Multi-focus optics for laser processing transparent materials
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Solution Overview
Problem
Conventional laser material processing techniques face challenges in achieving efficient and controlled processing of brittle materials due to spherical aberration when focusing laser beams inside transparent materials, leading to reduced energy concentration and increased processing time, especially with high numerical aperture optics and ultra-short pulse lasers.
Innovation Solution
The use of optical systems with birefringent lenses forming multiple focuses along the optical axis, combined with movable lenses to compensate aberrations, allows for variable depth processing and optimized energy distribution, enabling efficient material disruption or modification without the limitations of traditional systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional focusing optics are used to focus laser beams inside transparent materials, then material processing can be achieved, but spherical aberration occurs leading to reduced energy concentration and increased processing time
Solution Approach 1:
The patent divides the single focused spot into multiple focused spots arranged in a matrix pattern. By segmenting the laser energy distribution across multiple focal points, the system maintains high energy concentration at each point while collectively processing a larger volume of material, thereby improving processing speed without sacrificing energy concentration
Solution Approach 2:
The patent transitions from conventional single-point focusing to multi-point focusing by arranging focal spots in a matrix pattern across the transverse plane. This dimensional expansion allows simultaneous processing of multiple locations, increasing productivity while maintaining the optical system's numerical aperture and energy concentration capabilities
2Manufacturing precision
If multi-step processing with changing focusing depth is used to improve quality and controllability, then processing quality improves, but processing time increases and alignment tolerances become tighter
Solution Approach 1:
The patent combines multiple focusing depths into a single processing step by creating a matrix of focal spots that spans different depths within the material. This merging of multi-depth processing into one simultaneous operation maintains processing quality across different depths while eliminating the time penalty associated with sequential multi-step processing
Solution Approach 2:
The patent enables continuous processing across different depths by maintaining a continuous matrix of focal spots throughout the material volume. This continuous action eliminates the interruptions and repositioning required in multi-step methods, thereby improving productivity while maintaining consistent processing quality across the entire depth range
3Productivity
If diffractive optical elements are used to create multiple focuses, then multiple processed areas can be created, but manufacturing costs increase and resistance to powerful laser radiation decreases
Solution Approach 1:
The patent creates multiple focal spots by using a diffractive optical element that copies the single input beam into multiple beam copies arranged in a matrix pattern. Each copied beam is focused to a separate spot, enabling multi-focus capability while using a single robust optical component that can withstand high laser power
Solution Approach 2:
The diffractive optical element acts as an intermediary that transforms a single high-power laser beam into multiple lower-power focused spots. This intermediary function allows the system to achieve multi-focus capability while distributing the laser power load, thereby maintaining the resistance of individual optical components to powerful laser radiation
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 results in improved processing speed, reduced roughness of cutting edges, and increased resistance to ultra-short pulse lasers, with precise control over the processed region, enhancing the efficiency and quality of laser material processing.
Implementation Method 1
optical systems with birefringent lenses forming multiple focuses along the optical axis
Implementation Method 2
movable lenses to compensate aberrations
Implementation Method 3
focusing laser radiation on a surface of the material workpiece or inside bulk material
Implementation Method 4
material disruption can occur due to multiphoton absorption
Data Source
AI summary
Methods, systems, devices and apparatus for laser processing of transparent or partially transparent materials by focusing laser radiation on a surface of a material workpiece or inside the material workpiece and creating elongated processed regions with variable and controlled depth using focusing optical system with air-spaced optical components, forming three or more multiple focuses along the optical axis and compensating aberrations induced while light focusing inside the material workpiece. The focusing optical system can have an aplanatic design, with lenses made from birefringent materials combined with lenses from isotropic materials, or objectives, or zoom optical system, or waveplates. Material processing effects such as material disruption or modification of material properties are produced due to the interaction of focused laser radiation with material in elongated volume processed regions and are multiple repeated along the processing path by relative motion between the material workpiece and the focusing optical system being realized with a scanning device.