Spectrometer Noise Suppression via Skewed Detector Array
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Solution Overview
Problem
Two-dimensional detector arrays used in interferometer-based spectrometers suffer from row and column noise, which degrade the signal-to-noise ratio and dynamic range, especially when detecting interference patterns with intensity variations extending in one direction.
Innovation Solution
A method and apparatus that involves rotating the detector array to a non-zero skew angle relative to the interference fringes, allowing signals to be processed along aligned parallel or transverse lines to generate a one-dimensional output representing wavelength components, thereby reducing noise and enhancing spectral information extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-dimensional detector array is used to detect interference patterns, then the signal collection capability and potential signal-to-noise ratio are improved, but row and column noise are introduced that degrade the actual signal-to-noise ratio and dynamic range
Solution Approach 1:
The patent applies asymmetry by intentionally skewing the interference pattern at a non-zero angle relative to the detector array axes. This asymmetric orientation causes the signal to distribute across multiple rows and columns rather than aligning with noise-prone row or column structures, thereby reducing the impact of row and column noise on the measured signal
Solution Approach 2:
The patent transforms the problem from a one-dimensional signal extraction problem to a two-dimensional spatial frequency analysis problem. By treating the detector array output as a two-dimensional spatial spectrum and applying directional filtering or integration along the skewed signal direction, the method separates signal from noise in the spatial frequency domain, effectively suppressing row and column noise
2Quantity of substance
If the interference pattern width is spread across a two-dimensional detector array, then more signal can be collected potentially enhancing the signal-to-noise ratio, but the inherent row and column noise of the detector array increases
Solution Approach 1:
By skewing the interference pattern at a non-zero angle to the detector axes, the signal is distributed asymmetrically across the two-dimensional array. This prevents the signal from coinciding with the regular row and column noise structures, allowing more signal to be collected while minimizing the impact of detector noise
Solution Approach 2:
The patent introduces spatial frequency domain transformation as an intermediary step between signal collection and final processing. This intermediary representation allows for selective filtering of noise components while preserving the skewed signal, effectively separating desired signal from harmful noise
3Ease of operation
If signals are processed directly from a two-dimensional detector array without skewing, then processing is simpler, but row and column noise cannot be effectively suppressed
Solution Approach 1:
The patent applies preliminary action by pre-skewing the interference pattern at a non-zero angle before detection. This pre-processing step ensures that when signals are extracted, they naturally distribute across multiple detector rows and columns, automatically reducing correlation with row and column noise structures without requiring complex post-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 suppresses row and column noise, improving the signal-to-noise ratio and dynamic range by separating signal data from noise structures in the transformed image, allowing for more accurate spectral information retrieval.
Implementation Method 1
The beamsplitter 15 divides the beam into two portions and directs the two portions to the mirrors 21 and 22. The beam portions travel along similar cyclic paths but in opposite directions... when the two parts of the beams are recombined an interference pattern results
Implementation Method 2
In this arrangement the mirrors 21 and 22 are curved mirrors. The curved mirrors provide focussing of the two beam portions on the detector 30. A spatial interferometric signal is formed at the detector
Implementation Method 3
The detector 30 may be a pixel array which may be optimised for detecting wavelengths of electromagnetic radiation of interest, such as visible light or infra-red. Example detectors may be CCD or CMOS arrays
Data Source
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AI summary
A spectrometer for detecting one or more wavelength components of sample radiation is disclosed. The spectrometer comprises: a detector comprising a two- dimensional rectilinear array of pixels for generating signals representing an image based on collected sample radiation; one or more optical components arranged to form a spatial pattern based on spectral features of the sample radiation, the spatial pattern comprising a plurality of aligned substantially parallel fringes oriented at a non-zero skew angle to the two-dimensional rectilinear array; and an analyser arranged to receive the signals and provide an output related to the one or more wavelengths. The spectrometer suppresses column/row noise in the detector. Also disclosed is a method of suppressing noise when signals are extracted and processed from detector arrays.