Laser Medium Cooling Layout for Low Wavefront Distortion

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Solution Overview

Problem

High-quality laser beams are compromised by wavefront distortion due to heat in the laser medium, leading to increased beam spread and potential damage to optical devices, and existing cooling methods struggle to achieve a one-dimensional heat distribution for efficient cooling.

Innovation Solution

A laser apparatus with a laser medium having a first surface for incident laser light and a second surface for total reflection, where a cooling jet is injected directly onto the second surface, and an insulation layer with lower thermal conductivity covers areas not directly exposed to the jet, ensuring efficient cooling and minimizing heat distribution impact on wavefront distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a jet is injected to directly cool the laser medium surface, then cooling efficiency is improved, but in-plane cooling capacity control becomes difficult and heat distribution cannot be brought closer to one-dimensional distribution

Engineering Contradiction:
Improvecooling efficiencyVSAvoidcooling capacity control precision
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The patent applies local quality by creating distinct cooling zones on the laser medium surface. The jet is injected only at specific locations (e.g., center or selected areas) rather than uniformly across the entire surface. This localized cooling approach allows different regions of the laser medium to have different thermal characteristics, enabling precise control over the heat distribution pattern and achieving closer approximation to one-dimensional heat flow while maintaining high cooling efficiency.

Inventive Principle:
Principle #3Local quality

2Temperature

If the entire second surface is exposed to the jet for cooling, then cooling coverage is improved, but wavefront distortion due to heat cannot be minimized

Engineering Contradiction:
Improvecooling coverageVSAvoidwavefront distortion
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent implements local quality by selectively exposing only certain areas of the second surface to the jet while insulating other areas. This creates a controlled thermal gradient that promotes one-dimensional heat distribution from the pumped regions toward the cooled regions, thereby minimizing wavefront distortion caused by non-uniform heat distribution across the laser medium.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent introduces an insulation layer as an intermediary between the jet and portions of the laser medium surface. This insulation layer acts as a thermal barrier that prevents direct cooling in specific areas, allowing the jet to cool only designated regions. The insulation layer thus mediates the heat transfer process to achieve the desired one-dimensional heat distribution pattern.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If insulation layer is added to control heat distribution, then one-dimensional heat distribution is improved, but device complexity increases

Engineering Contradiction:
Improveheat distribution uniformityVSAvoidstructure complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent applies local quality by providing insulation only in specific areas where it is needed to control heat distribution, rather than insulating the entire surface. This selective insulation approach achieves the desired one-dimensional heat distribution while minimizing the addition of structural complexity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements partial action by applying the insulation layer only to the extent necessary to achieve one-dimensional heat distribution. Rather than fully insulating all surrounding areas, the insulation is applied selectively to the minimum required regions, thereby achieving the thermal control objective while keeping device complexity as low as possible.

Inventive Principle:
Principle #16Partial or excessive action

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 effectively reduces wavefront distortion by achieving a closer to one-dimensional heat distribution within the laser medium, enhancing the quality and focus of the laser beam while protecting optical devices from damage.

Implementation Method 1

a cooling device configured to cool the laser medium by directly injecting a jet toward at least a first area of the second surface

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

an insulation layer having a thermal conductivity lower than a thermal conductivity of the laser medium... configured to cover a second area of the second surface

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

the second surface is configured to totally reflect in the first area the incident laser light that is incident to the second surface at an incident angle equal to or larger than a critical angle

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3820004B1Laser device
Publication Date: 2024.04.24 MITSUBISHI HEAVY IND LTD
  • EP3820004B1 patent drawingFigure 1
  • EP3820004B1 patent drawingFigure 2A
  • EP3820004B1 patent drawingFigure 2B~2C

AI summary

A laser apparatus that can generate a high-quality laser beam is provided. The laser apparatus is provided with a laser medium and an insulation layer. The laser medium has a first surface and a second surface. Incident laser light is incident on the first surface. The second surface totally reflects the incident laser light that is incident to the second surface at an incident angle equal to or larger than a critical angle. The insulation layer covers a second area of the second surface that surrounds a first area of the second surface, the first area totally reflecting the incident laser light. The laser medium is exposed in the first area.