CHARACTERIZATION OF MICROSTRUCTURED SURFACE TEXTURE USING ANGLE-RESOLVED SCATTERING

Date

2025-4-17

Author

Başaran, Nuray

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Accurate characterization of microstructured surfaces is essential for evaluating their optical performance, particularly in applications involving light scattering, sensing, and anti-reflective engineering. This study presents a systematic investigation of angularly resolved scattering (ARS) from laser-textured silicon surfaces to extract structural information at the microscale. A custom-built ARS measurement setup was employed to record the intensity distribution of reflected light as a function of scattering angle, with the illumination fixed at 45° incidence. The samples comprised both periodic (grating-like) and aperiodic (rough) surface morphologies, fabricated by varying femtosecond laser processing parameters. To validate and interpret the scattering profiles, two complementary approaches were utilized: frequency-domain analysis of surface topography via 2D Fast Fourier Transform (FFT) on SEM and AFM images, and angular-domain analysis of optical scattering patterns. Periodic samples exhibited distinct diffraction orders, and the extracted peak positions were used to estimate spatial periods via the grating equation, which closely matched FFT results. In contrast, rougher surfaces fabricated at higher laser powers displayed broadened angular profiles, increased diffuse background levels, and the absence of well-defined diffraction orders. Extended scans over 10°–120°, centered around the specular reflection angle, revealed how increasing surface irregularity leads to loss of angular coherence and redistribution of scattered intensity. The combined optical and morphological analyses confirm that ARS provides a sensitive, non-destructive tool for quantifying both periodicity and surface roughness. The findings also highlight the strong correlation between laser processing conditions and the evolution of surface texture, bridging the gap between fabrication parameters and optical functionality.

Subject Keywords

Angle-Resolved Scattering, Diffraction Theory, Surface Periodicity Analysis, Microstructured Surfaces, Optical Characterization

URI

https://hdl.handle.net/11511/114923

Collections

Graduate School of Natural and Applied Sciences, Thesis