Method for determining the operational conditions of a method for high-repetition rate femtosecond laser ablation for a given material and method for laser welding between parts of a determined material

Abstract

The invention proposes a method for determining the operational conditions of a method for high-repetition rate femtosecond laser ablation for a given material comprising a first step of determining a set of parameters of a burst of laser pulses adapted to generate an ablation crater in the material, the set of parameters comprising an intra-burst repetition frequency f between several hundred MHz and 100 GHz, a number N of pulses of the burst of laser pulses equal to a number Ne of heating and ablation pulses, with Ne being defined by the equation Nc = (L2.f) / D, where L represents a test depth and D represents a thermal diffusion coefficient of the material to be ablated, with Nc being greater than or equal to 10, a characteristic total fluence FTchar of the burst of pulses and a characteristic fluence per pulse Fchar=FTchar / Nc per pulse below an ablation threshold fluence Fs1 of the material by a single laser pulse.

Description

technical field [0001] The present invention relates generally to the field of laser ablation and welding methods. [0002] More particularly, it relates to the field of methods for laser ablation of surfaces of materials by means of bursts of laser pulses or continuous bursts of laser pulses at high repetition rates in the order of GHz. Background technique [0003] Surface ablation of materials by microsecond, nanosecond, picosecond or femtosecond laser pulses is a technique widely used today to modify the surface of materials in a controlled manner (drilling, cutting, structuring). The materials involved are diverse and include, for example, semiconductors, metals, dielectric materials or biological tissues. [0004] Femtosecond pulses generally result in the best processes, but these pulses are also less ablation efficient than longer pulses on the nanosecond scale. The latest possibility of lasers with higher average powers allows the use of higher repetition rates in...

AI Technical Summary

Problems solved by technology

Such a large number of operating parameters makes it difficult to determine the most suitable operating parameters for a given material

Furthermore, the exact nature of the mechanism for laser ablation of materials at GHz repetition rates via bursts of femtosecond pulses remains controversial in the scientific literature.

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