3D optical profilometry using a four-core optical fiber and the 2D continuous wavelet transform method

OpenAlex Türkçe

This study presents an optical profilometry approach implemented using a four-core, multimode optical fiber in combination with the two-dimensional Continuous Wavelet Transform (2D-CWT). A He–Ne laser beam with a wavelength of 632.8 nm and a spot size of 0.7 mm was precisely aligned and coupled into the central region of a four-core optical fiber approximately 50 cm in length. To mitigate environmental noise and mechanical vibrations, the fiber was wounded around an iron rod. Through this configuration, horizontal and vertical interference fringe patterns were generated and projected onto two distinct test specimens: a half-egg-shaped object with a height of 4.1 mm and length of 19.3 mm, and a star-shaped object with a height of 2.1 mm and length of 19.2 mm. The fringe distortions (phase shifts) induced by the surface height variations of the specimens were captured using a CMOS camera and subsequently processed in MATLAB. By employing a 2D-CWT-based fringe separation algorithm, individual wrapped phase maps were extracted and unwrapped to reconstruct the three-dimensional surface profiles. Furthermore, a cross-sectional comparison of the reconstructed 3D profile of the half-egg specimen with its corresponding geometric data obtained from CAD was performed to validate the results.