Variable Geometry Optical Gas Detector with Folded IR Path
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Solution Overview
Problem
Conventional non-dispersive optical gas detectors are cumbersome and inflexible, with fixed optical paths that are not adaptable to different types of gases, leading to reduced accuracy and increased dimensions, which limits their use in compact applications and reduces sensitivity.
Innovation Solution
A variable geometry optical gas detector with a cup-shaped body and disc-shaped lid, featuring interchangeable reflector elements that allow the optical path to be configured based on the gas type, enabling adjustable length and orientation of the electromagnetic radiation path for enhanced sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical path length is increased to improve sensitivity and accuracy, then the detector dimensions increase, making it cumbersome and unsuitable for compact applications
Solution Approach 1:
The patent transforms the optical path from a straight linear configuration to a folded multi-dimensional path using reflective surfaces. The optical path enters through a first wall, reflects off the opposite wall, and exits through a third wall, creating a three-dimensional folded path that achieves extended optical length within a compact footprint, resolving the contradiction between long optical path and small detector volume
Solution Approach 2:
The patent employs curved reflective surfaces (cylindrical or conical surfaces) instead of flat surfaces to guide the optical path. These curved surfaces enable the optical beam to follow a extended path through the gas sample while maintaining a compact detector structure, allowing the optical path to bend and fold within limited space, thus achieving both long optical path length and compact dimensions
2Ease of manufacture
If the optical path geometry is fixed to simplify manufacturing, then the detector cannot be adapted to detect different types of gases with varying absorption characteristics
Solution Approach 1:
The patent introduces variable geometric parameters (optical path length, reflection angles, wall spacing) that can be adjusted based on the specific gas detection requirements. By making the optical path geometry adaptable rather than fixed, the detector can be optimized for different gas types with varying absorption coefficients and spectral characteristics, achieving versatility while maintaining manufacturing feasibility through standardized modular components
Solution Approach 2:
The patent enables adaptation to different gas types by changing geometric parameters of the optical path, such as the length of the optical path, the angle of reflection, and the spacing between reflective walls. These parameter adjustments allow the detector to be tuned for optimal sensitivity to specific gases without requiring fundamental redesign, balancing manufacturing simplicity with adaptability
3Loss of time
If the distance for gas diffusion to reach the optical path is minimized to reduce detection time, then the optical path length must be shortened, reducing sensitivity
Solution Approach 1:
The patent uses a folded optical path configuration that enters through one wall, reflects off opposite walls, and exits through another wall, creating an extended optical path within a compact volume. This multi-dimensional path arrangement allows gas to diffuse a short distance to reach the optical path while the light travels a much longer effective path length through the gas, simultaneously achieving fast response time and high sensitivity
Solution Approach 2:
The curved reflective surfaces guide the optical beam through an extended path that maximizes the interaction length with the gas sample. The curved geometry allows the optical path to follow a longer trajectory through the gas diffusion chamber, increasing sensitivity without requiring a larger chamber volume that would increase gas diffusion time
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
The detector achieves high accuracy and precision in gas detection with customizable optical paths, ensuring adaptability to various gases, compact dimensions, and increased reliability, while maintaining ease of production and cost-effectiveness.
Implementation Method 1
The NDIR sensors detect the attenuation of the infrared ((IR) luminous radiation caused by a target gas present in a gas sample. The degree of attenuation is a function of the absorption wavelength of the IR radiation, of the length of the optical path covered by the same, of the nature and concentration of the target gas present along said optical path
Implementation Method 2
variable geometry optical gas detector with a cup-shaped body and disc-shaped lid, featuring interchangeable reflector elements that allow the optical path to be configured based on the gas type, enabling adjustable length and orientation of the electromagnetic radiation path
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
An optical gas detector (20) in metal or other suitable material, comprising a cup-shaped body (1), with upper mouth (9) closed by a lid (2) the bottom of which (8) is flat and provided with a plurality of through holes (15) variously arranged, which place said detector (20) in communication with the outside environment, and inside which an IR source (10) and an IR analyser (11) are placed, borne by an overlying circuit board (12). The inner lateral surface of the body (1) forming a first reflector wall (6) having a regular or irregular annular extension and defining, in conjunction with a second convex or concave reflector wall (7, 7') of a shaped appendage (5) and with one or more reflectors (3, 3', 21, 22, 23,24,25) pre-inserted and positioned in the body (1), a multiplicity of geometrically alternative optical paths (4, 4', 4", 4"') of the electromagnetic radiation emitted by the IR source (10) and detected by the IR analyser (11).