Characterization of femtosecond laser-structured materials using interferometric microscopy: local spectroscopy, colorimetry, and topography

Optical metrology plays a crucial role in the characterization of microfabricated structures, providing insights into their spectral, colorimetric, and topographical properties. In this work, we employ different interference microscopes to investigate a surface structured sample prepared using femtosecond laser processing. The structuring was performed with a Tangerine laser source (Amplitude System), operating at a wavelength of 1030nm and a pulse duration of 290fs. The laser features a maximum average power of 30W and a maximum repetition rate of 2MHz, while the measured spot size is 60μm in diameter. Local spectroscopy is performed to analyze the optical response at specific regions of the micro structured surface, enabling the identification of spectral variations at the microscale. Colorimetric measurements provide additional information on the perceived color changes induced by the laser processing, which can be linked to surface morphology and material modifications. Furthermore, interferometry is utilized to obtain high-resolution 3D surface profiles of the topography, revealing the depth and uniformity of the laser-induced structures. The combination of these techniques enables comprehensive optical characterization of the sample, offering valuable data for optimizing laser processing parameters and understanding of the underlying physical effects. This multimodal approach is particularly relevant for applications requiring precise control over surface properties, such as in photonic device fabrication and functional material engineering.