Beam-Shaping Element Assembly for Optical Stray Light Reduction

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Solution Overview

Problem

Existing optical devices, such as safety light barriers and laser scanners, face challenges in minimizing stray light interference, which can lead to inaccurate object detection and non-compliance with safety standards like EN ISO 13849-1, EN 61496-1, and EN 62046, due to reflections and scattering within the optical channel.

Innovation Solution

The integration of a jet-shaping element and a carrier made from materials with specific refractive indices, where the first material is permeable to electromagnetic radiation and the second material is absorptive, connected in a seamless manner to minimize reflection and refraction at the contact area, effectively reducing stray light through a defined refractive index ratio and absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If traditional light traps or filters are used to minimize stray light, then stray light reduction is achieved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvestray lightVSAvoiddevice complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the light-blocking function with the housing structure by making the absorptive material an integral part of the housing material itself, rather than adding separate light traps or filters. This is achieved by incorporating radiation-absorbing particles or additives into the housing material, creating a monolithic structure that performs both structural and stray light reduction functions simultaneously.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses composite materials by combining a base housing material with radiation-absorbing particles, additives, or layers. This creates a composite material with both structural properties and stray light absorption properties, eliminating the need for separate components while achieving effective stray light reduction.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If traditional light traps or filters are used to minimize stray light, then stray light reduction is achieved, but manufacturing cost increases

Engineering Contradiction:
Improvestray lightVSAvoidmanufacturing cost
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent combines the light-blocking function with the housing manufacturing process itself. By incorporating absorptive materials into the housing material or applying absorptive layers during housing fabrication, the stray light reduction function is integrated into the base manufacturing process, eliminating the need for separate assembly steps and reducing overall manufacturing cost.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent modifies the optical parameters of the housing material by adding radiation-absorbing particles, additives, or coatings. This changes the material's interaction with light from reflective/transmissive to absorptive, achieving stray light reduction through material parameter modification rather than adding complex optical components.

Inventive Principle:
Principle #35Parameter changes

3Strength

If contact surfaces between different materials are created in the optical channel, then structural assembly is enabled, but reflection and refraction at interfaces increase stray light

Engineering Contradiction:
Improvestructural assemblyVSAvoidstray light
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent extracts or eliminates the problematic air-gap interface between housing and mounting elements by making direct contact between solid materials. This removes the air-material boundaries that cause reflection and refraction, allowing structural assembly to proceed without creating stray light-generating interfaces.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates homogeneous material contact surfaces where housing material directly contacts mounting element material, eliminating heterogeneous interfaces (such as air gaps) that cause optical disturbances. This direct solid-to-solid contact maintains structural integrity while minimizing stray light through uniform material properties at the interface.

Inventive Principle:
Principle #33Homogeneity

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 solution significantly reduces stray light effects, enhancing the accuracy of optical devices while meeting safety standards by ensuring that incident light is absorbed rather than reflected or refracted, thus improving detection reliability and cost-effectiveness in production.

Implementation Method 1

the second material is absorptive for the defined electromagnetic radiation

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

The first material and the second material each have a defined refractive index with respect to the defined electromagnetic radiation. The defined refractive index of the second material is set in a defined ratio to the defined refractive index of the first material in order to establish a specific transition characteristic for the defined electromagnetic radiation at the contact surface.

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP4506737A1Optical apparatus with stray light reduction
Publication Date: 2025.02.12 PILZ GMBH & CO KG
  • EP4506737A1 patent drawingFigure 1
  • EP4506737A1 patent drawingFigure 2
  • EP4506737A1 patent drawingFigure 3

AI summary

Optical device (10) comprising: a beam-shaping element (12) made of a first material with a base (20) and a top surface (22) facing each other, and with a surrounding lateral surface (24) connecting the base (20) and the top surface (22); and a support (14) made of a second material, which is formed with a receptacle (18) for the beam-shaping element (18) and has at least one common contact surface (26) with the lateral surface (24) of the beam-shaping element (12). At the contact surface (26) between the beam-shaping element (12) and the support (14), the first material and the second material are in direct contact with each other. The first material is transparent to a defined electromagnetic radiation and the second material is absorbent to the defined electromagnetic radiation.Furthermore, the first material and the second material each have a defined refractive index (n1, n2) with respect to the defined electromagnetic radiation. The defined refractive index (n2) of the second material is set in a defined ratio to the defined refractive index (n1) of the first material in order to establish a specific transition characteristic for the defined electromagnetic radiation at the contact surface (26).