Planar Golay Cell With Wavelength Selective Absorber
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Solution Overview
Problem
Golay cells used in non-dispersive infrared (NDIR) gas detection face challenges in achieving high spectral correlation with target gases, requiring thicker gas layers for absorption, which increases heat capacity and reduces sensitivity, and are difficult to implement in compact designs due to wavelength non-selectivity and sensitivity to light angle.
Innovation Solution
A planar Golay cell with a wavelength selective absorber and a gas cavity filled with gases of specific heat and thermal conductivity characteristics, allowing for compact, spectrally selective detection of target gases by measuring pressure changes caused by absorbed radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gas absorber is used to achieve spectral correlation with target gases, then spectral selectivity is improved, but the required thicker gas layer increases heat capacity and reduces sensitivity
Solution Approach 1:
The patent introduces a wavelength selective absorber with specific absorption characteristics that matches the target gas spectrum. This absorber is placed within the gas cavity to provide localized spectral filtering, allowing the gas layer to remain thin while achieving the required spectral selectivity through the absorber's tailored optical properties.
Solution Approach 2:
The detector combines a gas filling (for general absorption) with a wavelength selective absorber (for spectral filtering) to create a composite absorption system. This composite structure enables spectral correlation with target gases while maintaining a thin gas layer, thereby reducing heat capacity and improving sensitivity compared to using a thick gas layer alone.
2Measurement precision
If a membrane absorber with external filter is used to provide spectral selectivity, then spectral correlation is improved, but cost increases and angle sensitivity problems occur
Solution Approach 1:
The patent merges the absorption and spectral filtering functions into a single integrated wavelength selective absorber component. This eliminates the need for separate external filters and reduces the system to a planar configuration, thereby reducing cost, simplifying structure, and eliminating angle sensitivity issues associated with external filters.
Solution Approach 2:
The wavelength selective absorber is designed with specific optical parameters (absorption spectrum, thickness, material composition) that are optimized for the target gas detection. By changing and optimizing these parameters, the absorber provides spectral selectivity without requiring external filters, thereby reducing device complexity and eliminating angle sensitivity.
3Measurement precision
If a gas absorber is used to achieve sufficient absorption, then spectral selectivity is improved, but a longer optical path length is required which conflicts with compact design requirements
Solution Approach 1:
The wavelength selective absorber provides localized spectral filtering within the gas cavity, enabling sufficient absorption efficiency in a short optical path. The absorber's tailored absorption characteristics compensate for the short path length, allowing compact design while maintaining detection precision.
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
Enables accurate detection of specific gases with reduced interference from ambient gases, achieving high sensitivity and compact form factors, allowing for multiple cells to be stacked and used in various applications.
Implementation Method 1
a wavelength selective absorber having a predetermined absorption spectral range
Implementation Method 2
converting absorbed optic radiation into heat causing the absorbing material to expand, resulting in a pressure rise that can then be detected
Implementation Method 3
converting absorbed optic radiation into heat causing the absorbing material to expand, resulting in a pressure rise that can then be detected
Implementation Method 4
absorbing at least a portion of the radiative power by the wavelength selective absorber or the gas within the gas cavity
Data Source
AI summary
Embodiments relate generally to electromagnetic radiation detector devices, systems, and methods using a planar Golay cell. One device includes a cell body forming a cavity therein, wherein the cavity includes a wavelength selective absorber having a predetermined absorption spectral range and the cavity is filled with a gas and a pressure sensing element fluidly connected to the cavity to measure a change in pressure within the cavity. One device may include a plurality of planar Golay cells, wherein the cell bodies of the Golay cells are stacked against one another, wherein the pressure sensing elements of the Golay cells are located adjacent to the stacked sides of the cell bodies, and wherein radiation from a single light source is directed through the plurality of Golay cells.