Coupling of focused laser pulse to surfaces of transparent materials studied by time-resolved imaging technique

• Published in: Applied physics. A, Materials science & processing Vol. 79; no. 4-6; pp. 1031 - 1033
• Main Authors: TADANO, J, KUMAKURA, H, ITO, Y
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Berlin Springer 01.09.2004
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron and ion emission by liquids and solids; impact phenomena; Exact sciences and technology; Focusing; Harmonic radiation; Impact phenomena (including electron spectra and sputtering); Joining; Laser-beam impact phenomena; Lasers; Light (visible radiation); Nanostructure; Physical properties; Physics; Polymer industry, paints, wood; Polymethyl methacrylates; Properties and testing; Radiation influence; Roughness; Technology of polymers; Radiation effects; Shock waves; Laser pulse; PMMA; Laser radiation; Images; Photoelasticity; Transparent material; Time resolved spectra; Shadowscopy
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-004-2621-2

Short and intense laser pulse can process the surface and the inside of transparent materials by focusing the pulse at the desired position. Here we report the interaction of fundamental radiation (1064 nm) of the Q-switched Nd:YAG laser to the surface of PMMA as observed by an imaging system with nanosecond time resolution. The system used fundamental radiation of a Q-switched Nd:YAG laser as a processing laser and second harmonic radiation (532 nm) of another Nd:YAG laser as illuminating light. We observed shock waves which propagate into the material and into the atmosphere by shadowgraph and photoelastic method. Surface roughness of a sample is expected to affect the coupling of light and transparent materials for both normal and focused laser light. Our results have revealed the effects visually. For roughness larger than 0.6 {/content/FQGTV144LN4G8PU2/xxlarge956.gif}m, all energy is absorbed at the surface, while the larger part of the energy is absorbed inside the material as the surface becomes smoother.