Laser Beam Splitting Layout for Collimated AOM Beam Matrices

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Solution Overview

Problem

Existing laser material processing systems face limitations in efficiently utilizing high laser power due to beam divergence and the need for large, expensive optics, which affect switching speed and diffraction efficiency in acousto-optic modulators, especially when generating two-dimensional beam matrices.

Innovation Solution

A laser material processing arrangement that uses prisms for beam parallelization in one dimension and a combination of prisms and telescopes in the other dimension to maintain collimation, along with dynamic beam deflection, allowing independent switching of individual beams and reducing the size of optical elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If relay optics with intermediate focus are used to parallelize beams, then beam parallelization is achieved, but beam divergence occurs in the acousto-optic modulator reducing diffraction efficiency and increasing switching time

Engineering Contradiction:
Improvebeam parallelizationVSAvoidswitching speed and diffraction efficiency
Core Design Contradiction:
Stability of the object's compositionVSProductivity

Solution Approach 1:

The invention removes the intermediate focus element from the optical path. By using a telescope system (objective lens and eyepiece lens) instead of relay optics with intermediate focus, the beam is parallelized without creating a focus point where divergence would occur. This extraction of the problematic intermediate focus resolves the contradiction between achieving beam parallelization and maintaining beam quality for high-speed switching.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The telescope system acts as an intermediary between the beam splitting device and the acousto-optic modulator. The objective lens creates a focus that is immediately re-collimated by the eyepiece lens, providing beam parallelization without the harmful intermediate focus that causes divergence. This intermediary optical system maintains beam collimation while achieving the desired parallelization.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If multiple multi-channel acousto-optic modulators are used to generate two-dimensional beam matrices, then independent beam switching is achieved, but the optics become very wide requiring large expensive lenses

Engineering Contradiction:
Improveindependent beam switching capabilityVSAvoidoptical system width
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The invention merges the beam parallelization function and the beam combining function into a single telescope system. The objective lens and eyepiece lens work together to both parallelize the beams from the beam splitting device and combine them into a compact two-dimensional matrix. This consolidation eliminates the need for multiple separate multi-channel AOMs and their associated wide optics, achieving independent beam switching with a compact optical layout.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The telescope system transforms the spatial arrangement of beams by using optical magnification and demagnification. The beam matrix is formed in a compact configuration by leveraging the telescopic ratio, effectively compressing the optical path in one dimension while maintaining the two-dimensional switching capability. This dimensional transformation allows compact optics to achieve the same functional result as much larger optical systems.

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

3Productivity

If beam diameter is reduced to improve AOM performance, then switching speed and diffraction efficiency improve, but the beam power is reduced

Engineering Contradiction:
Improveswitching speed and diffraction efficiencyVSAvoidbeam power
Core Design Contradiction:
ProductivityVSPower

Solution Approach 1:

The telescope system enables independent control of beam diameter and beam power parameters. By adjusting the telescopic ratio and the positioning of lenses, the system can optimize the beam diameter for high diffraction efficiency in the AOM while the overall beam power is maintained through the optical design. The parameter optimization is achieved without the trade-off that would exist in a simple system, as the telescope allows decoupling of these two parameters.

Inventive Principle:
Principle #35Parameter changes

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

Enables efficient use of high laser power with compact optics, enhancing productivity and flexibility in surface structuring applications by maintaining beam collimation and reducing switching time.

Implementation Method 1

the first optical arrangement comprises several prisms designed and arranged such that, as the partial beams pass through the prisms, they align them parallel to each other in the first dimension by means of double refraction (at the entrance and exit surfaces of the prism)

Methodology Applied
Scientific EffectDouble refraction: Refraction

Implementation Method 2

The modulation device following the first optical arrangement comprises several acousto-optic modulators, which are multi-channel in the first dimension and with which the individual partial beams can be modulated independently of one another

Methodology Applied
Scientific EffectAcousto-optic modulation: Acousto-optic Effect

Implementation Method 3

With the dynamic beam deflection device, e.g., a 2D galvanometer scanner, the partial beams are then dynamically deflected in two perpendicular directions and guided over a processing plane

Methodology Applied
Scientific EffectBeam deflection: Reflection

Data Source

PatentEP4281244B1Arrangement for laser material processing
Publication Date: 2026.04.08 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP4281244B1 patent drawingFigure 1a~2b
  • EP4281244B1 patent drawingFigure 3a~4b
  • EP4281244B1 patent drawingFigure 5~6

AI summary

The invention relates to a laser material machining assembly having at least one laser beam source (5), a beam splitter (6), a modulating device with a plurality of acousto-optical modulators (4), and a dynamic beam deflecting device (9). A collimated laser beam (10) is separated two-dimensionally into a plurality of sub-beams (1) by means of the beam splitter (6), said sub-beams running non-parallel to one another in at least one first dimension. An optical assembly is arranged between the beam splitter (6) and the modulating device in order to parallelize the sub-beams (1) in the first dimension. The optical assembly has an array of multiple prisms (12) which are designed and arranged such that the sub-beams (1) are aligned in parallel to one another in the first dimension upon passing through the prisms (12) by means of a respective double refraction. In this manner, the sub-beams (1) remain collimated in the acousto-optical modulators (4) so that the modulation can be carried out in the acousto-optical modulators (4) with maximum efficiency. The assembly can thus also be provided in a compact design.