Experimental and numerical study of the CO2 laser-polishing edge effect on silica surface

• Published in: International journal of advanced manufacturing technology 2023-09, Vol.128 (3-4), p.1483-1491
• Main Author: Dogan, Yusuf
• Format: Article
• Language: English
• Subjects: CAE) and Design; Carbon dioxide; Carbon dioxide lasers; Computer-Aided Engineering (CAD; Deformation effects; Edge effect; Engineering; Finite element method; Heat flux; Heat transfer; Industrial and Production Engineering; Laminar flow; Laser beams; Laser machining; Lasers; Mechanical Engineering; Media Management; Optical components; Original Article; Polishes; Polishing; Silicon dioxide; Substrates; Surface properties; Surface roughness
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-023-12015-7

CO 2 laser glass polishing is an effective and widely studied method to acquire smooth and high-quality surfaces. In this study, the CO 2 laser beam approximately 5 times larger than the width of the sample is used with slow scanning to polish a millimeter-sized silica rod sample. We have successfully reduced the Gaussian-filtered RMS surface roughness to 6.4 nm for an area of over 1.3 mm 2 . However, deformations are observed on the edges of the sample after the polishing process. This work focuses on the reasons and the approaches to overcome this deformation on the edges, presented for the first time in the literature. Experiments have revealed that these deformations result from the difference between the temperatures of the sample and its surrounding, not from the beam shape. A couple of approaches including masking, laser exposure timing, increasing the substrate temperature, and changing the substrate material, have been proposed to eliminate the deformations. Among these, replacing tungsten with silica as the substrate has been effective, and the direction of deformation is changed from upward to downward yielding smooth edges. The finite element method is used to further interpret the reason for this change with multiphysics like heat flux, heat transfer in solid and liquid, laminar flow, and deformed geometries. This work is believed to provide insight for future laser machining studies concerning the surface quality of millimeter and micron-scale optical components.