Active noise reduction has been accomplished in atomic force microscop
y by applying a high frequency, low amplitude vibration to the cantile
ver while it is in contact with a surface, The applied excitation (>20
0 kHz: similar to 1 nm) is acoustically coupled to the tip and dampens
the resonance Q factors of the system. The applied frequency is well
above the bandwidth of the acquisition system (50 kHz). We call this m
ode ''gamble mode'' or ''resonance contact.'' (C) 1996 American Vacuum
Society.