Optical Beam Splitting for Eye-Safe Long-Range Wireless Links

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Solution Overview

Problem

Existing optical wireless communication systems face limitations in achieving high data rates and ranges while ensuring eye safety, as conventional methods either restrict transmission power for safety or suffer from inefficient light distribution, leading to reduced communication effectiveness.

Innovation Solution

The use of separation optics to spatially divide optical signals into multiple sub-signals focused on different locations, allowing for high transmission power without eye damage by ensuring each focal point meets safety standards, thereby enhancing communication range and data rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If laser power is increased to improve transmission distance and data rate, then communication range and signal-to-noise ratio are improved, but eye safety is compromised

Engineering Contradiction:
Improvecommunication rangeVSAvoideye safety
Core Design Contradiction:
Length of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies segmentation by dividing a single high-power laser beam into multiple lower-power sub-beams using beam splitting optics. This allows the total optical power to be maintained for extended communication range while each individual sub-beam remains below eye safety thresholds. The laser output is optically divided into N sub-beams with reduced power density, achieving both long range and safety compliance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-dimensional high-power beam to a multi-dimensional array of lower-power beams. By spatially distributing the optical power across multiple beams in different directions, the system maintains total power for range while reducing power density in each direction to safe levels, effectively adding a spatial distribution dimension to the transmission.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If laser power is restricted to ensure eye safety, then eye safety is maintained, but transmission distance and data rate are reduced

Engineering Contradiction:
Improveeye safetyVSAvoidcommunication range
Core Design Contradiction:
Object-affected harmful factorsVSLength of stationary object

Solution Approach 1:

The patent segments the safety-compliant low-power constraint into multiple beams, where each beam individually meets eye safety standards. By combining multiple such beams, the system achieves aggregate power levels sufficient for long-range communication while maintaining safety compliance at each beam level.

Inventive Principle:
Principle #1Segmentation

3Object-affected harmful factors

If a diffuser is used to scatter light for eye safety, then eye safety is improved, but light distribution efficiency deteriorates

Engineering Contradiction:
Improveeye safetyVSAvoidlight output efficiency
Core Design Contradiction:
Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

Instead of using a diffuser that randomly scatters light, the patent employs precise optical beam splitting to create N controlled sub-beams. This segmented approach maintains directional efficiency for communication while achieving eye safety through spatial distribution, avoiding the random scattering losses inherent in diffuser-based solutions.

Inventive Principle:
Principle #1Segmentation

4Power

If multiple laser sources are used to distribute power, then transmission power and range are improved, but device complexity increases

Engineering Contradiction:
Improvetransmission powerVSAvoidsystem structure
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent segments a single laser source into multiple beams using optical splitting components, achieving the power distribution benefits of multiple sources while maintaining a single laser unit. This reduces complexity compared to using N separate laser sources, while still providing the necessary power distribution for extended range and safety compliance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines multiple beam paths into a single laser source system, integrating the functions of what would otherwise require multiple independent laser units. The beam splitting and recombination optics unify the system architecture, reducing overall complexity while maintaining the power distribution capabilities.

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 enables high-power optical communication with extended range and improved signal-to-noise ratio by distributing light safely across disjoint focal points, reducing losses and enabling higher permissible light powers.

Implementation Method 1

separation optics configured to spatially divide the optical signal into a plurality of optical sub-signals

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

the majority of optical partial signals are focused at spatially disjoint locations of an image plane when focusing together

Methodology Applied
Scientific EffectFocusing: Focusing

Data Source

PatentEP4150792B1Eye-safe optical wireless communication
Publication Date: 2025.10.08 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP4150792B1 patent drawingFigure 1
  • EP4150792B1 patent drawingFigure 2a
  • EP4150792B1 patent drawingFigure 2b

AI summary

A communication node for optical wireless communication in an optical wireless communication network has the following: an input interface designed to receive a data signal, an optical transmitter designed to convert the data signal into an optical signal having an optical power, separating optics designed to spatially divide the optical signal into a plurality of optical component signals having an associated spectral range, in order to split the optical power over the plurality of optical component signals, at least some of the plurality of spectral ranges being concordant. The communication node is designed to transmit the plurality of optical component signals for the optical wireless communication.