Probe Landing Lab — force, contact resistance and the window

One slider: landing force. The curve shows contact resistance falling off its cliff onto its floor — bounded by an instability band on the left and a damage boundary on the right. Land mid-window and even thermal drift cannot pull you out.

Model honesty: the curve is an illustrative constriction-resistance construction, R_c(F) = R_∞ + R₀/(F/F₀)^0.7 — resistance falling steeply as load recruits more asperity contact area, in the spirit of rough-surface contact mechanics — with an instability band below F = 12 (too few asperities: readings wander) and a damage boundary above F = 78 (tip begins editing the sample), both placed for teaching rather than any real tip–sample pair. The drift button applies an illustrative signed offset of −15: real thermal drift may increase or decrease contact force and may also move the probe laterally, depending on the materials and mechanical geometry of the whole chain — the fixed sign here is a teaching scenario, not a rule. Real windows must be found experimentally per tip radius, sample hardness and film thickness; force and resistance here are arbitrary teaching units, not data for any real system.