Wideband digital frequency detector with subtraction-based phase comparator for frequency modulation atomic force microscopy

Wideband digital frequency detector with subtraction-based phase comparator for frequency modulation atomic force microscopy.

We have developed a wideband digital frequency detector for high-speed frequency modulation atomic force microscopy (FM-AFM). We used a subtraction-based phase comparator (PC) in a phase-locked loop circuit instead of a commonly used multiplication-based PC, which has enhanced the detection bandwidth to 100 kHz. The quantitative analysis of the noise performance revealed that the internal noise...

Wideband phase-locked loop circuit with real-time phase correction for frequency modulation atomic force microscopy.

We have developed a wideband phase-locked loop (PLL) circuit with real-time phase correction for high-speed and accurate force measurements by frequency modulation atomic force microscopy (FM-AFM) in liquid. A high-speed operation of FM-AFM requires the use of a high frequency cantilever which, however, increases frequency-dependent phase delay caused by the signal delay within the cantilever e...

Analog frequency modulation detector for dynamic force microscopy

A new analog frequency modulation ~FM! detector ~demodulator! for dynamic force microscopy ~DFM! is presented. The detector is designed for DFM by utilizing the FM detection method where the resonance frequency shift of the force sensor is kept constant to regulate the distance between a tip and a sample surface. The FM detector employs a phase-locked loop ~PLL! circuit using a voltage-controll...

Self-oscillating mode for frequency modulation noncontact atomic force microscopy

Physical interpretation of frequency-modulation atomic force microscopy

Frequency modulation atomic force microscopy is a method for imaging the surface of metals, semiconductors and insulators in ultrahigh vacuum with true atomic resolution. The imaging signal in this technique is the frequency shift D f of an oscillating cantilever with eigenfrequency f 0 , spring constant k and amplitude A, which is subject to tip-sample forces Fts . Here, we present analytical ...