FSO Terminal Optical Layout for Lightweight Vibration Compensation

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Solution Overview

Problem

Existing free-space optical (FSO) communications terminals are bulky, heavy, and require significant power due to the use of optical elements in each arm for beam focusing and collimation, which limits their practical applications, especially in vehicles prone to vibrations.

Innovation Solution

A FSO terminal design that incorporates a beamsplitter with a third arm containing an optical element for shared collimation and focusing functions, reducing the need for optical elements in each arm, and employs a pellicle beamsplitter with an auxiliary beam position tracking detector to compensate for vibrations, ensuring accurate beam steering and improved coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical elements are placed in each arm for beam focusing and collimation, then beam quality and transmission accuracy are improved, but device weight and size increase

Engineering Contradiction:
Improvebeam qualityVSAvoidterminal weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent combines the optical elements from multiple arms into a single shared optical element positioned at the focal point of the beamsplitter. This single element performs collimation for transmitted beams and focusing for received beams across all arms simultaneously, reducing the total number of optical components and their associated weights while maintaining beam quality through the beamsplitter's optical path design

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The shared optical element serves multiple functions: it collimates transmitted beams from different arms, focuses received beams from different arms, and works in conjunction with the beamsplitter to handle both transmission and reception paths. This multi-functional design eliminates the need for separate optical elements in each arm, reducing overall device weight and size

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

2Reliability

If optical elements are placed in each arm for beam focusing and collimation, then beam transmission accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvebeam transmission accuracyVSAvoidterminal complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple optical paths into a unified system where a single optical element serves all arms through the beamsplitter. This consolidation reduces the number of components that need to be aligned, calibrated, and maintained, thereby reducing system complexity while preserving transmission accuracy through the coordinated optical paths of the beamsplitter and shared element

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The shared optical element provides universal service to all arms for both transmission and reception functions. This universal design simplifies the system architecture by eliminating redundant components and reducing the complexity of optical path management, while the beamsplitter ensures accurate beam routing to maintain transmission precision

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

3Weight of moving object

If a pellicle beamsplitter is used to reduce weight and size, then device portability is improved, but vibration sensitivity increases

Engineering Contradiction:
Improveterminal weightVSAvoidvibration resistance
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The patent incorporates a vibration sensor that continuously monitors the pellicle beamsplitter's position and provides feedback to a control system. When vibrations are detected, the system generates compensation signals that adjust the optical paths or beam steering mechanisms to counteract the vibration effects, maintaining beam alignment and transmission reliability despite the lightweight pellicle structure's vulnerability to vibrations

Inventive Principle:
Principle #23Feedback

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

The design achieves a more compact, lightweight terminal with enhanced beam quality and data transmission rates by minimizing aberrations and compensating for vibrations, improving fuel efficiency and handling in vehicles.

Implementation Method 1

the optical element configured to collimate the diverging first transmitted beam and/or the diverging second transmitted beam incident thereupon so as to provide a collimated transmitted beam to the pointing unit

Methodology Applied
Scientific EffectCollimation: Lens

Implementation Method 2

focus the first and/or second received beam from the pointing unit so as to provide a converging beam to the first arm and/or second arm

Methodology Applied
Scientific EffectFocusing: Lens

Implementation Method 3

a beamsplitter having a first, second, and third port; a first arm addressing the first port of the beamsplitter... a second arm addressing the second port of the beamsplitter

Methodology Applied
Scientific EffectBeam splitting: Reflection

Data Source

PatentEP4712365A1Free space optical communications terminal
Publication Date: 2026.03.18 AIRBUS OPERATIONS LTD
  • EP4712365A1 patent drawingFigure 1~2
  • EP4712365A1 patent drawingFigure 3~4
  • EP4712365A1 patent drawingFigure 5~6

AI summary

Disclosed is a free-space optical communications (FSO) terminal comprising: a first arm addressing a first port of a beamsplitter and comprising a first component configured to transmit a diverging first transmitted beam and/or utilise a first received beam; a second arm addressing a second port of the beamsplitter and comprising a second component configured to transmit a diverging second transmitted beam and/or utilise a second received beam; and a third arm addressing the third port of the beamsplitter and comprising a pointing unit configured to steer the first and/or second transmitted beam to a target and/or the first and/or second received beam received from a target. The third arm comprises an optical element to collimate transmitted beams to provide a collimated transmitted beam to the pointing unit, and focus received beams so as to provide a converging beam to the first/second arm. A method of beam steering is also disclosed.