Optical Cavity with Parabolic and Hyperbolic Mirrors for Multi-Gas Sensing
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Solution Overview
Problem
Existing gas sensors face challenges in using a single laser beam as a light source for measuring various gases, as each gas requires a specific wavelength band, and they struggle to maintain excellent converging and straightness properties of light, limiting their ability to accurately measure gas concentrations across multiple types of gases.
Innovation Solution
An optical cavity design incorporating a first parabolic reflective surface, a second parabolic reflective surface, and a hyperbolic reflective surface, where the hyperbolic surface's vertex values are optimized to adjust the optical path length and improve light converging properties, allowing for the use of a multi-wavelength light source and suitable for measuring different gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single laser beam is used as a light source for measuring various gases, then the device complexity is reduced, but the measurement precision deteriorates because each gas requires a specific wavelength band
Solution Approach 1:
The patent employs a broadband light source that can measure multiple types of gases (CO, CO2, CH4, N2O, HFCs, PFCs, SF6) with different wavelength absorption bands using a single optical cavity system. The optical cavity is designed with reflective surfaces that work across multiple wavelength ranges, eliminating the need for separate laser beams for each gas type while maintaining measurement precision through wavelength-selective detection.
2Measurement precision
If the optical path length is increased to increase light absorption amount, then the measurement precision improves, but the device complexity increases due to difficulty in focusing light on photodetector
Solution Approach 1:
The patent utilizes curved reflective surfaces (parabolic and hyperbolic mirrors) arranged in specific geometric configurations to guide and focus light over extended optical paths. The parabolic mirror reflects light from its focus to parallel rays, while the hyperbolic mirror focuses parallel rays to its other focus, enabling long optical paths with precise light convergence on the photodetector without complex focusing mechanisms.
3Manufacturing precision
If only parabolic reflective surfaces are used in the optical cavity, then the manufacturing precision is improved due to simplicity, but the light converging properties deteriorate
Solution Approach 1:
The patent combines parabolic and hyperbolic reflective surfaces in a composite optical cavity system. The parabolic mirror provides simple manufacturing with good reflectivity, while the hyperbolic mirror enhances light convergence by focusing parallel rays to its other focus. This composite configuration achieves both ease of manufacture and superior light converging properties that neither surface could achieve alone.
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 design enables the use of a multi-wavelength light source with excellent converging and straightness properties, allowing for accurate measurement of gas concentrations across various gases, and allows for adjustable optical path lengths to suit different gases, enhancing the measurement accuracy and versatility of gas sensors.
Implementation Method 1
a first parabolic reflective surface formed on one wall surface in the space; a second parabolic reflective surface which is formed at a position facing the one wall surface, and is configured to reflect again a light emitted from a light source disposed at a focus of the first parabolic reflective surface and reflected by the first parabolic reflective surface so as to change a traveling path of the light
Implementation Method 2
a hyperbolic reflective surface formed so that any one focus of two foci coincides with a focus of the second parabolic reflective surface, and is configured to reflect the light made incident from the second parabolic reflective surface to change the traveling path of the light
Implementation Method 3
in order for the non-dispersion type gas sensor to exhibit excellent sensing characteristics, an amount of absorption of light in an optical cavity of the gas sensor should be increased
Data Source
AI summary
The present invention provides an optical cavity for a gas sensor having a space defined therein, including: a first parabolic reflective surface formed on one wall surface in the space; a second parabolic reflective surface which is formed at a position facing the one wall surface, and is configured to reflect again a light emitted from a light source disposed at a focus of the first parabolic reflective surface and reflected by the first parabolic reflective surface so as to change a traveling path of the light; and a hyperbolic reflective surface formed so that any one focus of two foci coincides with a focus of the second parabolic reflective surface, and is configured to reflect the light made incident from the second parabolic reflective surface to change the traveling path of the light, and a value of c2−b2 of a hyperbola equation of hyperbola forming the hyperbolic reflective surface is in a range of 0<c2−b2≤4 mm.