Collimated Infrared Gas Sensor Beam Splitter Design
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Solution Overview
Problem
Existing dual-beam non-dispersive infrared (NDIR) gas sensors face challenges in measurement accuracy due to the use of non-collimated light and the complexity of construction, which results in significant IR energy loss and increased component complexity, particularly with the use of a dividing wall and waveguides.
Innovation Solution
A gas measurement sensor utilizing a collimated infrared light source and a beam splitter that employs specular reflection to split the light into well-collimated reference and measurement beams, eliminating the need for waveguides and simplifying the construction by using a prism or pyramid coated with reflective materials, allowing for precise alignment and easy detector replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a dividing wall is used to split non-collimated light between two tubes, then the light can be distributed to form measurement and reference pathways, but the measurement accuracy deteriorates due to difficulty in precisely controlling the proportion of IR light directed along each tube
Solution Approach 1:
The patent changes the state of the light from non-collimated to collimated before the beam splitter. This parameter change enables precise control of light distribution proportions, resolving the contradiction between ease of operation and measurement precision.
2Loss of energy
If waveguides are provided on the sidewalls of tubes to guide IR light, then transmission losses from light absorption by sidewalls are reduced, but the construction becomes significantly more complex and expensive
Solution Approach 1:
The patent extracts and eliminates the waveguide components from the system. By using a collimated light source and proper beam splitter geometry, the invention achieves low energy loss without requiring complex waveguide structures, thus resolving the contradiction between energy loss reduction and construction complexity.
Solution Approach 2:
The patent replaces the mechanical waveguide system with an optical solution using collimated light and reflective beam splitting. This substitution eliminates the need for physical waveguide structures while maintaining or improving optical performance.
3Device complexity
If waveguides and dividing walls are used to split light, then measurement pathways can be formed, but significant IR energy is lost
Solution Approach 1:
The patent removes the waveguide components that cause energy loss. By using a collimated light source and beam splitter, the system achieves the necessary light distribution with minimal components, eliminating significant IR energy loss while reducing component quantity.
4Device complexity
If a collimated infrared light source is used with a beam splitter, then IR energy loss is minimized and construction is simplified, but the device complexity increases due to the need for precise beam splitting and alignment
Solution Approach 1:
The patent performs preliminary collimation of the infrared light source before it reaches the beam splitter. This preliminary action ensures that the light is properly prepared for precise beam splitting and detection, reducing the need for complex alignment procedures during assembly.
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 minimizes IR energy loss, enhances measurement accuracy, and simplifies the sensor construction, reducing costs and complexity while maintaining high sensitivity for gas concentration measurements.
Implementation Method 1
said beam splitter is arranged to reflect a first portion of said infrared light impinging thereon by specular reflection so as to form said reference beam, and to reflect a second portion of said infrared light by specular reflection so as to form said measurement beam
Implementation Method 2
a source of substantially collimated infrared light, arranged to direct said infrared light into said measurement chamber
Implementation Method 3
The beam splitter is arranged in the measurement chamber such that the length of the pathway of the measurement beam through said chamber is longer than that of the reference beam through said chamber
Implementation Method 4
infrared gas measurement sensor exploiting absorption of infrared light by one or more gas specie(s) of interest so as to determine a concentration thereof
Data Source
AI summary
Gas measurement sensor including: a measurement chamber including an inlet and outlet for a gaseous sample to be measured; an infrared light source producing substantially collimated infrared light and to direct the infrared light into the measurement chamber; a beam splitter situated in the measurement chamber so as to receive the infrared light and to split the infrared light into a reference beam and a measurement beam such that the measurement beam has a longer pathway through the measurement chamber than the reference beam; a reference infrared detector arranged to receive the reference beam; and a measurement infrared detector arranged to receive the measurement beam. The beam splitter is arranged to reflect a first portion of the infrared light by specular reflection so as to form the reference beam, and to reflect a second portion of the infrared light by specular reflection so as to form the measurement beam.