Liquid presence/turbidity sensor using single optical channel
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Solution Overview
Problem
Current turbidity sensors with a single optical channel cannot reliably distinguish between air and turbid water due to similar light attenuation levels, leading to inaccurate measurements.
Innovation Solution
A multisensor system using a single optical channel with refractive elements that focus light in an air environment, where the introduction of water causes defocusing, allowing for distinct light intensity changes to differentiate between air and water, including varying turbidities, using circular, cylindrical, or sphero-cylindrical lenses to enhance light transmission and accommodate optical misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single optical channel is used to maximize light transmission in liquid, then light transmission is improved, but the ability to distinguish between air and turbid water deteriorates
Solution Approach 1:
The patent changes the optical parameters by introducing refractive elements (lenses) that focus light differently depending on the medium. The lenses are designed to focus light when in contact with air (higher index of refraction difference) and defocus when in contact with water (lower index of refraction difference), creating distinct light intensity patterns at the detector that enable both high transmission and accurate distinction between air and turbid water.
2Illumination intensity
If refractive elements are designed to focus light in air environment, then light transmission is improved, but the system becomes sensitive to water introduction causing defocusing
Solution Approach 1:
The patent exploits the parameter change in refractive index when water replaces air. The refractive elements are specifically designed with optical parameters (focal length, curvature) that create a strong focusing effect in air but cause defocusing when water is introduced. This deliberate parameter sensitivity to medium change is the core mechanism for detecting liquid presence while maintaining high light transmission in air.
3Measurement precision
If two optical channels are used to distinguish between air and liquid, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of two separate optical channels into a single channel by using refractive elements that provide both focusing (for high transmission) and medium-detection (for fluid differentiation) capabilities. Instead of using two independent light paths with separate transmitters and detectors, the invention combines these functions into one optical path with strategically placed lenses that respond differently to air and water presence, thereby reducing component count while maintaining measurement accuracy.
Solution Approach 2:
The refractive elements serve multiple functions simultaneously: they focus light to maximize transmission through the sampling volume, and they also act as the sensing mechanism for detecting liquid presence by defocusing when water is introduced. This multi-functionality eliminates the need for separate detection mechanisms, reducing overall system complexity while achieving both high transmission and accurate fluid differentiation.
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
Enables unambiguous distinction between air and water of different turbidities, reducing parts count and improving measurement accuracy by detecting multiple light transmission levels, allowing for effective turbidity sensing and fluid differentiation.
Implementation Method 1
optical elements in contact with liquid in the channel that change their index of refraction
Implementation Method 2
focusing the light between the light transmitter and the light detector using refractive elements
Implementation Method 3
The turbidity of a liquid in a sampling volume may be measured by assessing how much light passes between a light transmitter and light detector
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A multisensor employs an optical system that is modified by the index of refraction of fluid passing between a light emitter and light detector to successfully distinguish between air and water (of any turbidity) and between water of different turbidity values. The optical system may employ lenses contacting the fluid to change their focal length and thus to focus and defocus light on the light detector depending on an index of refraction of the fluid.