Variable-Path Immersion Probe With V-Shaped Optical Windows

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Solution Overview

Problem

Conventional immersion probes with fixed path lengths for fluid analysis suffer from limited dynamic measurement range, nonlinearities near saturation limits, and inaccuracies due to deviations in path length, especially at high component concentrations, leading to compromised measurement accuracy.

Innovation Solution

A submersible probe design with wedge-shaped optical windows and movable light deflection devices allows for variable path lengths by relative movement, enabling continuous recording of spectra at multiple path lengths and preventing unwanted reflections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed path length is used in conventional immersion probes, then the device structure is simple, but the dynamic measurement range is limited and nonlinearities occur near saturation limits

Engineering Contradiction:
Improvedynamic measurement rangeVSAvoiddevice structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a variable path length measurement cell where the optical path length can be dynamically adjusted during measurements. This is achieved through a movable component that changes the distance between optical surfaces, allowing the system to adapt to different concentration ranges and extend the dynamic measurement range while avoiding saturation nonlinearities.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the optical path length parameter to extend the dynamic measurement range. By varying this critical parameter, the system can accurately measure both low and high concentrations of analytes, preventing the nonlinearities that occur at saturation limits with fixed path length systems.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If a fixed path length is used, then the device structure is simple, but measurement accuracy is compromised at high component concentrations

Engineering Contradiction:
Improvemeasurement accuracyVSAvoiddevice structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The variable path length measurement cell allows the system to dynamically adjust the optical path length based on the concentration of the analyte. At high concentrations, a shorter path length prevents saturation and maintains measurement accuracy, while at low concentrations, a longer path length provides sufficient signal.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

By changing the optical path length parameter, the system optimizes measurement accuracy across different concentration ranges. This parameter adjustment prevents the nonlinearities and inaccuracies that occur at saturation limits with fixed path length systems.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If path length deviations occur, then the device operation is simple, but quantitative analysis accuracy is compromised

Engineering Contradiction:
Improvequantitative analysis accuracyVSAvoidpath length control
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent incorporates feedback mechanisms to maintain precise path length control. Sensors detect the actual optical path length and provide feedback to control systems that adjust the movable components to compensate for deviations, ensuring accurate quantitative analysis.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces purely mechanical path length setting with a combination of mechanical positioning and optical/electronic feedback control. This substitution allows for more precise and stable path length maintenance, reducing deviations that would compromise quantitative analysis accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 achieves significantly higher measurement accuracy and extended dynamic range by determining absorbance as a function of path length, allowing precise concentration determinations of fluid components with reduced nonlinearities and reflections.

Implementation Method 1

light from a light source is introduced into the probe via optical fibers

Methodology Applied
Scientific EffectOptical fiber transmission: Optical Fibre

Implementation Method 2

analyzing the light passing through the fluid by absorption spectroscopy

Methodology Applied
Scientific EffectAbsorption spectroscopy: Absorption Spectroscopy

Implementation Method 3

at least one light deflection device which is arranged in the light path of the light exiting the input light guide or entering the output light guide and which directs the light coming from the input light guide through the first optical window into the fluid or into the output light guide

Methodology Applied
Scientific EffectLight refraction and deflection: Refraction

Data Source

PatentEP4405667B1Immersion probe having variable path length
Publication Date: 2025.12.03 IMPLEN
  • EP4405667B1 patent drawingFigure 1~2
  • EP4405667B1 patent drawingFigure 3a~4b
  • EP4405667B1 patent drawingFigure 5a~6c

AI summary

The invention relates to an immersion probe (1) for the quantitative and/or qualitative analysis of a fluid (F), e.g. a liquid or a gas, using light which is guided through the fluid (F) along a light path (L), comprising a measuring head (10) suitable for immersion in the fluid, having: an input light guide (14) for the light guided to the fluid (F), which input light guide can be connected to a light source; an output light guide (15) for the light guided out of the fluid (F), which output light guide can be connected to a detector; a first and a second optical window, the faces of which facing each other are in contact with the fluid; and at least one light deflection device (17, 18), which is arranged in the light path of the light exiting the input light guide (14) and entering the output light guide (15) and deflects the light coming from the input light guide (14) through the first optical window into the fluid and the light coming from the fluid to the output light guide (15). The immersion probe is characterised in that the first and the second optical window (20, 21) are arranged with respect to each other in a V shape and their surfaces (20a, 21a) pointing toward the interior of the V face the fluid (F) being analysed, wherein the at least one light deflection device (17, 18) and the optical windows (20, 21) can move back and forth relative to each other substantially in the direction of the opening of the V.