Fourier Spectrophotometer Noise Removal via Inverted Interferograms
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Solution Overview
Problem
In Fourier spectrophotometers, low signal-to-noise ratios in light reception signals lead to decreased analysis accuracy, particularly when samples with rapidly changing optical characteristics are analyzed, resulting in wasted light and reduced effectiveness in obtaining high-quality spectra.
Innovation Solution
A Fourier spectrophotometer design that includes an interferometer generating inverted interferograms, a multiplexing optical system to combine these interferograms, and a demultiplexing system to separate them, along with a signal processing device that removes noise by subtracting signals from the light receiver, enhancing the S/N ratio and maintaining high analysis accuracy without light waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Fourier spectrophotometer is used, then device complexity is low, but analysis accuracy decreases when samples have temporal fluctuations in optical characteristics
Solution Approach 1:
The patent divides the interferogram into multiple wavelength bands (first wavelength band and second wavelength band) and processes them separately. The first wavelength band is used for obtaining the spectrum of the sample, while the second wavelength band is used for noise removal, allowing each segment to serve a specific function and improve overall analysis accuracy
Solution Approach 2:
The patent introduces a noise removal unit that acts as an intermediary component. This unit uses the wavelength component from the second wavelength band as a mediator to remove noise from the first wavelength band signal, thereby improving the signal-to-noise ratio without directly modifying the sample analysis path
2Measurement precision
If light is not effectively utilized, then device complexity remains low, but S/N ratio of light reception signal decreases
Solution Approach 1:
The patent makes the interferogram serve multiple functions: the first wavelength band provides the spectrum information for sample analysis, while the second wavelength band provides noise information for signal processing. This multi-functionality ensures that light energy is not wasted but rather utilized for both analysis and noise removal purposes
Solution Approach 2:
The patent recovers useful information from the second wavelength band that would otherwise be discarded. Instead of ignoring the second wavelength band, the system recovers noise characteristics from it and uses these to improve the quality of the first wavelength band signal through noise removal processing
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 effectively utilizes light for analysis, achieving high accuracy even with samples exhibiting temporal fluctuations in optical characteristics by improving the S/N ratio and minimizing light waste, thereby enhancing the overall analysis quality.
Implementation Method 1
an interferometer (20) configured to obtain a first interferogram (L11) and a second interferogram (L12) whose intensity distributions are inverted from each other as interferograms (L2) from the light emitted from the light source
Implementation Method 2
a multiplexing optical system (30) configured to multiplex the first interferogram with the second interferogram to irradiate the sample with a resultant interferogram
Implementation Method 3
a demultiplexing optical system (40) configured to demultiplex the first interferogram (L41) and the second interferogram (L42) contained in the light (L3) passing through the sample
Implementation Method 4
a light receiver (50) configured to output a first light reception signal (S1) obtained by receiving the demultiplexed first interferogram and a second light reception signal (S2) obtained by receiving the demultiplexed second interferogram
Implementation Method 5
a Fourier transformer (62) configured to perform Fourier transform processing on a signal indicating the difference obtained by the noise remover to obtain the spectrum of the wavelength component in the analysis wavelength band
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A Fourier spectrophotometer includes: a light source; an interferometer configured to obtain first and second interferograms whose intensity distributions are inverted from each other from the light emitted from light source; a multiplexing optical system configured to multiplex the first and second interferograms to irradiate the sample with a resultant interferogram; a demultiplexing optical system configured to demultiplex the first and second interferograms contained in the light passing through the sample; a light receiver configured to output a first light reception signal obtained by receiving the demultiplexed first interferogram and a second light reception signal obtained by receiving the demultiplexed second interferogram; and a signal processing device configured to perform processing for obtaining a noise-removed spectrum of the wavelength component in the analysis wavelength band by using the first and second light reception signals.