Interference Spectrophotometer Speed Variation False Peak Elimination
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Solution Overview
Problem
In Fourier transform spectrophotometers, periodic noise can cause false peaks in spectra due to its similarity in frequency with signal components, making it difficult to distinguish from actual sample frequencies, leading to inaccurate spectral data.
Innovation Solution
A two-beam interferometer with a movable mirror that changes speed during each operation cycle, allowing for the detection of intensity signals at varying optical path length differences, and an information extractor to identify and separate speed-dependent noise, which is then corrected to remove false peaks from the spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the movable mirror moves at a fixed speed to generate interference light, then the measurement timing can be controlled at regular intervals, but periodic noise appears in the measurement signal causing false peaks in the spectrum
Solution Approach 1:
The movable mirror is made to reciprocally move multiple times to generate a series of measurement signals. By analyzing the periodicity and timing of these signals, the system can identify and eliminate periodic noise that appears at fixed intervals, thereby improving spectral data accuracy while maintaining controlled measurement timing
Solution Approach 2:
The system measures the intensity of interference light at regular intervals during reciprocal motion of the movable mirror, and uses this feedback information to identify periodic noise patterns. The measured signals are processed to distinguish between actual spectral features and periodic noise, allowing for correction of false peaks in the final spectrum
2Object-affected harmful factors
If the movable mirror moves at varying speeds to eliminate periodic noise, then false peaks are removed from spectra, but the measurement timing control becomes more complex
Solution Approach 1:
Instead of using complex variable speed control, the system employs simple reciprocational motion of the movable mirror at constant speed. The periodic nature of this motion, combined with signal processing analysis, enables identification and removal of periodic noise causing false peaks, thereby eliminating the need for complex variable speed control mechanisms
Solution Approach 2:
The system creates multiple copies of the measurement signal through repeated reciprocal motions of the movable mirror. By comparing these copied signals and analyzing their consistency, the system can identify periodic noise patterns and remove false peaks without requiring complex speed variation, thus simplifying the control system
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 eliminates false peaks caused by periodic noise, resulting in more accurate and reliable spectral data by differentiating between signal and noise based on moving speed changes.
Implementation Method 1
a beam splitter configured to divide multiwavelength light into two light beams
Implementation Method 2
a movable mirror and a fixed mirror configured to respectively reflect the two light beams back to the beam splitter
Implementation Method 3
produce interference light from multiwavelength light... generate infrared interference light whose amplitude (intensity) changes (i.e. the so-called 'interferogram')
Data Source
AI summary
In a two-beam interferometer, the moving speed of a movable mirror for producing interference light to generate a spectrum is changed at each completion of an operation cycle during which a reciprocal motion or one-way motion of the movable mirror is performed one or more times. Intensity signals of the interference light are obtained by a plurality of detection operations, where each detecting operation includes a series of detecting operations corresponding to the reciprocal motion or one-way motion of the movable mirror performed one or more times. A piece of information which changes depending on the moving speed of the movable mirror is extracted from the intensity signals obtained by the detection operations. This speed-dependent information corresponds to periodic noise superposed on the intensity signals. Accordingly, a false peak which would otherwise appear on the spectrum due to the periodic noise can be eliminated by removing the speed-dependent information.