Classification of Photo-Acoustic Emission in Direct Laser Interference Pattering for Identifying the Spatial Period

Direct Laser Interference Patterning (DLIP) is a versatile tool used to produce microstructures for functionalized surfaces on different materials. However, monitoring strategies are needed to ensure repeatability and quality control during the fabrication of surface patterns with micro- and submicron resolution features. This study proposes a new approach for identifying the spatial period on the surface using airborne acoustic emission during DLIP. The acoustic emission parameters from a single laser pulse on the material are analyzed using different prediction algorithms to classify and compare different spatial periods. Line-like patterns were produced on aluminum substrates using a pulsed laser source, and the laser fluence was varied to obtain variation in the data set. The preliminary results show that the four algorithms can detect and identify the spatial period for different laser fluences with an accuracy of up to 96%. This approach could be used for an automated setup workflow and eliminates the need for manual measurement of this parameter. It is an important step towards a fully automated initialization of surface processing in the micrometer range.