FPGA Numerical Homodyne Evaluation for Scanning Microscope Signal Analysis
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Solution Overview
Problem
Current scanning microscopy methods face challenges in accurately determining the amplitude and phase of selected frequency components in measurement signals without requiring complex measurement methods, particularly in noisy environments with power-modulated light sources.
Innovation Solution
A method utilizing a numerical homodyne evaluation with oversampling and phase-shifted reference signals, implemented in an FPGA, allows for the determination of amplitude and phase of frequency components in measurement signals from scanning microscopes, enabling efficient evaluation without external lock-in amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external lock-in amplifiers or complex measurement methods are used to determine amplitude and phase of frequency components, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the lock-in amplification functionality from external dedicated hardware devices and implements it within the existing FPGA-based control unit of the scanning microscope. This extraction eliminates the need for separate external lock-in amplifiers while maintaining the precise amplitude and phase measurement capabilities, directly resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The control unit of the scanning microscope is designed to perform multiple functions: it controls the scanning beam, processes image data, and now also performs lock-in amplification for frequency component analysis. By making the control unit universal and multi-functional, the patent eliminates the need for dedicated external measurement devices, reducing overall system complexity while maintaining measurement precision
2Loss of information
If power-modulated light sources are used in scanning microscopy, then information about fluorescence lifetime and sample properties can be obtained, but noise in the measurement signal increases
Solution Approach 1:
The patent employs periodic modulation of the light source power at specific frequencies and uses synchronous detection (lock-in amplification) to extract signals at these modulation frequencies. By using periodic action and frequency-domain separation, the method distinguishes the modulated signal from background noise, allowing fluorescence lifetime information to be obtained while suppressing noise interference
Solution Approach 2:
The patent converts the potentially harmful effect of noise in power-modulated measurements into a benefit by using the modulation frequency as a signature. The lock-in amplification technique detects signals specifically at the modulation frequency and its harmonics, effectively converting the noisy environment into an opportunity for frequency-selective signal extraction that enhances rather than degrades measurement quality
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 simplifies the evaluation of frequency components, improves accuracy, and reduces noise in scanning microscopy by using digital signal processing to determine amplitude and phase, particularly beneficial for power-modulated light sources, enhancing image quality and fluorescence lifetime analysis.
Implementation Method 1
the power of the light coming from the object is detected by a detection device, wherein the detection device generates a detection signal dependent on the detected light power
Implementation Method 2
the excitation light beam can be power modulated according to a modulation function, e.g. sine, square, etc.
Data Source
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Figure 3a~3b
AI summary
The invention relates to a method and a computer unit for determining the amplitude and/or phase of a selected frequency component in a detected measurement signal, wherein an object is illuminated with light that is power-modulated according to a modulation signal having at least one frequency component, wherein a measurement signal is sampled with a sampling rate corresponding to at least four times the frequency of the selected frequency component, wherein each measurement value is multiplied by a value of a first and a second reference signal available at the respective measuring time in order to obtain a respective first and second product value for each measurement value, wherein the first reference signal has the selected frequency component and the second reference signal is phase-shifted by 90° relative to the first reference signal, wherein the first and the second product values are added up in order to obtain a first and a second product total value, from which the amplitude and/or the phase of the measurement signal are determined.