Optical Sensor Device for Liquid Fill Level and Refractive Index
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Solution Overview
Problem
Current technologies for measuring the fill level and refractive index of liquids in containers are either invasive, require significant installation space, or lack precision, particularly in determining the correct composition of liquids to prevent incorrect refueling.
Innovation Solution
An optical sensor device that uses a laser light source, deflection device, and photo element to measure the fill level and refractive index separately via optical path lengths, employing self-mixing interferometry to determine variations in light intensity and path lengths, allowing for accurate detection of liquid composition without extensive assembly or space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensor concepts (ultrasonic, thermal conductivity, viscosity, density, electrical permeability) are used to determine liquid composition, then the measurement can be performed, but the sensors are either invasive, require significant installation space, or lack precision
Solution Approach 1:
The patent replaces mechanical/invasive sensor concepts (ultrasonic, thermal conductivity, viscosity, density, electrical permeability) with optical measurement methods. Specifically, it uses refractometric measurement of light refraction at the liquid interface and wavelength-dependent light absorption to determine liquid composition and fill level non-invasively, eliminating the need for invasive sensors and reducing installation space requirements.
Solution Approach 2:
The optical sensor device performs multiple functions: it measures both fill level and refractive index (liquid composition) using a single integrated optical sensor unit. The device uses a light source and detector arrangement that can measure both the refraction of light at the liquid interface and the absorption characteristics of the liquid, providing multi-parameter measurement without requiring separate sensors for each function.
2Measurement precision
If refractometric sensors are used to determine liquid composition, then precision can be improved, but the device requires significant installation space
Solution Approach 1:
The patent merges the fill level measurement function and refractive index measurement function into a single integrated optical sensor device. The device uses a single light source and detector arrangement that can perform both measurements by utilizing different optical paths and measurement principles within the same housing, thereby reducing the overall installation space requirement while maintaining high precision for both functions.
3Ease of operation
If optical measurement methods are used for fill level and refractive index measurement, then non-invasive measurement is achieved, but the device complexity increases
Solution Approach 1:
The patent segments the optical measurement system into distinct functional components: a light source unit, a detector arrangement, and an evaluation device. The light source generates light beams that travel through the liquid, the detector measures the refracted and absorbed light, and the evaluation device processes the signals to determine fill level and refractive index. This segmentation allows for modular design and simplified installation while maintaining non-invasive measurement capability.
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 precise and non-invasive measurement of fill level and refractive index, preventing incorrect refueling by accurately determining liquid composition with minimal installation space, using a compact design that enhances measurement accuracy and sensitivity.
Implementation Method 1
a refractometric sensor is known that determines the refraction of light at the interface with the liquid to infer the concentration of urea-water solutions
Implementation Method 2
the laser beam can be reflected back from the scattering element and from a container roof at least partially into the laser light source and coupled into it
Implementation Method 3
a photoelectric element, which is arranged on or in the laser light source and through which an intensity of the laser beam emitted by the laser light source can be detected
Data Source
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AI summary
The invention relates to an optical sensor device (10) for measuring a fill level (h) and/or the refractive index (n) of a liquid (F) in a container (1), comprising: a housing (G) which can be installed on a base or a lateral wall of the container (1); a laser light source (2) which is arranged in the housing (G) and by means of which a laser beam (L) can be generated and emitted into the liquid (F); a deflecting device (3) for the laser beam (L) which is arranged in or on the housing (G) and by means of which the laser beam (L) can be emitted in the direction of a liquid surface (FS) and into the liquid (F) and/or substantially parallel to the liquid surface (FS) and can be oriented towards a scattering element (StE) within the liquid (F), wherein the laser beam (L) can be at least partly reflected back into the laser light source (2) by the scattering element (StE) and/or by a container lid (1a) and can be coupled into the laser light source, the scattering element (StE) is arranged in or on the housing (G), and the liquid (F) can pass at least partly through the housing (G) or can surround same; a photo element (FE) which is arranged on or in the laser light source (2) and by means of which the intensity of the laser beam (L) emitted by the laser light source (2) can be detected; and an analysis device (AE) for ascertaining the fill level (h) and/or the refractive index (n). The fill level (h) can be ascertained from the optical path length of the laser beam (L) between the laser light source (2) and the container lid (1a), said container lid (1a) being arranged above the liquid surface (FS), and/or the refractive index (n) can be ascertained from the optical path length between the laser light source (2) and the scattering element (StE). In each case, the optical path length can be ascertained from a variation in the intensity of the laser beam (L) emitted by the laser light source (2). The optical sensor device also comprises a controller (SE), by means of which the laser light source (2) can be operated with a modulation signal.