al., 1984 ; Lewis et al., 1984 ) is the fabrications of a sub-wavelength optical aperture at the apex of a sharply pointed transparent probe tip with a thin metal coating. This paper discusses the routine use of focussed ion beam (FIB) to micro-machine NSOM aperture probes from the commercial silicon nitride cantilevered atomic force microscopy probes. Two FIB micro-machining approaches are used to form a nanoaperture of controllable size and shape at the apex of the tip. The FIB side slicing produces a silicon nitride aperture on the flat-end tips with controllable sizes varying from 120 nm to 30 nm. The FIB head-on drilling creates holes on the aluminium-coated tips with sizes down to 50 nm. Nanoapertures in C and bow tie shapes can also be patterned using the FIB head-on milling method to possibly enhance the optical transmission. A transmission-collection NSOM system is constructed from a commercial atomic force microscopy to characterize the optical resolution of FIB-micro-machined aperture tips. The optical resolution of 78 nm is demonstrated by an aperture probe fabricated by FIB head-on drilling. Simultaneous topography imaging can also be realized using the same probe. By mapping the optical near-field from a bow-tie aperture, optical resolution as small as 59 nm is achieved by an aperture probe fabricated by the FIB side slicing method. Overall, high resolution and reliable optical imaging of routinely FIB-micro-machined aperture probes are demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: The shape and size variations of the nanopatterns produced on a positive photoresist using a near-field scanning optical microscope (NSOM) are investigated with respect to the process variables. A cantilever-type nanoprobe having a 100nm aperture at the apex of the pyramidal tip is used with the NSOM and a He–Cd laser at a wavelength of 442nm as the illumination source. Patterning characteristics are examined for different laser beam power at the entrance side of the aperture (P in), scan speed of the piezo stage (V), repeated scanning over the same pattern, and operation modes of the NSOM (DC and AC modes). The pattern size remained almost the same for equal linear energy density. Pattern size decreased for lower laser beam power and greater scan speed, leading to a minimum pattern width of around 50nm at P in=1.2μW and V=12μm/s. Direct writing of an arbitrary pattern with a line width of about 150nm was demonstrated to verify the feasibility of this technique for nanomask fabrication. [Copyright &y& Elsevier]

The distance between tip and sample can be regulated using piezoelectric quartz fork glued with micro optic fiber probe. A biquadrate vibration equation for the fork–probe–sample system is established to theoretically analyze the relations of the electric current flow through fork versus tip–sample (T–S) distance (I–d). The I–d curve and the action distance for shear force are influenced by environmental humidity. The results reinforce the opinions in the earlier works by other researches that the physical origin of the shear force is due to a material filling the tip–sample gap. Furthermore, the intrinsic reasons for shear force damping between tip and sample have been confirmed and developed, i.e. the water and hydrocarbon coupled between optic fiber probe and sample due to the capillary cohesion force. [ABSTRACT FROM AUTHOR]

Summary Bent near-field optical probes for biological applications have been fabricated using a combination of a two-step chemical etching method and focused ion beam milling to create a well-defined aperture. The transmission efficiencies have been evaluated as a function of laser wavelength (λ) and aperture size (D ) for both large and small core fibres. The probe transmission behaviour follows a (D /λ)3 relationship. The double-etched probes are compared to pulled probes fabricated from highly GeO2 -doped dispersion compensating fibre and a standard single-mode optical fibre. The transmission efficiencies of both types of pulled probes are approximately two orders of magnitude lower than double-etched probes with similar aperture sizes. To demonstrate the utility of the various probes, their imaging performance has been evaluated for samples of polymer beads and phase-separated phospholipid monolayers of dipalmitoylphosphatidylcholine or cholesterol/phosphatidylcholine/sphingomyelin mixtures. Both pulled and double-etched probes are suitable for fluorescence imaging of polymer spheres. However, pulled probes are rapidly damaged at the higher input laser intensities required for fluorescence imaging of monolayer samples doped with < 1% of a fluorescent dye-labelled lipid. The images obtained with the double-etched probes show excellent spatial resolution and signal/noise, illustrating the potential of such probes for imaging of biological samples. [ABSTRACT FROM AUTHOR]

The article discusses the electroless nickel plating under continuous ultrasonic irradiation to fabricate a near-field probe whose metal coat decreases in thickness toward the tip. This study has described a size-dependent electroless plating method to fabricate a new type of probe with a locally decreasing thickness of metal and a tiny tip size for a combined high resolution shear-force and near-field optical microscope.