Reflective Line-Beam Homogenization for UV Laser Machining
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Solution Overview
Problem
Conventional laser processing systems using refractive components suffer from high optical losses, material degradation, and reduced service life, especially when using UV radiation, which limits their efficiency and longevity in generating uniform line beams for applications like laser annealing and lift-off processes.
Innovation Solution
A laser processing system employing catadioptric optical systems with reflective components, such as mirrors, instead of lenses, to reduce optical losses and enhance energy density, allowing for a more compact and efficient generation of line beams with high aspect ratios and uniform intensity distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refractive components (lenses) are used in the condenser system, then the system can focus and shape the laser beam, but optical losses increase and service life decreases due to material degradation from UV radiation
Solution Approach 1:
The patent replaces refractive optical components (lenses) with reflective optical components (mirrors) in the condenser system. This substitution eliminates material absorption and degradation issues associated with UV radiation, thereby reducing optical losses and extending the service life of the optical system while maintaining the ability to focus and shape the laser beam.
2Volume of moving object
If conventional refractive optical systems are used, then beam shaping is achieved, but the system size increases and compactness is reduced
Solution Approach 1:
The patent employs curved mirror surfaces with specific radii of curvature to achieve beam focusing and shaping. The first mirror has a first radius of curvature and the second mirror has a second radius of curvature, allowing compact arrangement of optical components while maintaining precise beam shaping capability through the reflective geometry.
3Device complexity
If reflective optics with different radii of curvature are used, then compact system design is achieved, but optical alignment precision must be maintained
Solution Approach 1:
The patent uses a composite optical system combining two mirrors with different radii of curvature (first radius and second radius) in a catadioptric arrangement. This composite reflective system achieves compact beam shaping while the specific geometric configuration provides inherent alignment stability, reducing the sensitivity to alignment errors compared to single-element systems.
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 use of reflective optics in the laser processing system significantly reduces optical losses, increases the service life of the optics, and achieves higher energy density on the workpiece, enabling more efficient and precise processing with longer beam profiles while maintaining high homogeneity.
Implementation Method 1
A laser processing system employing catadioptric optical systems with reflective components, such as mirrors, instead of lenses
Implementation Method 2
Irradiation heats and melts a layer of amorphous silicon, which is then converted into a polycrystalline Si layer upon re-solidification
Implementation Method 3
Irradiation heats and melts a layer of amorphous silicon
Data Source
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AI summary
A laser machining system (100) for creating a laser beam with a linear beam cross section with a short axis and, perpendicular thereto, a long axis in a machining plane (105) comprises a laser beam source (102) for creating a raw laser beam, a beam widening system (120), connected downstream of the laser beam source, for receiving the raw laser beam and for creating a widened laser beam, and a homogenisation system, connected downstream of the beam widening system, for receiving the widened laser beam and for creating a laser beam that is homogenised with respect to the light intensity distribution and has a linear beam cross section in the machining plane. The homogenisation system has a first homogenisation arrangement for homogenisation along the short axis and a second homogenisation arrangement for homogenisation along the long axis, wherein each of the homogenisation arrangements has optical elements (140-1, 140-2) for splitting the laser beam into a plurality of partial beams and a condenser system (150-1, 150-2) for superposing the partial beams in a superposing plane. The first homogenisation arrangement has a first condenser system (150-1) with at least one first mirror (150-1A, 150-1B) and the second homogenisation arrangement has a second condenser system (150-2) with at least one second mirror (150-2A, 150-2B).