Air-Cooled CO2 Laser Thermal Management

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Solution Overview

Problem

CO2 lasers experience a pointing-stabilization period due to temperature changes during warm-up, affecting beam precision in hole-drilling operations, leading to lost production time.

Innovation Solution

A CO2 laser design with an elongated cooling unit featuring a plurality of spaced-apart fins and strategically placed fans to enhance air flow, minimizing thermal expansion and beam pointing instability, achieved by optimizing the placement and construction of the resonator and power-supply units with a central cooling unit and matching materials to reduce differential expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the laser is operated in a pulsed manner with galvanometer mirrors for beam steering, then precision hole-drilling is achieved, but beam pointing stability deteriorates during warm-up period due to temperature changes

Engineering Contradiction:
Improvehole-drilling precisionVSAvoidbeam pointing stability
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent changes the thermal parameters of the laser system by introducing active cooling mechanisms and thermally conductive materials. The cooling system maintains the laser resonator at a stable temperature, preventing thermal expansion that would cause beam pointing drift. This allows the laser to achieve stable operation immediately upon startup without requiring a warm-up period.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary cooling action to counteract the expected thermal expansion before it can affect beam pointing. The cooling system is designed to preemptively remove heat from the resonator and surrounding components, preventing the temperature rise that would otherwise cause mechanical expansion and beam direction changes during the warm-up period.

Inventive Principle:
Principle #9Preliminary anti-action

2Productivity

If the laser operates without a stabilization period, then production time is increased, but beam pointing precision deteriorates due to thermal expansion

Engineering Contradiction:
Improveproduction efficiencyVSAvoidbeam pointing precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent fundamentally changes the thermal parameter profile of the laser system by implementing active temperature control. The cooling system maintains the resonator temperature within a narrow range, ensuring that beam pointing remains stable regardless of operating duration. This eliminates the need for a warm-up stabilization period while maintaining precision hole-drilling capability throughout operation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the passive mechanical warm-up stabilization process with an active thermal control system. Instead of relying on natural thermal equilibrium that requires time, the system uses forced convection cooling and thermally conductive materials to actively maintain stable temperatures, substituting the time-dependent mechanical stabilization with an controlled thermal management approach.

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

3Device complexity

If conventional cooling arrangements are used, then device complexity is reduced, but temperature stabilization deteriorates leading to beam pointing drift

Engineering Contradiction:
Improvecooling system complexityVSAvoidtemperature stability
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The patent applies local quality enhancement by focusing cooling capacity specifically at the laser resonator and surrounding components that generate heat and affect beam pointing. The cooling system is strategically positioned to provide intensive cooling where needed rather than uniform cooling throughout the entire device, improving temperature stability with minimal additional complexity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs asymmetric cooling design where the cooling system is positioned and configured to address the specific thermal distribution pattern of the laser components. The cooling channels and heat sinks are strategically placed on the heat-generating sides of the resonator and power supply, creating an asymmetric but highly effective thermal management solution that targets the actual heat sources.

Inventive Principle:
Principle #4Asymmetry

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 significantly reduces or eliminates the pointing-stabilization period, ensuring consistent beam steering and increased production efficiency by maintaining precise beam direction without the need for extended warm-up times.

Implementation Method 1

a cooling unit (26) positioned between the resonator unit and the power supply unit, the cooling unit including a plurality of fins (28) and a plurality of fans (30) arranged to drive air through the fins

Methodology Applied
Scientific EffectForced convection: Forced Convection

Implementation Method 2

the output-beam direction, referred to as 'pointing' by practitioners of the art changes progressively. This is due to rising of the temperature of the laser

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3284148B1Air-cooled carbon-dioxide laser
Publication Date: 2021.10.20 COHERENT INC
  • EP3284148B1 patent drawingFigure 1
  • EP3284148B1 patent drawingFigure 1A
  • EP3284148B1 patent drawingFigure 1B

AI summary

A carbon dioxide waveguide-laser includes an elongated resonator unit and an elongated RF power-supply unit. The resonator and RF power-supply units are spaced by a air cooling unit including a plurality of longitudinally extending, spaced-apart fins, with fans arranged to drive air through the spaces between the fins.