Front Window Light Barriers for Camera Sensor Crosstalk

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Solution Overview

Problem

Optical crosstalk occurs in camera-based sensors due to manufacturing-related inhomogeneities and contaminants on the front screen, leading to noise interference and reduced signal-to-noise ratio, particularly in time-of-flight methods.

Innovation Solution

Modify the windscreen material with laser-induced modifications, such as refractive index changes, nanogratings, and cavity channels, to form rectilinear or cylindrical structures that act as light barriers between transmission and reception light paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If additional mechanical separating components (separating bars, opaque tubes) are attached to the sensor to block transmitted light from reaching the receiver, then optical crosstalk is reduced, but device complexity and manufacturing complexity increase

Engineering Contradiction:
Improveoptical crosstalkVSAvoiddevice complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the light-blocking function into the front panel itself by creating optically modified regions directly within the panel material. These modified regions form light barriers that prevent transmitted light from reaching the receiver, eliminating the need for separate mechanical separating components while maintaining the crosstalk reduction function.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The front panel serves multiple functions: it protects the sensor interior, transmits received light to the receiver, and simultaneously blocks transmitted light from reaching the receiver through the optically modified regions. This multi-functionality eliminates the need for additional dedicated separating components.

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

2Object-affected harmful factors

If additional mechanical separating components are attached to the sensor, then optical crosstalk is reduced, but manufacturing complexity and production stability are impaired

Engineering Contradiction:
Improveoptical crosstalkVSAvoidmanufacturing complexity
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The light-blocking function is integrated into the front panel manufacturing process itself. The optically modified regions are created directly within the panel material using laser processing or other modification techniques, allowing the entire structure to be manufactured as a single integrated component rather than requiring assembly of multiple separate parts.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces mechanical separating components (physical bars, tubes, or webs attached to the sensor) with optically modified regions within the front panel material. This substitution transitions from a mechanical assembly approach to an integrated optical solution, simplifying manufacturing and improving production stability.

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

3Object-affected harmful factors

If the front panel material has very low surface roughness and is free of contaminants with constant refractive index, then optical crosstalk is reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improveoptical crosstalkVSAvoidmanufacturing precision
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

Instead of requiring the entire front panel to have perfectly uniform optical properties, the patent introduces optically modified regions with specifically tailored local properties. These modified regions have altered refractive indices or optical characteristics that enable them to function as light barriers, while the rest of the panel maintains its light-transmitting properties.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the optical parameters (refractive index, optical density) of specific regions within the front panel material through laser processing or other modification techniques. This allows creation of light-blocking regions without requiring changes to the overall manufacturing precision of the entire panel, as only localized parameter changes are needed.

Inventive Principle:
Principle #35Parameter changes

4Volume of moving object

If the sensor is miniaturized without additional separating components, then device size is reduced, but optical crosstalk increases due to shorter distances between transmitter and receiver

Engineering Contradiction:
Improvesensor sizeVSAvoidoptical crosstalk
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The light-blocking function is integrated into the front panel itself, allowing effective crosstalk prevention even in compact sensor designs. The optically modified regions within the panel provide sufficient light barrier functionality without requiring additional space for separate separating components, enabling sensor miniaturization while maintaining optical isolation.

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

Reduces optical crosstalk effectively, allowing for improved signal detection and miniaturization without additional components, enhancing the sensor's dynamic range and reducing manufacturing complexity.

Implementation Method 1

Modify the windscreen material with laser-induced modifications, such as refractive index changes, nanogratings, and cavity channels

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

refractive index changes

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 3

The transmitted light can be scattered and/or reflected by the front screen, causing the transmitted light to also reach the receiving module

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP4624085A1Light barrier inside a front window
Publication Date: 2025.10.01 SICK AG
  • EP4624085A1 patent drawingFigure 1
  • EP4624085A1 patent drawingFigure 2
  • EP4624085A1 patent drawingFigure 3

AI summary

Front screen for a camera-based sensor having a thickness (Z), width (Y) and length (X), wherein the front screen comprises a region with a plurality of modifications made of modified front screen material, wherein the modifications are arranged in sections to form modification structures.