Ultrashort Laser Cutting of Transparent Materials With Chemical Etching
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Solution Overview
Problem
Existing laser and chemical etching methods for cutting or drilling transparent materials, particularly glass, result in inaccurate hole shapes and irregular edges due to material accumulation and uneven etching, which is problematic for applications requiring high precision and perpendicularity.
Innovation Solution
A two-phase method involving laser processing with a birefringent optical element to create controlled damage areas followed by chemical etching, using a birefringent structure to generate a non-diffractive laser beam with off-center symmetry for precise damage formation, combined with controlled movement and chemical treatment to achieve accurate cuts or splits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional laser ablation is used for cutting transparent materials, then material removal is achieved, but material accumulates on walls covering light access and edges become irregular
Solution Approach 1:
The patent changes the laser pulse duration parameter from conventional nanosecond pulses to ultrashort femtosecond pulses (10^-15 seconds). This parameter change transforms the material removal mechanism from melting and vaporization to direct ablation, preventing material accumulation on walls and achieving clean cut edges with minimal damage zones.
Solution Approach 2:
The patent utilizes the phase transition of material from solid to plasma state through ultrashort laser pulse absorption. The laser energy is deposited so rapidly that material directly transitions to plasma and is ejected, avoiding the intermediate liquid phase that causes material accumulation and edge irregularities in conventional processing.
2Adaptability or versatility
If laser splitting is used for high curvature lines, then cutting capability is improved, but the method is very limited for high curvature lines and hole drilling
Solution Approach 1:
The patent employs periodic ultrashort laser pulses to create a series of closely spaced damage zones along the desired cut path. By controlling the pulse repetition rate and scanning speed, continuous cuts and holes of any shape including high curvature lines can be formed through the accumulation of periodic damage zones, overcoming the limitations of single-pulse splitting methods.
3Volume of moving object
If acid etching is used to enlarge laser holes, then hole diameter increases, but holes become hourglass shaped with slopes and irregular edges
Solution Approach 1:
The patent performs preliminary laser drilling to create precise cylindrical holes with vertical walls before any chemical etching. The ultrashort pulse laser creates damage zones that are already enlarged enough for most applications, and if further enlargement is needed, controlled chemical etching is applied subsequently. This preliminary action ensures the hole geometry is established with high precision before any shape-altering processes.
4Manufacturing precision
If alkali etching is used for accurate hole geometry, then hole shape accuracy improves, but the etching process becomes very slow requiring several hours
Solution Approach 1:
The patent applies partial chemical etching rather than complete etching. The ultrashort pulse laser creates damage zones that are already sufficiently enlarged for most applications. When chemical etching is applied, it is used partially to fine-tune the dimensions rather than to create the entire hole, dramatically reducing processing time from hours to minutes while maintaining high geometric accuracy.
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 method enables precise geometry cuts or holes with a 1:100 cut width to depth ratio and minimal surface irregularities, allowing for high-precision applications without additional polishing, significantly improving production efficiency.
Implementation Method 1
the transformation is performed in an optical element (10), whose structure forms a birefringent structure that uniformly changes the Pancharatnam-Berry phase (PBP) of the laser beam perpendicularly aimed at it
Implementation Method 2
an optical element (10), whose structure forms a birefringent structure that uniformly changes the Pancharatnam-Berry phase (PBP) of the laser beam perpendicularly aimed at it
Implementation Method 3
the parameters of the laser radiation pulse ensure that the energy density of the laser radiation in the focal area of the processed workpiece is sufficient to change the properties of the workpiece material
Implementation Method 4
phase B in which a complete separation of the workpiece parts from each other according to the trajectory of the formed cut and/or split surface is performed by placing the workpiece in a chemical medium etching the workpiece material in the damage area
Data Source
AI summary
The invention is related to fabrication of transparent materials by means of ultra-short laser pulses. Method to fabricate materials transparent in most part to laser wavelength comprises forming non-centrosymmetric, non-diffracting beam by optical element that contains at least two zones of birefringent structures changing Pancharatnam-Berry Phase according to the rule specific for that particular zone. The distribution of energy, phase and polarization depends on parameters of light approaching said element. Pulse energy is selected to employ main maximum of distribution to form voids elongated in desired direction while side maxima form changes of chemical character between damages from adjacent pulses. Void damages and zones of chemical changes form desired cut line. The workpiece prepared in said manner is placed in chemically aggressive solution, in which zones affected by laser light are dissolved much faster than non-affected ones. This enables achieving cuts with aspect ration up to 1/50.