Analytical Study of Noise Spectral Density in Q-controlled Atomic Force Microscopy

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