Diffractive Phase Mask for Elongated Laser Focus Shaping
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Solution Overview
Problem
Existing optical systems for laser material processing struggle to efficiently shape laser beams for processing transparent materials, as they often result in damage to optical elements and require complex configurations to achieve the necessary high intensities for nonlinear absorption, which limits the precision and efficiency of beam shaping.
Innovation Solution
A diffractive optical beam shaping element with an areally configured phase mask that imposes a plurality of beam shaping phase distributions on the laser beam, creating a virtual optical image that is imaged into an elongated focus zone, allowing for tailored volume absorption and processing of transparent materials with high aspect ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical systems are used to shape laser beams for transparent materials, then the system configuration becomes complex, but the beam shaping precision and efficiency deteriorate due to optical element damage and limited intensity control
Solution Approach 1:
The phase mask is divided into multiple local phase regions, each responsible for shaping a specific portion of the beam. This segmentation allows independent optimization of different beam areas while simplifying the overall optical system configuration.
Solution Approach 2:
Different regions of the phase mask are assigned different local phase distributions tailored to specific processing requirements. Each local region imparts customized phase modifications to achieve precise beam shaping for different areas of the transparent material.
2Illumination intensity
If high intensities are achieved through complex optical configurations, then nonlinear absorption is enabled, but optical elements suffer from damage due to the high intensity requirements
Solution Approach 1:
The phase mask pre-shapes the beam profile before it reaches the transparent material, creating the necessary intensity distribution in advance. This preliminary beam shaping enables achieving required intensities without relying on complex post-focusing optical elements that would be exposed to damaging high intensities.
Solution Approach 2:
The phase mask acts as an intermediary element that transforms the beam profile to achieve the desired intensity distribution. By performing beam shaping at this intermediate stage, the system avoids exposing other optical elements to damaging high intensities while still achieving the necessary conditions for nonlinear absorption.
3Productivity
If volume absorption is used for transparent materials, then processing capability is improved, but the focus zone geometry becomes limited, reducing aspect ratio control
Solution Approach 1:
Different local phase regions are designed with specific phase distributions to create focus zones with tailored geometries. This allows independent control of focus zone shape and aspect ratio in different areas, enabling precise geometric control while maintaining volume absorption processing capability.
Solution Approach 2:
The phase mask parameters are optimized to transform the beam profile into configurations that produce focus zones with high aspect ratios. By adjusting phase distribution parameters across different mask regions, the system achieves both improved processing capability and controlled focus zone geometry.
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 and precise processing of transparent materials by generating elongated focus zones with high aspect ratios, reducing the need for complex optical configurations and minimizing damage to optical elements, while allowing for selective etching and structuring with improved separation quality and reduced surface particles.
Implementation Method 1
diffractive optical beam shaping element... areally configured phase mask that is configured for imposing a plurality of beam shaping phase distributions on the laser beam
Implementation Method 2
electrons can absorb that much energy by inverse bremsstrahlung that further electrons are set free by impacts, so that the rate of generating electrons overcomes that rate of recombination
Implementation Method 3
electrons can absorb that much energy by inverse bremsstrahlung
Data Source
AI summary
A diffractive optical beam shaping element for imposing a phase distribution on a laser beam that is intended for laser processing of a material includes a phase mask that is shaped as an area and is configured for imposing a plurality of beam shaping phase distributions on the laser beam incident on to the phase mask. A virtual optical image is attributed to at least one of the plurality of beam shaping phase distributions, wherein the virtual image can be imaged into an elongated focus zone for creating a modification in the material to be processed. Multiple such elongated focus zones can spatially add up and interfere with each other, to modify an intensity distribution in the material and, for example, generate an asymmetric modification zone.