Laser Absorption Spectroscopy Sample Cell Volume Reduction
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Solution Overview
Problem
Conventional spectroscopic sample cells have significant excess gas volumes that are not traversed by the radiation beam, leading to inefficient gas flow and measurement errors due to mechanical stability and calibration issues.
Innovation Solution
The design incorporates inserts and shaped surfaces within the sample cell to reduce the excess gas volume, with a maximum clearance distance for gas flow less than approximately 75 times the characteristic dimension of the beam, allowing for a more efficient gas path and improved measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sample cell design is used with large volume to ensure mechanical stability and calibration accuracy, then structural stability is improved, but excess gas volume increases leading to inefficient gas flow and measurement errors
Solution Approach 1:
The sample cell is divided into two distinct regions: a beam interaction volume where the radiation beam passes through for measurement, and a gas flow channel that allows efficient gas exchange. This segmentation enables the beam volume to be small for accurate measurement while the gas flow path ensures rapid replenishment of sample gas, resolving the contradiction between structural stability and excess gas volume.
Solution Approach 2:
The invention extracts the gas flow function from the beam interaction volume by providing a separate gas flow channel. This allows the beam path to be optimized for measurement accuracy with minimal volume, while gas flow efficiency is handled through the dedicated channel, eliminating the need for large excess gas volume in the measurement region.
2Stability of the object's composition
If larger sample cell volume is used to maintain pressure and temperature stability, then thermal stability is improved, but gas exchange time increases reducing response speed
Solution Approach 1:
The sample cell design segments the volume into a small beam interaction region for stable measurement conditions and a separate gas flow channel for rapid gas exchange. The small beam volume maintains pressure and temperature stability, while the dedicated gas flow path ensures quick replenishment of sample gas, resolving the contradiction between thermal stability and gas exchange speed.
Solution Approach 2:
A separate gas flow channel acts as an intermediary between the gas source and the beam interaction volume. This intermediary pathway allows rapid gas exchange without requiring the beam interaction volume to be large, thus maintaining both thermal stability and fast response time.
3Productivity
If sample cell dimensions are reduced to minimize excess gas volume, then gas flow efficiency is improved, but mechanical stability and calibration accuracy deteriorate
Solution Approach 1:
The invention segments the sample cell into a small beam interaction volume for efficient gas flow and a separate region for mechanical support and calibration references. This segmentation allows the measurement volume to be minimized for gas flow efficiency while maintaining adequate mechanical stability and calibration accuracy through the separate support structure.
Solution Approach 2:
The mechanical stability and calibration functions are extracted from the beam interaction volume and provided by separate structural elements. This allows the beam volume to be minimized for gas flow efficiency while the extracted mechanical support structures maintain calibration accuracy and structural stability.
4Ease of manufacture
If conventional sample cell design is used without volume reduction features, then ease of manufacture is improved, but measurement response time increases due to excessive gas volume
Solution Approach 1:
The sample cell is segmented into a compact beam interaction region and a gas flow channel, both of which can be manufactured using standard techniques. This segmentation achieves rapid gas exchange and improved response time while maintaining manufacturing simplicity through the use of conventional fabrication methods for the divided components.
Solution Approach 2:
The invention applies local quality optimization by providing volume reduction features specifically in the beam interaction region where excess volume causes measurement delays, while other regions maintain standard dimensions for ease of manufacture. This localized optimization improves response time without compromising overall manufacturing simplicity.
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 configuration minimizes the excess gas volume, enhancing gas exchange and measurement response times, allowing for faster equilibration to changes in gas composition and improved analytical accuracy.
Implementation Method 1
Spectroscopic analysis generally relies on detection and quantification of emission, absorption, or scattering of radiation by matter. In the case of gas-phase spectroscopy, the emission, absorption, or scattering of radiation occurs by individual molecules of one or more compounds present along a radiation path
Implementation Method 2
At least some of the radiation transmitted along this path can be absorbed or scattered, or other radiation can be emitted by the molecules in the radiation path. The wavelength of the absorbed, scattered, or emitted light generally is determined by the particular energy transition occurring to the molecules
Data Source
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AI summary
A sample cell can be designed to minimize excess gas volume. Described features can be advantageous in reducing an amount of gas required to flow through the sample cell during spectroscopic measurements, and in reducing a time (e.g. a total volume of gas) required to flush the cell between sampling events. In some examples, contours of the inners surfaces of the sample cell that contact the contained gas can be shaped, dimensioned, etc. such that a maximum clearance distance is provided between the inner surfaces at one or more locations. Systems, methods, and articles, etc. are described.