Temporal Pulse Overlap in Laser Machining for Faster Precision Ablation
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Solution Overview
Problem
Existing laser machining methods lack the ability to improve accuracy and speed without increasing system complexity, particularly in the use of picosecond and femtosecond pulse durations for materials processing.
Innovation Solution
A pulse laser system that generates both short and long duration pulses, with the short pulses being temporally overlapped with a relative delay less than the long duration, utilizing an injection system, optical amplifier, beam combiner, and optional compressors and nonlinear optical systems to achieve precise laser-matter interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If only short duration pulses (100 fs to few hundred ps) are used for laser machining, then manufacturing precision is improved, but productivity is limited due to slower processing speed
Solution Approach 1:
The long duration pulse (nanosecond scale) is applied before the short duration pulse to preheat the material and modify its properties. This preliminary thermal action reduces the ablation threshold and prepares the material for more efficient removal by the subsequent short pulse, thereby increasing processing speed without sacrificing the precision achieved by the short pulse
Solution Approach 2:
The system creates a continuous processing action by overlapping the long and short pulses in time and space. The long pulse provides continuous heating while the short pulse delivers precise ablation, creating a synergistic effect that maintains both high precision and high productivity throughout the machining process
2Productivity
If pulse repetition frequency is increased to improve productivity, then processing speed is improved, but system complexity increases due to architectural constraints
Solution Approach 1:
The system uses periodic pulse trains (bursts) where groups of short pulses are delivered at high repetition frequency within a nanosecond envelope. This periodic structure allows the system to achieve high average productivity while maintaining manageable peak power requirements and avoiding the need for complex continuous high-frequency operation
Solution Approach 2:
The long duration nanosecond pulse serves as a preliminary action that prepares the material before the high-frequency short pulses are applied. This preliminary heating reduces the energy required for each subsequent ablation pulse, allowing higher repetition frequencies to be used without proportionally increasing the total system complexity
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
Enhances material processing efficiency by heating the material with long pulses before ablation by short pulses, allowing for improved accuracy and speed in drilling, cutting, and surfacing of transparent materials.
Implementation Method 1
an optical amplifier system adapted to receive the source pulse and to generate an amplified pulse
Implementation Method 2
a beam combiner adapted to combine the source pulse and the other source pulse which are temporally overlapped
Implementation Method 3
a nonlinear optical system adapted to convert the wavelength of the amplified pulse
Implementation Method 4
a compressor adapted to receive the amplified pulse and to generate a compressed amplified pulse of short duration
Implementation Method 5
The long duration pulse starts before the short duration pulse. Thus, the long duration pulse heats the material to prepare it before the application of the short duration pulse
Implementation Method 6
The short duration pulse ablates the material with an increased efficiency relative to a short pulse applied alone
Implementation Method 7
The short duration pulse ablates the material
Data Source
AI summary
Disclosed is a pulse laser system including an injection system, an optical amplifier system and a beam combiner, the pulse laser system being designed to generate, on the one hand, an amplified pulse of short duration between 100 fs and a few hundred picoseconds and, on the other hand, another amplified pulse of long duration between a few picoseconds and several hundred nanoseconds, the amplified pulse of short duration and the other amplified pulse of long duration being from the same optical amplifier system and the amplified pulse of short duration being temporally overlapped with a relative delay with the other amplified pulse of long duration, the relative delay being less than or equal to the long duration.