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technical paper
Tackling Micro-Processing Challenges with Beam Shaping
keywords:
micro-processing
femtosecond
multi-plane light conversion
beam shaping
A fundamental understanding of ablation in different incidence angles is indispensable to expand the result to volume ablation where non-perpendicular irradiation exists. So far, no study with this orientation has been conducted in the category of volume laser machining. In this study, a nanosecond laser with different fluencies was utilized for single-point ablation experiments. The effect of incidence angles of 0°, 30° and, 60° on the ablation depth and the crater geometry was evaluated. Different laser pulse numbers are also considered. The results show that the ablation depth for the 0° and 30° angles is almost in the same range for the initial pulses, but afterward, the ablation depth for the incidence 30° drops considerably. As the number of incident pulses increases, the ablation depth first develops approximately linearly and then grows exponentially. By changing the incident from 0° to 60°, the affecting area changes as well. The affecting area could be categorized into two distinct areas: (1) ablation area (A.A) where the crater ablation depth rapidly increases for the first 20 pulses and then, as more incident pulses arrive, it does not grow anymore and reaches a plateau due to the increase in the ablation depth. The second area (2) is the heat-affected area (H.A.A) of the crater where no further ablation occurs, but due to heat accumulation, it becomes constantly bigger when more incident pulses strike the crater.