Polarisation Selective Imaging Retro-Reflector Contrast

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Solution Overview

Problem

Traditional measuring machines face challenges in achieving high-precision imaging and accurate measurements due to limitations in illumination techniques, particularly with backlight illumination, which results in weakened contrast and reduced scalability for larger machines.

Innovation Solution

The proposed solution involves using a retro-reflecting element behind the object to convert top light into bottom light, combined with polarized light and additional polarizing elements to select between reflected light from the object and the retro-reflected light, thereby enhancing image contrast and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If backlight illumination is used to illuminate the object from below, then the illumination can reach the object surface, but the image contrast is weakened and the system becomes less scalable

Engineering Contradiction:
Improveillumination reachVSAvoidimage contrast
Core Design Contradiction:
Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent inverts the traditional backlight illumination approach by using a retro-reflector to redirect light from the imaging side back through the object. Instead of placing the light source below the object, the light source remains on the imaging side and the retro-reflector redirects the light back through the object, achieving backlight illumination效果 without the associated contrast problems

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The retro-reflector acts as an intermediary element that mediates between the light source and the object. It receives light from the light source, redirects it through the object, and returns it to the imaging system, enabling the light to effectively illuminate the object from below without requiring a physical light source positioned below the object

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If separate light sources are used for top light and bottom light illumination, then both illumination methods can be provided, but the device complexity increases

Engineering Contradiction:
Improveillumination methodsVSAvoidlight source configuration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The single light source is designed to serve multiple functions by illuminating the object through different paths. The same light source provides both direct top-light illumination and, through the retro-reflector, indirect bottom-light illumination, eliminating the need for separate light sources while maintaining versatility

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

Solution Approach 2:

The patent merges the functions of multiple light sources into a single light source system. By combining the direct illumination path and the retro-reflected illumination path, the system achieves both top-light and bottom-light illumination capabilities with a single light source, reducing device complexity

Inventive Principle:
Principle #5Merging (Combining)

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

This approach allows for high-contrast, high-accuracy imaging and measurement by effectively utilizing top and bottom light illumination methods with a single light source, improving measurement precision and scalability of measuring machines.

Implementation Method 1

utilizing a retro-refacting element behind an object to be imaged or to be measured, thereby converting top light into bottom light

Methodology Applied
Scientific EffectRetro-reflection: Retroreflector

Implementation Method 2

By providing polarised light and additional polarising elements, selective detection of light reflected on an object or light reflected by the support structure is enabled

Methodology Applied
Scientific EffectPolarisation: Polarisation

Data Source

PatentEP4560258A1Polarisation selective imaging
Publication Date: 2025.05.28 HEXAGON INNOVATION HUB GMBH
  • EP4560258A1 patent drawingFigure 1~2
  • EP4560258A1 patent drawingFigure 3~4b
  • EP4560258A1 patent drawingFigure 5a~6

AI summary

The invention relates to a measuring device for imaging an object (7). The measuring device comprises a light emitting unit (21) configured to emit polarised measuring light, a light receiving unit (30) configured to receive and detect reflected measuring light, and a support structure (10) which comprises a retro-reflective layer (11) and a polarisation state manipulation layer (12). The support structure (10) provides retro-reflecting of the measuring light and changing a polarisation state of the measuring light such that the polarisation state of incident measuring light is different relative to the polarisation state of retro-reflected measuring light. The measuring device (10) comprises a polarisation selecting unit configured to provide selecting either reflected measuring light with a first polarisation state or with a second polarisation state. The selection is provided by selectively providing emitting of the measuring light with a first polarisation state or with a second polarisation state by changing an emitting selection state of the polarisation selecting unit and/or by selectively providing transmitting of reflected measuring light only of the first polarisation state or of the second polarisation state by changing a transmission selection state of the polarisation selecting unit.