Fluid Analyzer Self-Check Assembly for Trace Liquid Detection
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Solution Overview
Problem
Existing Fourier transform infrared (FTIR) spectroscopy systems face challenges in accurately analyzing trace components in liquids due to low optical power, small probe path lengths, and angle-dependent signal distortion in attenuated total reflectance (ATR) interfaces, leading to poor repeatability and sensitivity for liquid characterization.
Innovation Solution
A fluid analyzer with a self-check assembly that includes a check frame and a tunable laser system, allowing for adjustable gain settings and leak detection, coupled with a signal detector assembly to evaluate sample performance and adjust gain settings based on absorbance, enhancing sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If FTIR spectrometers use broadband globar incandescent source, then the system can perform infrared spectroscopy of liquids, but the optical power per wavelength is low resulting in small probe path lengths and poor sensitivity for trace detection
Solution Approach 1:
The patent replaces the broadband globar incandescent source with a quantum cascade laser (QCL) source, which provides high optical power at specific infrared wavelengths. This substitution of the light source mechanism enables long probe path lengths (up to 10 meters) through free-space or waveguide transmission, achieving trace detection sensitivity while maintaining liquid spectroscopy capability
Solution Approach 2:
The patent changes the spectral parameters by using a tunable QCL source that can be tuned across mid-infrared wavelengths (3-12 micrometers). This parameter change allows optimization of optical power at specific absorption wavelengths of target analytes, enabling both high sensitivity trace detection and adaptation to different liquid components
2Length of stationary object
If ATR interfaces are used to increase path length, then liquid analysis is enabled, but the spectral signatures are distorted due to combined absorption and refractive index effects
Solution Approach 1:
The patent extracts the liquid sample from the ATR interface configuration and places it in free-space transmission cells or waveguide cells. This removes the distorting ATR mechanism (evanescent wave coupling with varying refractive index) while maintaining long probe path lengths through direct transmission geometry, preserving accurate spectral signatures
Solution Approach 2:
The patent introduces infrared-transparent windows (such as zinc selenide or diamond windows) as intermediaries to contain the liquid sample in free-space transmission cells. These windows enable long path length measurement without direct contact between the sample and optical components, avoiding spectral distortion while maintaining measurement accuracy
3Length of stationary object
If ATR technique is used for liquid spectroscopy, then path length is increased, but measurement repeatability becomes poor due to sensitivity to angle of incidence
Solution Approach 1:
The patent replaces the ATR optical geometry (which requires precise control of angle of incidence) with free-space transmission or waveguide transmission geometry. This substitution eliminates the angle-of-incidence sensitivity issue entirely, as the light simply passes through the sample in a fixed, well-defined path, greatly improving measurement repeatability
4Measurement precision
If long probe path lengths are used for trace detection, then sensitivity improves, but the system becomes more complex and harder to align
Solution Approach 1:
The patent employs infrared waveguide cells that can function both as transmission media for long path length measurement and as self-aligning optical components. The waveguide structure inherently guides the infrared beam over long distances without requiring precise external alignment, reducing system complexity while maintaining trace detection sensitivity
Solution Approach 2:
The patent introduces infrared-transparent windows and waveguide structures as intermediary components that simplify alignment. These intermediaries provide mechanical support and optical guidance, allowing long path length measurement without requiring complex alignment procedures for free-space optics
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 system improves the ability to accurately analyze trace components in liquids by optimizing gain settings and detecting leaks, thereby increasing sensitivity and repeatability in liquid spectroscopy.
Implementation Method 1
Infrared spectroscopy of liquids is useful for characterizing liquid components. Different liquid or dissolved chemicals have strong identifying absorption features in the infrared wavelengths.
Implementation Method 2
the path lengths through liquids that can be probed are quite small before the probe light is attenuated to unacceptably low values
Data Source
AI summary
A fluid analyzer (214) that analyzes a sample (12) includes an analyzer frame (236); a test cell assembly (242) that receives the sample (12); a laser assembly (238) that generates a laser beam (239A); a signal detector assembly (232); and a self-check assembly (230). The self-check assembly (230) includes (i) a check frame (230A); (ii) a check substance (230E) with known spectral characteristics; and (iii) a check frame mover (230B) that selectively moves the check frame (230A) between a self-check position (231B) and a test position (231A) relative to the analyzer frame (236). In the self-check position (231B), the laser beam (239A) is directed through the check substance (230E) to evaluate the performance of the fluid analyzer (214). In the test position (231A), the laser beam (239A) is directed through the sample (12) in the test cell assembly (242) to evaluate the sample (12).