Optical Signal Processing for Time-Decay Spectral Analysis
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Solution Overview
Problem
Current spectral analysis systems face challenges in rapidly extracting information from complex absorption data, particularly in real-time monitoring of contaminated samples, due to the presence of contaminants that absorb light at the same frequency as the species of interest.
Innovation Solution
A digital detection scheme that involves mixing a time-decay signal with a local oscillator signal to generate a Fourier transformed signal, allowing for the determination of spectral content by analyzing the magnitude of frequency components, which can be used to quickly extract absorption information from contaminated samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spectral analysis is performed on contaminated samples by measuring absorbance over a range of wavelengths, then absorption information can be extracted, but the analysis speed is slow
Solution Approach 1:
The patent applies periodic action by modulating the light source at a specific frequency and using lock-in detection to periodically sample the absorbance signal. This allows the system to extract spectral information through frequency-domain analysis rather than scanning through all wavelengths sequentially, significantly increasing analysis speed while maintaining measurement precision for identifying chemical species in contaminated samples.
Solution Approach 2:
The patent introduces an intermediary approach by using a modulated light source and lock-in amplifier as intermediate components between the light source and detector. The lock-in amplifier acts as an intermediary that selectively detects signals at the modulation frequency, filtering out noise and enabling rapid extraction of absorption information without requiring full spectral scanning.
2Reliability
If contaminants are present that absorb light at the same frequency as the species of interest, then real-time spectral analysis becomes difficult, but measuring at a single frequency is insufficient
Solution Approach 1:
The patent applies segmentation by dividing the spectral analysis into discrete frequency components through modular detection. Instead of analyzing the entire spectrum at once, the system segments the signal into frequency components using lock-in detection at specific modulation frequencies. This allows reliable identification of species even in contaminated samples by analyzing individual frequency segments separately.
Solution Approach 2:
The patent utilizes parameter changes by modulating the light source frequency and detecting absorbance at different frequency points. By changing the modulation frequency and analyzing the response at multiple frequencies, the system can distinguish between the species of interest and contaminants with overlapping absorption features, improving reliability without requiring overly complex measurement systems.
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 method enables real-time analysis of absorbance signals, significantly speeding up the detection process and improving the signal-to-noise ratio by filtering out noise sources not coinciding with the local oscillator frequencies, allowing for precise determination of the decay constant and absorption spectra.
Implementation Method 1
in a mixer, mixing the time-decay signal with a local oscillator signal generated by a local oscillator generator, resulting in a mixed signal
Implementation Method 2
from which a Fourier transformed time-decay signal is generated comprising a fundamental transformed time decay signal at the fundamental frequency of the local oscillator signal and a plurality of harmonic transformed time-decay signals at a plurality of harmonic frequencies of the fundamental frequency
Data Source
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Figure 2A
Figure 2B
AI summary
Systems and methods for analysing a time-domain signal are described. The method comprising: in a mixer (150), mixing the time-decay signal (115) with a local oscillator signal (122) generated by a local oscillator (120), resulting in a mixed signal from which a Fourier transformed time-decay signal is generated comprising a fundamental transformed time decay signal at the fundamental frequency of the local oscillator signal (122) and a plurality of transformed time-decay signals at a plurality of frequencies; and determining the magnitude of each of the transformed time-decay signals at the fundamental frequency and at a frequency other than the fundamental frequency.