Multi-wavelength Water Sensor UV Resolution and Turbidity Compensation
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Solution Overview
Problem
Existing instruments for measuring organic and nitrogen compounds in water struggle to achieve less than one nm wavelength resolution in the UV light region while also compensating for interference from particulate, colloids, and other turbidity causing compounds, leading to poor measurement performance in challenging applications.
Innovation Solution
A submersible apparatus with a broadband light source, optical slit, diffraction grating, and line sensor array is used to measure light absorption in the UV, visible, and near infrared spectra, achieving less than one nm wavelength resolution and compensating for interference by alternating reference and measurement light beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a diffraction grating with high wavelength resolution (less than one nm) is used in the UV light region, then the capability to distinguish between compounds with similar absorption spectrums (such as nitrate and nitrite) is improved, but the ability to measure visible and near infrared wavelengths for compensating turbidity interference is lost
Solution Approach 1:
The patent divides the measurement function into two independent segments: a high-resolution UV measurement path using a first diffraction grating for distinguishing nitrate and nitrite, and a separate visible/NIR measurement path using a second diffraction grating for turbidity compensation. This segmentation allows each segment to be optimized for its specific function without compromise.
Solution Approach 2:
The patent creates a multi-functional instrument that can simultaneously perform high-resolution UV spectroscopy for compound identification and visible/NIR spectroscopy for turbidity measurement. The dual-grating system enables the single instrument to fulfill multiple measurement objectives that previously required separate instruments.
2Adaptability or versatility
If a diffraction grating design is optimized for full UV/VIS wavelength range with five nm resolution, then the wavelength range coverage is improved, but the capability to distinguish compounds with similar absorption spectrums requiring less than one nm resolution is insufficient
Solution Approach 1:
The patent applies local quality by assigning different resolution characteristics to different wavelength regions: the first diffraction grating provides high resolution (less than one nm) specifically in the UV region where compound discrimination is critical, while the second diffraction grating provides adequate resolution across the broader visible and near infrared range for turbidity measurement.
3Measurement precision
If reagent-based measurement methods are used in lab instruments, then the measurement accuracy for organic and nitrogen compounds is improved, but the measurement time increases with several hours of reaction time required
Solution Approach 1:
The patent replaces the chemical reaction-based measurement system with an optical measurement system using spectroscopy. Instead of adding reagents that require hours to react, the instrument uses light absorption measurements in the UV, visible, and near infrared regions to directly detect and quantify organic and nitrogen compounds, achieving both accuracy and speed.
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 apparatus provides accurate, real-time measurement of organic and nitrogen compounds in water by resolving narrow ultraviolet bandwidths and compensating for interference, enhancing measurement precision and reliability.
Implementation Method 1
The broadband light source configured to output broadband light in an ultraviolet light spectrum and light in one or more of a visible light spectrum and a near infrared light spectrum. The measurement region includes the liquid sample, which propagates the broadband light emitted from the broadband light source.
Implementation Method 2
The diffraction grating configured to resolve the broadband light propagating from the optical slit into a plurality of resolved and substantially adjacent narrow ultraviolet bandwidth regions
Implementation Method 3
the line sensor array configured to detect a plurality of individual light intensities corresponding to the ultraviolet bandwidth regions produced by the diffraction grating
Implementation Method 4
A submersible apparatus with a broadband light source, optical slit, diffraction grating, and line sensor array is used to measure light absorption in the UV, visible, and near infrared spectra
Data Source
AI summary
An apparatus and method for measuring absorption of a liquid at several highly resolved wavelengths in the ultraviolet light spectrum with additional wavelengths or wavelength groups in the visible and/or near infrared light spectrum is provided. The apparatus includes a submersible housing that incorporates a broad band light source that emits ultraviolet, visible, and near infrared light, optical windows defining a measurement region of the liquid, an optical chopper unit to alternate between reference and measured light beams, an optical sensor to detect a specific wavelength or group of wavelengths in the visible or near infrared light spectrum from the broadband light source, a slit to define the broadband light geometry onto a diffraction grating, the diffraction grating to modify the broad band light beam into highly wavelength resolved ultraviolet wavelengths, and a line sensor to detect the highly wavelength resolved ultraviolet light.