Laser Beam Shaping via Partial Beam Segmentation
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Solution Overview
Problem
Diffractive diffuser algorithms used in beam shaping for laser material processing often result in undesired interference between adjacent diffraction orders, leading to speckle patterns that negatively impact processing quality.
Innovation Solution
The method involves dividing the laser beam into multiple partial beams with different properties such as polarization, wavelength, or temporal delay, ensuring that adjacent intensity maxima differ in these properties to prevent interference, and using beam shapers and spatial light modulators to control the intensity profiles and phase masks for optimal beam shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If diffractive diffuser algorithms are used for beam shaping, then beam intensity distribution can be controlled, but speckle patterns and interference occur between adjacent diffraction orders
Solution Approach 1:
The laser beam is divided into multiple partial beams by a beam splitter, where each partial beam is shaped independently by separate beam shapers. This segmentation allows independent control of each partial beam's intensity profile while preventing interference between adjacent diffraction orders through different polarization states or temporal delays.
Solution Approach 2:
The invention changes key parameters of the partial beams including polarization state (using wave plates to create orthogonal polarizations), wavelength (using acoustic-optic tunable filters to create different wavelengths), and temporal delay (using delay units to separate arrival times). These parameter changes ensure that adjacent diffraction orders do not interfere while maintaining precise intensity distribution control.
2Object-generated harmful factors
If beam splitting is used to avoid interference, then speckle patterns are reduced, but system complexity increases
Solution Approach 1:
Multiple partial beams with different properties (polarization, wavelength, or temporal delay) are combined using a beam combiner to form a single output beam. This merging approach maintains the interference-preventing benefits of beam splitting while consolidating the beams into one unified output for processing.
Solution Approach 2:
The invention introduces intermediary optical elements including wave plates for polarization control, acoustic-optic tunable filters for wavelength differentiation, and delay units for temporal separation. These intermediaries enable precise control of partial beam properties while managing the complexity through standardized optical components.
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 approach significantly reduces speckle patterns and improves beam quality by ensuring that adjacent diffraction orders do not interfere, resulting in a more uniform and precise intensity distribution in the processing plane.
Implementation Method 1
the laser beam is divided into at least two partial or individual beams by means of at least one beam splitter
Implementation Method 2
In order to be able to shape the intensity distribution of a laser beam, either its phase, its amplitude or both must be modulated together
Implementation Method 3
The phase modulators, in turn, are based on two different principles - the principle of refraction (refraction) and the principle of diffraction (diffraction)
Implementation Method 4
Diffractive beam shapers are mostly 1D or 2D array structures that apply a discretized phase delay (phase distribution) to the incident (unshaped) laser beam
Implementation Method 5
Changing the phase distribution of the incident laser beam also changes its intensity distribution in the Fourier plane (focus plane)
Implementation Method 6
adjacent intensity maxima of the intensity profile of the output beam differing in at least one or more light properties to exclude the formation of interference
Data Source
Figure 1~2b
Figure 3a~4
Figure 5~6
AI summary
The invention relates to a method and a laser assembly for material processing, wherein, in a laser assembly, a laser beam is focused onto a processing/imaging plane and the laser beam can be adapted in terms of its intensity distribution by means of at least one beam shaper. In addition, in order to prevent uniformity errors in the processing/imaging plane the laser beam is divided into at least two sub- or individual beams by means of at least one beam divider, and the sub- or individual beams are differently influenced or each sub- or individual beam is formed from a laser source with different wavelengths in such a way that they form an output beam with an intensity profile after the aggregation and focusing thereof onto the processing/imaging plane, wherein neighbouring intensity maxima of the intensity profile differ in terms of their light properties. In this way, the formation of disturbing interferences can be prevented, such that disturbing speckle patterns are substantially eliminated, whereby the quality of the beam shape can be significantly improved, in particular for laser processing processes.