Multi-Wavelength Laser Amplifier Layout for Low-Loss Beam Parallelism

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Solution Overview

Problem

Current laser amplification devices cooled from the rear face suffer from geometric beam folding and temporal contrast degradation due to parasitic reflections, which leads to optical losses and increased maintenance costs, especially when using multiple optics to compensate for prismatic effects.

Innovation Solution

A multi-wavelength laser amplification device with two solid amplifying media having inclined front and rear faces, where the second medium is arranged to receive the beam reflected by the first medium, ensuring sub-beams of each wavelength are parallel, and additional amplifying media are used to compensate for beam widening without introducing additional losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the front face of the amplifying medium is inclined relative to the rear face to separate parasitic reflections from the main pulse, then temporal contrast is improved, but optical losses increase due to the need for multiple compensation prisms

Engineering Contradiction:
Improvetemporal contrastVSAvoidoptical losses
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The patent extracts the harmful parasitic reflections from the main optical path by using the inclined front face to spatially separate them from the main pulse. This extraction allows the main beam to be amplified without being contaminated by parasitic pulses, thereby improving temporal contrast while minimizing the need for additional optical compensation elements that would cause losses.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces asymmetry by inclining the front face of the amplifying medium relative to the rear face at a non-zero angle. This asymmetric configuration causes parasitic reflections to diverge from the main beam path, achieving spatial separation that improves temporal contrast without requiring symmetric compensation prisms that would introduce optical losses.

Inventive Principle:
Principle #4Asymmetry

2Shape

If multiple compensation prisms are implemented to correct the prismatic effect, then beam quality is maintained, but device complexity and maintenance requirements increase

Engineering Contradiction:
Improvebeam qualityVSAvoidnumber of optics
Core Design Contradiction:
ShapeVSDevice complexity

Solution Approach 1:

The patent converts the harmful prismatic effect caused by the inclined front face into a beneficial spatial separation mechanism. The same inclination that causes beam deviation is used to separate parasitic reflections from the main pulse, turning a potential source of beam quality degradation into a tool for improving temporal contrast and reducing the need for additional compensation optics.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Temperature

If the amplifying medium is cooled from the rear face to achieve high thermal extraction, then thermal management is improved, but geometric beam folding occurs due to the reflective back face

Engineering Contradiction:
Improvethermal extractionVSAvoidbeam path
Core Design Contradiction:
TemperatureVSShape

Solution Approach 1:

The patent addresses the beam path distortion caused by rear-face cooling by using the inclined front face to compensate for the geometric folding in a different dimensional approach. The inclination angle is designed to counteract the beam deviation introduced by the reflective rear face, effectively correcting the beam path in the spatial domain while maintaining efficient thermal extraction through the rear face.

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

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 solution minimizes optical losses while maintaining satisfactory cooling and temporal contrast, allowing for efficient amplification of high-energy, high-average-power laser beams with improved thermal management and reduced maintenance needs.

Implementation Method 1

a first solid amplifying medium having a first refractive index, the first amplifying medium having at least two flat faces among a front face suitable for receiving the beam to be amplified, called the incident beam

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

a reflective rear face, the front face being inclined relative to the rear face by a first non-zero inclination

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

the rear face (being suitable for being cooled

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4264753B1Laser beam amplification device
Publication Date: 2025.01.01 THALES SA
  • EP4264753B1 patent drawingFigure 1
  • EP4264753B1 patent drawingFigure 2
  • EP4264753B1 patent drawingFigure 3

AI summary

The present invention relates to a device (10) for amplifying a multi-wavelength laser beam, comprising: a. a first amplifying medium (M1) having a front face (20) and a reflecting rear face (22), which faces are tilted relative to each other by a first non-zero tilt, and b. a second amplifying medium (M2) having a front face (20) capable of receiving the beam (FR1) reflected by the rear face (22) and refracted by the front face (20) of the first amplifying medium (M1), and a reflecting rear face (22), which faces are tilted relative to each other by a second non-zero tilt, the first tilt, the second tilt and the orientation of the second amplifying medium (M2) being such that the sub-beams of each wavelength, which form the output beam (FR2) of the second amplifying medium (M2), are parallel to each other at the output of the second amplifying medium (M2).