Slitless Spectrographic Sensor for Combustion Gas Analysis
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Solution Overview
Problem
Existing methods for measuring combustion gas temperature and species concentration, such as emission spectroscopy, suffer from energy loss due to the use of standard optical slits and lack the capability for high-speed, high-resolution analysis necessary for real-time monitoring in internal combustion engines.
Innovation Solution
The implementation of a high-speed spectrographic sensor system using absorption spectroscopy with a spatial heterodyne spectroscope and a light guide, such as fiber optics, that eliminates the need for optical slits, allowing for real-time multi-spectral measurements of combustion gases with automatic temperature and water concentration analysis, and employing a Fourier spectroscope for fast and accurate data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard optical slit is used in the spectrometer, then the spectral resolution is improved, but the light energy loss increases significantly
Solution Approach 1:
The patent removes the optical slit from the spectrometer system entirely, replacing it with a slitless imaging approach that uses a curved focal plane detector to achieve spectral resolution without the energy loss associated with traditional slits
Solution Approach 2:
The patent transitions from a one-dimensional slit-based spectral dispersion to a two-dimensional curved focal plane where spatial position and spectral information are simultaneously encoded, eliminating the need for physical slits while maintaining spectral resolution
2Measurement precision
If a slit spectrometer is used, then the spectral analysis capability is achieved, but the measurement speed is reduced due to energy loss
Solution Approach 1:
By removing the optical slit, the system eliminates the primary source of light energy loss that limited measurement speed, enabling faster photon collection and higher temporal resolution spectral measurements
Solution Approach 2:
The patent replaces the mechanical slit aperture with an optical design using curved focal planes and strategic mirror placements, eliminating mechanical constraints on measurement speed while maintaining spectral analysis capability
3Loss of energy
If the aperture size is increased to improve light collection, then the energy efficiency is improved, but the spectral resolution deteriorates in traditional slit spectrometers
Solution Approach 1:
The patent uses a curved focal plane detector that separates spatial and spectral dimensions, allowing large aperture light collection while maintaining spectral resolution through the curved geometry that focuses different wavelengths to different spatial positions
Solution Approach 2:
The curved focal plane effectively segments the incoming light into distinct spectral components across its surface, allowing simultaneous collection of multiple wavelengths with high efficiency while maintaining the ability to resolve individual spectral features
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 enables high-resolution, real-time measurement of combustion gas parameters with improved energy efficiency and temporal resolution, capturing dynamic processes with accuracy and precision, particularly in the vicinity of the spark plug within an internal combustion engine.
Implementation Method 1
using a light guide that may be as small as a fiber optic
Implementation Method 2
measurement of combustion gas temperature and species concentration using absorption spectroscopy techniques
Implementation Method 3
The sensor system may be a spatial heterodyne spectroscope receiving the light from the light guide
Implementation Method 4
employing a Fourier spectroscope for fast and accurate data processing
Data Source
Figure 1~2
Figure 3~5
AI summary
A high-speed absorption spectrographic system (10) employs a slit-less spectroscope (42, 71) to obtain high-resolution, high-speed spectrographic data of combustion gases in an internal combustion engine allowing precise measurement of gas parameters including temperature and species concentration.