Laser Source Angular Scanning Phase Modulation

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Solution Overview

Problem

Existing coherent laser sources with mechanical scanning systems face challenges in achieving high resolution and robustness, especially in vibratory environments, and non-mechanical deflection solutions have limitations in resolution and energy concentration for high deflection angles.

Innovation Solution

A laser device with two angular deflection systems, where the first system uses phase shifters controlled by a phase servo device for initial deflection, and a second system with movable collimating optical subsystems on a common mechanical structure for additional deflection, allowing significant angular deviation without mechanical displacement, and optimizing energy concentration in a central lobe.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If mechanical scanning systems (galvanometric mirrors) are used, then scanning speed and field angle are improved, but reliability and robustness deteriorate in vibratory environments

Engineering Contradiction:
Improvescanning speedVSAvoidreliability in vibratory environments
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent replaces the mechanical galvanometric mirror system with a non-mechanical phase modulation system. Multiple laser beams are generated and their phases are independently modulated to achieve beam deflection without mechanical moving parts, thereby eliminating reliability issues in vibratory environments while maintaining scanning functionality

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

Solution Approach 2:

The patent divides a single laser beam into multiple elementary beams (e.g., 3x3 array = 9 beams). Each beam is independently phase-modulated to create a composite beam pattern that can be dynamically steered. This segmentation allows electronic control of beam direction without mechanical components

Inventive Principle:
Principle #1Segmentation

2Reliability

If non-mechanical phase modulation is used, then reliability is improved, but deflection resolution and energy concentration deteriorate for large deflection angles

Engineering Contradiction:
ImproverobustnessVSAvoiddeflection resolution
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent merges multiple elementary beams into a single composite beam through coherent combination. The phase modulation of individual beams is coordinated to constructively interfere in the desired deflection direction, achieving both high resolution and energy concentration without mechanical parts

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent dynamically changes the phase parameters of multiple elementary beams to control the deflection angle and resolution. By adjusting phase differences between beams, the system achieves precise angular control and maintains energy concentration across different deflection angles

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If single fiber laser source is used, then simplicity is improved, but power output deteriorates due to flux resistance limitations

Engineering Contradiction:
ImprovesimplicityVSAvoidpower output
Core Design Contradiction:
Device complexityVSPower

Solution Approach 1:

The patent segments the laser source into multiple independent fiber lasers (e.g., 9 fibers in a 3x3 array). Each fiber operates independently within its power and flux resistance limits, but their combined output through coherent beam combination achieves total power levels unattainable by a single fiber

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates a composite laser source by combining multiple fiber laser outputs. The coherent combination of multiple beams produces a composite beam with power and luminance exceeding the capabilities of individual fibers, while maintaining the simplicity and robustness of fiber laser technology

Inventive Principle:
Principle #40Composite materials

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 configuration significantly increases deflection resolution and maintains precise pointing, achieving large deflection angles with concentrated energy in a central lobe, suitable for applications requiring high scanning precision and robustness.

Implementation Method 1

N phase shifters controlled by a phase servo device, each phase shifter being associated with one of said elementary sub-beams and arranged so as to introduce a controlled phase shift on said sub-beam

Methodology Applied
Scientific EffectPhase shift: Phase Modulation

Implementation Method 2

a second angular deflection system arranged in series with the first angular deflection system on the same optical axis and consisting of N identical collimating optical sub-systems mounted on a common mechanical structure, the structure being movable in translation in a plane substantially perpendicular to the common optical axis of the beams

Methodology Applied
Scientific EffectOptical deflection: Lens

Implementation Method 3

an optical assembly made up of N fixed focusing optical subsystems, each collimating optical subsystem being arranged in front of an optical collimating subsystem, each optical focusing subsystem being arranged so as to focus the associated sub-beam on the field optics

Methodology Applied
Scientific EffectFocusing: Focusing

Implementation Method 4

Coherent recombination of laser beams is a technique used to address the problem of limiting the flux resistance of gain materials, with the aim of obtaining a high-power laser source. The N incident laser beams are single-mode spatial beams of the same polarization. A coherent recombination system receives a beam composed of N laser sub-beams, obtained at the output of the N propagation paths. It provides a recombinant laser beam as output.

Methodology Applied
Scientific EffectCoherent recombination: Interference

Data Source

PatentEP2206011B1Laser source comprising an angular scanning device
Publication Date: 2011.04.13 THALES SA
  • EP2206011B1 patent drawingFigure 1~2
  • EP2206011B1 patent drawingFigure 3
  • EP2206011B1 patent drawingFigure 4

AI summary

The invention generally pertains to the field of laser scanning devices including a coherent laser source emitting N elementary sub-beams and a first angular deflection system (1) including N phase shifters controlled by a phase lock device (3). The device of the invention includes a second angular deflection system (4) arranged in series with the first angular deflection system on the same optical axis, and including N identical collimation optical sub-systems mounted on a common mechanical structure, each sub-system being provided in front of one of said elementary sub-beams, and the structure being capable of a translation movement in a plane substantially perpendicular to the common optical axis of the beams so that the translation of the structure results in a simultaneous deflection of the N elementary sub-beams, the second deflection angle being added to the first deflection angle.