Digital Phase Measurement System for AFM
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Solution Overview
Problem
Current phase measurement techniques in atomic force microscopy and other devices are limited by speed and accuracy, particularly in dynamic modes like PM-AFM, due to inefficiencies in existing phase measurement circuits, which hinder high-speed and precise imaging.
Innovation Solution
A method involving a digital clock signal of multiple frequency, generating digital reference signals, and point-to-point multiplication with the input signal to achieve accurate phase measurement without cyclical errors, allowing for fast and precise phase shift estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional phase measurement circuits are used in atomic force microscopy, then the measurement can be performed, but the speed and accuracy are limited
Solution Approach 1:
The patent replaces traditional analog phase measurement circuits with a digital signal processing system. The input signal is digitized and processed using digital multiplication and accumulation operations to calculate phase shift, eliminating the limitations of analog circuits and achieving both high speed and high precision phase measurement
Solution Approach 2:
The patent changes the measurement approach by using digital signal processing parameters (sampling frequency, multiplication factors, accumulation counts) instead of analog circuit parameters. By adjusting the number of accumulation operations N, the system can optimize between speed and precision based on application requirements
2Productivity
If phase measurement is performed in dynamic modes like PM-AFM, then imaging capability is enhanced, but existing circuit inefficiencies hinder high-speed and precise imaging
Solution Approach 1:
The patent substitutes analog phase detection circuits with a digital signal processing system that performs point-by-point multiplication of the input signal with reference signals followed by accumulation. This digital approach enables high-speed imaging in dynamic modes like PM-AFM while maintaining precise phase measurement capability
Solution Approach 2:
The patent implements continuous phase measurement by processing each sampled point of the input signal through multiplication and accumulation operations. This continuous digital processing ensures uninterrupted phase information is available for high-speed dynamic imaging applications
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables fast, precise, and noise-resistant phase measurement with improved signal-to-noise ratio, suitable for high-frequency applications like atomic force microscopy and phase-locked loops.
Implementation Method 1
convert the first digital reference signal analogically, so as to obtain a first analog reference signal
Implementation Method 2
sample the analog input signal according to the frequency N fo of the digital clock signal, so as to obtain a digital input signal
Data Source
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AI summary
The invention relates to a method (METH) for measuring a phase shift ϕ induced by an analog phase-shifting (PS) system operating at a frequency fo, comprising the following steps: a) from the frequency fo and an integer N given as parameters, generate a digital clock signal (Shn) of frequency N.fo, b) from the digital clock signal (Shn), generate a first digital reference signal (Sr1n) of the form cos(2π.fo.t), sampled according to the frequency N.fo of the digital clock signal (Shn), then: - convert the first digital reference signal (Sr1n) analogically, so as to obtain a first analog reference signal (Sr1a) - send said first analog reference signal (Sr1a) to the phase-shifting (PS) system - receive from the phase-shifting (PS) system an analog input signal (Sga) of the form A.cos(2π.fo.t+ϕ), where A is a proportionality factor - sample the analog input signal (Sga) according to frequency N.fo of the digital clock signal (Shn), so as to obtain a digital input signal (Sgn) - multiply point by point the first digital reference signal (Sr1n) and the digital input signal (Sgn), to provide a first digital product signal (SP1n) - sum N values of the first product signal (SP1n), in order to obtain a first sum (S1) of the form (NA/2)cos(ϕ) c) calculate the value of the phase shift ϕ by means of the first sum (S1).