Journal of the Korean Physical Society, Vol. 72, No. 3, February 2018, pp. 384∼389
Manhee Lee, Sangmin An, Wonho Jhe
Q-controlled atomic force microscopy utilizes an oscillating probe with an adjustable quality
factor, which is done by adding a variable damping interaction to the probe. While the Q-control
can enhance the probe sensitivity by increasing the Q-factor, the applied interaction increases the
noise of the probe motion as well. Thus, the signal-to-noise ratio (SNR) associated with the probe
sensitivity varies accordingly. Here, we analytically derive the noise spectral density of the tip
motion, and theoretically investigate the SNR in Q-controlled atomic force microscopy. We show
that both the overall tip-motion signal and the noise monotonically increase with the effective Qfactor
under control, whereas the SNR exhibits a global minimum near the original Q value and
asymptotically scales as the square root of the effective Q-factor. Therefore, in general, the Qcontrol
technique can be used to alter the quality factor, the magnitudes of signal and noise, and
the probe sensitivity in amplitude-modulation atomic force microscopy
https://link.springer.com/article/10.3938/jkps.72.384