Coaxial Laser Beam Combining for Compact High-Power Focusing

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Solution Overview

Problem

Existing methods for combining laser beams to achieve high power face challenges such as increased physical size, weight, and reduced light-condensing ability, with limitations on the number and power of laser beams due to the use of diffractive optical elements.

Innovation Solution

A laser beam irradiation apparatus that overlaps and expands laser beams to minimize beam diameters on a target face, using phase control devices and beam shaping optics to optimize wave fronts, without relying on special optical elements like diffractive gratings, thereby combining multiple laser beams to generate high-power synthesized beams.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the number of laser beams is increased to achieve high power, then the power output is improved, but the physical size and weight of the irradiation apparatus increase

Engineering Contradiction:
Improvepower outputVSAvoidweight of irradiation apparatus
Core Design Contradiction:
PowerVSWeight of stationary object

Solution Approach 1:

Multiple laser beams are combined coaxially within the irradiation apparatus using a beam combining optics system, merging their optical paths so they all emit from the same position. This allows high power output from multiple beams without increasing the physical size or weight of the apparatus, as the combined beams share common optical components and emission path.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions from spatial combination (side-by-side beam arrangement) to spectral/wavelength-based combination, where beams with slightly different wavelengths are combined coaxially. This dimensional shift in the combination approach allows multiple high-power beams to occupy the same spatial path without physical interference, avoiding weight and size increases.

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

2Power

If the number of laser beams is increased for a fixed physical size, then the power output is improved, but the beam diameters are reduced causing deterioration in light-condensing ability

Engineering Contradiction:
Improvepower outputVSAvoidlight-condensing ability
Core Design Contradiction:
PowerVSManufacturing precision

Solution Approach 1:

The beam combining optics system merges multiple laser beams coaxially, allowing each beam to maintain its full diameter up to the lens barrel diameter. By combining them along the same optical axis rather than arranging them side-by-side, each beam preserves its light-condensing ability while contributing to high total power output.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system uses beams with slightly different wavelengths and employs wavelength-dependent optical elements to combine them. By changing the wavelength parameter and using dispersive optics, multiple beams can be superimposed coaxially without interfering with each other's beam quality or condensing ability, allowing high power with maintained precision.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If diffractive optical elements are used for spectrum combination, then laser beam combination is achieved, but the number and power of laser beams are limited due to power tolerance constraints

Engineering Contradiction:
Improvebeam combination capabilityVSAvoidpower tolerance
Core Design Contradiction:
Adaptability or versatilityVSPower

Solution Approach 1:

The patent extracts the wavelength-dependent optical elements from the diffractive grating category and uses alternative elements such as prisms or refractive optics that can handle higher laser powers. This removes the power tolerance limitation while maintaining the spectral combination capability, allowing combination of higher-power beams.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using a single diffractive grating with limited power tolerance, the system uses multiple wavelength-dependent optical elements or a configured optical system that replicates the spectral separation function but with higher power handling capability, effectively copying the combination function with improved power tolerance.

Inventive Principle:
Principle #26Copying

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 apparatus achieves high-power laser beam synthesis while maintaining a compact size and improving light-condensing ability, allowing for efficient and effective laser beam combination.

Implementation Method 1

a light-condensing optics system configured to perform an optical operation on a plurality of first laser beams made incident thereon to emit a plurality of second laser beams

Methodology Applied
Scientific EffectOptical operation: Lens

Implementation Method 2

the light-condensing optics system is configured so that beam diameters of all the second laser beams emitted from the light-condensing optics system are minimal on a target face

Methodology Applied
Scientific EffectBeam condensing: Focusing

Implementation Method 3

the plurality of laser light sources respectively comprise phase control devices controlling phases of the first laser beams emitted therefrom

Methodology Applied
Scientific EffectPhase control: Phase Modulation

Data Source

PatentEP3641080B1Laser beam irradiation device and laser beam irradiation system
Publication Date: 2025.08.20 MITSUBISHI HEAVY IND LTD
  • EP3641080B1 patent drawingFigure 1
  • EP3641080B1 patent drawingFigure 2A
  • EP3641080B1 patent drawingFigure 2B

AI summary

A laser beam irradiation apparatus comprises: a plurality of laser light sources emitting first laser beams, respectively; and a light-condensing optics system comprising an incident face on which the first laser beams are made incident and performing an optical operation on the first laser beams to emit second laser beams associated with the first laser beams, respectively. The plurality of laser light sources are configured to emit the first laser beams so that beam diameters of the first laser beams are expanded towards the incident face. Each of the first laser beams overlaps at least one of the other laser beams on the incident face of the light-condensing optics system. The light-condensing optics system is configured so that beam diameters of all the second laser beams emitted from the light-condensing optics system are minimal on a target face, and a distance between a center of each of the second laser beams and the optical axis on the target face is smaller than a beam radius of each of the second laser beams on the target face. A high-power synthesized laser beam is obtained by combining a plurality of laser beams.