Fluorescent Infrared Sensor for CO2 Detection
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Solution Overview
Problem
Existing optical sensors for detecting gaseous species like CO2 in the mid-infrared range face challenges with low brightness thermal sources, high attenuation in chalcogenide glass fibers, temperature-sensitive LEDs, and complex and expensive laser systems, limiting remote operation and sensitivity.
Innovation Solution
An optical sensor using a fluorescent source with a chalcogenide glass matrix doped by rare earth ions, excited by a remote semiconductor laser, which generates incoherent infrared radiation with improved brightness and stability, allowing for differential detection and long-distance operation via conventional optical fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thermal source of the black body type is used for infrared radiation generation, then the source can be implemented simply, but the brightness is low and the emission spectrum is excessively wide
Solution Approach 1:
The patent changes the fundamental operating parameter of the radiation source from thermal emission (black body type) to fluorescent emission. By using a fluorescent source with specific wavelength emission characteristics, the system achieves higher brightness and narrower spectral width while maintaining relative simplicity in implementation.
2Length of stationary object
If chalcogenide glass optical fibers are used to transport infrared radiation remotely, then remote detection is enabled, but the attenuation level is high (0.1 to 1 dB/m)
Solution Approach 1:
The patent introduces an intermediary conversion system where the fluorescent source converts infrared radiation to visible light, which is then transported through standard optical fibers. This intermediary conversion allows remote detection while using conventional, lower-attenuation optical fibers instead of chalcogenide glass fibers.
3Ease of manufacture
If LEDs are used as infrared radiation sources, then the source is simple and inexpensive, but the spectrum varies greatly with temperature making differential detection difficult
Solution Approach 1:
The patent changes the radiation source from LED to fluorescent source with specific wavelength emission characteristics. This parameter change results in a stable spectrum that is insensitive to ambient temperature variations, thereby enabling reliable differential detection while maintaining source simplicity.
4Illumination intensity
If lasers with rare earth ions in chalcogenide glass matrix are used, then high brightness and narrow spectrum are achieved, but the system becomes complex and expensive
Solution Approach 1:
The patent extracts the complex laser system and replaces it with a simpler fluorescent source. By removing the need for complex laser mechanisms while maintaining the beneficial fluorescent emission characteristics, the system achieves high brightness and narrow spectral width with significantly reduced complexity and cost.
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 solution provides a highly sensitive and stable optical sensor capable of detecting gaseous CO2 over long distances with reduced electromagnetic interference and high temperature tolerance, offering improved brightness and ease of implementation compared to prior technologies.
Implementation Method 1
a fluorescent source of incoherent infrared radiation comprising a chalcogenide glass matrix doped by rare earth ions
Implementation Method 2
a pumping source emitting visible or infrared radiation adapted to excite the fluorescence of said rare earth ions. Typically, the pumping source may be a semiconductor laser emitting in the visible or in the near infrared
Implementation Method 3
at least one infrared radiation detector provided with a spectrum selector device and arranged to detect the radiation emitted by said fluorescent source, a chemical species detection zone being provided between said source and said detector
Data Source
AI summary
The invention relates to a chemical species optical sensor comprising: a fluorescent source (3) of incoherent infrared rays, including a chalcogenide glass matrix, doped with rare earth ions and combined with a pump source by means of a first optical fiber (2); and at least one infrared ray detector (5), provided with a spectral selection device (50) and set up to detect the rays that are emitted by said fluorescent source and have passed through a detection area (6), said detector including a fluorescent element (510) formed by a chalcogenide glass matrix that is doped with rare earth ions and combined with a second pump source (530) by means of a second optical fiber (520). Such a sensor can be used for differentially detecting a chemical species, and in particular CO2.