Turbidimeter Annular Mirror Optical System for Measurement Accuracy

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Solution Overview

Problem

Conventional turbidimeters are sensitive to geometrical inaccuracies and local inhomogeneities in the optical arrangement and turbidity of liquid samples, leading to reduced accuracy in measuring turbidity.

Innovation Solution

A turbidimeter design featuring an annular 45° collecting mirror and concentration mirror, along with a scattering body, which directs and diffuses scattered light to improve signal detection and reduce the impact of geometrical inaccuracies and inhomogeneities, using a parallel light beam and a scattering body with micro-particles to enhance light scattering and detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional light detection in a single sector is used, then the device complexity is low, but the measurement precision is reduced due to low signal intensity

Engineering Contradiction:
Improveturbidity measurement accuracyVSAvoidoptical arrangement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The optical system is segmented into multiple functional components: a light source generating parallel beams, a scattering body with micro-particles for light diffusion, annular collecting mirrors at 45° angles, and a scattering light detector. This segmentation allows each component to perform its specific function optimally, improving overall measurement precision while maintaining manageable device complexity through modular design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A scattering body containing micro-particles is introduced as an intermediary between the light source and the detector. This scattering body diffuses the light beam to create scattered light that can be collected by the annular mirrors and directed to the detector, enabling accurate turbidity measurements without requiring direct detection of weak scattered light from the sample alone.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If circular mirror arrangements are used to increase signal detection, then the signal-to-noise ratio improves, but the device becomes highly sensitive to geometrical inaccuracies

Engineering Contradiction:
Improvesignal-to-noise ratioVSAvoidsensitivity to geometrical inaccuracies
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The annular collecting mirrors are positioned at specific 45° angles relative to the light beam axis, creating localized optimal detection zones. This local quality approach ensures that scattered light from specific regions of the sample is efficiently collected and directed to the detector, improving signal-to-noise ratio while reducing sensitivity to overall geometrical variations through localized optimization.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The optical system parameters are optimized with annular mirrors positioned at 45° angles and a specific arrangement relative to the light beam and scattering body. This parameter optimization ensures that the system maintains high signal-to-noise ratio while being tolerant to geometrical inaccuracies, as the 45° angle configuration provides a robust optical path that compensates for minor alignment variations.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If conventional single-point light detection is used, then the device complexity is low, but the detection of scattered light from the complete circumference is insufficient

Engineering Contradiction:
Improvelight scattering detection completenessVSAvoidmirror and optical arrangement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The detection system transitions from single-point detection to annular/circumferential detection by positioning the light detector to receive scattered light over the complete circumference of the light beam. The annular 45° collecting mirrors extend the detection capability from a single point to a three-dimensional annular region, ensuring complete capture of scattered light from all azimuthal angles around the beam axis.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The annular collecting mirrors serve multiple functions: they collect scattered light from the entire circumference, redirect it at 45° angles, and direct it to the scattering light detector. This multi-functionality allows a single optical arrangement to achieve complete circumferential light detection without requiring multiple separate detection systems, balancing measurement completeness with device simplicity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 design increases the accuracy and tolerance of turbidity measurements by ensuring that all scattered light is detected, regardless of cuvette positioning or optical arrangement inaccuracies, thereby improving the signal-to-noise ratio and reducing the effect of local turbidity inhomogeneities.

Implementation Method 1

A light source generates a parallel light beam in the sample cuvette

Methodology Applied
Scientific EffectLight: Light

Implementation Method 2

A scattering body is arranged concentric to the annular 45° collecting mirror. A scattering light detector is arranged to receive light scattered by a scattering body

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 3

An annular 45° collecting mirror surrounds the sample cuvette. The annular 45° collecting mirror is arranged concentric to a light beam

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 4

An annular 45° concentration mirror is arranged coaxially to the annular 45° collecting mirror. The annular 45° concentration mirror surrounds the scattering body and is arranged optically opposite to the annular 45° collecting mirror

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP2997350B1turbidimeter
Publication Date: 2018.09.19 HACH LANGE HACH LANGE
  • EP2997350B1 patent drawingFigure 1
  • EP2997350B1 patent drawingFigure 2

AI summary

A turbidimeter (10) for measuring a turbidity of a liquid sample (34) in a sample cuvette (30) includes a cuvette receiving means (33) for positioning the sample cuvette (30) in a defined cuvette position (36). A light source (20) generates a parallel light beam (24) in the sample cuvette (30). An annular 45° collecting mirror (12) surrounds the sample cuvette (30). The annular 45° Collecting mirror (12) is arranged concentric to a light beam (24). A cylindrical scattering body (44) is arranged concentric to the annular 45° collecting mirror (12). A scattering light detector (50) is arranged to receive light scattered by a scattering body (44). An annular 45° concentration mirror (40) is arranged coaxially to the annular 45 collecting mirror (12). The annular 45° concentration mirror (40) surrounds the scattering body (44) and is arranged optically opposite to the annular 45° collecting mirror (12).