Laser light is often used for illumination techniques due to its high intensity and beam directionality. When light with high spatial and temporal coherence reflects off an object whose roughness is on the order of the wavelength, mutual interference of scattered light occurs. This leads to a random distribution of light intensity on the interaction surface, known as a speckle pattern. Typically, systems for laser remote welding use laser light for scanning the surface and detecting the weld seam. For this purpose, an industrial camera is used, which is adversely affected by laser speckle in much the same way as noise affects measurements. It impacts the accuracy of determining the center of the detected weld seam, which can result in improper joining of both welding partners. As part of the master's thesis, we studied the use of low-coherent lights for illuminating the area of laser welding. This approach aimed to improve the accuracy of weld seam detection, a crucial component in the welding process. Our work was based on the hypotesis that using such light could help reduce the unwanted phenomenon of laser speckle, which decreases the quality and efficiency of the processing procedure. We tested the hypothesis by comparing the tracking accuracy of the same weld seam using laser and LED illumination of different wavelengths. The research results indicate that using LED illumination can be effective in reducing laser speckle and offers the ability to accurately track the weld seam in laser welding.
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