Numerical Analysis and Process Study of Picosecond Laser Marking on Apple Surface

Abstract

Laser direct marking of durable and sturdy information labels on the surface of fruits and vegetables is of great research significance. However, the use of CO2 lasers to mark thin-skinned fruits and vegetables often results in significant damage, which affects their preservation and sales. In this study, ultra-short pulse lasers were used for laser direct marking on thin-skinned fruits and vegetables to reduce surface damage during processing and improve the applicability of laser direct marking on fruits and vegetables. To explore the mechanism of interaction between ultra-short pulse lasers and the skin of fruits and vegetables and optimize the process, the optical parameters of fruits and vegetables were introduced in this study. A laser ablation model of ultra-short pulse lasers on apples was established, and the effects of laser pulse energy, scanning speed, and laser frequency on the marking results were analyzed. Based on a picosecond laser galvanometer processing system, corresponding process experiments were designed to verify the results of the ablation model. The results showed that, for single-pulse ablation, the depth of ablation increased linearly with the increase of pulse energy, while the increase in ablation width was not obvious. For moving multi-pulse ablation, the depth of ablation increased proportionally with the increase of pulse energy. With the increase of scanning speed, the depth of moving multi-pulse ablation decreased exponentially, while with the increase of laser frequency, the depth of moving multi-pulse ablation increased proportionally. The established ultra-short pulse laser ablation model for thin-skinned fruits and vegetables in this study is of great significance for predicting processing effects and improving processing efficiency, and the designed process experiments provide reference for the high-quality and efficient production of information labels on the surface of thin-skinned fruits and vegetables.

Keywords: Picosecond laser marking, Numerical simulation model, Single-pulse ablation, Multi-pulse ablation