An AFM approach using calibrated side-sensitive tip geometry and position control to measure steep or reentrant features. A flared tip can reach surfaces that an ordinary tapered probe cannot; calibration must account for its effective width.^[ref]

A distortion caused by the finite shape or multiple contact points of a scanning tip. For a single-valued sample height $h$ and a tip profile $t$ measured upward from its apex, nonpenetration requires the indicated apex height to satisfy $z(x)\ge h(u)-t(u-x)$ for every $u$. The ideal accessible envelope is consequently $z(x)={\max }_u[h(u)-t(u-x)]$. This geometric operation is distinct from an ordinary linear convolution and from feedback lag.

A contact measurement of electrically driven local surface displacement, detected by cantilever bending or torsion and often demodulated by a lock-in amplifier. Electrostatic and contact-mechanical cross-talk must be separated from converse piezoelectric effect response.

Measurement of lateral tip–surface forces from torsion of an atomic-force-microscope cantilever.

Signals acquired in the two opposite scan directions, registered to common laboratory coordinates.

An instability in a compliant force probe when the attractive force gradient exceeds the restoring stiffness of the cantilever. The tip then jumps from a noncontact branch into contact; the missing branch cannot be followed quasistatically with that stiffness.

A force-curve mapping mode that controls the peak repulsive normal force during repeated low-frequency tip-surface contacts. Calibrated force curves provide topography and spatial maps of adhesion, deformation, modulus and dissipated energy. Mechanical-property accuracy depends on tip geometry, cantilever calibration and the contact model.

A curved height background caused by coupling of lateral scanner displacement to vertical motion, particularly the arc followed by a bending piezoelectric tube. A real curved specimen and instrumental bow cannot be separated from one height image without additional information.

Subtraction of fitted background planes or polynomials from an AFM height image. This removes tilt or scanner curvature only to the extent that the chosen fit represents the instrument rather than real specimen topography.

A sharp tip carried by a calibrated AFM cantilever and brought near a surface to sense forces. Tip geometry and contamination influence both lateral resolution and mechanical or electrical measurements.

A measured tip–sample force versus displacement or separation during approach and withdrawal. Contact deformation, adhesion and instrumental compliance must be separated before extracting a material property.

Geometrical broadening of a surface feature by the finite shape of an AFM probe. The same geometry can narrow the accessible part of a surface depression. The measured height envelope is more precisely a morphological dilation than an ordinary linear convolution. Repeated identical particle outlines can be tip images; inaccessible sidewalls prevent a unique inverse reconstruction.

A scan distortion caused by the finite bandwidth or instability of the height-control loop. Streaks, lag and ringing can be diagnosed by changing speed, controller gains and scan direction and comparing trace with retrace.

Current-sensitive atomic force microscopy using a conducting tip and a low-current amplifier. A steady conductivity map requires a complete electrical path through the contacted specimen region, even when force-based topography can be recorded without it.

Mapping of local mechanical response from calibrated AFM force curves. Deformation, adhesion and a model-dependent contact elastic modulus can be separated more directly than by interpreting oscillation phase alone. Tip radius, indentation depth, loading rate and substrate response constrain quantitative interpretation.

Scanning-probe mapping of local capacitance response. Conventional semiconductor dopant profiling measures a bias-modulated $dC/dV$ signal involving an insulating layer and a changing semiconductor depletion region; an electrically isolated conducting flake on glass is not automatically that device geometry.

An apparent image change caused by alteration of the effective probe apex during acquisition. A shifted height baseline may be corrected using a suitable reference, but changed geometric access, duplicated features and lost data are not generally repaired by AFM image flattening.

A force-microscopy mode keeping the probe in contact while monitoring cantilever deflection. Constant-deflection feedback records the vertical actuator motion needed to maintain an approximate normal-force setpoint; finite probe geometry and specimen deformation still affect the image.

Mapping electrical current through a conducting probe contact while recording topography. Local current depends on bias, contact geometry, surface layers and contact resistance as well as the specimen's electrical response.

A two-pass scan method recording topography first, then retracing it at an offset height to measure a longer-range interaction with reduced contact contributions. It is a Bruker mode name.^[ref]