Polarized Millimeter-Wave Strain Measurement for Thick Materials

Solution Overview

Problem

Existing methods for determining stress in materials are limited to optically transparent materials and thin objects, require complex optical setups, and cannot measure large stress differences in thicker materials.

Innovation Solution

Use electromagnetic radiation with frequencies between 1 GHz and 10 THz to determine refractive indices for different polarization directions, allowing for stress measurement in thicker materials by comparing refractive indices and birefringence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optical measurement methods are used to determine strain, then measurement can be performed on optically transparent materials, but the method is limited to thin materials and cannot measure larger tension differences

Engineering Contradiction:

Improvestrain measurement capabilityVSAvoidapplicability to thick and opaque materials

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent changes the wavelength parameter of the electromagnetic radiation from optical range to millimeter or sub-millimeter range. This parameter change enables the radiation to penetrate thicker and opaque materials while still allowing strain measurement through refractive index comparison for differently polarized radiation components

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the complex optical measurement system with a simplified electromagnetic radiation-based system. Instead of using numerous optical components to evaluate small path length differences, the invention uses millimeter or sub-millimeter radiation to directly measure refractive index differences caused by strain, eliminating the need for complex optical setups

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If optical measurement methods with numerous optical components are used, then strain can be determined in transparent materials, but the measurement setup becomes complex

Engineering Contradiction:

Improvestrain determination accuracyVSAvoidnumber of optical components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex optical measurement system with a simplified electromagnetic radiation-based system. Instead of using numerous optical components to evaluate small path length differences, the invention uses millimeter or sub-millimeter radiation to directly measure refractive index differences caused by strain, eliminating the need for complex optical setups

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the wavelength parameter of the electromagnetic radiation from optical range to millimeter or sub-millimeter range. This parameter change enables the radiation to penetrate thicker and opaque materials while still allowing strain measurement through refractive index comparison for differently polarized radiation components

Inventive Principle:

Principle #35Parameter changes

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 accurate stress measurement in thicker, opaque materials by using longer wavelengths, simplifying the setup and allowing for non-contact measurements in production lines, with the potential to measure larger path length differences and reduce unnecessary heating.

Implementation Method 1

the object is irradiated with electromagnetic radiation having a wavelength in the millimetre or sub-millimeter range and different polarisation directions

Methodology Applied

Scientific EffectPolarization: Polarisation

Implementation Method 2

the radiation at least partially penetrating the object and being reflected at boundary surfaces of the object

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

the refractive index of the material of the object is determined from the received radiation for the differently polarized radiation components

Methodology Applied

Scientific EffectBirefringence: Birefringence

Data Source

PatentEP4556196B1Method and device for determining a strain on an object

Publication Date: 2026.05.06 SIKORA AG

Figure 1~2

AI summary

The invention relates to a method for determining the strain of an object, in particular a strand-shaped object, wherein the object is irradiated with electromagnetic radiation having a wavelength in the millimeter or submillimeter range and different polarization directions, wherein the radiation at least partially penetrates the object and is reflected at interfaces of the object, the radiation is received after the at least partial penetration and reflection at interfaces of the object, the refractive index of the material of the object is determined from the received radiation for the differently polarized radiation components, and the strain of the object is determined from a comparison of the determined refractive indices. The invention also relates to a corresponding device.