image: Figure |Working principles of ultrafast dual-modal microscopy and spatiotemporal imaging results. (a) Optical system principle of the dual-modal ultrafast imaging technique. The red indicates the pump light (at 800 nm), while the violet represents the probe light (at 400 nm). A delay line controls the optical path difference between the two beams.(b) Imaging procedure overview. Inverse Fourier transforms are applied to the 0th and +1st orders of the original image's Fourier spectrum to obtain dual-modal imaging results for reflectivity and topography.(c) Dual-modal spatiotemporal imaging of the dynamics of LIPSS formation on a silicon surface irradiated by different shots of cross-polarized pulse pair.
Credit: Qianyi Wei, Jielei Ni et al.
Ultrafast laser-material interactions are pivotal for advanced manufacturing, yet existing techniques often fail to capture comprehensive structural and optical changes simultaneously. In a new paper published in Light: Advanced manufacturing, a team of researchers, led by Professor Changjun Min from Shenzhen University, have developed a dual-modal spatiotemporal microscopy system that integrates pump-probe and interferometric imaging. This innovation achieves resolutions of 236 nm spatially and 256 fs temporally, enabling femtosecond-time-scales observation of laser-induced periodic surface structure (LIPSS) formation, strengthening, and erasure on silicon.
The system simultaneously records 2D reflectivity and 3D topography, revealing that LIPSS patterns arise from modulated ablation during energy deposition rather than molten material flow. This insight challenges conventional hydrodynamic models, offering a refined understanding of ultrafast laser-material dynamics.
“By combining two complementary imaging modalities, we decode both transient optical and structural changes, providing a holistic view of ablation processes,” explained the team. The method’s high resolution and accuracy enhance precision in laser manufacturing and surface modification, with potential applications in aerospace, biomedical engineering, and microelectronics.
Future work aims to further boost resolutions using immersion objectives and shorter probe wavelengths. This breakthrough bridges critical gaps in ultrafast process analysis, paving the way for optimized laser fabrication and real-time quality control in industrial settings.
Journal
Light: Advanced Manufacturing
Article Title
Dual-modal spatiotemporal imaging of ultrafast dynamics in laser-induced periodic surface structures